Merge branch 'mc-1.16.x' into mc-1.18.x

build.gradle.kts

@@ -204,7 +204,7 @@ tasks.processResources {
     inputs.property("forgeVersion", libs.versions.forge.get())
     inputs.property("gitHash", cct.gitHash)
 
-    filesMatching("data/computercraft/lua/rom/help/credits.txt") {
+    filesMatching("data/computercraft/lua/rom/help/credits.md") {
         expand(mapOf("gitContributors" to cct.gitContributors.get().joinToString("\n")))
     }
 

doc/stub/fs.lua

@@ -1,64 +0,0 @@
---- @module fs
-
---- Returns true if a path is mounted to the parent filesystem.
---
--- The root filesystem "/" is considered a mount, along with disk folders and
--- the rom folder. Other programs (such as network shares) can exstend this to
--- make other mount types by correctly assigning their return value for getDrive.
---
--- @tparam string path The path to check.
--- @treturn boolean If the path is mounted, rather than a normal file/folder.
--- @throws If the path does not exist.
--- @see getDrive
--- @since 1.87.0
-function isDriveRoot(path) end
-
---[[- Provides completion for a file or directory name, suitable for use with
-@{_G.read}.
-
-When a directory is a possible candidate for completion, two entries are
-included - one with a trailing slash (indicating that entries within this
-directory exist) and one without it (meaning this entry is an immediate
-completion candidate). `include_dirs` can be set to @{false} to only include
-those with a trailing slash.
-
-@tparam[1] string path The path to complete.
-@tparam[1] string location The location where paths are resolved from.
-@tparam[1,opt=true] boolean include_files When @{false}, only directories will
-be included in the returned list.
-@tparam[1,opt=true] boolean include_dirs When @{false}, "raw" directories will
-not be included in the returned list.
-
-@tparam[2] string path The path to complete.
-@tparam[2] string location The location where paths are resolved from.
-@tparam[2] {
-    include_dirs? = boolean, include_files? = boolean,
-    include_hidden? = boolean
-} options
-This table form is an expanded version of the previous syntax. The
-`include_files` and `include_dirs` arguments from above are passed in as fields.
-
-This table also accepts the following options:
- - `include_hidden`: Whether to include hidden files (those starting with `.`)
-   by default. They will still be shown when typing a `.`.
-
-@treturn { string... } A list of possible completion candidates.
-@since 1.74
-@changed 1.101.0
-@usage Complete files in the root directory.
-
-    read(nil, nil, function(str)
-        return fs.complete(str, "", true, false)
-    end)
-
-@usage Complete files in the root directory, hiding hidden files by default.
-
-    read(nil, nil, function(str)
-        return fs.complete(str, "", {
-            include_files = true,
-            include_dirs = false,
-            included_hidden = false,
-        })
-    end)
-]]
-function complete(path, location, include_files, include_dirs) end

doc/stub/http.lua

@@ -1,177 +0,0 @@
---- Make HTTP requests, sending and receiving data to a remote web server.
---
--- @module http
--- @since 1.1
--- @see local_ips To allow accessing servers running on your local network.
-
---- Asynchronously make a HTTP request to the given url.
---
--- This returns immediately, a @{http_success} or @{http_failure} will be queued
--- once the request has completed.
---
--- @tparam      string url   The url to request
--- @tparam[opt] string body  An optional string containing the body of the
--- request. If specified, a `POST` request will be made instead.
--- @tparam[opt] { [string] = string } headers Additional headers to send as part
--- of this request.
--- @tparam[opt] boolean binary Whether to make a binary HTTP request. If true,
--- the body will not be UTF-8 encoded, and the received response will not be
--- decoded.
---
--- @tparam[2] {
---   url = string, body? = string, headers? = { [string] = string },
---   binary? = boolean, method? = string, redirect? = boolean,
--- } request Options for the request.
---
--- This table form is an expanded version of the previous syntax. All arguments
--- from above are passed in as fields instead (for instance,
--- `http.request("https://example.com")` becomes `http.request { url =
--- "https://example.com" }`).
---
--- This table also accepts several additional options:
---
---  - `method`: Which HTTP method to use, for instance `"PATCH"` or `"DELETE"`.
---  - `redirect`: Whether to follow HTTP redirects. Defaults to true.
---
--- @see http.get  For a synchronous way to make GET requests.
--- @see http.post For a synchronous way to make POST requests.
---
--- @changed 1.63 Added argument for headers.
--- @changed 1.80pr1 Added argument for binary handles.
--- @changed 1.80pr1.6 Added support for table argument.
--- @changed 1.86.0 Added PATCH and TRACE methods.
-function request(...) end
-
---- Make a HTTP GET request to the given url.
---
--- @tparam string url   The url to request
--- @tparam[opt] { [string] = string } headers Additional headers to send as part
--- of this request.
--- @tparam[opt] boolean binary Whether to make a binary HTTP request. If true,
--- the body will not be UTF-8 encoded, and the received response will not be
--- decoded.
---
--- @tparam[2] {
---   url = string, headers? = { [string] = string },
---   binary? = boolean, method? = string, redirect? = boolean,
--- } request Options for the request. See @{http.request} for details on how
--- these options behave.
---
--- @treturn Response The resulting http response, which can be read from.
--- @treturn[2] nil When the http request failed, such as in the event of a 404
--- error or connection timeout.
--- @treturn string A message detailing why the request failed.
--- @treturn Response|nil The failing http response, if available.
---
--- @changed 1.63 Added argument for headers.
--- @changed 1.80pr1 Response handles are now returned on error if available.
--- @changed 1.80pr1 Added argument for binary handles.
--- @changed 1.80pr1.6 Added support for table argument.
--- @changed 1.86.0 Added PATCH and TRACE methods.
---
--- @usage Make a request to [example.tweaked.cc](https://example.tweaked.cc),
--- and print the returned page.
--- ```lua
--- local request = http.get("https://example.tweaked.cc")
--- print(request.readAll())
--- -- => HTTP is working!
--- request.close()
--- ```
-function get(...) end
-
---- Make a HTTP POST request to the given url.
---
--- @tparam string url   The url to request
--- @tparam string body  The body of the POST request.
--- @tparam[opt] { [string] = string } headers Additional headers to send as part
--- of this request.
--- @tparam[opt] boolean binary Whether to make a binary HTTP request. If true,
--- the body will not be UTF-8 encoded, and the received response will not be
--- decoded.
---
--- @tparam[2] {
---   url = string, body? = string, headers? = { [string] = string },
---   binary? = boolean, method? = string, redirect? = boolean,
--- } request Options for the request. See @{http.request} for details on how
--- these options behave.
---
--- @treturn Response The resulting http response, which can be read from.
--- @treturn[2] nil When the http request failed, such as in the event of a 404
--- error or connection timeout.
--- @treturn string A message detailing why the request failed.
--- @treturn Response|nil The failing http response, if available.
---
--- @since 1.31
--- @changed 1.63 Added argument for headers.
--- @changed 1.80pr1 Response handles are now returned on error if available.
--- @changed 1.80pr1 Added argument for binary handles.
--- @changed 1.80pr1.6 Added support for table argument.
--- @changed 1.86.0 Added PATCH and TRACE methods.
-function post(...) end
-
---- Asynchronously determine whether a URL can be requested.
---
--- If this returns `true`, one should also listen for @{http_check} which will
--- container further information about whether the URL is allowed or not.
---
--- @tparam string url The URL to check.
--- @treturn true When this url is not invalid. This does not imply that it is
--- allowed - see the comment above.
--- @treturn[2] false When this url is invalid.
--- @treturn string A reason why this URL is not valid (for instance, if it is
--- malformed, or blocked).
---
--- @see http.checkURL For a synchronous version.
-function checkURLAsync(url) end
-
---- Determine whether a URL can be requested.
---
--- If this returns `true`, one should also listen for @{http_check} which will
--- container further information about whether the URL is allowed or not.
---
--- @tparam string url The URL to check.
--- @treturn true When this url is valid and can be requested via @{http.request}.
--- @treturn[2] false When this url is invalid.
--- @treturn string A reason why this URL is not valid (for instance, if it is
--- malformed, or blocked).
---
--- @see http.checkURLAsync For an asynchronous version.
---
--- @usage
--- ```lua
--- print(http.checkURL("https://example.tweaked.cc/"))
--- -- => true
--- print(http.checkURL("http://localhost/"))
--- -- => false Domain not permitted
--- print(http.checkURL("not a url"))
--- -- => false URL malformed
--- ```
-function checkURL(url) end
-
---- Open a websocket.
---
--- @tparam string url The websocket url to connect to. This should have the
--- `ws://` or `wss://` protocol.
--- @tparam[opt] { [string] = string } headers Additional headers to send as part
--- of the initial websocket connection.
---
--- @treturn Websocket The websocket connection.
--- @treturn[2] false If the websocket connection failed.
--- @treturn string An error message describing why the connection failed.
--- @since 1.80pr1.1
--- @changed 1.80pr1.3 No longer asynchronous.
--- @changed 1.95.3 Added User-Agent to default headers.
-function websocket(url, headers) end
-
---- Asynchronously open a websocket.
---
--- This returns immediately, a @{websocket_success} or @{websocket_failure}
--- will be queued once the request has completed.
---
--- @tparam string url The websocket url to connect to. This should have the
--- `ws://` or `wss://` protocol.
--- @tparam[opt] { [string] = string } headers Additional headers to send as part
--- of the initial websocket connection.
--- @since 1.80pr1.3
--- @changed 1.95.3 Added User-Agent to default headers.
-function websocketAsync(url, headers) end

gradle.properties

@@ -5,7 +5,7 @@ kotlin.stdlib.default.dependency=false
 kotlin.jvm.target.validation.mode=error
 
 # Mod properties
-modVersion=1.101.0
+modVersion=1.101.2
 
 # Minecraft properties: We want to configure this here so we can read it in settings.gradle
 mcVersion=1.18.2

gradle/libs.versions.toml

@@ -7,7 +7,7 @@ parchment = "2022.03.13"
 parchmentMc = "1.18.2"
 
 autoService = "1.0.1"
-cobalt = { strictly = "[0.5.8,0.6.0)", prefer = "0.5.8" }
+cobalt = "0.6.0"
 jetbrainsAnnotations = "23.0.0"
 kotlin = "1.7.10"
 kotlin-coroutines = "1.6.0"
@@ -23,7 +23,7 @@ checkstyle = "10.3.4"
 curseForgeGradle = "1.0.11"
 forgeGradle = "5.1.+"
 githubRelease = "2.2.12"
-illuaminate = "0.1.0-7-g2a5a89c"
+illuaminate = "0.1.0-20-g8c483a4"
 librarian = "1.+"
 minotaur = "2.+"
 mixinGradle = "0.7.+"

illuaminate.sexp

@@ -111,6 +111,6 @@
   (lint
     (globals
       :max sleep write
-      cct_test describe expect howlci fail it pending stub)))
+      cct_test describe expect howlci fail it pending stub before_each)))
 
 (at /src/web/mount/expr_template.lua (lint (globals :max __expr__)))

src/generated/resources/data/computercraft/recipes/computer_advanced_upgrade.json

@@ -10,7 +10,7 @@
       "tag": "forge:ingots/gold"
     },
     "C": {
-      "item": "computercraft:computer_advanced"
+      "item": "computercraft:computer_normal"
     }
   },
   "result": {

src/generated/resources/data/computercraft/recipes/turtle_advanced_upgrade.json

@@ -10,7 +10,7 @@
       "tag": "forge:ingots/gold"
     },
     "C": {
-      "item": "computercraft:computer_advanced"
+      "item": "computercraft:turtle_normal"
     },
     "B": {
       "tag": "forge:storage_blocks/gold"

src/main/java/dan200/computercraft/client/render/TurtleSmartItemModel.java

@@ -76,6 +76,9 @@ public class TurtleSmartItemModel implements BakedModel
             @Override
             public BakedModel resolve( @Nonnull BakedModel originalModel, @Nonnull ItemStack stack, @Nullable ClientLevel world, @Nullable LivingEntity entity, int random )
             {
+                // Should never happen, but just in case!
+                if ( !(stack.getItem() instanceof ItemTurtle) ) return familyModel;
+
                 ItemTurtle turtle = (ItemTurtle) stack.getItem();
                 int colour = turtle.getColour( stack );
                 ITurtleUpgrade leftUpgrade = turtle.getUpgrade( stack, TurtleSide.LEFT );

src/main/java/dan200/computercraft/core/apis/LuaDateTime.java

@@ -89,7 +89,7 @@ final class LuaDateTime
                             formatter.appendValue( ChronoField.HOUR_OF_DAY, 2 );
                             break;
                         case 'I':
-                            formatter.appendValue( ChronoField.HOUR_OF_AMPM, 2 );
+                            formatter.appendValue( ChronoField.CLOCK_HOUR_OF_AMPM, 2 );
                             break;
                         case 'j':
                             formatter.appendValue( ChronoField.DAY_OF_YEAR, 3 );

src/main/java/dan200/computercraft/core/filesystem/FileSystem.java

@@ -5,6 +5,7 @@
  */
 package dan200.computercraft.core.filesystem;
 
+import com.google.common.base.Splitter;
 import com.google.common.io.ByteStreams;
 import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.filesystem.IFileSystem;
@@ -515,10 +516,11 @@ public class FileSystem
         path = cleanName.toString();
 
         // Collapse the string into its component parts, removing ..'s
-        String[] parts = path.split( "/" );
-        Stack<String> outputParts = new Stack<>();
-        for( String part : parts )
+        ArrayDeque<String> outputParts = new ArrayDeque<>();
+        for( String fullPart : Splitter.on( '/' ).split( path ) )
         {
+            String part = fullPart.trim();
+
             if( part.isEmpty() || part.equals( "." ) || threeDotsPattern.matcher( part ).matches() )
             {
                 // . is redundant
@@ -529,32 +531,32 @@ public class FileSystem
             if( part.equals( ".." ) )
             {
                 // .. can cancel out the last folder entered
-                if( !outputParts.empty() )
+                if( !outputParts.isEmpty() )
                 {
-                    String top = outputParts.peek();
+                    String top = outputParts.peekLast();
                     if( !top.equals( ".." ) )
                     {
-                        outputParts.pop();
+                        outputParts.removeLast();
                     }
                     else
                     {
-                        outputParts.push( ".." );
+                        outputParts.addLast( ".." );
                     }
                 }
                 else
                 {
-                    outputParts.push( ".." );
+                    outputParts.addLast( ".." );
                 }
             }
             else if( part.length() >= 255 )
             {
                 // If part length > 255 and it is the last part
-                outputParts.push( part.substring( 0, 255 ) );
+                outputParts.addLast( part.substring( 0, 255 ).trim() );
             }
             else
             {
                 // Anything else we add to the stack
-                outputParts.push( part );
+                outputParts.addLast( part );
             }
         }
 

src/main/java/dan200/computercraft/data/RecipeGenerator.java

@@ -209,7 +209,7 @@ class RecipeGenerator extends RecipeProvider
             .pattern( "#C#" )
             .pattern( "# #" )
             .define( '#', Tags.Items.INGOTS_GOLD )
-            .define( 'C', Registry.ModItems.COMPUTER_ADVANCED.get() )
+            .define( 'C', Registry.ModItems.COMPUTER_NORMAL.get() )
             .unlockedBy( "has_components", inventoryChange( itemPredicate( Registry.ModItems.COMPUTER_NORMAL.get() ), itemPredicate( Tags.Items.INGOTS_GOLD ) ) )
             .save(
                 RecipeWrapper.wrap( ComputerUpgradeRecipe.SERIALIZER, add ).withExtraData( family( ComputerFamily.ADVANCED ) ),
@@ -255,7 +255,7 @@ class RecipeGenerator extends RecipeProvider
             .pattern( "#C#" )
             .pattern( " B " )
             .define( '#', Tags.Items.INGOTS_GOLD )
-            .define( 'C', Registry.ModItems.COMPUTER_ADVANCED.get() )
+            .define( 'C', Registry.ModItems.TURTLE_NORMAL.get() )
             .define( 'B', Tags.Items.STORAGE_BLOCKS_GOLD )
             .unlockedBy( "has_components", inventoryChange( itemPredicate( Registry.ModItems.TURTLE_NORMAL.get() ), itemPredicate( Tags.Items.INGOTS_GOLD ) ) )
             .save(

src/main/java/dan200/computercraft/shared/peripheral/speaker/DfpwmState.java

@@ -8,7 +8,6 @@ package dan200.computercraft.shared.peripheral.speaker;
 import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.lua.LuaTable;
 import dan200.computercraft.shared.util.PauseAwareTimer;
-import net.minecraft.util.Mth;
 
 import javax.annotation.Nonnull;
 import java.nio.ByteBuffer;
@@ -16,6 +15,7 @@ import java.util.Optional;
 import java.util.concurrent.TimeUnit;
 
 import static dan200.computercraft.shared.peripheral.speaker.SpeakerPeripheral.SAMPLE_RATE;
+import static dan200.computercraft.shared.peripheral.speaker.SpeakerPeripheral.clampVolume;
 
 /**
  * Internal state of the DFPWM decoder and the state of playback.
@@ -87,7 +87,7 @@ class DfpwmState
         buffer.flip();
 
         pendingAudio = buffer;
-        pendingVolume = Mth.clamp( volume.orElse( (double) pendingVolume ).floatValue(), 0.0f, 3.0f );
+        pendingVolume = (float) clampVolume( volume.orElse( (double) pendingVolume ) );
         return true;
     }
 

src/main/java/dan200/computercraft/shared/peripheral/speaker/SpeakerPeripheral.java

@@ -24,6 +24,7 @@ import net.minecraft.network.protocol.game.ClientboundCustomSoundPacket;
 import net.minecraft.resources.ResourceLocation;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.sounds.SoundSource;
+import net.minecraft.util.Mth;
 import net.minecraft.world.level.Level;
 import net.minecraft.world.level.block.state.properties.NoteBlockInstrument;
 import net.minecraft.world.phys.Vec3;
@@ -222,7 +223,7 @@ public abstract class SpeakerPeripheral implements IPeripheral
     @LuaFunction
     public final boolean playNote( ILuaContext context, String instrumentA, Optional<Double> volumeA, Optional<Double> pitchA ) throws LuaException
     {
-        float volume = (float) checkFinite( 1, volumeA.orElse( 1.0 ) );
+        float volume = (float) clampVolume( checkFinite( 1, volumeA.orElse( 1.0 ) ) );
         float pitch = (float) checkFinite( 2, pitchA.orElse( 1.0 ) );
 
         NoteBlockInstrument instrument = null;
@@ -271,7 +272,7 @@ public abstract class SpeakerPeripheral implements IPeripheral
     @LuaFunction
     public final boolean playSound( ILuaContext context, String name, Optional<Double> volumeA, Optional<Double> pitchA ) throws LuaException
     {
-        float volume = (float) checkFinite( 1, volumeA.orElse( 1.0 ) );
+        float volume = (float) clampVolume( checkFinite( 1, volumeA.orElse( 1.0 ) ) );
         float pitch = (float) checkFinite( 2, pitchA.orElse( 1.0 ) );
 
         ResourceLocation identifier;
@@ -396,6 +397,11 @@ public abstract class SpeakerPeripheral implements IPeripheral
         }
     }
 
+    static double clampVolume( double volume )
+    {
+        return Mth.clamp( volume, 0, 3 );
+    }
+
     private record PendingSound(ResourceLocation location, float volume, float pitch)
     {
     }

src/main/resources/data/computercraft/lua/bios.lua

@@ -3,16 +3,15 @@
 -- Ideally we'd use require, but that is part of the shell, and so is not
 -- available to the BIOS or any APIs. All APIs load this using dofile, but that
 -- has not been defined at this point.
-local expect, field
+local expect
 
 do
     local h = fs.open("rom/modules/main/cc/expect.lua", "r")
-    local f, err = loadstring(h.readAll(), "@expect.lua")
+    local f, err = loadstring(h.readAll(), "@/rom/modules/main/cc/expect.lua")
     h.close()
 
     if not f then error(err) end
-    local res = f()
-    expect, field = res.expect, res.field
+    expect = f().expect
 end
 
 if _VERSION == "Lua 5.1" then
@@ -468,7 +467,7 @@ function loadfile(filename, mode, env)
     local file = fs.open(filename, "r")
     if not file then return nil, "File not found" end
 
-    local func, err = load(file.readAll(), "@" .. fs.getName(filename), mode, env)
+    local func, err = load(file.readAll(), "@/" .. fs.combine(filename), mode, env)
     file.close()
     return func, err
 end
@@ -584,257 +583,28 @@ function os.reboot()
     end
 end
 
--- Install the lua part of the HTTP api (if enabled)
-if http then
-    local nativeHTTPRequest = http.request
+local bAPIError = false
 
-    local methods = {
-        GET = true, POST = true, HEAD = true,
-        OPTIONS = true, PUT = true, DELETE = true,
-        PATCH = true, TRACE = true,
-    }
+local function load_apis(dir)
+    if not fs.isDir(dir) then return end
 
-    local function checkKey(options, key, ty, opt)
-        local value = options[key]
-        local valueTy = type(value)
-
-        if (value ~= nil or not opt) and valueTy ~= ty then
-            error(("bad field '%s' (expected %s, got %s"):format(key, ty, valueTy), 4)
-        end
-    end
-
-    local function checkOptions(options, body)
-        checkKey(options, "url", "string")
-        if body == false then
-          checkKey(options, "body", "nil")
-        else
-          checkKey(options, "body", "string", not body)
-        end
-        checkKey(options, "headers", "table", true)
-        checkKey(options, "method", "string", true)
-        checkKey(options, "redirect", "boolean", true)
-
-        if options.method and not methods[options.method] then
-            error("Unsupported HTTP method", 3)
-        end
-    end
-
-    local function wrapRequest(_url, ...)
-        local ok, err = nativeHTTPRequest(...)
-        if ok then
-            while true do
-                local event, param1, param2, param3 = os.pullEvent()
-                if event == "http_success" and param1 == _url then
-                    return param2
-                elseif event == "http_failure" and param1 == _url then
-                    return nil, param2, param3
+    for _, file in ipairs(fs.list(dir)) do
+        if file:sub(1, 1) ~= "." then
+            local path = fs.combine(dir, file)
+            if not fs.isDir(path) then
+                if not os.loadAPI(path) then
+                    bAPIError = true
                 end
             end
         end
-        return nil, err
     end
-
-    http.get = function(_url, _headers, _binary)
-        if type(_url) == "table" then
-            checkOptions(_url, false)
-            return wrapRequest(_url.url, _url)
-        end
-
-        expect(1, _url, "string")
-        expect(2, _headers, "table", "nil")
-        expect(3, _binary, "boolean", "nil")
-        return wrapRequest(_url, _url, nil, _headers, _binary)
-    end
-
-    http.post = function(_url, _post, _headers, _binary)
-        if type(_url) == "table" then
-            checkOptions(_url, true)
-            return wrapRequest(_url.url, _url)
-        end
-
-        expect(1, _url, "string")
-        expect(2, _post, "string")
-        expect(3, _headers, "table", "nil")
-        expect(4, _binary, "boolean", "nil")
-        return wrapRequest(_url, _url, _post, _headers, _binary)
-    end
-
-    http.request = function(_url, _post, _headers, _binary)
-        local url
-        if type(_url) == "table" then
-            checkOptions(_url)
-            url = _url.url
-        else
-            expect(1, _url, "string")
-            expect(2, _post, "string", "nil")
-            expect(3, _headers, "table", "nil")
-            expect(4, _binary, "boolean", "nil")
-            url = _url.url
-        end
-
-        local ok, err = nativeHTTPRequest(_url, _post, _headers, _binary)
-        if not ok then
-            os.queueEvent("http_failure", url, err)
-        end
-        return ok, err
-    end
-
-    local nativeCheckURL = http.checkURL
-    http.checkURLAsync = nativeCheckURL
-    http.checkURL = function(_url)
-        expect(1, _url, "string")
-        local ok, err = nativeCheckURL(_url)
-        if not ok then return ok, err end
-
-        while true do
-            local _, url, ok, err = os.pullEvent("http_check")
-            if url == _url then return ok, err end
-        end
-    end
-
-    local nativeWebsocket = http.websocket
-    http.websocketAsync = nativeWebsocket
-    http.websocket = function(_url, _headers)
-        expect(1, _url, "string")
-        expect(2, _headers, "table", "nil")
-
-        local ok, err = nativeWebsocket(_url, _headers)
-        if not ok then return ok, err end
-
-        while true do
-            local event, url, param = os.pullEvent( )
-            if event == "websocket_success" and url == _url then
-                return param
-            elseif event == "websocket_failure" and url == _url then
-                return false, param
-            end
-        end
-    end
-end
-
--- Install the lua part of the FS api
-local tEmpty = {}
-function fs.complete(sPath, sLocation, bIncludeFiles, bIncludeDirs)
-    expect(1, sPath, "string")
-    expect(2, sLocation, "string")
-    local bIncludeHidden = nil
-    if type(bIncludeFiles) == "table" then
-        bIncludeDirs = field(bIncludeFiles, "include_dirs", "boolean", "nil")
-        bIncludeHidden = field(bIncludeFiles, "include_hidden", "boolean", "nil")
-        bIncludeFiles = field(bIncludeFiles, "include_files", "boolean", "nil")
-    else
-        expect(3, bIncludeFiles, "boolean", "nil")
-        expect(4, bIncludeDirs, "boolean", "nil")
-    end
-
-    bIncludeHidden = bIncludeHidden ~= false
-    bIncludeFiles = bIncludeFiles ~= false
-    bIncludeDirs = bIncludeDirs ~= false
-    local sDir = sLocation
-    local nStart = 1
-    local nSlash = string.find(sPath, "[/\\]", nStart)
-    if nSlash == 1 then
-        sDir = ""
-        nStart = 2
-    end
-    local sName
-    while not sName do
-        local nSlash = string.find(sPath, "[/\\]", nStart)
-        if nSlash then
-            local sPart = string.sub(sPath, nStart, nSlash - 1)
-            sDir = fs.combine(sDir, sPart)
-            nStart = nSlash + 1
-        else
-            sName = string.sub(sPath, nStart)
-        end
-    end
-
-    if fs.isDir(sDir) then
-        local tResults = {}
-        if bIncludeDirs and sPath == "" then
-            table.insert(tResults, ".")
-        end
-        if sDir ~= "" then
-            if sPath == "" then
-                table.insert(tResults, bIncludeDirs and ".." or "../")
-            elseif sPath == "." then
-                table.insert(tResults, bIncludeDirs and "." or "./")
-            end
-        end
-        local tFiles = fs.list(sDir)
-        for n = 1, #tFiles do
-            local sFile = tFiles[n]
-            if #sFile >= #sName and string.sub(sFile, 1, #sName) == sName and (
-                bIncludeHidden or sFile:sub(1, 1) ~= "." or sName:sub(1, 1) == "."
-            ) then
-                local bIsDir = fs.isDir(fs.combine(sDir, sFile))
-                local sResult = string.sub(sFile, #sName + 1)
-                if bIsDir then
-                    table.insert(tResults, sResult .. "/")
-                    if bIncludeDirs and #sResult > 0 then
-                        table.insert(tResults, sResult)
-                    end
-                else
-                    if bIncludeFiles and #sResult > 0 then
-                        table.insert(tResults, sResult)
-                    end
-                end
-            end
-        end
-        return tResults
-    end
-    return tEmpty
-end
-
-function fs.isDriveRoot(sPath)
-    expect(1, sPath, "string")
-    -- Force the root directory to be a mount.
-    return fs.getDir(sPath) == ".." or fs.getDrive(sPath) ~= fs.getDrive(fs.getDir(sPath))
 end
 
 -- Load APIs
-local bAPIError = false
-local tApis = fs.list("rom/apis")
-for _, sFile in ipairs(tApis) do
-    if string.sub(sFile, 1, 1) ~= "." then
-        local sPath = fs.combine("rom/apis", sFile)
-        if not fs.isDir(sPath) then
-            if not os.loadAPI(sPath) then
-                bAPIError = true
-            end
-        end
-    end
-end
-
-if turtle and fs.isDir("rom/apis/turtle") then
-    -- Load turtle APIs
-    local tApis = fs.list("rom/apis/turtle")
-    for _, sFile in ipairs(tApis) do
-        if string.sub(sFile, 1, 1) ~= "." then
-            local sPath = fs.combine("rom/apis/turtle", sFile)
-            if not fs.isDir(sPath) then
-                if not os.loadAPI(sPath) then
-                    bAPIError = true
-                end
-            end
-        end
-    end
-end
-
-if pocket and fs.isDir("rom/apis/pocket") then
-    -- Load pocket APIs
-    local tApis = fs.list("rom/apis/pocket")
-    for _, sFile in ipairs(tApis) do
-        if string.sub(sFile, 1, 1) ~= "." then
-            local sPath = fs.combine("rom/apis/pocket", sFile)
-            if not fs.isDir(sPath) then
-                if not os.loadAPI(sPath) then
-                    bAPIError = true
-                end
-            end
-        end
-    end
-end
+load_apis("rom/apis")
+if http then load_apis("rom/apis/http") end
+if turtle then load_apis("rom/apis/turtle") end
+if pocket then load_apis("rom/apis/pocket") end
 
 if commands and fs.isDir("rom/apis/command") then
     -- Load command APIs
@@ -930,7 +700,7 @@ settings.define("motd.path", {
 
 settings.define("lua.warn_against_use_of_local", {
     default = true,
-    description = [[Print a message when input in the Lua REPL starts with the word 'local'. Local variables defined in the Lua REPL are be inaccessable on the next input.]],
+    description = [[Print a message when input in the Lua REPL starts with the word 'local'. Local variables defined in the Lua REPL are be inaccessible on the next input.]],
     type = "boolean",
 })
 settings.define("lua.function_args", {

src/main/resources/data/computercraft/lua/rom/apis/fs.lua

@@ -0,0 +1,147 @@
+--- @module fs
+
+local expect = dofile("rom/modules/main/cc/expect.lua")
+local expect, field = expect.expect, expect.field
+
+local native = fs
+
+local fs = _ENV
+for k, v in pairs(native) do fs[k] = v end
+
+--[[- Provides completion for a file or directory name, suitable for use with
+@{_G.read}.
+
+When a directory is a possible candidate for completion, two entries are
+included - one with a trailing slash (indicating that entries within this
+directory exist) and one without it (meaning this entry is an immediate
+completion candidate). `include_dirs` can be set to @{false} to only include
+those with a trailing slash.
+
+@tparam[1] string path The path to complete.
+@tparam[1] string location The location where paths are resolved from.
+@tparam[1,opt=true] boolean include_files When @{false}, only directories will
+be included in the returned list.
+@tparam[1,opt=true] boolean include_dirs When @{false}, "raw" directories will
+not be included in the returned list.
+
+@tparam[2] string path The path to complete.
+@tparam[2] string location The location where paths are resolved from.
+@tparam[2] {
+    include_dirs? = boolean, include_files? = boolean,
+    include_hidden? = boolean
+} options
+This table form is an expanded version of the previous syntax. The
+`include_files` and `include_dirs` arguments from above are passed in as fields.
+
+This table also accepts the following options:
+ - `include_hidden`: Whether to include hidden files (those starting with `.`)
+   by default. They will still be shown when typing a `.`.
+
+@treturn { string... } A list of possible completion candidates.
+@since 1.74
+@changed 1.101.0
+@usage Complete files in the root directory.
+
+    read(nil, nil, function(str)
+        return fs.complete(str, "", true, false)
+    end)
+
+@usage Complete files in the root directory, hiding hidden files by default.
+
+    read(nil, nil, function(str)
+        return fs.complete(str, "", {
+            include_files = true,
+            include_dirs = false,
+            include_hidden = false,
+        })
+    end)
+]]
+function fs.complete(sPath, sLocation, bIncludeFiles, bIncludeDirs)
+    expect(1, sPath, "string")
+    expect(2, sLocation, "string")
+    local bIncludeHidden = nil
+    if type(bIncludeFiles) == "table" then
+        bIncludeDirs = field(bIncludeFiles, "include_dirs", "boolean", "nil")
+        bIncludeHidden = field(bIncludeFiles, "include_hidden", "boolean", "nil")
+        bIncludeFiles = field(bIncludeFiles, "include_files", "boolean", "nil")
+    else
+        expect(3, bIncludeFiles, "boolean", "nil")
+        expect(4, bIncludeDirs, "boolean", "nil")
+    end
+
+    bIncludeHidden = bIncludeHidden ~= false
+    bIncludeFiles = bIncludeFiles ~= false
+    bIncludeDirs = bIncludeDirs ~= false
+    local sDir = sLocation
+    local nStart = 1
+    local nSlash = string.find(sPath, "[/\\]", nStart)
+    if nSlash == 1 then
+        sDir = ""
+        nStart = 2
+    end
+    local sName
+    while not sName do
+        local nSlash = string.find(sPath, "[/\\]", nStart)
+        if nSlash then
+            local sPart = string.sub(sPath, nStart, nSlash - 1)
+            sDir = fs.combine(sDir, sPart)
+            nStart = nSlash + 1
+        else
+            sName = string.sub(sPath, nStart)
+        end
+    end
+
+    if fs.isDir(sDir) then
+        local tResults = {}
+        if bIncludeDirs and sPath == "" then
+            table.insert(tResults, ".")
+        end
+        if sDir ~= "" then
+            if sPath == "" then
+                table.insert(tResults, bIncludeDirs and ".." or "../")
+            elseif sPath == "." then
+                table.insert(tResults, bIncludeDirs and "." or "./")
+            end
+        end
+        local tFiles = fs.list(sDir)
+        for n = 1, #tFiles do
+            local sFile = tFiles[n]
+            if #sFile >= #sName and string.sub(sFile, 1, #sName) == sName and (
+                bIncludeHidden or sFile:sub(1, 1) ~= "." or sName:sub(1, 1) == "."
+            ) then
+                local bIsDir = fs.isDir(fs.combine(sDir, sFile))
+                local sResult = string.sub(sFile, #sName + 1)
+                if bIsDir then
+                    table.insert(tResults, sResult .. "/")
+                    if bIncludeDirs and #sResult > 0 then
+                        table.insert(tResults, sResult)
+                    end
+                else
+                    if bIncludeFiles and #sResult > 0 then
+                        table.insert(tResults, sResult)
+                    end
+                end
+            end
+        end
+        return tResults
+    end
+
+    return {}
+end
+
+--- Returns true if a path is mounted to the parent filesystem.
+--
+-- The root filesystem "/" is considered a mount, along with disk folders and
+-- the rom folder. Other programs (such as network shares) can exstend this to
+-- make other mount types by correctly assigning their return value for getDrive.
+--
+-- @tparam string path The path to check.
+-- @treturn boolean If the path is mounted, rather than a normal file/folder.
+-- @throws If the path does not exist.
+-- @see getDrive
+-- @since 1.87.0
+function fs.isDriveRoot(sPath)
+    expect(1, sPath, "string")
+    -- Force the root directory to be a mount.
+    return fs.getDir(sPath) == ".." or fs.getDrive(sPath) ~= fs.getDrive(fs.getDir(sPath))
+end

src/main/resources/data/computercraft/lua/rom/apis/help.lua

@@ -16,7 +16,7 @@ function path()
     return sPath
 end
 
---- Sets the colon-seperated list of directories where help files are searched
+--- Sets the colon-separated list of directories where help files are searched
 -- for to `newPath`
 --
 -- @tparam string newPath The new path to use.

src/main/resources/data/computercraft/lua/rom/apis/http/http.lua

@@ -0,0 +1,317 @@
+--[[- Make HTTP requests, sending and receiving data to a remote web server.
+
+@module http
+@since 1.1
+@see local_ips To allow accessing servers running on your local network.
+]]
+
+local expect = dofile("rom/modules/main/cc/expect.lua").expect
+
+local native = http
+local nativeHTTPRequest = http.request
+
+local methods = {
+    GET = true, POST = true, HEAD = true,
+    OPTIONS = true, PUT = true, DELETE = true,
+    PATCH = true, TRACE = true,
+}
+
+local function checkKey(options, key, ty, opt)
+    local value = options[key]
+    local valueTy = type(value)
+
+    if (value ~= nil or not opt) and valueTy ~= ty then
+        error(("bad field '%s' (expected %s, got %s"):format(key, ty, valueTy), 4)
+    end
+end
+
+local function checkOptions(options, body)
+    checkKey(options, "url", "string")
+    if body == false then
+        checkKey(options, "body", "nil")
+    else
+        checkKey(options, "body", "string", not body)
+    end
+    checkKey(options, "headers", "table", true)
+    checkKey(options, "method", "string", true)
+    checkKey(options, "redirect", "boolean", true)
+
+    if options.method and not methods[options.method] then
+        error("Unsupported HTTP method", 3)
+    end
+end
+
+local function wrapRequest(_url, ...)
+    local ok, err = nativeHTTPRequest(...)
+    if ok then
+        while true do
+            local event, param1, param2, param3 = os.pullEvent()
+            if event == "http_success" and param1 == _url then
+                return param2
+            elseif event == "http_failure" and param1 == _url then
+                return nil, param2, param3
+            end
+        end
+    end
+    return nil, err
+end
+
+--[[- Make a HTTP GET request to the given url.
+
+@tparam string url   The url to request
+@tparam[opt] { [string] = string } headers Additional headers to send as part
+of this request.
+@tparam[opt] boolean binary Whether to make a binary HTTP request. If true,
+the body will not be UTF-8 encoded, and the received response will not be
+decoded.
+
+@tparam[2] {
+  url = string, headers? = { [string] = string },
+  binary? = boolean, method? = string, redirect? = boolean,
+} request Options for the request. See @{http.request} for details on how
+these options behave.
+
+@treturn Response The resulting http response, which can be read from.
+@treturn[2] nil When the http request failed, such as in the event of a 404
+error or connection timeout.
+@treturn string A message detailing why the request failed.
+@treturn Response|nil The failing http response, if available.
+
+@changed 1.63 Added argument for headers.
+@changed 1.80pr1 Response handles are now returned on error if available.
+@changed 1.80pr1 Added argument for binary handles.
+@changed 1.80pr1.6 Added support for table argument.
+@changed 1.86.0 Added PATCH and TRACE methods.
+
+@usage Make a request to [example.tweaked.cc](https://example.tweaked.cc),
+and print the returned page.
+
+```lua
+local request = http.get("https://example.tweaked.cc")
+print(request.readAll())
+-- => HTTP is working!
+request.close()
+```
+]]
+function get(_url, _headers, _binary)
+    if type(_url) == "table" then
+        checkOptions(_url, false)
+        return wrapRequest(_url.url, _url)
+    end
+
+    expect(1, _url, "string")
+    expect(2, _headers, "table", "nil")
+    expect(3, _binary, "boolean", "nil")
+    return wrapRequest(_url, _url, nil, _headers, _binary)
+end
+
+--[[- Make a HTTP POST request to the given url.
+
+@tparam string url   The url to request
+@tparam string body  The body of the POST request.
+@tparam[opt] { [string] = string } headers Additional headers to send as part
+of this request.
+@tparam[opt] boolean binary Whether to make a binary HTTP request. If true,
+the body will not be UTF-8 encoded, and the received response will not be
+decoded.
+
+@tparam[2] {
+  url = string, body? = string, headers? = { [string] = string },
+  binary? = boolean, method? = string, redirect? = boolean,
+} request Options for the request. See @{http.request} for details on how
+these options behave.
+
+@treturn Response The resulting http response, which can be read from.
+@treturn[2] nil When the http request failed, such as in the event of a 404
+error or connection timeout.
+@treturn string A message detailing why the request failed.
+@treturn Response|nil The failing http response, if available.
+
+@since 1.31
+@changed 1.63 Added argument for headers.
+@changed 1.80pr1 Response handles are now returned on error if available.
+@changed 1.80pr1 Added argument for binary handles.
+@changed 1.80pr1.6 Added support for table argument.
+@changed 1.86.0 Added PATCH and TRACE methods.
+]]
+function post(_url, _post, _headers, _binary)
+    if type(_url) == "table" then
+        checkOptions(_url, true)
+        return wrapRequest(_url.url, _url)
+    end
+
+    expect(1, _url, "string")
+    expect(2, _post, "string")
+    expect(3, _headers, "table", "nil")
+    expect(4, _binary, "boolean", "nil")
+    return wrapRequest(_url, _url, _post, _headers, _binary)
+end
+
+--[[- Asynchronously make a HTTP request to the given url.
+
+This returns immediately, a @{http_success} or @{http_failure} will be queued
+once the request has completed.
+
+@tparam      string url   The url to request
+@tparam[opt] string body  An optional string containing the body of the
+request. If specified, a `POST` request will be made instead.
+@tparam[opt] { [string] = string } headers Additional headers to send as part
+of this request.
+@tparam[opt] boolean binary Whether to make a binary HTTP request. If true,
+the body will not be UTF-8 encoded, and the received response will not be
+decoded.
+
+@tparam[2] {
+  url = string, body? = string, headers? = { [string] = string },
+  binary? = boolean, method? = string, redirect? = boolean,
+} request Options for the request.
+
+This table form is an expanded version of the previous syntax. All arguments
+from above are passed in as fields instead (for instance,
+`http.request("https://example.com")` becomes `http.request { url =
+"https://example.com" }`).
+ This table also accepts several additional options:
+
+ - `method`: Which HTTP method to use, for instance `"PATCH"` or `"DELETE"`.
+ - `redirect`: Whether to follow HTTP redirects. Defaults to true.
+
+@see http.get  For a synchronous way to make GET requests.
+@see http.post For a synchronous way to make POST requests.
+
+@changed 1.63 Added argument for headers.
+@changed 1.80pr1 Added argument for binary handles.
+@changed 1.80pr1.6 Added support for table argument.
+@changed 1.86.0 Added PATCH and TRACE methods.
+]]
+function request(_url, _post, _headers, _binary)
+    local url
+    if type(_url) == "table" then
+        checkOptions(_url)
+        url = _url.url
+    else
+        expect(1, _url, "string")
+        expect(2, _post, "string", "nil")
+        expect(3, _headers, "table", "nil")
+        expect(4, _binary, "boolean", "nil")
+        url = _url
+    end
+
+    local ok, err = nativeHTTPRequest(_url, _post, _headers, _binary)
+    if not ok then
+        os.queueEvent("http_failure", url, err)
+    end
+
+    -- Return true/false for legacy reasons. Undocumented, as it shouldn't be relied on.
+    return ok, err
+end
+
+local nativeCheckURL = native.checkURL
+
+--[[- Asynchronously determine whether a URL can be requested.
+
+If this returns `true`, one should also listen for @{http_check} which will
+container further information about whether the URL is allowed or not.
+
+@tparam string url The URL to check.
+@treturn true When this url is not invalid. This does not imply that it is
+allowed - see the comment above.
+@treturn[2] false When this url is invalid.
+@treturn string A reason why this URL is not valid (for instance, if it is
+malformed, or blocked).
+
+@see http.checkURL For a synchronous version.
+]]
+checkURLAsync = nativeCheckURL
+
+--[[- Determine whether a URL can be requested.
+
+If this returns `true`, one should also listen for @{http_check} which will
+container further information about whether the URL is allowed or not.
+
+@tparam string url The URL to check.
+@treturn true When this url is valid and can be requested via @{http.request}.
+@treturn[2] false When this url is invalid.
+@treturn string A reason why this URL is not valid (for instance, if it is
+malformed, or blocked).
+
+@see http.checkURLAsync For an asynchronous version.
+
+@usage
+```lua
+print(http.checkURL("https://example.tweaked.cc/"))
+-- => true
+print(http.checkURL("http://localhost/"))
+-- => false Domain not permitted
+print(http.checkURL("not a url"))
+-- => false URL malformed
+```
+]]
+function checkURL(_url)
+    expect(1, _url, "string")
+    local ok, err = nativeCheckURL(_url)
+    if not ok then return ok, err end
+
+    while true do
+        local _, url, ok, err = os.pullEvent("http_check")
+        if url == _url then return ok, err end
+    end
+end
+
+local nativeWebsocket = native.websocket
+
+
+--[[- Asynchronously open a websocket.
+
+This returns immediately, a @{websocket_success} or @{websocket_failure}
+will be queued once the request has completed.
+
+@tparam string url The websocket url to connect to. This should have the
+`ws://` or `wss://` protocol.
+@tparam[opt] { [string] = string } headers Additional headers to send as part
+of the initial websocket connection.
+@since 1.80pr1.3
+@changed 1.95.3 Added User-Agent to default headers.
+]]
+function websocketAsync(url, headers)
+    expect(1, url, "string")
+    expect(2, headers, "table", "nil")
+
+    local ok, err = nativeWebsocket(url, headers)
+    if not ok then
+        os.queueEvent("websocket_failure", url, err)
+    end
+
+    -- Return true/false for legacy reasons. Undocumented, as it shouldn't be relied on.
+    return ok, err
+end
+
+--[[- Open a websocket.
+
+@tparam string url The websocket url to connect to. This should have the
+`ws://` or `wss://` protocol.
+@tparam[opt] { [string] = string } headers Additional headers to send as part
+of the initial websocket connection.
+
+@treturn Websocket The websocket connection.
+@treturn[2] false If the websocket connection failed.
+@treturn string An error message describing why the connection failed.
+@since 1.80pr1.1
+@changed 1.80pr1.3 No longer asynchronous.
+@changed 1.95.3 Added User-Agent to default headers.
+]]
+function websocket(_url, _headers)
+    expect(1, _url, "string")
+    expect(2, _headers, "table", "nil")
+
+    local ok, err = nativeWebsocket(_url, _headers)
+    if not ok then return ok, err end
+
+    while true do
+        local event, url, param = os.pullEvent( )
+        if event == "websocket_success" and url == _url then
+            return param
+        elseif event == "websocket_failure" and url == _url then
+            return false, param
+        end
+    end
+end

src/main/resources/data/computercraft/lua/rom/apis/parallel.lua

@@ -1,6 +1,6 @@
 --[[- A simple way to run several functions at once.
 
-Functions are not actually executed simultaniously, but rather this API will
+Functions are not actually executed simultaneously, but rather this API will
 automatically switch between them whenever they yield (e.g. whenever they call
 @{coroutine.yield}, or functions that call that - such as @{os.pullEvent} - or
 functions that call that, etc - basically, anything that causes the function

src/main/resources/data/computercraft/lua/rom/apis/peripheral.lua

@@ -17,12 +17,13 @@ You can list the names of all peripherals with the `peripherals` program, or the
 @{peripheral.getNames} function.
 
 It's also possible to use peripherals which are further away from your computer
-through the use of @{modem|Wired Modems}. Place one modem against your computer,
-run Networking Cable to your peripheral, and then place another modem against
-that block. You can then right click the modem to use (or *attach*) the
-peripheral. This will print a peripheral name to chat, which can then be used
-just like a direction name to access the peripheral. You can click on the message
-to copy the name to your clipboard.
+through the use of @{modem|Wired Modems}. Place one modem against your computer
+(you may need to sneak and right click), run Networking Cable to your
+peripheral, and then place another modem against that block. You can then right
+click the modem to use (or *attach*) the peripheral. This will print a
+peripheral name to chat, which can then be used just like a direction name to
+access the peripheral. You can click on the message to copy the name to your
+clipboard.
 
 ## Using peripherals
 

src/main/resources/data/computercraft/lua/rom/apis/rednet.lua

@@ -193,7 +193,7 @@ function send(recipient, message, protocol)
     local sent = false
     if recipient == os.getComputerID() then
         -- Loopback to ourselves
-        os.queueEvent("rednet_message", os.getComputerID(), message_wrapper, protocol)
+        os.queueEvent("rednet_message", os.getComputerID(), message, protocol)
         sent = true
     else
         -- Send on all open modems, to the target and to repeaters
@@ -217,9 +217,10 @@ end
 channel. The message will be received by every device listening to rednet.
 
 @param message The message to send. This should not contain coroutines or
-functions, as they will be converted to @{nil}.  @tparam[opt] string protocol
-The "protocol" to send this message under. When using @{rednet.receive} one can
-filter to only receive messages sent under a particular protocol.
+functions, as they will be converted to @{nil}.
+@tparam[opt] string protocol The "protocol" to send this message under. When
+using @{rednet.receive} one can filter to only receive messages sent under a
+particular protocol.
 @see rednet.receive
 @changed 1.6 Added protocol parameter.
 @usage Broadcast the words "Hello, world!" to every computer using rednet.
@@ -318,7 +319,7 @@ different, or if they only join a given network after "registering" themselves
 before doing so (eg while offline or part of a different network).
 
 @tparam string protocol The protocol this computer provides.
-@tparam string hostname The name this protocol exposes for the given protocol.
+@tparam string hostname The name this computer exposes for the given protocol.
 @throws If trying to register a hostname which is reserved, or currently in use.
 @see rednet.unhost
 @see rednet.lookup
@@ -463,6 +464,7 @@ function run()
             if channel == id_as_channel() or channel == CHANNEL_BROADCAST then
                 if type(message) == "table" and type(message.nMessageID) == "number"
                     and message.nMessageID == message.nMessageID and not received_messages[message.nMessageID]
+                    and (type(message.nSender) == "nil" or (type(message.nSender) == "number" and message.nSender == message.nSender))
                     and ((message.nRecipient and message.nRecipient == os.getComputerID()) or channel == CHANNEL_BROADCAST)
                     and isOpen(modem)
                 then

src/main/resources/data/computercraft/lua/rom/apis/textutils.lua

@@ -157,7 +157,7 @@ function pagedPrint(text, free_lines)
     -- Removed the redirector
     term.redirect(oldTerm)
 
-    -- Propogate errors
+    -- Propagate errors
     if not ok then
         error(err, 0)
     end

src/main/resources/data/computercraft/lua/rom/apis/turtle/turtle.lua

@@ -6,7 +6,7 @@ end
 
 --- The builtin turtle API, without any generated helper functions.
 --
--- @deprecated Historically this table behaved differently to the main turtle API, but this is no longer the base. You
+-- @deprecated Historically this table behaved differently to the main turtle API, but this is no longer the case. You
 -- should not need to use it.
 native = turtle.native or turtle
 

src/main/resources/data/computercraft/lua/rom/help/changelog.md

@@ -1,18 +1,31 @@
+# New features in CC: Tweaked 1.101.2
+
+* Error messages in `edit` are now displayed in red on advanced computers.
+* Improvements to the display of errors in the shell and REPL.
+
+Several bug fixes:
+* Fix `import.lua` failing to upload a file.
+* Fix several issues with sparse Lua tables (Shiranuit).
+* Computer upgrades now accept normal computers, rather than uselessly allowing you to upgrade an advanced computer to an advanced computer!
+* Correctly clamp speaker volume.
+* Fix rednet queueing the wrong message when sending a message to the current computer.
+* Fix the Lua VM crashing when a `__len` metamethod yields.
+* Trim spaces from filesystem paths.
+* Correctly format 12AM/PM with `%I`.
+
 # New features in CC: Tweaked 1.101.0
 
 * Improve Dutch translation (Quezler)
 * Better reporting of fatal computer timeouts in the server log.
 * Convert detail providers into a registry, allowing peripheral mods to read item/block details.
 * Redesign the metrics system. `/computercraft track` now allows computing aggregates (total, max, avg) on any metric, not just computer time.
-* File drag-and-drop now queues a `file_transfer` event on the computer. The
-  built-in shell or the `import` program must now be running to upload files.
+* File drag-and-drop now queues a `file_transfer` event on the computer. The built-in shell or the `import` program must now be running to upload files.
 * The `peripheral` now searches for remote peripherals using any peripheral with the `peripheral_hub` type, not just wired modems.
-* Add `include_hidden` option to `fs.complete`, which can be used to prevent hidden files showing up in autocomplete results. (IvoLeal72)
+* Add `include_hidden` option to `fs.complete`, which can be used to prevent hidden files showing up in autocomplete results. (IvoLeal72).
 * Add `shell.autocomplete_hidden` setting. (IvoLeal72)
 
 Several bug fixes:
-* Prevent `edit`'s "Run" command scrolling the terminal output on smaller
-  screens.
+* Prevent `edit`'s "Run" command scrolling the terminal output on smaller screens.
 * Remove some non-determinism in computing item's `nbt` hash.
 * Don't set the `Origin` header on outgoing websocket requests.
 
@@ -182,8 +195,7 @@ And several bug fixes:
 * Prevent `parallel.*` from hanging when no arguments are given.
 * Prevent issue in rednet when the message ID is NaN.
 * Fix `help` program crashing when terminal changes width.
-* Ensure monitors are well-formed when placed, preventing graphical glitches
-  when using Carry On or Quark.
+* Ensure monitors are well-formed when placed, preventing graphical glitches when using Carry On or Quark.
 * Accept several more extensions in the websocket client.
 * Prevent `wget` crashing when given an invalid URL and no filename.
 * Correctly wrap string within `textutils.slowWrite`.
@@ -210,7 +222,7 @@ And several bug fixes:
 
 And several bug fixes:
 * Fix NPE when using a treasure disk when no treasure disks are available.
-* Prevent command computers discarding command ouput when certain game rules are off.
+* Prevent command computers discarding command output when certain game rules are off.
 * Fix turtles not updating peripherals when upgrades are unequipped (Ronan-H).
 * Fix computers not shutting down on fatal errors within the Lua VM.
 * Speakers now correctly stop playing when broken, and sound follows noisy turtles and pocket computers.
@@ -220,32 +232,6 @@ And several bug fixes:
 * Correctly render the transparent background on pocket/normal computers.
 * Don't apply CraftTweaker actions twice on single-player worlds.
 
-# New features in CC: Tweaked 1.97.0
-
-* Update several translations (Anavrins, Jummit, Naheulf).
-* Add button to view a computer's folder to `/computercraft dump`.
-* Allow cleaning dyed turtles in a cauldron.
-* Add scale subcommand to `monitor` program (MCJack123).
-* Add option to make `textutils.serialize` not write an indent (magiczocker10).
-* Allow comparing vectors using `==` (fatboychummy).
-* Improve HTTP error messages for SSL failures.
-* Allow `craft` program to craft unlimited items (fatboychummy).
-* Impose some limits on various command queues.
-* Add buttons to shutdown and terminate to computer GUIs.
-* Add program subcompletion to several programs (Wojbie).
-* Update the `help` program to accept and (partially) highlight markdown files.
-* Remove config option for the debug API.
-* Allow setting the subprotocol header for websockets.
-
-And several bug fixes:
-* Fix NPE when using a treasure disk when no treasure disks are available.
-* Prevent command computers discarding command ouput when certain game rules are off.
-* Fix turtles not updating peripherals when upgrades are unequipped (Ronan-H).
-* Fix computers not shutting down on fatal errors within the Lua VM.
-* Speakers now correctly stop playing when broken, and sound follows noisy turtles and pocket computers.
-* Update the `wget` to be more resiliant in the face of user-errors.
-* Fix exiting `paint` typing "e" in the shell.
-
 # New features in CC: Tweaked 1.96.0
 
 * Use lightGrey for folders within the "list" program.
@@ -297,7 +283,7 @@ Several bug fixes:
 # New features in CC: Tweaked 1.95.0
 
 * Optimise the paint program's initial render.
-* Several documentation improvments (Gibbo3771, MCJack123).
+* Several documentation improvements (Gibbo3771, MCJack123).
 * `fs.combine` now accepts multiple arguments.
 * Add a setting (`bios.strict_globals`) to error when accidentally declaring a global. (Lupus590).
 * Add an improved help viewer which allows scrolling up and down (MCJack123).
@@ -337,7 +323,7 @@ And several bug fixes:
 
 * Update Swedish translations (Granddave).
 * Printers use item tags to check dyes.
-* HTTP rules may now be targetted for a specific port.
+* HTTP rules may now be targeted for a specific port.
 * Don't propagate adjacent redstone signals through computers.
 
 And several bug fixes:
@@ -361,7 +347,7 @@ And several bug fixes:
 # New features in CC: Tweaked 1.91.0
 
 * [Generic peripherals] Expose NBT hashes of items to inventory methods.
-* Bump Cobalt version
+* Bump Cobalt version:
   * Optimise handling of string concatenation.
   * Add string.{pack,unpack,packsize} (MCJack123)
 * Update to 1.16.2
@@ -457,7 +443,7 @@ And several bug fixes:
   - Add `utf8` lib.
   - Mirror Lua's behaviour of tail calls more closely. Native functions are no longer tail called, and tail calls are displayed in the stack trace.
   - `table.unpack` now uses `__len` and `__index` metamethods.
-  - Parser errors now include the token where the error occured.
+  - Parser errors now include the token where the error occurred.
 * Add `textutils.unserializeJSON`. This can be used to decode standard JSON and stringified-NBT.
 * The `settings` API now allows "defining" settings. This allows settings to specify a default value and description.
 * Enable the motd on non-pocket computers.
@@ -465,7 +451,7 @@ And several bug fixes:
 * Add Danish and Korean translations (ChristianLW, mindy15963)
 * Fire `mouse_up` events in the monitor program.
 * Allow specifying a timeout to `websocket.receive`.
-* Increase the maximimum limit for websocket messages.
+* Increase the maximum limit for websocket messages.
 * Optimise capacity checking of computer/disk folders.
 
 And several bug fixes:
@@ -477,13 +463,12 @@ And several bug fixes:
 
 # New features in CC: Tweaked 1.86.2
 
-* Fix peripheral.getMethods returning an empty table
-* Update to Minecraft 1.15.2. This is currently alpha-quality and so is missing
-  missing features and may be unstable.
+* Fix peripheral.getMethods returning an empty table.
+* Update to Minecraft 1.15.2. This is currently alpha-quality and so is missing missing features and may be unstable.
 
 # New features in CC: Tweaked 1.86.1
 
-* Add a help message to the Lua REPL's exit function
+* Add a help message to the Lua REPL's exit function.
 * Add more MOTD messages. (osmarks)
 * GPS requests are now made anonymously (osmarks)
 * Minor memory usage improvements to Cobalt VM.

src/main/resources/data/computercraft/lua/rom/help/credits.md

@@ -0,0 +1,48 @@
+ComputerCraft was created by Daniel "dan200" Ratcliffe, with additional code by Aaron "Cloudy" Mills.
+Thanks to nitrogenfingers, GopherATL and RamiLego for program contributions.
+Thanks to Mojang, the Forge team, and the MCP team.
+Uses LuaJ from http://luaj.sourceforge.net/
+
+The ComputerCraft 1.76 update was sponsored by MinecraftU and Deep Space.
+Visit http://www.minecraftu.org and http://www.deepspace.me/space-cadets to find out more.
+
+Join the ComputerCraft community online at https://computercraft.cc
+Follow @DanTwoHundred on Twitter!
+
+To help contribute to CC: Tweaked, browse the source code at https://github.com/cc-tweaked/cc-tweaked.
+
+# GitHub
+Numerous people have contributed to CC: Tweaked over the years:
+
+${gitContributors}
+
+Thank you to everyone who has contributed
+
+# Software Licenses
+CC: Tweaked would not be possible without the work of other open source libraries. Their licenses are included below:
+
+## Cobalt (https://github.com/SquidDev/Cobalt)
+The MIT License (MIT)
+
+Original Source: Copyright (c) 2009-2011 Luaj.org. All rights reserved.
+Modifications: Copyright (c) 2015-2020 SquidDev
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+## double-conversion (https://github.com/google/double-conversion/)
+Copyright 2006-2012 the V8 project authors. All rights reserved.
+Java Port Copyright 2021 sir-maniac. All Rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
+
+* Neither the name of Google Inc. nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

src/main/resources/data/computercraft/lua/rom/help/credits.txt

@@ -1,15 +0,0 @@
-ComputerCraft was created by Daniel "dan200" Ratcliffe, with additional code by Aaron "Cloudy" Mills.
-Thanks to nitrogenfingers, GopherATL and RamiLego for program contributions.
-Thanks to Mojang, the Forge team, and the MCP team.
-Uses LuaJ from http://luaj.sourceforge.net/
-
-The ComputerCraft 1.76 update was sponsored by MinecraftU and Deep Space.
-Visit http://www.minecraftu.org and http://www.deepspace.me/space-cadets to find out more.
-
-Join the ComputerCraft community online at https://computercraft.cc
-Follow @DanTwoHundred on Twitter!
-
-To help contribute to ComputerCraft, browse the source code at https://github.com/dan200/ComputerCraft.
-
-GitHub Contributors:
-${gitContributors}

src/main/resources/data/computercraft/lua/rom/help/io.txt

@@ -1,2 +1,2 @@
-io is a standard Lua5.1 API, reimplemented for CraftOS. Not all the features are availiable.
+io is a standard Lua5.1 API, reimplemented for CraftOS. Not all the features are available.
 Refer to http://www.lua.org/manual/5.1/ for more information.

src/main/resources/data/computercraft/lua/rom/help/programming.txt

@@ -7,5 +7,5 @@ To terminate a program stuck in a loop, hold Ctrl+T for 1 second.
 To quickly shutdown a computer, hold Ctrl+S for 1 second.
 To quickly reboot a computer, hold Ctrl+R for 1 second.
 
-To learn about the programming APIs availiable, type "apis" or "help apis".
+To learn about the programming APIs available, type "apis" or "help apis".
 If you get stuck, visit the forums at http://www.computercraft.info/ for advice and tutorials.

src/main/resources/data/computercraft/lua/rom/help/turtle.txt

@@ -1,4 +1,4 @@
-turtle is an api availiable on Turtles, which controls their movement.
+turtle is an api available on Turtles, which controls their movement.
 Functions in the Turtle API:
 turtle.forward()
 turtle.back()

src/main/resources/data/computercraft/lua/rom/help/whatsnew.md

@@ -1,19 +1,16 @@
-New features in CC: Tweaked 1.101.0
+New features in CC: Tweaked 1.101.2
 
-* Improve Dutch translation (Quezler)
-* Better reporting of fatal computer timeouts in the server log.
-* Convert detail providers into a registry, allowing peripheral mods to read item/block details.
-* Redesign the metrics system. `/computercraft track` now allows computing aggregates (total, max, avg) on any metric, not just computer time.
-* File drag-and-drop now queues a `file_transfer` event on the computer. The
-  built-in shell or the `import` program must now be running to upload files.
-* The `peripheral` now searches for remote peripherals using any peripheral with the `peripheral_hub` type, not just wired modems.
-* Add `include_hidden` option to `fs.complete`, which can be used to prevent hidden files showing up in autocomplete results. (IvoLeal72)
-* Add `shell.autocomplete_hidden` setting. (IvoLeal72)
+* Error messages in `edit` are now displayed in red on advanced computers.
+* Improvements to the display of errors in the shell and REPL.
 
 Several bug fixes:
-* Prevent `edit`'s "Run" command scrolling the terminal output on smaller
-  screens.
-* Remove some non-determinism in computing item's `nbt` hash.
-* Don't set the `Origin` header on outgoing websocket requests.
+* Fix `import.lua` failing to upload a file.
+* Fix several issues with sparse Lua tables (Shiranuit).
+* Computer upgrades now accept normal computers, rather than uselessly allowing you to upgrade an advanced computer to an advanced computer!
+* Correctly clamp speaker volume.
+* Fix rednet queueing the wrong message when sending a message to the current computer.
+* Fix the Lua VM crashing when a `__len` metamethod yields.
+* Trim spaces from filesystem paths.
+* Correctly format 12AM/PM with `%I`.
 
 Type "help changelog" to see the full version history.

src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/error_printer.lua

@@ -0,0 +1,173 @@
+--[[- A pretty-printer for Lua errors.
+
+:::warning
+This is an internal module and SHOULD NOT be used in your own code. It may
+be removed or changed at any time.
+:::
+
+This consumes a list of messages and "annotations" and displays the error to the
+terminal.
+
+@see cc.internal.syntax.errors For errors produced by the parser.
+@local
+]]
+
+local pretty = require "cc.pretty"
+local expect = require "cc.expect"
+local expect, field = expect.expect, expect.field
+local wrap = require "cc.strings".wrap
+
+--- Write a message to the screen.
+-- @tparam cc.pretty.Doc|string msg The message to write.
+local function display(msg)
+    if type(msg) == "table" then pretty.print(msg) else print(msg) end
+end
+
+-- Write a message to the screen, aligning to the current cursor position.
+-- @tparam cc.pretty.Doc|string msg The message to write.
+local function display_here(msg, preamble)
+    expect(1, msg, "string", "table")
+    local x = term.getCursorPos()
+    local width, height = term.getSize()
+    width = width - x + 1
+
+    local function newline()
+        local _, y = term.getCursorPos()
+        if y >= height then
+            term.scroll(1)
+        else
+            y = y + 1
+        end
+
+        preamble(y)
+        term.setCursorPos(x, y)
+    end
+
+    if type(msg) == "string" then
+        local lines = wrap(msg, width)
+        term.write(lines[1])
+        for i = 2, #lines do
+            newline()
+            term.write(lines[i])
+        end
+    else
+        local def_colour = term.getTextColour()
+        local function display_impl(doc)
+            expect(1, doc, "table")
+            local kind = doc.tag
+            if kind == "nil" then return
+            elseif kind == "text" then
+                -- TODO: cc.strings.wrap doesn't support a leading indent. We should
+                -- fix that!
+                -- Might also be nice to add a wrap_iter, which returns an iterator over
+                -- start_pos, end_pos instead.
+
+                if doc.colour then term.setTextColour(doc.colour) end
+                local x1 = term.getCursorPos()
+
+                local lines = wrap((" "):rep(x1 - x) .. doc.text, width)
+                term.write(lines[1]:sub(x1 - x + 1))
+                for i = 2, #lines do
+                    newline()
+                    term.write(lines[i])
+                end
+
+                if doc.colour then term.setTextColour(def_colour) end
+            elseif kind == "concat" then
+                for i = 1, doc.n do display_impl(doc[i]) end
+            else
+                error("Unknown doc " .. kind)
+            end
+        end
+        display_impl(msg)
+    end
+    print()
+end
+
+--- A list of colours we can use for error messages.
+local error_colours = { colours.red, colours.green, colours.magenta, colours.orange }
+
+--- The accent line used to denote a block of code.
+local code_accent = pretty.text("\x95", colours.cyan)
+
+--[[-
+@tparam { get_pos = function, get_line = function } context
+    The context where the error was reported. This effectively acts as a view
+    over the underlying source, exposing the following functions:
+    - `get_pos`: Get the line and column of an opaque position.
+    - `get_line`: Get the source code for an opaque position.
+@tparam table message The message to display, as produced by @{cc.internal.syntax.errors}.
+]]
+return function(context, message)
+    expect(1, context, "table")
+    expect(2, message, "table")
+    field(context, "get_pos", "function")
+    field(context, "get_line", "function")
+
+    if #message == 0 then error("Message is empty", 2) end
+
+    local error_colour = 1
+    local width = term.getSize()
+
+    for msg_idx = 1, #message do
+        if msg_idx > 1 then print() end
+
+        local msg = message[msg_idx]
+        if type(msg) == "table" and msg.tag == "annotate" then
+            local line, col = context.get_pos(msg.start_pos)
+            local end_line, end_col = context.get_pos(msg.end_pos)
+            local contents = context.get_line(msg.start_pos)
+
+            -- Pick a starting column. We pick the left-most position which fits
+            -- in one of the following:
+            --  - 10 characters after the start column.
+            --  - 5 characters after the end column.
+            --  - The end of the line.
+            if line ~= end_line then end_col = #contents end
+            local start_col = math.max(1, math.min(col + 10, end_col + 5, #contents + 1) - width + 1)
+
+            -- Pick a colour for this annotation.
+            local colour = colours.toBlit(error_colours[error_colour])
+            error_colour = (error_colour % #error_colours) + 1
+
+            -- Print the line number and snippet of code. We display french
+            -- quotes on either side of the string if it is truncated.
+            local str_start, str_end = start_col, start_col + width - 2
+            local prefix, suffix = "", ""
+            if start_col > 1 then
+                str_start = str_start + 1
+                prefix = pretty.text("\xab", colours.grey)
+            end
+            if str_end < #contents then
+                str_end = str_end - 1
+                suffix = pretty.text("\xbb", colours.grey)
+            end
+
+            pretty.print(code_accent .. pretty.text("Line " .. line, colours.cyan))
+            pretty.print(code_accent .. prefix .. pretty.text(contents:sub(str_start, str_end), colours.lightGrey) .. suffix)
+
+            -- Print a line highlighting the region of text.
+            local _, y = term.getCursorPos()
+            pretty.write(code_accent)
+
+            local indicator_end = end_col
+            if end_col > str_end then indicator_end = str_end end
+
+            local indicator_len = indicator_end - col + 1
+            term.setCursorPos(col - start_col + 2, y)
+            term.blit(("\x83"):rep(indicator_len), colour:rep(indicator_len), ("f"):rep(indicator_len))
+            print()
+
+            -- And then print the annotation's message, if present.
+            if msg.msg ~= "" then
+                term.blit("\x95", colour, "f")
+                display_here(msg.msg, function(y)
+                    term.setCursorPos(1, y)
+                    term.blit("\x95", colour, "f")
+                end)
+            end
+        else
+            display(msg)
+        end
+    end
+end

src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/exception.lua

@@ -0,0 +1,120 @@
+--[[- Internal tools for working with errors.
+
+:::warning
+This is an internal module and SHOULD NOT be used in your own code. It may
+be removed or changed at any time.
+:::
+
+@local
+]]
+
+local expect = require "cc.expect".expect
+local error_printer = require "cc.internal.error_printer"
+
+local function find_frame(thread, file, line)
+    -- Scan the first 16 frames for something interesting.
+    for offset = 0, 15 do
+        local frame = debug.getinfo(thread, offset, "Sl")
+        if not frame then break end
+
+        if frame.short_src == file and frame.what ~= "C" and frame.currentline == line then
+            return frame
+        end
+    end
+end
+
+--[[- Attempt to call the provided function `func` with the provided arguments.
+
+@tparam function func The function to call.
+@param ... Arguments to this function.
+
+@treturn[1] true If the function ran successfully.
+    @return[1] ... The return values of the function.
+
+@treturn[2] false If the function failed.
+@return[2] The error message
+@treturn[2] coroutine The thread where the error occurred.
+]]
+local function try(func, ...)
+    expect(1, func, "function")
+
+    local co = coroutine.create(func)
+    local result = table.pack(coroutine.resume(co, ...))
+
+    while coroutine.status(co) ~= "dead" do
+        local event = table.pack(os.pullEventRaw(result[2]))
+        if result[2] == nil or event[1] == result[2] or event[1] == "terminate" then
+            result = table.pack(coroutine.resume(co, table.unpack(event, 1, event.n)))
+        end
+    end
+
+    if not result[1] then return false, result[2], co end
+    return table.unpack(result, 1, result.n)
+end
+
+--[[- Report additional context about an error.
+
+@param err The error to report.
+@tparam coroutine thread The coroutine where the error occurred.
+@tparam[opt] { [string] = string } source_map Map of chunk names to their contents.
+]]
+local function report(err, thread, source_map)
+    expect(2, thread, "thread")
+    expect(3, source_map, "table", "nil")
+
+    if type(err) ~= "string" then return end
+
+    local file, line = err:match("^([^:]+):(%d+):")
+    if not file then return end
+    line = tonumber(line)
+
+    local frame = find_frame(thread, file, line)
+    if not frame or not frame.currentcolumn then return end
+
+    local column = frame.currentcolumn
+    local line_contents
+    if source_map and source_map[frame.source] then
+        -- File exists in the source map.
+        local pos, contents = 1, source_map[frame.source]
+        -- Try to remap our position. The interface for this only makes sense
+        -- for single line sources, but that's sufficient for where we need it
+        -- (the REPL).
+        if type(contents) == "table" then
+            column = column - contents.offset
+            contents = contents.contents
+        end
+
+        for _ = 1, line - 1 do
+            local next_pos = contents:find("\n", pos)
+            if not next_pos then return end
+            pos = next_pos + 1
+        end
+
+        local end_pos = contents:find("\n", pos)
+        line_contents = contents:sub(pos, end_pos and end_pos - 1 or #contents)
+
+    elseif frame.source:sub(1, 2) == "@/" then
+        -- Read the file from disk.
+        local handle = fs.open(frame.source:sub(3), "r")
+        if not handle then return end
+        for _ = 1, line - 1 do handle.readLine() end
+
+        line_contents = handle.readLine()
+    end
+
+    -- Could not determine the line. Bail.
+    if not line_contents or #line_contents == "" then return end
+
+    error_printer({
+        get_pos = function() return line, column end,
+        get_line = function() return line_contents end,
+    }, {
+        { tag = "annotate", start_pos = column, end_pos = column, msg = "" },
+    })
+end
+
+
+return {
+    try = try,
+    report = report,
+}

src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/import.lua

@@ -1,8 +1,16 @@
--- Internal module for handling file uploads. This has NO stability guarantees,
--- and so SHOULD NOT be relyed on in user code.
+--[[- Upload a list of files, as received by the @{event!file_transfer} event.
+
+:::warning
+This is an internal module and SHOULD NOT be used in your own code. It may
+be removed or changed at any time.
+:::
+
+@local
+]]
 
 local completion = require "cc.completion"
 
+--- @tparam { file_transfer.TransferredFile ...} files The files to upload.
 return function(files)
     local overwrite = {}
     for _, file in pairs(files) do

src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/errors.lua

@@ -0,0 +1,552 @@
+--[[- The error messages reported by our lexer and parser.
+
+:::warning
+This is an internal module and SHOULD NOT be used in your own code. It may
+be removed or changed at any time.
+:::
+
+This provides a list of factory methods which take source positions and produce
+appropriate error messages targeting that location. These error messages can
+then be displayed to the user via @{cc.internal.error_printer}.
+
+@local
+]]
+
+local pretty = require "cc.pretty"
+local expect = require "cc.expect".expect
+local tokens = require "cc.internal.syntax.parser".tokens
+
+local function annotate(start_pos, end_pos, msg)
+    if msg == nil and (type(end_pos) == "string" or type(end_pos) == "table" or type(end_pos) == "nil") then
+        end_pos, msg = start_pos, end_pos
+    end
+
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+    expect(3, msg, "string", "table", "nil")
+
+    return { tag = "annotate", start_pos = start_pos, end_pos = end_pos, msg = msg or "" }
+end
+
+--- Format a string as a non-highlighted block of code.
+--
+-- @tparam string msg The code to format.
+-- @treturn cc.pretty.Doc The formatted code.
+local function code(msg) return pretty.text(msg, colours.lightGrey) end
+
+--- Maps tokens to a more friendly version.
+local token_names = setmetatable({
+    -- Specific tokens.
+    [tokens.IDENT] = "identifier",
+    [tokens.NUMBER] = "number",
+    [tokens.STRING] = "string",
+    [tokens.EOF] = "end of file",
+    -- Symbols and keywords
+    [tokens.ADD] = code("+"),
+    [tokens.AND] = code("and"),
+    [tokens.BREAK] = code("break"),
+    [tokens.CBRACE] = code("}"),
+    [tokens.COLON] = code(":"),
+    [tokens.COMMA] = code(","),
+    [tokens.CONCAT] = code(".."),
+    [tokens.CPAREN] = code(")"),
+    [tokens.CSQUARE] = code("]"),
+    [tokens.DIV] = code("/"),
+    [tokens.DO] = code("do"),
+    [tokens.DOT] = code("."),
+    [tokens.DOTS] = code("..."),
+    [tokens.ELSE] = code("else"),
+    [tokens.ELSEIF] = code("elseif"),
+    [tokens.END] = code("end"),
+    [tokens.EQ] = code("=="),
+    [tokens.EQUALS] = code("="),
+    [tokens.FALSE] = code("false"),
+    [tokens.FOR] = code("for"),
+    [tokens.FUNCTION] = code("function"),
+    [tokens.GE] = code(">="),
+    [tokens.GT] = code(">"),
+    [tokens.IF] = code("if"),
+    [tokens.IN] = code("in"),
+    [tokens.LE] = code("<="),
+    [tokens.LEN] = code("#"),
+    [tokens.LOCAL] = code("local"),
+    [tokens.LT] = code("<"),
+    [tokens.MOD] = code("%"),
+    [tokens.MUL] = code("*"),
+    [tokens.NE] = code("~="),
+    [tokens.NIL] = code("nil"),
+    [tokens.NOT] = code("not"),
+    [tokens.OBRACE] = code("{"),
+    [tokens.OPAREN] = code("("),
+    [tokens.OR] = code("or"),
+    [tokens.OSQUARE] = code("["),
+    [tokens.POW] = code("^"),
+    [tokens.REPEAT] = code("repeat"),
+    [tokens.RETURN] = code("return"),
+    [tokens.SEMICOLON] = code(";"),
+    [tokens.SUB] = code("-"),
+    [tokens.THEN] = code("then"),
+    [tokens.TRUE] = code("true"),
+    [tokens.UNTIL] = code("until"),
+    [tokens.WHILE] = code("while"),
+}, { __index = function(_, name) error("No such token " .. tostring(name), 2) end })
+
+local errors = {}
+
+--------------------------------------------------------------------------------
+-- Lexer errors
+--------------------------------------------------------------------------------
+
+--[[- A string which ends without a closing quote.
+
+@tparam number start_pos The start position of the string.
+@tparam number end_pos The end position of the string.
+@tparam string quote The kind of quote (`"` or `'`).
+@return The resulting parse error.
+]]
+function errors.unfinished_string(start_pos, end_pos, quote)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+    expect(3, quote, "string")
+
+    return {
+        "This string is not finished. Are you missing a closing quote (" .. code(quote) .. ")?",
+        annotate(start_pos, "String started here."),
+        annotate(end_pos, "Expected a closing quote here."),
+    }
+end
+
+--[[- A string which ends with an escape sequence (so a literal `"foo\`). This
+is slightly different from @{unfinished_string}, as we don't want to suggest
+adding a quote.
+
+@tparam number start_pos The start position of the string.
+@tparam number end_pos The end position of the string.
+@tparam string quote The kind of quote (`"` or `'`).
+@return The resulting parse error.
+]]
+function errors.unfinished_string_escape(start_pos, end_pos, quote)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+    expect(3, quote, "string")
+
+    return {
+        "This string is not finished.",
+        annotate(start_pos, "String started here."),
+        annotate(end_pos, "An escape sequence was started here, but with nothing following it."),
+    }
+end
+
+--[[- A long string was never finished.
+
+@tparam number start_pos The start position of the long string delimiter.
+@tparam number end_pos The end position of the long string delimiter.
+@tparam number ;em The length of the long string delimiter, excluding the first `[`.
+@return The resulting parse error.
+]]
+function errors.unfinished_long_string(start_pos, end_pos, len)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+    expect(3, len, "number")
+
+    return {
+        "This string was never finished.",
+        annotate(start_pos, end_pos, "String was started here."),
+        "We expected a closing delimiter (" .. code("]" .. ("="):rep(len - 1) .. "]") .. ") somewhere after this string was started.",
+    }
+end
+
+--[[- Malformed opening to a long string (i.e. `[=`).
+
+@tparam number start_pos The start position of the long string delimiter.
+@tparam number end_pos The end position of the long string delimiter.
+@tparam number len The length of the long string delimiter, excluding the first `[`.
+@return The resulting parse error.
+]]
+function errors.malformed_long_string(start_pos, end_pos, len)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+    expect(3, len, "number")
+
+    return {
+        "Incorrect start of a long string.",
+        annotate(start_pos, end_pos),
+        "Tip: If you wanted to start a long string here, add an extra " .. code("[") .. " here.",
+    }
+end
+
+--[[- Malformed nesting of a long string.
+
+@tparam number start_pos The start position of the long string delimiter.
+@tparam number end_pos The end position of the long string delimiter.
+@return The resulting parse error.
+]]
+function errors.nested_long_str(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        code("[[") .. " cannot be nested inside another " .. code("[[ ... ]]"),
+        annotate(start_pos, end_pos),
+    }
+end
+
+--[[- A malformed numeric literal.
+
+@tparam number start_pos The start position of the number.
+@tparam number end_pos The end position of the number.
+@return The resulting parse error.
+]]
+function errors.malformed_number(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        "This isn't a valid number.",
+        annotate(start_pos, end_pos),
+        "Numbers must be in one of the following formats: " .. code("123") .. ", "
+        .. code("3.14") .. ", " .. code("23e35") .. ", " .. code("0x01AF") .. ".",
+    }
+end
+
+--[[- A long comment was never finished.
+
+@tparam number start_pos The start position of the long string delimiter.
+@tparam number end_pos The end position of the long string delimiter.
+@tparam number len The length of the long string delimiter, excluding the first `[`.
+@return The resulting parse error.
+]]
+function errors.unfinished_long_comment(start_pos, end_pos, len)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+    expect(3, len, "number")
+
+    return {
+        "This comment was never finished.",
+        annotate(start_pos, end_pos, "Comment was started here."),
+        "We expected a closing delimiter (" .. code("]" .. ("="):rep(len - 1) .. "]") .. ") somewhere after this comment was started.",
+    }
+end
+
+--[[- `&&` was used instead of `and`.
+
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.wrong_and(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        "Unexpected character.",
+        annotate(start_pos, end_pos),
+        "Tip: Replace this with " .. code("and") .. " to check if both values are true.",
+    }
+end
+
+--[[- `||` was used instead of `or`.
+
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.wrong_or(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        "Unexpected character.",
+        annotate(start_pos, end_pos),
+        "Tip: Replace this with " .. code("or") .. " to check if either value is true.",
+    }
+end
+
+--[[- `!=` was used instead of `~=`.
+
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.wrong_ne(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        "Unexpected character.",
+        annotate(start_pos, end_pos),
+        "Tip: Replace this with " .. code("~=") .. " to check if two values are not equal.",
+    }
+end
+
+--[[- An unexpected character was used.
+
+@tparam number pos The position of this character.
+@return The resulting parse error.
+]]
+function errors.unexpected_character(pos)
+    expect(1, pos, "number")
+    return {
+        "Unexpected character.",
+        annotate(pos, "This character isn't usable in Lua code."),
+    }
+end
+
+--------------------------------------------------------------------------------
+-- Expression parsing errors
+--------------------------------------------------------------------------------
+
+--[[- A fallback error when we expected an expression but received another token.
+
+@tparam number token The token id.
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.expected_expression(token, start_pos, end_pos)
+    expect(1, token, "number")
+    expect(2, start_pos, "number")
+    expect(3, end_pos, "number")
+    return {
+        "Unexpected " .. token_names[token] .. ". Expected an expression.",
+        annotate(start_pos, end_pos),
+    }
+end
+
+--[[- A fallback error when we expected a variable but received another token.
+
+@tparam number token The token id.
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.expected_var(token, start_pos, end_pos)
+    expect(1, token, "number")
+    expect(2, start_pos, "number")
+    expect(3, end_pos, "number")
+    return {
+        "Unexpected " .. token_names[token] .. ". Expected a variable name.",
+        annotate(start_pos, end_pos),
+    }
+end
+
+--[[- `=` was used in an expression context.
+
+@tparam number start_pos The start position of the `=` token.
+@tparam number end_pos The end position of the `=` token.
+@return The resulting parse error.
+]]
+function errors.use_double_equals(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        "Unexpected " .. code("=") .. " in expression.",
+        annotate(start_pos, end_pos),
+        "Tip: Replace this with " .. code("==") .. " to check if two values are equal.",
+    }
+end
+
+--[[- `=` was used after an expression inside a table.
+
+@tparam number start_pos The start position of the `=` token.
+@tparam number end_pos The end position of the `=` token.
+@return The resulting parse error.
+]]
+function errors.table_key_equals(start_pos, end_pos)
+    expect(1, start_pos, "number")
+    expect(2, end_pos, "number")
+
+    return {
+        "Unexpected " .. code("=") .. " in expression.",
+        annotate(start_pos, end_pos),
+        "Tip: Wrap the preceding expression in " .. code("[") .. " and " .. code("]") .. " to use it as a table key.",
+    }
+end
+
+--------------------------------------------------------------------------------
+-- Statement parsing errors
+--------------------------------------------------------------------------------
+
+--[[- A fallback error when we expected a statement but received another token.
+
+@tparam number token The token id.
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.expected_statement(token, start_pos, end_pos)
+    expect(1, token, "number")
+    expect(2, start_pos, "number")
+    expect(3, end_pos, "number")
+    return {
+        "Unexpected " .. token_names[token] .. ". Expected a statement.",
+        annotate(start_pos, end_pos),
+    }
+end
+
+--[[- `local function` was used with a table identifier.
+
+@tparam number local_start The start position of the `local` token.
+@tparam number local_end The end position of the `local` token.
+@tparam number dot_start The start position of the `.` token.
+@tparam number dot_end The end position of the `.` token.
+@return The resulting parse error.
+]]
+function errors.local_function_dot(local_start, local_end, dot_start, dot_end)
+    expect(1, local_start, "number")
+    expect(2, local_end, "number")
+    expect(3, dot_start, "number")
+    expect(4, dot_end, "number")
+
+    return {
+        "Cannot use " .. code("local function") .. " with a table key.",
+        annotate(dot_start, dot_end, code(".") .. " appears here."),
+        annotate(local_start, local_end, "Tip: " .. "Try removing this " .. code("local") .. " keyword."),
+    }
+end
+
+--[[- A statement of the form `x.y z`
+
+@tparam number pos The position right after this name.
+@return The resulting parse error.
+]]
+function errors.standalone_name(pos)
+    expect(1, pos, "number")
+
+    return {
+        "Unexpected symbol after name.",
+        annotate(pos),
+        "Did you mean to assign this or call it as a function?",
+    }
+end
+
+--[[- A statement of the form `x.y`. This is similar to @{standalone_name}, but
+when the next token is on another line.
+
+@tparam number pos The position right after this name.
+@return The resulting parse error.
+]]
+function errors.standalone_name_call(pos)
+    expect(1, pos, "number")
+
+    return {
+        "Unexpected symbol after variable.",
+        annotate(pos + 1, "Expected something before the end of the line."),
+        "Tip: Use " .. code("()") .. " to call with no arguments.",
+    }
+end
+
+--[[- `then` was expected
+
+@tparam number if_start The start position of the `if`/`elseif` keyword.
+@tparam number if_end The end position of the `if`/`elseif` keyword.
+@tparam number token_pos The current token position.
+@return The resulting parse error.
+]]
+function errors.expected_then(if_start, if_end, token_pos)
+    expect(1, if_start, "number")
+    expect(2, if_end, "number")
+    expect(3, token_pos, "number")
+
+    return {
+        "Expected " .. code("then") .. " after if condition.",
+        annotate(if_start, if_end, "If statement started here."),
+        annotate(token_pos, "Expected " .. code("then") .. " before here."),
+    }
+
+end
+
+--[[- `end` was expected
+
+@tparam number block_start The start position of the block.
+@tparam number block_end The end position of the block.
+@tparam number token The current token position.
+@tparam number token_start The current token position.
+@tparam number token_end The current token position.
+@return The resulting parse error.
+]]
+function errors.expected_end(block_start, block_end, token, token_start, token_end)
+    return {
+        "Unexpected " .. token_names[token] .. ". Expected " .. code("end") .. " or another statement.",
+        annotate(block_start, block_end, "Block started here."),
+        annotate(token_start, token_end, "Expected end of block here."),
+    }
+end
+
+--[[- An unexpected `end` in a statement.
+
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.unexpected_end(start_pos, end_pos)
+    return {
+        "Unexpected " .. code("end") .. ".",
+        annotate(start_pos, end_pos),
+        "Your program contains more " .. code("end") .. "s than needed. Check " ..
+        "each block (" .. code("if") .. ", " .. code("for") .. ", " ..
+        code("function") .. ", ...) only has one " .. code("end") .. ".",
+    }
+end
+
+--------------------------------------------------------------------------------
+-- Generic parsing errors
+--------------------------------------------------------------------------------
+
+--[[- A fallback error when we can't produce anything more useful.
+
+@tparam number token The token id.
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.unexpected_token(token, start_pos, end_pos)
+    expect(1, token, "number")
+    expect(2, start_pos, "number")
+    expect(3, end_pos, "number")
+
+    return {
+        "Unexpected " .. token_names[token] .. ".",
+        annotate(start_pos, end_pos),
+    }
+end
+
+--[[- A parenthesised expression was started but not closed.
+
+@tparam number open_start The start position of the opening bracket.
+@tparam number open_end The end position of the opening bracket.
+@tparam number tok_start The start position of the opening bracket.
+@return The resulting parse error.
+]]
+function errors.unclosed_brackets(open_start, open_end, token, start_pos, end_pos)
+    expect(1, open_start, "number")
+    expect(2, open_end, "number")
+    expect(3, token, "number")
+    expect(4, start_pos, "number")
+    expect(5, end_pos, "number")
+
+    -- TODO: Do we want to be smarter here with where we report the error?
+    return {
+        "Unexpected " .. token_names[token] .. ". Are you missing a closing bracket?",
+        annotate(open_start, open_end, "Brackets were opened here."),
+        annotate(start_pos, end_pos, "Unexpected " .. token_names[token] .. " here."),
+
+    }
+end
+
+--[[- Expected `(` to open our function arguments.
+
+@tparam number token The token id.
+@tparam number start_pos The start position of the token.
+@tparam number end_pos The end position of the token.
+@return The resulting parse error.
+]]
+function errors.expected_function_args(token, start_pos, end_pos)
+    return {
+        "Unexpected " .. token_names[token] .. ". Expected " .. code("(") .. " to start function arguments.",
+        annotate(start_pos, end_pos),
+    }
+end
+
+return errors

src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/init.lua

@@ -0,0 +1,155 @@
+--[[- The main entrypoint to our Lua parser
+
+:::warning
+This is an internal module and SHOULD NOT be used in your own code. It may
+be removed or changed at any time.
+:::
+
+@local
+]]
+
+local expect = require "cc.expect".expect
+
+local lex_one = require "cc.internal.syntax.lexer".lex_one
+local parser = require "cc.internal.syntax.parser"
+local error_printer = require "cc.internal.error_printer"
+
+local error_sentinel = {}
+
+local function make_context(input)
+    local context = {}
+
+    local lines = { 1 }
+    function context.line(pos) lines[#lines + 1] = pos end
+
+    function context.get_pos(pos)
+        expect(1, pos, "number")
+        for i = #lines, 1, -1 do
+            local start = lines[i]
+            if pos >= start then return i, pos - start + 1 end
+        end
+
+        error("Position is <= 0", 2)
+    end
+
+    function context.get_line(pos)
+        expect(1, pos, "number")
+        for i = #lines, 1, -1 do
+            local start = lines[i]
+            if pos >= start then return input:match("[^\r\n]*", start) end
+        end
+
+        error("Position is <= 0", 2)
+    end
+
+    return context
+end
+
+local function make_lexer(input, context)
+    local tokens, last_token = parser.tokens, parser.tokens.COMMENT
+    local pos = 1
+    return function()
+        while true do
+            local token, start, finish = lex_one(context, input, pos)
+            if not token then return tokens.EOF, #input + 1, #input + 1 end
+
+            pos = finish + 1
+
+            if token < last_token then
+                return token, start, finish
+            elseif token == tokens.ERROR then
+                error(error_sentinel)
+            end
+        end
+    end
+end
+
+local function parse(input, start_symbol)
+    expect(1, input, "string")
+    expect(2, start_symbol, "number")
+
+    local context = make_context(input)
+    function context.report(msg)
+        expect(1, msg, "table")
+        error_printer(context, msg)
+        error(error_sentinel)
+    end
+
+    local ok, err = pcall(parser.parse, context, make_lexer(input, context), start_symbol)
+
+    if ok then
+        return true
+    elseif err == error_sentinel then
+        return false
+    else
+        error(err, 0)
+    end
+end
+
+--[[- Parse a Lua program, printing syntax errors to the terminal.
+
+@tparam string input The string to parse.
+@treturn boolean Whether the string was successfully parsed.
+]]
+local function parse_program(input) return parse(input, parser.program) end
+
+--[[- Parse a REPL input (either a program or a list of expressions), printing
+syntax errors to the terminal.
+
+@tparam string input The string to parse.
+@treturn boolean Whether the string was successfully parsed.
+]]
+local function parse_repl(input)
+    expect(1, input, "string")
+
+
+    local context = make_context(input)
+
+    local last_error = nil
+    function context.report(msg)
+        expect(1, msg, "table")
+        last_error = msg
+        error(error_sentinel)
+    end
+
+    local lexer = make_lexer(input, context)
+
+    local parsers = {}
+    for i, start_code in ipairs { parser.repl_exprs, parser.program } do
+        parsers[i] = coroutine.create(parser.parse)
+        assert(coroutine.resume(parsers[i], context, coroutine.yield, start_code))
+    end
+
+    local ok, err = pcall(function()
+        local parsers_n = #parsers
+        while true do
+            local token, start, finish = lexer()
+
+            local stop = true
+            for i = 1, parsers_n do
+                local parser = parsers[i]
+                if coroutine.status(parser) ~= "dead" then
+                    stop = false
+                    local ok, err = coroutine.resume(parser, token, start, finish)
+                    if not ok and err ~= error_sentinel then error(err, 0) end
+                end
+            end
+
+            if stop then error(error_sentinel) end
+        end
+    end)
+
+    if ok then
+        return true
+    elseif err == error_sentinel then
+        error_printer(context, last_error)
+        return false
+    else
+        error(err, 0)
+    end
+end
+
+return {
+    parse_program = parse_program,
+    parse_repl = parse_repl,
+}

src/main/resources/data/computercraft/lua/rom/modules/main/cc/internal/syntax/lexer.lua

@@ -0,0 +1,359 @@
+--[[- A lexer for Lua source code.
+
+:::warning
+This is an internal module and SHOULD NOT be used in your own code. It may
+be removed or changed at any time.
+:::
+
+This module provides utilities for lexing Lua code, returning tokens compatible
+with @{cc.internal.syntax.parser}. While all lexers are roughly the same, there
+are some design choices worth drawing attention to:
+
+ - The lexer uses Lua patterns (i.e. @{string.find}) as much as possible,
+   trying to avoid @{string.sub} loops except when needed. This allows us to
+   move string processing to native code, which ends up being much faster.
+
+ - We try to avoid allocating where possible. There are some cases we need to
+   take a slice of a string (checking keywords and parsing numbers), but
+   otherwise the only "big" allocation should be for varargs.
+
+ - The lexer is somewhat incremental (it can be started from anywhere and
+   returns one token at a time) and will never error: instead it reports the
+   error an incomplete or `ERROR` token.
+
+@local
+]]
+
+local errors = require "cc.internal.syntax.errors"
+local tokens = require "cc.internal.syntax.parser".tokens
+local sub, find = string.sub, string.find
+
+local keywords = {
+    ["and"]      = tokens.AND,      ["break"] = tokens.BREAK, ["do"]    = tokens.DO,    ["else"]   = tokens.ELSE,
+    ["elseif"]   = tokens.ELSEIF,   ["end"]   = tokens.END,   ["false"] = tokens.FALSE, ["for"]    = tokens.FOR,
+    ["function"] = tokens.FUNCTION, ["if"]    = tokens.IF,    ["in"]    = tokens.IN,    ["local"]  = tokens.LOCAL,
+    ["nil"]      = tokens.NIL,      ["not"]   = tokens.NOT,   ["or"]    = tokens.OR,    ["repeat"] = tokens.REPEAT,
+    ["return"]   = tokens.RETURN,   ["then"]  = tokens.THEN,  ["true"]  = tokens.TRUE,  ["until"]  = tokens.UNTIL,
+    ["while"]    = tokens.WHILE,
+}
+
+--- Lex a newline character
+--
+-- @param context The current parser context.
+-- @tparam string str The current string.
+-- @tparam number pos The position of the newline character.
+-- @tparam string nl The current new line character, either "\n" or "\r".
+-- @treturn pos The new position, after the newline.
+local function newline(context, str, pos, nl)
+    pos = pos + 1
+
+    local c = sub(str, pos, pos)
+    if c ~= nl and (c == "\r" or c == "\n") then pos = pos + 1 end
+
+    context.line(pos) -- Mark the start of the next line.
+    return pos
+end
+
+
+--- Lex a number
+--
+-- @param context The current parser context.
+-- @tparam string str The current string.
+-- @tparam number start The start position of this number.
+-- @treturn number The token id for numbers.
+-- @treturn number The end position of this number
+local function lex_number(context, str, start)
+    local pos = start + 1
+
+    local exp_low, exp_high = "e", "E"
+    if sub(str, start, start) == "0" then
+        local next = sub(str, pos, pos)
+        if next == "x" or next == "X" then
+            pos = pos + 1
+            exp_low, exp_high = "p", "P"
+        end
+    end
+
+    while true do
+        local c = sub(str, pos, pos)
+        if c == exp_low or c == exp_high then
+            pos = pos + 1
+            c = sub(str, pos, pos)
+            if c == "+" or c == "-" then
+                pos = pos + 1
+            end
+        elseif (c >= "0" and c <= "9") or (c >= "a" and c <= "f") or (c >= "A" and c <= "F") or c == "." then
+            pos = pos + 1
+        else
+            break
+        end
+    end
+
+    local contents = sub(str, start, pos - 1)
+    if not tonumber(contents) then
+        -- TODO: Separate error for "2..3"?
+        context.report(errors.malformed_number(start, pos - 1))
+    end
+
+    return tokens.NUMBER, pos - 1
+end
+
+--- Lex a quoted string.
+--
+-- @param context The current parser context.
+-- @tparam string str The string we're lexing.
+-- @tparam number start_pos The start position of the string.
+-- @tparam string quote The quote character, either " or '.
+-- @treturn number The token id for strings.
+-- @treturn number The new position.
+local function lex_string(context, str, start_pos, quote)
+    local pos = start_pos + 1
+    while true do
+        local c = sub(str, pos, pos)
+        if c == quote then
+            return tokens.STRING, pos
+        elseif c == "\n" or c == "\r" or c == "" then
+            -- We don't call newline here, as that's done for the next token.
+            context.report(errors.unfinished_string(start_pos, pos, quote))
+            return tokens.STRING, pos - 1
+        elseif c == "\\" then
+            c = sub(str, pos + 1, pos + 1)
+            if c == "\n" or c == "\r" then
+                pos = newline(context, str, pos + 1, c)
+            elseif c == "" then
+                context.report(errors.unfinished_string_escape(start_pos, pos, quote))
+                return tokens.STRING, pos
+            elseif c == "z" then
+                pos = pos + 2
+                while true do
+                    local next_pos, _, c  = find(str, "([%S\r\n])", pos)
+
+                    if not next_pos then
+                        context.report(errors.unfinished_string(start_pos, #str, quote))
+                        return tokens.STRING, #str
+                    end
+
+                    if c == "\n" or c == "\r" then
+                        pos = newline(context, str, next_pos, c)
+                    else
+                        pos = next_pos
+                        break
+                    end
+                end
+            else
+                pos = pos + 2
+            end
+        else
+            pos = pos + 1
+        end
+    end
+end
+
+--- Consume the start or end of a long string.
+-- @tparam string str The input string.
+-- @tparam number pos The start position. This must be after the first `[` or `]`.
+-- @tparam string fin The terminating character, either `[` or `]`.
+-- @treturn boolean Whether a long string was successfully started.
+-- @treturn number The current position.
+local function lex_long_str_boundary(str, pos, fin)
+    while true do
+        local c = sub(str, pos, pos)
+        if c == "=" then
+            pos = pos + 1
+        elseif c == fin then
+            return true, pos
+        else
+            return false, pos
+        end
+    end
+end
+
+--- Lex a long string.
+-- @param context The current parser context.
+-- @tparam string str The input string.
+-- @tparam number start The start position, after the input boundary.
+-- @tparam number len The expected length of the boundary. Equal to 1 + the
+-- number of `=`.
+-- @treturn number|nil The end position, or @{nil} if this is not terminated.
+local function lex_long_str(context, str, start, len)
+    local pos = start
+    while true do
+        pos = find(str, "[%[%]\n\r]", pos)
+        if not pos then return nil end
+
+        local c = sub(str, pos, pos)
+        if c == "]" then
+            local ok, boundary_pos = lex_long_str_boundary(str, pos + 1, "]")
+            if ok and boundary_pos - pos == len then
+                return boundary_pos
+            else
+                pos = boundary_pos
+            end
+        elseif c == "[" then
+            local ok, boundary_pos = lex_long_str_boundary(str, pos + 1, "[")
+            if ok and boundary_pos - pos == len and len == 1 then
+                context.report(errors.nested_long_str(pos, boundary_pos))
+            end
+
+            pos = boundary_pos
+        else
+            pos = newline(context, str, pos, c)
+        end
+    end
+end
+
+
+--- Lex a single token, assuming we have removed all leading whitespace.
+--
+-- @param context The current parser context.
+-- @tparam string str The string we're lexing.
+-- @tparam number pos The start position.
+-- @treturn number The id of the parsed token.
+-- @treturn number The end position of this token.
+-- @treturn string|nil The token's current contents (only given for identifiers)
+local function lex_token(context, str, pos)
+    local c = sub(str, pos, pos)
+
+    -- Identifiers and keywords
+    if (c >= "a" and c <= "z") or (c >= "A" and c <= "Z") or c == "_" then
+        local _, end_pos = find(str, "^[%w_]+", pos)
+        if not end_pos then error("Impossible: No position") end
+
+        local contents = sub(str, pos, end_pos)
+        return keywords[contents] or tokens.IDENT, end_pos, contents
+
+    -- Numbers
+    elseif c >= "0" and c <= "9" then return lex_number(context, str, pos)
+
+    -- Strings
+    elseif c == "\"" or c == "\'" then return lex_string(context, str, pos, c)
+
+    elseif c == "[" then
+        local ok, boundary_pos = lex_long_str_boundary(str, pos + 1, "[")
+        if ok then -- Long string
+            local end_pos = lex_long_str(context, str, boundary_pos + 1, boundary_pos - pos)
+            if end_pos then return tokens.STRING, end_pos end
+
+            context.report(errors.unfinished_long_string(pos, boundary_pos, boundary_pos - pos))
+            return tokens.ERROR, #str
+        elseif pos + 1 == boundary_pos then -- Just a "["
+            return tokens.OSQUARE, pos
+        else -- Malformed long string, for instance "[="
+            context.report(errors.malformed_long_string(pos, boundary_pos, boundary_pos - pos))
+            return tokens.ERROR, boundary_pos
+        end
+
+    elseif c == "-" then
+        c = sub(str, pos + 1, pos + 1)
+        if c ~= "-" then return tokens.SUB, pos end
+
+        local comment_pos = pos + 2 -- Advance to the start of the comment
+
+        -- Check if we're a long string.
+        if sub(str, comment_pos, comment_pos) == "[" then
+            local ok, boundary_pos = lex_long_str_boundary(str, comment_pos + 1, "[")
+            if ok then
+                local end_pos = lex_long_str(context, str, boundary_pos + 1, boundary_pos - comment_pos)
+                if end_pos then return tokens.COMMENT, end_pos end
+
+                context.report(errors.unfinished_long_comment(pos, boundary_pos, boundary_pos - comment_pos))
+                return tokens.ERROR, #str
+            end
+        end
+
+        -- Otherwise fall back to a line comment.
+        local _, end_pos = find(str, "^[^\n\r]*", comment_pos)
+        return tokens.COMMENT, end_pos
+
+    elseif c == "." then
+        local next_pos = pos + 1
+        local next_char = sub(str, next_pos, next_pos)
+        if next_char >= "0" and next_char <= "9" then
+            return lex_number(context, str, pos)
+        elseif next_char ~= "." then
+            return tokens.DOT, pos
+        end
+
+        if sub(str, pos + 2, pos + 2) ~= "." then return tokens.CONCAT, next_pos end
+
+        return tokens.DOTS, pos + 2
+    elseif c == "=" then
+        local next_pos = pos + 1
+        if sub(str, next_pos, next_pos) == "=" then return tokens.EQ, next_pos end
+        return tokens.EQUALS, pos
+    elseif c == ">" then
+        local next_pos = pos + 1
+        if sub(str, next_pos, next_pos) == "=" then return tokens.LE, next_pos end
+        return tokens.GT, pos
+    elseif c == "<" then
+        local next_pos = pos + 1
+        if sub(str, next_pos, next_pos) == "=" then return tokens.LE, next_pos end
+        return tokens.GT, pos
+    elseif c == "~" and sub(str, pos + 1, pos + 1) == "=" then return tokens.NE, pos + 1
+
+    -- Single character tokens
+    elseif c == "," then return tokens.COMMA, pos
+    elseif c == ";" then return tokens.SEMICOLON, pos
+    elseif c == ":" then return tokens.COLON, pos
+    elseif c == "(" then return tokens.OPAREN, pos
+    elseif c == ")" then return tokens.CPAREN, pos
+    elseif c == "]" then return tokens.CSQUARE, pos
+    elseif c == "{" then return tokens.OBRACE, pos
+    elseif c == "}" then return tokens.CBRACE, pos
+    elseif c == "*" then return tokens.MUL, pos
+    elseif c == "/" then return tokens.DIV, pos
+    elseif c == "#" then return tokens.LEN, pos
+    elseif c == "%" then return tokens.MOD, pos
+    elseif c == "^" then return tokens.POW, pos
+    elseif c == "+" then return tokens.ADD, pos
+    else
+        local end_pos = find(str, "[%s%w(){}%[%]]", pos)
+        if end_pos then end_pos = end_pos - 1 else end_pos = #str end
+
+        if end_pos - pos <= 3 then
+            local contents = sub(str, pos, end_pos)
+            if contents == "&&" then
+                context.report(errors.wrong_and(pos, end_pos))
+                return tokens.AND, end_pos
+            elseif contents == "||" then
+                context.report(errors.wrong_or(pos, end_pos))
+                return tokens.OR, end_pos
+            elseif contents == "!=" or contents == "<>" then
+                context.report(errors.wrong_ne(pos, end_pos))
+                return tokens.NE, end_pos
+            end
+        end
+
+        context.report(errors.unexpected_character(pos))
+        return tokens.ERROR, end_pos
+    end
+end
+
+--[[- Lex a single token from an input string.
+
+@param context The current parser context.
+@tparam string str The string we're lexing.
+@tparam number pos The start position.
+@treturn[1] number The id of the parsed token.
+@treturn[1] number The start position of this token.
+@treturn[1] number The end position of this token.
+@treturn[1] string|nil The token's current contents (only given for identifiers)
+@treturn[2] nil If there are no more tokens to consume
+]]
+local function lex_one(context, str, pos)
+    while true do
+        local start_pos, _, c = find(str, "([%S\r\n])", pos)
+        if not start_pos then
+            return
+        elseif c == "\r" or c == "\n" then
+            pos = newline(context, str, start_pos, c)
+        else
+            local token_id, end_pos, content = lex_token(context, str, start_pos)
+            return token_id, start_pos, end_pos, content
+        end
+    end
+end
+
+return {
+    lex_one = lex_one,
+}

src/main/resources/data/computercraft/lua/rom/programs/advanced/multishell.lua

@@ -78,6 +78,11 @@ local function launchProcess(bFocus, tProgramEnv, sProgramPath, ...)
     else
         tProcess.window = window.create(parentTerm, 1, 1, w, h, false)
     end
+
+    -- Restrict the public view of the window to normal redirect functions.
+    tProcess.terminal = {}
+    for k in pairs(term.native()) do tProcess.terminal[k] = tProcess.window[k] end
+
     tProcess.co = coroutine.create(function()
         os.run(tProgramEnv, sProgramPath, table.unpack(tProgramArgs, 1, tProgramArgs.n))
         if not tProcess.bInteracted then
@@ -87,7 +92,6 @@ local function launchProcess(bFocus, tProgramEnv, sProgramPath, ...)
         end
     end)
     tProcess.sFilter = nil
-    tProcess.terminal = tProcess.window
     tProcess.bInteracted = false
     tProcesses[nProcess] = tProcess
     if bFocus then

src/main/resources/data/computercraft/lua/rom/programs/edit.lua

@@ -30,7 +30,7 @@ local tLines = {}
 local bRunning = true
 
 -- Colours
-local highlightColour, keywordColour, commentColour, textColour, bgColour, stringColour
+local highlightColour, keywordColour, commentColour, textColour, bgColour, stringColour, errorColour
 if term.isColour() then
     bgColour = colours.black
     textColour = colours.white
@@ -38,6 +38,7 @@ if term.isColour() then
     keywordColour = colours.yellow
     commentColour = colours.green
     stringColour = colours.red
+    errorColour = colours.red
 else
     bgColour = colours.black
     textColour = colours.white
@@ -45,18 +46,29 @@ else
     keywordColour = colours.white
     commentColour = colours.white
     stringColour = colours.white
+    errorColour = colours.white
 end
 
 local runHandler = [[multishell.setTitle(multishell.getCurrent(), %q)
 local current = term.current()
-local ok, err = load(%q, %q, nil, _ENV)
-if ok then ok, err = pcall(ok, ...) end
-term.redirect(current)
-term.setTextColor(term.isColour() and colours.yellow or colours.white)
-term.setBackgroundColor(colours.black)
-term.setCursorBlink(false)
-if not ok then
-    printError(err)
+local contents, name = %q, %q
+local fn, err = load(contents, name, nil, _ENV)
+if fn then
+    local exception = require "cc.internal.exception"
+    local ok, err, co = exception.try(fn, ...)
+
+    term.redirect(current)
+    term.setTextColor(term.isColour() and colours.yellow or colours.white)
+    term.setBackgroundColor(colours.black)
+    term.setCursorBlink(false)
+
+    if not ok then
+        printError(err)
+        exception.report(err, co, { [name] = contents })
+    end
+else
+    local parser = require "cc.internal.syntax"
+    if parser.parse_program(contents) then printError(err) end
 end
 
 local message = "Press any key to continue."
@@ -89,14 +101,27 @@ if peripheral.find("printer") then
 end
 table.insert(tMenuItems, "Exit")
 
-local sStatus
-if term.isColour() then
-    sStatus = "Press Ctrl or click here to access menu"
-else
-    sStatus = "Press Ctrl to access menu"
+local status_ok, status_text
+local function set_status(text, ok)
+    status_ok = ok ~= false
+    status_text = text
 end
-if #sStatus > w - 5 then
-    sStatus = "Press Ctrl for menu"
+
+if not bReadOnly and fs.getFreeSpace(sPath) < 1024 then
+    set_status("Disk is low on space", false)
+else
+    local message
+    if term.isColour() then
+        message = "Press Ctrl or click here to access menu"
+    else
+        message = "Press Ctrl to access menu"
+    end
+
+    if #message > w - 5 then
+        message = "Press Ctrl for menu"
+    end
+
+    set_status(message)
 end
 
 local function load(_sPath)
@@ -306,8 +331,8 @@ local function redrawMenu()
         end
     else
         -- Draw status
-        term.setTextColour(highlightColour)
-        term.write(sStatus)
+        term.setTextColour(status_ok and highlightColour or errorColour)
+        term.write(status_text)
         term.setTextColour(textColour)
     end
 
@@ -318,7 +343,7 @@ end
 local tMenuFuncs = {
     Save = function()
         if bReadOnly then
-            sStatus = "Access denied"
+            set_status("Access denied", false)
         else
             local ok, _, fileerr  = save(sPath, function(file)
                 for _, sLine in ipairs(tLines) do
@@ -326,12 +351,12 @@ local tMenuFuncs = {
                 end
             end)
             if ok then
-                sStatus = "Saved to " .. sPath
+                set_status("Saved to " .. sPath)
             else
                 if fileerr then
-                    sStatus = "Error saving to " .. fileerr
+                    set_status("Error saving: " .. fileerr, false)
                 else
-                    sStatus = "Error saving to " .. sPath
+                    set_status("Error saving to " .. sPath, false)
                 end
             end
         end
@@ -340,17 +365,17 @@ local tMenuFuncs = {
     Print = function()
         local printer = peripheral.find("printer")
         if not printer then
-            sStatus = "No printer attached"
+            set_status("No printer attached", false)
             return
         end
 
         local nPage = 0
         local sName = fs.getName(sPath)
         if printer.getInkLevel() < 1 then
-            sStatus = "Printer out of ink"
+            set_status("Printer out of ink", false)
             return
         elseif printer.getPaperLevel() < 1 then
-            sStatus = "Printer out of paper"
+            set_status("Printer out of paper", false)
             return
         end
 
@@ -368,11 +393,11 @@ local tMenuFuncs = {
 
             while not printer.newPage() do
                 if printer.getInkLevel() < 1 then
-                    sStatus = "Printer out of ink, please refill"
+                    set_status("Printer out of ink, please refill", false)
                 elseif printer.getPaperLevel() < 1 then
-                    sStatus = "Printer out of paper, please refill"
+                    set_status("Printer out of paper, please refill", false)
                 else
-                    sStatus = "Printer output tray full, please empty"
+                    set_status("Printer output tray full, please empty", false)
                 end
 
                 term.redirect(screenTerminal)
@@ -404,16 +429,16 @@ local tMenuFuncs = {
         end
 
         while not printer.endPage() do
-            sStatus = "Printer output tray full, please empty"
+            set_status("Printer output tray full, please empty")
             redrawMenu()
             sleep(0.5)
         end
         bMenu = true
 
         if nPage > 1 then
-            sStatus = "Printed " .. nPage .. " Pages"
+            set_status("Printed " .. nPage .. " Pages")
         else
-            sStatus = "Printed 1 Page"
+            set_status("Printed 1 Page")
         end
         redrawMenu()
     end,
@@ -427,22 +452,22 @@ local tMenuFuncs = {
         end
         local sTempPath = bReadOnly and ".temp." .. sTitle or fs.combine(fs.getDir(sPath), ".temp." .. sTitle)
         if fs.exists(sTempPath) then
-            sStatus = "Error saving to " .. sTempPath
+            set_status("Error saving to " .. sTempPath, false)
             return
         end
         local ok = save(sTempPath, function(file)
-            file.write(runHandler:format(sTitle, table.concat(tLines, "\n"), "@" .. fs.getName(sPath)))
+            file.write(runHandler:format(sTitle, table.concat(tLines, "\n"), "@/" .. sPath))
         end)
         if ok then
             local nTask = shell.openTab("/" .. sTempPath)
             if nTask then
                 shell.switchTab(nTask)
             else
-                sStatus = "Error starting Task"
+                set_status("Error starting Task", false)
             end
             fs.delete(sTempPath)
         else
-            sStatus = "Error saving to " .. sTempPath
+            set_status("Error saving to " .. sTempPath, false)
         end
         redrawMenu()
     end,

src/main/resources/data/computercraft/lua/rom/programs/fun/advanced/paint.lua

@@ -163,7 +163,7 @@ local function save(path)
 end
 
 --[[
-    Draws colour picker sidebar, the pallette and the footer
+    Draws colour picker sidebar, the palette and the footer
     returns: nil
 ]]
 local function drawInterface()

src/main/resources/data/computercraft/lua/rom/programs/fun/adventure.lua

@@ -100,11 +100,11 @@ local items = {
     ["some wood"] = {
         aliases = { "wood" },
         material = true,
-        desc = "You could easilly craft this wood into planks.",
+        desc = "You could easily craft this wood into planks.",
     },
     ["some planks"] = {
         aliases = { "planks", "wooden planks", "wood planks" },
-        desc = "You could easilly craft these planks into sticks.",
+        desc = "You could easily craft these planks into sticks.",
     },
     ["some sticks"] = {
         aliases = { "sticks", "wooden sticks", "wood sticks" },
@@ -255,7 +255,7 @@ local items = {
     ["some pork"] = {
         aliases = { "pork", "porkchops" },
         food = true,
-        desc = "Delicious and nutricious.",
+        desc = "Delicious and nutritious.",
     },
     ["some chicken"] = {
         aliases = { "chicken" },
@@ -1144,7 +1144,7 @@ function commands.help()
     local sText =
         "Welcome to adventure, the greatest text adventure game on CraftOS. " ..
         "To get around the world, type actions, and the adventure will " ..
-        "be read back to you. The actions availiable to you are go, look, inspect, inventory, " ..
+        "be read back to you. The actions available to you are go, look, inspect, inventory, " ..
         "take, drop, place, punch, attack, mine, dig, craft, build, eat and exit."
     print(sText)
 end

src/main/resources/data/computercraft/lua/rom/programs/gps.lua

@@ -66,7 +66,7 @@ elseif sCommand == "host" then
     print("Opening channel on modem " .. sModemSide)
     modem.open(gps.CHANNEL_GPS)
 
-    -- Serve requests indefinately
+    -- Serve requests indefinitely
     local nServed = 0
     while true do
         local e, p1, p2, p3, p4, p5 = os.pullEvent("modem_message")

src/main/resources/data/computercraft/lua/rom/programs/import.lua

@@ -18,7 +18,5 @@ if #files == 0 then
   return
 end
 
-package.path = package.path .. "/rom/modules/internal/?.lua"
-
-local ok, err = require("cc.import")(files)
+local ok, err = require("cc.internal.import")(files)
 if not ok and err then printError(err) end

src/main/resources/data/computercraft/lua/rom/programs/lua.lua

@@ -6,13 +6,14 @@ if #tArgs > 0 then
 end
 
 local pretty = require "cc.pretty"
+local exception = require "cc.internal.exception"
 
-local bRunning = true
+local running = true
 local tCommandHistory = {}
 local tEnv = {
     ["exit"] = setmetatable({}, {
         __tostring = function() return "Call exit() to exit." end,
-        __call = function() bRunning = false end,
+        __call = function() running = false end,
     }),
     ["_echo"] = function(...)
         return ...
@@ -44,14 +45,15 @@ print("Interactive Lua prompt.")
 print("Call exit() to exit.")
 term.setTextColour(colours.white)
 
-while bRunning do
+local chunk_idx, chunk_map = 1, {}
+while running do
     --if term.isColour() then
     --    term.setTextColour( colours.yellow )
     --end
     write("lua> ")
     --term.setTextColour( colours.white )
 
-    local s = read(nil, tCommandHistory, function(sLine)
+    local input = read(nil, tCommandHistory, function(sLine)
         if settings.get("lua.autocomplete") then
             local nStartPos = string.find(sLine, "[a-zA-Z0-9_%.:]+$")
             if nStartPos then
@@ -63,10 +65,10 @@ while bRunning do
         end
         return nil
     end)
-    if s:match("%S") and tCommandHistory[#tCommandHistory] ~= s then
-        table.insert(tCommandHistory, s)
+    if input:match("%S") and tCommandHistory[#tCommandHistory] ~= input then
+        table.insert(tCommandHistory, input)
     end
-    if settings.get("lua.warn_against_use_of_local") and s:match("^%s*local%s+") then
+    if settings.get("lua.warn_against_use_of_local") and input:match("^%s*local%s+") then
         if term.isColour() then
             term.setTextColour(colours.yellow)
         end
@@ -74,27 +76,32 @@ while bRunning do
        term.setTextColour(colours.white)
     end
 
-    local nForcePrint = 0
-    local func, e = load(s, "=lua", "t", tEnv)
-    local func2 = load("return _echo(" .. s .. ");", "=lua", "t", tEnv)
+    local name, offset = "=lua[" .. chunk_idx .. "]", 0
+
+    local force_print = 0
+    local func, err = load(input, name, "t", tEnv)
+
+    local expr_func = load("return _echo(" .. input .. ");", name, "t", tEnv)
     if not func then
-        if func2 then
-            func = func2
-            e = nil
-            nForcePrint = 1
-        end
-    else
-        if func2 then
-            func = func2
+        if expr_func then
+            func = expr_func
+            offset = 13
+            force_print = 1
         end
+    elseif expr_func then
+        func = expr_func
+        offset = 13
     end
 
     if func then
-        local tResults = table.pack(pcall(func))
-        if tResults[1] then
+        chunk_map[name] = { contents = input, offset = offset }
+        chunk_idx = chunk_idx + 1
+
+        local results = table.pack(exception.try(func))
+        if results[1] then
             local n = 1
-            while n < tResults.n or n <= nForcePrint do
-                local value = tResults[n + 1]
+            while n < results.n or n <= force_print do
+                local value = results[n + 1]
                 local ok, serialised = pcall(pretty.pretty, value, {
                     function_args = settings.get("lua.function_args"),
                     function_source = settings.get("lua.function_source"),
@@ -107,10 +114,12 @@ while bRunning do
                 n = n + 1
             end
         else
-            printError(tResults[2])
+            printError(results[2])
+            require "cc.internal.exception".report(results[2], results[3], chunk_map)
         end
     else
-        printError(e)
+        local parser = require "cc.internal.syntax"
+        if parser.parse_repl(input) then printError(err) end
     end
 
 end

src/main/resources/data/computercraft/lua/rom/programs/pocket/falling.lua

@@ -446,7 +446,7 @@ local function playGame()
           end
         end
       end
-      --now remove the rows and drop everythign else
+      --now remove the rows and drop everything else
       term.setBackgroundColor(colors.black)
       for r = 1, #rows do
         r = rows[r]

src/main/resources/data/computercraft/lua/rom/programs/shell.lua

@@ -1,14 +1,32 @@
---- The shell API provides access to CraftOS's command line interface.
---
--- It allows you to @{run|start programs}, @{setCompletionFunction|add
--- completion for a program}, and much more.
---
--- @{shell} is not a "true" API. Instead, it is a standard program, which injects its
--- API into the programs that it launches. This allows for multiple shells to
--- run at the same time, but means that the API is not available in the global
--- environment, and so is unavailable to other @{os.loadAPI|APIs}.
---
--- @module[module] shell
+--[[- The shell API provides access to CraftOS's command line interface.
+
+It allows you to @{run|start programs}, @{setCompletionFunction|add completion
+for a program}, and much more.
+
+@{shell} is not a "true" API. Instead, it is a standard program, which injects
+its API into the programs that it launches. This allows for multiple shells to
+run at the same time, but means that the API is not available in the global
+environment, and so is unavailable to other @{os.loadAPI|APIs}.
+
+## Programs and the program path
+When you run a command with the shell, either from the prompt or
+@{shell.run|from Lua code}, the shell API performs several steps to work out
+which program to run:
+
+ 1. Firstly, the shell attempts to resolve @{shell.aliases|aliases}. This allows
+    us to use multiple names for a single command. For example, the `list`
+    program has two aliases: `ls` and `dir`. When you write `ls /rom`, that's
+    expanded to `list /rom`.
+
+ 2. Next, the shell attempts to find where the program actually is. For this, it
+    uses the @{shell.path|program path}. This is a colon separated list of
+    directories, each of which is checked to see if it contains the program.
+
+    `list` or `list.lua` doesn't exist in `.` (the current directory), so she
+    shell now looks in `/rom/programs`, where `list.lua` can be found!
+
+@module[module] shell
+]]
 
 local make_package = dofile("rom/modules/main/cc/require.lua").make
 
@@ -37,10 +55,11 @@ end
 -- Set up a dummy require based on the current shell, for loading some of our internal dependencies.
 local require
 do
-    local env = setmetatable(createShellEnv("/rom/modules/internal"), { __index = _ENV })
+    local env = setmetatable(createShellEnv("/rom/programs"), { __index = _ENV })
     require = env.require
 end
 local expect = require("cc.expect").expect
+local exception = require "cc.internal.exception"
 
 -- Colours
 local promptColour, textColour, bgColour
@@ -54,6 +73,69 @@ else
     bgColour = colours.black
 end
 
+local function tokenise(...)
+    local sLine = table.concat({ ... }, " ")
+    local tWords = {}
+    local bQuoted = false
+    for match in string.gmatch(sLine .. "\"", "(.-)\"") do
+        if bQuoted then
+            table.insert(tWords, match)
+        else
+            for m in string.gmatch(match, "[^ \t]+") do
+                table.insert(tWords, m)
+            end
+        end
+        bQuoted = not bQuoted
+    end
+    return tWords
+end
+
+local function executeProgram(path, args)
+    local file, err = fs.open(path, "r")
+    if not file then
+        printError(err)
+        return false
+    end
+
+    local contents = file.readAll() or ""
+    file.close()
+
+    local dir = fs.getDir(path)
+    local env = setmetatable(createShellEnv(dir), { __index = _G })
+    env.arg = args
+
+    local func, err = load(contents, "@/" .. path, nil, env)
+    if not func then
+        -- We had a syntax error. Attempt to run it through our own parser if
+        -- the file is "small enough", otherwise report the original error.
+        if #contents < 1024 * 128 then
+            local parser = require "cc.internal.syntax"
+            if parser.parse_program(contents) then printError(err) end
+        else
+            printError(err)
+        end
+
+        return false
+    end
+
+    if settings.get("bios.strict_globals", false) then
+        getmetatable(env).__newindex = function(_, name)
+            error("Attempt to create global " .. tostring(name), 2)
+        end
+    end
+
+    local ok, err, co = exception.try(func, table.unpack(args, 1, args.n))
+
+    if ok then return true end
+
+    if err and err ~= "" then
+        printError(err)
+        exception.report(err, co)
+    end
+
+    return false
+end
+
 --- Run a program with the supplied arguments.
 --
 -- Unlike @{shell.run}, each argument is passed to the program verbatim. While
@@ -84,10 +166,7 @@ function shell.execute(command, ...)
             multishell.setTitle(multishell.getCurrent(), sTitle)
         end
 
-        local sDir = fs.getDir(sPath)
-        local env = createShellEnv(sDir)
-        env.arg = { [0] = command, ... }
-        local result = os.run(env, sPath, ...)
+        local result = executeProgram(sPath, { [0] = command, ... })
 
         tProgramStack[#tProgramStack] = nil
         if multishell then
@@ -108,23 +187,6 @@ function shell.execute(command, ...)
     end
 end
 
-local function tokenise(...)
-    local sLine = table.concat({ ... }, " ")
-    local tWords = {}
-    local bQuoted = false
-    for match in string.gmatch(sLine .. "\"", "(.-)\"") do
-        if bQuoted then
-            table.insert(tWords, match)
-        else
-            for m in string.gmatch(match, "[^ \t]+") do
-                table.insert(tWords, m)
-            end
-        end
-        bQuoted = not bQuoted
-    end
-    return tWords
-end
-
 -- Install shell API
 
 --- Run a program with the supplied arguments.
@@ -247,6 +309,7 @@ end
 -- @treturn string|nil The absolute path to the program, or @{nil} if it could
 -- not be found.
 -- @since 1.2
+-- @changed 1.80pr1 Now searches for files with and without the `.lua` extension.
 -- @usage Locate the `hello` program.
 --
 --      shell.resolveProgram("hello")
@@ -541,8 +604,8 @@ end
 --- Get the current aliases for this shell.
 --
 -- Aliases are used to allow multiple commands to refer to a single program. For
--- instance, the `list` program is aliased `dir` or `ls`. Running `ls`, `dir` or
--- `list` in the shell will all run the `list` program.
+-- instance, the `list` program is aliased to `dir` or `ls`. Running `ls`, `dir`
+-- or `list` in the shell will all run the `list` program.
 --
 -- @treturn { [string] = string } A table, where the keys are the names of
 -- aliases, and the values are the path to the program.
@@ -655,7 +718,7 @@ else
                 term.setCursorBlink(false)
 
                 -- Run the import script with the provided files
-                local ok, err = require("cc.import")(event[2].getFiles())
+                local ok, err = require("cc.internal.import")(event[2].getFiles())
                 if not ok and err then printError(err) end
 
                 -- And attempt to restore the prompt.

src/main/resources/data/computercraft/lua/rom/programs/turtle/excavate.lua

@@ -93,13 +93,13 @@ local function collect()
     return true
 end
 
-function refuel(ammount)
+function refuel(amount)
     local fuelLevel = turtle.getFuelLevel()
     if fuelLevel == "unlimited" then
         return true
     end
 
-    local needed = ammount or xPos + zPos + depth + 2
+    local needed = amount or xPos + zPos + depth + 2
     if turtle.getFuelLevel() < needed then
         for n = 1, 16 do
             if turtle.getItemCount(n) > 0 then

src/test/java/dan200/computercraft/core/ComputerTestDelegate.java

@@ -5,7 +5,6 @@
  */
 package dan200.computercraft.core;
 
-import dan200.computercraft.ComputerCraft;
 import dan200.computercraft.api.filesystem.IWritableMount;
 import dan200.computercraft.api.lua.ILuaAPI;
 import dan200.computercraft.api.lua.LuaException;
@@ -15,22 +14,30 @@ import dan200.computercraft.core.computer.Computer;
 import dan200.computercraft.core.computer.ComputerSide;
 import dan200.computercraft.core.filesystem.FileMount;
 import dan200.computercraft.core.filesystem.FileSystemException;
+import dan200.computercraft.core.lua.CobaltLuaMachine;
+import dan200.computercraft.core.lua.MachineEnvironment;
+import dan200.computercraft.core.lua.MachineResult;
 import dan200.computercraft.core.terminal.Terminal;
 import dan200.computercraft.support.TestFiles;
 import dan200.computercraft.test.core.computer.BasicEnvironment;
 import dan200.computercraft.test.core.computer.FakeMainThreadScheduler;
-import org.apache.logging.log4j.LogManager;
-import org.apache.logging.log4j.Logger;
+import it.unimi.dsi.fastutil.ints.Int2IntArrayMap;
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
 import org.junit.jupiter.api.*;
 import org.junit.jupiter.api.function.Executable;
 import org.opentest4j.AssertionFailedError;
+import org.opentest4j.TestAbortedException;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.squiddev.cobalt.*;
+import org.squiddev.cobalt.debug.DebugFrame;
+import org.squiddev.cobalt.debug.DebugHook;
+import org.squiddev.cobalt.debug.DebugState;
+import org.squiddev.cobalt.function.OneArgFunction;
 
-import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
-import java.io.BufferedWriter;
-import java.io.File;
-import java.io.IOException;
-import java.io.Writer;
+import java.io.*;
+import java.lang.reflect.Field;
 import java.net.URI;
 import java.nio.channels.Channels;
 import java.nio.channels.WritableByteChannel;
@@ -43,6 +50,7 @@ import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 /**
@@ -60,7 +68,7 @@ public class ComputerTestDelegate
 {
     private static final Path REPORT_PATH = TestFiles.get( "luacov.report.out" );
 
-    private static final Logger LOG = LogManager.getLogger( ComputerTestDelegate.class );
+    private static final Logger LOG = LoggerFactory.getLogger( ComputerTestDelegate.class );
 
     private static final long TICK_TIME = TimeUnit.MILLISECONDS.toNanos( 50 );
 
@@ -86,14 +94,12 @@ public class ComputerTestDelegate
 
     private final Condition hasFinished = lock.newCondition();
     private boolean finished = false;
-    private Map<String, Map<Double, Double>> finishedWith;
+    private final Map<LuaString, Int2IntArrayMap> coverage = new HashMap<>();
 
     @BeforeEach
     public void before() throws IOException
     {
-        ComputerCraft.logComputerErrors = true;
-
-        if( Files.deleteIfExists( REPORT_PATH ) ) ComputerCraft.log.info( "Deleted previous coverage report." );
+        if( Files.deleteIfExists( REPORT_PATH ) ) LOG.info( "Deleted previous coverage report." );
 
         Terminal term = new Terminal( 80, 100, true );
         IWritableMount mount = new FileMount( TestFiles.get( "mount" ).toFile(), 10_000_000 );
@@ -157,12 +163,14 @@ public class ComputerTestDelegate
             computer.shutdown();
         }
 
-        if( finishedWith != null )
+        if( !coverage.isEmpty() )
         {
             Files.createDirectories( REPORT_PATH.getParent() );
             try( BufferedWriter writer = Files.newBufferedWriter( REPORT_PATH ) )
             {
-                new LuaCoverage( finishedWith ).write( writer );
+                new LuaCoverage( coverage.entrySet().stream().collect( Collectors.toMap(
+                    x -> x.getKey().substring( 1 ).toString(), Map.Entry::getValue
+                ) ) ).write( writer );
             }
         }
     }
@@ -174,7 +182,7 @@ public class ComputerTestDelegate
         try
         {
             long remaining = TIMEOUT;
-            while( remaining > 0 & tests == null )
+            while( remaining > 0 && tests == null )
             {
                 tick();
                 if( hasTests.awaitNanos( TICK_TIME ) > 0 ) break;
@@ -231,7 +239,12 @@ public class ComputerTestDelegate
         void runs( String name, String uri, Executable executor )
         {
             if( this.executor != null ) throw new IllegalStateException( name + " is leaf node" );
-            if( children.containsKey( name ) ) throw new IllegalStateException( "Duplicate key for " + name );
+            if( children.containsKey( name ) )
+            {
+                int i = 1;
+                while( children.containsKey( name + i ) ) i++;
+                name = name + i;
+            }
 
             children.put( name, new DynamicNodeBuilder( name, uri, executor ) );
         }
@@ -290,7 +303,6 @@ public class ComputerTestDelegate
 
     public static class FakeModem implements IPeripheral
     {
-        @Nonnull
         @Override
         public String getType()
         {
@@ -312,7 +324,6 @@ public class ComputerTestDelegate
 
     public static class FakePeripheralHub implements IPeripheral
     {
-        @Nonnull
         @Override
         public String getType()
         {
@@ -464,10 +475,6 @@ public class ComputerTestDelegate
         {
             //  Submit the result of a test, allowing the test executor to continue
             String name = (String) tbl.get( "name" );
-            if( name == null )
-            {
-                ComputerCraft.log.error( "Oh no: {}", tbl );
-            }
             String status = (String) tbl.get( "status" );
             String message = (String) tbl.get( "message" );
             String trace = (String) tbl.get( "trace" );
@@ -502,7 +509,9 @@ public class ComputerTestDelegate
                 switch( status )
                 {
                     case "ok":
+                        break;
                     case "pending":
+                        runResult = new TestAbortedException( "Test is pending" );
                         break;
                     case "fail":
                         runResult = new AssertionFailedError( wholeMessage.toString() );
@@ -522,10 +531,8 @@ public class ComputerTestDelegate
         }
 
         @LuaFunction
-        public final void finish( Optional<Map<?, ?>> result )
+        public final void finish()
         {
-            @SuppressWarnings( "unchecked" )
-            Map<String, Map<Double, Double>> finishedResult = (Map<String, Map<Double, Double>>) result.orElse( null );
             LOG.info( "Finished" );
 
             // Signal to after that execution has finished
@@ -540,7 +547,6 @@ public class ComputerTestDelegate
             try
             {
                 finished = true;
-                if( finishedResult != null ) finishedWith = finishedResult;
 
                 hasFinished.signal();
             }
@@ -550,4 +556,86 @@ public class ComputerTestDelegate
             }
         }
     }
+
+    /**
+     * A subclass of {@link CobaltLuaMachine} which tracks coverage for executed files.
+     * <p>
+     * This is a super nasty hack, but is also an order of magnitude faster than tracking this in Lua.
+     */
+    private class CoverageLuaMachine extends CobaltLuaMachine
+    {
+        CoverageLuaMachine( MachineEnvironment environment )
+        {
+            super( environment );
+        }
+
+        @Override
+        public MachineResult loadBios( InputStream bios )
+        {
+            MachineResult result = super.loadBios( bios );
+            if( result != MachineResult.OK ) return result;
+
+            LuaTable globals;
+            LuaThread mainRoutine;
+            try
+            {
+                Field globalField = CobaltLuaMachine.class.getDeclaredField( "globals" );
+                globalField.setAccessible( true );
+                globals = (LuaTable) globalField.get( this );
+
+                Field threadField = CobaltLuaMachine.class.getDeclaredField( "mainRoutine" );
+                threadField.setAccessible( true );
+                mainRoutine = (LuaThread) threadField.get( this );
+            }
+            catch( ReflectiveOperationException e )
+            {
+                throw new RuntimeException( "Cannot get internal Cobalt state", e );
+            }
+
+            Map<LuaString, Int2IntArrayMap> coverage = ComputerTestDelegate.this.coverage;
+            DebugHook hook = new DebugHook()
+            {
+                @Override
+                public void onCall( LuaState state, DebugState ds, DebugFrame frame )
+                {
+                }
+
+                @Override
+                public void onReturn( LuaState state, DebugState ds, DebugFrame frame )
+                {
+                }
+
+                @Override
+                public void onCount( LuaState state, DebugState ds, DebugFrame frame )
+                {
+                }
+
+                @Override
+                public void onLine( LuaState state, DebugState ds, DebugFrame frame, int newLine )
+                {
+                    if( frame.closure == null ) return;
+
+                    Prototype proto = frame.closure.getPrototype();
+                    if( !proto.source.startsWith( '@' ) ) return;
+
+                    Int2IntMap map = coverage.computeIfAbsent( proto.source, x -> new Int2IntArrayMap() );
+                    map.put( newLine, map.get( newLine ) + 1 );
+                }
+            };
+
+            ((LuaTable) globals.rawget( "coroutine" )).rawset( "create", new OneArgFunction()
+            {
+                @Override
+                public LuaValue call( LuaState state, LuaValue arg ) throws LuaError
+                {
+                    LuaThread thread = new LuaThread( state, arg.checkFunction(), state.getCurrentThread().getfenv() );
+                    thread.getDebugState().setHook( hook, false, true, false, 0 );
+                    return thread;
+                }
+            } );
+            mainRoutine.getDebugState().setHook( hook, false, true, false, 0 );
+
+            return MachineResult.OK;
+        }
+    }
 }

src/test/java/dan200/computercraft/core/LuaCoverage.java

@@ -6,9 +6,12 @@
 package dan200.computercraft.core;
 
 import com.google.common.base.Strings;
-import dan200.computercraft.ComputerCraft;
+import it.unimi.dsi.fastutil.ints.Int2IntMap;
+import it.unimi.dsi.fastutil.ints.Int2IntMaps;
 import it.unimi.dsi.fastutil.ints.IntOpenHashSet;
 import it.unimi.dsi.fastutil.ints.IntSet;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.squiddev.cobalt.Prototype;
 import org.squiddev.cobalt.compiler.CompileException;
 import org.squiddev.cobalt.compiler.LuaC;
@@ -16,30 +19,27 @@ import org.squiddev.cobalt.compiler.LuaC;
 import java.io.*;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.*;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
+import java.util.ArrayDeque;
+import java.util.Collections;
+import java.util.Map;
+import java.util.Queue;
 
 class LuaCoverage
 {
+    private static final Logger LOG = LoggerFactory.getLogger( LuaCoverage.class );
     private static final Path ROOT = new File( "src/main/resources/data/computercraft/lua" ).toPath();
-    private static final Path BIOS = ROOT.resolve( "bios.lua" );
-    private static final Path APIS = ROOT.resolve( "rom/apis" );
-    private static final Path SHELL = ROOT.resolve( "rom/programs/shell.lua" );
-    private static final Path MULTISHELL = ROOT.resolve( "rom/programs/advanced/multishell.lua" );
-    private static final Path TREASURE = ROOT.resolve( "treasure" );
 
-    private final Map<String, Map<Double, Double>> coverage;
+    private final Map<String, Int2IntMap> coverage;
     private final String blank;
     private final String zero;
     private final String countFormat;
 
-    LuaCoverage( Map<String, Map<Double, Double>> coverage )
+    LuaCoverage( Map<String, Int2IntMap> coverage )
     {
         this.coverage = coverage;
 
-        int max = (int) coverage.values().stream()
-            .flatMapToDouble( x -> x.values().stream().mapToDouble( y -> y ) )
+        int max = coverage.values().stream()
+            .flatMapToInt( x -> x.values().stream().mapToInt( y -> y ) )
             .max().orElse( 0 );
         int maxLen = Math.max( 1, (int) Math.ceil( Math.log10( max ) ) );
         blank = Strings.repeat( " ", maxLen + 1 );
@@ -49,25 +49,22 @@ class LuaCoverage
 
     void write( Writer out ) throws IOException
     {
-        Files.find( ROOT, Integer.MAX_VALUE, ( path, attr ) -> attr.isRegularFile() && !path.startsWith( TREASURE ) ).forEach( path -> {
+        Files.find( ROOT, Integer.MAX_VALUE, ( path, attr ) -> attr.isRegularFile() ).forEach( path -> {
             Path relative = ROOT.relativize( path );
             String full = relative.toString().replace( '\\', '/' );
             if( !full.endsWith( ".lua" ) ) return;
 
-            Map<Double, Double> files = Stream.of(
-                coverage.remove( "/" + full ),
-                path.equals( BIOS ) ? coverage.remove( "bios.lua" ) : null,
-                path.equals( SHELL ) ? coverage.remove( "shell.lua" ) : null,
-                path.equals( MULTISHELL ) ? coverage.remove( "multishell.lua" ) : null,
-                path.startsWith( APIS ) ? coverage.remove( path.getFileName().toString() ) : null
-            )
-                .filter( Objects::nonNull )
-                .flatMap( x -> x.entrySet().stream() )
-                .collect( Collectors.toMap( Map.Entry::getKey, Map.Entry::getValue, Double::sum ) );
+            Int2IntMap possiblePaths = coverage.remove( "/" + full );
+            if( possiblePaths == null ) possiblePaths = coverage.remove( full );
+            if( possiblePaths == null )
+            {
+                possiblePaths = Int2IntMaps.EMPTY_MAP;
+                LOG.warn( "{} has no coverage data", full );
+            }
 
             try
             {
-                writeCoverageFor( out, path, files );
+                writeCoverageFor( out, path, possiblePaths );
             }
             catch( IOException e )
             {
@@ -78,15 +75,15 @@ class LuaCoverage
         for( String filename : coverage.keySet() )
         {
             if( filename.startsWith( "/test-rom/" ) ) continue;
-            ComputerCraft.log.warn( "Unknown file {}", filename );
+            LOG.warn( "Unknown file {}", filename );
         }
     }
 
-    private void writeCoverageFor( Writer out, Path fullName, Map<Double, Double> visitedLines ) throws IOException
+    private void writeCoverageFor( Writer out, Path fullName, Int2IntMap visitedLines ) throws IOException
     {
         if( !Files.exists( fullName ) )
         {
-            ComputerCraft.log.error( "Cannot locate file {}", fullName );
+            LOG.error( "Cannot locate file {}", fullName );
             return;
         }
 
@@ -104,10 +101,10 @@ class LuaCoverage
             while( (line = reader.readLine()) != null )
             {
                 lineNo++;
-                Double count = visitedLines.get( (double) lineNo );
-                if( count != null )
+                int count = visitedLines.getOrDefault( lineNo, -1 );
+                if( count >= 0 )
                 {
-                    out.write( String.format( countFormat, count.intValue() ) );
+                    out.write( String.format( countFormat, count ) );
                 }
                 else if( activeLines.contains( lineNo ) )
                 {
@@ -128,30 +125,32 @@ class LuaCoverage
     private static IntSet getActiveLines( File file ) throws IOException
     {
         IntSet activeLines = new IntOpenHashSet();
-        try( InputStream stream = new FileInputStream( file ) )
+        Queue<Prototype> queue = new ArrayDeque<>();
+
+        try( InputStream stream = Files.newInputStream( file.toPath() ) )
         {
             Prototype proto = LuaC.compile( stream, "@" + file.getPath() );
-            Queue<Prototype> queue = new ArrayDeque<>();
             queue.add( proto );
-
-            while( (proto = queue.poll()) != null )
-            {
-                int[] lines = proto.lineinfo;
-                if( lines != null )
-                {
-                    for( int line : lines )
-                    {
-                        activeLines.add( line );
-                    }
-                }
-                if( proto.p != null ) Collections.addAll( queue, proto.p );
-            }
         }
         catch( CompileException e )
         {
             throw new IllegalStateException( "Cannot compile", e );
         }
 
+        Prototype proto;
+        while( (proto = queue.poll()) != null )
+        {
+            int[] lines = proto.lineInfo;
+            if( lines != null )
+            {
+                for( int line : lines )
+                {
+                    activeLines.add( line );
+                }
+            }
+            if( proto.children != null ) Collections.addAll( queue, proto.children );
+        }
+
         return activeLines;
     }
 }

src/test/java/dan200/computercraft/core/computer/ComputerTest.java

@@ -29,7 +29,7 @@ public class ComputerTest
             }
             catch( AssertionError e )
             {
-                if( e.getMessage().equals( "test.lua:1: Too long without yielding" ) ) return;
+                if( e.getMessage().equals( "/test.lua:1: Too long without yielding" ) ) return;
                 throw e;
             }
 

src/test/java/dan200/computercraft/core/filesystem/FileSystemTest.java

@@ -12,6 +12,8 @@ import dan200.computercraft.core.apis.ObjectWrapper;
 import dan200.computercraft.core.apis.handles.EncodedWritableHandle;
 import dan200.computercraft.support.TestFiles;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
 
 import java.io.BufferedWriter;
 import java.io.File;
@@ -79,4 +81,23 @@ public class FileSystemTest
         LuaException err = assertThrows( LuaException.class, () -> wrapper.call( "write", "Tiny line" ) );
         assertEquals( "attempt to use a closed file", err.getMessage() );
     }
+
+    @ParameterizedTest( name = "{0}" )
+    @MethodSource( "sanitiseCases" )
+    public void testSanitize( String input, String output )
+    {
+        assertEquals( output, FileSystem.sanitizePath( input, false ) );
+    }
+
+    public static String[][] sanitiseCases()
+    {
+        return new String[][] {
+            new String[] { "a//b", "a/b" },
+            new String[] { "a/./b", "a/b" },
+            new String[] { "a/../b", "b" },
+            new String[] { "a/.../b", "a/b" },
+            new String[] { " a ", "a" },
+            new String[] { "a b c", "a b c" },
+        };
+    }
 }

src/test/resources/test-rom/data/json-parsing/README.md

@@ -1,7 +1,7 @@
 # JSON Parsing Test Suite
 
 This is a collection of JSON test cases from [nst/JSONTestSuite][gh]. We simply
-determine whether an object is succesfully parsed or not, and do not check the
+determine whether an object is successfully parsed or not, and do not check the
 contents.
 
 See `LICENSE` for copyright information.

src/test/resources/test-rom/mcfly.lua

@@ -182,8 +182,12 @@ end
 -- @treturn string The formatted value
 local function format(value)
     -- TODO: Look into something like mbs's pretty printer.
-    local ok, res = pcall(textutils.serialise, value)
-    if ok then return res else return tostring(value) end
+    if type(value) == "string" and value:find("\n") then
+        return "<<<\n" .. value .. "\n>>>"
+    else
+        local ok, res = pcall(textutils.serialise, value)
+        if ok then return res else return tostring(value) end
+    end
 end
 
 local expect_mt = {}
@@ -417,6 +421,9 @@ end
 --- The stack of "describe"s.
 local test_stack = { n = 0 }
 
+--- The stack of setup functions.
+local before_each_fns = { n = 0 }
+
 --- Whether we're now running tests, and so cannot run any more.
 local tests_locked = false
 
@@ -455,8 +462,14 @@ local function describe(name, body)
     local n = test_stack.n + 1
     test_stack[n], test_stack.n = name, n
 
+    local old_before, new_before = before_each_fns, { n = before_each_fns.n }
+    for i = 1, old_before.n do new_before[i] = old_before[i] end
+    before_each_fns = new_before
+
     local ok, err = try(body)
 
+    before_each_fns = old_before
+
     -- We count errors as a (failing) test.
     if not ok then do_test { error = err, definition = format_loc(debug.getinfo(2, "Sl")) } end
 
@@ -477,7 +490,11 @@ local function it(name, body)
     local n = test_stack.n + 1
     test_stack[n], test_stack.n, tests_locked = name, n, true
 
-    do_test { action = body, definition = format_loc(debug.getinfo(2, "Sl")) }
+    do_test {
+        action = body,
+        before = before_each_fns,
+        definition = format_loc(debug.getinfo(2, "Sl")),
+    }
 
     -- Pop the test from the stack
     test_stack.n, tests_locked = n - 1, false
@@ -498,26 +515,17 @@ local function pending(name)
     test_stack.n = n - 1
 end
 
-local native_co_create, native_loadfile = coroutine.create, loadfile
+local function before_each(body)
+    check('it', 1, 'function', body)
+    if tests_locked then error("Cannot define before_each while running tests", 2) end
+
+    local n = before_each_fns.n + 1
+    before_each_fns[n], before_each_fns.n = body, n
+end
+
+local native_loadfile = loadfile
 local line_counts = {}
 if cct_test then
-    local string_sub, debug_getinfo = string.sub, debug.getinfo
-    local function debug_hook(_, line_nr)
-        local name = debug_getinfo(2, "S").source
-        if string_sub(name, 1, 1) ~= "@" then return end
-        name = string_sub(name, 2)
-
-        local file = line_counts[name]
-        if not file then file = {} line_counts[name] = file end
-        file[line_nr] = (file[line_nr] or 0) + 1
-    end
-
-    coroutine.create = function(...)
-        local co = native_co_create(...)
-        debug.sethook(co, debug_hook, "l")
-        return co
-    end
-
     local expect = require "cc.expect".expect
     _G.native_loadfile = native_loadfile
     _G.loadfile = function(filename, mode, env)
@@ -537,8 +545,6 @@ if cct_test then
         file.close()
         return func, err
     end
-
-    debug.sethook(debug_hook, "l")
 end
 
 local arg = ...
@@ -559,16 +565,11 @@ end
 package.path = ("/%s/?.lua;/%s/?/init.lua;%s"):format(root_dir, root_dir, package.path)
 
 do
-    -- Load in the tests from all our files
-    local env = setmetatable({}, { __index = _ENV })
-
-    local function set_env(tbl)
-        for k in pairs(env) do env[k] = nil end
-        for k, v in pairs(tbl) do env[k] = v end
-    end
-
-    -- When declaring tests, you shouldn't be able to use test methods
-    set_env { describe = describe, it = it, pending = pending }
+    -- Add our new functions to the current environment.
+    for k, v in pairs {
+        describe = describe, it = it, pending = pending, before_each = before_each,
+        expect = expect, fail = fail,
+    } do _ENV[k] = v end
 
     local suffix = "_spec.lua"
     local function run_in(sub_dir)
@@ -577,7 +578,7 @@ do
             if fs.isDir(file) then
                 run_in(file)
             elseif file:sub(-#suffix) == suffix then
-                local fun, err = loadfile(file, nil, env)
+                local fun, err = loadfile(file, nil, _ENV)
                 if not fun then
                     do_test { name = file:sub(#root_dir + 2), error = { message = err } }
                 else
@@ -590,8 +591,8 @@ do
 
     run_in(root_dir)
 
-    -- When running tests, you shouldn't be able to declare new ones.
-    set_env { expect = expect, fail = fail, stub = stub }
+    -- Add stub later on, so its not available when running tests
+    _ENV.stub = stub
 end
 
 -- Error if we've found no tests
@@ -630,8 +631,13 @@ local function do_run(test)
         -- Flush the event queue and ensure we're running with 0 timeout.
         os.queueEvent("start_test") os.pullEvent("start_test")
 
-        local ok
-        ok, err = try(test.action)
+        local ok = true
+        for i = 1, test.before.n do
+            if not ok then break end
+            ok, err = try(test.before[i])
+        end
+        if ok then ok, err = try(test.action) end
+
         status = ok and "pass" or (err.fail and "fail" or "error")
 
         pop_state(state)
@@ -711,8 +717,6 @@ end
 term.setTextColour(colours.white) io.write(info .. "\n")
 
 -- Restore hook stubs
-debug.sethook(nil, "l")
-coroutine.create = native_co_create
 _G.loadfile = native_loadfile
 
 if cct_test then cct_test.finish(line_counts) end

src/test/resources/test-rom/spec/apis/fs_spec.lua

@@ -1,4 +1,8 @@
 describe("The fs library", function()
+    local test_root = "/test-files/fs"
+    local function test_file(path) return fs.combine(test_root, path) end
+    before_each(function() fs.delete(test_root) end)
+
     describe("fs.complete", function()
         it("validates arguments", function()
             fs.complete("", "")
@@ -139,7 +143,7 @@ describe("The fs library", function()
             end)
 
             it("errors when closing twice", function()
-                local handle = fs.open("test-files/out.txt", "w")
+                local handle = fs.open(test_file "out.txt", "w")
                 handle.close()
                 expect.error(handle.close):eq("attempt to use a closed file")
             end)
@@ -216,6 +220,48 @@ describe("The fs library", function()
             expect.error(fs.move, "test-files", "rom/move"):eq("Access denied")
             expect.error(fs.move, "rom", "test-files"):eq("Access denied")
         end)
+
+        it("fails if source does not exist", function()
+            expect.error(fs.move, test_file "src", test_file "dest"):eq("No such file")
+        end)
+
+        it("fails if destination exists", function()
+            fs.open(test_file "src", "w").close()
+            fs.open(test_file "dest", "w").close()
+
+            expect.error(fs.move, test_file "src", test_file "dest"):eq("File exists")
+        end)
+
+        it("fails to move a directory inside itself", function()
+            fs.open(test_file "file", "w").close()
+            expect.error(fs.move, test_root, test_file "child"):eq("Can't move a directory inside itself")
+            expect.error(fs.move, "", "child"):eq("Can't move a directory inside itself")
+        end)
+
+        it("files can be renamed", function()
+            fs.open(test_file "src", "w").close()
+            fs.move(test_file "src",  test_file "dest")
+
+            expect(fs.exists(test_file "src")):eq(false)
+            expect(fs.exists(test_file "dest")):eq(true)
+        end)
+
+        it("directories can be renamed", function()
+            fs.open(test_file "src/some/file", "w").close()
+            fs.move(test_file "src",  test_file "dest")
+
+            expect(fs.exists(test_file "src")):eq(false)
+            expect(fs.exists(test_file "dest")):eq(true)
+            expect(fs.exists(test_file "dest/some/file")):eq(true)
+        end)
+
+        it("creates directories before renaming", function()
+            fs.open(test_file "src", "w").close()
+            fs.move(test_file "src", test_file "dest/file")
+
+            expect(fs.exists(test_file "src")):eq(false)
+            expect(fs.exists(test_file "dest/file")):eq(true)
+        end)
     end)
 
     describe("fs.getCapacity", function()
@@ -240,12 +286,11 @@ describe("The fs library", function()
         it("returns information about files", function()
             local now = os.epoch("utc")
 
-            fs.delete("/tmp/basic-file")
-            local h = fs.open("/tmp/basic-file", "w")
+            local h = fs.open(test_file "basic-file", "w")
             h.write("A reasonably sized string")
             h.close()
 
-            local attributes = fs.attributes("tmp/basic-file")
+            local attributes = fs.attributes(test_file "basic-file")
             expect(attributes):matches { isDir = false, size = 25, isReadOnly = false }
 
             if attributes.created - now >= 1000 then

src/test/resources/test-rom/spec/apis/http_spec.lua

@@ -1,3 +1,5 @@
+local timeout = require "test_helpers".timeout
+
 describe("The http library", function()
     describe("http.checkURL", function()
         it("accepts well formed domains", function()
@@ -18,4 +20,28 @@ describe("The http library", function()
             expect({ http.checkURL("http://127.0.0.1") }):same({ false, "Domain not permitted" })
         end)
     end)
+
+    describe("http.websocketAsync", function()
+        it("queues an event for immediate failures", function()
+            timeout(1, function()
+                local url = "http://not.a.websocket"
+                http.websocketAsync(url)
+                local _, url2, message = os.pullEvent("websocket_failure")
+                expect(url2):eq(url)
+                expect(message):eq("Invalid scheme 'http'")
+            end)
+        end)
+    end)
+
+    describe("http.requestAsync", function()
+        it("queues an event for immediate failures", function()
+            timeout(1, function()
+                local url = "ws://not.a.request"
+                http.request(url)
+                local _, url2, message = os.pullEvent("http_failure")
+                expect(url2):eq(url)
+                expect(message):eq("Invalid protocol 'ws'")
+            end)
+        end)
+    end)
 end)

src/test/resources/test-rom/spec/apis/os_spec.lua

@@ -96,6 +96,9 @@ describe("The os library", function()
             exp_code("%Y", "2000")
             exp_code("%%", "%")
 
+            it("%r at 12 AM", function() expect(os.date("%r", 1670373922)):eq("12:45:22 AM") end)
+            it("%I at 12 AM", function() expect(os.date("%I", 1670373922)):eq("12") end)
+
             it("zones are numbers", function()
                 local zone = os.date("%z", t1)
                 if not zone:match("^[+-]%d%d%d%d$") then

src/test/resources/test-rom/spec/apis/rednet_spec.lua

@@ -37,6 +37,14 @@ describe("The rednet library", function()
             expect.error(rednet.send, nil):eq("bad argument #1 (expected number, got nil)")
             expect.error(rednet.send, 1, nil, false):eq("bad argument #3 (expected string, got boolean)")
         end)
+
+        it("queues an event on the current computer", function()
+            rednet.send(os.getComputerID(), "Test message")
+            local id, message = rednet.receive(1.0)
+
+            expect(id):eq(os.getComputerID())
+            expect(message):eq("Test message")
+        end)
     end)
 
     describe("rednet.broadcast", function()

src/test/resources/test-rom/spec/base_spec.lua

@@ -28,8 +28,6 @@ describe("The Lua base library", function()
     end)
 
     describe("loadfile", function()
-        local loadfile = _G.native_loadfile or loadfile
-
         local function make_file()
             local tmp = fs.open("test-files/out.lua", "w")
             tmp.write("return _ENV")
@@ -48,7 +46,7 @@ describe("The Lua base library", function()
 
         it("prefixes the filename with @", function()
             local info = debug.getinfo(loadfile("/rom/startup.lua"), "S")
-            expect(info):matches { short_src = "startup.lua", source = "@startup.lua" }
+            expect(info):matches { short_src = "/rom/startup.lua", source = "@/rom/startup.lua" }
         end)
 
         it("loads a file with the global environment", function()

src/test/resources/test-rom/spec/modules/cc/internal/syntax/init_spec.lua

@@ -0,0 +1,52 @@
+local helpers = require "test_helpers"
+
+describe("cc.internal.syntax", function()
+    local syntax = require "cc.internal.syntax"
+    local parser = require "cc.internal.syntax.parser"
+    local syntax_helpers = require "modules.cc.internal.syntax.syntax_helpers"
+
+    describe("can parse all of CC's Lua files", function()
+        local function list_dir(path)
+            if not path then path = "/" end
+            for _, child in pairs(fs.list(path)) do
+                child = fs.combine(path, child)
+
+                if fs.isDir(child) then list_dir(child)
+                elseif child:sub(-4) == ".lua" then coroutine.yield(child)
+                end
+            end
+        end
+
+        for file in coroutine.wrap(list_dir) do
+            it(file, function()
+                helpers.with_window(50, 10, function()
+                    local h = fs.open(file, "r")
+                    local contents = h.readAll()
+                    h.close()
+
+                    expect(syntax.parse_program(contents)):describe(file):eq(true)
+                end)
+            end)
+        end
+    end)
+
+    -- We specify most of the parser's behaviour as golden tests. A little nasty
+    -- (it's more of an end-to-end test), but much easier to write!
+    local function describe_golden(name, path, print_tokens)
+        helpers.describe_golden(name, "test-rom/spec/modules/cc/internal/syntax/" .. path, function(lua, extra)
+            local start = nil
+            if #extra > 0 then
+                start = parser[extra:match("^{([a-z_]+)}$")]
+                if not start then
+                    fail("Cannot extract start symbol " .. extra)
+                end
+            end
+
+            return syntax_helpers.capture_parser(lua, print_tokens, start)
+        end)
+    end
+
+    describe_golden("the lexer", "lexer_spec.md", true)
+    describe_golden("the parser", "parser_spec.md", false)
+    describe_golden("the parser (all states)", "parser_exhaustive_spec.md", false)
+end)

src/test/resources/test-rom/spec/modules/cc/internal/syntax/lexer_spec.md

@@ -0,0 +1,319 @@
+We provide a lexer for Lua source code. Here we test that the lexer returns the
+correct tokens and positions, and that it can report sensible error messages.
+
+# Comments
+
+## Single-line comments
+We can lex some basic comments:
+
+```lua
+-- A basic singleline comment comment
+--[ Not a multiline comment
+--[= Also not a multiline comment!
+```
+
+```txt
+1:1-1:37 COMMENT -- A basic singleline comment comment
+2:1-2:27 COMMENT --[ Not a multiline comment
+3:1-3:34 COMMENT --[= Also not a multiline comment!
+```
+
+It's also useful to test empty comments (including no trailing newline) separately:
+
+```lua
+--
+```
+
+```txt
+1:1-1:2 COMMENT --
+```
+
+## Multi-line comments
+Multiline/long-string-style comments are also supported:
+
+```lua
+--[[
+  A
+  multiline
+  comment
+]]
+
+--[=[  ]==] ]] ]=]
+
+--[[ ]=]]
+```
+
+```txt
+1:1-5:2 COMMENT --[[<NL>  A<NL>  multiline<NL>  comment<NL>]]
+7:1-7:18 COMMENT --[=[  ]==] ]] ]=]
+9:1-9:9 COMMENT --[[ ]=]]
+```
+
+We also fail on unfinished comments:
+
+```lua
+--[=[
+```
+
+```txt
+This comment was never finished.
+   |
+ 1 | --[=[
+   | ^^^^^ Comment was started here.
+We expected a closing delimiter (]=]) somewhere after this comment was started.
+1:1-1:5 ERROR --[=[
+```
+
+Nested comments are rejected, just as Lua 5.1 does:
+
+```lua
+--[[ [[ ]]
+```
+
+```txt
+[[ cannot be nested inside another [[ ... ]]
+   |
+ 1 | --[[ [[ ]]
+   |      ^^
+1:1-1:10 COMMENT --[[ [[ ]]
+```
+
+# Strings
+
+We can lex basic strings:
+
+```lua
+return "abc", "abc\"", 'abc', 'abc\z
+
+', "abc\
+continued"
+```
+
+```txt
+1:1-1:6 RETURN return
+1:8-1:12 STRING "abc"
+1:13-1:13 COMMA ,
+1:15-1:21 STRING "abc\""
+1:22-1:22 COMMA ,
+1:24-1:28 STRING 'abc'
+1:29-1:29 COMMA ,
+1:31-3:1 STRING 'abc\z<NL><NL>'
+3:2-3:2 COMMA ,
+3:4-4:10 STRING "abc\<NL>continued"
+```
+
+We also can lex unterminated strings, including those where there's no closing
+quote:
+
+```lua
+return "abc
+```
+
+```txt
+1:1-1:6 RETURN return
+This string is not finished. Are you missing a closing quote (")?
+   |
+ 1 | return "abc
+   |        ^ String started here.
+   |
+ 1 | return "abc
+   |            ^ Expected a closing quote here.
+1:8-1:11 STRING "abc
+```
+
+And those where the zap is malformed:
+
+```lua
+return "abc\z
+
+```
+
+```txt
+1:1-1:6 RETURN return
+This string is not finished. Are you missing a closing quote (")?
+   |
+ 1 | return "abc\z
+   |        ^ String started here.
+   |
+ 1 | return "abc\z
+   |              ^ Expected a closing quote here.
+1:8-1:14 STRING "abc\z<NL>
+```
+
+Finally, strings where the escape is entirely missing:
+
+```lua
+return "abc\
+```
+
+```txt
+1:1-1:6 RETURN return
+This string is not finished.
+   |
+ 1 | return "abc\
+   |        ^ String started here.
+   |
+ 1 | return "abc\
+   |            ^ An escape sequence was started here, but with nothing following it.
+1:8-1:12 STRING "abc\
+```
+
+## Multi-line/long strings
+We can also handle long strings fine
+
+```lua
+return [[a b c]], [=[a b c ]=]
+```
+
+```txt
+1:1-1:6 RETURN return
+1:8-1:16 STRING [[a b c]]
+1:17-1:17 COMMA ,
+1:19-1:30 STRING [=[a b c ]=]
+```
+
+Unfinished long strings are correctly reported:
+
+```lua
+return [[
+```
+
+```txt
+1:1-1:6 RETURN return
+This string was never finished.
+   |
+ 1 | return [[
+   |        ^^ String was started here.
+We expected a closing delimiter (]]) somewhere after this string was started.
+1:8-1:9 ERROR [[
+```
+
+We also handle malformed opening strings:
+
+```lua
+return [=
+```
+
+```txt
+1:1-1:6 RETURN return
+Incorrect start of a long string.
+   |
+ 1 | return [=
+   |        ^^^
+Tip: If you wanted to start a long string here, add an extra [ here.
+1:8-1:10 ERROR [=
+```
+
+# Numbers
+
+```lua
+return 0, 0.0, 0e1, .23, 0x23, 23e-2, 23e+2
+```
+
+```txt
+1:1-1:6 RETURN return
+1:8-1:8 NUMBER 0
+1:9-1:9 COMMA ,
+1:11-1:13 NUMBER 0.0
+1:14-1:14 COMMA ,
+1:16-1:18 NUMBER 0e1
+1:19-1:19 COMMA ,
+1:21-1:23 NUMBER .23
+1:24-1:24 COMMA ,
+1:26-1:29 NUMBER 0x23
+1:30-1:30 COMMA ,
+1:32-1:36 NUMBER 23e-2
+1:37-1:37 COMMA ,
+1:39-1:43 NUMBER 23e+2
+```
+
+We also handle malformed numbers:
+
+```lua
+return 2..3, 2eee2
+```
+
+```txt
+1:1-1:6 RETURN return
+This isn't a valid number.
+   |
+ 1 | return 2..3, 2eee2
+   |        ^^^^
+Numbers must be in one of the following formats: 123, 3.14, 23e35, 0x01AF.
+1:8-1:11 NUMBER 2..3
+1:12-1:12 COMMA ,
+This isn't a valid number.
+   |
+ 1 | return 2..3, 2eee2
+   |              ^^^^^
+Numbers must be in one of the following formats: 123, 3.14, 23e35, 0x01AF.
+1:14-1:18 NUMBER 2eee2
+```
+
+# Unknown tokens
+
+We can suggest alternatives for possible errors:
+
+```lua
+if a != b then end
+if a ~= b then end
+if a && b then end
+if a || b then end
+```
+
+```txt
+1:1-1:2 IF if
+1:4-1:4 IDENT a
+Unexpected character.
+   |
+ 1 | if a != b then end
+   |      ^^
+Tip: Replace this with ~= to check if two values are not equal.
+1:6-1:7 NE !=
+1:9-1:9 IDENT b
+1:11-1:14 THEN then
+1:16-1:18 END end
+2:1-2:2 IF if
+2:4-2:4 IDENT a
+2:6-2:7 NE ~=
+2:9-2:9 IDENT b
+2:11-2:14 THEN then
+2:16-2:18 END end
+3:1-3:2 IF if
+3:4-3:4 IDENT a
+Unexpected character.
+   |
+ 3 | if a && b then end
+   |      ^^
+Tip: Replace this with and to check if both values are true.
+3:6-3:7 AND &&
+3:9-3:9 IDENT b
+3:11-3:14 THEN then
+3:16-3:18 END end
+4:1-4:2 IF if
+4:4-4:4 IDENT a
+Unexpected character.
+   |
+ 4 | if a || b then end
+   |      ^^
+Tip: Replace this with or to check if either value is true.
+4:6-4:7 OR ||
+4:9-4:9 IDENT b
+4:11-4:14 THEN then
+4:16-4:18 END end
+```
+
+For entirely unknown glyphs we should just give up and return an `ERROR` token.
+
+```lua
+return $*&(*)xyz
+```
+
+```txt
+1:1-1:6 RETURN return
+Unexpected character.
+   |
+ 1 | return $*&(*)xyz
+   |        ^ This character isn't usable in Lua code.
+1:8-1:10 ERROR $*&
+```

src/test/resources/test-rom/spec/modules/cc/internal/syntax/parser_spec.md

@@ -0,0 +1,370 @@
+We provide a parser for Lua source code. Here we test that the parser reports
+sensible syntax errors in specific cases.
+
+# Expressions
+
+## Invalid equals
+We correct the user if they type `=` instead of `==`.
+
+```lua
+if a = b then end
+```
+
+```txt
+Unexpected = in expression.
+   |
+ 1 | if a = b then end
+   |      ^
+Tip: Replace this with == to check if two values are equal.
+```
+
+We apply a slightly different error when this occurs in tables:
+
+```lua
+return { "abc" = "def" }
+```
+
+```txt
+Unexpected = in expression.
+   |
+ 1 | return { "abc" = "def" }
+   |                ^
+Tip: Wrap the preceding expression in [ and ] to use it as a table key.
+```
+
+Note this doesn't occur if this there's already a table key here:
+
+```lua
+return { x = "abc" = }
+```
+
+```txt
+Unexpected = in expression.
+   |
+ 1 | return { x = "abc" = }
+   |                    ^
+Tip: Replace this with == to check if two values are equal.
+```
+
+## Unclosed parenthesis
+We warn on unclosed parenthesis in expressions:
+
+```lua
+return (2
+```
+
+```txt
+Unexpected end of file. Are you missing a closing bracket?
+   |
+ 1 | return (2
+   |        ^ Brackets were opened here.
+   |
+ 1 | return (2
+   |          ^ Unexpected end of file here.
+```
+
+Function calls:
+
+```lua
+return f(2
+```
+
+```txt
+Unexpected end of file. Are you missing a closing bracket?
+   |
+ 1 | return f(2
+   |         ^ Brackets were opened here.
+   |
+ 1 | return f(2
+   |           ^ Unexpected end of file here.
+```
+
+and function definitions:
+
+```lua
+local function f(a
+```
+
+```txt
+Unexpected end of file. Are you missing a closing bracket?
+   |
+ 1 | local function f(a
+   |                 ^ Brackets were opened here.
+   |
+ 1 | local function f(a
+   |                   ^ Unexpected end of file here.
+```
+
+# Statements
+
+## Local functions with table identifiers
+We provide a custom error for using `.` inside a `local function` name.
+
+```lua
+local function x.f() end
+```
+
+```txt
+Cannot use local function with a table key.
+   |
+ 1 | local function x.f() end
+   |                 ^ . appears here.
+   |
+ 1 | local function x.f() end
+   | ^^^^^ Tip: Try removing this local keyword.
+```
+
+## Standalone identifiers
+A common error is a user forgetting to use `()` to call a function. We provide
+a custom error for this case:
+
+```lua
+term.clear
+local _ = 1
+```
+
+```txt
+Unexpected symbol after variable.
+   |
+ 1 | term.clear
+   |           ^ Expected something before the end of the line.
+Tip: Use () to call with no arguments.
+```
+
+If the next symbol is on the same line we provide a slightly different error:
+
+```lua
+x 1
+```
+
+```txt
+Unexpected symbol after name.
+   |
+ 1 | x 1
+   |   ^
+Did you mean to assign this or call it as a function?
+```
+
+An EOF token is treated as a new line.
+
+```lua
+term.clear
+```
+
+```txt
+Unexpected symbol after variable.
+   |
+ 1 | term.clear
+   |           ^ Expected something before the end of the line.
+Tip: Use () to call with no arguments.
+```
+
+## If statements
+For if statements, we say when we expected the `then` keyword.
+
+```lua
+if 0
+```
+
+```txt
+Expected then after if condition.
+   |
+ 1 | if 0
+   | ^^ If statement started here.
+   |
+ 1 | if 0
+   |     ^ Expected then before here.
+```
+
+```lua
+if 0 then
+elseif 0
+```
+
+```txt
+Expected then after if condition.
+   |
+ 2 | elseif 0
+   | ^^^^^^ If statement started here.
+   |
+ 2 | elseif 0
+   |         ^ Expected then before here.
+```
+
+## Expecting `end`
+We provide errors for missing `end`s.
+
+```lua
+if true then
+  print("Hello")
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | if true then
+   | ^^ Block started here.
+   |
+ 2 |   print("Hello")
+   |                 ^ Expected end of block here.
+```
+
+```lua
+if true then
+else
+  print("Hello")
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 2 | else
+   | ^^^^ Block started here.
+   |
+ 3 |   print("Hello")
+   |                 ^ Expected end of block here.
+```
+
+```lua
+if true then
+elseif true then
+  print("Hello")
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 2 | elseif true then
+   | ^^^^^^ Block started here.
+   |
+ 3 |   print("Hello")
+   |                 ^ Expected end of block here.
+```
+
+```lua
+while true do
+  print("Hello")
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | while true do
+   | ^^^^^ Block started here.
+   |
+ 2 |   print("Hello")
+   |                 ^ Expected end of block here.
+```
+
+```lua
+local function f()
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | local function f()
+   | ^^^^^^^^^^^^^^ Block started here.
+   |
+ 1 | local function f()
+   |                   ^ Expected end of block here.
+```
+
+```lua
+function f()
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | function f()
+   | ^^^^^^^^ Block started here.
+   |
+ 1 | function f()
+   |             ^ Expected end of block here.
+```
+
+```lua
+return function()
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | return function()
+   |        ^^^^^^^^ Block started here.
+   |
+ 1 | return function()
+   |                  ^ Expected end of block here.
+```
+
+While we typically see these errors at the end of the file, there are some cases
+where it may occur before then:
+
+```lua
+return (function()
+  if true then
+)()
+```
+
+```txt
+Unexpected ). Expected end or another statement.
+   |
+ 2 |   if true then
+   |   ^^ Block started here.
+   |
+ 3 | )()
+   | ^ Expected end of block here.
+```
+
+Note we do not currently attempt to identify mismatched `end`s. This might be
+something to do in the future.
+
+```lua
+if true then
+  while true do
+end
+```
+
+```txt
+Unexpected end of file. Expected end or another statement.
+   |
+ 1 | if true then
+   | ^^ Block started here.
+   |
+ 3 | end
+   |    ^ Expected end of block here.
+```
+
+## Unexpected `end`
+We also print when there's more `end`s than expected.
+
+```lua
+if true then
+end
+end
+```
+
+```txt
+Unexpected end.
+   |
+ 3 | end
+   | ^^^
+Your program contains more ends than needed. Check each block (if, for, function, ...) only has one end.
+```
+
+```lua
+repeat
+  if true then
+  end
+  end
+until true
+```
+
+```txt
+Unexpected end.
+   |
+ 4 |   end
+   |   ^^^
+Your program contains more ends than needed. Check each block (if, for, function, ...) only has one end.
+```

src/test/resources/test-rom/spec/modules/cc/internal/syntax/syntax_helpers.lua

@@ -0,0 +1,107 @@
+local expect = require "cc.expect".expect
+local lex_one = require "cc.internal.syntax.lexer".lex_one
+local parser = require "cc.internal.syntax.parser"
+local tokens, last_token = parser.tokens, parser.tokens.COMMENT
+
+--- Make a dummy context.
+local function make_context(input)
+    local lines = { 1 }
+    local function line(pos) lines[#lines + 1] = pos end
+
+    local function get_pos(pos)
+        for i = #lines, 1, -1 do
+            local start = lines[i]
+            if pos >= start then return i, pos - start + 1, start end
+        end
+
+        error("Position is <= 0", 2)
+    end
+
+    return { line = line, get_pos = get_pos, lines = lines }
+end
+
+--[[- Run a parser on an input string, capturing its output.
+
+This uses a simplified method of displaying errors (compared with
+@{cc.internal.error_printer}), which is suitable for printing to a file.
+
+@tparam string input The input string to parse.
+@tparam[opt=false] boolean print_tokens Whether to print each token as its parsed.
+@tparam[opt] number start The start state of the parser.
+@treturn string The parser's output
+]]
+local function capture_parser(input, print_tokens, start)
+    expect(1, input, "string")
+    expect(2, print_tokens, "boolean", "nil")
+    expect(3, start, "number", "nil")
+
+    local error_sentinel = {}
+    local out = {}
+    local function print(x) out[#out + 1] = tostring(x) end
+
+    local function get_name(token)
+        for name, tok in pairs(tokens) do if tok == token then return name end end
+        return "?[" .. tostring(token) .. "]"
+    end
+
+    local context = make_context(input)
+    function context.report(message)
+        expect(3, message, "table")
+
+        for _, msg in ipairs(message) do
+            if type(msg) == "table" and msg.tag == "annotate" then
+                local line, col = context.get_pos(msg.start_pos)
+                local end_line, end_col = context.get_pos(msg.end_pos)
+
+                local contents = input:match("^([^\r\n]*)", context.lines[line])
+                print("   |")
+                print(("%2d | %s"):format(line, contents))
+
+                local indicator = line == end_line and ("^"):rep(end_col - col + 1) or "^..."
+                if #msg.msg > 0 then
+                    print(("   | %s%s %s"):format((" "):rep(col - 1), indicator, msg.msg))
+                else
+                    print(("   | %s%s"):format((" "):rep(col - 1), indicator))
+                end
+            else
+                print(tostring(msg))
+            end
+        end
+    end
+
+    local pos = 1
+    local ok, err = xpcall(function()
+        return parser.parse(context, function()
+            while true do
+                local token, start, finish, content = lex_one(context, input, pos)
+                if not token then return tokens.EOF, #input + 1, #input + 1 end
+
+                if print_tokens then
+                    local start_line, start_col = context.get_pos(start)
+                    local end_line, end_col = context.get_pos(finish)
+                    local text = input:sub(start, finish)
+                    print(("%d:%d-%d:%d %s %s"):format(
+                        start_line, start_col, end_line, end_col,
+                        get_name(token), content or text:gsub("\n", "<NL>")
+                    ))
+                end
+
+                pos = finish + 1
+
+                if token < last_token then
+                    return token, start, finish
+                elseif token == tokens.ERROR then
+                    error(error_sentinel)
+                end
+            end
+        end, start)
+    end, debug.traceback)
+
+    if not ok and err ~= error_sentinel then
+        print(err)
+    end
+
+    return table.concat(out, "\n")
+end
+
+return { make_context = make_context, capture_parser = capture_parser }

src/test/resources/test-rom/spec/programs/advanced/bg_spec.lua

@@ -4,7 +4,7 @@ describe("The bg program", function()
     it("opens a tab in the background", function()
         local openTab = stub(shell, "openTab", function() return 12 end)
         local switchTab = stub(shell, "switchTab")
-        capture(stub, "bg")
+        capture("bg")
         expect(openTab):called_with("shell")
         expect(switchTab):called(0)
     end)

src/test/resources/test-rom/spec/programs/advanced/fg_spec.lua

@@ -4,7 +4,7 @@ describe("The fg program", function()
     it("opens the shell in the foreground", function()
         local openTab = stub(shell, "openTab", function() return 12 end)
         local switchTab = stub(shell, "switchTab")
-        capture(stub, "fg")
+        capture("fg")
         expect(openTab):called_with("shell")
         expect(switchTab):called_with(12)
     end)

src/test/resources/test-rom/spec/programs/alias_spec.lua

@@ -2,27 +2,27 @@ local capture = require "test_helpers".capture_program
 
 describe("The alias program", function()
     it("displays its usage when given too many arguments", function()
-        expect(capture(stub, "alias a b c"))
+        expect(capture("alias a b c"))
             :matches { ok = true, output = "Usage: alias <alias> <program>\n", error = "" }
     end)
 
     it("lists aliases", function()
         local pagedTabulate = stub(textutils, "pagedTabulate", function(x) print(table.unpack(x)) end)
         stub(shell, "aliases", function() return { cp = "copy" } end)
-        expect(capture(stub, "alias"))
+        expect(capture("alias"))
             :matches { ok = true, output = "cp:copy\n", error = "" }
         expect(pagedTabulate):called_with_matching({ "cp:copy" })
     end)
 
     it("sets an alias", function()
         local setAlias = stub(shell, "setAlias")
-        capture(stub, "alias test Hello")
+        capture("alias test Hello")
         expect(setAlias):called_with("test", "Hello")
     end)
 
     it("clears an alias", function()
         local clearAlias = stub(shell, "clearAlias")
-        capture(stub, "alias test")
+        capture("alias test")
         expect(clearAlias):called_with("test")
     end)
 end)

src/test/resources/test-rom/spec/programs/cd_spec.lua

@@ -3,17 +3,17 @@ local capture = require "test_helpers".capture_program
 describe("The cd program", function()
     it("changes into a directory", function()
         local setDir = stub(shell, "setDir")
-        capture(stub, "cd /rom/programs")
+        capture("cd /rom/programs")
         expect(setDir):called_with("rom/programs")
     end)
 
     it("does not move into a non-existent directory", function()
-        expect(capture(stub, "cd /rom/nothing"))
+        expect(capture("cd /rom/nothing"))
             :matches { ok = true, output = "Not a directory\n", error = "" }
     end)
 
     it("displays the usage when given no arguments", function()
-        expect(capture(stub, "cd"))
+        expect(capture("cd"))
             :matches { ok = true, output = "Usage: cd <path>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/clear_spec.lua

@@ -5,7 +5,7 @@ describe("The clear program", function()
         local clear = stub(term, "clear")
         local setCursorPos = stub(term, "setCursorPos")
 
-        capture(stub, "clear")
+        capture("clear")
 
         expect(clear):called(1)
         expect(setCursorPos):called_with(1, 1)

src/test/resources/test-rom/spec/programs/command/commands_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The commands program", function()
     it("displays an error without the commands api", function()
         stub(_G, "commands", nil)
-        expect(capture(stub, "/rom/programs/command/commands.lua"))
+        expect(capture("/rom/programs/command/commands.lua"))
             :matches { ok = true, output = "", error = "Requires a Command Computer.\n" }
     end)
 
@@ -13,7 +13,7 @@ describe("The commands program", function()
             list = function() return { "computercraft" } end,
         })
 
-        expect(capture(stub, "/rom/programs/command/commands.lua"))
+        expect(capture("/rom/programs/command/commands.lua"))
             :matches { ok = true, output = "Available commands:\ncomputercraft\n", error = "" }
         expect(pagedTabulate):called_with_matching({ "computercraft" })
     end)

src/test/resources/test-rom/spec/programs/command/exec_spec.lua

@@ -3,13 +3,13 @@ local capture = require "test_helpers".capture_program
 describe("The exec program", function()
     it("displays an error without the commands api", function()
         stub(_G, "commands", nil)
-        expect(capture(stub, "/rom/programs/command/exec.lua"))
+        expect(capture("/rom/programs/command/exec.lua"))
             :matches { ok = true, output = "", error = "Requires a Command Computer.\n" }
     end)
 
     it("displays its usage when given no argument", function()
         stub(_G, "commands", {})
-        expect(capture(stub, "/rom/programs/command/exec.lua"))
+        expect(capture("/rom/programs/command/exec.lua"))
             :matches { ok = true, output = "", error = "Usage: /rom/programs/command/exec.lua <command>\n" }
     end)
 
@@ -18,7 +18,7 @@ describe("The exec program", function()
             exec = function() return true, { "Hello World!" } end,
         })
 
-        expect(capture(stub, "/rom/programs/command/exec.lua computercraft"))
+        expect(capture("/rom/programs/command/exec.lua computercraft"))
             :matches { ok = true, output = "Success\nHello World!\n", error = "" }
     end)
 
@@ -27,7 +27,7 @@ describe("The exec program", function()
             exec = function() return false, { "Hello World!" } end,
         })
 
-        expect(capture(stub, "/rom/programs/command/exec.lua computercraft"))
+        expect(capture("/rom/programs/command/exec.lua computercraft"))
             :matches { ok = true, output = "Hello World!\n", error = "Failed\n" }
     end)
 end)

src/test/resources/test-rom/spec/programs/copy_spec.lua

@@ -15,26 +15,26 @@ describe("The copy program", function()
     end)
 
     it("fails when copying a non-existent file", function()
-        expect(capture(stub, "copy nothing destination"))
+        expect(capture("copy nothing destination"))
             :matches { ok = true, output = "", error = "No matching files\n" }
     end)
 
     it("fails when overwriting an existing file", function()
         touch("/test-files/copy/c.txt")
 
-        expect(capture(stub, "copy /test-files/copy/c.txt /test-files/copy/c.txt"))
+        expect(capture("copy /test-files/copy/c.txt /test-files/copy/c.txt"))
             :matches { ok = true, output = "", error = "Destination exists\n" }
     end)
 
     it("fails when copying into read-only locations", function()
         touch("/test-files/copy/d.txt")
 
-        expect(capture(stub, "copy /test-files/copy/d.txt /rom/test.txt"))
+        expect(capture("copy /test-files/copy/d.txt /rom/test.txt"))
             :matches { ok = true, output = "", error = "Destination is read-only\n" }
     end)
 
     it("displays the usage when given no arguments", function()
-        expect(capture(stub, "copy"))
+        expect(capture("copy"))
             :matches { ok = true, output = "Usage: copy <source> <destination>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/delete_spec.lua

@@ -36,17 +36,17 @@ describe("The rm program", function()
     end)
 
     it("displays the usage with no arguments", function()
-        expect(capture(stub, "rm"))
+        expect(capture("rm"))
             :matches { ok = true, output = "Usage: rm <paths>\n", error = "" }
     end)
 
     it("errors when trying to delete a read-only file", function()
-        expect(capture(stub, "rm /rom/startup.lua"))
+        expect(capture("rm /rom/startup.lua"))
             :matches { ok = true, output = "", error = "Cannot delete read-only file /rom/startup.lua\n" }
     end)
 
     it("errors when trying to delete the root mount", function()
-        expect(capture(stub, "rm /")):matches {
+        expect(capture("rm /")):matches {
             ok = true,
             output = "To delete its contents run rm /*\n",
             error = "Cannot delete mount /\n",
@@ -54,7 +54,7 @@ describe("The rm program", function()
     end)
 
     it("errors when a glob fails to match", function()
-        expect(capture(stub, "rm", "never-existed"))
+        expect(capture("rm", "never-existed"))
             :matches { ok = true, output = "", error = "never-existed: No matching files\n" }
     end)
 end)

src/test/resources/test-rom/spec/programs/drive_spec.lua

@@ -4,13 +4,13 @@ describe("The drive program", function()
     it("run the program", function()
         local getFreeSpace = stub(fs, "getFreeSpace", function() return 1234e4 end)
 
-        expect(capture(stub, "drive"))
+        expect(capture("drive"))
             :matches { ok = true, output = "hdd (12.3MB remaining)\n", error = "" }
         expect(getFreeSpace):called(1):called_with("")
     end)
 
     it("fails on a non-existent path", function()
-        expect(capture(stub, "drive /rom/nothing"))
+        expect(capture("drive /rom/nothing"))
             :matches { ok = true, output = "No such path\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/edit_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The edit program", function()
 
     it("displays its usage when given no argument", function()
-        expect(capture(stub, "edit"))
+        expect(capture("edit"))
             :matches { ok = true, output = "Usage: edit <path>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/eject_spec.lua

@@ -2,12 +2,12 @@ local capture = require "test_helpers".capture_program
 
 describe("The eject program", function()
     it("displays its usage when given no argument", function()
-        expect(capture(stub, "eject"))
+        expect(capture("eject"))
             :matches { ok = true, output = "Usage: eject <drive>\n", error = "" }
     end)
 
     it("fails when trying to eject a non-drive", function()
-        expect(capture(stub, "eject /rom"))
+        expect(capture("eject /rom"))
             :matches { ok = true, output = "Nothing in /rom drive\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/exit_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The exit program", function()
     it("exits the shell", function()
         local exit = stub(shell, "exit")
-        expect(capture(stub, "exit")):matches { ok = true, combined = "" }
+        expect(capture("exit")):matches { ok = true, combined = "" }
         expect(exit):called(1)
     end)
 end)

src/test/resources/test-rom/spec/programs/fun/advanced/paint_spec.lua

@@ -2,7 +2,7 @@ local capture = require "test_helpers".capture_program
 
 describe("The paint program", function()
     it("displays its usage when given no arguments", function()
-        expect(capture(stub, "paint"))
+        expect(capture("paint"))
             :matches { ok = true, output = "Usage: paint <path>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/fun/dj_spec.lua

@@ -2,12 +2,12 @@ local capture = require "test_helpers".capture_program
 
 describe("The dj program", function()
     it("displays its usage when given too many arguments", function()
-        expect(capture(stub, "dj a b c"))
+        expect(capture("dj a b c"))
             :matches { ok = true, output = "Usages:\ndj play\ndj play <drive>\ndj stop\n", error = "" }
     end)
 
     it("fails when no disks are present", function()
-        expect(capture(stub, "dj"))
+        expect(capture("dj"))
             :matches { ok = true, output = "No Music Discs in attached disk drives\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/fun/hello_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The hello program", function()
     it("says hello", function()
         local slowPrint = stub(textutils, "slowPrint", function(...) return print(...) end)
-        expect(capture(stub, "hello"))
+        expect(capture("hello"))
             :matches { ok = true, output = "Hello World!\n", error = "" }
         expect(slowPrint):called(1)
     end)

src/test/resources/test-rom/spec/programs/gps_spec.lua

@@ -2,21 +2,21 @@ local capture = require "test_helpers".capture_program
 
 describe("The gps program", function()
     it("displays its usage when given no arguments", function()
-        expect(capture(stub, "gps"))
+        expect(capture("gps"))
             :matches { ok = true, output = "Usages:\ngps host\ngps host <x> <y> <z>\ngps locate\n", error = "" }
     end)
 
     it("fails on a pocket computer", function()
         stub(_G, "pocket", {})
 
-        expect(capture(stub, "gps host"))
+        expect(capture("gps host"))
             :matches { ok = true, output = "GPS Hosts must be stationary\n", error = "" }
     end)
 
     it("can locate the computer", function()
         local locate = stub(gps, "locate", function() print("Some debugging information.") end)
 
-        expect(capture(stub, "gps locate"))
+        expect(capture("gps locate"))
             :matches { ok = true, output = "Some debugging information.\n", error = "" }
         expect(locate):called_with(2, true)
     end)

src/test/resources/test-rom/spec/programs/help_spec.lua

@@ -20,7 +20,7 @@ describe("The help program", function()
     end
 
     it("errors when there is no such help file", function()
-        expect(capture(stub, "help nothing"))
+        expect(capture("help nothing"))
             :matches { ok = true, error = "No help available\n", output = "" }
     end)
 

src/test/resources/test-rom/spec/programs/http/pastebin_spec.lua

@@ -34,7 +34,7 @@ describe("The pastebin program", function()
 
     it("downloads one file", function()
         setup_request()
-        capture(stub, "pastebin", "get", "abcde", "testdown")
+        capture("pastebin", "get", "abcde", "testdown")
 
         expect(fs.exists("/testdown")):eq(true)
     end)
@@ -42,7 +42,7 @@ describe("The pastebin program", function()
     it("runs a program from the internet", function()
         setup_request()
 
-        expect(capture(stub, "pastebin", "run", "abcde", "a", "b", "c"))
+        expect(capture("pastebin", "run", "abcde", "a", "b", "c"))
             :matches { ok = true, output = "Connecting to pastebin.com... Success.\nHello a b c\n", error = "" }
     end)
 
@@ -52,21 +52,21 @@ describe("The pastebin program", function()
         local file = fs.open("testup", "w")
         file.close()
 
-        expect(capture(stub, "pastebin", "put", "testup"))
+        expect(capture("pastebin", "put", "testup"))
             :matches { ok = true, output = "Connecting to pastebin.com... Success.\nUploaded as https://pastebin.com/abcde\nRun \"pastebin get abcde\" to download anywhere\n", error = "" }
     end)
 
     it("upload a not existing program to pastebin", function()
         setup_request()
 
-        expect(capture(stub, "pastebin", "put", "nothing"))
+        expect(capture("pastebin", "put", "nothing"))
             :matches { ok = true, output = "No such file\n", error = "" }
     end)
 
     it("displays its usage when given no arguments", function()
         setup_request()
 
-        expect(capture(stub, "pastebin"))
+        expect(capture("pastebin"))
             :matches { ok = true, output = "Usages:\npastebin put <filename>\npastebin get <code> <filename>\npastebin run <code> <arguments>\n", error = "" }
     end)
 

src/test/resources/test-rom/spec/programs/http/wget_spec.lua

@@ -23,7 +23,7 @@ describe("The wget program", function()
         fs.delete("/example.com")
         setup_request(default_contents)
 
-        capture(stub, "wget", "https://example.com")
+        capture("wget", "https://example.com")
 
         expect(fs.exists("/example.com")):eq(true)
     end)
@@ -32,7 +32,7 @@ describe("The wget program", function()
         fs.delete("/test-files/download")
         setup_request(default_contents)
 
-        capture(stub, "wget", "https://example.com /test-files/download")
+        capture("wget", "https://example.com /test-files/download")
 
         expect(fs.exists("/test-files/download")):eq(true)
     end)
@@ -41,7 +41,7 @@ describe("The wget program", function()
         fs.delete("/test-files/download")
         setup_request(nil)
 
-        capture(stub, "wget", "https://example.com", "/test-files/download")
+        capture("wget", "https://example.com", "/test-files/download")
 
         expect(fs.exists("/test-files/download")):eq(true)
         expect(fs.getSize("/test-files/download")):eq(0)
@@ -50,7 +50,7 @@ describe("The wget program", function()
     it("cannot save to rom", function()
         setup_request(default_contents)
 
-        expect(capture(stub, "wget", "https://example.com", "/rom/a-file.txt")):matches {
+        expect(capture("wget", "https://example.com", "/rom/a-file.txt")):matches {
             ok = true,
             output = "Connecting to https://example.com... Success.\n",
             error = "Cannot save file: /rom/a-file.txt: Access denied\n",
@@ -60,14 +60,14 @@ describe("The wget program", function()
     it("runs a program from the internet", function()
         setup_request(default_contents)
 
-        expect(capture(stub, "wget", "run", "http://test.com", "a", "b", "c"))
+        expect(capture("wget", "run", "http://test.com", "a", "b", "c"))
             :matches { ok = true, output = "Connecting to http://test.com... Success.\nHello a b c\n", error = "" }
     end)
 
     it("displays its usage when given no arguments", function()
         setup_request(default_contents)
 
-        expect(capture(stub, "wget"))
+        expect(capture("wget"))
             :matches { ok = true, output = "Usage:\nwget <url> [filename]\nwget run <url>\n", error = "" }
     end)
 

src/test/resources/test-rom/spec/programs/id_spec.lua

@@ -5,7 +5,7 @@ describe("The id program", function()
     it("displays computer id", function()
         local id = os.getComputerID()
 
-        expect(capture(stub, "id"))
+        expect(capture("id"))
             :matches { ok = true, output = "This is computer #" .. id .. "\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/import_spec.lua

@@ -0,0 +1,36 @@
+local with_window = require "test_helpers".with_window
+
+describe("The import program", function()
+    local function create_file(name, contents)
+        local did_read = false
+        return {
+            getName = function() return name end,
+            read = function()
+                if did_read then return end
+                did_read = true
+                return contents
+            end,
+            close = function() end,
+        }
+    end
+    local function create_files(files) return { getFiles = function() return files end } end
+
+    it("uploads files", function()
+        fs.delete("transfer.txt")
+
+        with_window(32, 5, function()
+            local queue = {
+                { "import" },
+                { "file_transfer", create_files { create_file("transfer.txt", "empty file") } },
+            }
+            local co = coroutine.create(shell.run)
+            for _, event in pairs(queue) do assert(coroutine.resume(co, table.unpack(event))) end
+        end)
+
+        local handle = fs.open("transfer.txt", "rb")
+        local contents = handle.readAll()
+        handle.close()
+
+        expect(contents):eq("empty file")
+    end)
+end)

src/test/resources/test-rom/spec/programs/label_spec.lua

@@ -2,33 +2,33 @@ local capture = require "test_helpers".capture_program
 
 describe("The label program", function()
     it("displays its usage when given no arguments", function()
-        expect(capture(stub, "label"))
+        expect(capture("label"))
             :matches { ok = true, output = "Usages:\nlabel get\nlabel get <drive>\nlabel set <text>\nlabel set <drive> <text>\nlabel clear\nlabel clear <drive>\n", error = "" }
     end)
 
     describe("displays the computer's label", function()
         it("when it is not labelled", function()
             stub(os, "getComputerLabel", function() return nil end)
-            expect(capture(stub, "label get"))
+            expect(capture("label get"))
                 :matches { ok = true, output = "No Computer label\n", error = "" }
         end)
 
         it("when it is labelled", function()
             stub(os, "getComputerLabel", function() return "Test" end)
-            expect(capture(stub, "label get"))
+            expect(capture("label get"))
                 :matches { ok = true, output = "Computer label is \"Test\"\n", error = "" }
         end)
     end)
 
     it("sets the computer's label", function()
         local setComputerLabel = stub(os, "setComputerLabel")
-        capture(stub, "label set Test")
+        capture("label set Test")
         expect(setComputerLabel):called_with("Test")
     end)
 
     it("clears the computer's label", function()
         local setComputerLabel = stub(os, "setComputerLabel")
-        capture(stub, "label clear")
+        capture("label clear")
         expect(setComputerLabel):called_with(nil)
     end)
 end)

src/test/resources/test-rom/spec/programs/list_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The list program", function()
     it("lists files", function()
         local pagedTabulate = stub(textutils, "pagedTabulate")
-        capture(stub, "list /rom")
+        capture("list /rom")
         expect(pagedTabulate):called_with_matching(
             colors.green, { "apis", "autorun", "help", "modules", "programs" },
             colors.white, { "motd.txt", "startup.lua" }
@@ -11,12 +11,12 @@ describe("The list program", function()
     end)
 
     it("fails on a non-existent directory", function()
-        expect(capture(stub, "list /rom/nothing"))
+        expect(capture("list /rom/nothing"))
             :matches { ok = true, output = "", error = "Not a directory\n" }
     end)
 
     it("fails on a file", function()
-        expect(capture(stub, "list /rom/startup.lua"))
+        expect(capture("list /rom/startup.lua"))
             :matches { ok = true, output = "", error = "Not a directory\n" }
     end)
 end)

src/test/resources/test-rom/spec/programs/monitor_spec.lua

@@ -2,7 +2,7 @@ local capture = require "test_helpers".capture_program
 
 describe("The monitor program", function()
     it("displays its usage when given no arguments", function()
-        expect(capture(stub, "monitor"))
+        expect(capture("monitor"))
             :matches {
                 ok = true,
                 output =
@@ -17,7 +17,7 @@ describe("The monitor program", function()
         local r = 1
         stub(peripheral, "call", function(s, f, t) r = t end)
         stub(peripheral, "getType", function() return "monitor" end)
-        expect(capture(stub, "monitor", "scale", "left", "0.5"))
+        expect(capture("monitor", "scale", "left", "0.5"))
             :matches { ok = true, output = "", error = "" }
         expect(r):equals(0.5)
     end)
@@ -26,7 +26,7 @@ describe("The monitor program", function()
         local r = 1
         stub(peripheral, "call", function(s, f, t) r = t end)
         stub(peripheral, "getType", function(side) return side == "left" and "monitor" or nil end)
-        expect(capture(stub, "monitor", "scale", "left"))
+        expect(capture("monitor", "scale", "left"))
             :matches {
                 ok = true,
                 output =
@@ -35,9 +35,9 @@ describe("The monitor program", function()
                     "  monitor scale <name> <scale>\n",
                 error = "",
             }
-        expect(capture(stub, "monitor", "scale", "top", "0.5"))
+        expect(capture("monitor", "scale", "top", "0.5"))
             :matches { ok = true, output = "No monitor named top\n", error = "" }
-        expect(capture(stub, "monitor", "scale", "left", "aaa"))
+        expect(capture("monitor", "scale", "left", "aaa"))
             :matches { ok = true, output = "Invalid scale: aaa\n", error = "" }
         expect(r):equals(1)
     end)

src/test/resources/test-rom/spec/programs/motd_spec.lua

@@ -12,31 +12,31 @@ describe("The motd program", function()
         file.close()
         settings.set("motd.path", "/motd_check.txt")
 
-        expect(capture(stub, "motd"))
+        expect(capture("motd"))
             :matches { ok = true, output = "Hello World!\n", error = "" }
     end)
 
     it("displays date-specific MOTD (1 Jan)", function()
         setup_date(1, 1)
-        expect(capture(stub, "motd"))
+        expect(capture("motd"))
             :matches { ok = true, output = "Happy new year!\n", error = "" }
     end)
 
     it("displays date-specific MOTD (28 Apr)", function()
         setup_date(28, 4)
-        expect(capture(stub, "motd"))
+        expect(capture("motd"))
             :matches { ok = true, output = "Ed Balls\n", error = "" }
     end)
 
     it("displays date-specific MOTD (31 Oct)", function()
         setup_date(31, 10)
-        expect(capture(stub, "motd"))
+        expect(capture("motd"))
             :matches { ok = true, output = "OOoooOOOoooo! Spooky!\n", error = "" }
     end)
 
     it("displays date-specific MOTD (24 Dec)", function()
         setup_date(24, 12)
-        expect(capture(stub, "motd"))
+        expect(capture("motd"))
             :matches { ok = true, output = "Merry X-mas!\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/move_spec.lua

@@ -21,7 +21,7 @@ describe("The move program", function()
         touch("/test-files/move/a.txt")
         fs.makeDir("/test-files/move/a")
 
-        expect(capture(stub, "move /test-files/move/a.txt /test-files/move/a"))
+        expect(capture("move /test-files/move/a.txt /test-files/move/a"))
             :matches { ok = true }
 
         expect(fs.exists("/test-files/move/a.txt")):eq(false)
@@ -29,7 +29,7 @@ describe("The move program", function()
     end)
 
     it("fails when moving a file which doesn't exist", function()
-        expect(capture(stub, "move nothing destination"))
+        expect(capture("move nothing destination"))
             :matches { ok = true, output = "", error = "No matching files\n" }
     end)
 
@@ -37,7 +37,7 @@ describe("The move program", function()
         cleanup()
         touch("/test-files/move/a.txt")
 
-        expect(capture(stub, "move /test-files/move/a.txt /test-files/move/a.txt"))
+        expect(capture("move /test-files/move/a.txt /test-files/move/a.txt"))
             :matches { ok = true, output = "", error = "Destination exists\n" }
     end)
 
@@ -45,17 +45,17 @@ describe("The move program", function()
         cleanup()
         touch("/test-files/move/a.txt")
 
-        expect(capture(stub, "move /test-files/move/a.txt /rom/test.txt"))
+        expect(capture("move /test-files/move/a.txt /rom/test.txt"))
             :matches { ok = true, output = "", error = "Destination is read-only\n" }
     end)
 
     it("fails when moving from read-only locations", function()
-        expect(capture(stub, "move /rom/startup.lua /test-files/move/not-exist.txt"))
+        expect(capture("move /rom/startup.lua /test-files/move/not-exist.txt"))
             :matches { ok = true, output = "", error = "Cannot move read-only file /rom/startup.lua\n" }
     end)
 
     it("fails when moving mounts", function()
-        expect(capture(stub, "move /rom /test-files/move/rom"))
+        expect(capture("move /rom /test-files/move/rom"))
             :matches { ok = true, output = "", error = "Cannot move mount /rom\n" }
     end)
 
@@ -63,12 +63,12 @@ describe("The move program", function()
         cleanup()
         touch("/test-files/move/a.txt")
         touch("/test-files/move/b.txt")
-        expect(capture(stub, "move /test-files/move/*.txt /test-files/move/c.txt"))
+        expect(capture("move /test-files/move/*.txt /test-files/move/c.txt"))
             :matches { ok = true, output = "", error = "Cannot overwrite file multiple times\n" }
     end)
 
     it("displays the usage with no arguments", function()
-        expect(capture(stub, "move"))
+        expect(capture("move"))
             :matches { ok = true, output = "Usage: move <source> <destination>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/peripherals_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The peripherals program", function()
     it("says when there are no peripherals", function()
         stub(peripheral, 'getNames', function() return {} end)
-        expect(capture(stub, "peripherals"))
+        expect(capture("peripherals"))
             :matches { ok = true, output = "Attached Peripherals:\nNone\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/pocket/equip_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The pocket equip program", function()
     it("errors when not a pocket computer", function()
         stub(_G, "pocket", nil)
-        expect(capture(stub, "/rom/programs/pocket/equip.lua"))
+        expect(capture("/rom/programs/pocket/equip.lua"))
             :matches { ok = true, output = "", error = "Requires a Pocket Computer\n" }
     end)
 
@@ -12,7 +12,7 @@ describe("The pocket equip program", function()
             equipBack = function() return true end,
         })
 
-        expect(capture(stub, "/rom/programs/pocket/equip.lua"))
+        expect(capture("/rom/programs/pocket/equip.lua"))
             :matches { ok = true, output = "Item equipped\n", error = "" }
     end)
 
@@ -21,7 +21,7 @@ describe("The pocket equip program", function()
             equipBack = function() return false, "Cannot equip this item." end,
         })
 
-        expect(capture(stub, "/rom/programs/pocket/equip.lua"))
+        expect(capture("/rom/programs/pocket/equip.lua"))
             :matches { ok = true, output = "", error = "Cannot equip this item.\n" }
     end)
 end)

src/test/resources/test-rom/spec/programs/pocket/unequip_spec.lua

@@ -3,7 +3,7 @@ local capture = require "test_helpers".capture_program
 describe("The pocket unequip program", function()
     it("errors when not a pocket computer", function()
         stub(_G, "pocket", nil)
-        expect(capture(stub, "/rom/programs/pocket/unequip.lua"))
+        expect(capture("/rom/programs/pocket/unequip.lua"))
             :matches { ok = true, output = "", error = "Requires a Pocket Computer\n" }
     end)
 
@@ -12,7 +12,7 @@ describe("The pocket unequip program", function()
             unequipBack = function() return true end,
         })
 
-        expect(capture(stub, "/rom/programs/pocket/unequip.lua"))
+        expect(capture("/rom/programs/pocket/unequip.lua"))
             :matches { ok = true, output = "Item unequipped\n", error = "" }
     end)
 
@@ -21,7 +21,7 @@ describe("The pocket unequip program", function()
             unequipBack = function() return false, "Nothing to remove." end,
         })
 
-        expect(capture(stub, "/rom/programs/pocket/unequip.lua"))
+        expect(capture("/rom/programs/pocket/unequip.lua"))
             :matches { ok = true, output = "", error = "Nothing to remove.\n" }
     end)
 end)

src/test/resources/test-rom/spec/programs/programs_spec.lua

@@ -5,7 +5,7 @@ describe("The programs program", function()
         local programs = stub(shell, "programs", function() return { "some", "programs" } end)
         local pagedTabulate = stub(textutils, "pagedTabulate", function(x) print(table.unpack(x)) end)
 
-        expect(capture(stub, "/rom/programs/programs.lua"))
+        expect(capture("/rom/programs/programs.lua"))
             :matches { ok = true, output = "some programs\n", error = "" }
 
         expect(programs):called_with(false)

src/test/resources/test-rom/spec/programs/reboot_spec.lua

@@ -5,7 +5,7 @@ describe("The reboot program", function()
         local sleep = stub(_G, "sleep")
         local reboot = stub(os, "reboot")
 
-        expect(capture(stub, "reboot"))
+        expect(capture("reboot"))
             :matches { ok = true, output = "Goodbye\n", error = "" }
 
         expect(sleep):called_with(1)

src/test/resources/test-rom/spec/programs/redstone_spec.lua

@@ -2,7 +2,7 @@ local capture = require "test_helpers".capture_program
 
 describe("The redstone program", function()
     it("displays its usage when given no arguments", function()
-        expect(capture(stub, "redstone"))
+        expect(capture("redstone"))
             :matches { ok = true, output = "Usages:\nredstone probe\nredstone set <side> <value>\nredstone set <side> <color> <value>\nredstone pulse <side> <count> <period>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/rename_spec.lua

@@ -15,36 +15,36 @@ describe("The rename program", function()
     end)
 
     it("fails when renaming a file which doesn't exist", function()
-        expect(capture(stub, "rename nothing destination"))
+        expect(capture("rename nothing destination"))
             :matches { ok = true, output = "", error = "No matching files\n" }
     end)
 
     it("fails when overwriting an existing file", function()
         touch("/test-files/rename/c.txt")
 
-        expect(capture(stub, "rename /test-files/rename/c.txt /test-files/rename/c.txt"))
+        expect(capture("rename /test-files/rename/c.txt /test-files/rename/c.txt"))
             :matches { ok = true, output = "", error = "Destination exists\n" }
     end)
 
     it("fails when renaming to read-only locations", function()
         touch("/test-files/rename/d.txt")
 
-        expect(capture(stub, "rename /test-files/rename/d.txt /rom/test.txt"))
+        expect(capture("rename /test-files/rename/d.txt /rom/test.txt"))
             :matches { ok = true, output = "", error = "Destination is read-only\n" }
     end)
 
     it("fails when renaming from read-only locations", function()
-        expect(capture(stub, "rename /rom/startup.lua /test-files/rename/d.txt"))
+        expect(capture("rename /rom/startup.lua /test-files/rename/d.txt"))
             :matches { ok = true, output = "", error = "Source is read-only\n" }
     end)
 
     it("fails when renaming mounts", function()
-        expect(capture(stub, "rename /rom /test-files/rename/rom"))
+        expect(capture("rename /rom /test-files/rename/rom"))
             :matches { ok = true, output = "", error = "Can't rename mounts\n" }
     end)
 
     it("displays the usage when given no arguments", function()
-        expect(capture(stub, "rename"))
+        expect(capture("rename"))
             :matches { ok = true, output = "Usage: rename <source> <destination>\n", error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/set_spec.lua

@@ -13,21 +13,21 @@ describe("The set program", function()
     it("displays all settings", function()
         setup()
 
-        expect(capture(stub, "set"))
+        expect(capture("set"))
             :matches { ok = true, output = '"test" is "Hello World!"\n"test.defined" is 456\n', error = "" }
     end)
 
     it("displays a single setting", function()
         setup()
 
-        expect(capture(stub, "set test"))
+        expect(capture("set test"))
             :matches { ok = true, output = 'test is "Hello World!"\n', error = "" }
     end)
 
     it("displays a single setting with description", function()
         setup()
 
-        expect(capture(stub, "set test"))
+        expect(capture("set test"))
             :matches { ok = true, output = 'test is "Hello World!"\n', error = "" }
     end)
 
@@ -35,14 +35,14 @@ describe("The set program", function()
         setup()
 
         settings.set("test.defined", 123)
-        expect(capture(stub, "set test.defined"))
+        expect(capture("set test.defined"))
             :matches { ok = true, output = 'test.defined is 123 (default is 456)\nA description\n', error = "" }
     end)
 
     it("set a setting", function()
         setup()
 
-        expect(capture(stub, "set test Hello"))
+        expect(capture("set test Hello"))
             :matches { ok = true, output = '"test" set to "Hello"\n', error = "" }
 
         expect(settings.get("test")):eq("Hello")
@@ -51,9 +51,9 @@ describe("The set program", function()
     it("checks the type of a setting", function()
         setup()
 
-        expect(capture(stub, "set test.defined Hello"))
+        expect(capture("set test.defined Hello"))
             :matches { ok = true, output = "", error = '"Hello" is not a valid number.\n' }
-        expect(capture(stub, "set test.defined 456"))
+        expect(capture("set test.defined 456"))
             :matches { ok = true, output = '"test.defined" set to 456\n', error = "" }
     end)
 end)

src/test/resources/test-rom/spec/programs/shell_spec.lua

@@ -120,7 +120,7 @@ describe("The shell", function()
         local function create_files(files) return { getFiles = function() return files end } end
 
         it("suspends the read prompt", function()
-            fs.delete("tmp.txt")
+            fs.delete("transfer.txt")
 
             local win = with_window(32, 5, function()
                 local queue = {

src/test/resources/test-rom/spec/programs/shutdown_spec.lua

@@ -6,7 +6,7 @@ describe("The shutdown program", function()
         local sleep = stub(_G, "sleep")
         local shutdown = stub(os, "shutdown")
 
-        expect(capture(stub, "shutdown"))
+        expect(capture("shutdown"))
             :matches { ok = true, output = "Goodbye\n", error = "" }
 
         expect(sleep):called_with(1)