Update ed.lua

Added some commands:
p - print line from buffer
"," - modify commands to use whole buffer
"w" - write buffer to file path

Added read/write to and from files (no input mode yet)
Added invoking of "!" shell evaluation (but no shell evaluation logic... until later)
Added hacky bullshit code for determining file path validity
Spite of GNU ed rising steadily

ed.lua

@@ -1,15 +1,16 @@
 -- ed text editor
 -- Port to ComputerCraft by LDDestroier
--- wget https://raw.githubusercontent.com/LDDestroier/CC/master/ed.lua
 
 local state = {
     output = 0,
     halt = false,
-    debug = true,
+    debug = false,
 
     mode = "command", -- command or input
 
     buffer = {},
+    line = 1,
+    filepath = nil,
 
     show_help = false,
     show_version = false,
@@ -275,6 +276,8 @@ state.strip_trailing_cr = t_options_list.strip_trailing_cr.value or state.strip_
 state.show_help         = t_options_list.help.value and (t_options_list.help.order < t_options_list.version.order)
 state.show_version      = t_options_list.version.value and (t_options_list.version.order < t_options_list.help.order)
 
+state.filepath = shell.resolve(n_args[1])
+
 if state.halt then
     return state.output
 end
@@ -388,30 +391,166 @@ local function fn_input()
     return text, interrupt
 end
 
+local function fn_check_valid_path(path, ignore_nonexist)
+    local good, err = true, ""
+
+    if not path then
+        good, err = false, ""
+    
+    elseif not fs.exists(path) then
+        good, err = false, "No such file or directory"
+        if ignore_nonexist then
+            good = true
+        end
+
+    elseif fs.isDir(path) then
+        good, err = false, "Is a directory"
+
+    end
+
+    return good, err
+end
+
+local function fn_file_read(path)
+    -- reads file and puts each line in a table
+
+    local valid = true
+    local err = ""
+
+    if not path then
+        return {}, false, "", 0
+    else
+        valid, err = fn_check_valid_path(path)
+        if not valid then
+            return {}, false, err, 0
+        end
+    end
+
+    local output = {}
+    local size = fs.getSize(path)
+    local file = fs.open(path, "r")
+    local line
+    repeat
+        line = file.readLine()
+        if line then
+            output[#output + 1] = line
+        end
+    until not line
+
+    return output, true, err, size
+end
+
+local function fn_file_write(path, buffer)
+    if not fn_check_valid_path(path, true) then
+        return false
+    end
+
+    local file = fs.open(path, "w")
+    for i = 1, #buffer do
+        file.write(buffer[i])
+        if i < #buffer then
+            file.write("\n")
+        end
+    end
+    file.close()
+
+    return fs.getSize(path)
+end
+
 local function fn_shell_resolve(command)
     -- TODO: make dynamically resizing window object
     -- set every pixel of window to black-on-black, then always make window draw white-on-white text to mark written regions
     -- then, return a table of lines from the window that are just as long as needed to represent the "marked" portions
+    -- ... or, I could figure out how to use lua's stdout functionality
     return {}
 end
 
 local function fn_command_parse(text)
     local valid = false
+    text = text:sub(text:find("[^%s]") or 0, -1) -- strip leading spaces
+    local command = text:match("^[^%s]+") or "" -- first word
+    local argument = text:sub(text:find("[^%s]", #command + 1) or (#text + 1), -1) -- rest of sentence
 
-    if text == "P" then
+    local whole = false
+    local program_output
+
+    -- TODO: add every command and every subcommand
+    -- TODO: implement Regex somehow (or settle on Lua patterns)
+
+    if #command == 0 then
+        if state.line < #state.buffer then
+            state.line = state.line + 1
+            valid = true
+            print(state.buffer[state.line])
+        end
+    end
+
+    if command:sub(1, 1) == "!" then -- shell evaluate
+        program_output = fn_shell_resolve(command:sub(2))
+        for i = 1, #program_output do
+            print(program_output[i])
+        end
+
+    elseif command:sub(1, 1) == "," then
+        whole = true
+        command = command:match("[^,]+.*")
+    end
+
+    if tonumber(command) then -- set edit line number
+        if state.buffer[tonumber(command)] then
+            state.line = tonumber(command)
+            print(state.buffer[state.line])
+            valid = true
+        end
+    end
+
+    if command == "p" then -- print
+        if whole then
+            for i = 1, #state.buffer do
+                print(state.buffer[i])
+            end
+            state.line = #state.buffer
+        else
+            print(state.buffer[state.line])
+        end
+        valid = true
+    end
+
+    if command == "w" then -- write to file
+        local p_valid, err
+
+        if #argument > 0 then
+            state.filepath = shell.resolve(argument)
+        end
+
+        if state.filepath then
+            p_valid, err = fn_check_valid_path(state.filepath, true)
+            if p_valid then
+                if fs.isReadOnly(state.filepath) then
+                    print(state.filepath .. ": Permission denied")
+                else
+                    print(fn_file_write(state.filepath, state.buffer)) -- print size of written
+                    valid = true
+                end
+            else
+                print(state.filepath .. ": " .. err)
+            end
+        end
+    end
+
+    if command == "P" then -- toggle prompt
         valid = true
         state.show_prompt = not state.show_prompt
     end
-    if text == "q" then
+    if command == "q" then -- get the fuck outta heeereeeee
         valid = true
         return false
     end
-    if text == "i" then
+    if command == "i" then -- enter input mode
         valid = true
         state.mode = "input"
     end
-
-    -- TODO: inplement every command
+    
 
     if not valid then
         print("?")
@@ -422,7 +561,7 @@ end
 
 local function fn_input_parse(text, interrupt)
     if interrupt then
-        state.mode == "command"
+        state.mode = "command"
         return true
     else
         print("WIP")
@@ -434,6 +573,23 @@ local function main()
     state.mode = "command"
     local running = true
     local text, interrupt
+
+    if state.filepath then
+        local valid, err, size
+        state.buffer, valid, err, size = fn_file_read(state.filepath)
+        if valid then
+            if state.filepath then
+                print(size)
+            end
+        else
+            print(state.filepath .. ": " .. err)
+            if fs.isDir(state.filepath) then
+                print("?") -- ed does it, I do it
+            end
+            state.filepath = nil
+        end
+    end
+
     while running do
         text, interrupt = fn_input()
         if interrupt then
@@ -452,8 +608,9 @@ local function main()
 
         end
     end
+
+    return state.output
+
 end
 
-main()
-
-return state.output
+return main()