Error when missing computers after executing the command

This allows you to automate running various commands and still have them
"work" if some computers are not loaded.

Closes #47

src/main/java/dan200/computercraft/shared/command/CommandComputerCraft.java

@@ -23,6 +23,7 @@ import net.minecraft.world.World;
 
 import javax.annotation.Nonnull;
 import java.util.*;
+import java.util.function.Consumer;
 
 import static dan200.computercraft.shared.command.framework.ChatHelpers.*;
 
@@ -147,19 +148,7 @@ public final class CommandComputerCraft extends CommandDelegate
             @Override
             public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
             {
-                Set<ServerComputer> computers = Sets.newHashSet();
+                withComputers( arguments, computers -> {
-                if( arguments.size() > 0 )
-                {
-                    for( String arg : arguments )
-                    {
-                        computers.addAll( ComputerSelector.getComputers( arg ) );
-                    }
-                }
-                else
-                {
-                    computers.addAll( ComputerCraft.serverComputerRegistry.getComputers() );
-                }
-
                     int shutdown = 0;
                     for( ServerComputer computer : computers )
                     {
@@ -167,6 +156,7 @@ public final class CommandComputerCraft extends CommandDelegate
                         computer.unload();
                     }
                     context.getSender().sendMessage( text( "Shutdown " + shutdown + " / " + computers.size() + " computers" ) );
+                } );
             }
 
             @Nonnull
@@ -188,19 +178,7 @@ public final class CommandComputerCraft extends CommandDelegate
             @Override
             public void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException
             {
-                Set<ServerComputer> computers = Sets.newHashSet();
+                withComputers( arguments, computers -> {
-                if( arguments.size() > 0 )
-                {
-                    for( String arg : arguments )
-                    {
-                        computers.addAll( ComputerSelector.getComputers( arg ) );
-                    }
-                }
-                else
-                {
-                    computers.addAll( ComputerCraft.serverComputerRegistry.getComputers() );
-                }
-
                     int on = 0;
                     for( ServerComputer computer : computers )
                     {
@@ -208,6 +186,7 @@ public final class CommandComputerCraft extends CommandDelegate
                         computer.turnOn();
                     }
                     context.getSender().sendMessage( text( "Turned on " + on + " / " + computers.size() + " computers" ) );
+                } );
             }
 
             @Nonnull
@@ -489,8 +468,6 @@ public final class CommandComputerCraft extends CommandDelegate
             if( server.getID() > maxId ) maxId = server.getID();
         }
 
-        ICommandSender sender = context.getSender();
-
         timings.sort( Comparator.<ComputerTracker, Long>comparing( x -> x.get( field ) ).reversed() );
 
         boolean defaultLayout = field == TrackingField.TASKS || field == TrackingField.TOTAL_TIME
@@ -526,4 +503,30 @@ public final class CommandComputerCraft extends CommandDelegate
 
         table.displayTo( context.getSender() );
     }
+
+    private static void withComputers( List<String> selectors, Consumer<Collection<ServerComputer>> action ) throws CommandException
+    {
+        Set<ServerComputer> computers = Sets.newHashSet();
+        List<String> failed = new ArrayList<>();
+        if( selectors.isEmpty() )
+        {
+            computers.addAll( ComputerCraft.serverComputerRegistry.getComputers() );
+        }
+        else
+        {
+            for( String selector : selectors )
+            {
+                List<ServerComputer> selected = ComputerSelector.getComputers( selector );
+                computers.addAll( selected );
+                if( selected.isEmpty() ) failed.add( selector );
+            }
+        }
+
+        action.accept( computers );
+
+        if( !failed.isEmpty() )
+        {
+            throw new CommandException( "Could not find computers matching " + String.join( ", ", failed ) );
+        }
+    }
 }

src/main/java/dan200/computercraft/shared/command/ComputerSelector.java

@@ -12,30 +12,22 @@ import java.util.function.Predicate;
 
 public final class ComputerSelector
 {
-    private static List<ServerComputer> getComputers( Predicate<ServerComputer> predicate, String selector ) throws CommandException
+    private static List<ServerComputer> getComputers( Predicate<ServerComputer> predicate ) throws CommandException
     {
         // We copy it to prevent concurrent modifications.
-        List<ServerComputer> computers = Lists.newArrayList( ComputerCraft.serverComputerRegistry.getComputers() );
+        ArrayList<ServerComputer> computers = new ArrayList<>( ComputerCraft.serverComputerRegistry.getComputers() );
-        List<ServerComputer> candidates = Lists.newArrayList();
+        computers.removeIf( predicate.negate() );
-        for( ServerComputer searchComputer : computers )
+        return computers;
-        {
-            if( predicate.test( searchComputer ) ) candidates.add( searchComputer );
-        }
-
-        if( candidates.isEmpty() )
-        {
-            throw new CommandException( "No computer matching " + selector );
-        }
-        else
-        {
-            return candidates;
-        }
     }
 
     public static ServerComputer getComputer( String selector ) throws CommandException
     {
         List<ServerComputer> computers = getComputers( selector );
-        if( computers.size() == 1 )
+        if( computers.size() == 0 )
+        {
+            throw new CommandException( "No computer matching " + selector );
+        }
+        else if( computers.size() == 1 )
         {
             return computers.get( 0 );
         }
@@ -71,17 +63,17 @@ public final class ComputerSelector
                 throw new CommandException( "'" + selector + "' is not a valid number" );
             }
 
-            return getComputers( x -> x.getID() == id, selector );
+            return getComputers( x -> x.getID() == id );
         }
         else if( selector.length() > 0 && selector.charAt( 0 ) == '@' )
         {
             String label = selector.substring( 1 );
-            return getComputers( x -> Objects.equals( label, x.getLabel() ), selector );
+            return getComputers( x -> Objects.equals( label, x.getLabel() ) );
         }
         else if( selector.length() > 0 && selector.charAt( 0 ) == '~' )
         {
             String familyName = selector.substring( 1 );
-            return getComputers( x -> x.getFamily().name().equalsIgnoreCase( familyName ), selector );
+            return getComputers( x -> x.getFamily().name().equalsIgnoreCase( familyName ) );
         }
         else
         {
@@ -96,14 +88,7 @@ public final class ComputerSelector
             }
 
             ServerComputer computer = ComputerCraft.serverComputerRegistry.get( instance );
-            if( computer == null )
+            return computer == null ? Collections.emptyList() : Collections.singletonList( computer );
-            {
-                throw new CommandException( "No such computer for instance id " + instance );
-            }
-            else
-            {
-                return Collections.singletonList( computer );
-            }
         }
     }