Completion

Æsh provide two different ways of doing completions depending on which API you're using. First we will cover the completion API provided when using AeshConsole and then the more low level API when using Console.

AeshConsole

When using AeshConsole the completion is specified for each Option thats defined in a Command. Here is an example of a simple command: 
@CommandDefinition(name="color", description = "set a color")
public static class ColorCommand implements Command {
    @Option
    private Color color;

    @Override
    public CommandResult execute(AeshConsole console) throws IOException {
        if(files != null) {
          for(File f : files)
            console.out().print(f.toString());
        }
        return CommandResult.SUCCESS;
    }
}
This command is supposed to let the user select

Console

For Console Æsh provide a simple API to connect commands to its tab-completion list. The only thing thats needed is to implement the Completion interface and attach it to Console with the method addCompletion(Completion) or addCompletions(List completionList) A simple Example: 
import org.jboss.aesh.complete.*;
import org.jboss.aesh.console.*;

public class Example {
  public static void main(String[] args) throws java.io.IOException {
    Console console = new Console(new SettingsBuilder().create());

    Completion completer = new Completion() {
      @Override
      public void complete(CompleteOperation co) {
        // very simple completor
        // if <tab> is pressed when the buffer is 'fo' or 'foo' it will
        // be completed to 'foobar'
        if(co.getBuffer().equals("fo") || co.getBuffer().equals("foo"))
          co.addCompletionCandidate("foobar");
      }
    };
    console.addCompletion(completer);

    final ConsoleCallback consoleCallback = new ConsoleCallback() {
      @Override
      public int readConsoleOutput(ConsoleOperation operation) throws IOException {
        console.out().println("======>\"" + operation.getBuffer());
        if (operation.getBuffer().equalsIgnoreCase("quit") || 
            operation.getBuffer().equalsIgnoreCase("exit") || 
            operation.getBuffer().equalsIgnoreCase("reset")) {
          console.stop();
        }
      }
    };
    console.setConsoleCallback(consoleCallback);
    console.start();
  }
}

CompleteOperation

The object that is sent with every registered Completion object is CompletionOperation :
  • buffer: is the current line when the user pressed 'tab'
  • cursor: the position of the cursor
  • completionCandidates: added by the programmer if the buffer match this completion.
  • offset: set by the programmer if Æsh should 'chop off' some of the completionCandidate when doing completion. Set it to the same value as cursor to keep the buffer unchanged.
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