/* File: CommandLoop.java
 * Contains: A class for interactive command-loops
 * Author: Jeff Dalton <J.Dalton@ed.ac.uk>
 * Created: February 1998
 * Updated: Sat Sep  2 18:50:58 2000 by Jeff Dalton
 * Copyright: (c) 1998, AIAI, University of Edinburgh
 */

package ix.util;

import java.util.*;
import java.io.*;
import ix.util.match.*;


/**
 *
 */

public class CommandLoop implements Runnable {

    MatchTable commandTable;
    String prompt = "Command:";
    String exit = "bye";

    BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

    PrintStream out = System.out;

    public CommandLoop(MatchTable commandTable) {
	this.commandTable = commandTable;
    }

    public CommandLoop(final Function1 eval) {
	this.commandTable = new MatchTable();
	commandTable.addCase(new MatchCase() {
	    public Object tryMatch(Object data) {
		return data;	// always match (unless data == null)
	    }
	    public Object ifSelected(Object data, Object matchResult) {
		return eval.funcall(data);
	    }
	});
    }

    public void setPrompt(String prompt) {
	this.prompt = prompt;
    }

    public void setExitCommand(String exit) {
	this.exit = exit;
    }

    public void run() {
	out.println("Type \"" + exit + "\" to exit.\n");
	for (;;) {
	    try {
		String command = ask(prompt);
		if (command.equals(exit))
		    break;
		out.println(commandTable.match(command));
		out.println("");
	    }
	    catch (Exception e) {
		Debug.noteException(e);
	    }
	}
	System.out.println("\nBye!\n");
    }

    protected String ask(String prompt) throws IOException {
	out.print(prompt + " ");
	out.flush();
	return in.readLine();
    }


}