uk.ac.ed.inf.ace.cli.OutStream.java Source code

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Here is the source code for uk.ac.ed.inf.ace.cli.OutStream.java

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/*
 * Copyright 2012 Daniel Renshaw <d.renshaw@sms.ed.ac.uk>.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package uk.ac.ed.inf.ace.cli;

import com.google.common.base.Strings;
import java.io.IOException;
import java.io.PrintStream;

/**
 * @author "Daniel Renshaw" <d.renshaw@sms.ed.ac.uk>
 */
public class OutStream extends PrintStream {

    private final PrintStream realOut;
    private String prompt = "";
    private boolean proxyEnabled = true;

    public OutStream(PrintStream out) {
        super(out);
        this.realOut = out;
    }

    private void undoInput() {
        if (proxyEnabled) {
            proxyEnabled = false;
            realOut.print(Strings.repeat("\b", prompt.length()));
        }
    }

    private void redoInput() {
        if (!proxyEnabled) {
            realOut.print(prompt);
            proxyEnabled = true;
        }
    }

    @Override
    public synchronized void write(int b) {
        undoInput();
        super.write(b);
        redoInput();
    }

    @Override
    public synchronized void write(byte[] buf, int off, int len) {
        undoInput();
        super.write(buf, off, len);
        redoInput();
    }

    @Override
    public synchronized void write(byte[] b) throws IOException {
        undoInput();
        super.write(b);
        redoInput();
    }

    public synchronized void printPrompt(String value) {
        prompt = value;
        realOut.print(prompt);
    }
}