/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 groovy.ui;
import groovy.lang.Closure;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.PrintStream;
/**
* Intercepts System.out/System.err. Implementation helper for Console.groovy.
*
* @version $Id$
*/
public class SystemOutputInterceptor extends FilterOutputStream {
private Closure callback;
private boolean output;
/**
* Constructor
*
* @param callback accepts a string to be sent to std out and returns a Boolean.
* If the return value is true, output will be sent to
* System.out, otherwise it will not.
*/
public SystemOutputInterceptor(final Closure callback) {
this(callback, true);
}
/**
* Constructor
*
* @param callback accepts a string to be sent to std out and returns a Boolean.
* If the return value is true, output will be sent to
* System.out/System.err, otherwise it will not.
* @param output flag that tells whether System.out needs capturing ot System.err
*/
public SystemOutputInterceptor(final Closure callback, boolean output) {
super(output ? System.out : System.err);
assert callback != null;
this.callback = callback;
this.output = output;
}
/**
* Starts intercepting System.out/System.err
*/
public void start() {
if (output) {
System.setOut(new PrintStream(this));
} else {
System.setErr(new PrintStream(this));
}
}
/**
* Stops intercepting System.out/System.err, sending output to wherever it was
* going when this interceptor was created.
*/
public void stop() {
if (output) {
System.setOut((PrintStream) out);
} else {
System.setErr((PrintStream) out);
}
}
/**
* Intercepts output - moret common case of byte[]
*/
public void write(byte[] b, int off, int len) throws IOException {
Boolean result = (Boolean) callback.call(new String(b, off, len));
if (result) {
out.write(b, off, len);
}
}
/**
* Intercepts output - single characters
*/
public void write(int b) throws IOException {
Boolean result = (Boolean) callback.call(String.valueOf((char) b));
if (result) {
out.write(b);
}
}
}