/*
* 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.
*/
public class
SystemOutputInterceptor extends
FilterOutputStream {
private
Closure callback;
private boolean
output;
private static final
ThreadLocal<
Integer>
consoleId = new
InheritableThreadLocal<
Integer>() {
@
Override
protected
Integer initialValue() {
return
Integer.
valueOf(0);
}
};
/**
* Constructor
*
* @param callback accepts the id of the target Console instance and 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 the id of the target Console instance and 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 - more common case of byte[]
*/
public void
write(byte[]
b, int
off, int
len) throws
IOException {
Boolean result = (
Boolean)
callback.
call(
consoleId.
get(), 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(
consoleId.
get(),
String.
valueOf((char)
b));
if (
result) {
out.
write(
b);
}
}
/**
* Threads executing a script should call this method at the start of execution
* in order to set the id of the console that is hosting the thread of execution. This
* should be called prior to any output that is generated. The consoleId will
* be passed to the callback.
*
* @param consoleId id of the Console instance executing the script
*/
public void
setConsoleId(int
consoleId) {
this.
consoleId.
set(
Integer.
valueOf(
consoleId));
}
/**
* Threads executing a script should call this method after
* execution completes in order to unregister the consoleId.
*/
public void
removeConsoleId() {
this.
consoleId.
remove();
}
}