gshell-support/gshell-io/src/main/java/org/apache/geronimo/gshell/io/StreamPair.java

/*
 * 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 org.apache.geronimo.gshell.io;

import org.apache.geronimo.gshell.yarn.Yarn;

import java.io.PrintStream;

/**
 * Contains a pair of {@link PrintStream} objects.
 *
 * @version $Rev$ $Date$
 */
public class StreamPair
{
    public final PrintStream out;
    
    public final PrintStream err;
    
    public final boolean combined;
    
    public StreamPair(final PrintStream out, final PrintStream err) {
        assert out != null;
        assert err != null;
        
        this.out = out;
        this.err = err;
        this.combined = (out == err);
    }
    
    public StreamPair(final PrintStream out) {
        assert out != null;
        
        this.out = out;
        this.err = out;
        this.combined = true;
    }
    
    public PrintStream get(final Type type) {
        assert type != null;

        return type.get(this);
    }

    public String toString() {
        return Yarn.render(this);
    }

    public void flush() {
        Flusher.flush(out);

        if (!combined) {
            Flusher.flush(err);
        }
    }
    
    public void close() {
        Closer.close(out);

        if (!combined) {
            Closer.close(err);
        }
    }

    /**
     * Create a new pair as System is currently configured.
     */
    public static StreamPair system() {
        return new StreamPair(System.out, System.err);
    }

    /**
     * Install the given stream pair as the System streams.
     */
    public static void system(final StreamPair streams) {
        assert streams != null;

        System.setOut(streams.out);
        System.setErr(streams.err);
    }

    /**
     * The original System streams (as they were when this class loads).
     */
    public static final StreamPair SYSTEM = system();

    /**
     * Stream type.
     */
    public static enum Type
    {
        OUT, ERR;

        private PrintStream get(final StreamPair pair) {
            assert pair != null;

            switch (this) {
                case OUT:
                    return pair.out;

                case ERR:
                    return pair.err;
            }

            // Should never happen
            throw new InternalError();
        }
    }
}