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/*
 * 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.netbeans.lib.nbjshell;

import java.io.InputStream;

/**
 *
 * @author sdedic
 */
public class PipeInputStream extends InputStream {
    
    public static final int INITIAL_SIZE = 128;
    private int[] buffer = new int[INITIAL_SIZE];
    private int start;
    private int end;
    private boolean closed;

    @Override
    public synchronized int read() {
        while (start == end) {
            if (closed) {
                return -1;
            }
            try {
                wait();
            } catch (InterruptedException ex) {
                //ignore
            }
        }
        try {
            return buffer[start];
        } finally {
            start = (start + 1) % buffer.length;
        }
    }

    public synchronized void write(int b) {
        if (closed) {
            throw new IllegalStateException("Already closed.");
        }
        int newEnd = (end + 1) % buffer.length;
        if (newEnd == start) {
            //overflow:
            int[] newBuffer = new int[buffer.length * 2];
            int rightPart = (end > start ? end : buffer.length) - start;
            int leftPart = end > start ? 0 : start - 1;
            System.arraycopy(buffer, start, newBuffer, 0, rightPart);
            System.arraycopy(buffer, 0, newBuffer, rightPart, leftPart);
            buffer = newBuffer;
            start = 0;
            end = rightPart + leftPart;
            newEnd = end + 1;
        }
        buffer[end] = b;
        end = newEnd;
        notifyAll();
    }

    @Override
    public synchronized void close() {
        closed = true;
        notifyAll();
    }
    
}