org.apache.myfaces.shared_tomahawk.util.io.DynamicPushbackInputStream Maven / Gradle / Ivy

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JSF components and utilities that can be used with any JSF implementation. This library is based on the JSF1.1 version of Tomahawk, but with minor source code and build changes to take advantage of JSF2.1 features. A JSF2.1 implementation is required to use this version of the Tomahawk library.

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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.apache.myfaces.shared_tomahawk.util.io;

import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;

/**
 * NOTE: Copy of org.apache.abdera.i18n.text.io.DynamicPushbackInputStream
 * 
 * PushbackInputStream implementation that performs dynamic resizing of the unread buffer
 */
public class DynamicPushbackInputStream extends PushbackInputStream
{

    private final int origsize;

    public DynamicPushbackInputStream(InputStream in)
    {
        super(in);
        this.origsize = 1;
    }

    public DynamicPushbackInputStream(InputStream in, int initialSize)
    {
        super(in, initialSize);
        this.origsize = initialSize;
    }

    /**
     * Clear the buffer
     */
    public int clear()
    {
        int m = buf.length;
        buf = new byte[origsize];
        pos = origsize;
        return m;
    }

    /**
     * Shrink the buffer. This will reclaim currently unused space in the buffer, reducing memory but potentially
     * increasing the cost of resizing the buffer
     */
    public int shrink()
    {
        byte[] old = buf;
        if (pos == 0)
        {
            return 0; // nothing to do
        }
        int n = old.length - pos;
        int m;
        int p;
        int s;
        int l;
        if (n < origsize)
        {
            buf = new byte[origsize];
            p = pos;
            s = origsize - n;
            l = old.length - p;
            m = old.length - origsize;
            pos = s;
        }
        else
        {
            buf = new byte[n];
            p = pos;
            s = 0;
            l = n;
            m = old.length - l;
            pos = 0;
        }
        System.arraycopy(old, p, buf, s, l);
        return m;
    }

    private void resize(int len)
    {
        byte[] old = buf;
        buf = new byte[old.length + len];
        System.arraycopy(old, 0, buf, len, old.length);
    }

    public void unread(byte[] b, int off, int len) throws IOException
    {
        if (len > pos && pos + len > buf.length)
        {
            resize(len - pos);
            pos += len - pos;
        }
        super.unread(b, off, len);
    }

    public void unread(int b) throws IOException
    {
        if (pos == 0)
        {
            resize(1);
            pos++;
        }
        super.unread(b);
    }

    public int read() throws IOException
    {
        int m = super.read();
        if (pos >= buf.length && buf.length > origsize)
        {
            shrink();
        }
        return m;
    }

    public int read(byte[] b, int off, int len) throws IOException
    {
        this.available(); // workaround for a problem in PushbackInputStream, without this, the amount of bytes read
                          // from some streams will be incorrect
        int r = super.read(b, off, len);
        if (pos >= buf.length && buf.length > origsize)
        {
            shrink();
        }
        return r;
    }

    public long skip(long n) throws IOException
    {
        long r = super.skip(n);
        if (pos >= buf.length && buf.length > origsize)
        {
            shrink();
        }
        return r;
    }
}