ByteArrayOutputStreamNoCopyUnsynchronized

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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package com.github.davidmoten.util;

import java.io.IOException;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.Arrays;

/**
 * This class implements an output stream in which the data is written into a
 * byte array. The buffer automatically grows as data is written to it. The data
 * can be retrieved using <code>toByteArray()</code> and <code>toString()</code>
 * .
 * <p>
 * Closing a <tt>ByteArrayOutputStream</tt> has no effect. The methods in this
 * class can be called after the stream has been closed without generating an
 * <tt>IOException</tt>.
 *
 * @author Arthur van Hoff
 * @since JDK1.0
 */

public class ByteArrayOutputStreamNoCopyUnsynchronized extends OutputStream {

    /**
     * The buffer where data is stored.
     */
    protected byte buf[];

    /**
     * The number of valid bytes in the buffer.
     */
    protected int count;

    /**
     * Creates a new byte array output stream. The buffer capacity is initially
     * 32 bytes, though its size increases if necessary.
     */
    public ByteArrayOutputStreamNoCopyUnsynchronized() {
        this(32);
    }

    /**
     * Creates a new byte array output stream, with a buffer capacity of the
     * specified size, in bytes.
     *
     * @param size
     *            the initial size.
     * @exception IllegalArgumentException
     *                if size is negative.
     */
    public ByteArrayOutputStreamNoCopyUnsynchronized(int size) {
        if (size < 0) {
            throw new IllegalArgumentException("Negative initial size: " + size);
        }
        buf = new byte[size];
    }

    /**
     * Increases the capacity if necessary to ensure that it can hold at least
     * the number of elements specified by the minimum capacity argument.
     *
     * @param minCapacity
     *            the desired minimum capacity
     * @throws OutOfMemoryError
     *             if {@code minCapacity < 0}. This is interpreted as a request
     *             for the unsatisfiably large capacity
     *             {@code (long) Integer.MAX_VALUE + (minCapacity - Integer.MAX_VALUE)}
     *             .
     */
    private void ensureCapacity(int minCapacity) {
        // overflow-conscious code
        if (minCapacity - buf.length > 0)
            grow(minCapacity);
    }

    /**
     * The maximum size of array to allocate. Some VMs reserve some header words
     * in an array. Attempts to allocate larger arrays may result in
     * OutOfMemoryError: Requested array size exceeds VM limit
     */
    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;

    /**
     * Increases the capacity to ensure that it can hold at least the number of
     * elements specified by the minimum capacity argument.
     *
     * @param minCapacity
     *            the desired minimum capacity
     */
    private void grow(int minCapacity) {
        // overflow-conscious code
        int oldCapacity = buf.length;
        int newCapacity = oldCapacity << 1;
        if (newCapacity - minCapacity < 0)
            newCapacity = minCapacity;
        if (newCapacity - MAX_ARRAY_SIZE > 0)
            newCapacity = hugeCapacity(minCapacity);
        buf = Arrays.copyOf(buf, newCapacity);
    }

    private static int hugeCapacity(int minCapacity) {
        if (minCapacity < 0) // overflow
            throw new OutOfMemoryError();
        return (minCapacity > MAX_ARRAY_SIZE) ? Integer.MAX_VALUE : MAX_ARRAY_SIZE;
    }

    /**
     * Writes the specified byte to this byte array output stream.
     *
     * @param b
     *            the byte to be written.
     */
    @Override
    public void write(int b) {
        ensureCapacity(count + 1);
        buf[count] = (byte) b;
        count += 1;
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array starting at
     * offset <code>off</code> to this byte array output stream.
     *
     * @param b
     *            the data.
     * @param off
     *            the start offset in the data.
     * @param len
     *            the number of bytes to write.
     */
    @Override
    public void write(byte b[], int off, int len) {
        if ((off < 0) || (off > b.length) || (len < 0) || ((off + len) - b.length > 0)) {
            throw new IndexOutOfBoundsException();
        }
        ensureCapacity(count + len);
        System.arraycopy(b, off, buf, count, len);
        count += len;
    }

    /**
     * Writes the complete contents of this byte array output stream to the
     * specified output stream argument, as if by calling the output stream's
     * write method using <code>out.write(buf, 0, count)</code>.
     *
     * @param out
     *            the output stream to which to write the data.
     * @exception IOException
     *                if an I/O error occurs.
     */
    public void writeTo(OutputStream out) throws IOException {
        out.write(buf, 0, count);
    }

    /**
     * Resets the <code>count</code> field of this byte array output stream to
     * zero, so that all currently accumulated output in the output stream is
     * discarded. The output stream can be used again, reusing the already
     * allocated buffer space.
     *
     * @see java.io.ByteArrayInputStream#reset()
     */
    public void reset() {
        count = 0;
    }

    /**
     * Creates a newly allocated byte array. Its size is the current size of
     * this output stream and the valid contents of the buffer have been copied
     * into it.
     *
     * @return the current contents of this output stream, as a byte array.
     * @see java.io.ByteArrayOutputStream#size()
     */
    public byte toByteArray()[] {
        return Arrays.copyOf(buf, count);
    }

    public byte[] toByteArrayNoCopy() {
        return buf;
    }

    /**
     * Returns the current size of the buffer.
     *
     * @return the value of the <code>count</code> field, which is the number of
     *         valid bytes in this output stream.
     * @see java.io.ByteArrayOutputStream#size()
     */
    public int size() {
        return count;
    }

    /**
     * Converts the buffer's contents into a string decoding bytes using the
     * platform's default character set. The length of the new <tt>String</tt>
     * is a function of the character set, and hence may not be equal to the
     * size of the buffer.
     *
     * <p>
     * This method always replaces malformed-input and unmappable-character
     * sequences with the default replacement string for the platform's default
     * character set. The {@linkplain java.nio.charset.CharsetDecoder} class
     * should be used when more control over the decoding process is required.
     *
     * @return String decoded from the buffer's contents.
     * @since JDK1.1
     */
    @Override
    public String toString() {
        return new String(buf, 0, count);
    }

    /**
     * Converts the buffer's contents into a string by decoding the bytes using
     * the named {@link java.nio.charset.Charset charset}. The length of the new
     * <tt>String</tt> is a function of the charset, and hence may not be equal
     * to the length of the byte array.
     *
     * <p>
     * This method always replaces malformed-input and unmappable-character
     * sequences with this charset's default replacement string. The
     * {@link java.nio.charset.CharsetDecoder} class should be used when more
     * control over the decoding process is required.
     *
     * @param charsetName
     *            the name of a supported {@link java.nio.charset.Charset
     *            charset}
     * @return String decoded from the buffer's contents.
     * @exception UnsupportedEncodingException
     *                If the named charset is not supported
     * @since JDK1.1
     */
    public String toString(String charsetName) throws UnsupportedEncodingException {
        return new String(buf, 0, count, charsetName);
    }

    /**
     * Creates a newly allocated string. Its size is the current size of the
     * output stream and the valid contents of the buffer have been copied into
     * it. Each character <i>c</i> in the resulting string is constructed from
     * the corresponding element <i>b</i> in the byte array such that:
     * <blockquote>
     *
     * <pre>
     * c == (char) (((hibyte &amp; 0xff) &lt;&lt; 8) | (b &amp; 0xff))
     * </pre>
     *
     * </blockquote>
     *
     * @deprecated This method does not properly convert bytes into characters.
     *             As of JDK&nbsp;1.1, the preferred way to do this is via the
     *             <code>toString(String enc)</code> method, which takes an
     *             encoding-name argument, or the <code>toString()</code>
     *             method, which uses the platform's default character encoding.
     *
     * @param hibyte
     *            the high byte of each resulting Unicode character.
     * @return the current contents of the output stream, as a string.
     * @see java.io.ByteArrayOutputStream#size()
     * @see java.io.ByteArrayOutputStream#toString(String)
     * @see java.io.ByteArrayOutputStream#toString()
     */
    @Deprecated
    public String toString(int hibyte) {
        return new String(buf, hibyte, 0, count);
    }

    /**
     * Closing a <tt>ByteArrayOutputStream</tt> has no effect. The methods in
     * this class can be called after the stream has been closed without
     * generating an <tt>IOException</tt>.
     */
    @Override
    public void close() throws IOException {
    }

}