ByteVector.java

/*
 *   ASM: a very small and fast Java bytecode manipulation framework
 *   Copyright (c) 2000-2007 INRIA, France Telecom
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *   3. Neither the name of the copyright holders nor the names of its
 *      contributors may be used to endorse or promote products derived from
 *      this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 *   AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *   IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *   ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 *   LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *   CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *   SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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 *   ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 *   THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.powermock.objectweb.asm;

/**
 * A dynamically extensible vector of bytes. This class is roughly equivalent to
 * a DataOutputStream on top of a ByteArrayOutputStream, but is more efficient.
 * 
 * @author Eric Bruneton
 */
public class ByteVector {

    /**
     * The content of this vector.
     */
    byte[] data;

    /**
     * Actual number of bytes in this vector.
     */
    int length;

    /**
     * Constructs a new {@link ByteVector ByteVector} with a default initial
     * size.
     */
    public ByteVector() {
        data = new byte[64];
    }

    /**
     * Constructs a new {@link ByteVector ByteVector} with the given initial
     * size.
     * 
     * @param initialSize
     *            the initial size of the byte vector to be constructed.
     */
    public ByteVector(final int initialSize) {
        data = new byte[initialSize];
    }

    /**
     * Puts a byte into this byte vector. The byte vector is automatically
     * enlarged if necessary.
     * 
     * @param b
     *            a byte.
     * @return this byte vector.
     */
    public ByteVector putByte(final int b) {
        int length = this.length;
        if (length + 1 > data.length) {
            enlarge(1);
        }
        data[length++] = (byte) b;
        this.length = length;
        return this;
    }

    /**
     * Puts two bytes into this byte vector. The byte vector is automatically
     * enlarged if necessary.
     * 
     * @param b1
     *            a byte.
     * @param b2
     *            another byte.
     * @return this byte vector.
     */
    ByteVector put11(final int b1, final int b2) {
        int length = this.length;
        if (length + 2 > data.length) {
            enlarge(2);
        }
        byte[] data = this.data;
        data[length++] = (byte) b1;
        data[length++] = (byte) b2;
        this.length = length;
        return this;
    }

    /**
     * Puts a short into this byte vector. The byte vector is automatically
     * enlarged if necessary.
     * 
     * @param s
     *            a short.
     * @return this byte vector.
     */
    public ByteVector putShort(final int s) {
        int length = this.length;
        if (length + 2 > data.length) {
            enlarge(2);
        }
        byte[] data = this.data;
        data[length++] = (byte) (s >>> 8);
        data[length++] = (byte) s;
        this.length = length;
        return this;
    }

    /**
     * Puts a byte and a short into this byte vector. The byte vector is
     * automatically enlarged if necessary.
     * 
     * @param b
     *            a byte.
     * @param s
     *            a short.
     * @return this byte vector.
     */
    ByteVector put12(final int b, final int s) {
        int length = this.length;
        if (length + 3 > data.length) {
            enlarge(3);
        }
        byte[] data = this.data;
        data[length++] = (byte) b;
        data[length++] = (byte) (s >>> 8);
        data[length++] = (byte) s;
        this.length = length;
        return this;
    }

    /**
     * Puts an int into this byte vector. The byte vector is automatically
     * enlarged if necessary.
     * 
     * @param i
     *            an int.
     * @return this byte vector.
     */
    public ByteVector putInt(final int i) {
        int length = this.length;
        if (length + 4 > data.length) {
            enlarge(4);
        }
        byte[] data = this.data;
        data[length++] = (byte) (i >>> 24);
        data[length++] = (byte) (i >>> 16);
        data[length++] = (byte) (i >>> 8);
        data[length++] = (byte) i;
        this.length = length;
        return this;
    }

    /**
     * Puts a long into this byte vector. The byte vector is automatically
     * enlarged if necessary.
     * 
     * @param l
     *            a long.
     * @return this byte vector.
     */
    public ByteVector putLong(final long l) {
        int length = this.length;
        if (length + 8 > data.length) {
            enlarge(8);
        }
        byte[] data = this.data;
        int i = (int) (l >>> 32);
        data[length++] = (byte) (i >>> 24);
        data[length++] = (byte) (i >>> 16);
        data[length++] = (byte) (i >>> 8);
        data[length++] = (byte) i;
        i = (int) l;
        data[length++] = (byte) (i >>> 24);
        data[length++] = (byte) (i >>> 16);
        data[length++] = (byte) (i >>> 8);
        data[length++] = (byte) i;
        this.length = length;
        return this;
    }

    /**
     * Puts an UTF8 string into this byte vector. The byte vector is
     * automatically enlarged if necessary.
     * 
     * @param s
     *            a String whose UTF8 encoded length must be less than 65536.
     * @return this byte vector.
     */
    public ByteVector putUTF8(final String s) {
        int charLength = s.length();
        if (charLength > 65535) {
            throw new IllegalArgumentException();
        }
        int len = length;
        if (len + 2 + charLength > data.length) {
            enlarge(2 + charLength);
        }
        byte[] data = this.data;
        // optimistic algorithm: instead of computing the byte length and then
        // serializing the string (which requires two loops), we assume the byte
        // length is equal to char length (which is the most frequent case), and
        // we start serializing the string right away. During the serialization,
        // if we find that this assumption is wrong, we continue with the
        // general method.
        data[len++] = (byte) (charLength >>> 8);
        data[len++] = (byte) charLength;
        for (int i = 0; i < charLength; ++i) {
            char c = s.charAt(i);
            if (c >= '\001' && c <= '\177') {
                data[len++] = (byte) c;
            } else {
                length = len;
                return encodeUTF8(s, i, 65535);
            }
        }
        length = len;
        return this;
    }

    /**
     * Puts an UTF8 string into this byte vector. The byte vector is
     * automatically enlarged if necessary. The string length is encoded in two
     * bytes before the encoded characters, if there is space for that (i.e. if
     * this.length - i - 2 >= 0).
     * 
     * @param s
     *            the String to encode.
     * @param i
     *            the index of the first character to encode. The previous
     *            characters are supposed to have already been encoded, using
     *            only one byte per character.
     * @param maxByteLength
     *            the maximum byte length of the encoded string, including the
     *            already encoded characters.
     * @return this byte vector.
     */
    ByteVector encodeUTF8(final String s, int i, int maxByteLength) {
        int charLength = s.length();
        int byteLength = i;
        char c;
        for (int j = i; j < charLength; ++j) {
            c = s.charAt(j);
            if (c >= '\001' && c <= '\177') {
                byteLength++;
            } else if (c > '\u07FF') {
                byteLength += 3;
            } else {
                byteLength += 2;
            }
        }
        if (byteLength > maxByteLength) {
            throw new IllegalArgumentException();
        }
        int start = length - i - 2;
        if (start >= 0) {
          data[start] = (byte) (byteLength >>> 8);
          data[start + 1] = (byte) byteLength;
        }
        if (length + byteLength - i > data.length) {
            enlarge(byteLength - i);
        }
        int len = length;
        for (int j = i; j < charLength; ++j) {
            c = s.charAt(j);
            if (c >= '\001' && c <= '\177') {
                data[len++] = (byte) c;
            } else if (c > '\u07FF') {
                data[len++] = (byte) (0xE0 | c >> 12 & 0xF);
                data[len++] = (byte) (0x80 | c >> 6 & 0x3F);
                data[len++] = (byte) (0x80 | c & 0x3F);
            } else {
                data[len++] = (byte) (0xC0 | c >> 6 & 0x1F);
                data[len++] = (byte) (0x80 | c & 0x3F);
            }
        }
        length = len;
        return this;
    }

    /**
     * Puts an array of bytes into this byte vector. The byte vector is
     * automatically enlarged if necessary.
     * 
     * @param b
     *            an array of bytes. May be <tt>null</tt> to put <tt>len</tt>
     *            null bytes into this byte vector.
     * @param off
     *            index of the fist byte of b that must be copied.
     * @param len
     *            number of bytes of b that must be copied.
     * @return this byte vector.
     */
    public ByteVector putByteArray(final byte[] b, final int off, final int len) {
        if (length + len > data.length) {
            enlarge(len);
        }
        if (b != null) {
            System.arraycopy(b, off, data, length, len);
        }
        length += len;
        return this;
    }

    /**
     * Enlarge this byte vector so that it can receive n more bytes.
     * 
     * @param size
     *            number of additional bytes that this byte vector should be
     *            able to receive.
     */
    private void enlarge(final int size) {
        int length1 = 2 * data.length;
        int length2 = length + size;
        byte[] newData = new byte[length1 > length2 ? length1 : length2];
        System.arraycopy(data, 0, newData, 0, length);
        data = newData;
    }
}