root/third_party/protobuf/java/src/main/java/com/google/protobuf/LiteralByteString.java

DEFINITIONS

1. byteAt
2. size
3. substring
4. copyToInternal
5. copyTo
6. asReadOnlyByteBuffer
7. asReadOnlyByteBufferList
8. writeTo
9. toString
10. isValidUtf8
11. partialIsValidUtf8
12. equals
13. equalsRange
14. hashCode
15. peekCachedHashCode
16. partialHash
17. newInput
18. newCodedInput
19. iterator
20. hasNext
21. next
22. nextByte
23. remove
24. getTreeDepth
25. isBalanced
26. getOffsetIntoBytes

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// http://code.google.com/p/protobuf/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * 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.
//     * Neither the name of Google Inc. 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 INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package com.google.protobuf;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;

/**
 * This class implements a {@link com.google.protobuf.ByteString} backed by a
 * single array of bytes, contiguous in memory. It supports substring by
 * pointing to only a sub-range of the underlying byte array, meaning that a
 * substring will reference the full byte-array of the string it's made from,
 * exactly as with {@link String}.
 *
 * @author carlanton@google.com (Carl Haverl)
 */
class LiteralByteString extends ByteString {

  protected final byte[] bytes;

  /**
   * Creates a {@code LiteralByteString} backed by the given array, without
   * copying.
   *
   * @param bytes array to wrap
   */
  LiteralByteString(byte[] bytes) {
    this.bytes = bytes;
  }

  @Override
  public byte byteAt(int index) {
    // Unlike most methods in this class, this one is a direct implementation
    // ignoring the potential offset because we need to do range-checking in the
    // substring case anyway.
    return bytes[index];
  }

  @Override
  public int size() {
    return bytes.length;
  }

  // =================================================================
  // ByteString -> substring

  @Override
  public ByteString substring(int beginIndex, int endIndex) {
    if (beginIndex < 0) {
      throw new IndexOutOfBoundsException(
          "Beginning index: " + beginIndex + " < 0");
    }
    if (endIndex > size()) {
      throw new IndexOutOfBoundsException("End index: " + endIndex + " > " +
          size());
    }
    int substringLength = endIndex - beginIndex;
    if (substringLength < 0) {
      throw new IndexOutOfBoundsException(
          "Beginning index larger than ending index: " + beginIndex + ", "
              + endIndex);
    }

    ByteString result;
    if (substringLength == 0) {
      result = ByteString.EMPTY;
    } else {
      result = new BoundedByteString(bytes, getOffsetIntoBytes() + beginIndex,
          substringLength);
    }
    return result;
  }

  // =================================================================
  // ByteString -> byte[]

  @Override
  protected void copyToInternal(byte[] target, int sourceOffset, 
      int targetOffset, int numberToCopy) {
    // Optimized form, not for subclasses, since we don't call
    // getOffsetIntoBytes() or check the 'numberToCopy' parameter.
    System.arraycopy(bytes, sourceOffset, target, targetOffset, numberToCopy);
  }

  @Override
  public void copyTo(ByteBuffer target) {
    target.put(bytes, getOffsetIntoBytes(), size());  // Copies bytes
  }

  @Override
  public ByteBuffer asReadOnlyByteBuffer() {
    ByteBuffer byteBuffer =
        ByteBuffer.wrap(bytes, getOffsetIntoBytes(), size());
    return byteBuffer.asReadOnlyBuffer();
  }

  @Override
  public List<ByteBuffer> asReadOnlyByteBufferList() {
    // Return the ByteBuffer generated by asReadOnlyByteBuffer() as a singleton
    List<ByteBuffer> result = new ArrayList<ByteBuffer>(1);
    result.add(asReadOnlyByteBuffer());
    return result;
 }

 @Override
  public void writeTo(OutputStream outputStream) throws IOException {
    outputStream.write(toByteArray());
  }

  @Override
  public String toString(String charsetName)
      throws UnsupportedEncodingException {
    return new String(bytes, getOffsetIntoBytes(), size(), charsetName);
  }

  // =================================================================
  // UTF-8 decoding

  @Override
  public boolean isValidUtf8() {
    int offset = getOffsetIntoBytes();
    return Utf8.isValidUtf8(bytes, offset, offset + size());
  }

  @Override
  protected int partialIsValidUtf8(int state, int offset, int length) {
    int index = getOffsetIntoBytes() + offset;
    return Utf8.partialIsValidUtf8(state, bytes, index, index + length);
  }

  // =================================================================
  // equals() and hashCode()

  @Override
  public boolean equals(Object other) {
    if (other == this) {
      return true;
    }
    if (!(other instanceof ByteString)) {
      return false;
    }

    if (size() != ((ByteString) other).size()) {
      return false;
    }
    if (size() == 0) {
      return true;
    }

    if (other instanceof LiteralByteString) {
      return equalsRange((LiteralByteString) other, 0, size());
    } else if (other instanceof RopeByteString) {
      return other.equals(this);
    } else {
      throw new IllegalArgumentException(
          "Has a new type of ByteString been created? Found "
              + other.getClass());
    }
  }

  /**
   * Check equality of the substring of given length of this object starting at
   * zero with another {@code LiteralByteString} substring starting at offset.
   *
   * @param other  what to compare a substring in
   * @param offset offset into other
   * @param length number of bytes to compare
   * @return true for equality of substrings, else false.
   */
  boolean equalsRange(LiteralByteString other, int offset, int length) {
    if (length > other.size()) {
      throw new IllegalArgumentException(
          "Length too large: " + length + size());
    }
    if (offset + length > other.size()) {
      throw new IllegalArgumentException(
          "Ran off end of other: " + offset + ", " + length + ", " +
              other.size());
    }

    byte[] thisBytes = bytes;
    byte[] otherBytes = other.bytes;
    int thisLimit = getOffsetIntoBytes() + length;
    for (int thisIndex = getOffsetIntoBytes(), otherIndex =
        other.getOffsetIntoBytes() + offset;
        (thisIndex < thisLimit); ++thisIndex, ++otherIndex) {
      if (thisBytes[thisIndex] != otherBytes[otherIndex]) {
        return false;
      }
    }
    return true;
  }

  /**
   * Cached hash value.  Intentionally accessed via a data race, which
   * is safe because of the Java Memory Model's "no out-of-thin-air values"
   * guarantees for ints.
   */
  private int hash = 0;

  /**
   * Compute the hashCode using the traditional algorithm from {@link
   * ByteString}.
   *
   * @return hashCode value
   */
  @Override
  public int hashCode() {
    int h = hash;

    if (h == 0) {
      int size = size();
      h = partialHash(size, 0, size);
      if (h == 0) {
        h = 1;
      }
      hash = h;
    }
    return h;
  }

  @Override
  protected int peekCachedHashCode() {
    return hash;
  }

  @Override
  protected int partialHash(int h, int offset, int length) {
    byte[] thisBytes = bytes;
    for (int i = getOffsetIntoBytes() + offset, limit = i + length; i < limit;
        i++) {
      h = h * 31 + thisBytes[i];
    }
    return h;
  }

  // =================================================================
  // Input stream

  @Override
  public InputStream newInput() {
    return new ByteArrayInputStream(bytes, getOffsetIntoBytes(),
        size());  // No copy
  }

  @Override
  public CodedInputStream newCodedInput() {
    // We trust CodedInputStream not to modify the bytes, or to give anyone
    // else access to them.
    return CodedInputStream
        .newInstance(bytes, getOffsetIntoBytes(), size());  // No copy
  }

  // =================================================================
  // ByteIterator

  @Override
  public ByteIterator iterator() {
    return new LiteralByteIterator();
  }

  private class LiteralByteIterator implements ByteIterator {
    private int position;
    private final int limit;

    private LiteralByteIterator() {
      position = 0;
      limit = size();
    }

    public boolean hasNext() {
      return (position < limit);
    }

    public Byte next() {
      // Boxing calls Byte.valueOf(byte), which does not instantiate.
      return nextByte();
    }

    public byte nextByte() {
      try {
        return bytes[position++];
      } catch (ArrayIndexOutOfBoundsException e) {
        throw new NoSuchElementException(e.getMessage());
      }
    }

    public void remove() {
      throw new UnsupportedOperationException();
    }
  }

  // =================================================================
  // Internal methods

  @Override
  protected int getTreeDepth() {
    return 0;
  }

  @Override
  protected boolean isBalanced() {
    return true;
  }

  /**
   * Offset into {@code bytes[]} to use, non-zero for substrings.
   *
   * @return always 0 for this class
   */
  protected int getOffsetIntoBytes() {
    return 0;
  }
}