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// 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.InputStream;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.FilterOutputStream;

import java.io.UnsupportedEncodingException;

import java.nio.ByteBuffer;

import java.util.List;

/**

 * Immutable array of bytes.

 *

 * @author crazybob@google.com Bob Lee

 * @author kenton@google.com Kenton Varda

 */

public final class ByteString {

  private final byte[] bytes;

  private ByteString(final byte[] bytes) {

    this.bytes = bytes;

  }

  /**

   * Gets the byte at the given index.

   *

   * @throws ArrayIndexOutOfBoundsException {@code index} is < 0 or >= size

   */

  public byte byteAt(final int index) {

    return bytes[index];

  }

  /**

   * Gets the number of bytes.

   */

  public int size() {

    return bytes.length;

  }

  /**

   * Returns {@code true} if the size is {@code 0}, {@code false} otherwise.

   */

  public boolean isEmpty() {

    return bytes.length == 0;

  }

  // =================================================================

  // byte[] -> ByteString

  /**

   * Empty ByteString.

   */

  public static final ByteString EMPTY = new ByteString(new byte[0]);

  /**

   * Copies the given bytes into a {@code ByteString}.

   */

  public static ByteString copyFrom(final byte[] bytes, final int offset,

                                    final int size) {

    final byte[] copy = new byte[size];

    System.arraycopy(bytes, offset, copy, 0, size);

    return new ByteString(copy);

  }

  /**

   * Copies the given bytes into a {@code ByteString}.

   */

  public static ByteString copyFrom(final byte[] bytes) {

    return copyFrom(bytes, 0, bytes.length);

  }

  /**

   * Copies {@code size} bytes from a {@code java.nio.ByteBuffer} into

   * a {@code ByteString}.

   */

  public static ByteString copyFrom(final ByteBuffer bytes, final int size) {

    final byte[] copy = new byte[size];

    bytes.get(copy);

    return new ByteString(copy);

  }

  /**

   * Copies the remaining bytes from a {@code java.nio.ByteBuffer} into

   * a {@code ByteString}.

   */

  public static ByteString copyFrom(final ByteBuffer bytes) {

    return copyFrom(bytes, bytes.remaining());

  }

  /**

   * Encodes {@code text} into a sequence of bytes using the named charset

   * and returns the result as a {@code ByteString}.

   */

  public static ByteString copyFrom(final String text, final String charsetName)

      throws UnsupportedEncodingException {

    return new ByteString(text.getBytes(charsetName));

  }

  /**

   * Encodes {@code text} into a sequence of UTF-8 bytes and returns the

   * result as a {@code ByteString}.

   */

  public static ByteString copyFromUtf8(final String text) {

    try {

      return new ByteString(text.getBytes("UTF-8"));

    } catch (UnsupportedEncodingException e) {

      throw new RuntimeException("UTF-8 not supported?", e);

    }

  }

  /**

   * Concatenates all byte strings in the list and returns the result.

   *

   * <p>The returned {@code ByteString} is not necessarily a unique object.

   * If the list is empty, the returned object is the singleton empty

   * {@code ByteString}.  If the list has only one element, that

   * {@code ByteString} will be returned without copying.

   */

  public static ByteString copyFrom(List<ByteString> list) {

    if (list.size() == 0) {

      return EMPTY;

    } else if (list.size() == 1) {

      return list.get(0);

    }

    int size = 0;

    for (ByteString str : list) {

      size += str.size();

    }

    byte[] bytes = new byte[size];

    int pos = 0;

    for (ByteString str : list) {

      System.arraycopy(str.bytes, 0, bytes, pos, str.size());

      pos += str.size();

    }

    return new ByteString(bytes);

  }

  // =================================================================

  // ByteString -> byte[]

  /**

   * Copies bytes into a buffer at the given offset.

   *

   * @param target buffer to copy into

   * @param offset in the target buffer

   */

  public void copyTo(final byte[] target, final int offset) {

    System.arraycopy(bytes, 0, target, offset, bytes.length);

  }

  /**

   * Copies bytes into a buffer.

   *

   * @param target buffer to copy into

   * @param sourceOffset offset within these bytes

   * @param targetOffset offset within the target buffer

   * @param size number of bytes to copy

   */

  public void copyTo(final byte[] target, final int sourceOffset,

                     final int targetOffset,

      final int size) {

    System.arraycopy(bytes, sourceOffset, target, targetOffset, size);

  }

  /**

   * Copies bytes into a ByteBuffer.

   *

   * @param target ByteBuffer to copy into.

   * @throws ReadOnlyBufferException if the {@code target} is read-only

   * @throws BufferOverflowException if the {@code target}'s remaining()

   *         space is not large enough to hold the data.

   */

  public void copyTo(ByteBuffer target) {

    target.put(bytes, 0, bytes.length);

  }

  /**

   * Copies bytes to a {@code byte[]}.

   */

  public byte[] toByteArray() {

    final int size = bytes.length;

    final byte[] copy = new byte[size];

    System.arraycopy(bytes, 0, copy, 0, size);

    return copy;

  }

  /**

   * Constructs a new read-only {@code java.nio.ByteBuffer} with the

   * same backing byte array.

   */

  public ByteBuffer asReadOnlyByteBuffer() {

    final ByteBuffer byteBuffer = ByteBuffer.wrap(bytes);

    return byteBuffer.asReadOnlyBuffer();

  }

  /**

   * Constructs a new {@code String} by decoding the bytes using the

   * specified charset.

   */

  public String toString(final String charsetName)

      throws UnsupportedEncodingException {

    return new String(bytes, charsetName);

  }

  /**

   * Constructs a new {@code String} by decoding the bytes as UTF-8.

   */

  public String toStringUtf8() {

    try {

      return new String(bytes, "UTF-8");

    } catch (UnsupportedEncodingException e) {

      throw new RuntimeException("UTF-8 not supported?", e);

    }

  }

  // =================================================================

  // equals() and hashCode()

  @Override

  public boolean equals(final Object o) {

    if (o == this) {

      return true;

    }

    if (!(o instanceof ByteString)) {

      return false;

    }

    final ByteString other = (ByteString) o;

    final int size = bytes.length;

    if (size != other.bytes.length) {

      return false;

    }

    final byte[] thisBytes = bytes;

    final byte[] otherBytes = other.bytes;

    for (int i = 0; i < size; i++) {

      if (thisBytes[i] != otherBytes[i]) {

        return false;

      }

    }

    return true;

  }

  private volatile int hash = 0;

  @Override

  public int hashCode() {

    int h = hash;

    if (h == 0) {

      final byte[] thisBytes = bytes;

      final int size = bytes.length;

      h = size;

      for (int i = 0; i < size; i++) {

        h = h * 31 + thisBytes[i];

      }

      if (h == 0) {

        h = 1;

      }

      hash = h;

    }

    return h;

  }

  // =================================================================

  // Input stream

  /**

   * Creates an {@code InputStream} which can be used to read the bytes.

   */

  public InputStream newInput() {

    return new ByteArrayInputStream(bytes);

  }

  /**

   * Creates a {@link CodedInputStream} which can be used to read the bytes.

   * Using this is more efficient than creating a {@link CodedInputStream}

   * wrapping the result of {@link #newInput()}.

   */

  public CodedInputStream newCodedInput() {

    // We trust CodedInputStream not to modify the bytes, or to give anyone

    // else access to them.

    return CodedInputStream.newInstance(bytes);

  }

  // =================================================================

  // Output stream

  /**

   * Creates a new {@link Output} with the given initial capacity.

   */

  public static Output newOutput(final int initialCapacity) {

    return new Output(new ByteArrayOutputStream(initialCapacity));

  }

  /**

   * Creates a new {@link Output}.

   */

  public static Output newOutput() {

    return newOutput(32);

  }

  /**

   * Outputs to a {@code ByteString} instance. Call {@link #toByteString()} to

   * create the {@code ByteString} instance.

   */

  public static final class Output extends FilterOutputStream {

    private final ByteArrayOutputStream bout;

    /**

     * Constructs a new output with the given initial capacity.

     */

    private Output(final ByteArrayOutputStream bout) {

      super(bout);

      this.bout = bout;

    }

    /**

     * Creates a {@code ByteString} instance from this {@code Output}.

     */

    public ByteString toByteString() {

      final byte[] byteArray = bout.toByteArray();

      return new ByteString(byteArray);

    }

  }

  /**

   * Constructs a new ByteString builder, which allows you to efficiently

   * construct a {@code ByteString} by writing to a {@link CodedOutputStream}.

   * Using this is much more efficient than calling {@code newOutput()} and

   * wrapping that in a {@code CodedOutputStream}.

   *

   * <p>This is package-private because it's a somewhat confusing interface.

   * Users can call {@link Message#toByteString()} instead of calling this

   * directly.

   *

   * @param size The target byte size of the {@code ByteString}.  You must

   *             write exactly this many bytes before building the result.

   */

  static CodedBuilder newCodedBuilder(final int size) {

    return new CodedBuilder(size);

  }

  /** See {@link ByteString#newCodedBuilder(int)}. */

  static final class CodedBuilder {

    private final CodedOutputStream output;

    private final byte[] buffer;

    private CodedBuilder(final int size) {

      buffer = new byte[size];

      output = CodedOutputStream.newInstance(buffer);

    }

    public ByteString build() {

      output.checkNoSpaceLeft();

      // We can be confident that the CodedOutputStream will not modify the

      // underlying bytes anymore because it already wrote all of them.  So,

      // no need to make a copy.

      return new ByteString(buffer);

    }

    public CodedOutputStream getCodedOutput() {

      return output;

    }

  }

}