content: // Protocol Buffers - Google's data interchange format
  // Copyright 2013 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // 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
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  // (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.nano;
  
  import java.io.IOException;
  import java.util.Arrays;
  
  /**
   * Abstract interface implemented by Protocol Message objects.
   *
   * @author wink@google.com Wink Saville
   */
  public abstract class MessageNano {
      protected volatile int cachedSize = -1;
  
      /**
       * Get the number of bytes required to encode this message.
       * Returns the cached size or calls getSerializedSize which
       * sets the cached size. This is used internally when serializing
       * so the size is only computed once. If a member is modified
       * then this could be stale call getSerializedSize if in doubt.
       */
      public int getCachedSize() {
          if (cachedSize < 0) {
              // getSerializedSize sets cachedSize
              getSerializedSize();
          }
          return cachedSize;
      }
  
      /**
       * Computes the number of bytes required to encode this message.
       * The size is cached and the cached result can be retrieved
       * using getCachedSize().
       */
      public int getSerializedSize() {
          int size = computeSerializedSize();
          cachedSize = size;
          return size;
      }
  
      /**
       * Computes the number of bytes required to encode this message. This does not update the
       * cached size.
       */
      protected int computeSerializedSize() {
        // This is overridden if the generated message has serialized fields.
        return 0;
      }
  
      /**
       * Serializes the message and writes it to {@code output}.
       *
       * @param output the output to receive the serialized form.
       * @throws IOException if an error occurred writing to {@code output}.
       */
      public void writeTo(CodedOutputByteBufferNano output) throws IOException {
          // Does nothing by default. Overridden by subclasses which have data to write.
      }
  
      /**
       * Parse {@code input} as a message of this type and merge it with the
       * message being built.
       */
      public abstract MessageNano mergeFrom(CodedInputByteBufferNano input) throws IOException;
  
      /**
       * Serialize to a byte array.
       * @return byte array with the serialized data.
       */
      public static final byte[] toByteArray(MessageNano msg) {
          final byte[] result = new byte[msg.getSerializedSize()];
          toByteArray(msg, result, 0, result.length);
          return result;
      }
  
      /**
       * Serialize to a byte array starting at offset through length. The
       * method getSerializedSize must have been called prior to calling
       * this method so the proper length is know.  If an attempt to
       * write more than length bytes OutOfSpaceException will be thrown
       * and if length bytes are not written then IllegalStateException
       * is thrown.
       */
      public static final void toByteArray(MessageNano msg, byte[] data, int offset, int length) {
          try {
              final CodedOutputByteBufferNano output =
                  CodedOutputByteBufferNano.newInstance(data, offset, length);
              msg.writeTo(output);
              output.checkNoSpaceLeft();
          } catch (IOException e) {
              throw new RuntimeException("Serializing to a byte array threw an IOException "
                      + "(should never happen).", e);
          }
      }
  
      /**
       * Parse {@code data} as a message of this type and merge it with the
       * message being built.
       */
      public static final <T extends MessageNano> T mergeFrom(T msg, final byte[] data)
          throws InvalidProtocolBufferNanoException {
          return mergeFrom(msg, data, 0, data.length);
      }
  
      /**
       * Parse {@code data} as a message of this type and merge it with the
       * message being built.
       */
      public static final <T extends MessageNano> T mergeFrom(T msg, final byte[] data,
              final int off, final int len) throws InvalidProtocolBufferNanoException {
          try {
              final CodedInputByteBufferNano input =
                  CodedInputByteBufferNano.newInstance(data, off, len);
              msg.mergeFrom(input);
              input.checkLastTagWas(0);
              return msg;
          } catch (InvalidProtocolBufferNanoException e) {
              throw e;
          } catch (IOException e) {
              throw new RuntimeException("Reading from a byte array threw an IOException (should "
                      + "never happen).");
          }
      }
  
      /**
       * Compares two {@code MessageNano}s and returns true if the message's are the same class and
       * have serialized form equality (i.e. all of the field values are the same).
       */
      public static final boolean messageNanoEquals(MessageNano a, MessageNano b) {
          if (a == b) {
              return true;
          }
          if (a == null || b == null) {
              return false;
          }
          if (a.getClass() != b.getClass()) {
            return false;
          }
          final int serializedSize = a.getSerializedSize();
          if (b.getSerializedSize() != serializedSize) {
              return false;
          }
          final byte[] aByteArray = new byte[serializedSize];
          final byte[] bByteArray = new byte[serializedSize];
          toByteArray(a, aByteArray, 0, serializedSize);
          toByteArray(b, bByteArray, 0, serializedSize);
          return Arrays.equals(aByteArray, bByteArray);
      }
  
      /**
       * Returns a string that is (mostly) compatible with ProtoBuffer's TextFormat. Note that groups
       * (which are deprecated) are not serialized with the correct field name.
       *
       * <p>This is implemented using reflection, so it is not especially fast nor is it guaranteed
       * to find all fields if you have method removal turned on for proguard.
       */
      @Override
      public String toString() {
          return MessageNanoPrinter.print(this);
      }
  }
  