content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 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
  // 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.IOException;
  
  /**
   * This class is used internally by the Protocol Buffer library and generated message
   * implementations. It is public only because those generated messages do not reside in the {@code
   * protobuf} package. Others should not use this class directly.
   *
   * <p>This class contains constants and helper functions useful for dealing with the Protocol Buffer
   * wire format.
   *
   * @author kenton@google.com Kenton Varda
   */
  public final class WireFormat {
    // Do not allow instantiation.
    private WireFormat() {}
  
    static final int FIXED32_SIZE = 4;
    static final int FIXED64_SIZE = 8;
    static final int MAX_VARINT32_SIZE = 5;
    static final int MAX_VARINT64_SIZE = 10;
    static final int MAX_VARINT_SIZE = 10;
  
    public static final int WIRETYPE_VARINT = 0;
    public static final int WIRETYPE_FIXED64 = 1;
    public static final int WIRETYPE_LENGTH_DELIMITED = 2;
    public static final int WIRETYPE_START_GROUP = 3;
    public static final int WIRETYPE_END_GROUP = 4;
    public static final int WIRETYPE_FIXED32 = 5;
  
    static final int TAG_TYPE_BITS = 3;
    static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1;
  
    /** Given a tag value, determines the wire type (the lower 3 bits). */
    public static int getTagWireType(final int tag) {
      return tag & TAG_TYPE_MASK;
    }
  
    /** Given a tag value, determines the field number (the upper 29 bits). */
    public static int getTagFieldNumber(final int tag) {
      return tag >>> TAG_TYPE_BITS;
    }
  
    /** Makes a tag value given a field number and wire type. */
    static int makeTag(final int fieldNumber, final int wireType) {
      return (fieldNumber << TAG_TYPE_BITS) | wireType;
    }
  
    /**
     * Lite equivalent to {@link Descriptors.FieldDescriptor.JavaType}. This is only here to support
     * the lite runtime and should not be used by users.
     */
    public enum JavaType {
      INT(0),
      LONG(0L),
      FLOAT(0F),
      DOUBLE(0D),
      BOOLEAN(false),
      STRING(""),
      BYTE_STRING(ByteString.EMPTY),
      ENUM(null),
      MESSAGE(null);
  
      JavaType(final Object defaultDefault) {
        this.defaultDefault = defaultDefault;
      }
  
      /** The default default value for fields of this type, if it's a primitive type. */
      Object getDefaultDefault() {
        return defaultDefault;
      }
  
      private final Object defaultDefault;
    }
  
    /**
     * Lite equivalent to {@link Descriptors.FieldDescriptor.Type}. This is only here to support the
     * lite runtime and should not be used by users.
     */
    public enum FieldType {
      DOUBLE(JavaType.DOUBLE, WIRETYPE_FIXED64),
      FLOAT(JavaType.FLOAT, WIRETYPE_FIXED32),
      INT64(JavaType.LONG, WIRETYPE_VARINT),
      UINT64(JavaType.LONG, WIRETYPE_VARINT),
      INT32(JavaType.INT, WIRETYPE_VARINT),
      FIXED64(JavaType.LONG, WIRETYPE_FIXED64),
      FIXED32(JavaType.INT, WIRETYPE_FIXED32),
      BOOL(JavaType.BOOLEAN, WIRETYPE_VARINT),
      STRING(JavaType.STRING, WIRETYPE_LENGTH_DELIMITED) {
        @Override
        public boolean isPackable() {
          return false;
        }
      },
      GROUP(JavaType.MESSAGE, WIRETYPE_START_GROUP) {
        @Override
        public boolean isPackable() {
          return false;
        }
      },
      MESSAGE(JavaType.MESSAGE, WIRETYPE_LENGTH_DELIMITED) {
        @Override
        public boolean isPackable() {
          return false;
        }
      },
      BYTES(JavaType.BYTE_STRING, WIRETYPE_LENGTH_DELIMITED) {
        @Override
        public boolean isPackable() {
          return false;
        }
      },
      UINT32(JavaType.INT, WIRETYPE_VARINT),
      ENUM(JavaType.ENUM, WIRETYPE_VARINT),
      SFIXED32(JavaType.INT, WIRETYPE_FIXED32),
      SFIXED64(JavaType.LONG, WIRETYPE_FIXED64),
      SINT32(JavaType.INT, WIRETYPE_VARINT),
      SINT64(JavaType.LONG, WIRETYPE_VARINT);
  
      FieldType(final JavaType javaType, final int wireType) {
        this.javaType = javaType;
        this.wireType = wireType;
      }
  
      private final JavaType javaType;
      private final int wireType;
  
      public JavaType getJavaType() {
        return javaType;
      }
  
      public int getWireType() {
        return wireType;
      }
  
      public boolean isPackable() {
        return true;
      }
    }
  
    // Field numbers for fields in MessageSet wire format.
    static final int MESSAGE_SET_ITEM = 1;
    static final int MESSAGE_SET_TYPE_ID = 2;
    static final int MESSAGE_SET_MESSAGE = 3;
  
    // Tag numbers.
    static final int MESSAGE_SET_ITEM_TAG = makeTag(MESSAGE_SET_ITEM, WIRETYPE_START_GROUP);
    static final int MESSAGE_SET_ITEM_END_TAG = makeTag(MESSAGE_SET_ITEM, WIRETYPE_END_GROUP);
    static final int MESSAGE_SET_TYPE_ID_TAG = makeTag(MESSAGE_SET_TYPE_ID, WIRETYPE_VARINT);
    static final int MESSAGE_SET_MESSAGE_TAG =
        makeTag(MESSAGE_SET_MESSAGE, WIRETYPE_LENGTH_DELIMITED);
  
    /**
     * Validation level for handling incoming string field data which potentially contain non-UTF8
     * bytes.
     */
    enum Utf8Validation {
      /** Eagerly parses to String; silently accepts invalid UTF8 bytes. */
      LOOSE {
        @Override
        Object readString(CodedInputStream input) throws IOException {
          return input.readString();
        }
      },
      /** Eagerly parses to String; throws an IOException on invalid bytes. */
      STRICT {
        @Override
        Object readString(CodedInputStream input) throws IOException {
          return input.readStringRequireUtf8();
        }
      },
      /** Keep data as ByteString; validation/conversion to String is lazy. */
      LAZY {
        @Override
        Object readString(CodedInputStream input) throws IOException {
          return input.readBytes();
        }
      };
  
      /** Read a string field from the input with the proper UTF8 validation. */
      abstract Object readString(CodedInputStream input) throws IOException;
    }
  
    /**
     * Read a field of any primitive type for immutable messages from a CodedInputStream. Enums,
     * groups, and embedded messages are not handled by this method.
     *
     * @param input The stream from which to read.
     * @param type Declared type of the field.
     * @param utf8Validation Different string UTF8 validation level for handling string fields.
     * @return An object representing the field's value, of the exact type which would be returned by
     *     {@link Message#getField(Descriptors.FieldDescriptor)} for this field.
     */
    static Object readPrimitiveField(
        CodedInputStream input, FieldType type, Utf8Validation utf8Validation) throws IOException {
      switch (type) {
        case DOUBLE:
          return input.readDouble();
        case FLOAT:
          return input.readFloat();
        case INT64:
          return input.readInt64();
        case UINT64:
          return input.readUInt64();
        case INT32:
          return input.readInt32();
        case FIXED64:
          return input.readFixed64();
        case FIXED32:
          return input.readFixed32();
        case BOOL:
          return input.readBool();
        case BYTES:
          return input.readBytes();
        case UINT32:
          return input.readUInt32();
        case SFIXED32:
          return input.readSFixed32();
        case SFIXED64:
          return input.readSFixed64();
        case SINT32:
          return input.readSInt32();
        case SINT64:
          return input.readSInt64();
  
        case STRING:
          return utf8Validation.readString(input);
        case GROUP:
          throw new IllegalArgumentException("readPrimitiveField() cannot handle nested groups.");
        case MESSAGE:
          throw new IllegalArgumentException("readPrimitiveField() cannot handle embedded messages.");
        case ENUM:
          // We don't handle enums because we don't know what to do if the
          // value is not recognized.
          throw new IllegalArgumentException("readPrimitiveField() cannot handle enums.");
      }
  
      throw new RuntimeException("There is no way to get here, but the compiler thinks otherwise.");
    }
  }
  