1// Protocol Buffers - Google's data interchange format 2// Copyright 2013 Google Inc. All rights reserved. 3// https://developers.google.com/protocol-buffers/ 4// 5// Redistribution and use in source and binary forms, with or without 6// modification, are permitted provided that the following conditions are 7// met: 8// 9// * Redistributions of source code must retain the above copyright 10// notice, this list of conditions and the following disclaimer. 11// * Redistributions in binary form must reproduce the above 12// copyright notice, this list of conditions and the following disclaimer 13// in the documentation and/or other materials provided with the 14// distribution. 15// * Neither the name of Google Inc. nor the names of its 16// contributors may be used to endorse or promote products derived from 17// this software without specific prior written permission. 18// 19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31package com.google.protobuf.nano; 32 33import java.io.IOException; 34 35/** 36 * This class is used internally by the Protocol Buffer library and generated 37 * message implementations. It is public only because those generated messages 38 * do not reside in the {@code protobuf} package. Others should not use this 39 * class directly. 40 * 41 * This class contains constants and helper functions useful for dealing with 42 * the Protocol Buffer wire format. 43 * 44 * @author kenton@google.com Kenton Varda 45 */ 46public final class WireFormatNano { 47 // Do not allow instantiation. 48 private WireFormatNano() {} 49 50 static final int WIRETYPE_VARINT = 0; 51 static final int WIRETYPE_FIXED64 = 1; 52 static final int WIRETYPE_LENGTH_DELIMITED = 2; 53 static final int WIRETYPE_START_GROUP = 3; 54 static final int WIRETYPE_END_GROUP = 4; 55 static final int WIRETYPE_FIXED32 = 5; 56 57 static final int TAG_TYPE_BITS = 3; 58 static final int TAG_TYPE_MASK = (1 << TAG_TYPE_BITS) - 1; 59 60 /** Given a tag value, determines the wire type (the lower 3 bits). */ 61 static int getTagWireType(final int tag) { 62 return tag & TAG_TYPE_MASK; 63 } 64 65 /** Given a tag value, determines the field number (the upper 29 bits). */ 66 public static int getTagFieldNumber(final int tag) { 67 return tag >>> TAG_TYPE_BITS; 68 } 69 70 /** Makes a tag value given a field number and wire type. */ 71 static int makeTag(final int fieldNumber, final int wireType) { 72 return (fieldNumber << TAG_TYPE_BITS) | wireType; 73 } 74 75 public static final int EMPTY_INT_ARRAY[] = {}; 76 public static final long EMPTY_LONG_ARRAY[] = {}; 77 public static final float EMPTY_FLOAT_ARRAY[] = {}; 78 public static final double EMPTY_DOUBLE_ARRAY[] = {}; 79 public static final boolean EMPTY_BOOLEAN_ARRAY[] = {}; 80 public static final String EMPTY_STRING_ARRAY[] = {}; 81 public static final byte[] EMPTY_BYTES_ARRAY[] = {}; 82 public static final byte[] EMPTY_BYTES = {}; 83 84 /** 85 * Parses an unknown field. This implementation skips the field. 86 * 87 * <p>Generated messages will call this for unknown fields if the store_unknown_fields 88 * option is off. 89 * 90 * @return {@literal true} unless the tag is an end-group tag. 91 */ 92 public static boolean parseUnknownField( 93 final CodedInputByteBufferNano input, 94 final int tag) throws IOException { 95 return input.skipField(tag); 96 } 97 98 /** 99 * Computes the array length of a repeated field. We assume that in the common case repeated 100 * fields are contiguously serialized but we still correctly handle interspersed values of a 101 * repeated field (but with extra allocations). 102 * 103 * Rewinds to current input position before returning. 104 * 105 * @param input stream input, pointing to the byte after the first tag 106 * @param tag repeated field tag just read 107 * @return length of array 108 * @throws IOException 109 */ 110 public static final int getRepeatedFieldArrayLength( 111 final CodedInputByteBufferNano input, 112 final int tag) throws IOException { 113 int arrayLength = 1; 114 int startPos = input.getPosition(); 115 input.skipField(tag); 116 while (input.readTag() == tag) { 117 input.skipField(tag); 118 arrayLength++; 119 } 120 input.rewindToPosition(startPos); 121 return arrayLength; 122 } 123 124} 125