1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 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 31 // Authors: wink (at) google.com (Wink Saville), 32 // kenton (at) google.com (Kenton Varda) 33 // Based on original Protocol Buffers design by 34 // Sanjay Ghemawat, Jeff Dean, and others. 35 // 36 // Defines MessageLite, the abstract interface implemented by all (lite 37 // and non-lite) protocol message objects. 38 39 #ifndef GOOGLE_PROTOBUF_MESSAGE_LITE_H__ 40 #define GOOGLE_PROTOBUF_MESSAGE_LITE_H__ 41 42 #include <google/protobuf/stubs/common.h> 43 44 namespace google { 45 namespace protobuf { 46 47 namespace io { 48 class CodedInputStream; 49 class CodedOutputStream; 50 class ZeroCopyInputStream; 51 class ZeroCopyOutputStream; 52 } 53 54 // Interface to light weight protocol messages. 55 // 56 // This interface is implemented by all protocol message objects. Non-lite 57 // messages additionally implement the Message interface, which is a 58 // subclass of MessageLite. Use MessageLite instead when you only need 59 // the subset of features which it supports -- namely, nothing that uses 60 // descriptors or reflection. You can instruct the protocol compiler 61 // to generate classes which implement only MessageLite, not the full 62 // Message interface, by adding the following line to the .proto file: 63 // 64 // option optimize_for = LITE_RUNTIME; 65 // 66 // This is particularly useful on resource-constrained systems where 67 // the full protocol buffers runtime library is too big. 68 // 69 // Note that on non-constrained systems (e.g. servers) when you need 70 // to link in lots of protocol definitions, a better way to reduce 71 // total code footprint is to use optimize_for = CODE_SIZE. This 72 // will make the generated code smaller while still supporting all the 73 // same features (at the expense of speed). optimize_for = LITE_RUNTIME 74 // is best when you only have a small number of message types linked 75 // into your binary, in which case the size of the protocol buffers 76 // runtime itself is the biggest problem. 77 class LIBPROTOBUF_EXPORT MessageLite { 78 public: 79 inline MessageLite() {} 80 virtual ~MessageLite(); 81 82 // Basic Operations ------------------------------------------------ 83 84 // Get the name of this message type, e.g. "foo.bar.BazProto". 85 virtual string GetTypeName() const = 0; 86 87 // Construct a new instance of the same type. Ownership is passed to the 88 // caller. 89 virtual MessageLite* New() const = 0; 90 91 // Clear all fields of the message and set them to their default values. 92 // Clear() avoids freeing memory, assuming that any memory allocated 93 // to hold parts of the message will be needed again to hold the next 94 // message. If you actually want to free the memory used by a Message, 95 // you must delete it. 96 virtual void Clear() = 0; 97 98 // Quickly check if all required fields have values set. 99 virtual bool IsInitialized() const = 0; 100 101 // This is not implemented for Lite messages -- it just returns "(cannot 102 // determine missing fields for lite message)". However, it is implemented 103 // for full messages. See message.h. 104 virtual string InitializationErrorString() const; 105 106 // If |other| is the exact same class as this, calls MergeFrom(). Otherwise, 107 // results are undefined (probably crash). 108 virtual void CheckTypeAndMergeFrom(const MessageLite& other) = 0; 109 110 // Parsing --------------------------------------------------------- 111 // Methods for parsing in protocol buffer format. Most of these are 112 // just simple wrappers around MergeFromCodedStream(). Clear() will be called 113 // before merging the input. 114 115 // Fill the message with a protocol buffer parsed from the given input 116 // stream. Returns false on a read error or if the input is in the 117 // wrong format. 118 bool ParseFromCodedStream(io::CodedInputStream* input); 119 // Like ParseFromCodedStream(), but accepts messages that are missing 120 // required fields. 121 bool ParsePartialFromCodedStream(io::CodedInputStream* input); 122 // Read a protocol buffer from the given zero-copy input stream. If 123 // successful, the entire input will be consumed. 124 bool ParseFromZeroCopyStream(io::ZeroCopyInputStream* input); 125 // Like ParseFromZeroCopyStream(), but accepts messages that are missing 126 // required fields. 127 bool ParsePartialFromZeroCopyStream(io::ZeroCopyInputStream* input); 128 // Read a protocol buffer from the given zero-copy input stream, expecting 129 // the message to be exactly "size" bytes long. If successful, exactly 130 // this many bytes will have been consumed from the input. 131 bool ParseFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, int size); 132 // Like ParseFromBoundedZeroCopyStream(), but accepts messages that are 133 // missing required fields. 134 bool ParsePartialFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, 135 int size); 136 // Parse a protocol buffer contained in a string. 137 bool ParseFromString(const string& data); 138 // Like ParseFromString(), but accepts messages that are missing 139 // required fields. 140 bool ParsePartialFromString(const string& data); 141 // Parse a protocol buffer contained in an array of bytes. 142 bool ParseFromArray(const void* data, int size); 143 // Like ParseFromArray(), but accepts messages that are missing 144 // required fields. 145 bool ParsePartialFromArray(const void* data, int size); 146 147 148 // Reads a protocol buffer from the stream and merges it into this 149 // Message. Singular fields read from the input overwrite what is 150 // already in the Message and repeated fields are appended to those 151 // already present. 152 // 153 // It is the responsibility of the caller to call input->LastTagWas() 154 // (for groups) or input->ConsumedEntireMessage() (for non-groups) after 155 // this returns to verify that the message's end was delimited correctly. 156 // 157 // ParsefromCodedStream() is implemented as Clear() followed by 158 // MergeFromCodedStream(). 159 bool MergeFromCodedStream(io::CodedInputStream* input); 160 161 // Like MergeFromCodedStream(), but succeeds even if required fields are 162 // missing in the input. 163 // 164 // MergeFromCodedStream() is just implemented as MergePartialFromCodedStream() 165 // followed by IsInitialized(). 166 virtual bool MergePartialFromCodedStream(io::CodedInputStream* input) = 0; 167 168 169 // Serialization --------------------------------------------------- 170 // Methods for serializing in protocol buffer format. Most of these 171 // are just simple wrappers around ByteSize() and SerializeWithCachedSizes(). 172 173 // Write a protocol buffer of this message to the given output. Returns 174 // false on a write error. If the message is missing required fields, 175 // this may GOOGLE_CHECK-fail. 176 bool SerializeToCodedStream(io::CodedOutputStream* output) const; 177 // Like SerializeToCodedStream(), but allows missing required fields. 178 bool SerializePartialToCodedStream(io::CodedOutputStream* output) const; 179 // Write the message to the given zero-copy output stream. All required 180 // fields must be set. 181 bool SerializeToZeroCopyStream(io::ZeroCopyOutputStream* output) const; 182 // Like SerializeToZeroCopyStream(), but allows missing required fields. 183 bool SerializePartialToZeroCopyStream(io::ZeroCopyOutputStream* output) const; 184 // Serialize the message and store it in the given string. All required 185 // fields must be set. 186 bool SerializeToString(string* output) const; 187 // Like SerializeToString(), but allows missing required fields. 188 bool SerializePartialToString(string* output) const; 189 // Serialize the message and store it in the given byte array. All required 190 // fields must be set. 191 bool SerializeToArray(void* data, int size) const; 192 // Like SerializeToArray(), but allows missing required fields. 193 bool SerializePartialToArray(void* data, int size) const; 194 195 // Make a string encoding the message. Is equivalent to calling 196 // SerializeToString() on a string and using that. Returns the empty 197 // string if SerializeToString() would have returned an error. 198 // Note: If you intend to generate many such strings, you may 199 // reduce heap fragmentation by instead re-using the same string 200 // object with calls to SerializeToString(). 201 string SerializeAsString() const; 202 // Like SerializeAsString(), but allows missing required fields. 203 string SerializePartialAsString() const; 204 205 // Like SerializeToString(), but appends to the data to the string's existing 206 // contents. All required fields must be set. 207 bool AppendToString(string* output) const; 208 // Like AppendToString(), but allows missing required fields. 209 bool AppendPartialToString(string* output) const; 210 211 // Computes the serialized size of the message. This recursively calls 212 // ByteSize() on all embedded messages. If a subclass does not override 213 // this, it MUST override SetCachedSize(). 214 virtual int ByteSize() const = 0; 215 216 // Serializes the message without recomputing the size. The message must 217 // not have changed since the last call to ByteSize(); if it has, the results 218 // are undefined. 219 virtual void SerializeWithCachedSizes( 220 io::CodedOutputStream* output) const = 0; 221 222 // Like SerializeWithCachedSizes, but writes directly to *target, returning 223 // a pointer to the byte immediately after the last byte written. "target" 224 // must point at a byte array of at least ByteSize() bytes. 225 virtual uint8* SerializeWithCachedSizesToArray(uint8* target) const; 226 227 // Returns the result of the last call to ByteSize(). An embedded message's 228 // size is needed both to serialize it (because embedded messages are 229 // length-delimited) and to compute the outer message's size. Caching 230 // the size avoids computing it multiple times. 231 // 232 // ByteSize() does not automatically use the cached size when available 233 // because this would require invalidating it every time the message was 234 // modified, which would be too hard and expensive. (E.g. if a deeply-nested 235 // sub-message is changed, all of its parents' cached sizes would need to be 236 // invalidated, which is too much work for an otherwise inlined setter 237 // method.) 238 virtual int GetCachedSize() const = 0; 239 240 private: 241 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageLite); 242 }; 243 244 } // namespace protobuf 245 246 } // namespace google 247 #endif // GOOGLE_PROTOBUF_MESSAGE_LITE_H__ 248
