1 // Protocol Buffers - Google's data interchange format 2 // Copyright 2008 Google Inc. All rights reserved. 3 // http://code.google.com/p/protobuf/ 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@google.com (Wink Saville), 32 // kenton@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: MessageLite()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(). 113 114 // Fill the message with a protocol buffer parsed from the given input 115 // stream. Returns false on a read error or if the input is in the 116 // wrong format. 117 bool ParseFromCodedStream(io::CodedInputStream* input); 118 // Like ParseFromCodedStream(), but accepts messages that are missing 119 // required fields. 120 bool ParsePartialFromCodedStream(io::CodedInputStream* input); 121 // Read a protocol buffer from the given zero-copy input stream. If 122 // successful, the entire input will be consumed. 123 bool ParseFromZeroCopyStream(io::ZeroCopyInputStream* input); 124 // Like ParseFromZeroCopyStream(), but accepts messages that are missing 125 // required fields. 126 bool ParsePartialFromZeroCopyStream(io::ZeroCopyInputStream* input); 127 // Read a protocol buffer from the given zero-copy input stream, expecting 128 // the message to be exactly "size" bytes long. If successful, exactly 129 // this many bytes will have been consumed from the input. 130 bool ParseFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, int size); 131 // Like ParseFromBoundedZeroCopyStream(), but accepts messages that are 132 // missing required fields. 133 bool ParsePartialFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, 134 int size); 135 // Parse a protocol buffer contained in a string. 136 bool ParseFromString(const string& data); 137 // Like ParseFromString(), but accepts messages that are missing 138 // required fields. 139 bool ParsePartialFromString(const string& data); 140 // Parse a protocol buffer contained in an array of bytes. 141 bool ParseFromArray(const void* data, int size); 142 // Like ParseFromArray(), but accepts messages that are missing 143 // required fields. 144 bool ParsePartialFromArray(const void* data, int size); 145 146 147 // Reads a protocol buffer from the stream and merges it into this 148 // Message. Singular fields read from the input overwrite what is 149 // already in the Message and repeated fields are appended to those 150 // already present. 151 // 152 // It is the responsibility of the caller to call input->LastTagWas() 153 // (for groups) or input->ConsumedEntireMessage() (for non-groups) after 154 // this returns to verify that the message's end was delimited correctly. 155 // 156 // ParsefromCodedStream() is implemented as Clear() followed by 157 // MergeFromCodedStream(). 158 bool MergeFromCodedStream(io::CodedInputStream* input); 159 160 // Like MergeFromCodedStream(), but succeeds even if required fields are 161 // missing in the input. 162 // 163 // MergeFromCodedStream() is just implemented as MergePartialFromCodedStream() 164 // followed by IsInitialized(). 165 virtual bool MergePartialFromCodedStream(io::CodedInputStream* input) = 0; 166 167 168 // Serialization --------------------------------------------------- 169 // Methods for serializing in protocol buffer format. Most of these 170 // are just simple wrappers around ByteSize() and SerializeWithCachedSizes(). 171 172 // Write a protocol buffer of this message to the given output. Returns 173 // false on a write error. If the message is missing required fields, 174 // this may GOOGLE_CHECK-fail. 175 bool SerializeToCodedStream(io::CodedOutputStream* output) const; 176 // Like SerializeToCodedStream(), but allows missing required fields. 177 bool SerializePartialToCodedStream(io::CodedOutputStream* output) const; 178 // Write the message to the given zero-copy output stream. All required 179 // fields must be set. 180 bool SerializeToZeroCopyStream(io::ZeroCopyOutputStream* output) const; 181 // Like SerializeToZeroCopyStream(), but allows missing required fields. 182 bool SerializePartialToZeroCopyStream(io::ZeroCopyOutputStream* output) const; 183 // Serialize the message and store it in the given string. All required 184 // fields must be set. 185 bool SerializeToString(string* output) const; 186 // Like SerializeToString(), but allows missing required fields. 187 bool SerializePartialToString(string* output) const; 188 // Serialize the message and store it in the given byte array. All required 189 // fields must be set. 190 bool SerializeToArray(void* data, int size) const; 191 // Like SerializeToArray(), but allows missing required fields. 192 bool SerializePartialToArray(void* data, int size) const; 193 194 // Make a string encoding the message. Is equivalent to calling 195 // SerializeToString() on a string and using that. Returns the empty 196 // string if SerializeToString() would have returned an error. 197 // Note: If you intend to generate many such strings, you may 198 // reduce heap fragmentation by instead re-using the same string 199 // object with calls to SerializeToString(). 200 string SerializeAsString() const; 201 // Like SerializeAsString(), but allows missing required fields. 202 string SerializePartialAsString() const; 203 204 // Like SerializeToString(), but appends to the data to the string's existing 205 // contents. All required fields must be set. 206 bool AppendToString(string* output) const; 207 // Like AppendToString(), but allows missing required fields. 208 bool AppendPartialToString(string* output) const; 209 210 // Computes the serialized size of the message. This recursively calls 211 // ByteSize() on all embedded messages. If a subclass does not override 212 // this, it MUST override SetCachedSize(). 213 virtual int ByteSize() const = 0; 214 215 // Serializes the message without recomputing the size. The message must 216 // not have changed since the last call to ByteSize(); if it has, the results 217 // are undefined. 218 virtual void SerializeWithCachedSizes( 219 io::CodedOutputStream* output) const = 0; 220 221 // Like SerializeWithCachedSizes, but writes directly to *target, returning 222 // a pointer to the byte immediately after the last byte written. "target" 223 // must point at a byte array of at least ByteSize() bytes. 224 virtual uint8* SerializeWithCachedSizesToArray(uint8* target) const; 225 226 // Returns the result of the last call to ByteSize(). An embedded message's 227 // size is needed both to serialize it (because embedded messages are 228 // length-delimited) and to compute the outer message's size. Caching 229 // the size avoids computing it multiple times. 230 // 231 // ByteSize() does not automatically use the cached size when available 232 // because this would require invalidating it every time the message was 233 // modified, which would be too hard and expensive. (E.g. if a deeply-nested 234 // sub-message is changed, all of its parents' cached sizes would need to be 235 // invalidated, which is too much work for an otherwise inlined setter 236 // method.) 237 virtual int GetCachedSize() const = 0; 238 239 private: 240 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageLite); 241 }; 242 243 } // namespace protobuf 244 245 } // namespace google 246 #endif // GOOGLE_PROTOBUF_MESSAGE_LITE_H__ 247