message_lite.h 11 KB

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