1 // Protocol Buffers - Google's data interchange format
2 // Copyright 2008 Google Inc. All rights reserved.
3 // http://code.google.com/p/protobuf/
5 // Redistribution and use in source and binary forms, with or without
6 // modification, are permitted provided that the following conditions are
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
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.
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.
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.
36 // Defines MessageLite, the abstract interface implemented by all (lite
37 // and non-lite) protocol message objects.
39 #ifndef GOOGLE_PROTOBUF_MESSAGE_LITE_H__
40 #define GOOGLE_PROTOBUF_MESSAGE_LITE_H__
42 #include <google/protobuf/stubs/common.h>
48 class CodedInputStream;
49 class CodedOutputStream;
50 class ZeroCopyInputStream;
51 class ZeroCopyOutputStream;
54 // Interface to light weight protocol messages.
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:
64 // option optimize_for = LITE_RUNTIME;
66 // This is particularly useful on resource-constrained systems where
67 // the full protocol buffers runtime library is too big.
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 {
79 inline MessageLite() {}
80 virtual ~MessageLite();
82 // Basic Operations ------------------------------------------------
84 // Get the name of this message type, e.g. "foo.bar.BazProto".
85 virtual string GetTypeName() const = 0;
87 // Construct a new instance of the same type. Ownership is passed to the
89 virtual MessageLite* New() const = 0;
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;
98 // Quickly check if all required fields have values set.
99 virtual bool IsInitialized() const = 0;
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;
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;
110 // Parsing ---------------------------------------------------------
111 // Methods for parsing in protocol buffer format. Most of these are
112 // just simple wrappers around MergeFromCodedStream().
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
117 bool ParseFromCodedStream(io::CodedInputStream* input);
118 // Like ParseFromCodedStream(), but accepts messages that are missing
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
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,
135 // Parse a protocol buffer contained in a string.
136 bool ParseFromString(const string& data);
137 // Like ParseFromString(), but accepts messages that are missing
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
144 bool ParsePartialFromArray(const void* data, int size);
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
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.
156 // ParsefromCodedStream() is implemented as Clear() followed by
157 // MergeFromCodedStream().
158 bool MergeFromCodedStream(io::CodedInputStream* input);
160 // Like MergeFromCodedStream(), but succeeds even if required fields are
161 // missing in the input.
163 // MergeFromCodedStream() is just implemented as MergePartialFromCodedStream()
164 // followed by IsInitialized().
165 virtual bool MergePartialFromCodedStream(io::CodedInputStream* input) = 0;
168 // Serialization ---------------------------------------------------
169 // Methods for serializing in protocol buffer format. Most of these
170 // are just simple wrappers around ByteSize() and SerializeWithCachedSizes().
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;
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;
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;
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;
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
218 virtual void SerializeWithCachedSizes(
219 io::CodedOutputStream* output) const = 0;
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;
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.
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
237 virtual int GetCachedSize() const = 0;
240 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageLite);
243 } // namespace protobuf
245 } // namespace google
246 #endif // GOOGLE_PROTOBUF_MESSAGE_LITE_H__