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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 
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 <climits>
43 #include <string>
44 
45 #include <google/protobuf/stubs/common.h>
46 #include <google/protobuf/stubs/logging.h>
47 #include <google/protobuf/arena.h>
48 #include <google/protobuf/stubs/once.h>
49 #include <google/protobuf/port.h>
50 #include <google/protobuf/stubs/strutil.h>
51 
52 
53 #include <google/protobuf/port_def.inc>
54 
55 #ifdef SWIG
56 #error "You cannot SWIG proto headers"
57 #endif
58 
59 namespace google {
60 namespace protobuf {
61 
62 template <typename T>
63 class RepeatedPtrField;
64 
65 namespace io {
66 
67 class CodedInputStream;
68 class CodedOutputStream;
69 class ZeroCopyInputStream;
70 class ZeroCopyOutputStream;
71 
72 }  // namespace io
73 namespace internal {
74 
75 // See parse_context.h for explanation
76 class ParseContext;
77 
78 class RepeatedPtrFieldBase;
79 class WireFormatLite;
80 class WeakFieldMap;
81 
82 // We compute sizes as size_t but cache them as int.  This function converts a
83 // computed size to a cached size.  Since we don't proceed with serialization
84 // if the total size was > INT_MAX, it is not important what this function
85 // returns for inputs > INT_MAX.  However this case should not error or
86 // GOOGLE_CHECK-fail, because the full size_t resolution is still returned from
87 // ByteSizeLong() and checked against INT_MAX; we can catch the overflow
88 // there.
ToCachedSize(size_t size)89 inline int ToCachedSize(size_t size) { return static_cast<int>(size); }
90 
91 // We mainly calculate sizes in terms of size_t, but some functions that
92 // compute sizes return "int".  These int sizes are expected to always be
93 // positive. This function is more efficient than casting an int to size_t
94 // directly on 64-bit platforms because it avoids making the compiler emit a
95 // sign extending instruction, which we don't want and don't want to pay for.
FromIntSize(int size)96 inline size_t FromIntSize(int size) {
97   // Convert to unsigned before widening so sign extension is not necessary.
98   return static_cast<unsigned int>(size);
99 }
100 
101 // For cases where a legacy function returns an integer size.  We GOOGLE_DCHECK()
102 // that the conversion will fit within an integer; if this is false then we
103 // are losing information.
ToIntSize(size_t size)104 inline int ToIntSize(size_t size) {
105   GOOGLE_DCHECK_LE(size, static_cast<size_t>(INT_MAX));
106   return static_cast<int>(size);
107 }
108 
109 // This type wraps a variable whose constructor and destructor are explicitly
110 // called. It is particularly useful for a global variable, without its
111 // constructor and destructor run on start and end of the program lifetime.
112 // This circumvents the initial construction order fiasco, while keeping
113 // the address of the empty string a compile time constant.
114 //
115 // Pay special attention to the initialization state of the object.
116 // 1. The object is "uninitialized" to begin with.
117 // 2. Call Construct() or DefaultConstruct() only if the object is
118 //    uninitialized. After the call, the object becomes "initialized".
119 // 3. Call get() and get_mutable() only if the object is initialized.
120 // 4. Call Destruct() only if the object is initialized.
121 //    After the call, the object becomes uninitialized.
122 template <typename T>
123 class ExplicitlyConstructed {
124  public:
DefaultConstruct()125   void DefaultConstruct() { new (&union_) T(); }
126 
127   template <typename... Args>
Construct(Args &&...args)128   void Construct(Args&&... args) {
129     new (&union_) T(std::forward<Args>(args)...);
130   }
131 
Destruct()132   void Destruct() { get_mutable()->~T(); }
133 
get()134   constexpr const T& get() const { return reinterpret_cast<const T&>(union_); }
get_mutable()135   T* get_mutable() { return reinterpret_cast<T*>(&union_); }
136 
137  private:
138   // Prefer c++14 aligned_storage, but for compatibility this will do.
139   union AlignedUnion {
140     char space[sizeof(T)];
141     int64 align_to_int64;
142     void* align_to_ptr;
143   } union_;
144 };
145 
146 // Default empty string object. Don't use this directly. Instead, call
147 // GetEmptyString() to get the reference.
148 PROTOBUF_EXPORT extern ExplicitlyConstructed<std::string>
149     fixed_address_empty_string;
150 
151 
GetEmptyStringAlreadyInited()152 PROTOBUF_EXPORT inline const std::string& GetEmptyStringAlreadyInited() {
153   return fixed_address_empty_string.get();
154 }
155 
156 PROTOBUF_EXPORT size_t StringSpaceUsedExcludingSelfLong(const std::string& str);
157 
158 }  // namespace internal
159 
160 // Interface to light weight protocol messages.
161 //
162 // This interface is implemented by all protocol message objects.  Non-lite
163 // messages additionally implement the Message interface, which is a
164 // subclass of MessageLite.  Use MessageLite instead when you only need
165 // the subset of features which it supports -- namely, nothing that uses
166 // descriptors or reflection.  You can instruct the protocol compiler
167 // to generate classes which implement only MessageLite, not the full
168 // Message interface, by adding the following line to the .proto file:
169 //
170 //   option optimize_for = LITE_RUNTIME;
171 //
172 // This is particularly useful on resource-constrained systems where
173 // the full protocol buffers runtime library is too big.
174 //
175 // Note that on non-constrained systems (e.g. servers) when you need
176 // to link in lots of protocol definitions, a better way to reduce
177 // total code footprint is to use optimize_for = CODE_SIZE.  This
178 // will make the generated code smaller while still supporting all the
179 // same features (at the expense of speed).  optimize_for = LITE_RUNTIME
180 // is best when you only have a small number of message types linked
181 // into your binary, in which case the size of the protocol buffers
182 // runtime itself is the biggest problem.
183 class PROTOBUF_EXPORT MessageLite {
184  public:
MessageLite()185   inline MessageLite() {}
~MessageLite()186   virtual ~MessageLite() {}
187 
188   // Basic Operations ------------------------------------------------
189 
190   // Get the name of this message type, e.g. "foo.bar.BazProto".
191   virtual std::string GetTypeName() const = 0;
192 
193   // Construct a new instance of the same type.  Ownership is passed to the
194   // caller.
195   virtual MessageLite* New() const = 0;
196 
197   // Construct a new instance on the arena. Ownership is passed to the caller
198   // if arena is a NULL. Default implementation for backwards compatibility.
199   virtual MessageLite* New(Arena* arena) const;
200 
201   // Get the arena, if any, associated with this message. Virtual method
202   // required for generic operations but most arena-related operations should
203   // use the GetArenaNoVirtual() generated-code method. Default implementation
204   // to reduce code size by avoiding the need for per-type implementations
205   // when types do not implement arena support.
GetArena()206   virtual Arena* GetArena() const { return NULL; }
207 
208   // Get a pointer that may be equal to this message's arena, or may not be.
209   // If the value returned by this method is equal to some arena pointer, then
210   // this message is on that arena; however, if this message is on some arena,
211   // this method may or may not return that arena's pointer. As a tradeoff,
212   // this method may be more efficient than GetArena(). The intent is to allow
213   // underlying representations that use e.g. tagged pointers to sometimes
214   // store the arena pointer directly, and sometimes in a more indirect way,
215   // and allow a fastpath comparison against the arena pointer when it's easy
216   // to obtain.
GetMaybeArenaPointer()217   virtual void* GetMaybeArenaPointer() const { return GetArena(); }
218 
219   // Clear all fields of the message and set them to their default values.
220   // Clear() avoids freeing memory, assuming that any memory allocated
221   // to hold parts of the message will be needed again to hold the next
222   // message.  If you actually want to free the memory used by a Message,
223   // you must delete it.
224   virtual void Clear() = 0;
225 
226   // Quickly check if all required fields have values set.
227   virtual bool IsInitialized() const = 0;
228 
229   // This is not implemented for Lite messages -- it just returns "(cannot
230   // determine missing fields for lite message)".  However, it is implemented
231   // for full messages.  See message.h.
232   virtual std::string InitializationErrorString() const;
233 
234   // If |other| is the exact same class as this, calls MergeFrom(). Otherwise,
235   // results are undefined (probably crash).
236   virtual void CheckTypeAndMergeFrom(const MessageLite& other) = 0;
237 
238   // These methods return a human-readable summary of the message. Note that
239   // since the MessageLite interface does not support reflection, there is very
240   // little information that these methods can provide. They are shadowed by
241   // methods of the same name on the Message interface which provide much more
242   // information. The methods here are intended primarily to facilitate code
243   // reuse for logic that needs to interoperate with both full and lite protos.
244   //
245   // The format of the returned string is subject to change, so please do not
246   // assume it will remain stable over time.
247   std::string DebugString() const;
ShortDebugString()248   std::string ShortDebugString() const { return DebugString(); }
249   // MessageLite::DebugString is already Utf8 Safe. This is to add compatibility
250   // with Message.
Utf8DebugString()251   std::string Utf8DebugString() const { return DebugString(); }
252 
253   // Parsing ---------------------------------------------------------
254   // Methods for parsing in protocol buffer format.  Most of these are
255   // just simple wrappers around MergeFromCodedStream().  Clear() will be
256   // called before merging the input.
257 
258   // Fill the message with a protocol buffer parsed from the given input
259   // stream. Returns false on a read error or if the input is in the wrong
260   // format.  A successful return does not indicate the entire input is
261   // consumed, ensure you call ConsumedEntireMessage() to check that if
262   // applicable.
263   bool ParseFromCodedStream(io::CodedInputStream* input);
264   // Like ParseFromCodedStream(), but accepts messages that are missing
265   // required fields.
266   bool ParsePartialFromCodedStream(io::CodedInputStream* input);
267   // Read a protocol buffer from the given zero-copy input stream.  If
268   // successful, the entire input will be consumed.
269   bool ParseFromZeroCopyStream(io::ZeroCopyInputStream* input);
270   // Like ParseFromZeroCopyStream(), but accepts messages that are missing
271   // required fields.
272   bool ParsePartialFromZeroCopyStream(io::ZeroCopyInputStream* input);
273   // Parse a protocol buffer from a file descriptor.  If successful, the entire
274   // input will be consumed.
275   bool ParseFromFileDescriptor(int file_descriptor);
276   // Like ParseFromFileDescriptor(), but accepts messages that are missing
277   // required fields.
278   bool ParsePartialFromFileDescriptor(int file_descriptor);
279   // Parse a protocol buffer from a C++ istream.  If successful, the entire
280   // input will be consumed.
281   bool ParseFromIstream(std::istream* input);
282   // Like ParseFromIstream(), but accepts messages that are missing
283   // required fields.
284   bool ParsePartialFromIstream(std::istream* input);
285   // Read a protocol buffer from the given zero-copy input stream, expecting
286   // the message to be exactly "size" bytes long.  If successful, exactly
287   // this many bytes will have been consumed from the input.
288   bool MergePartialFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input,
289                                              int size);
290   // Like ParseFromBoundedZeroCopyStream(), but accepts messages that are
291   // missing required fields.
292   bool MergeFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, int size);
293   bool ParseFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input, int size);
294   // Like ParseFromBoundedZeroCopyStream(), but accepts messages that are
295   // missing required fields.
296   bool ParsePartialFromBoundedZeroCopyStream(io::ZeroCopyInputStream* input,
297                                              int size);
298   // Parses a protocol buffer contained in a string. Returns true on success.
299   // This function takes a string in the (non-human-readable) binary wire
300   // format, matching the encoding output by MessageLite::SerializeToString().
301   // If you'd like to convert a human-readable string into a protocol buffer
302   // object, see google::protobuf::TextFormat::ParseFromString().
303   bool ParseFromString(const std::string& data);
304   // Like ParseFromString(), but accepts messages that are missing
305   // required fields.
306   bool ParsePartialFromString(const std::string& data);
307   // Parse a protocol buffer contained in an array of bytes.
308   bool ParseFromArray(const void* data, int size);
309   // Like ParseFromArray(), but accepts messages that are missing
310   // required fields.
311   bool ParsePartialFromArray(const void* data, int size);
312 
313 
314   // Reads a protocol buffer from the stream and merges it into this
315   // Message.  Singular fields read from the what is
316   // already in the Message and repeated fields are appended to those
317   // already present.
318   //
319   // It is the responsibility of the caller to call input->LastTagWas()
320   // (for groups) or input->ConsumedEntireMessage() (for non-groups) after
321   // this returns to verify that the message's end was delimited correctly.
322   //
323   // ParsefromCodedStream() is implemented as Clear() followed by
324   // MergeFromCodedStream().
325   bool MergeFromCodedStream(io::CodedInputStream* input);
326 
327   // Like MergeFromCodedStream(), but succeeds even if required fields are
328   // missing in the input.
329   //
330   // MergeFromCodedStream() is just implemented as MergePartialFromCodedStream()
331   // followed by IsInitialized().
332 #if GOOGLE_PROTOBUF_ENABLE_EXPERIMENTAL_PARSER
333   bool MergePartialFromCodedStream(io::CodedInputStream* input);
334 #else
335   virtual bool MergePartialFromCodedStream(io::CodedInputStream* input) = 0;
336 #endif  // GOOGLE_PROTOBUF_ENABLE_EXPERIMENTAL_PARSER
337 
338   // Merge a protocol buffer contained in a string.
339   bool MergeFromString(const std::string& data);
340 
341 
342   // Serialization ---------------------------------------------------
343   // Methods for serializing in protocol buffer format.  Most of these
344   // are just simple wrappers around ByteSize() and SerializeWithCachedSizes().
345 
346   // Write a protocol buffer of this message to the given output.  Returns
347   // false on a write error.  If the message is missing required fields,
348   // this may GOOGLE_CHECK-fail.
349   bool SerializeToCodedStream(io::CodedOutputStream* output) const;
350   // Like SerializeToCodedStream(), but allows missing required fields.
351   bool SerializePartialToCodedStream(io::CodedOutputStream* output) const;
352   // Write the message to the given zero-copy output stream.  All required
353   // fields must be set.
354   bool SerializeToZeroCopyStream(io::ZeroCopyOutputStream* output) const;
355   // Like SerializeToZeroCopyStream(), but allows missing required fields.
356   bool SerializePartialToZeroCopyStream(io::ZeroCopyOutputStream* output) const;
357   // Serialize the message and store it in the given string.  All required
358   // fields must be set.
359   bool SerializeToString(std::string* output) const;
360   // Like SerializeToString(), but allows missing required fields.
361   bool SerializePartialToString(std::string* output) const;
362   // Serialize the message and store it in the given byte array.  All required
363   // fields must be set.
364   bool SerializeToArray(void* data, int size) const;
365   // Like SerializeToArray(), but allows missing required fields.
366   bool SerializePartialToArray(void* data, int size) const;
367 
368   // Make a string encoding the message. Is equivalent to calling
369   // SerializeToString() on a string and using that.  Returns the empty
370   // string if SerializeToString() would have returned an error.
371   // Note: If you intend to generate many such strings, you may
372   // reduce heap fragmentation by instead re-using the same string
373   // object with calls to SerializeToString().
374   std::string SerializeAsString() const;
375   // Like SerializeAsString(), but allows missing required fields.
376   std::string SerializePartialAsString() const;
377 
378   // Serialize the message and write it to the given file descriptor.  All
379   // required fields must be set.
380   bool SerializeToFileDescriptor(int file_descriptor) const;
381   // Like SerializeToFileDescriptor(), but allows missing required fields.
382   bool SerializePartialToFileDescriptor(int file_descriptor) const;
383   // Serialize the message and write it to the given C++ ostream.  All
384   // required fields must be set.
385   bool SerializeToOstream(std::ostream* output) const;
386   // Like SerializeToOstream(), but allows missing required fields.
387   bool SerializePartialToOstream(std::ostream* output) const;
388 
389   // Like SerializeToString(), but appends to the data to the string's
390   // existing contents.  All required fields must be set.
391   bool AppendToString(std::string* output) const;
392   // Like AppendToString(), but allows missing required fields.
393   bool AppendPartialToString(std::string* output) const;
394 
395 
396   // Computes the serialized size of the message.  This recursively calls
397   // ByteSizeLong() on all embedded messages.
398   //
399   // ByteSizeLong() is generally linear in the number of fields defined for the
400   // proto.
401   virtual size_t ByteSizeLong() const = 0;
402 
403   // Legacy ByteSize() API.
404   PROTOBUF_DEPRECATED_MSG("Please use ByteSizeLong() instead")
ByteSize()405   int ByteSize() const { return internal::ToIntSize(ByteSizeLong()); }
406 
407   // Serializes the message without recomputing the size.  The message must not
408   // have changed since the last call to ByteSize(), and the value returned by
409   // ByteSize must be non-negative.  Otherwise the results are undefined.
410   virtual void SerializeWithCachedSizes(io::CodedOutputStream* output) const;
411 
412   // Functions below here are not part of the public interface.  It isn't
413   // enforced, but they should be treated as private, and will be private
414   // at some future time.  Unfortunately the implementation of the "friend"
415   // keyword in GCC is broken at the moment, but we expect it will be fixed.
416 
417   // Like SerializeWithCachedSizes, but writes directly to *target, returning
418   // a pointer to the byte immediately after the last byte written.  "target"
419   // must point at a byte array of at least ByteSize() bytes.  Whether to use
420   // deterministic serialization, e.g., maps in sorted order, is determined by
421   // CodedOutputStream::IsDefaultSerializationDeterministic().
422   virtual uint8* SerializeWithCachedSizesToArray(uint8* target) const;
423 
424   // Returns the result of the last call to ByteSize().  An embedded message's
425   // size is needed both to serialize it (because embedded messages are
426   // length-delimited) and to compute the outer message's size.  Caching
427   // the size avoids computing it multiple times.
428   //
429   // ByteSize() does not automatically use the cached size when available
430   // because this would require invalidating it every time the message was
431   // modified, which would be too hard and expensive.  (E.g. if a deeply-nested
432   // sub-message is changed, all of its parents' cached sizes would need to be
433   // invalidated, which is too much work for an otherwise inlined setter
434   // method.)
435   virtual int GetCachedSize() const = 0;
436 
437 #if GOOGLE_PROTOBUF_ENABLE_EXPERIMENTAL_PARSER
_InternalParse(const char * ptr,internal::ParseContext * ctx)438   virtual const char* _InternalParse(const char* ptr,
439                                      internal::ParseContext* ctx) {
440     return nullptr;
441   }
442 #endif  // GOOGLE_PROTOBUF_ENABLE_EXPERIMENTAL_PARSER
443 
444  protected:
445   // CastToBase allows generated code to cast a RepeatedPtrField<T> to
446   // RepeatedPtrFieldBase. We try to restrict access to RepeatedPtrFieldBase
447   // because it is an implementation detail that user code should not access
448   // directly.
449   template <typename T>
CastToBase(RepeatedPtrField<T> * repeated)450   static internal::RepeatedPtrFieldBase* CastToBase(
451       RepeatedPtrField<T>* repeated) {
452     return repeated;
453   }
454   template <typename T>
CastToBase(const RepeatedPtrField<T> & repeated)455   static const internal::RepeatedPtrFieldBase& CastToBase(
456       const RepeatedPtrField<T>& repeated) {
457     return repeated;
458   }
459 
460   template <typename T>
CreateMaybeMessage(Arena * arena)461   static T* CreateMaybeMessage(Arena* arena) {
462     return Arena::CreateMaybeMessage<T>(arena);
463   }
464 
465  public:
466   enum ParseFlags {
467     kMerge = 0,
468     kParse = 1,
469     kMergePartial = 2,
470     kParsePartial = 3,
471     kMergeWithAliasing = 4,
472     kParseWithAliasing = 5,
473     kMergePartialWithAliasing = 6,
474     kParsePartialWithAliasing = 7
475   };
476 
477   template <ParseFlags flags, typename T>
478   bool ParseFrom(const T& input);
479 
480  private:
481   // TODO(gerbens) make this a pure abstract function
InternalGetTable()482   virtual const void* InternalGetTable() const { return NULL; }
483 
484   // Fast path when conditions match (ie. non-deterministic)
485  public:
486   virtual uint8* InternalSerializeWithCachedSizesToArray(uint8* target) const;
487 
488  private:
489   friend class internal::WireFormatLite;
490   friend class Message;
491   friend class internal::WeakFieldMap;
492 
IsInitializedWithErrors()493   bool IsInitializedWithErrors() const {
494     if (IsInitialized()) return true;
495     LogInitializationErrorMessage();
496     return false;
497   }
498 
499   void LogInitializationErrorMessage() const;
500 
501   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(MessageLite);
502 };
503 
504 namespace internal {
505 
506 template <bool alias>
507 bool MergePartialFromImpl(StringPiece input, MessageLite* msg);
508 extern template bool MergePartialFromImpl<false>(StringPiece input,
509                                                  MessageLite* msg);
510 extern template bool MergePartialFromImpl<true>(StringPiece input,
511                                                 MessageLite* msg);
512 
513 template <bool alias>
514 bool MergePartialFromImpl(io::ZeroCopyInputStream* input, MessageLite* msg);
515 extern template bool MergePartialFromImpl<false>(io::ZeroCopyInputStream* input,
516                                                  MessageLite* msg);
517 extern template bool MergePartialFromImpl<true>(io::ZeroCopyInputStream* input,
518                                                 MessageLite* msg);
519 
520 struct BoundedZCIS {
521   io::ZeroCopyInputStream* zcis;
522   int limit;
523 };
524 
525 template <bool alias>
526 bool MergePartialFromImpl(BoundedZCIS input, MessageLite* msg);
527 extern template bool MergePartialFromImpl<false>(BoundedZCIS input,
528                                                  MessageLite* msg);
529 extern template bool MergePartialFromImpl<true>(BoundedZCIS input,
530                                                 MessageLite* msg);
531 
532 template <typename T>
533 struct SourceWrapper;
534 
535 template <bool alias, typename T>
MergePartialFromImpl(const SourceWrapper<T> & input,MessageLite * msg)536 bool MergePartialFromImpl(const SourceWrapper<T>& input, MessageLite* msg) {
537   return input.template MergePartialInto<alias>(msg);
538 }
539 
540 }  // namespace internal
541 
542 template <MessageLite::ParseFlags flags, typename T>
ParseFrom(const T & input)543 bool MessageLite::ParseFrom(const T& input) {
544   if (flags & kParse) Clear();
545   constexpr bool alias = flags & kMergeWithAliasing;
546   bool res = internal::MergePartialFromImpl<alias>(input, this);
547   return res && ((flags & kMergePartial) || IsInitializedWithErrors());
548 }
549 
550 }  // namespace protobuf
551 }  // namespace google
552 
553 #include <google/protobuf/port_undef.inc>
554 
555 #endif  // GOOGLE_PROTOBUF_MESSAGE_LITE_H__
556