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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 // Author: kenton@google.com (Kenton Varda)
32 //  Based on original Protocol Buffers design by
33 //  Sanjay Ghemawat, Jeff Dean, and others.
34 //
35 // Defines an implementation of Message which can emulate types which are not
36 // known at compile-time.
37 
38 #ifndef GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__
39 #define GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__
40 
41 #include <algorithm>
42 #include <memory>
43 #include <vector>
44 
45 #include <google/protobuf/stubs/common.h>
46 #include <google/protobuf/message.h>
47 #include <google/protobuf/stubs/mutex.h>
48 #include <google/protobuf/reflection.h>
49 #include <google/protobuf/repeated_field.h>
50 
51 #ifdef SWIG
52 #error "You cannot SWIG proto headers"
53 #endif
54 
55 #include <google/protobuf/port_def.inc>
56 
57 namespace google {
58 namespace protobuf {
59 
60 // Defined in other files.
61 class Descriptor;      // descriptor.h
62 class DescriptorPool;  // descriptor.h
63 
64 // Constructs implementations of Message which can emulate types which are not
65 // known at compile-time.
66 //
67 // Sometimes you want to be able to manipulate protocol types that you don't
68 // know about at compile time.  It would be nice to be able to construct
69 // a Message object which implements the message type given by any arbitrary
70 // Descriptor.  DynamicMessage provides this.
71 //
72 // As it turns out, a DynamicMessage needs to construct extra
73 // information about its type in order to operate.  Most of this information
74 // can be shared between all DynamicMessages of the same type.  But, caching
75 // this information in some sort of global map would be a bad idea, since
76 // the cached information for a particular descriptor could outlive the
77 // descriptor itself.  To avoid this problem, DynamicMessageFactory
78 // encapsulates this "cache".  All DynamicMessages of the same type created
79 // from the same factory will share the same support data.  Any Descriptors
80 // used with a particular factory must outlive the factory.
81 class PROTOBUF_EXPORT DynamicMessageFactory : public MessageFactory {
82  public:
83   // Construct a DynamicMessageFactory that will search for extensions in
84   // the DescriptorPool in which the extendee is defined.
85   DynamicMessageFactory();
86 
87   // Construct a DynamicMessageFactory that will search for extensions in
88   // the given DescriptorPool.
89   //
90   // DEPRECATED:  Use CodedInputStream::SetExtensionRegistry() to tell the
91   //   parser to look for extensions in an alternate pool.  However, note that
92   //   this is almost never what you want to do.  Almost all users should use
93   //   the zero-arg constructor.
94   DynamicMessageFactory(const DescriptorPool* pool);
95 
96   ~DynamicMessageFactory();
97 
98   // Call this to tell the DynamicMessageFactory that if it is given a
99   // Descriptor d for which:
100   //   d->file()->pool() == DescriptorPool::generated_pool(),
101   // then it should delegate to MessageFactory::generated_factory() instead
102   // of constructing a dynamic implementation of the message.  In theory there
103   // is no down side to doing this, so it may become the default in the future.
SetDelegateToGeneratedFactory(bool enable)104   void SetDelegateToGeneratedFactory(bool enable) {
105     delegate_to_generated_factory_ = enable;
106   }
107 
108   // implements MessageFactory ---------------------------------------
109 
110   // Given a Descriptor, constructs the default (prototype) Message of that
111   // type.  You can then call that message's New() method to construct a
112   // mutable message of that type.
113   //
114   // Calling this method twice with the same Descriptor returns the same
115   // object.  The returned object remains property of the factory and will
116   // be destroyed when the factory is destroyed.  Also, any objects created
117   // by calling the prototype's New() method share some data with the
118   // prototype, so these must be destroyed before the DynamicMessageFactory
119   // is destroyed.
120   //
121   // The given descriptor must outlive the returned message, and hence must
122   // outlive the DynamicMessageFactory.
123   //
124   // The method is thread-safe.
125   const Message* GetPrototype(const Descriptor* type) override;
126 
127  private:
128   const DescriptorPool* pool_;
129   bool delegate_to_generated_factory_;
130 
131   // This struct just contains a hash_map.  We can't #include <hash_map> from
132   // this header due to hacks needed for hash_map portability in the open source
133   // release.  Namely, stubs/hash.h, which defines hash_map portably, is not a
134   // public header (for good reason), but dynamic_message.h is, and public
135   // headers may only #include other public headers.
136   struct PrototypeMap;
137   std::unique_ptr<PrototypeMap> prototypes_;
138   mutable internal::WrappedMutex prototypes_mutex_;
139 
140   friend class DynamicMessage;
141   const Message* GetPrototypeNoLock(const Descriptor* type);
142 
143   // Construct default oneof instance for reflection usage if oneof
144   // is defined.
145   static void ConstructDefaultOneofInstance(const Descriptor* type,
146                                             const uint32 offsets[],
147                                             void* default_oneof_instance);
148   // Delete default oneof instance. Called by ~DynamicMessageFactory.
149   static void DeleteDefaultOneofInstance(const Descriptor* type,
150                                          const uint32 offsets[],
151                                          const void* default_oneof_instance);
152 
153   GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DynamicMessageFactory);
154 };
155 
156 // Helper for computing a sorted list of map entries via reflection.
157 class PROTOBUF_EXPORT DynamicMapSorter {
158  public:
Sort(const Message & message,int map_size,const Reflection * reflection,const FieldDescriptor * field)159   static std::vector<const Message*> Sort(const Message& message, int map_size,
160                                           const Reflection* reflection,
161                                           const FieldDescriptor* field) {
162     std::vector<const Message*> result;
163     result.reserve(map_size);
164     RepeatedFieldRef<Message> map_field =
165         reflection->GetRepeatedFieldRef<Message>(message, field);
166     for (auto it = map_field.begin(); it != map_field.end(); ++it) {
167       result.push_back(&*it);
168     }
169     MapEntryMessageComparator comparator(field->message_type());
170     std::stable_sort(result.begin(), result.end(), comparator);
171     // Complain if the keys aren't in ascending order.
172 #ifndef NDEBUG
173     for (size_t j = 1; j < static_cast<size_t>(map_size); j++) {
174       if (!comparator(result[j - 1], result[j])) {
175         GOOGLE_LOG(ERROR) << (comparator(result[j], result[j - 1])
176                            ? "internal error in map key sorting"
177                            : "map keys are not unique");
178       }
179     }
180 #endif
181     return result;
182   }
183 
184  private:
185   class PROTOBUF_EXPORT MapEntryMessageComparator {
186    public:
MapEntryMessageComparator(const Descriptor * descriptor)187     explicit MapEntryMessageComparator(const Descriptor* descriptor)
188         : field_(descriptor->field(0)) {}
189 
operator()190     bool operator()(const Message* a, const Message* b) {
191       const Reflection* reflection = a->GetReflection();
192       switch (field_->cpp_type()) {
193         case FieldDescriptor::CPPTYPE_BOOL: {
194           bool first = reflection->GetBool(*a, field_);
195           bool second = reflection->GetBool(*b, field_);
196           return first < second;
197         }
198         case FieldDescriptor::CPPTYPE_INT32: {
199           int32 first = reflection->GetInt32(*a, field_);
200           int32 second = reflection->GetInt32(*b, field_);
201           return first < second;
202         }
203         case FieldDescriptor::CPPTYPE_INT64: {
204           int64 first = reflection->GetInt64(*a, field_);
205           int64 second = reflection->GetInt64(*b, field_);
206           return first < second;
207         }
208         case FieldDescriptor::CPPTYPE_UINT32: {
209           uint32 first = reflection->GetUInt32(*a, field_);
210           uint32 second = reflection->GetUInt32(*b, field_);
211           return first < second;
212         }
213         case FieldDescriptor::CPPTYPE_UINT64: {
214           uint64 first = reflection->GetUInt64(*a, field_);
215           uint64 second = reflection->GetUInt64(*b, field_);
216           return first < second;
217         }
218         case FieldDescriptor::CPPTYPE_STRING: {
219           std::string first = reflection->GetString(*a, field_);
220           std::string second = reflection->GetString(*b, field_);
221           return first < second;
222         }
223         default:
224           GOOGLE_LOG(DFATAL) << "Invalid key for map field.";
225           return true;
226       }
227     }
228 
229    private:
230     const FieldDescriptor* field_;
231   };
232 };
233 
234 }  // namespace protobuf
235 }  // namespace google
236 
237 #include <google/protobuf/port_undef.inc>
238 
239 #endif  // GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__
240