1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc. All rights reserved.
3// https://developers.google.com/protocol-buffers/
4//
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6// modification, are permitted provided that the following conditions are
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8//
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13// in the documentation and/or other materials provided with the
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18//
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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
42#include <algorithm>
43#include <memory>
44#include <unordered_map>
45#include <vector>
46
47#include <google/protobuf/stubs/common.h>
48#include <google/protobuf/stubs/mutex.h>
49#include <google/protobuf/message.h>
50#include <google/protobuf/reflection.h>
51#include <google/protobuf/repeated_field.h>
52
53#ifdef SWIG
54#error "You cannot SWIG proto headers"
55#endif
56
57// Must be included last.
58#include <google/protobuf/port_def.inc>
59
60namespace google {
61namespace protobuf {
62
63// Defined in other files.
64class Descriptor; // descriptor.h
65class DescriptorPool; // descriptor.h
66
67// Constructs implementations of Message which can emulate types which are not
68// known at compile-time.
69//
70// Sometimes you want to be able to manipulate protocol types that you don't
71// know about at compile time. It would be nice to be able to construct
72// a Message object which implements the message type given by any arbitrary
73// Descriptor. DynamicMessage provides this.
74//
75// As it turns out, a DynamicMessage needs to construct extra
76// information about its type in order to operate. Most of this information
77// can be shared between all DynamicMessages of the same type. But, caching
78// this information in some sort of global map would be a bad idea, since
79// the cached information for a particular descriptor could outlive the
80// descriptor itself. To avoid this problem, DynamicMessageFactory
81// encapsulates this "cache". All DynamicMessages of the same type created
82// from the same factory will share the same support data. Any Descriptors
83// used with a particular factory must outlive the factory.
84class PROTOBUF_EXPORT DynamicMessageFactory : public MessageFactory {
85 public:
86 // Construct a DynamicMessageFactory that will search for extensions in
87 // the DescriptorPool in which the extendee is defined.
88 DynamicMessageFactory();
89
90 // Construct a DynamicMessageFactory that will search for extensions in
91 // the given DescriptorPool.
92 //
93 // DEPRECATED: Use CodedInputStream::SetExtensionRegistry() to tell the
94 // parser to look for extensions in an alternate pool. However, note that
95 // this is almost never what you want to do. Almost all users should use
96 // the zero-arg constructor.
97 DynamicMessageFactory(const DescriptorPool* pool);
98
99 ~DynamicMessageFactory() override;
100
101 // Call this to tell the DynamicMessageFactory that if it is given a
102 // Descriptor d for which:
103 // d->file()->pool() == DescriptorPool::generated_pool(),
104 // then it should delegate to MessageFactory::generated_factory() instead
105 // of constructing a dynamic implementation of the message. In theory there
106 // is no down side to doing this, so it may become the default in the future.
107 void SetDelegateToGeneratedFactory(bool enable) {
108 delegate_to_generated_factory_ = enable;
109 }
110
111 // implements MessageFactory ---------------------------------------
112
113 // Given a Descriptor, constructs the default (prototype) Message of that
114 // type. You can then call that message's New() method to construct a
115 // mutable message of that type.
116 //
117 // Calling this method twice with the same Descriptor returns the same
118 // object. The returned object remains property of the factory and will
119 // be destroyed when the factory is destroyed. Also, any objects created
120 // by calling the prototype's New() method share some data with the
121 // prototype, so these must be destroyed before the DynamicMessageFactory
122 // is destroyed.
123 //
124 // The given descriptor must outlive the returned message, and hence must
125 // outlive the DynamicMessageFactory.
126 //
127 // The method is thread-safe.
128 const Message* GetPrototype(const Descriptor* type) override;
129
130 private:
131 const DescriptorPool* pool_;
132 bool delegate_to_generated_factory_;
133
134 struct TypeInfo;
135 std::unordered_map<const Descriptor*, const TypeInfo*> prototypes_;
136 mutable internal::WrappedMutex prototypes_mutex_;
137
138 friend class DynamicMessage;
139 const Message* GetPrototypeNoLock(const Descriptor* type);
140
141 GOOGLE_DISALLOW_EVIL_CONSTRUCTORS(DynamicMessageFactory);
142};
143
144// Helper for computing a sorted list of map entries via reflection.
145class PROTOBUF_EXPORT DynamicMapSorter {
146 public:
147 static std::vector<const Message*> Sort(const Message& message, int map_size,
148 const Reflection* reflection,
149 const FieldDescriptor* field) {
150 std::vector<const Message*> result;
151 result.reserve(n: map_size);
152 RepeatedFieldRef<Message> map_field =
153 reflection->GetRepeatedFieldRef<Message>(message, field);
154 for (auto it = map_field.begin(); it != map_field.end(); ++it) {
155 result.push_back(x: &*it);
156 }
157 MapEntryMessageComparator comparator(field->message_type());
158 std::stable_sort(first: result.begin(), last: result.end(), comp: comparator);
159 // Complain if the keys aren't in ascending order.
160#ifndef NDEBUG
161 for (size_t j = 1; j < static_cast<size_t>(map_size); j++) {
162 if (!comparator(result[j - 1], result[j])) {
163 GOOGLE_LOG(ERROR) << (comparator(result[j], result[j - 1])
164 ? "internal error in map key sorting"
165 : "map keys are not unique");
166 }
167 }
168#endif
169 return result;
170 }
171
172 private:
173 class PROTOBUF_EXPORT MapEntryMessageComparator {
174 public:
175 explicit MapEntryMessageComparator(const Descriptor* descriptor)
176 : field_(descriptor->field(index: 0)) {}
177
178 bool operator()(const Message* a, const Message* b) {
179 const Reflection* reflection = a->GetReflection();
180 switch (field_->cpp_type()) {
181 case FieldDescriptor::CPPTYPE_BOOL: {
182 bool first = reflection->GetBool(message: *a, field: field_);
183 bool second = reflection->GetBool(message: *b, field: field_);
184 return first < second;
185 }
186 case FieldDescriptor::CPPTYPE_INT32: {
187 int32_t first = reflection->GetInt32(message: *a, field: field_);
188 int32_t second = reflection->GetInt32(message: *b, field: field_);
189 return first < second;
190 }
191 case FieldDescriptor::CPPTYPE_INT64: {
192 int64_t first = reflection->GetInt64(message: *a, field: field_);
193 int64_t second = reflection->GetInt64(message: *b, field: field_);
194 return first < second;
195 }
196 case FieldDescriptor::CPPTYPE_UINT32: {
197 uint32_t first = reflection->GetUInt32(message: *a, field: field_);
198 uint32_t second = reflection->GetUInt32(message: *b, field: field_);
199 return first < second;
200 }
201 case FieldDescriptor::CPPTYPE_UINT64: {
202 uint64_t first = reflection->GetUInt64(message: *a, field: field_);
203 uint64_t second = reflection->GetUInt64(message: *b, field: field_);
204 return first < second;
205 }
206 case FieldDescriptor::CPPTYPE_STRING: {
207 std::string first = reflection->GetString(message: *a, field: field_);
208 std::string second = reflection->GetString(message: *b, field: field_);
209 return first < second;
210 }
211 default:
212 GOOGLE_LOG(DFATAL) << "Invalid key for map field.";
213 return true;
214 }
215 }
216
217 private:
218 const FieldDescriptor* field_;
219 };
220};
221
222} // namespace protobuf
223} // namespace google
224
225#include <google/protobuf/port_undef.inc>
226
227#endif // GOOGLE_PROTOBUF_DYNAMIC_MESSAGE_H__
228