1 /*
2 * Copyright 2017 Google Inc. All rights reserved.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #ifndef FLATBUFFERS_STL_EMULATION_H_
18 #define FLATBUFFERS_STL_EMULATION_H_
19
20 // clang-format off
21
22 #include <string>
23 #include <type_traits>
24 #include <vector>
25 #include <memory>
26 #include <limits>
27
28 #if defined(_STLPORT_VERSION) && !defined(FLATBUFFERS_CPP98_STL)
29 #define FLATBUFFERS_CPP98_STL
30 #endif // defined(_STLPORT_VERSION) && !defined(FLATBUFFERS_CPP98_STL)
31
32 #if defined(FLATBUFFERS_CPP98_STL)
33 #include <cctype>
34 #endif // defined(FLATBUFFERS_CPP98_STL)
35
36 // Check if we can use template aliases
37 // Not possible if Microsoft Compiler before 2012
38 // Possible is the language feature __cpp_alias_templates is defined well
39 // Or possible if the C++ std is C+11 or newer
40 #if (defined(_MSC_VER) && _MSC_VER > 1700 /* MSVC2012 */) \
41 || (defined(__cpp_alias_templates) && __cpp_alias_templates >= 200704) \
42 || (defined(__cplusplus) && __cplusplus >= 201103L)
43 #define FLATBUFFERS_TEMPLATES_ALIASES
44 #endif
45
46 // This header provides backwards compatibility for C++98 STLs like stlport.
47 namespace flatbuffers {
48
49 // Retrieve ::back() from a string in a way that is compatible with pre C++11
50 // STLs (e.g stlport).
string_back(std::string & value)51 inline char& string_back(std::string &value) {
52 return value[value.length() - 1];
53 }
54
string_back(const std::string & value)55 inline char string_back(const std::string &value) {
56 return value[value.length() - 1];
57 }
58
59 // Helper method that retrieves ::data() from a vector in a way that is
60 // compatible with pre C++11 STLs (e.g stlport).
vector_data(std::vector<T> & vector)61 template <typename T> inline T *vector_data(std::vector<T> &vector) {
62 // In some debug environments, operator[] does bounds checking, so &vector[0]
63 // can't be used.
64 return vector.empty() ? nullptr : &vector[0];
65 }
66
vector_data(const std::vector<T> & vector)67 template <typename T> inline const T *vector_data(
68 const std::vector<T> &vector) {
69 return vector.empty() ? nullptr : &vector[0];
70 }
71
72 template <typename T, typename V>
vector_emplace_back(std::vector<T> * vector,V && data)73 inline void vector_emplace_back(std::vector<T> *vector, V &&data) {
74 #if defined(FLATBUFFERS_CPP98_STL)
75 vector->push_back(data);
76 #else
77 vector->emplace_back(std::forward<V>(data));
78 #endif // defined(FLATBUFFERS_CPP98_STL)
79 }
80
81 #ifndef FLATBUFFERS_CPP98_STL
82 #if defined(FLATBUFFERS_TEMPLATES_ALIASES)
83 template <typename T>
84 using numeric_limits = std::numeric_limits<T>;
85 #else
86 template <typename T> class numeric_limits :
87 public std::numeric_limits<T> {};
88 #endif // defined(FLATBUFFERS_TEMPLATES_ALIASES)
89 #else
90 template <typename T> class numeric_limits :
91 public std::numeric_limits<T> {
92 public:
93 // Android NDK fix.
lowest()94 static T lowest() {
95 return std::numeric_limits<T>::min();
96 }
97 };
98
99 template <> class numeric_limits<float> :
100 public std::numeric_limits<float> {
101 public:
lowest()102 static float lowest() { return -FLT_MAX; }
103 };
104
105 template <> class numeric_limits<double> :
106 public std::numeric_limits<double> {
107 public:
lowest()108 static double lowest() { return -DBL_MAX; }
109 };
110
111 template <> class numeric_limits<unsigned long long> {
112 public:
min()113 static unsigned long long min() { return 0ULL; }
max()114 static unsigned long long max() { return ~0ULL; }
lowest()115 static unsigned long long lowest() {
116 return numeric_limits<unsigned long long>::min();
117 }
118 };
119
120 template <> class numeric_limits<long long> {
121 public:
min()122 static long long min() {
123 return static_cast<long long>(1ULL << ((sizeof(long long) << 3) - 1));
124 }
max()125 static long long max() {
126 return static_cast<long long>(
127 (1ULL << ((sizeof(long long) << 3) - 1)) - 1);
128 }
lowest()129 static long long lowest() {
130 return numeric_limits<long long>::min();
131 }
132 };
133 #endif // FLATBUFFERS_CPP98_STL
134
135 #if defined(FLATBUFFERS_TEMPLATES_ALIASES)
136 #ifndef FLATBUFFERS_CPP98_STL
137 template <typename T> using is_scalar = std::is_scalar<T>;
138 template <typename T, typename U> using is_same = std::is_same<T,U>;
139 template <typename T> using is_floating_point = std::is_floating_point<T>;
140 template <typename T> using is_unsigned = std::is_unsigned<T>;
141 template <typename T> using is_enum = std::is_enum<T>;
142 template <typename T> using make_unsigned = std::make_unsigned<T>;
143 template<bool B, class T, class F>
144 using conditional = std::conditional<B, T, F>;
145 template<class T, T v>
146 using integral_constant = std::integral_constant<T, v>;
147 #else
148 // Map C++ TR1 templates defined by stlport.
149 template <typename T> using is_scalar = std::tr1::is_scalar<T>;
150 template <typename T, typename U> using is_same = std::tr1::is_same<T,U>;
151 template <typename T> using is_floating_point =
152 std::tr1::is_floating_point<T>;
153 template <typename T> using is_unsigned = std::tr1::is_unsigned<T>;
154 template <typename T> using is_enum = std::tr1::is_enum<T>;
155 // Android NDK doesn't have std::make_unsigned or std::tr1::make_unsigned.
156 template<typename T> struct make_unsigned {
157 static_assert(is_unsigned<T>::value, "Specialization not implemented!");
158 using type = T;
159 };
160 template<> struct make_unsigned<char> { using type = unsigned char; };
161 template<> struct make_unsigned<short> { using type = unsigned short; };
162 template<> struct make_unsigned<int> { using type = unsigned int; };
163 template<> struct make_unsigned<long> { using type = unsigned long; };
164 template<>
165 struct make_unsigned<long long> { using type = unsigned long long; };
166 template<bool B, class T, class F>
167 using conditional = std::tr1::conditional<B, T, F>;
168 template<class T, T v>
169 using integral_constant = std::tr1::integral_constant<T, v>;
170 #endif // !FLATBUFFERS_CPP98_STL
171 #else
172 // MSVC 2010 doesn't support C++11 aliases.
173 template <typename T> struct is_scalar : public std::is_scalar<T> {};
174 template <typename T, typename U> struct is_same : public std::is_same<T,U> {};
175 template <typename T> struct is_floating_point :
176 public std::is_floating_point<T> {};
177 template <typename T> struct is_unsigned : public std::is_unsigned<T> {};
178 template <typename T> struct is_enum : public std::is_enum<T> {};
179 template <typename T> struct make_unsigned : public std::make_unsigned<T> {};
180 template<bool B, class T, class F>
181 struct conditional : public std::conditional<B, T, F> {};
182 template<class T, T v>
183 struct integral_constant : public std::integral_constant<T, v> {};
184 #endif // defined(FLATBUFFERS_TEMPLATES_ALIASES)
185
186 #ifndef FLATBUFFERS_CPP98_STL
187 #if defined(FLATBUFFERS_TEMPLATES_ALIASES)
188 template <class T> using unique_ptr = std::unique_ptr<T>;
189 #else
190 // MSVC 2010 doesn't support C++11 aliases.
191 // We're manually "aliasing" the class here as we want to bring unique_ptr
192 // into the flatbuffers namespace. We have unique_ptr in the flatbuffers
193 // namespace we have a completely independent implemenation (see below)
194 // for C++98 STL implementations.
195 template <class T> class unique_ptr : public std::unique_ptr<T> {
196 public:
197 unique_ptr() {}
198 explicit unique_ptr(T* p) : std::unique_ptr<T>(p) {}
199 unique_ptr(std::unique_ptr<T>&& u) { *this = std::move(u); }
200 unique_ptr(unique_ptr&& u) { *this = std::move(u); }
201 unique_ptr& operator=(std::unique_ptr<T>&& u) {
202 std::unique_ptr<T>::reset(u.release());
203 return *this;
204 }
205 unique_ptr& operator=(unique_ptr&& u) {
206 std::unique_ptr<T>::reset(u.release());
207 return *this;
208 }
209 unique_ptr& operator=(T* p) {
210 return std::unique_ptr<T>::operator=(p);
211 }
212 };
213 #endif // defined(FLATBUFFERS_TEMPLATES_ALIASES)
214 #else
215 // Very limited implementation of unique_ptr.
216 // This is provided simply to allow the C++ code generated from the default
217 // settings to function in C++98 environments with no modifications.
218 template <class T> class unique_ptr {
219 public:
220 typedef T element_type;
221
222 unique_ptr() : ptr_(nullptr) {}
223 explicit unique_ptr(T* p) : ptr_(p) {}
224 unique_ptr(unique_ptr&& u) : ptr_(nullptr) { reset(u.release()); }
225 unique_ptr(const unique_ptr& u) : ptr_(nullptr) {
226 reset(const_cast<unique_ptr*>(&u)->release());
227 }
228 ~unique_ptr() { reset(); }
229
230 unique_ptr& operator=(const unique_ptr& u) {
231 reset(const_cast<unique_ptr*>(&u)->release());
232 return *this;
233 }
234
235 unique_ptr& operator=(unique_ptr&& u) {
236 reset(u.release());
237 return *this;
238 }
239
240 unique_ptr& operator=(T* p) {
241 reset(p);
242 return *this;
243 }
244
245 const T& operator*() const { return *ptr_; }
246 T* operator->() const { return ptr_; }
247 T* get() const noexcept { return ptr_; }
248 explicit operator bool() const { return ptr_ != nullptr; }
249
250 // modifiers
251 T* release() {
252 T* value = ptr_;
253 ptr_ = nullptr;
254 return value;
255 }
256
257 void reset(T* p = nullptr) {
258 T* value = ptr_;
259 ptr_ = p;
260 if (value) delete value;
261 }
262
263 void swap(unique_ptr& u) {
264 T* temp_ptr = ptr_;
265 ptr_ = u.ptr_;
266 u.ptr_ = temp_ptr;
267 }
268
269 private:
270 T* ptr_;
271 };
272
273 template <class T> bool operator==(const unique_ptr<T>& x,
274 const unique_ptr<T>& y) {
275 return x.get() == y.get();
276 }
277
278 template <class T, class D> bool operator==(const unique_ptr<T>& x,
279 const D* y) {
280 return static_cast<D*>(x.get()) == y;
281 }
282
283 template <class T> bool operator==(const unique_ptr<T>& x, intptr_t y) {
284 return reinterpret_cast<intptr_t>(x.get()) == y;
285 }
286
287 template <class T> bool operator!=(const unique_ptr<T>& x, decltype(nullptr)) {
288 return !!x;
289 }
290
291 template <class T> bool operator!=(decltype(nullptr), const unique_ptr<T>& x) {
292 return !!x;
293 }
294
295 template <class T> bool operator==(const unique_ptr<T>& x, decltype(nullptr)) {
296 return !x;
297 }
298
299 template <class T> bool operator==(decltype(nullptr), const unique_ptr<T>& x) {
300 return !x;
301 }
302
303 #endif // !FLATBUFFERS_CPP98_STL
304
305 } // namespace flatbuffers
306
307 #endif // FLATBUFFERS_STL_EMULATION_H_
308