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1 // Copyright 2013 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 // | |
5 // The original source code is from: | |
6 // http://src.chromium.org/viewvc/chrome/trunk/src/base/stl_util.h?revision=2210
67 | |
7 | |
8 // Derived from google3/util/gtl/stl_util.h | |
9 | |
10 #ifndef I18N_ADDRESSINPUT_UTIL_STL_UTIL_H_ | |
11 #define I18N_ADDRESSINPUT_UTIL_STL_UTIL_H_ | |
12 | |
13 #include <algorithm> | |
14 #include <cassert> | |
15 #include <functional> | |
16 #include <iterator> | |
17 #include <string> | |
18 #include <vector> | |
19 | |
20 // Clears internal memory of an STL object. | |
21 // STL clear()/reserve(0) does not always free internal memory allocated | |
22 // This function uses swap/destructor to ensure the internal memory is freed. | |
23 template<class T> | |
24 void STLClearObject(T* obj) { | |
25 T tmp; | |
26 tmp.swap(*obj); | |
27 // Sometimes "T tmp" allocates objects with memory (arena implementation?). | |
28 // Hence using additional reserve(0) even if it doesn't always work. | |
29 obj->reserve(0); | |
30 } | |
31 | |
32 // For a range within a container of pointers, calls delete (non-array version) | |
33 // on these pointers. | |
34 // NOTE: for these three functions, we could just implement a DeleteObject | |
35 // functor and then call for_each() on the range and functor, but this | |
36 // requires us to pull in all of algorithm.h, which seems expensive. | |
37 // For hash_[multi]set, it is important that this deletes behind the iterator | |
38 // because the hash_set may call the hash function on the iterator when it is | |
39 // advanced, which could result in the hash function trying to deference a | |
40 // stale pointer. | |
41 template <class ForwardIterator> | |
42 void STLDeleteContainerPointers(ForwardIterator begin, ForwardIterator end) { | |
43 while (begin != end) { | |
44 ForwardIterator temp = begin; | |
45 ++begin; | |
46 delete *temp; | |
47 } | |
48 } | |
49 | |
50 // For a range within a container of pairs, calls delete (non-array version) on | |
51 // BOTH items in the pairs. | |
52 // NOTE: Like STLDeleteContainerPointers, it is important that this deletes | |
53 // behind the iterator because if both the key and value are deleted, the | |
54 // container may call the hash function on the iterator when it is advanced, | |
55 // which could result in the hash function trying to dereference a stale | |
56 // pointer. | |
57 template <class ForwardIterator> | |
58 void STLDeleteContainerPairPointers(ForwardIterator begin, | |
59 ForwardIterator end) { | |
60 while (begin != end) { | |
61 ForwardIterator temp = begin; | |
62 ++begin; | |
63 delete temp->first; | |
64 delete temp->second; | |
65 } | |
66 } | |
67 | |
68 // For a range within a container of pairs, calls delete (non-array version) on | |
69 // the FIRST item in the pairs. | |
70 // NOTE: Like STLDeleteContainerPointers, deleting behind the iterator. | |
71 template <class ForwardIterator> | |
72 void STLDeleteContainerPairFirstPointers(ForwardIterator begin, | |
73 ForwardIterator end) { | |
74 while (begin != end) { | |
75 ForwardIterator temp = begin; | |
76 ++begin; | |
77 delete temp->first; | |
78 } | |
79 } | |
80 | |
81 // For a range within a container of pairs, calls delete. | |
82 // NOTE: Like STLDeleteContainerPointers, deleting behind the iterator. | |
83 // Deleting the value does not always invalidate the iterator, but it may | |
84 // do so if the key is a pointer into the value object. | |
85 template <class ForwardIterator> | |
86 void STLDeleteContainerPairSecondPointers(ForwardIterator begin, | |
87 ForwardIterator end) { | |
88 while (begin != end) { | |
89 ForwardIterator temp = begin; | |
90 ++begin; | |
91 delete temp->second; | |
92 } | |
93 } | |
94 | |
95 // To treat a possibly-empty vector as an array, use these functions. | |
96 // If you know the array will never be empty, you can use &*v.begin() | |
97 // directly, but that is undefined behaviour if |v| is empty. | |
98 template<typename T> | |
99 inline T* vector_as_array(std::vector<T>* v) { | |
100 return v->empty() ? NULL : &*v->begin(); | |
101 } | |
102 | |
103 template<typename T> | |
104 inline const T* vector_as_array(const std::vector<T>* v) { | |
105 return v->empty() ? NULL : &*v->begin(); | |
106 } | |
107 | |
108 // Return a mutable char* pointing to a string's internal buffer, | |
109 // which may not be null-terminated. Writing through this pointer will | |
110 // modify the string. | |
111 // | |
112 // string_as_array(&str)[i] is valid for 0 <= i < str.size() until the | |
113 // next call to a string method that invalidates iterators. | |
114 // | |
115 // As of 2006-04, there is no standard-blessed way of getting a | |
116 // mutable reference to a string's internal buffer. However, issue 530 | |
117 // (http://www.open-std.org/JTC1/SC22/WG21/docs/lwg-active.html#530) | |
118 // proposes this as the method. According to Matt Austern, this should | |
119 // already work on all current implementations. | |
120 inline char* string_as_array(std::string* str) { | |
121 // DO NOT USE const_cast<char*>(str->data()) | |
122 return str->empty() ? NULL : &*str->begin(); | |
123 } | |
124 | |
125 // The following functions are useful for cleaning up STL containers whose | |
126 // elements point to allocated memory. | |
127 | |
128 // STLDeleteElements() deletes all the elements in an STL container and clears | |
129 // the container. This function is suitable for use with a vector, set, | |
130 // hash_set, or any other STL container which defines sensible begin(), end(), | |
131 // and clear() methods. | |
132 // | |
133 // If container is NULL, this function is a no-op. | |
134 // | |
135 // As an alternative to calling STLDeleteElements() directly, consider | |
136 // STLElementDeleter (defined below), which ensures that your container's | |
137 // elements are deleted when the STLElementDeleter goes out of scope. | |
138 template <class T> | |
139 void STLDeleteElements(T* container) { | |
140 if (!container) | |
141 return; | |
142 STLDeleteContainerPointers(container->begin(), container->end()); | |
143 container->clear(); | |
144 } | |
145 | |
146 // Given an STL container consisting of (key, value) pairs, STLDeleteValues | |
147 // deletes all the "value" components and clears the container. Does nothing | |
148 // in the case it's given a NULL pointer. | |
149 template <class T> | |
150 void STLDeleteValues(T* container) { | |
151 if (!container) | |
152 return; | |
153 for (typename T::iterator i(container->begin()); i != container->end(); ++i) | |
154 delete i->second; | |
155 container->clear(); | |
156 } | |
157 | |
158 | |
159 // The following classes provide a convenient way to delete all elements or | |
160 // values from STL containers when they goes out of scope. This greatly | |
161 // simplifies code that creates temporary objects and has multiple return | |
162 // statements. Example: | |
163 // | |
164 // vector<MyProto *> tmp_proto; | |
165 // STLElementDeleter<vector<MyProto *> > d(&tmp_proto); | |
166 // if (...) return false; | |
167 // ... | |
168 // return success; | |
169 | |
170 // Given a pointer to an STL container this class will delete all the element | |
171 // pointers when it goes out of scope. | |
172 template<class T> | |
173 class STLElementDeleter { | |
174 public: | |
175 STLElementDeleter<T>(T* container) : container_(container) {} | |
176 ~STLElementDeleter<T>() { STLDeleteElements(container_); } | |
177 | |
178 private: | |
179 T* container_; | |
180 }; | |
181 | |
182 // Given a pointer to an STL container this class will delete all the value | |
183 // pointers when it goes out of scope. | |
184 template<class T> | |
185 class STLValueDeleter { | |
186 public: | |
187 STLValueDeleter<T>(T* container) : container_(container) {} | |
188 ~STLValueDeleter<T>() { STLDeleteValues(container_); } | |
189 | |
190 private: | |
191 T* container_; | |
192 }; | |
193 | |
194 // Test to see if a set, map, hash_set or hash_map contains a particular key. | |
195 // Returns true if the key is in the collection. | |
196 template <typename Collection, typename Key> | |
197 bool ContainsKey(const Collection& collection, const Key& key) { | |
198 return collection.find(key) != collection.end(); | |
199 } | |
200 | |
201 namespace i18n { | |
202 namespace addressinput { | |
203 | |
204 // Returns true if the container is sorted. | |
205 template <typename Container> | |
206 bool STLIsSorted(const Container& cont) { | |
207 return std::adjacent_find(cont.begin(), cont.end(), | |
208 std::greater<typename Container::value_type>()) | |
209 == cont.end(); | |
210 } | |
211 | |
212 // Returns a new ResultType containing the difference of two sorted containers. | |
213 template <typename ResultType, typename Arg1, typename Arg2> | |
214 ResultType STLSetDifference(const Arg1& a1, const Arg2& a2) { | |
215 assert(STLIsSorted(a1)); | |
216 assert(STLIsSorted(a2)); | |
217 ResultType difference; | |
218 std::set_difference(a1.begin(), a1.end(), | |
219 a2.begin(), a2.end(), | |
220 std::inserter(difference, difference.end())); | |
221 return difference; | |
222 } | |
223 | |
224 } // namespace addressinput | |
225 } // namespace i18n | |
226 | |
227 #endif // I18N_ADDRESSINPUT_UTIL_STL_UTIL_H_ | |
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