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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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