ui/base/l10n/l10n_util_collator.h

   1 // Copyright (c) 2011 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 #ifndef UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
   6 #define UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
   7
   8 #include <algorithm>
   9 #include <functional>
  10 #include <string>
  11 #include <vector>
  12
  13 #include "base/i18n/string_compare.h"
  14 #include "base/memory/scoped_ptr.h"
  15 #include "third_party/icu/source/i18n/unicode/coll.h"
  16 #include "ui/base/ui_base_export.h"
  17
  18 namespace l10n_util {
  19
  20 // Used by SortStringsUsingMethod. Invokes a method on the objects passed to
  21 // operator (), comparing the string results using a collator.
  22 template <class T, class Method>
  23 class StringMethodComparatorWithCollator
  24     : public std::binary_function<const base::string16&,
  25                                   const base::string16&,
  26                                   bool> {
  27  public:
  28   StringMethodComparatorWithCollator(icu::Collator* collator, Method method)
  29       : collator_(collator),
  30         method_(method) { }
  31
  32   // Returns true if lhs preceeds rhs.
  33   bool operator() (T* lhs_t, T* rhs_t) {
  34     return base::i18n::CompareString16WithCollator(collator_,
  35         (lhs_t->*method_)(), (rhs_t->*method_)()) == UCOL_LESS;
  36   }
  37
  38  private:
  39   icu::Collator* collator_;
  40   Method method_;
  41 };
  42
  43 // Used by SortStringsUsingMethod. Invokes a method on the objects passed to
  44 // operator (), comparing the string results using <.
  45 template <class T, class Method>
  46 class StringMethodComparator
  47     : public std::binary_function<const base::string16&,
  48                                   const base::string16&,
  49                                   bool> {
  50  public:
  51   explicit StringMethodComparator(Method method) : method_(method) { }
  52
  53   // Returns true if lhs preceeds rhs.
  54   bool operator() (T* lhs_t, T* rhs_t) {
  55     return (lhs_t->*method_)() < (rhs_t->*method_)();
  56   }
  57
  58  private:
  59   Method method_;
  60 };
  61
  62 // Sorts the objects in |elements| using the method |method|, which must return
  63 // a string. Sorting is done using a collator, unless a collator can not be
  64 // found in which case the strings are sorted using the operator <.
  65 template <class T, class Method>
  66 void SortStringsUsingMethod(const std::string& locale,
  67                             std::vector<T*>* elements,
  68                             Method method) {
  69   UErrorCode error = U_ZERO_ERROR;
  70   icu::Locale loc(locale.c_str());
  71   scoped_ptr<icu::Collator> collator(icu::Collator::createInstance(loc, error));
  72   if (U_FAILURE(error)) {
  73     sort(elements->begin(), elements->end(),
  74          StringMethodComparator<T, Method>(method));
  75     return;
  76   }
  77
  78   std::sort(elements->begin(), elements->end(),
  79       StringMethodComparatorWithCollator<T, Method>(collator.get(), method));
  80 }
  81
  82 // Compares two elements' string keys and returns true if the first element's
  83 // string key is less than the second element's string key. The Element must
  84 // have a method like the follow format to return the string key.
  85 // const base::string16& GetStringKey() const;
  86 // This uses the locale specified in the constructor.
  87 template <class Element>
  88 class StringComparator : public std::binary_function<const Element&,
  89                                                      const Element&,
  90                                                      bool> {
  91  public:
  92   explicit StringComparator(icu::Collator* collator)
  93       : collator_(collator) { }
  94
  95   // Returns true if lhs precedes rhs.
  96   bool operator()(const Element& lhs, const Element& rhs) {
  97     const base::string16& lhs_string_key = lhs.GetStringKey();
  98     const base::string16& rhs_string_key = rhs.GetStringKey();
  99
 100     return StringComparator<base::string16>(collator_)(lhs_string_key,
 101                                                  rhs_string_key);
 102   }
 103
 104  private:
 105   icu::Collator* collator_;
 106 };
 107
 108 // Specialization of operator() method for base::string16 version.
 109 template <>
 110 UI_BASE_EXPORT inline bool StringComparator<base::string16>::operator()(
 111     const base::string16& lhs,
 112     const base::string16& rhs) {
 113   // If we can not get collator instance for specified locale, just do simple
 114   // string compare.
 115   if (!collator_)
 116     return lhs < rhs;
 117   return base::i18n::CompareString16WithCollator(collator_, lhs, rhs) ==
 118       UCOL_LESS;
 119 }
 120
 121 // In place sorting of |elements| of a vector according to the string key of
 122 // each element in the vector by using collation rules for |locale|.
 123 // |begin_index| points to the start position of elements in the vector which
 124 // want to be sorted. |end_index| points to the end position of elements in the
 125 // vector which want to be sorted
 126 template <class Element>
 127 void SortVectorWithStringKey(const std::string& locale,
 128                              std::vector<Element>* elements,
 129                              unsigned int begin_index,
 130                              unsigned int end_index,
 131                              bool needs_stable_sort) {
 132   DCHECK(begin_index < end_index &&
 133          end_index <= static_cast<unsigned int>(elements->size()));
 134   UErrorCode error = U_ZERO_ERROR;
 135   icu::Locale loc(locale.c_str());
 136   scoped_ptr<icu::Collator> collator(icu::Collator::createInstance(loc, error));
 137   if (U_FAILURE(error))
 138     collator.reset();
 139   StringComparator<Element> c(collator.get());
 140   if (needs_stable_sort) {
 141     stable_sort(elements->begin() + begin_index,
 142                 elements->begin() + end_index,
 143                 c);
 144   } else {
 145     sort(elements->begin() + begin_index, elements->begin() + end_index, c);
 146   }
 147 }
 148
 149 template <class Element>
 150 void SortVectorWithStringKey(const std::string& locale,
 151                              std::vector<Element>* elements,
 152                              bool needs_stable_sort) {
 153   SortVectorWithStringKey<Element>(locale, elements, 0, elements->size(),
 154                                    needs_stable_sort);
 155 }
 156
 157 }  // namespace l10n_util
 158
 159 #endif  // UI_BASE_L10N_L10N_UTIL_COLLATOR_H_