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      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_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 string16&,
     25                                   const 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 : public std::binary_function<const string16&,
     47                                                            const string16&,
     48                                                            bool> {
     49  public:
     50   explicit StringMethodComparator(Method method) : method_(method) { }
     51 
     52   // Returns true if lhs preceeds rhs.
     53   bool operator() (T* lhs_t, T* rhs_t) {
     54     return (lhs_t->*method_)() < (rhs_t->*method_)();
     55   }
     56 
     57  private:
     58   Method method_;
     59 };
     60 
     61 // Sorts the objects in |elements| using the method |method|, which must return
     62 // a string. Sorting is done using a collator, unless a collator can not be
     63 // found in which case the strings are sorted using the operator <.
     64 template <class T, class Method>
     65 void SortStringsUsingMethod(const std::string& locale,
     66                             std::vector<T*>* elements,
     67                             Method method) {
     68   UErrorCode error = U_ZERO_ERROR;
     69   icu::Locale loc(locale.c_str());
     70   scoped_ptr<icu::Collator> collator(icu::Collator::createInstance(loc, error));
     71   if (U_FAILURE(error)) {
     72     sort(elements->begin(), elements->end(),
     73          StringMethodComparator<T, Method>(method));
     74     return;
     75   }
     76 
     77   std::sort(elements->begin(), elements->end(),
     78       StringMethodComparatorWithCollator<T, Method>(collator.get(), method));
     79 }
     80 
     81 // Compares two elements' string keys and returns true if the first element's
     82 // string key is less than the second element's string key. The Element must
     83 // have a method like the follow format to return the string key.
     84 // const string16& GetStringKey() const;
     85 // This uses the locale specified in the constructor.
     86 template <class Element>
     87 class StringComparator : public std::binary_function<const Element&,
     88                                                      const Element&,
     89                                                      bool> {
     90  public:
     91   explicit StringComparator(icu::Collator* collator)
     92       : collator_(collator) { }
     93 
     94   // Returns true if lhs precedes rhs.
     95   bool operator()(const Element& lhs, const Element& rhs) {
     96     const string16& lhs_string_key = lhs.GetStringKey();
     97     const string16& rhs_string_key = rhs.GetStringKey();
     98 
     99     return StringComparator<string16>(collator_)(lhs_string_key,
    100                                                  rhs_string_key);
    101   }
    102 
    103  private:
    104   icu::Collator* collator_;
    105 };
    106 
    107 // Specialization of operator() method for string16 version.
    108 template <> UI_EXPORT
    109 bool StringComparator<string16>::operator()(const string16& lhs,
    110                                             const string16& rhs);
    111 
    112 // In place sorting of |elements| of a vector according to the string key of
    113 // each element in the vector by using collation rules for |locale|.
    114 // |begin_index| points to the start position of elements in the vector which
    115 // want to be sorted. |end_index| points to the end position of elements in the
    116 // vector which want to be sorted
    117 template <class Element>
    118 void SortVectorWithStringKey(const std::string& locale,
    119                              std::vector<Element>* elements,
    120                              unsigned int begin_index,
    121                              unsigned int end_index,
    122                              bool needs_stable_sort) {
    123   DCHECK(begin_index < end_index &&
    124          end_index <= static_cast<unsigned int>(elements->size()));
    125   UErrorCode error = U_ZERO_ERROR;
    126   icu::Locale loc(locale.c_str());
    127   scoped_ptr<icu::Collator> collator(icu::Collator::createInstance(loc, error));
    128   if (U_FAILURE(error))
    129     collator.reset();
    130   StringComparator<Element> c(collator.get());
    131   if (needs_stable_sort) {
    132     stable_sort(elements->begin() + begin_index,
    133                 elements->begin() + end_index,
    134                 c);
    135   } else {
    136     sort(elements->begin() + begin_index, elements->begin() + end_index, c);
    137   }
    138 }
    139 
    140 template <class Element>
    141 void SortVectorWithStringKey(const std::string& locale,
    142                              std::vector<Element>* elements,
    143                              bool needs_stable_sort) {
    144   SortVectorWithStringKey<Element>(locale, elements, 0, elements->size(),
    145                                    needs_stable_sort);
    146 }
    147 
    148 }  // namespace l10n_util
    149 
    150 #endif  // UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
    151