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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
#define UI_BASE_L10N_L10N_UTIL_COLLATOR_H_
#include <stddef.h>
#include <algorithm>
#include <functional>
#include <memory>
#include <string>
#include <vector>
#include "base/i18n/string_compare.h"
#include "third_party/icu/source/i18n/unicode/coll.h"
#include "ui/base/ui_base_export.h"
namespace l10n_util {
// Used by SortStringsUsingMethod. Invokes a method on the objects passed to
// operator (), comparing the string results using a collator.
template <class T, class Method>
class StringMethodComparatorWithCollator {
public:
StringMethodComparatorWithCollator(icu::Collator* collator, Method method)
: collator_(collator),
method_(method) { }
// Returns true if lhs preceeds rhs.
bool operator() (T* lhs_t, T* rhs_t) {
return base::i18n::CompareString16WithCollator(
*collator_, (lhs_t->*method_)(), (rhs_t->*method_)()) ==
UCOL_LESS;
}
private:
icu::Collator* collator_;
Method method_;
};
// Used by SortStringsUsingMethod. Invokes a method on the objects passed to
// operator (), comparing the string results using <.
template <class T, class Method>
class StringMethodComparator {
public:
explicit StringMethodComparator(Method method) : method_(method) { }
// Returns true if lhs preceeds rhs.
bool operator() (T* lhs_t, T* rhs_t) {
return (lhs_t->*method_)() < (rhs_t->*method_)();
}
private:
Method method_;
};
// Sorts the objects in |elements| using the method |method|, which must return
// a string. Sorting is done using a collator, unless a collator can not be
// found in which case the strings are sorted using the operator <.
template <class T, class Method>
void SortStringsUsingMethod(const std::string& locale,
std::vector<T*>* elements,
Method method) {
UErrorCode error = U_ZERO_ERROR;
icu::Locale loc(locale.c_str());
std::unique_ptr<icu::Collator> collator(
icu::Collator::createInstance(loc, error));
if (U_FAILURE(error)) {
sort(elements->begin(), elements->end(),
StringMethodComparator<T, Method>(method));
return;
}
std::sort(elements->begin(), elements->end(),
StringMethodComparatorWithCollator<T, Method>(collator.get(), method));
}
// Compares two elements' string keys and returns true if the first element's
// string key is less than the second element's string key. The Element must
// have a method like the follow format to return the string key.
// const base::string16& GetStringKey() const;
// This uses the locale specified in the constructor.
template <class Element>
class StringComparator {
public:
explicit StringComparator(icu::Collator* collator)
: collator_(collator) { }
// Returns true if lhs precedes rhs.
bool operator()(const Element& lhs, const Element& rhs) const {
const base::string16& lhs_string_key = lhs.GetStringKey();
const base::string16& rhs_string_key = rhs.GetStringKey();
return StringComparator<base::string16>(collator_)(lhs_string_key,
rhs_string_key);
}
private:
icu::Collator* collator_;
};
// Specialization of operator() method for base::string16 version.
template <>
UI_BASE_EXPORT inline bool StringComparator<base::string16>::operator()(
const base::string16& lhs,
const base::string16& rhs) const {
// If we can not get collator instance for specified locale, just do simple
// string compare.
if (!collator_)
return lhs < rhs;
return base::i18n::CompareString16WithCollator(*collator_, lhs, rhs) ==
UCOL_LESS;
}
// In place sorting of |elements| of a vector according to the string key of
// each element in the vector by using collation rules for |locale|.
// |begin_index| points to the start position of elements in the vector which
// want to be sorted. |end_index| points to the end position of elements in the
// vector which want to be sorted.
template <class Element>
void SortVectorWithStringKey(const std::string& locale,
std::vector<Element>* elements,
size_t begin_index,
size_t end_index,
bool needs_stable_sort) {
DCHECK_LT(begin_index, end_index);
DCHECK_LE(end_index, elements->size());
UErrorCode error = U_ZERO_ERROR;
icu::Locale loc(locale.c_str());
std::unique_ptr<icu::Collator> collator(
icu::Collator::createInstance(loc, error));
if (U_FAILURE(error))
collator.reset();
StringComparator<Element> c(collator.get());
if (needs_stable_sort) {
stable_sort(elements->begin() + begin_index,
elements->begin() + end_index,
c);
} else {
sort(elements->begin() + begin_index, elements->begin() + end_index, c);
}
}
template <class Element>
void SortVectorWithStringKey(const std::string& locale,
std::vector<Element>* elements,
bool needs_stable_sort) {
SortVectorWithStringKey<Element>(locale, elements, 0, elements->size(),
needs_stable_sort);
}
} // namespace l10n_util
#endif // UI_BASE_L10N_L10N_UTIL_COLLATOR_H_