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base / i18n / case_conversion.cc [blame]
// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "base/i18n/case_conversion.h"
#include <stdint.h>
#include <string>
#include <string_view>
#include "base/numerics/safe_conversions.h"
#include "base/strings/string_util.h"
#include "third_party/icu/source/common/unicode/uchar.h"
#include "third_party/icu/source/common/unicode/unistr.h"
#include "third_party/icu/source/common/unicode/ustring.h"
namespace base {
namespace i18n {
namespace {
// Provides a uniform interface for upper/lower/folding which take take
// slightly varying parameters.
typedef int32_t (*CaseMapperFunction)(UChar* dest, int32_t dest_capacity,
const UChar* src, int32_t src_length,
UErrorCode* error);
int32_t ToUpperMapper(UChar* dest, int32_t dest_capacity,
const UChar* src, int32_t src_length,
UErrorCode* error) {
// Use default locale.
return u_strToUpper(dest, dest_capacity, src, src_length, nullptr, error);
}
int32_t ToLowerMapper(UChar* dest, int32_t dest_capacity,
const UChar* src, int32_t src_length,
UErrorCode* error) {
// Use default locale.
return u_strToLower(dest, dest_capacity, src, src_length, nullptr, error);
}
int32_t FoldCaseMapper(UChar* dest, int32_t dest_capacity,
const UChar* src, int32_t src_length,
UErrorCode* error) {
return u_strFoldCase(dest, dest_capacity, src, src_length,
U_FOLD_CASE_DEFAULT, error);
}
// Provides similar functionality as UnicodeString::caseMap but on
// std::u16string.
std::u16string CaseMap(std::u16string_view string,
CaseMapperFunction case_mapper) {
std::u16string dest;
if (string.empty())
return dest;
// Provide an initial guess that the string length won't change. The typical
// strings we use will very rarely change length in this process, so don't
// optimize for that case.
dest.resize(string.size());
UErrorCode error;
do {
error = U_ZERO_ERROR;
// ICU won't terminate the string if there's not enough room for the null
// terminator, but will otherwise. So we don't need to save room for that.
// Don't use WriteInto, which assumes null terminators.
int32_t new_length = case_mapper(
&dest[0], saturated_cast<int32_t>(dest.size()), string.data(),
saturated_cast<int32_t>(string.size()), &error);
dest.resize(new_length);
} while (error == U_BUFFER_OVERFLOW_ERROR);
return dest;
}
} // namespace
std::u16string ToLower(std::u16string_view string) {
return CaseMap(string, &ToLowerMapper);
}
std::u16string ToUpper(std::u16string_view string) {
return CaseMap(string, &ToUpperMapper);
}
std::u16string FoldCase(std::u16string_view string) {
return CaseMap(string, &FoldCaseMapper);
}
} // namespace i18n
} // namespace base