base/i18n/case_conversion.cc

   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 #include "base/i18n/case_conversion.h"
   6
   7 #include "base/numerics/safe_conversions.h"
   8 #include "base/strings/string16.h"
   9 #include "base/strings/string_util.h"
  10 #include "third_party/icu/source/common/unicode/uchar.h"
  11 #include "third_party/icu/source/common/unicode/unistr.h"
  12 #include "third_party/icu/source/common/unicode/ustring.h"
  13
  14 namespace base {
  15 namespace i18n {
  16
  17 namespace {
  18
  19 // Provides a uniform interface for upper/lower/folding which take take
  20 // slightly varying parameters.
  21 typedef int32_t (*CaseMapperFunction)(UChar* dest, int32_t dest_capacity,
  22                                       const UChar* src, int32_t src_length,
  23                                       UErrorCode* error);
  24
  25 int32_t ToUpperMapper(UChar* dest, int32_t dest_capacity,
  26                       const UChar* src, int32_t src_length,
  27                       UErrorCode* error) {
  28   // Use default locale.
  29   return u_strToUpper(dest, dest_capacity, src, src_length, NULL, error);
  30 }
  31
  32 int32_t ToLowerMapper(UChar* dest, int32_t dest_capacity,
  33                       const UChar* src, int32_t src_length,
  34                       UErrorCode* error) {
  35   // Use default locale.
  36   return u_strToLower(dest, dest_capacity, src, src_length, NULL, error);
  37 }
  38
  39 int32_t FoldCaseMapper(UChar* dest, int32_t dest_capacity,
  40                        const UChar* src, int32_t src_length,
  41                        UErrorCode* error) {
  42   return u_strFoldCase(dest, dest_capacity, src, src_length,
  43                        U_FOLD_CASE_DEFAULT, error);
  44 }
  45
  46 // Provides similar functionality as UnicodeString::caseMap but on string16.
  47 string16 CaseMap(StringPiece16 string, CaseMapperFunction case_mapper) {
  48   string16 dest;
  49   if (string.empty())
  50     return dest;
  51
  52   // Provide an initial guess that the string length won't change. The typical
  53   // strings we use will very rarely change length in this process, so don't
  54   // optimize for that case.
  55   dest.resize(string.size());
  56
  57   UErrorCode error;
  58   do {
  59     error = U_ZERO_ERROR;
  60
  61     // ICU won't terminate the string if there's not enough room for the null
  62     // terminator, but will otherwise. So we don't need to save room for that.
  63     // Don't use WriteInto, which assumes null terminators.
  64     int32_t new_length = case_mapper(
  65         &dest[0], saturated_cast<int32_t>(dest.size()),
  66         string.data(), saturated_cast<int32_t>(string.size()),
  67         &error);
  68     dest.resize(new_length);
  69   } while (error == U_BUFFER_OVERFLOW_ERROR);
  70   return dest;
  71 }
  72
  73 }  // namespace
  74
  75 string16 ToLower(StringPiece16 string) {
  76   return CaseMap(string, &ToLowerMapper);
  77 }
  78
  79 string16 ToUpper(StringPiece16 string) {
  80   return CaseMap(string, &ToUpperMapper);
  81 }
  82
  83 string16 FoldCase(StringPiece16 string) {
  84   return CaseMap(string, &FoldCaseMapper);
  85 }
  86
  87 }  // namespace i18n
  88 }  // namespace base