base/i18n/word_iterator.cc

   1 // Copyright (c) 2009 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/word_iterator.h"
   6
   7 #include "base/logging.h"
   8 #include "unicode/ubrk.h"
   9 #include "unicode/ustring.h"
  10
  11 const size_t npos = -1;
  12
  13 WordIterator::WordIterator(const std::wstring& str, BreakType break_type)
  14     : iter_(NULL),
  15       string_(str),
  16       break_type_(break_type),
  17       prev_(npos),
  18       pos_(0) {
  19 }
  20
  21 WordIterator::~WordIterator() {
  22   if (iter_)
  23     ubrk_close(iter_);
  24 }
  25
  26 bool WordIterator::Init() {
  27   UErrorCode status = U_ZERO_ERROR;
  28   UBreakIteratorType break_type;
  29   switch (break_type_) {
  30     case BREAK_WORD:
  31       break_type = UBRK_WORD;
  32       break;
  33     case BREAK_LINE:
  34       break_type = UBRK_LINE;
  35       break;
  36     default:
  37       NOTREACHED();
  38       break_type = UBRK_LINE;
  39   }
  40 #if defined(WCHAR_T_IS_UTF16)
  41   iter_ = ubrk_open(break_type, NULL,
  42                     string_.data(), static_cast<int32_t>(string_.size()),
  43                     &status);
  44 #else  // WCHAR_T_IS_UTF16
  45   // When wchar_t is wider than UChar (16 bits), transform |string_| into a
  46   // UChar* string.  Size the UChar* buffer to be large enough to hold twice
  47   // as many UTF-16 code points as there are UCS-4 characters, in case each
  48   // character translates to a UTF-16 surrogate pair, and leave room for a NUL
  49   // terminator.
  50   // TODO(avi): avoid this alloc
  51   chars_.resize(string_.length() * sizeof(UChar) + 1);
  52
  53   UErrorCode error = U_ZERO_ERROR;
  54   int32_t destLength;
  55   u_strFromWCS(&chars_[0], chars_.size(), &destLength, string_.data(),
  56                string_.length(), &error);
  57
  58   iter_ = ubrk_open(break_type, NULL, &chars_[0], destLength, &status);
  59 #endif
  60   if (U_FAILURE(status)) {
  61     NOTREACHED() << "ubrk_open failed";
  62     return false;
  63   }
  64   ubrk_first(iter_);  // Move the iterator to the beginning of the string.
  65   return true;
  66 }
  67
  68 bool WordIterator::Advance() {
  69   prev_ = pos_;
  70   const int32_t pos = ubrk_next(iter_);
  71   if (pos == UBRK_DONE) {
  72     pos_ = npos;
  73     return false;
  74   } else {
  75     pos_ = static_cast<size_t>(pos);
  76     return true;
  77   }
  78 }
  79
  80 bool WordIterator::IsWord() const {
  81   return (ubrk_getRuleStatus(iter_) != UBRK_WORD_NONE);
  82 }
  83
  84 std::wstring WordIterator::GetWord() const {
  85   DCHECK(prev_ != npos && pos_ != npos);
  86 #if defined(WCHAR_T_IS_UTF16)
  87   return string_.substr(prev_, pos_ - prev_);
  88 #else  // WCHAR_T_IS_UTF16
  89   // See comment in Init().  If there are no surrogate pairs,
  90   // |out_length| will be exactly |in_length|, if there are surrogate
  91   // pairs it will be less than |in_length|.
  92   int32_t out_length;
  93   UErrorCode error = U_ZERO_ERROR;
  94   const int32_t in_length = pos_ - prev_;
  95   std::vector<std::wstring::value_type> out_buffer(in_length);
  96   u_strToWCS(&out_buffer[0], in_length, &out_length,
  97              &chars_[prev_], in_length, &error);
  98   DCHECK_LE(out_length, in_length);
  99   return std::wstring(&out_buffer[0], out_length);
 100 #endif
 101 }