base/i18n/break_iterator.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/break_iterator.h"
   6
   7 #include "base/logging.h"
   8 #include "third_party/icu/source/common/unicode/ubrk.h"
   9 #include "third_party/icu/source/common/unicode/uchar.h"
  10 #include "third_party/icu/source/common/unicode/ustring.h"
  11
  12 namespace base {
  13 namespace i18n {
  14
  15 const size_t npos = static_cast<size_t>(-1);
  16
  17 BreakIterator::BreakIterator(const StringPiece16& str, BreakType break_type)
  18     : iter_(NULL),
  19       string_(str),
  20       break_type_(break_type),
  21       prev_(npos),
  22       pos_(0) {
  23 }
  24
  25 BreakIterator::BreakIterator(const StringPiece16& str, const string16& rules)
  26     : iter_(NULL),
  27       string_(str),
  28       rules_(rules),
  29       break_type_(RULE_BASED),
  30       prev_(npos),
  31       pos_(0) {
  32 }
  33
  34 BreakIterator::~BreakIterator() {
  35   if (iter_)
  36     ubrk_close(static_cast<UBreakIterator*>(iter_));
  37 }
  38
  39 bool BreakIterator::Init() {
  40   UErrorCode status = U_ZERO_ERROR;
  41   UParseError parse_error;
  42   UBreakIteratorType break_type;
  43   switch (break_type_) {
  44     case BREAK_CHARACTER:
  45       break_type = UBRK_CHARACTER;
  46       break;
  47     case BREAK_WORD:
  48       break_type = UBRK_WORD;
  49       break;
  50     case BREAK_LINE:
  51     case BREAK_NEWLINE:
  52     case RULE_BASED: // (Keep compiler happy, break_type not used in this case)
  53       break_type = UBRK_LINE;
  54       break;
  55     default:
  56       NOTREACHED() << "invalid break_type_";
  57       return false;
  58   }
  59   if (break_type_ == RULE_BASED) {
  60     iter_ = ubrk_openRules(rules_.c_str(),
  61                            static_cast<int32_t>(rules_.length()),
  62                            string_.data(),
  63                            static_cast<int32_t>(string_.size()),
  64                            &parse_error,
  65                            &status);
  66     if (U_FAILURE(status)) {
  67       NOTREACHED() << "ubrk_openRules failed to parse rule string at line "
  68           << parse_error.line << ", offset " << parse_error.offset;
  69     }
  70   } else {
  71     iter_ = ubrk_open(break_type,
  72                       NULL,
  73                       string_.data(),
  74                       static_cast<int32_t>(string_.size()),
  75                       &status);
  76     if (U_FAILURE(status)) {
  77       NOTREACHED() << "ubrk_open failed for type " << break_type
  78           << " with error " << status;
  79     }
  80   }
  81
  82   if (U_FAILURE(status)) {
  83     return false;
  84   }
  85
  86   // Move the iterator to the beginning of the string.
  87   ubrk_first(static_cast<UBreakIterator*>(iter_));
  88   return true;
  89 }
  90
  91 bool BreakIterator::Advance() {
  92   int32_t pos;
  93   int32_t status;
  94   prev_ = pos_;
  95   switch (break_type_) {
  96     case BREAK_CHARACTER:
  97     case BREAK_WORD:
  98     case BREAK_LINE:
  99     case RULE_BASED:
 100       pos = ubrk_next(static_cast<UBreakIterator*>(iter_));
 101       if (pos == UBRK_DONE) {
 102         pos_ = npos;
 103         return false;
 104       }
 105       pos_ = static_cast<size_t>(pos);
 106       return true;
 107     case BREAK_NEWLINE:
 108       do {
 109         pos = ubrk_next(static_cast<UBreakIterator*>(iter_));
 110         if (pos == UBRK_DONE)
 111           break;
 112         pos_ = static_cast<size_t>(pos);
 113         status = ubrk_getRuleStatus(static_cast<UBreakIterator*>(iter_));
 114       } while (status >= UBRK_LINE_SOFT && status < UBRK_LINE_SOFT_LIMIT);
 115       if (pos == UBRK_DONE && prev_ == pos_) {
 116         pos_ = npos;
 117         return false;
 118       }
 119       return true;
 120     default:
 121       NOTREACHED() << "invalid break_type_";
 122       return false;
 123   }
 124 }
 125
 126 bool BreakIterator::SetText(const base::char16* text, const size_t length) {
 127   UErrorCode status = U_ZERO_ERROR;
 128   ubrk_setText(static_cast<UBreakIterator*>(iter_),
 129                text, length, &status);
 130   pos_ = 0;  // implicit when ubrk_setText is done
 131   prev_ = npos;
 132   if (U_FAILURE(status)) {
 133     NOTREACHED() << "ubrk_setText failed";
 134     return false;
 135   }
 136   string_ = StringPiece16(text, length);
 137   return true;
 138 }
 139
 140 bool BreakIterator::IsWord() const {
 141   return GetWordBreakStatus() == IS_WORD_BREAK;
 142 }
 143
 144 BreakIterator::WordBreakStatus BreakIterator::GetWordBreakStatus() const {
 145   int32_t status = ubrk_getRuleStatus(static_cast<UBreakIterator*>(iter_));
 146   if (break_type_ != BREAK_WORD && break_type_ != RULE_BASED)
 147     return IS_LINE_OR_CHAR_BREAK;
 148   return status == UBRK_WORD_NONE ? IS_SKIPPABLE_WORD : IS_WORD_BREAK;
 149 }
 150
 151 bool BreakIterator::IsEndOfWord(size_t position) const {
 152   if (break_type_ != BREAK_WORD && break_type_ != RULE_BASED)
 153     return false;
 154
 155   UBreakIterator* iter = static_cast<UBreakIterator*>(iter_);
 156   UBool boundary = ubrk_isBoundary(iter, static_cast<int32_t>(position));
 157   int32_t status = ubrk_getRuleStatus(iter);
 158   return (!!boundary && status != UBRK_WORD_NONE);
 159 }
 160
 161 bool BreakIterator::IsStartOfWord(size_t position) const {
 162   if (break_type_ != BREAK_WORD && break_type_ != RULE_BASED)
 163     return false;
 164
 165   UBreakIterator* iter = static_cast<UBreakIterator*>(iter_);
 166   UBool boundary = ubrk_isBoundary(iter, static_cast<int32_t>(position));
 167   ubrk_next(iter);
 168   int32_t next_status = ubrk_getRuleStatus(iter);
 169   return (!!boundary && next_status != UBRK_WORD_NONE);
 170 }
 171
 172 bool BreakIterator::IsGraphemeBoundary(size_t position) const {
 173   if (break_type_ != BREAK_CHARACTER)
 174     return false;
 175
 176   UBreakIterator* iter = static_cast<UBreakIterator*>(iter_);
 177   return !!ubrk_isBoundary(iter, static_cast<int32_t>(position));
 178 }
 179
 180 string16 BreakIterator::GetString() const {
 181   return GetStringPiece().as_string();
 182 }
 183
 184 StringPiece16 BreakIterator::GetStringPiece() const {
 185   DCHECK(prev_ != npos && pos_ != npos);
 186   return string_.substr(prev_, pos_ - prev_);
 187 }
 188
 189 }  // namespace i18n
 190 }  // namespace base