break_iterator.cc revision 5f1c94371a64b3196d4be9466099bb892df9b88e 
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
12namespace base {
13namespace i18n {
14
15const size_t npos = static_cast<size_t>(-1);
16
17BreakIterator::BreakIterator(const string16& str, BreakType break_type)
18    : iter_(NULL),
19      string_(str),
20      break_type_(break_type),
21      prev_(npos),
22      pos_(0) {
23}
24
25BreakIterator::BreakIterator(const string16& 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
34BreakIterator::~BreakIterator() {
35  if (iter_)
36    ubrk_close(static_cast<UBreakIterator*>(iter_));
37}
38
39bool 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";
78    }
79  }
80
81  if (U_FAILURE(status)) {
82    return false;
83  }
84
85  // Move the iterator to the beginning of the string.
86  ubrk_first(static_cast<UBreakIterator*>(iter_));
87  return true;
88}
89
90bool BreakIterator::Advance() {
91  int32_t pos;
92  int32_t status;
93  prev_ = pos_;
94  switch (break_type_) {
95    case BREAK_CHARACTER:
96    case BREAK_WORD:
97    case BREAK_LINE:
98    case RULE_BASED:
99      pos = ubrk_next(static_cast<UBreakIterator*>(iter_));
100      if (pos == UBRK_DONE) {
101        pos_ = npos;
102        return false;
103      }
104      pos_ = static_cast<size_t>(pos);
105      return true;
106    case BREAK_NEWLINE:
107      do {
108        pos = ubrk_next(static_cast<UBreakIterator*>(iter_));
109        if (pos == UBRK_DONE)
110          break;
111        pos_ = static_cast<size_t>(pos);
112        status = ubrk_getRuleStatus(static_cast<UBreakIterator*>(iter_));
113      } while (status >= UBRK_LINE_SOFT && status < UBRK_LINE_SOFT_LIMIT);
114      if (pos == UBRK_DONE && prev_ == pos_) {
115        pos_ = npos;
116        return false;
117      }
118      return true;
119    default:
120      NOTREACHED() << "invalid break_type_";
121      return false;
122  }
123}
124
125bool BreakIterator::SetText(const base::char16* text, const size_t length) {
126  UErrorCode status = U_ZERO_ERROR;
127  ubrk_setText(static_cast<UBreakIterator*>(iter_),
128               text, length, &status);
129  pos_ = 0;  // implicit when ubrk_setText is done
130  prev_ = npos;
131  if (U_FAILURE(status)) {
132    NOTREACHED() << "ubrk_setText failed";
133    return false;
134  }
135  return true;
136}
137
138bool BreakIterator::IsWord() const {
139  int32_t status = ubrk_getRuleStatus(static_cast<UBreakIterator*>(iter_));
140  if (break_type_ != BREAK_WORD && break_type_ != RULE_BASED)
141    return false;
142  return status != UBRK_WORD_NONE;
143}
144
145bool BreakIterator::IsEndOfWord(size_t position) const {
146  if (break_type_ != BREAK_WORD && break_type_ != RULE_BASED)
147    return false;
148
149  UBreakIterator* iter = static_cast<UBreakIterator*>(iter_);
150  UBool boundary = ubrk_isBoundary(iter, static_cast<int32_t>(position));
151  int32_t status = ubrk_getRuleStatus(iter);
152  return (!!boundary && status != UBRK_WORD_NONE);
153}
154
155bool BreakIterator::IsStartOfWord(size_t position) const {
156  if (break_type_ != BREAK_WORD && break_type_ != RULE_BASED)
157    return false;
158
159  UBreakIterator* iter = static_cast<UBreakIterator*>(iter_);
160  UBool boundary = ubrk_isBoundary(iter, static_cast<int32_t>(position));
161  ubrk_next(iter);
162  int32_t next_status = ubrk_getRuleStatus(iter);
163  return (!!boundary && next_status != UBRK_WORD_NONE);
164}
165
166bool BreakIterator::IsGraphemeBoundary(size_t position) const {
167  if (break_type_ != BREAK_CHARACTER)
168    return false;
169
170  UBreakIterator* iter = static_cast<UBreakIterator*>(iter_);
171  return !!ubrk_isBoundary(iter, static_cast<int32_t>(position));
172}
173
174string16 BreakIterator::GetString() const {
175  DCHECK(prev_ != npos && pos_ != npos);
176  return string_.substr(prev_, pos_ - prev_);
177}
178
179}  // namespace i18n
180}  // namespace base
181