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
11const size_t npos = -1;
12
13WordIterator::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
21WordIterator::~WordIterator() {
22  if (iter_)
23    ubrk_close(iter_);
24}
25
26bool 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
68bool 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
80bool WordIterator::IsWord() const {
81  return (ubrk_getRuleStatus(iter_) != UBRK_WORD_NONE);
82}
83
84std::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}
102