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Side by Side Diff: base/i18n/break_iterator.h

Issue 6979019: base/i18n: Make BreakIterator::IsWord() more readable. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Created 9 years, 7 months ago
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1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 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 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #ifndef BASE_I18N_BREAK_ITERATOR_H_ 5 #ifndef BASE_I18N_BREAK_ITERATOR_H_
6 #define BASE_I18N_BREAK_ITERATOR_H_ 6 #define BASE_I18N_BREAK_ITERATOR_H_
7 #pragma once 7 #pragma once
8 8
9 #include "base/basictypes.h" 9 #include "base/basictypes.h"
10 #include "base/string16.h" 10 #include "base/string16.h"
(...skipping 23 matching lines...) Expand all
34 // (Thai does not use spaces between words). Therefore, this is NOT the same 34 // (Thai does not use spaces between words). Therefore, this is NOT the same
35 // as breaking only at space-equivalent characters where its former 35 // as breaking only at space-equivalent characters where its former
36 // name (BREAK_SPACE) implied. 36 // name (BREAK_SPACE) implied.
37 // 37 //
38 // Under BREAK_NEWLINE mode, all characters are included in the returned 38 // Under BREAK_NEWLINE mode, all characters are included in the returned
39 // string, breking only when a newline-equivalent character is encountered 39 // string, breking only when a newline-equivalent character is encountered
40 // (eg. in the UTF-16 equivalent of the string "foo\nbar!\n\n", the line 40 // (eg. in the UTF-16 equivalent of the string "foo\nbar!\n\n", the line
41 // breaks are at the periods in ".foo\n.bar\n.\n."). 41 // breaks are at the periods in ".foo\n.bar\n.\n.").
42 // 42 //
43 // To extract the words from a string, move a BREAK_WORD BreakIterator 43 // To extract the words from a string, move a BREAK_WORD BreakIterator
44 // through the string and test whether IsWord() is true. E.g., 44 // through the string and test whether IsWord() is true. E.g.,
45 // BreakIterator iter(&str, BreakIterator::BREAK_WORD); 45 // BreakIterator iter(str, BreakIterator::BREAK_WORD);
46 // if (!iter.Init()) return false; 46 // if (!iter.Init())
47 // return false;
47 // while (iter.Advance()) { 48 // while (iter.Advance()) {
48 // if (iter.IsWord()) { 49 // if (iter.IsWord()) {
49 // // region [iter.prev(),iter.pos()) contains a word. 50 // // Region [iter.prev(), iter.pos()) contains a word.
50 // VLOG(1) << "word: " << iter.GetString(); 51 // VLOG(1) << "word: " << iter.GetString();
51 // } 52 // }
52 // } 53 // }
53 54
54 namespace base { 55 namespace base {
55 namespace i18n { 56 namespace i18n {
56 57
57 class BreakIterator { 58 class BreakIterator {
58 public: 59 public:
59 enum BreakType { 60 enum BreakType {
60 BREAK_WORD, 61 BREAK_WORD,
61 BREAK_LINE, 62 BREAK_LINE,
62 // TODO(jshin): Remove this after reviewing call sites. 63 // TODO(jshin): Remove this after reviewing call sites.
63 // If call sites really need break only on space-like characters 64 // If call sites really need break only on space-like characters
64 // implement it separately. 65 // implement it separately.
65 BREAK_SPACE = BREAK_LINE, 66 BREAK_SPACE = BREAK_LINE,
66 BREAK_NEWLINE, 67 BREAK_NEWLINE,
67 }; 68 };
68 69
69 // Requires |str| to live as long as the BreakIterator does. 70 // Requires |str| to live as long as the BreakIterator does.
70 BreakIterator(const string16& str, BreakType break_type); 71 BreakIterator(const string16& str, BreakType break_type);
71 ~BreakIterator(); 72 ~BreakIterator();
72 73
73 // Init() must be called before any of the iterators are valid. 74 // Init() must be called before any of the iterators are valid.
74 // Returns false if ICU failed to initialize. 75 // Returns false if ICU failed to initialize.
75 bool Init(); 76 bool Init();
76 77
77 // Return the current break position within the string,
78 // or BreakIterator::npos when done.
79 size_t pos() const { return pos_; }
80
81 // Return the value of pos() returned before Advance() was last called.
82 size_t prev() const { return prev_; }
83
84 // Advance to the next break. Returns false if we've run past the end of 78 // Advance to the next break. Returns false if we've run past the end of
85 // the string. (Note that the very last "break" is after the final 79 // the string. (Note that the very last "break" is after the final
86 // character in the string, and when we advance to that position it's the 80 // character in the string, and when we advance to that position it's the
87 // last time Advance() returns true.) 81 // last time Advance() returns true.)
88 bool Advance(); 82 bool Advance();
89 83
90 // Under BREAK_WORD mode, returns true if the break we just hit is the 84 // Under BREAK_WORD mode, returns true if the break we just hit is the
91 // end of a word. (Otherwise, the break iterator just skipped over e.g. 85 // end of a word. (Otherwise, the break iterator just skipped over e.g.
92 // whitespace or punctuation.) Under BREAK_LINE and BREAK_NEWLINE modes, 86 // whitespace or punctuation.) Under BREAK_LINE and BREAK_NEWLINE modes,
93 // this distinction doesn't apply and it always retuns false. 87 // this distinction doesn't apply and it always retuns false.
94 bool IsWord() const; 88 bool IsWord() const;
95 89
96 // Return the string between prev() and pos(). 90 // Returns the string between prev() and pos().
97 // Advance() must have been called successfully at least once 91 // Advance() must have been called successfully at least once for pos() to
98 // for pos() to have advanced to somewhere useful. 92 // have advanced to somewhere useful.
99 string16 GetString() const; 93 string16 GetString() const;
100 94
95 // Returns the value of pos() returned before Advance() was last called.
96 size_t prev() const { return prev_; }
97
98 // Returns the current break position within the string,
99 // or BreakIterator::npos when done.
100 size_t pos() const { return pos_; }
101
101 private: 102 private:
102 // ICU iterator, avoiding ICU ubrk.h dependence. 103 // ICU iterator, avoiding ICU ubrk.h dependence.
103 // This is actually an ICU UBreakiterator* type, which turns out to be 104 // This is actually an ICU UBreakiterator* type, which turns out to be
104 // a typedef for a void* in the ICU headers. Using void* directly prevents 105 // a typedef for a void* in the ICU headers. Using void* directly prevents
105 // callers from needing access to the ICU public headers directory. 106 // callers from needing access to the ICU public headers directory.
106 void* iter_; 107 void* iter_;
107 108
108 // The string we're iterating over. 109 // The string we're iterating over.
109 const string16& string_; 110 const string16& string_;
110 111
111 // The breaking style (word/space/newline). 112 // The breaking style (word/space/newline).
112 BreakType break_type_; 113 BreakType break_type_;
113 114
114 // Previous and current iterator positions. 115 // Previous and current iterator positions.
115 size_t prev_, pos_; 116 size_t prev_, pos_;
116 117
117 DISALLOW_COPY_AND_ASSIGN(BreakIterator); 118 DISALLOW_COPY_AND_ASSIGN(BreakIterator);
118 }; 119 };
119 120
120 } // namespace i18n 121 } // namespace i18n
121 } // namespace base 122 } // namespace base
122 123
123 #endif // BASE_I18N_BREAK_ITERATOR_H_ 124 #endif // BASE_I18N_BREAK_ITERATOR_H_
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