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      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 #ifndef BASE_I18N_WORD_ITERATOR_H_
      6 #define BASE_I18N_WORD_ITERATOR_H_
      7 
      8 #include <string>
      9 #include <vector>
     10 
     11 #include "unicode/uchar.h"
     12 
     13 #include "base/basictypes.h"
     14 
     15 // The WordIterator class iterates through the words and word breaks
     16 // in a string.  (In the string " foo bar! ", the word breaks are at the
     17 // periods in ". .foo. .bar.!. .".)
     18 //
     19 // To extract the words from a string, move a WordIterator through the
     20 // string and test whether IsWord() is true.  E.g.,
     21 //   WordIterator iter(str, WordIterator::BREAK_WORD);
     22 //   if (!iter.Init()) return false;
     23 //   while (iter.Advance()) {
     24 //     if (iter.IsWord()) {
     25 //       // region [iter.prev(),iter.pos()) contains a word.
     26 //       LOG(INFO) << "word: " << iter.GetWord();
     27 //     }
     28 //   }
     29 
     30 
     31 class WordIterator {
     32  public:
     33   enum BreakType {
     34     BREAK_WORD,
     35     BREAK_LINE
     36   };
     37 
     38   // Requires |str| to live as long as the WordIterator does.
     39   WordIterator(const std::wstring& str, BreakType break_type);
     40   ~WordIterator();
     41 
     42   // Init() must be called before any of the iterators are valid.
     43   // Returns false if ICU failed to initialize.
     44   bool Init();
     45 
     46   // Return the current break position within the string,
     47   // or WordIterator::npos when done.
     48   size_t pos() const { return pos_; }
     49   // Return the value of pos() returned before Advance() was last called.
     50   size_t prev() const { return prev_; }
     51 
     52   // Advance to the next break.  Returns false if we've run past the end of
     53   // the string.  (Note that the very last "word break" is after the final
     54   // character in the string, and when we advance to that position it's the
     55   // last time Advance() returns true.)
     56   bool Advance();
     57 
     58   // Returns true if the break we just hit is the end of a word.
     59   // (Otherwise, the break iterator just skipped over e.g. whitespace
     60   // or punctuation.)
     61   bool IsWord() const;
     62 
     63   // Return the word between prev() and pos().
     64   // Advance() must have been called successfully at least once
     65   // for pos() to have advanced to somewhere useful.
     66   std::wstring GetWord() const;
     67 
     68  private:
     69   // ICU iterator.
     70   void* iter_;
     71 #if !defined(WCHAR_T_IS_UTF16)
     72   std::vector<UChar> chars_;
     73 #endif
     74 
     75   // The string we're iterating over.
     76   const std::wstring& string_;
     77 
     78   // The breaking style (word/line).
     79   BreakType break_type_;
     80 
     81   // Previous and current iterator positions.
     82   size_t prev_, pos_;
     83 
     84   DISALLOW_COPY_AND_ASSIGN(WordIterator);
     85 };
     86 
     87 #endif  // BASE_I18N_WORD_ITERATOR_H__
     88