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diff --git a/base/i18n/word_iterator.h b/base/i18n/word_iterator.h
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+++ b/base/i18n/word_iterator.h
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+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_I18N_WORD_ITERATOR_H_
+#define BASE_I18N_WORD_ITERATOR_H_
+
+#include <string>
+#include <vector>
+
+#include "unicode/uchar.h"
+
+#include "base/basictypes.h"
+
+// The WordIterator class iterates through the words and word breaks
+// in a string.  (In the string " foo bar! ", the word breaks are at the
+// periods in ". .foo. .bar.!. .".)
+//
+// To extract the words from a string, move a WordIterator through the
+// string and test whether IsWord() is true.  E.g.,
+//   WordIterator iter(str, WordIterator::BREAK_WORD);
+//   if (!iter.Init()) return false;
+//   while (iter.Advance()) {
+//     if (iter.IsWord()) {
+//       // region [iter.prev(),iter.pos()) contains a word.
+//       LOG(INFO) << "word: " << iter.GetWord();
+//     }
+//   }
+
+
+class WordIterator {
+ public:
+  enum BreakType {
+    BREAK_WORD,
+    BREAK_LINE
+  };
+
+  // Requires |str| to live as long as the WordIterator does.
+  WordIterator(const std::wstring& str, BreakType break_type);
+  ~WordIterator();
+
+  // Init() must be called before any of the iterators are valid.
+  // Returns false if ICU failed to initialize.
+  bool Init();
+
+  // Return the current break position within the string,
+  // or WordIterator::npos when done.
+  size_t pos() const { return pos_; }
+  // Return the value of pos() returned before Advance() was last called.
+  size_t prev() const { return prev_; }
+
+  // Advance to the next break.  Returns false if we've run past the end of
+  // the string.  (Note that the very last "word break" is after the final
+  // character in the string, and when we advance to that position it's the
+  // last time Advance() returns true.)
+  bool Advance();
+
+  // Returns true if the break we just hit is the end of a word.
+  // (Otherwise, the break iterator just skipped over e.g. whitespace
+  // or punctuation.)
+  bool IsWord() const;
+
+  // Return the word between prev() and pos().
+  // Advance() must have been called successfully at least once
+  // for pos() to have advanced to somewhere useful.
+  std::wstring GetWord() const;
+
+ private:
+  // ICU iterator.
+  void* iter_;
+#if !defined(WCHAR_T_IS_UTF16)
+  std::vector<UChar> chars_;
+#endif
+
+  // The string we're iterating over.
+  const std::wstring& string_;
+
+  // The breaking style (word/line).
+  BreakType break_type_;
+
+  // Previous and current iterator positions.
+  size_t prev_, pos_;
+
+  DISALLOW_COPY_AND_ASSIGN(WordIterator);
+};
+
+#endif  // BASE_I18N_WORD_ITERATOR_H__