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// Copyright 2008, Google Inc.
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef BASE_WORD_ITERATOR_H__
#define BASE_WORD_ITERATOR_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.
int pos() const { return pos_; }
// Return the value of pos() returned before Advance() was last called.
int prev() const { return prev_; }
// A special position value indicating "end of string".
static const int npos;
// 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 {
DCHECK(prev_ >= 0 && pos_ >= 0);
return string_.substr(prev_, pos_ - prev_);
}
private:
// ICU iterator.
void* iter_;
// The string we're iterating over.
const std::wstring& string_;
// The breaking style (word/line).
BreakType break_type_;
// Previous and current iterator positions.
int prev_, pos_;
DISALLOW_EVIL_CONSTRUCTORS(WordIterator);
};
#endif // BASE_WORD_ITERATOR_H__
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