chrome/browser/spellchecker/word_trimmer.cc

   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
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/spellchecker/word_trimmer.h"
   6
   7 #include <algorithm>
   8 #include <vector>
   9
  10 #include "base/i18n/break_iterator.h"
  11
  12 base::string16 TrimWords(size_t* start,
  13                          size_t end,
  14                          const base::string16& text,
  15                          size_t keep) {
  16   if (*start > text.length() || *start > end)
  17     return text;
  18   base::i18n::BreakIterator iter(text, base::i18n::BreakIterator::BREAK_WORD);
  19   if (!iter.Init())
  20     return text;
  21   // A circular buffer of the last |keep + 1| words seen before position |start|
  22   // in |text|.
  23   std::vector<size_t> word_offset(keep + 1, 0);
  24   size_t first = std::string::npos;
  25   size_t last = std::string::npos;
  26   while (iter.Advance()) {
  27     if (iter.IsWord()) {
  28       word_offset[keep] = iter.prev();
  29       if ((*start >= iter.prev() && *start < iter.pos()) ||
  30           (end > iter.prev() && end <= iter.pos())) {
  31         if (first == std::string::npos)
  32           first = word_offset[0];
  33         last = iter.pos();
  34       }
  35       if (first == std::string::npos) {
  36         std::rotate(word_offset.begin(),
  37                     word_offset.begin() + 1,
  38                     word_offset.end());
  39       }
  40       if (iter.prev() > end && keep) {
  41         last = iter.pos();
  42         keep--;
  43       }
  44     }
  45   }
  46   if (first == std::string::npos)
  47     return text;
  48   *start -= first;
  49   return text.substr(first, last - first);
  50 }