third_party/WebKit/Source/platform/text/TextBoundaries.cpp

/*
 * Copyright (C) 2006, 2007 Apple Inc.  All rights reserved.
 * Copyright (C) 2009 Dominik Roettsches <dominik.roettsches@access-company.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``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 APPLE COMPUTER, INC. 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.
 */

#include "platform/text/TextBoundaries.h"

#include "platform/text/TextBreakIterator.h"
#include "platform/wtf/text/CharacterNames.h"
#include "platform/wtf/text/StringImpl.h"

namespace blink {

int EndOfFirstWordBoundaryContext(const UChar* characters, int length) {
  for (int i = 0; i < length;) {
    int first = i;
    UChar32 ch;
    U16_NEXT(characters, i, length, ch);
    if (!RequiresContextForWordBoundary(ch))
      return first;
  }
  return length;
}

int StartOfLastWordBoundaryContext(const UChar* characters, int length) {
  for (int i = length; i > 0;) {
    int last = i;
    UChar32 ch;
    U16_PREV(characters, 0, i, ch);
    if (!RequiresContextForWordBoundary(ch))
      return last;
  }
  return 0;
}

int FindNextWordForward(const UChar* chars, int len, int position) {
  TextBreakIterator* it = WordBreakIterator(chars, len);

    position = it->following(position);
    while (position != kTextBreakDone) {
      // We stop searching when the character preceeding the break
      // is alphanumeric or underscore.
      if (position < len &&
          (WTF::Unicode::IsAlphanumeric(chars[position - 1]) ||
           chars[position - 1] == kLowLineCharacter))
        return position;

      position = it->following(position);
    }

    return len;
}

int FindNextWordBackward(const UChar* chars, int len, int position) {
  TextBreakIterator* it = WordBreakIterator(chars, len);

  position = it->preceding(position);
  while (position != kTextBreakDone) {
    // We stop searching when the character following the break
    // is alphanumeric or underscore.
    if (position > 0 && (WTF::Unicode::IsAlphanumeric(chars[position]) ||
                         chars[position] == kLowLineCharacter))
      return position;

    position = it->preceding(position);
  }

  return 0;
}

int FindWordStartBoundary(const UChar* chars, int len, int position) {
  TextBreakIterator* it = WordBreakIterator(chars, len);
  it->following(position);
  return it->previous();
}

int FindWordEndBoundary(const UChar* chars, int len, int position) {
  TextBreakIterator* it = WordBreakIterator(chars, len);
  int end = it->following(position);
  return end < 0 ? it->last() : end;
}

}  // namespace blink