third_party/WebKit/Source/core/html/forms/TypeAhead.cpp

/*
 * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
 * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
 *           (C) 1999 Antti Koivisto (koivisto@kde.org)
 *           (C) 2001 Dirk Mueller (mueller@kde.org)
 * Copyright (C) 2004, 2005, 2006, 2007, 2009, 2010, 2011 Apple Inc. All rights
 * reserved.
 *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
 * Copyright (C) 2010 Google Inc. All rights reserved.
 * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
 * (http://www.torchmobile.com/)
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 *
 */

#include "core/html/forms/TypeAhead.h"

#include "core/events/KeyboardEvent.h"
#include "wtf/text/CharacterNames.h"

using namespace WTF::Unicode;

namespace blink {

TypeAhead::TypeAhead(TypeAheadDataSource* dataSource)
    : m_dataSource(dataSource), m_lastTypeTime(0), m_repeatingChar(0) {}

static const double typeAheadTimeout = 1;  // in seconds

static String stripLeadingWhiteSpace(const String& string) {
  unsigned length = string.length();

  unsigned i;
  for (i = 0; i < length; ++i) {
    if (string[i] != noBreakSpaceCharacter && !isSpaceOrNewline(string[i]))
      break;
  }

  return string.substring(i, length - i);
}

int TypeAhead::handleEvent(KeyboardEvent* event, MatchModeFlags matchMode) {
  if (event->platformTimeStamp() < m_lastTypeTime)
    return -1;

  int optionCount = m_dataSource->optionCount();
  double delta = event->platformTimeStamp() - m_lastTypeTime;
  m_lastTypeTime = event->platformTimeStamp();

  UChar c = event->charCode();

  if (delta > typeAheadTimeout)
    m_buffer.clear();

  m_buffer.append(c);

  if (optionCount < 1)
    return -1;

  int searchStartOffset = 1;
  String prefix;
  if (matchMode & CycleFirstChar && c == m_repeatingChar) {
    // The user is likely trying to cycle through all the items starting
    // with this character, so just search on the character.
    prefix = String(&c, 1);
    m_repeatingChar = c;
  } else if (matchMode & MatchPrefix) {
    prefix = m_buffer.toString();
    if (m_buffer.length() > 1) {
      m_repeatingChar = 0;
      searchStartOffset = 0;
    } else {
      m_repeatingChar = c;
    }
  }

  if (!prefix.isEmpty()) {
    int selected = m_dataSource->indexOfSelectedOption();
    int index = (selected < 0 ? 0 : selected) + searchStartOffset;
    index %= optionCount;

    // Compute a case-folded copy of the prefix string before beginning the
    // search for a matching element. This code uses foldCase to work around the
    // fact that String::startWith does not fold non-ASCII characters. This code
    // can be changed to use startWith once that is fixed.
    String prefixWithCaseFolded(prefix.foldCase());
    for (int i = 0; i < optionCount; ++i, index = (index + 1) % optionCount) {
      // Fold the option string and check if its prefix is equal to the folded
      // prefix.
      String text = m_dataSource->optionAtIndex(index);
      if (stripLeadingWhiteSpace(text).foldCase().startsWith(
              prefixWithCaseFolded))
        return index;
    }
  }

  if (matchMode & MatchIndex) {
    bool ok = false;
    int index = m_buffer.toString().toInt(&ok);
    if (index > 0 && index <= optionCount)
      return index - 1;
  }
  return -1;
}

bool TypeAhead::hasActiveSession(KeyboardEvent* event) {
  double delta = event->platformTimeStamp() - m_lastTypeTime;
  return delta <= typeAheadTimeout;
}

void TypeAhead::resetSession() {
  m_lastTypeTime = 0;
  m_buffer.clear();
}

}  // namespace blink