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/*
* Copyright (C) Research In Motion Limited 2011. All rights reserved.
*
* 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.
*
*/
#pragma once
#include <unicode/utf16.h>
#include <wtf/text/WTFString.h>
namespace WebCore {
class SurrogatePairAwareTextIterator {
public:
// The passed in UChar pointer starts at 'currentIndex'. The iterator operates on the range [currentIndex, lastIndex].
// 'endIndex' denotes the maximum length of the UChar array, which might exceed 'lastIndex'.
SurrogatePairAwareTextIterator(std::span<const UChar> characters, unsigned currentIndex, unsigned lastIndex)
: m_characters(characters)
, m_currentIndex(currentIndex)
, m_originalIndex(currentIndex)
, m_lastIndex(lastIndex)
, m_endIndex(characters.size() + currentIndex)
{
}
bool consume(char32_t& character, unsigned& clusterLength)
{
if (m_currentIndex >= m_lastIndex)
return false;
auto relativeIndex = m_currentIndex - m_originalIndex;
clusterLength = 0;
auto spanAtRelativeIndex = m_characters.subspan(relativeIndex);
U16_NEXT(spanAtRelativeIndex, clusterLength, m_endIndex - m_currentIndex, character);
return true;
}
void advance(unsigned advanceLength)
{
m_currentIndex += advanceLength;
}
void reset(unsigned index)
{
if (index >= m_lastIndex)
return;
m_currentIndex = index;
}
std::span<const UChar> remainingCharacters() const
{
auto relativeIndex = m_currentIndex - m_originalIndex;
return m_characters.subspan(relativeIndex);
}
unsigned currentIndex() const { return m_currentIndex; }
std::span<const UChar> characters() const { return m_characters; }
private:
std::span<const UChar> m_characters;
unsigned m_currentIndex { 0 };
const unsigned m_originalIndex { 0 };
const unsigned m_lastIndex { 0 };
const unsigned m_endIndex { 0 };
};
} // namespace WebCore
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