Source/WebCore/editing/SurroundingText.cpp

/*
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#include "config.h"
#include "SurroundingText.h"

#include "Document.h"
#include "Range.h"
#include "TextIterator.h"
#include "VisiblePosition.h"
#include "VisibleSelection.h"
#include "visible_units.h"

namespace WebCore {

SurroundingText::SurroundingText(const VisiblePosition& visiblePosition, unsigned maxLength)
    : m_positionOffsetInContent(0)
{
    if (visiblePosition.isNull())
        return;

    const unsigned halfMaxLength = maxLength / 2;
    CharacterIterator forwardIterator(makeRange(visiblePosition, endOfDocument(visiblePosition)).get(), TextIteratorStopsOnFormControls);
    if (!forwardIterator.atEnd())
        forwardIterator.advance(maxLength - halfMaxLength);

    Position position = visiblePosition.deepEquivalent().parentAnchoredEquivalent();
    Document* document = position.document();
    RefPtr<Range> forwardRange = forwardIterator.range();
    if (!forwardRange || !Range::create(document, position, forwardRange->startPosition())->text().length()) {
        ASSERT(forwardRange);
        return;
    }

    BackwardsCharacterIterator backwardsIterator(makeRange(startOfDocument(visiblePosition), visiblePosition).get(), TextIteratorStopsOnFormControls);
    if (!backwardsIterator.atEnd())
        backwardsIterator.advance(halfMaxLength);

    RefPtr<Range> backwardsRange = backwardsIterator.range();
    if (!backwardsRange) {
        ASSERT(backwardsRange);
        return;
    }

    m_positionOffsetInContent = Range::create(document, backwardsRange->endPosition(), position)->text().length();
    m_contentRange = Range::create(document, backwardsRange->endPosition(), forwardRange->startPosition());
    ASSERT(m_contentRange);
}

PassRefPtr<Range> SurroundingText::rangeFromContentOffsets(unsigned startOffsetInContent, unsigned endOffsetInContent)
{
    if (startOffsetInContent >= endOffsetInContent || endOffsetInContent > content().length())
        return 0;

    CharacterIterator iterator(m_contentRange.get());

    ASSERT(!iterator.atEnd());
    iterator.advance(startOffsetInContent);

    ASSERT(iterator.range());
    Position start = iterator.range()->startPosition();

    ASSERT(!iterator.atEnd());
    iterator.advance(endOffsetInContent - startOffsetInContent);

    ASSERT(iterator.range());
    Position end = iterator.range()->startPosition();

    return Range::create(start.document(), start, end);
}

String SurroundingText::content() const
{
    if (m_contentRange)
        return m_contentRange->text();
    return String();
}

unsigned SurroundingText::positionOffsetInContent() const
{
    return m_positionOffsetInContent;
}

} // namespace WebCore