bidiresolver.h

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (C) 2000 Lars Knoll ([e-mail])
 * Copyright (C) 2003, 2004, 2006, 2007, 2008 Apple Inc.  All right 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.
 *
 */

#ifndef BidiResolver_h
#define BidiResolver_h

#include "BidiContext.h"
#include <wtf/Noncopyable.h>
#include <wtf/PassRefPtr.h>
#include <wtf/Vector.h>

namespace WebCore {

// The BidiStatus at a given position (typically the end of a line) can
// be cached and then used to restart bidi resolution at that position.
struct BidiStatus {
    BidiStatus()
        : eor(WTF::Unicode::OtherNeutral)
        , lastStrong(WTF::Unicode::OtherNeutral)
        , last(WTF::Unicode::OtherNeutral)
    {
    }

    BidiStatus(WTF::Unicode::Direction eorDir, WTF::Unicode::Direction lastStrongDir, WTF::Unicode::Direction lastDir, PassRefPtr<BidiContext> bidiContext)
        : eor(eorDir)
        , lastStrong(lastStrongDir)
        , last(lastDir)
        , context(bidiContext)
    {
    }

    WTF::Unicode::Direction eor;
    WTF::Unicode::Direction lastStrong;
    WTF::Unicode::Direction last;
    RefPtr<BidiContext> context;
};

inline bool operator==(const BidiStatus& status1, const BidiStatus& status2)
{
    return status1.eor == status2.eor && status1.last == status2.last && status1.lastStrong == status2.lastStrong && *(status1.context) == *(status2.context);
}

inline bool operator!=(const BidiStatus& status1, const BidiStatus& status2)
{
    return !(status1 == status2);
}

struct BidiCharacterRun {
    BidiCharacterRun(int start, int stop, BidiContext* context, WTF::Unicode::Direction dir)
        : m_start(start)
        , m_stop(stop)
        , m_override(context->override())
        , m_next(0)
    {
        if (dir == WTF::Unicode::OtherNeutral)
            dir = context->dir();

        m_level = context->level();

        // add level of run (cases I1 & I2)
        if (m_level % 2) {
            if (dir == WTF::Unicode::LeftToRight || dir == WTF::Unicode::ArabicNumber || dir == WTF::Unicode::EuropeanNumber)
                m_level++;
        } else {
            if (dir == WTF::Unicode::RightToLeft)
                m_level++;
            else if (dir == WTF::Unicode::ArabicNumber || dir == WTF::Unicode::EuropeanNumber)
                m_level += 2;
        }
    }

    void destroy() { delete this; }

    int start() const { return m_start; }
    int stop() const { return m_stop; }
    unsigned char level() const { return m_level; }
    bool reversed(bool visuallyOrdered) { return m_level % 2 && !visuallyOrdered; }
    bool dirOverride(bool visuallyOrdered) { return m_override || visuallyOrdered; }

    BidiCharacterRun* next() const { return m_next; }

    unsigned char m_level;
    int m_start;
    int m_stop;
    bool m_override;
    BidiCharacterRun* m_next;
};

template <class Iterator, class Run> class BidiResolver : public Noncopyable {
public :
    BidiResolver()
        : m_direction(WTF::Unicode::OtherNeutral)
        , reachedEndOfLine(false)
        , emptyRun(true)
        , m_firstRun(0)
        , m_lastRun(0)
        , m_logicallyLastRun(0)
        , m_runCount(0)
    {
    }

    const Iterator& position() const { return current; }
    void setPosition(const Iterator& position) { current = position; }

    void increment() { current.increment(); }

    BidiContext* context() const { return m_status.context.get(); }
    void setContext(PassRefPtr<BidiContext> c) { m_status.context = c; }

    void setLastDir(WTF::Unicode::Direction lastDir) { m_status.last = lastDir; }
    void setLastStrongDir(WTF::Unicode::Direction lastStrongDir) { m_status.lastStrong = lastStrongDir; }
    void setEorDir(WTF::Unicode::Direction eorDir) { m_status.eor = eorDir; }

    WTF::Unicode::Direction dir() const { return m_direction; }
    void setDir(WTF::Unicode::Direction d) { m_direction = d; }

    const BidiStatus& status() const { return m_status; }
    void setStatus(const BidiStatus s) { m_status = s; }

    void embed(WTF::Unicode::Direction);
    void commitExplicitEmbedding();

    void createBidiRunsForLine(const Iterator& end, bool visualOrder = false, bool hardLineBreak = false);

    Run* firstRun() const { return m_firstRun; }
    Run* lastRun() const { return m_lastRun; }
    Run* logicallyLastRun() const { return m_logicallyLastRun; }
    unsigned runCount() const { return m_runCount; }

    void addRun(Run*);
    void prependRun(Run*);

    void moveRunToEnd(Run*);
    void moveRunToBeginning(Run*);

    void deleteRuns();

protected:
    void appendRun();
    void reverseRuns(unsigned start, unsigned end);

    Iterator current;
    Iterator sor;
    Iterator eor;
    Iterator last;
    BidiStatus m_status;
    WTF::Unicode::Direction m_direction;
    Iterator endOfLine;
    bool reachedEndOfLine;
    Iterator lastBeforeET;
    bool emptyRun;

    Run* m_firstRun;
    Run* m_lastRun;
    Run* m_logicallyLastRun;
    unsigned m_runCount;

private:
    void raiseExplicitEmbeddingLevel(WTF::Unicode::Direction from, WTF::Unicode::Direction to);
    void lowerExplicitEmbeddingLevel(WTF::Unicode::Direction from);

    Vector<WTF::Unicode::Direction, 8> m_currentExplicitEmbeddingSequence;
};

template <class Iterator, class Run>
inline void BidiResolver<Iterator, Run>::addRun(Run* run)
{
    if (!m_firstRun)
        m_firstRun = run;
    else
        m_lastRun->m_next = run;
    m_lastRun = run;
    m_runCount++;
}

template <class Iterator, class Run>
inline void BidiResolver<Iterator, Run>::prependRun(Run* run)
{
    ASSERT(!run->m_next);

    if (!m_lastRun)
        m_lastRun = run;
    else
        run->m_next = m_firstRun;
    m_firstRun = run;
    m_runCount++;
}

template <class Iterator, class Run>
inline void BidiResolver<Iterator, Run>::moveRunToEnd(Run* run)
{
    ASSERT(m_firstRun);
    ASSERT(m_lastRun);
    ASSERT(run->m_next);

    Run* current = 0;
    Run* next = m_firstRun;
    while (next != run) {
        current = next;
        next = current->next();
    }

    if (!current)
        m_firstRun = run->next();
    else
        current->m_next = run->m_next;

    run->m_next = 0;
    m_lastRun->m_next = run;
    m_lastRun = run;
}

template <class Iterator, class Run>
inline void BidiResolver<Iterator, Run>::moveRunToBeginning(Run* run)
{
    ASSERT(m_firstRun);
    ASSERT(m_lastRun);
    ASSERT(run != m_firstRun);

    Run* current = m_firstRun;
    Run* next = current->next();
    while (next != run) {
        current = next;
        next = current->next();
    }

    current->m_next = run->m_next;
    if (run == m_lastRun)
        m_lastRun = current;

    run->m_next = m_firstRun;
    m_firstRun = run;
}

template <class Iterator, class Run>
void BidiResolver<Iterator, Run>::appendRun()
{
    if (!emptyRun && !eor.atEnd()) {
        addRun(new Run(sor.offset(), eor.offset() + 1, context(), m_direction));

        eor.increment();
        sor = eor;
    }

    m_direction = WTF::Unicode::OtherNeutral;
    m_status.eor = WTF::Unicode::OtherNeutral;
}

template <class Iterator, class Run>
void BidiResolver<Iterator, Run>::embed(WTF::Unicode::Direction d)
{
    using namespace WTF::Unicode;

    ASSERT(d == PopDirectionalFormat || d == LeftToRightEmbedding || d == LeftToRightOverride || d == RightToLeftEmbedding || d == RightToLeftOverride);
    m_currentExplicitEmbeddingSequence.append(d);
}

template <class Iterator, class Run>
void BidiResolver<Iterator, Run>::lowerExplicitEmbeddingLevel(WTF::Unicode::Direction from)
{
    using namespace WTF::Unicode;

    if (!emptyRun && eor != last) {
        ASSERT(m_status.eor != OtherNeutral || eor.atEnd());
        // bidi.sor ... bidi.eor ... bidi.last eor; need to append the bidi.sor-bidi.eor run or extend it through bidi.last
        ASSERT(m_status.last == EuropeanNumberSeparator
            || m_status.last == EuropeanNumberTerminator
            || m_status.last == CommonNumberSeparator
            || m_status.last == BoundaryNeutral
            || m_status.last == BlockSeparator
            || m_status.last == SegmentSeparator
            || m_status.last == WhiteSpaceNeutral
            || m_status.last == OtherNeutral);
        if (m_direction == OtherNeutral)
            m_direction = m_status.lastStrong == LeftToRight ? LeftToRight : RightToLeft;
        if (from == LeftToRight) {
            // bidi.sor ... bidi.eor ... bidi.last L
            if (m_status.eor == EuropeanNumber) {
                if (m_status.lastStrong != LeftToRight) {
                    m_direction = EuropeanNumber;
                    appendRun();
                }
            } else if (m_status.eor == ArabicNumber) {
                m_direction = ArabicNumber;
                appendRun();
            } else if (m_status.lastStrong != LeftToRight) {
                appendRun();
                m_direction = LeftToRight;
            }
        } else if (m_status.eor == EuropeanNumber || m_status.eor == ArabicNumber || m_status.lastStrong == LeftToRight) {
            appendRun();
            m_direction = RightToLeft;
        }
        eor = last;
    }