qprojectedexpression_p.h

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//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.

#ifndef Patternist_ProjectedExpression_H
#define Patternist_ProjectedExpression_H

#include "qitem_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist
{
    class ProjectedExpression
    {
    public:
        typedef ProjectedExpression * Ptr;
        typedef QVector<ProjectedExpression::Ptr> Vector;
        virtual ~ProjectedExpression()
        {
        }

        enum Action
        {
            Move = 0,
            Skip = 1,
            Keep = 2,
            KeepSubtree = 4 | Keep
        };

        virtual Action actionForElement(const QXmlName name,
                                        ProjectedExpression::Ptr &next) const
        {
            Q_UNUSED(name);
            Q_UNUSED(next);
            return Skip;
        }

    };

    class ProjectedNodeTest
    {
    public:
        typedef ProjectedNodeTest * Ptr;
        virtual ~ProjectedNodeTest()
        {
        }

        virtual bool isMatch(const QXmlNodeModelIndex::NodeKind kind) const
        {
            Q_UNUSED(kind);
            return false;
        }
    };

    class ProjectedStep : public ProjectedExpression
    {
    public:
        ProjectedStep(const ProjectedNodeTest::Ptr test,
                      const QXmlNodeModelIndex::Axis axis) : m_test(test),
                                               m_axis(axis)
        {
            Q_ASSERT(m_test);
        }

        virtual Action actionForElement(const QXmlName name,
                                        ProjectedExpression::Ptr &next) const
        {
            Q_UNUSED(name);
            Q_UNUSED(next);
            // TODO
            return Skip;
        }

    private:
        const ProjectedNodeTest::Ptr    m_test;
        const QXmlNodeModelIndex::Axis                m_axis;
    };

    class ProjectedPath : public ProjectedExpression
    {
    public:
        ProjectedPath(const ProjectedExpression::Ptr left,
                      const ProjectedExpression::Ptr right) : m_left(left),
                                                              m_right(right)
        {
            Q_ASSERT(m_left);
            Q_ASSERT(m_right);
        }

        virtual Action actionForElement(const QXmlName name,
                                        ProjectedExpression::Ptr &next) const
        {
            ProjectedExpression::Ptr &candidateNext = next;
            const Action a = m_left->actionForElement(name, candidateNext);

            if(a != Skip)
            {
                /* The test accepted it, so let's replace us with the new step. */
                next = candidateNext;
            }

            return a;
        }

    private:
        const ProjectedExpression::Ptr  m_left;
        const ProjectedExpression::Ptr  m_right;
    };
}

QT_END_NAMESPACE

QT_END_HEADER

#endif