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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_ValueComparison_H

#define Patternist_ValueComparison_H

#include "qatomiccomparator_p.h"

#include "qpaircontainer_p.h"

#include "qcomparisonplatform_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

namespace QPatternist

{

    /**

     * @short Implements XPath 2.0 value comparions, such as the <tt>eq</tt> operator.

     *

     * ComparisonPlatform is inherited with @c protected scope because ComparisonPlatform

     * must access members of ValueComparison.

     *

     * @see <a href="http://www.w3.org/TR/xpath20/#id-value-comparisons">XML Path Language

     * (XPath) 2.0, 3.5.1 Value Comparisons</a>

     * @author Frans Englich <frans.englich@nokia.com>

     * @ingroup Patternist_expressions

     */

    class ValueComparison : public PairContainer,

                            public ComparisonPlatform<ValueComparison, true>

    {

    public:

        ValueComparison(const Expression::Ptr &op1,

                        const AtomicComparator::Operator op,

                        const Expression::Ptr &op2);

        virtual Item evaluateSingleton(const DynamicContext::Ptr &) const;

        virtual Expression::Ptr typeCheck(const StaticContext::Ptr &context,

                                          const SequenceType::Ptr &reqType);

        /**

         * @returns always CommonSequenceTypes::ExactlyOneBoolean

         */

        virtual SequenceType::Ptr staticType() const;

        virtual SequenceType::List expectedOperandTypes() const;

        /**

         * @returns IDValueComparison

         */

        virtual ID id() const;

        virtual ExpressionVisitorResult::Ptr accept(const ExpressionVisitor::Ptr &visitor) const;

        virtual QList<QExplicitlySharedDataPointer<OptimizationPass> > optimizationPasses() const;

        /**

         * Overridden to optimize case-insensitive compares.

         */

        virtual Expression::Ptr compress(const StaticContext::Ptr &context);

        /**

         * @returns the operator that this ValueComparison is using.

         */

        inline AtomicComparator::Operator operatorID() const

        {

            return m_operator;

        }

        /**

         * It is considered that the string value from @p op1 will be compared against @p op2. This

         * function determines whether the user intends the comparison to be case insensitive. If

         * that is the case @c true is returned, and the operands are re-written appropriately.

         *

         * This is a helper function for Expression classes that compares strings.

         *

         * @see ComparisonPlatform::useCaseInsensitiveComparator()

         */

        static bool isCaseInsensitiveCompare(Expression::Ptr &op1, Expression::Ptr &op2);

    private:

        const AtomicComparator::Operator m_operator;

    };

}

QT_END_NAMESPACE

QT_END_HEADER

#endif