source: trunk/src/xmlpatterns/data/qatomiccomparator_p.h@ 1036

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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_AtomicComparator_H
#define Patternist_AtomicComparator_H

#include <QFlags>

#include "qitem_p.h"
#include "qatomictypedispatch_p.h"

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

class QString;

namespace QPatternist
{

    /**
     * @short Base class for classes responsible of comparing two atomic values.
     *
     * This class is also known as the AtomicParrot.
     *
     * @ingroup Patternist_xdm
     * @author Frans Englich <[email protected]>
     */
    class Q_AUTOTEST_EXPORT AtomicComparator : public AtomicTypeVisitorResult
    {
    public:
        AtomicComparator();
        virtual ~AtomicComparator();

        typedef QExplicitlySharedDataPointer<AtomicComparator> Ptr;

        /**
         * Identifies operators used in value comparisons.
         *
         * The enum values are bit-significant.
         *
         * @see <a href="http://www.w3.org/TR/xpath20/#id-value-comparisons">W3C XML Path
         * Language (XPath) 2.0, 3.5.1 Value Comparisons</a>
         */
        enum Operator
        {
            /**
             * Operator <tt>eq</tt> and <tt>=</tt>.
             */
            OperatorEqual           = 1,

            /**
             * Operator <tt>ne</tt> and <tt>!=</tt>.
             */
            OperatorNotEqual        = 1 << 1,

            /**
             * Operator <tt>gt</tt> and <tt>\></tt>.
             */
            OperatorGreaterThan     = 1 << 2,

            /**
             * Operator <tt>lt</tt> and <tt>\<</tt>.
             */
            OperatorLessThan        = 1 << 3,

            /**
             * One of the operators we use for sorting. The only difference from
             * OperatorLessThan is that it sees NaN as ordered and smaller than
             * other numbers.
             */
            OperatorLessThanNaNLeast    = 1 << 4,

            /**
             * One of the operators we use for sorting. The only difference from
             * OperatorLessThanLeast is that it sees NaN as ordered and larger than
             * other numbers.