predicate.h

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/*
 * predicate.h - Copyright 2005 Frerich Raabe <raabe@kde.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef PREDICATE_H
#define PREDICATE_H

#include "expression.h"

namespace khtml {
namespace XPath {

class Number : public Expression
{
    public:
        Number( double value );

        bool isConstant() const;
        virtual QString dump() const;

    private:
        virtual Value doEvaluate() const;

        double m_value;
};

class String : public Expression
{
    public:
        String( const DOM::DOMString &value );

        bool isConstant() const;
        virtual QString dump() const;

    private:
        virtual Value doEvaluate() const;

        DOM::DOMString m_value;
};

class Negative : public Expression
{
    public:
        virtual QString dump() const;

    private:
        virtual Value doEvaluate() const;
};

class BinaryExprBase : public Expression
{
    public:
        virtual QString dump() const;

    protected:
        virtual QString opName() const = 0;
};

class NumericOp : public BinaryExprBase
{
    public:
        enum {
            OP_Add = 1,
            OP_Sub,
            OP_Mul,
            OP_Div,
            OP_Mod
        };

        NumericOp( int opCode, Expression* lhs, Expression* rhs );

    private:
        virtual QString opName() const;
        virtual Value doEvaluate() const;
        int opCode;
};

class RelationOp : public BinaryExprBase
{
    public:
        enum {
            OP_GT = 1,
            OP_LT,
            OP_GE,
            OP_LE,
            OP_EQ,
            OP_NE           
        };

        RelationOp( int opCode, Expression* lhs, Expression* rhs );

    private:
        virtual QString opName() const;
        virtual Value doEvaluate() const;
        int opCode;

        // compares strings based on the op-code
        bool compareStrings(const DOM::DOMString& l, const DOM::DOMString& r) const;
        bool compareNumbers(double l, double r) const;
};

class LogicalOp : public BinaryExprBase
{
    public:
        enum {
            OP_And = 1,
            OP_Or
        };

        LogicalOp( int opCode, Expression* lhs, Expression* rhs );

        virtual bool isConstant() const;

    private:
        bool    shortCircuitOn() const;
        virtual QString opName() const;
        virtual Value doEvaluate() const;
        int opCode;
};

class Union : public BinaryExprBase
{
    private:
        virtual QString opName() const;
        virtual Value doEvaluate() const;
};

class Predicate
{
    public:
        Predicate( Expression *expr );
        ~Predicate();

        bool evaluate() const;

        void optimize();
        QString dump() const;

    private:
        Predicate( const Predicate &rhs );
        Predicate &operator=( const Predicate &rhs );

        Expression *m_expr;
};

} // namespace XPath

} // namespace khtml


#endif // PREDICATE_H

// kate: indent-width 4; replace-tabs off; tab-width 4; space-indent off;