/*

 * Copyright 2005 Frerich Raabe <raabe@kde.org>

 * Copyright (C) 2006 Apple Computer, Inc.

 * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.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.

 */

#include "config.h"

#if ENABLE(XPATH)

#include "XPathPredicate.h"

#include "Node.h"

#include "XPathFunctions.h"

#include "XPathUtil.h"

#include "XPathValue.h"

#include <math.h>

#include <wtf/MathExtras.h>

namespace WebCore {

namespace XPath {

Number::Number(double value)

    : m_value(value)

{

}

Value Number::evaluate() const

{

    return m_value;

}

StringExpression::StringExpression(const String& value)

    : m_value(value)

{

}

Value StringExpression::evaluate() const

{

    return m_value;

}

Value Negative::evaluate() const

{

    Value p(subExpr(0)->evaluate());

    return -p.toNumber();

}

NumericOp::NumericOp(Opcode opcode, Expression* lhs, Expression* rhs)

    : m_opcode(opcode)

{

    addSubExpression(lhs);

    addSubExpression(rhs);

}

Value NumericOp::evaluate() const

{

    Value lhs(subExpr(0)->evaluate());

    Value rhs(subExpr(1)->evaluate());

    double leftVal = lhs.toNumber();

    double rightVal = rhs.toNumber();

    switch (m_opcode) {

        case OP_Add:

            return leftVal + rightVal;

        case OP_Sub:

            return leftVal - rightVal;

        case OP_Mul:

            return leftVal * rightVal;

        case OP_Div:

            return leftVal / rightVal;

        case OP_Mod:

            return fmod(leftVal, rightVal);

    }

    ASSERT_NOT_REACHED();

    return 0.0;

}

EqTestOp::EqTestOp(Opcode opcode, Expression* lhs, Expression* rhs)

    : m_opcode(opcode)

{

    addSubExpression(lhs);

    addSubExpression(rhs);

}

bool EqTestOp::compare(const Value& lhs, const Value& rhs) const

{

    if (lhs.isNodeSet()) {

        const NodeSet& lhsSet = lhs.toNodeSet();

        if (rhs.isNodeSet()) {

            // If both objects to be compared are node-sets, then the comparison will be true if and only if

            // there is a node in the first node-set and a node in the second node-set such that the result of

            // performing the comparison on the string-values of the two nodes is true.

            const NodeSet& rhsSet = rhs.toNodeSet();

            for (unsigned lindex = 0; lindex < lhsSet.size(); ++lindex)

                for (unsigned rindex = 0; rindex < rhsSet.size(); ++rindex)

                    if (compare(stringValue(lhsSet[lindex]), stringValue(rhsSet[rindex])))

                        return true;

            return false;

        }

        if (rhs.isNumber()) {

            // If one object to be compared is a node-set and the other is a number, then the comparison will be true

            // if and only if there is a node in the node-set such that the result of performing the comparison on the number

            // to be compared and on the result of converting the string-value of that node to a number using the number function is true.

            for (unsigned lindex = 0; lindex < lhsSet.size(); ++lindex)

                if (compare(Value(stringValue(lhsSet[lindex])).toNumber(), rhs))

                    return true;

            return false;

        }

        if (rhs.isString()) {

            // If one object to be compared is a node-set and the other is a string, then the comparison will be true

            // if and only if there is a node in the node-set such that the result of performing the comparison on

            // the string-value of the node and the other string is true.

            for (unsigned lindex = 0; lindex < lhsSet.size(); ++lindex)

                if (compare(stringValue(lhsSet[lindex]), rhs))

                    return true;

            return false;

        }

        if (rhs.isBoolean()) {

            // If one object to be compared is a node-set and the other is a boolean, then the comparison will be true

            // if and only if the result of performing the comparison on the boolean and on the result of converting

            // the node-set to a boolean using the boolean function is true.

            return compare((unsigned long)(lhs.toBoolean()), rhs);

        }

        ASSERT(0);

    }

    if (rhs.isNodeSet()) {

        const NodeSet& rhsSet = rhs.toNodeSet();

        if (lhs.isNumber()) {

            for (unsigned rindex = 0; rindex < rhsSet.size(); ++rindex)

                if (compare(lhs, Value(stringValue(rhsSet[rindex])).toNumber()))

                    return true;

            return false;

        }

        if (lhs.isString()) {

            for (unsigned rindex = 0; rindex < rhsSet.size(); ++rindex)

                if (compare(lhs, stringValue(rhsSet[rindex])))

                    return true;

            return false;

        }

        if (lhs.isBoolean())

            return compare(lhs, (unsigned long)(rhs.toBoolean()));

        ASSERT(0);

    }

    // Neither side is a NodeSet.

    switch (m_opcode) {

        case OP_EQ:

        case OP_NE:

            bool equal;

            if (lhs.isBoolean() || rhs.isBoolean())

                equal = lhs.toBoolean() == rhs.toBoolean();

            else if (lhs.isNumber() || rhs.isNumber())

                equal = lhs.toNumber() == rhs.toNumber();

            else

                equal = lhs.toString() == rhs.toString();

            if (m_opcode == OP_EQ)

                return equal;

            return !equal;

        case OP_GT:

            return lhs.toNumber() > rhs.toNumber();

        case OP_GE:

            return lhs.toNumber() >= rhs.toNumber();

        case OP_LT:

            return lhs.toNumber() < rhs.toNumber();

        case OP_LE:

            return lhs.toNumber() <= rhs.toNumber();

    }

    ASSERT(0);

    return false;

}

Value EqTestOp::evaluate() const

{

    Value lhs(subExpr(0)->evaluate());

    Value rhs(subExpr(1)->evaluate());

    return (unsigned long)compare(lhs, rhs);

}

LogicalOp::LogicalOp(Opcode opcode, Expression* lhs, Expression* rhs)

    : m_opcode(opcode)

{

    addSubExpression(lhs);

    addSubExpression(rhs);

}

bool LogicalOp::shortCircuitOn() const

{

    if (m_opcode == OP_And)

        return false; //false and foo

    return true;  //true or bar

}

Value LogicalOp::evaluate() const

{

    Value lhs(subExpr(0)->evaluate());

    // This is not only an optimization, http://www.w3.org/TR/xpath

    // dictates that we must do short-circuit evaluation

    bool lhsBool = lhs.toBoolean();

    if (lhsBool == shortCircuitOn())

        return (unsigned long)lhsBool;

    return (unsigned long)(subExpr(1)->evaluate().toBoolean());

}

Value Union::evaluate() const

{

    Value lhsResult = subExpr(0)->evaluate();

    Value rhs = subExpr(1)->evaluate();

    NodeSet& resultSet = lhsResult.modifiableNodeSet();

    const NodeSet& rhsNodes = rhs.toNodeSet();

    HashSet<Node*> nodes;

    for (size_t i = 0; i < resultSet.size(); ++i)

        nodes.add(resultSet[i]);

    for (size_t i = 0; i < rhsNodes.size(); ++i) {

        Node* node = rhsNodes[i];

        if (nodes.add(node).second)

            resultSet.append(node);

    }

    // It is also possible to use merge sort to avoid making the result unsorted;

    // but this would waste the time in cases when order is not important.

    resultSet.markSorted(false);

    return lhsResult;

}

Predicate::Predicate(Expression* expr)

    : m_expr(expr)

{

}

Predicate::~Predicate()

{

    delete m_expr;

}

bool Predicate::evaluate() const

{

    ASSERT(m_expr != 0);

    Value result(m_expr->evaluate());

    // foo[3] means foo[position()=3]

    if (result.isNumber())

        return EqTestOp(EqTestOp::OP_EQ, createFunction("position"), new Number(result.toNumber())).evaluate().toBoolean();

    return result.toBoolean();

}

}

}

#endif // ENABLE(XPATH)