arabica/include/XPath/impl/xpath_logical.hpp
jez 235f81718d Added Expression_scanner and scan (a visitor pattern basically) to allow XPathExpression_impls to be examined. This is used in the match rewriting to search for position() and last() function calls.
To ease implementing scan, BinaryExpression and UnaryExpression now inherit XPathExpression_impl.  Other classes now derived only from Binary|UnaryExpression rather than from XPathExpression_impl as well.
2007-12-21 15:56:04 +00:00

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2.9 KiB
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#ifndef ARABICA_XPATHIC_XPATH_LOGICAL_HPP
#define ARABICA_XPATHIC_XPATH_LOGICAL_HPP
#include "xpath_value.hpp"
namespace Arabica
{
namespace XPath
{
namespace impl
{
template<class string_type, class string_adaptor>
class OrOperator : public BinaryExpression<string_type, string_adaptor>
{
typedef BinaryExpression<string_type, string_adaptor> baseT;
public:
OrOperator(XPathExpression_impl<string_type, string_adaptor>* lhs,
XPathExpression_impl<string_type, string_adaptor>* rhs) :
BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
virtual ValueType type() const { return BOOL; }
virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context,
const ExecutionContext<string_type, string_adaptor>& executionContext) const
{
// From XPath 1.0 Rec, section 3.4
// An or expression is evaluated by evaluating each operand and converting its value
// to a boolean as if by a call to the boolean function. The result is true if either
// value is true and false otherwise. The right operand is not evaluated if the
// left operand evaluates to true.
if(baseT::lhs()->evaluate(context, executionContext).asBool())
return BoolValue<string_type, string_adaptor>::createValue(true);
return BoolValue<string_type, string_adaptor>::createValue(baseT::rhs()->evaluate(context, executionContext).asBool());
} // evaluate
}; // class OrOperator
template<class string_type, class string_adaptor>
class AndOperator : public BinaryExpression<string_type, string_adaptor>
{
typedef BinaryExpression<string_type, string_adaptor> baseT;
public:
AndOperator(XPathExpression_impl<string_type, string_adaptor>* lhs,
XPathExpression_impl<string_type, string_adaptor>* rhs) :
BinaryExpression<string_type, string_adaptor>(lhs, rhs) { }
virtual ValueType type() const { return BOOL; }
virtual XPathValue<string_type, string_adaptor> evaluate(const DOM::Node<string_type, string_adaptor>& context,
const ExecutionContext<string_type, string_adaptor>& executionContext) const
{
// From XPath 1.0 Rec, section 3.4
// An and expression is evaluated by evaluating each operand and converting its value
// to a boolean as if by a call to the boolean function. The result is true if both
// values are true and false otherwise. The right operand is not evaluated if the left
// operand evaluates to false.
if(!baseT::lhs()->evaluate(context, executionContext).asBool())
return BoolValue<string_type, string_adaptor>::createValue(false);
return BoolValue<string_type, string_adaptor>::createValue(baseT::rhs()->evaluate(context, executionContext).asBool());
} // evaluate
}; // class AndOperator
} // namespace impl
} // namespace XPath
} // namespace Arabica
#endif