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// Copyright Joakim Karlsson & Kim Gräsman 2010-2012.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef IGLOO_CONTRAINTOPERATOR_H
#define IGLOO_CONTRAINTOPERATOR_H
namespace snowhouse {
struct InvalidExpressionException
{
InvalidExpressionException(const std::string& message) : m_message(message)
{
}
const std::string& Message() const
{
return m_message;
}
std::string m_message;
};
struct ConstraintOperator
{
virtual ~ConstraintOperator() {}
virtual void PerformOperation(ResultStack& result) = 0;
virtual int Precedence() const = 0;
template <typename ConstraintListType, typename ActualType>
static bool EvaluateElementAgainstRestOfExpression(ConstraintListType& list, const ActualType& actual)
{
ResultStack innerResult;
OperatorStack innerOperators;
EvaluateConstraintList(list.m_tail, innerResult, innerOperators, actual);
EvaluateAllOperatorsOnStack(innerOperators, innerResult);
if(innerResult.empty())
{
throw InvalidExpressionException("The expression after \"" + snowhouse::Stringize(list.m_head) + "\" operator does not yield any result");
}
return innerResult.top();
}
static void EvaluateOperatorsWithLessOrEqualPrecedence(const ConstraintOperator& op, OperatorStack& operators, ResultStack& result)
{
while(!operators.empty())
{
ConstraintOperator* op_from_stack = operators.top();
if(op_from_stack->Precedence() > op.Precedence())
{
break;
}
op_from_stack->PerformOperation(result);
operators.pop();
}
}
static void EvaluateAllOperatorsOnStack(OperatorStack& operators, ResultStack& result)
{
while(!operators.empty())
{
ConstraintOperator* op = operators.top();
op->PerformOperation(result);
operators.pop();
}
}
};
}
#endif
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