/// <summary>
/// Visits and evaluates relational operator expression.
/// </summary>
/// <param name="expression">Relational operator expression.</param>
/// <returns>True if the specified expression evaluates as true, false otherwise.</returns>
public bool Visit(NumericCompareExpression expression)
{
double leftValue = NumericEvaluator.Value.Evaluate(expression.LeftArgument, Substitution, ReferenceState);
double rightValue = NumericEvaluator.Value.Evaluate(expression.RightArgument, Substitution, ReferenceState);
return(NumericCompareExpression.ApplyCompare(expression.Operator, leftValue, rightValue));
}
/// <summary>
/// Evaluates the expression.
/// </summary>
/// <param name="expression">Expression.</param>
/// <returns>True if the expression is logically true, false otherwise.</returns>
public bool Visit(NumericCompareLiteralCNF expression)
{
double leftValue = NumericEvaluator.Value.Evaluate(expression.LeftArgument, Substitution, ReferenceState);
double rightValue = NumericEvaluator.Value.Evaluate(expression.RightArgument, Substitution, ReferenceState);
bool evaluationResult = NumericCompareExpression.ApplyCompare(expression.Operator, leftValue, rightValue);
return(!expression.IsNegated == evaluationResult);
}
/// <summary>
/// Visits the expression.
/// </summary>
/// <param name="expression">Expression.</param>
public IElementCNF Visit(NumericCompareLiteralCNF expression)
{
// 1.) Evaluates both of the arguments by NumericAssignmentsBackwardsReplacer - every numeric function instance is replaced by
// the available numeric assignments from effects and the whole numeric expression is reduced (partially or fully evaluated).
// 2.) In case of the full reduction of both arguments, the numeric comparison is evaluated - if successfully, the whole condition
// is satisfied and we can remove it (i.e. return null).
// 3.) Otherwise, the modified numeric compare expression is returned, replacing the original condition.
var numericAssignEffects = Effects.GroundedNumericFunctionAssignmentEffects;
if (numericAssignEffects.Count == 0)
{
// no assignment effects available, just return a copy of the original expression
return(expression.Clone());
}
NumericAssignmentsBackwardsReplacer replacer = new NumericAssignmentsBackwardsReplacer(numericAssignEffects, GroundingManager, OperatorSubstitution, ExpressionSubstitution);
INumericExpression newLeftNumericExpression = replacer.Replace(expression.LeftArgument);
INumericExpression newRightNumericExpression = replacer.Replace(expression.RightArgument);
UsedGroundedFunctions.UnionWith(replacer.ReplacedFunctionAtomsInSubExpression);
Number leftNumber = newLeftNumericExpression as Number;
Number rightNumber = newRightNumericExpression as Number;
if (leftNumber != null && rightNumber != null)
{
bool relationHolds = NumericCompareExpression.ApplyCompare(expression.Operator, leftNumber.Value, rightNumber.Value);
if ((relationHolds && !expression.IsNegated) || (!relationHolds && expression.IsNegated))
{
// the numeric comparison was successful -> condition is satisfied, i.e. remove
return(null);
}
}
// modified numeric compare expression, replacing the original one
return(new NumericCompareLiteralCNF(expression.Operator, newLeftNumericExpression, newRightNumericExpression, expression.IsNegated));
}
