public UnaryLtlExpression(UnaryLtlOperator op, LtlExpression operand)
{
Operator = op;
Operand = operand;
}
public BinaryLtlExpression(BinaryLtlOperator op, LtlExpression lhs, LtlExpression rhs)
{
Operator = op;
LhsOperand = lhs;
RhsOperand = rhs;
}
/// <summary>
/// Evaluates whether expression holds for the case.
/// The main idea taken from https://link.springer.com/content/pdf/10.1007%2F11575771_11.pdf
/// </summary>
/// <param name="events">Sorted list of event in a case.</param>
/// <param name="expression">Expression to be evaluated.</param>
/// <param name="position">Starting position from which we start the evaluation.</param>
/// <returns>Bool whether expression holds.</returns>
/// <exception cref="ArgumentOutOfRangeException">Expression contains undefined operator.</exception>
public bool EvaluateExpression(List <Event> events, LtlExpression expression, int position = 0)
{
if (position >= events.Count)
{
return(false);
}
switch (expression.Operator)
{
case Operators.None:
return(events[position].Activity == expression.Atom);
case Operators.Not:
return(!EvaluateExpression(events, expression.InnerLeft, position));
case Operators.Next:
if (position >= 0 && position < events.Count - 1)
{
return(EvaluateExpression(events, expression.InnerLeft, position + 1));
}
return(false);
case Operators.Subsequent:
if (position >= 0 && position < events.Count - 1)
{
return(EvaluateExpression(events, expression.InnerLeft, position) &&
EvaluateExpression(events, expression, position + 1));
}
return(EvaluateExpression(events, expression.InnerLeft, position));
case Operators.Eventual:
if (position >= 0 && position < events.Count - 1)
{
return(EvaluateExpression(events, expression.InnerLeft, position) ||
EvaluateExpression(events, expression, position + 1));
}
return(EvaluateExpression(events, expression.InnerLeft, position));
case Operators.And:
return(EvaluateExpression(events, expression.InnerLeft, position) &&
EvaluateExpression(events, expression.InnerRight, position));
case Operators.Or:
return(EvaluateExpression(events, expression.InnerLeft, position) ||
EvaluateExpression(events, expression.InnerRight, position));
case Operators.Imply:
return(!EvaluateExpression(events, expression.InnerLeft, position) ||
EvaluateExpression(events, expression.InnerRight, position));
case Operators.Equivalence:
var a = EvaluateExpression(events, expression.InnerLeft, position);
var b = EvaluateExpression(events, expression.InnerRight, position);
return(a && b || !a && !b);
case Operators.Least:
if (position >= 0 && position < events.Count - 1)
{
return(EvaluateExpression(events, expression.InnerRight, position) ||
EvaluateExpression(events, expression.InnerLeft, position) &&
EvaluateExpression(events, expression, position + 1));
}
return(EvaluateExpression(events, expression.InnerLeft, position) ||
EvaluateExpression(events, expression.InnerRight, position));
default:
throw new ArgumentOutOfRangeException();
}
}