/// <summary>
/// Combine all the IConstraints in only one IConstraint.
/// </summary>
/// <param name="expression">The expression, in the form of a list
/// of IConstraint in a postfix expression form</param>
/// <returns></returns>
public IConstraint ResolveExpression(IList <IConstraint> expression)
{
Stack <IConstraint> stack = new Stack <IConstraint>();
StringBuilder errors = new StringBuilder();
foreach (IConstraint IConstraint in expression)
{
if (IConstraint is BinaryConstraint)
{
BinaryConstraint binop = IConstraint as BinaryConstraint;
IConstraint right = stack.Pop();
IConstraint left = stack.Pop();
stack.Push(binop.SetConstraint(left, right));
}
else if (IConstraint is UnaryConstraint)
{
Debug.Assert(stack.Count > 0, "trying to apply an unary IConstraint on a null object");
UnaryConstraint unop = IConstraint as UnaryConstraint;
stack.Push(unop.SetConstraint(stack.Pop()));
}
else
{
stack.Push(IConstraint);
}
}
return(stack.Pop());
}
private Constraint GenerateUnary(int varId, int value, int index)
{
Constraint result = new UnaryConstraint <Permutation>()
{
Check = () => Variables[varId].Current == null || Variables[varId].Current.Values[index] == value,
Variable = Variables[varId]
};
return(result);
}
