public override VariableValue Evaluate(IVariableStore variables)
{
var left = Left.Evaluate(variables);
if (left.HasList)
{
var result = left.List.Count > 0 ? left.List.RemoveVariable(left.List.Count - 1) : SetVariableResult.NotFound;
if (result != SetVariableResult.Success)
{
switch (result)
{
case SetVariableResult.NotFound: throw new ExpressionEvaluationException(_missingRemoveException, Left);
case SetVariableResult.ReadOnly: throw new ExpressionEvaluationException(_readOnlyRemoveException, Left);
case SetVariableResult.TypeMismatch: throw new ExpressionEvaluationException(_mismatchedRemoveException, Left);
}
}
return(left);
}
else
{
var value = VariableHandler.Add(left, VariableValue.Create(-1));
if (value.IsEmpty)
{
throw TypeMismatch(left.Type, VariableType.Int);
}
Assign(variables, value);
return(left);
}
}
