protected override MatchContext Match(Ust ust, MatchContext context)
{
var unaryOperatorLiteral = ust as UnaryOperatorLiteral;
if (unaryOperatorLiteral == null)
{
return(context.Fail());
}
return(UnaryOperator.Equals(unaryOperatorLiteral.UnaryOperator)
? context.AddMatch(unaryOperatorLiteral)
: context.Fail());
}
/// <summary>
/// Checks if this expression can generate an empty word.
/// </summary>
/// <returns></returns>
public bool GeneratesEmptyWord()
{
//if (role.Equals(PartialExpressionRole.EmptyWord))
// return true;
if (_operator.Equals(UnaryOperator.KleeneStar))
{
return(true);
}
switch (role)
{
case PartialExpressionRole.EmptyWord:
return(true);
case PartialExpressionRole.Union:
if (parts.Any(x => x.GeneratesEmptyWord()))
{
return(true);
}
break;
case PartialExpressionRole.Concatenation:
if (parts.All(x => x.GeneratesEmptyWord()))
{
return(true);
}
break;
}
//if (role.Equals(PartialExpressionRole.Union)
// && parts.Any(x => x.GeneratesEmptyWord()))
// return true;
//if (role.Equals(PartialExpressionRole.Concatenation)
// && parts.All(x => x.GeneratesEmptyWord()))
// return true;
return(false);
}
