//Pipe/Alternative
internal static BnfExpression Op_Pipe(BnfTerm term1, BnfTerm term2)
{
//Check term1 and see if we can use it as result, simply adding term2 as operand
BnfExpression expr1 = term1 as BnfExpression;
if (expr1 == null) //either not expression at all, or Pipe-type expression (count > 1)
{
expr1 = new BnfExpression(term1);
}
//Check term2; if it is an expression and is simple sequence (Data.Count == 1) then add this sequence directly to expr1
BnfExpression expr2 = term2 as BnfExpression;
//1. term2 is a simple expression
if (expr2 != null && expr2.Data.Count == 1) // if it is simple sequence (plus operation), add it directly
{
expr1.Data.Add(expr2.Data[0]);
return(expr1);
}
//2. term2 is not a simple expression
expr1.Data.Add(new BnfTermList()); //add a list for a new OR element (new "plus" sequence)
expr1.Data[expr1.Data.Count - 1].Add(term2); // and put term2 there if it is not Empty pseudo-element
return(expr1);
}
public NonTerminal(string name, BnfExpression expression)
: this(name) {
Rule = expression;
}
