//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);
}
private void CollectAllElementsRecursive(BnfTerm element)
{
//Terminal
Terminal term = element as Terminal;
// Do not add pseudo terminals defined as static singletons in Grammar class (Empty, Eof, etc)
// We will never see these terminals in the input stream.
// Filter them by type - their type is exactly "Terminal", not derived class.
if (term != null && !Data.Terminals.Contains(term) && term.GetType() != typeof(Terminal))
{
Data.Terminals.Add(term);
return;
}
//NonTerminal
NonTerminal nt = element as NonTerminal;
if (nt == null || Data.NonTerminals.Contains(nt))
{
return;
}
if (nt.Name == null)
{
if (nt.Rule != null && !string.IsNullOrEmpty(nt.Rule.Name))
{
nt.Name = nt.Rule.Name;
}
else
{
nt.Name = "NT" + (_unnamedCount++);
}
}
Data.NonTerminals.Add(nt);
if (nt.Rule == null)
{
AddError("Non-terminal {0} has uninitialized Rule property.", nt.Name);
Data.AnalysisCanceled = true;
return;
}
//check all child elements
foreach (BnfTermList elemList in nt.Rule.Data)
{
for (int i = 0; i < elemList.Count; i++)
{
BnfTerm child = elemList[i];
if (child == null)
{
AddError("Rule for NonTerminal {0} contains null as an operand in position {1} in one of productions.", nt, i);
continue; //for i loop
}
//Check for nested expression - convert to non-terminal
BnfExpression expr = child as BnfExpression;
if (expr != null)
{
child = new NonTerminal(null, expr);
elemList[i] = child;
}
CollectAllElementsRecursive(child);
}
}
}//method
protected static BnfTerm WithQ(BnfExpression expression)
{
return(ToElement(expression).Q());
}
public NonTerminal(string name, BnfExpression expression) : this(name) {
_rule = expression;
}
protected static BnfTerm ToElement(BnfExpression expression)
{
string name = expression.ToString();
return(new NonTerminal(name, expression));
}
