public bool RecusiveDescent(BnfNonterminal t)
{
int rulesCount = t.RulesCount;
bool [] success = new bool [rulesCount];
int i = 0;
foreach (var rule in t.Rules)
{
var currentPosition = r.Position;
success [i] = true;
foreach (var sym in rule.Parts)
{
if (sym is NonterminalSymbol)
{
if (RecusiveDescent(sym as BnfNonterminal) == false)
{
success [i] = false;
break;
}
}
else
{
var inputSymbol = r.GetSymbol();
if (TerminalSymbol.Compare(sym as TerminalSymbol, inputSymbol) == 0)
{
continue;
}
else
{
success [i] = false;
break;
}
}
}
if (success [i] == false)
{
r.Position = currentPosition;
}
i++;
}
int total = 0;
foreach (var b in success)
{
if (b)
{
total++;
}
}
if (total > 1)
{
throw new ApplicationException();
}
return(total == 1);
}
public BnfNonterminal AddNonterminal(string name)
{
if (NonTerminals.ContainsKey(name))
{
return(NonTerminals [name]);
}
var nt = new BnfNonterminal(name);
NonTerminals.Add(name, nt);
return(nt);
}
BnfNonterminal Convert(EbnfNonterminal E)
{
BnfNonterminal B = null;
if (nonterminalConversions.ContainsKey(E))
{
var footprint = nonterminalConversions [E];
B = footprint.After;
}
else
{
B = Bnf.AddNonterminal(E.Name);
var footprint = new NonterminalConversionFootprint(E, B);
nonterminalConversions.Add(E, footprint);
}
return(B);
}
public static BnfGrammar Test1()
{
BnfNonterminal S = new BnfNonterminal(nameof(S));
BnfNonterminal A = new BnfNonterminal(nameof(A));
TerminalSymbol a = new TerminalSymbol(nameof(a));
TerminalSymbol b = new TerminalSymbol(nameof(b));
TerminalSymbol c = new TerminalSymbol(nameof(c));
TerminalSymbol d = new TerminalSymbol(nameof(d));
var rule1 = new BnfRule(S, new ISymbol [] { c, A, d });
var rule2 = new BnfRule(A, new ISymbol [] { a, b });
var rule3 = new BnfRule(A, new ISymbol [] { a });
var G = new BnfGrammar();
G.Add(rule1);
G.Add(rule2);
G.Add(rule3);
return(G);
}
BnfRule Convert(EbnfRule E)
{
BnfRule B = null;
if (ruleConversions.ContainsKey(E))
{
var footprint = ruleConversions [E];
B = footprint.After;
}
else
{
BnfNonterminal bn = Convert(E.Nonterminal);
List <ISymbol> terms = new List <ISymbol> ();
var p = E.RightPart;
if (p is EbnfEnumeration)
{
foreach (var pp in ((EbnfEnumeration)p).Parts)
{
if (pp is EbnfNonterminal)
{
var name = (pp as EbnfNonterminal).Name;
var node = Bnf.AddNonterminal(name);
terms.Add(node);
}
else
{
if (pp is EbnfTerminal)
{
var node = (TerminalSymbol)pp;
terms.Add(node);
}
else
{
throw new ApplicationException();
}
}
}
}
else
{
if (p is EbnfNonterminal)
{
var name = (p as EbnfNonterminal).Name;
var node = Bnf.AddNonterminal(name);
terms.Add(node);
}
else
{
if (p is EbnfTerminal)
{
var node = (TerminalSymbol)p;
terms.Add(node);
}
else
{
throw new ApplicationException();
}
}
}
B = new BnfRule(bn, terms.ToArray());
bn.Add(B);
var footprint = new RuleConversionFootprint(E, B);
ruleConversions.Add(E, footprint);
}
return(B);
}
public BnfRule(BnfNonterminal nt, ISymbol [] symbols_of_rule)
{
nonterminal = nt;
parts = symbols_of_rule;
}