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 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); }
public static int Compare(TerminalSymbol sym, TerminalSymbol inputSymbol) { return(string.Compare(sym.c, inputSymbol.c)); }