public void Action(Expansion e) { if (e is OneOrMore) { if (Semanticize.EmptyExpansionExists(((OneOrMore)e).Expansion)) { CSharpCCErrors.SemanticError(e, "Expansion within \"(...)+\" can be matched by empty string."); } } else if (e is ZeroOrMore) { if (Semanticize.EmptyExpansionExists(((ZeroOrMore)e).Expansion)) { CSharpCCErrors.SemanticError(e, "Expansion within \"(...)*\" can be matched by empty string."); } } else if (e is ZeroOrOne) { if (Semanticize.EmptyExpansionExists(((ZeroOrOne)e).Expansion)) { CSharpCCErrors.SemanticError(e, "Expansion within \"(...)?\" can be matched by empty string."); } } }
public static void choiceCalc(Choice choice) { int first = firstChoice(choice); // dbl[i] and dbr[i] are lists of size limited matches for choice i // of choice. dbl ignores matches with semantic lookaheads (when force_la_check // is false), while dbr ignores semantic lookahead. IList <MatchInfo>[] dbl = new IList <MatchInfo> [choice.Choices.Count]; IList <MatchInfo>[] dbr = new IList <MatchInfo> [choice.Choices.Count]; int[] minLA = new int[choice.Choices.Count - 1]; MatchInfo[] overlapInfo = new MatchInfo[choice.Choices.Count - 1]; int[] other = new int[choice.Choices.Count - 1]; MatchInfo m; IList <MatchInfo> v; bool overlapDetected; for (int la = 1; la <= Options.getChoiceAmbiguityCheck(); la++) { MatchInfo.laLimit = la; LookaheadWalk.considerSemanticLA = !Options.getForceLaCheck(); for (int i = first; i < choice.Choices.Count - 1; i++) { LookaheadWalk.sizeLimitedMatches = new List <MatchInfo>(); m = new MatchInfo(); m.firstFreeLoc = 0; v = new List <MatchInfo>(); v.Add(m); LookaheadWalk.genFirstSet(v, (Expansion)choice.Choices[i]); dbl[i] = LookaheadWalk.sizeLimitedMatches; } LookaheadWalk.considerSemanticLA = false; for (int i = first + 1; i < choice.Choices.Count; i++) { LookaheadWalk.sizeLimitedMatches = new List <MatchInfo>(); m = new MatchInfo(); m.firstFreeLoc = 0; v = new List <MatchInfo>(); v.Add(m); LookaheadWalk.genFirstSet(v, (Expansion)choice.Choices[i]); dbr[i] = LookaheadWalk.sizeLimitedMatches; } if (la == 1) { for (int i = first; i < choice.Choices.Count - 1; i++) { Expansion exp = (Expansion)choice.Choices[i]; if (Semanticize.EmptyExpansionExists(exp)) { CSharpCCErrors.Warning(exp, "This choice can expand to the empty token sequence " + "and will therefore always be taken in favor of the choices appearing later."); break; } else if (CodeCheck(dbl[i])) { CSharpCCErrors.Warning(exp, "CSHARPCODE non-terminal will force this choice to be taken " + "in favor of the choices appearing later."); break; } } } overlapDetected = false; for (int i = first; i < choice.Choices.Count - 1; i++) { for (int j = i + 1; j < choice.Choices.Count; j++) { if ((m = overlap(dbl[i], dbr[j])) != null) { minLA[i] = la + 1; overlapInfo[i] = m; other[i] = j; overlapDetected = true; break; } } } if (!overlapDetected) { break; } } for (int i = first; i < choice.Choices.Count - 1; i++) { if (explicitLA((Expansion)choice.Choices[i]) && !Options.getForceLaCheck()) { continue; } if (minLA[i] > Options.getChoiceAmbiguityCheck()) { CSharpCCErrors.Warning("Choice conflict involving two expansions at"); Console.Error.Write(" line " + ((Expansion)choice.Choices[i]).Line); Console.Error.Write(", column " + ((Expansion)choice.Choices[i]).Column); Console.Error.Write(" and line " + ((Expansion)choice.Choices[other[i]]).Line); Console.Error.Write(", column " + ((Expansion)choice.Choices[other[i]]).Column); Console.Error.WriteLine(" respectively."); Console.Error.WriteLine(" A common prefix is: " + image(overlapInfo[i])); Console.Error.WriteLine(" Consider using a lookahead of " + minLA[i] + " or more for earlier expansion."); } else if (minLA[i] > 1) { CSharpCCErrors.Warning("Choice conflict involving two expansions at"); Console.Error.Write(" line " + ((Expansion)choice.Choices[i]).Line); Console.Error.Write(", column " + ((Expansion)choice.Choices[i]).Column); Console.Error.Write(" and line " + ((Expansion)choice.Choices[other[i]]).Line); Console.Error.Write(", column " + ((Expansion)choice.Choices[other[i]]).Column); Console.Error.WriteLine(" respectively."); Console.Error.WriteLine(" A common prefix is: " + image(overlapInfo[i])); Console.Error.WriteLine(" Consider using a lookahead of " + minLA[i] + " for earlier expansion."); } } }