private void ValidateGrammar()
{
var createAst = _grammar.LanguageFlags.IsSet(LanguageFlags.CreateAst);
var invalidTransSet = new NonTerminalSet();
foreach (var nt in _grammarData.NonTerminals)
{
if (nt.Flags.IsSet(TermFlags.IsTransient))
{
//List non-terminals cannot be marked transient - otherwise there may be some ambiguities and inconsistencies
if (nt.Flags.IsSet(TermFlags.IsList))
{
_language.Errors.Add(GrammarErrorLevel.Error, null, Resources.ErrListCannotBeTransient, nt.Name);
}
//Count number of non-punctuation child nodes in each production
foreach (var prod in nt.Productions)
{
if (CountNonPunctuationTerms(prod) > 1)
{
invalidTransSet.Add(nt);
}
}
}
//Validate error productions
foreach (var prod in nt.Productions)
{
if (prod.Flags.IsSet(ProductionFlags.IsError))
{
var lastTerm = prod.RValues[prod.RValues.Count - 1];
if (!(lastTerm is Terminal) || lastTerm == _grammar.SyntaxError)
{
_language.Errors.Add(GrammarErrorLevel.Warning, null, Resources.ErrLastTermOfErrorProd, nt.Name);
}
// "The last term of error production must be a terminal. NonTerminal: {0}"
}
}
}
if (invalidTransSet.Count > 0)
{
_language.Errors.Add(GrammarErrorLevel.Error, null, Resources.ErrTransientNtMustHaveOneTerm, invalidTransSet.ToString());
}
}
private static void ComputeNonTerminalsNullability(GrammarData data)
{
var undecided = data.NonTerminals;
while (undecided.Count > 0)
{
var newUndecided = new NonTerminalSet();
foreach (var nt in undecided)
{
if (!ComputeNullability(nt))
{
newUndecided.Add(nt);
}
}
if (undecided.Count == newUndecided.Count)
{
return; //we didn't decide on any new, so we're done
}
undecided = newUndecided;
}
}
