private static IEnumerable <Symbol> AllSymbols(Nonterminal start)
{
var already = new HashSet <Symbol>();
void all(Nonterminal current)
{
already.Add(current);
foreach (var chain in current.Body)
{
foreach (var symbol in chain)
{
if (!already.Contains(symbol))
{
if (symbol is Nonterminal rule)
{
all(rule);
}
else
{
already.Add(symbol);
}
}
}
}
}
all(start);
return(already);
}
public Grammar(Nonterminal start, List <Production> productions)
{
Start = start;
Productions = productions;
Nonterminals = new HashSet <Nonterminal>(AllUsedSymbols(productions).OfType <Nonterminal>().Concat(Enumerable.Repeat(start, 1))).ToList();
Terminals = new HashSet <Terminal>(AllUsedSymbols(productions).OfType <Terminal>()).ToList();
}
private void Dump(TextWriter writer, Nonterminal rule)
{
writer.WriteLine($"{rule} =");
var body = string.Join(" |\n ", rule.Body.Select(prod => prod.Count == 0 ? "ε" : string.Join(" ", prod)));
writer.WriteLine($" {body}");
}
public Production(Nonterminal nonterminal, SymbolList symbols, Bools drops, Bools promotes)
{
Id = -1;
Nonterminal = nonterminal;
Symbols = symbols;
Drops = drops;
Promotes = promotes;
//Debug.Assert(!IsPromote);
}
public Grammar(Nonterminal start)
{
Start = start;
Symbols = AllSymbols(start).ToList();
Nonterminals = new HashSet <Nonterminal>(Symbols.OfType <Nonterminal>()).ToList();
Terminals = new HashSet <Terminal>(Symbols.OfType <Terminal>()).ToList();
Productions = MakeProductions(Nonterminals).ToList();
Whitespace = new List <Terminal>();
MakeIsNullable();
}
public Production(Nonterminal head, List <Symbol> body)
{
Head = head;
Body = body;
}
public IEnumerable <Production> ProductionsFor(Nonterminal nonterminal)
{
return(Productions.Where(production => production.Head.Equals(nonterminal)));
}
public bool IsTransitiveNullable(Nonterminal nonTerminal)
{
return(false);
//throw new System.NotImplementedException();
}
