private IForestNode CreateNullParseNode(NonTerminal symbol, int location)
{
var symbolNode = NodeSet.AddOrGetExistingSymbolNode(symbol, location, location);
var nullNode = new SymbolForestNode(symbol, location, location); //new EpsilonForestNode(location);
symbolNode.AddUniqueFamily(nullNode);
return(symbolNode);
}
private IForestNode CreateParseNode(
DottedRule nextDottedRule,
int origin,
IForestNode w,
IForestNode v,
int location)
{
Assert.IsNotNull(v, nameof(v));
var anyPreDotRuleNull = true;
if (nextDottedRule.Dot > 1)
{
var preDotPrecursorSymbol = nextDottedRule.Production[nextDottedRule.Dot - 2];
anyPreDotRuleNull = IsSymbolTransitiveNullable(preDotPrecursorSymbol);
}
var anyPostDotRuleNull = IsSymbolTransitiveNullable(nextDottedRule.PostDotSymbol);
if (anyPreDotRuleNull && !anyPostDotRuleNull)
{
return(v);
}
IInternalForestNode internalNode;
if (anyPostDotRuleNull)
{
internalNode = NodeSet.AddOrGetExistingSymbolNode(nextDottedRule.Production.LeftHandSide, origin, location);
}
else
{
internalNode = NodeSet.AddOrGetExistingIntermediateNode(nextDottedRule, origin, location);
}
// if w = null and y doesn't have a family of children (v)
if (w == null)
{
internalNode.AddUniqueFamily(v);
}
// if w != null and y doesn't have a family of children (w, v)
else
{
internalNode.AddUniqueFamily(v, w);
}
return(internalNode);
}