public void GenerateAutomaton()
{
SubProduction startingRule = Grammar.Instance.First(x => x.Identifier == ParserConstants.Initial).First();
GrammarSymbols = Grammar.Instance.Symbols();
Item startingItem = new Item(startingRule, 0, new HashSet <TerminalExpressionDefinition> {
new TerminalExpressionDefinition {
TokenType = TokenType.EndMarker
}
});
Initial = new ItemSet(new List <Item> {
startingItem
}).Closure();
CanonicalSets = Initial.GetCanonicalSets(GrammarSymbols);
PropogateLookaheads(GrammarSymbols);
}
private bool Reduce(ActionParsingTableEntry entry)
{
SubProduction subProduction = null;
if (entry.Items.Count > 1)
{
Item match = entry.Items.First(x => x.Lookahead.Any(x => x.TokenType == Current.Type));
subProduction = match.SubProduction;
}
else
{
subProduction = entry.Items.First().SubProduction;
}
NonTerminalExpressionDefinition target = new NonTerminalExpressionDefinition {
Identifier = subProduction.Production.Identifier
};
ParsingNode parsingNode = new ParsingNode()
{
Expression = new NonTerminalExpression
{
Identifier = subProduction.Production.Identifier,
},
Parser = this,
SubProduction = subProduction
};
for (int y = subProduction.Count - 1; y >= 0; y--)
{
for (int i = ParsingNodes.Count - 1; i >= 0; i--)
{
if (ParsingNodes[i].Parent != null)
{
continue;
}
if (ParsingNodes[i].Expression is NonTerminalExpression ne &&
subProduction[y] is NonTerminalExpressionDefinition ned)
{
if (ne.Identifier == ned.Identifier)
{
ParsingNodes[i].Expression.Key = ned.Key;
ParsingNodes[i].Parent = parsingNode;
break;
}
}
if (ParsingNodes[i].Expression is TerminalExpression te &&
subProduction[y] is TerminalExpressionDefinition ted)
{
if (te.TokenType == ted.TokenType)
{
ParsingNodes[i].Parent = parsingNode;
break;
}
}
}
}
ParsingNodes.Add(parsingNode);
List <ExpressionDefinition> expressionDefinitionsToRemove = subProduction.Where(x => !(x is SemanticActionDefinition) && !(x is TerminalExpressionDefinition ted && ted.TokenType == TokenType.EmptyString)).ToList();
for (int i = 0; i < expressionDefinitionsToRemove.Count(); i++)
{
Stack.RemoveAt(Stack.Count - 1);
}
ItemSet tos = Stack.Last();
List <ParsingTableEntry> entries = ParsingTable.GetSegment(tos).Entries
.Where(x => x is GotoParsingTableEntry g &&
g.ItemSet == tos &&
g.ExpressionDefinition.IsEqualTo(target)).ToList();
if (entries.Count > 1)
{
throw new Exception();
}
GotoParsingTableEntry gotoEntry = (GotoParsingTableEntry)entries.First();
if (DebugModeEnabled)
{
Console.WriteLine("REDUCE DEST " + gotoEntry.Destination.Id + ", TARGET " + target.ToString());
}
Stack.Add(gotoEntry.Destination);
return(true);
}