public virtual SyntaxNode Visit(AbstractVisitor visitor)
{
return(visitor.Visit(this));
}
public SyntaxNode Parse(Queue <LexicalElement> input, HashSet <Item> startPoint, Type acceptNode, List <ParserConfiguration> history = null, List <SyntaxException> exceptions = null, AbstractVisitor visitor = null)
{
Stack <SyntaxNode> nodeStack = new Stack <SyntaxNode>();
Stack <AnalyzerState> stateStack = new Stack <AnalyzerState>();
stateStack.Push(Slr1Table.States[startPoint]);
if (visitor == null)
{
visitor = PassthroughVisitor.Instance;
}
while (true)
{
try {
if (input.Count == 0)
{
if (nodeStack.Count > 0 && nodeStack.Peek().GetType() == acceptNode)
{
history?.Add(new ParserConfiguration(nodeStack, stateStack, input, null));
break;
}
var reducibleRules = new List <ProductionRule>(from item in stateStack.Peek().ItemSet
where item.Cursor == item.ProductionRule.Length
select item.ProductionRule);
if (reducibleRules.Count != 1)
{
var l = FindRightMostTerminal(nodeStack.Peek());
throw new SyntaxException($"Multiple or No Reducible Rule, last token \"{l.StringValue}\" at {l.LineNumber}:[{l.StartIndex}, {l.EndIndex}). Expected {String.Join(", ", from pred in stateStack.Peek().Action.Keys select pred.Name)}");
}
var reducibleRule = reducibleRules[0];
history?.Add(new ParserConfiguration(nodeStack, stateStack, input, new ReduceOperation()
{
ReduceBy = reducibleRule
}));
var argNodes = new SyntaxNode[reducibleRule.Length];
for (int i = argNodes.Length - 1; i >= 0; --i)
{
stateStack.Pop();
argNodes[i] = nodeStack.Pop();
}
nodeStack.Push(visitor.Visit(reducibleRule.Produce(argNodes)));
stateStack.Push(stateStack.Peek().GotoTable[reducibleRule.Key]);
}
else
{
var cur = input.Peek();
bool matched = false;
foreach (var action in stateStack.Peek().Action)
{
if (action.Key.Predicate(cur))
{
matched = true;
var operation = action.Value;
switch (operation)
{
case ShiftOperation so:
history?.Add(new ParserConfiguration(nodeStack, stateStack, input, so));
input.Dequeue();
nodeStack.Push(new TerminalNode(cur));
stateStack.Push(so.NextState);
break;
case ReduceOperation ro:
var reducibleRule = ro.ReduceBy;
history?.Add(new ParserConfiguration(nodeStack, stateStack, input, ro));
var argNodes = new SyntaxNode[reducibleRule.Length];
for (int i = argNodes.Length - 1; i >= 0; --i)
{
stateStack.Pop();
argNodes[i] = nodeStack.Pop();
}
nodeStack.Push(visitor.Visit(reducibleRule.Produce(argNodes)));
stateStack.Push(stateStack.Peek().GotoTable[reducibleRule.Key]);
break;
default:
throw new SyntaxException("Internal Error: Unknown Operation");
}
}
}
if (!matched)
{
throw new SyntaxException($"Unknown Token \"{cur.StringValue}\" at {cur.LineNumber}:[{cur.StartIndex}, {cur.EndIndex}), no matching operation. Expected {String.Join(", ", from pred in stateStack.Peek().Action.Keys select pred.Name)}");
}
}
} catch (SyntaxException e) {
exceptions?.Add(e);
var ero = new ErrorRecoveryOperation();
history?.Add(new ParserConfiguration(nodeStack, stateStack, input, ero));
if (input.Count == 0)
{
var ex = new SyntaxException("Error Recovery Failed: Unable to Reduce");
ero.Success = false;
exceptions.Add(ex);
throw ex;
}
List <object> intersection = new List <object>();
intersection.AddRange(Slr1Table.AllowedErrorRecoveryKey.Keys.Intersect(stateStack.Peek().GotoTable.Keys));
while (intersection.Count == 0 && stateStack.Count > 0)
{
stateStack.Pop();
nodeStack.Pop();
intersection.AddRange(Slr1Table.AllowedErrorRecoveryKey.Keys.Intersect(stateStack.Peek().GotoTable.Keys));
}
if (intersection.Count == 0)
{
var ex = new SyntaxException("Error Recovery Failed: No Recoverable State");
ero.Success = false;
exceptions.Add(ex);
throw ex;
}
var nextKey = intersection.First();
bool matched = false;
while (!matched && input.Count > 0)
{
foreach (var follow in Slr1Table.FollowSets[nextKey])
{
if (follow is TerminalPredicate tp && tp.Predicate(input.Peek()))
{
matched = true;
break;
}
input.Dequeue();
}
}
if (!matched)
{
var ex = new SyntaxException("Error Recovery Failed: No Followable Input");
ero.Success = false;
exceptions.Add(ex);
throw ex;
}
var nextState = stateStack.Peek().GotoTable[nextKey];
var nextNode = Slr1Table.AllowedErrorRecoveryKey[nextKey]();
stateStack.Push(nextState);
nodeStack.Push(visitor.Visit(nextNode));
ero.Success = true;
}
}
return(nodeStack.Pop());
}
