private ParseTreeNode Parse(IEnumerator<Token> lexer, NonTerminal current, ParseTreeNode parent)
{
Production? prod = predictiveParseTable[current][lexer.Current.Terminal];
if (!prod.HasValue)
{
if (current.IsNullable)
{
var n = new ParseTreeNode(parent, current);
var c = new ParseTreeNode(n, new Token(new Terminal(""), "", lexer.Current.Line, lexer.Current.Column));
return n;
}
else
throw new ParseException("Unable to match " + lexer.Current + " at line " + lexer.Current.Line + " column " + lexer.Current.Column);
}
ParseTreeNode node = new ParseTreeNode(parent, current);
List<ParseTreeNode> nodes = new List<ParseTreeNode>();
for (int i = 0; i < prod.Value.Body.Length; i++)
{
var term = prod.Value.Body[i];
if (term is Terminal)
{
string match;
(term as Terminal).Match(lexer.Current.Value, 0, out match);
nodes.Add(new ParseTreeNode(node, lexer.Current));
if (!lexer.MoveNext())
for (int j = i + 1; j < prod.Value.Body.Length; j++)
if (!prod.Value.Body[j].IsNullable)
throw new ParseException("unexpected EOF");
}
else if (term is NonTerminal)
{
nodes.Add(Parse(lexer, term as NonTerminal, node));
}
else
throw new Exception("wtf?");
}
return node;
}
protected override ParseTreeNode Parse(Lexer lexer, NonTerminal root)
{
IEnumerator<Token> tokens = lexer.GetEnumerator();
var eof = !tokens.MoveNext();
if (eof)
{
if (root.Rules.Any(r => r.IsNullable()))
return new ParseTreeNode(null, new Token(new Terminal(""), "", 0, 0));
else
throw new ParseException("Empty string not matched by grammar");
}
Stack<ParseState> states = new Stack<ParseState>();
states.Push(MakeStateState(root, Grammar));
ParserAction action = ParserAction.Start;
Stack<ParseTreeNode> nodes = new Stack<ParseTreeNode>();
do
{
Production reduceProduction;
ParseState shiftState;
action = Action(states.Peek(), eof ? null : tokens.Current, out reduceProduction, out shiftState);
switch (action)
{
case ParserAction.Accept:
break;
case ParserAction.Error:
throw new ParseException(tokens.Current.ToString());
case ParserAction.Start:
default:
throw new NotImplementedException();
case ParserAction.Shift:
var newLeafNode = new ParseTreeNode(tokens.Current);
nodes.Push(newLeafNode);
states.Push(shiftState);
eof = !tokens.MoveNext();
break;
case ParserAction.Reduce:
var newNode = new ParseTreeNode(reduceProduction.Head);
var children = nodes.Take(reduceProduction.Body.Length).Reverse().Select((n, i) => new KeyValuePair<int, ParseTreeNode>(i, n));
foreach (var child in children)
{
child.Value.Parent = newNode;
nodes.Pop();
var bnfTerm = reduceProduction.Body[child.Key];
var terminal = bnfTerm as Terminal;
string match;
if (terminal != null)
{
if (!terminal.Match(child.Value.Token.Value, 0, out match))
throw new ParseException("Unexpected crap");
}
else if (!reduceProduction.Body[child.Key].Equals(child.Value.NonTerminal))
throw new ParseException("Unexpected crap");
}
nodes.Push(newNode);
for (int i = 0; i < reduceProduction.Body.Length; i++)
states.Pop();
states.Push(Goto(states.Peek(), reduceProduction.Head));
break;
}
} while (action != ParserAction.Accept);
if (nodes.Count != 1)
throw new ParseException("o_0");
return nodes.Pop();
}
public ParseTree(ParseTreeNode root)
{
this.root = root;
}
public ParseTreeNode(ParseTreeNode parent, Token token)
{
this.Parent = parent;
this.token = token;
}
public ParseTreeNode(ParseTreeNode parent, NonTerminal nonTerminal)
{
this.Parent = parent;
this.nonTerminal = nonTerminal;
}
public ParseTreeNode(ParseTreeNode parent, Token token)
{
this.Parent = parent;
this.token = token;
}
public ParseTreeNode(ParseTreeNode parent, NonTerminal nonTerminal)
{
this.Parent = parent;
this.nonTerminal = nonTerminal;
}
