/// <summary>
/// Reduz a regra.
/// </summary>
/// <param name="rule"></param>
/// <returns></returns>
private ParseResult Reduce(Rule rule)
{
ParseResult reduceEliminated;
Token token;
if (this._trimReductions && rule.ContainsOneNonTerminal)
{
token = _tempStack.PopToken();
token.SetParent(rule.RuleNonTerminal);
reduceEliminated = ParseResult.ReduceEliminated;
}
else
{
Reduction reduction = new Reduction();
reduction.ParentRule = rule;
_tempStack.PopTokensInto(reduction, rule.SymbolCount);
token = new Token();
token.Data = reduction;
token.SetParent(rule.RuleNonTerminal);
this._haveReduction = true;
reduceEliminated = ParseResult.ReduceNormal;
}
int state = _tempStack.PeekToken().State;
LRAction actionForSymbol = _LalrTables[state].GetActionForSymbol(rule.RuleNonTerminal.TableIndex);
if (actionForSymbol == null)
{
throw new ParserException("Action for LALR state is null");
}
token.State = _LalrState = actionForSymbol.Value;
this._tempStack.PushToken(token);
return(reduceEliminated);
}
/// <summary>
/// Adiciona um novo item
/// </summary>
/// <param name="symbol"></param>
/// <param name="action"></param>
/// <param name="value"></param>
public void AddItem(Symbol symbol, Text.Parser.Action action, int value)
{
LRAction lrAction = new LRAction();
lrAction.Symbol = symbol;
lrAction.Action = action;
lrAction.Value = value;
_members.Add(lrAction);
}
/// <summary>
/// Executa parser para o token.
/// </summary>
/// <param name="token"></param>
/// <returns></returns>
private ParseResult ParseToken(Token token)
{
ParseResult result = ParseResult.InternalError;
LRActionTable table = _LalrTables[_LalrState];
LRAction action = table.GetActionForSymbol(token.TableIndex);
if (action != null)
{
_haveReduction = false;
_outputTokens.Clear();
switch (action.Action)
{
case Action.Accept:
_haveReduction = true;
result = ParseResult.Accept;
break;
case Action.Shift:
token.State = _LalrState = action.Value;
_tempStack.PushToken(token);
result = ParseResult.Shift;
break;
case Action.Reduce:
result = Reduce(_rules[action.Value]);
break;
}
}
else
{
_outputTokens.Clear();
foreach (LRAction a in table.Members)
{
SymbolType kind = a.Symbol.Kind;
if (kind == SymbolType.Terminal || kind == SymbolType.End)
{
_outputTokens.PushToken(new Token(a.Symbol));
}
}
result = ParseResult.SyntaxError;
}
return(result);
}