private void PrepareToParse()
{
Token token = new Token();
token.State = m_initLalrState;
token.SetParent(m_symbols[m_startSymbol]);
m_tempStack.PushToken(token);
}
/// This function analyzes a token and either:
/// 1. Makes a SINGLE reduction and pushes a complete Reduction object on the stack
/// 2. Accepts the token and shifts
/// 3. Errors and places the expected symbol indexes in the Tokens list
/// The Token is assumed to be valid and WILL be checked
private ParseResult ParseToken(Token p_token)
{
ParseResult result = ParseResult.InternalError;
LRActionTable table = m_LalrTables[m_LalrState];
LRAction action = table.GetActionForSymbol(p_token.TableIndex);
if (action != null)
{
m_haveReduction = false;
m_outputTokens.Clear();
switch (action.Action)
{
case Action.Accept:
m_haveReduction = true;
result = ParseResult.Accept;
break;
case Action.Shift:
p_token.State = m_LalrState = action.Value;
m_tempStack.PushToken(p_token);
result = ParseResult.Shift;
break;
case Action.Reduce:
result = Reduce(m_rules[action.Value]);
break;
}
}
else
{
// syntax error - fill expected tokens.
m_outputTokens.Clear();
foreach (LRAction a in table.Members)
{
SymbolType kind = a.Symbol.Kind;
if (kind == SymbolType.Terminal || kind == SymbolType.End)
{
m_outputTokens.PushToken(new Token(a.Symbol));
}
}
result = ParseResult.SyntaxError;
}
return(result);
}
/* public methods */
/// Pushes the specified token onto the internal input queue.
/// It will be the next token analyzed by the parsing engine.
public void PushInputToken(Token p_token)
{
m_inputTokens.PushToken(p_token);
}