private void Hold(SymbolToken val)
{
_heldInput.Add(val);
if (val.Type == SymbolType.OpenBracket)
{
_parentheses++;
}
if (val.Type == SymbolType.CloseBracket)
{
_parentheses--;
}
// Unary operations are the only case where an open parenthesis
// that applies to the negation may come as the second token.
// Unparsed negations also count, handled below as a special case
// (since they do not require parentheses)
if (_heldInput.Count == 1 && val.Type.IsUnaryOperation())
{
return;
}
// be careful here: new, unparsed subtractions can be continued
// negation tokens. Be sure to handle those!
if (_parentheses == 0 && val.Type != SymbolType.Subtraction)
{
var np = new NegationProcessor(_heldInput);
Output(np.PumpAll());
Output(SymbolToken.CloseBracket);
_heldInput = new List <SymbolToken>();
_holdInput = false;
}
}
public static List <SymbolToken> Parse(string expression, VariableContext context)
{
var pipe1 = new StringToPrimitiveTokenPipe(expression, context);
var pipe2 = new MatchAllParenthesesProcessor(pipe1);
var pipe3 = new NegationProcessor(pipe2);
var pipe4 = new RedundantParenthesesProcessor(pipe3);
var pipe5 = new TokenValidater(pipe4);
return(pipe5.PumpAll());
}
protected override void Finish()
{
if (_heldInput.Count == 0)
{
return;
}
var np = new NegationProcessor(_heldInput);
Output(np.PumpAll());
Output(SymbolToken.CloseBracket);
_parentheses = 0;
_heldInput = new List <SymbolToken>();
_lastOutput = SymbolToken.OpenBracket;
_holdInput = false;
}