public void Visit(UnaryExpression e)
{
var o = _results.Pop();
switch (e.Operator)
{
case UnaryOperator.Minus:
o *= (Number)(-1m);
break;
case UnaryOperator.Plus:
break;
}
_results.Push(o);
}
static Expression ParseUnaryExpression(Lexer lexer)
{
var rp = lexer.CreateRestorePoint();
var type = lexer.CurrentToken.Type;
switch (type)
{
case TokenType.Plus:
case TokenType.Dash:
if (!lexer.Next())
{
rp();
return null;
}
break;
}
var operand = ParsePrimaryExpression(lexer);
if (operand == null)
{
rp();
return null;
}
Expression result;
switch (type)
{
case TokenType.Plus:
result = new UnaryExpression(operand, UnaryOperator.Plus);
break;
case TokenType.Dash:
result = new UnaryExpression(operand, UnaryOperator.Minus);
break;
default:
result = operand;
break;
}
return result;
}
