private Expr ParseFactor()
{
if (this.index == this.tokens.Count)
{
throw new System.Exception("expected expression, got EOF");
}
if (this.tokens[this.index] is StringToken)
{
StringVal stringLiteral = new StringVal();
stringLiteral.Value = ((StringToken)this.tokens[this.index]).Value;
MoveNext();
return(stringLiteral);
}
else if (this.tokens[this.index] is IntToken)
{
IntVal intVal = new IntVal();
intVal.Value = ((IntToken)this.tokens[this.index]).Value;
MoveNext();
return(intVal);
}
else if (this.tokens[this.index] is FloatToken)
{
FloatVal floVal = new FloatVal();
floVal.Value = ((FloatToken)this.tokens[this.index]).Value;
MoveNext();
return(floVal);
}
else if (this.tokens[this.index] is DoubleToken)
{
DoubleVal douVal = new DoubleVal();
douVal.Value = ((DoubleToken)this.tokens[this.index]).Value;
MoveNext();
return(douVal);
}
else if (this.tokens[this.index] is DecimalToken)
{
DecimalVal decVal = new DecimalVal();
decVal.Value = ((DecimalToken)this.tokens[this.index]).Value;
MoveNext();
return(decVal);
}
else if (this.tokens[this.index] is DateTimeToken)
{
DateTimeVal datVal = new DateTimeVal();
datVal.Value = ((DateTimeToken)this.tokens[this.index]).Value;
MoveNext();
return(datVal);
}
else if (this.tokens[this.index] is BoolToken)
{
BoolVal bolVal = new BoolVal();
bolVal.Value = ((BoolToken)this.tokens[this.index]).Value;
MoveNext();
return(bolVal);
}
else if (this.tokens[this.index] == Tokens.Null)
{
NullVal nullVal = new NullVal();
MoveNext();
return(nullVal);
}
else if (this.tokens[this.index] is IdentifierToken)
{
string ident = ((IdentifierToken)tokens[index]).Name;
MoveNext();
// function expr
if (MaybeEat(Tokens.LeftBracket))
{
FunctionExpr fun = new FunctionExpr();
fun = ParseFunction(ident);
return(fun);
}
// variable
else
{
Variable var = new Variable();
var.Ident = ident;
return(var);
}
}
else if (this.tokens[this.index] == Tokens.New)
{
MoveNext(); // eat new
return(ParseNewObject());
}
else if (this.tokens[this.index] == Tokens.LeftBracket)
{
// Eat LeftParenthesis
MoveNext();
Expr result = ParseExpr();
Eat(Tokens.RightBracket);
return(result);
}
else if (IsUnaryOperator(this.tokens[index]))
{
// Unary Expression
UnaryExpr result = new UnaryExpr();
if (MaybeEat(Tokens.Sub))
{
result.Op = TokenToBinOp(Tokens.Sub);
}
else if (MaybeEat(Tokens.Add))
{
result.Op = TokenToBinOp(Tokens.Add);
}
else if (MaybeEat(Tokens.Not))
{
result.Op = TokenToBinOp(Tokens.Not);
}
else
{
throw new System.Exception(string.Format(
"Operator '{0}' is not supported in unary expressions",
tokens[index]));
}
result.Expression = ParseFactor();
return(result);
}
else
{
throw new System.Exception("expected string literal, numeric literal, or variable");
}
}
private object CodeExecuteUnaryExpr(UnaryExpr ue)
{
object res = null;
bool notSupport = false;
object ex = GenExpr(ue.Expression);
switch (ue.Op)
{
case BinOp.Add:
if (ex == null)
{
notSupport = true;
}
else if (ex.GetType() == typeof(int))
{
res = Convert.ToInt32(ex);
}
else if (ex.GetType() == typeof(float))
{
res = Convert.ToSingle(ex);
}
else if (ex.GetType() == typeof(double))
{
res = Convert.ToDouble(ex);
}
else if (ex.GetType() == typeof(decimal))
{
res = Convert.ToDecimal(ex);
}
else
{
notSupport = true;
}
break;
case BinOp.Sub:
if (ex == null)
{
notSupport = true;
}
else if (ex.GetType() == typeof(int))
{
res = -1 * Convert.ToInt32(ex);
}
else if (ex.GetType() == typeof(float))
{
res = -1 * Convert.ToSingle(ex);
}
else if (ex.GetType() == typeof(double))
{
res = -1 * Convert.ToDouble(ex);
}
else if (ex.GetType() == typeof(decimal))
{
res = -1 * Convert.ToDecimal(ex);
}
else
{
notSupport = true;
}
break;
case BinOp.Not:
if (ex == null)
{
//notSupport = true;
res = 1;
}
else if (ex.GetType() == typeof(bool))
{
res = (ex.Equals(false)) ? 1 : 0;
}
else
{
res = (ex.Equals(0)) ? 1 : 0;
}
break;
default:
notSupport = true;
break;
}
if (notSupport)
{
throw new ApplicationException(string.Format(
"The operator '{0}' is not supported in this expression ", ue.Op));
}
else
{
return(res);
}
}