public override PrimitiveType FindPrimitiveType()
{
PrimitiveType leftType;
PrimitiveType rightType;
switch (OperatorToken)
{
case JSToken.Assign:
case JSToken.Comma:
// returns whatever type the right operand is
return(Operand2.FindPrimitiveType());
case JSToken.BitwiseAnd:
case JSToken.BitwiseAndAssign:
case JSToken.BitwiseOr:
case JSToken.BitwiseOrAssign:
case JSToken.BitwiseXor:
case JSToken.BitwiseXorAssign:
case JSToken.Divide:
case JSToken.DivideAssign:
case JSToken.LeftShift:
case JSToken.LeftShiftAssign:
case JSToken.Minus:
case JSToken.MinusAssign:
case JSToken.Modulo:
case JSToken.ModuloAssign:
case JSToken.Multiply:
case JSToken.MultiplyAssign:
case JSToken.RightShift:
case JSToken.RightShiftAssign:
case JSToken.UnsignedRightShift:
case JSToken.UnsignedRightShiftAssign:
// always returns a number
return(PrimitiveType.Number);
case JSToken.Equal:
case JSToken.GreaterThan:
case JSToken.GreaterThanEqual:
case JSToken.In:
case JSToken.InstanceOf:
case JSToken.LessThan:
case JSToken.LessThanEqual:
case JSToken.NotEqual:
case JSToken.StrictEqual:
case JSToken.StrictNotEqual:
// always returns a boolean
return(PrimitiveType.Boolean);
case JSToken.PlusAssign:
case JSToken.Plus:
// if either operand is known to be a string, then the result type is a string.
// otherwise the result is numeric if both types are known.
leftType = Operand1.FindPrimitiveType();
rightType = Operand2.FindPrimitiveType();
return((leftType == PrimitiveType.String || rightType == PrimitiveType.String)
? PrimitiveType.String
: (leftType != PrimitiveType.Other && rightType != PrimitiveType.Other
? PrimitiveType.Number
: PrimitiveType.Other));
case JSToken.LogicalAnd:
case JSToken.LogicalOr:
// these two are special. They return either the left or the right operand
// (depending on their values), so unless they are both known types AND the same,
// then we can't know for sure.
leftType = Operand1.FindPrimitiveType();
if (leftType != PrimitiveType.Other)
{
if (leftType == Operand2.FindPrimitiveType())
{
// they are both the same and neither is unknown
return(leftType);
}
}
// if we get here, then we don't know the type
return(PrimitiveType.Other);
default:
// shouldn't get here....
return(PrimitiveType.Other);
}
}