private void CoerceTypes(string operatorName, ref Expression leftExpr, ref Expression rightExpr)
{
if (leftExpr.Type != rightExpr.Type)
{
var leftType = TypeFns.GetNonNullableType(leftExpr.Type);
var rightType = TypeFns.GetNonNullableType(rightExpr.Type);
if (leftType == typeof(String))
{
ConvertExpr(ref rightExpr, ref leftExpr);
}
else if (rightType == typeof(String))
{
ConvertExpr(ref leftExpr, ref rightExpr);
}
else if ((TypeFns.IsNumericType(leftType) || TypeFns.IsEnumType(leftType)) && (TypeFns.IsNumericType(rightType) || TypeFns.IsEnumType(rightType)))
{
var leftIx = NumericTypes.IndexOf(leftType);
var rightIx = NumericTypes.IndexOf(rightType);
if (leftIx < rightIx)
{
ConvertExpr(ref leftExpr, ref rightExpr);
}
else
{
ConvertExpr(ref rightExpr, ref leftExpr);
}
}
else if (leftType == typeof(Guid) ||
leftType == typeof(DateTime) ||
leftType == typeof(Boolean) ||
leftType == typeof(TimeSpan) ||
TypeFns.IsNumericType(leftType) ||
TypeFns.IsEnumType(leftType))
{
ConvertExpr(ref rightExpr, ref leftExpr);
}
else
{
throw new Exception("Unable to perform operation: " + operatorName + "on types:"
+ leftExpr.Type + ", " + rightExpr.Type);
}
}
}
// coerce fromExpr to toExpr type
// but also convert both to nonnullable types.
private void ConvertExpr(ref Expression fromExpr, ref Expression toExpr)
{
var constExpr = fromExpr as ConstantExpression;
var toType = TypeFns.GetNonNullableType(toExpr.Type);
if (constExpr != null)
{
if (constExpr.Value == null)
{
return;
}
var newValue = Convert.ChangeType(constExpr.Value, toType);
fromExpr = Expression.Constant(newValue);
}
else
{
fromExpr = Expression.Convert(fromExpr, toType);
}
if (TypeFns.IsNullableType(toExpr.Type))
{
toExpr = Expression.Convert(toExpr, toType);
}
}