// the sections mentioned in comments of this method are from C# specification v1.2
public static Conversion GetImplicit(Operand op, Type to, bool onlyStandard, ITypeMapper typeMapper)
{
Type from = Operand.GetType(op, typeMapper);
Type toUnderlying = Helpers.GetNullableUnderlyingType(to);
if (to.Equals(from))
{
return(new Direct(typeMapper));
}
Type fromUnderlying = Helpers.GetNullableUnderlyingType(@from);
if (toUnderlying != null)
{
if (fromUnderlying != null)
{
Conversion c = GetImplicit(new FakeTypedOperand(fromUnderlying), toUnderlying, onlyStandard, typeMapper);
if (c.IsValid)
{
return(new ConvertNullable(typeMapper, c));
}
}
else
{
Conversion c = GetImplicit(op, toUnderlying, onlyStandard, typeMapper);
if (c.IsValid)
{
return(new WrapNullable(typeMapper, c));
}
}
}
// required for arrays created from TypeBuilder-s
if (from != null && to.IsArray && from.IsArray)
{
if (to.GetArrayRank() == from.GetArrayRank())
{
if (to.GetElementType().Equals(from.GetElementType()))
{
return(new Direct(typeMapper));
}
}
}
TypeCode tcFrom = Type.GetTypeCode(from);
TypeCode tcTo = Type.GetTypeCode(to);
byte ct = _convTable[(int)tcFrom][(int)tcTo];
// section 6.1.2 - Implicit numeric conversions
if (from != null && (from.IsPrimitive || Helpers.AreTypesEqual(from, typeof(decimal), typeMapper)) && (to.IsPrimitive || Helpers.AreTypesEqual(to, typeof(decimal), typeMapper)))
{
if (ct <= I)
{
if (Helpers.AreTypesEqual(from, typeof(decimal), typeMapper) || Helpers.AreTypesEqual(to, typeof(decimal), typeMapper))
{
// decimal is handled as user-defined conversion, but as it is a standard one, always enable UDC processing
onlyStandard = false;
}
else
{
return(new Primitive(typeMapper));
}
}
}
IntLiteral intLit = op as IntLiteral;
// section 6.1.3 - Implicit enumeration conversions
if (!onlyStandard && to.IsEnum && (object)intLit != null && intLit.Value == 0)
{
return(new Primitive(typeMapper));
}
// section 6.1.4 - Implicit reference conversions
if ((from == null || !from.IsValueType) && !to.IsValueType)
{
if (from == null) // from the null type to any reference type
{
return(new Direct(typeMapper));
}
if (to.IsAssignableFrom(from)) // the rest
{
return(new Direct(typeMapper));
}
}
if (from == null) // no other conversion from null type is possible
{
return(new Invalid(typeMapper));
}
// section 6.1.5 - Boxing conversions
if (from.IsValueType)
{
if (to.IsAssignableFrom(from))
{
return(new Boxing(typeMapper));
}
}
// section 6.1.6 - Implicit constant expression conversions
if ((object)intLit != null && Helpers.AreTypesEqual(from, typeof(int), typeMapper) && to.IsPrimitive)
{
int val = intLit.Value;
switch (tcTo)
{
case TypeCode.SByte:
if (val >= sbyte.MinValue && val <= sbyte.MaxValue)
{
return(new Direct(typeMapper));
}
break;
case TypeCode.Byte:
if (val >= byte.MinValue && val <= byte.MaxValue)
{
return(new Direct(typeMapper));
}
break;
case TypeCode.Int16:
if (val >= short.MinValue && val <= short.MaxValue)
{
return(new Direct(typeMapper));
}
break;
case TypeCode.UInt16:
if (val >= ushort.MinValue && val <= ushort.MaxValue)
{
return(new Direct(typeMapper));
}
break;
case TypeCode.UInt32:
if (val >= 0)
{
return(new Direct(typeMapper));
}
break;
case TypeCode.UInt64:
if (val >= 0)
{
return(new Direct(typeMapper));
}
break;
}
}
// section 6.1.7 - User-defined implicit conversions (details in section 6.4.3)
if (onlyStandard || Helpers.AreTypesEqual(from, typeof(object), typeMapper) || Helpers.AreTypesEqual(to, typeof(object), typeMapper) || from.IsInterface || to.IsInterface ||
to.IsSubclassOf(from) || from.IsSubclassOf(to))
{
return(new Invalid(typeMapper)); // skip not-permitted conversion attempts (section 6.4.1)
}
List <UserDefined> candidates = null;
FindCandidates(ref candidates, FindImplicitMethods(from, to, typeMapper), op, to, GetImplicit, typeMapper);
if (candidates == null)
{
return(new Invalid(typeMapper));
}
if (candidates.Count == 1)
{
return(candidates[0]);
}
return(UserDefined.FindImplicit(candidates, @from, to, typeMapper));
}
// the sections mentioned in comments of this method are from C# specification v1.2
public static Conversion GetImplicit(Operand op, Type to, bool onlyStandard)
{
try {
Type from = Operand.GetType(op);
if (to.Equals(from) || to.FullName == from.FullName || to.IsGenericParameter)
{
return(Direct.Instance);
}
// required for arrays created from TypeBuilder-s
if (from != null && to.IsArray && from.IsArray)
{
if (to.GetArrayRank() == from.GetArrayRank())
{
if (to.GetElementType().Equals(from.GetElementType()))
{
return(Direct.Instance);
}
}
}
TypeCode tcFrom = Type.GetTypeCode(from);
TypeCode tcTo = Type.GetTypeCode(to);
byte ct = convTable[(int)tcFrom][(int)tcTo];
// section 6.1.2 - Implicit numeric conversions
if ((from != null && (from.IsPrimitive || from == typeof(decimal))) && (to.IsPrimitive || to == typeof(decimal)))
{
if (ct <= I)
{
if (from == typeof(decimal) || to == typeof(decimal))
{
// decimal is handled as user-defined conversion, but as it is a standard one, always enable UDC processing
onlyStandard = false;
}
else
{
return(Primitive.Instance);
}
}
}
IntLiteral intLit = op as IntLiteral;
// section 6.1.3 - Implicit enumeration conversions
if (!onlyStandard && !to.IsGenericType && to.IsEnum && (object)intLit != null && intLit.Value == 0)
{
return(Primitive.Instance);
}
// section 6.1.4 - Implicit reference conversions
if ((from == null || !from.IsValueType) && !to.IsValueType)
{
if (from == null) // from the null type to any reference type
{
return(Direct.Instance);
}
if (to.IsAssignableFrom(from) || to.IsDerivedFrom(from)) // the rest
{
return(Direct.Instance);
}
if (from.Name.StartsWith("_Frame"))
{
return(Direct.Instance);
}
if (to == typeof(Operand))
{
return(UserDefined.Cast.Instance);
}
}
if (from == null) // no other conversion from null type is possible
{
return(Invalid.Instance);
}
// section 6.1.5 - Boxing conversions
if (from.IsValueType)
{
if (to.IsAssignableFrom(from))
{
return(Boxing.Instance);
}
}
// section 6.1.6 - Implicit constant expression conversions
if ((object)intLit != null && from == typeof(int) && to.IsPrimitive)
{
int val = intLit.Value;
switch (tcTo)
{
case TypeCode.SByte:
if (val >= sbyte.MinValue && val <= sbyte.MaxValue)
{
return(Direct.Instance);
}
break;
case TypeCode.Byte:
if (val >= byte.MinValue && val <= byte.MaxValue)
{
return(Direct.Instance);
}
break;
case TypeCode.Int16:
if (val >= short.MinValue && val <= short.MaxValue)
{
return(Direct.Instance);
}
break;
case TypeCode.UInt16:
if (val >= ushort.MinValue && val <= ushort.MaxValue)
{
return(Direct.Instance);
}
break;
case TypeCode.UInt32:
if (val >= 0)
{
return(Direct.Instance);
}
break;
case TypeCode.UInt64:
if (val >= 0)
{
return(Primitive.Instance);
}
break;
}
}
if (from == typeof(long))
{
LongLiteral longLit = op as LongLiteral;
if ((object)longLit != null && longLit.Value > 0)
{
return(Direct.Instance);
}
}
// section 6.1.7 - User-defined implicit conversions (details in section 6.4.3)
if (onlyStandard || from == typeof(object) || to == typeof(object) || from.IsInterface || to.IsInterface ||
to.IsSubclassOf(from) || from.IsSubclassOf(to))
{
return(Invalid.Instance); // skip not-permitted conversion attempts (section 6.4.1)
}
List <UserDefined> candidates = null;
FindCandidates(ref candidates, FindImplicitMethods(from, to), op, to, GetImplicit);
if (candidates == null)
{
return(Invalid.Instance);
}
if (candidates.Count == 1)
{
return(candidates[0]);
}
return(UserDefined.FindImplicit(candidates, from, to));
} catch (NotSupportedException e) {
return(Direct.Instance); // fallback to success :)
}
}