Add runtime.Enum

[UrbanskiDawid]

this is an implementation of runtime.Enum required for C.1.4 Integer to enumerated int2enum

[UrbanskiDawid]

@WypustekMichal this is for int2enum please use it to implement your function

[UrbanskiDawid]

@5nord updated 4357ae7

support for ranges
support for negative values
old Enum is now EnumType
new Enum contains:

• reference to EnumType

>> type enumerated ET {red(-3), green, blue(+1)};
>> ET
<< ET{red(-3), green(-2), blue(1)}

• selected key

>> var ET e := red;
>> e
<< ET::red

controversial chantes:

1. Enum remembers reference to 'type enumerated' (EnumType)
2. adding 'type enumerated' (EnumType) in interpreter now add 'frozen' Enums to env for each enum key.

please re-check with new commit

[5nord]

It's great to see that with only moderate change you model something challenging as TTCN-3 enumeration semantics ☺️

Some details should be worked out. For example: Can we already implement a mechanism to assign the correct enum-type?

ntt -i
ntt dev (none, unknown)
>> type enumerated U { E }
>> type enumerated V { E }
>> var U e := E
>> e
V::E

Also, I like the syntax ::, but it's non-standard. I think in TTCN-3 we should write V.E instead (we need to check this though).

[UrbanskiDawid]

It's great to see that with only moderate change you model something challenging as TTCN-3 enumeration semantics ☺️

Some details should be worked out. For example: Can we already implement a mechanism to assign the correct enum-type?

ntt -i
ntt dev (none, unknown)
>> type enumerated U { E }
>> type enumerated V { E }
>> var U e := E
>> e
V::E

Also, I like the syntax ::, but it's non-standard. I think in TTCN-3 we should write V.E instead (we need to check this though).

done

[5nord]

The type is not right, do you maybe know why?

ntt -i
ntt dev (none, unknown)
>> type enumerated U { E }
>> type enumerated V { E }
>> var U e := E
>> e
V.E
``

[UrbanskiDawid]

type enumerated U { E }

yes
there are two issues:

1. 'U.E' is overridden by 'V.E' - I have update this, now this will fail to create enum with same elements
2. 'e' is assigned without any type checking, it's literally setting 'E' as 'e' in ENV .