System Verilog typedef of typedef - enums

Question

typedef enums allow a convenient way to describe a set of name-value pairs. Is there a way to chain them to create deeper structures using enum at all levels?
For instance, I have the following:
typedef enum logic {ALPHA=0, BETA=1} a_t;
typedef enum logic {GAMMA=0, DELTA=1} b_t;
typedef enum logic {ZETA=0, ETA=1} c_t;
...
I want to create a variable c which is formed of a_t and b_t. Is this possible?
Something like:
a_t b_t c;
so at every dimension of c, I can have enums.
EDIT: Some clarification - assume a_t, b_t and c_t are immutable as they are generated automatically. And there are hundreds of such different enums. I want to create bigger structures as I need because automatically generating all combinations of them would make the code too big and messy.
For instance, say my a_t describes number of masters and b_t describes number of slaves. I want to create a structure where I have this hierarchy in my signal, and at the same time allow enums for them to allow easy of readability and use.
So, something like this:
c[MASTER_0][SLAVE_0]
c[MASTER_0][SLAVE_1]
c[MASTER_1][SLAVE_0]
c[MASTER_1][SLAVE_1]

Answer 1

Are you perhaps referring to an associative array, such as:
c[ALPHA] = BETA;
If so, you could simply refer to it as:
b_t c[a_t];
Which means create an associative array c who's key is of enums a_t and value is of enums b_t. You could keep going if you'd like :)
typedef enum logic {ALPHA=0, BETA=1} a_t;
typedef enum logic {GAMMA=0, DELTA=1} b_t;
typedef enum logic {BAD_AT=0, GREEK_LETTERS=1} c_t;
c_t my_data_structure[a_t][b_t];
// Assigning a value
my_data_structure[ALPHA][GAMMA] = GREEK_LETTERS;
See an example on EDA Playground here.
Also, I think you're slightly misunderstanding the use of typedef. It does not exactly describe a set of name-value pairs, rather it gives a new name to a data type. It is the enum that is actually creating a 'set of name-value pairs', but I'd clarify that it is essentially assigning identifiers to values. It would help if you could explain the application for a clearer answer.

Answer 2

You cannot create one enum typedef from another or from a group of others. Some may call that extending an enum. You also cannot have a enum with multiple names for the same value.
What you can do is have an associative array with name/value pairs, and join those arrays together.
int a[string], b[string], c[string];
initial begin
a = '{"ALPHA":0, "BETA":1};
b = '{"GAMMA":0, "DELTA":1};
c = a;
foreach(b[s]) c[s]=b[s];
end
There are ways of gathering the names of each enumerated type to initialize the associative array as well.