C preprocessor macros: check if token is declared

Question

This is for experienced C preprocessors :

How can I declare enuma list of some identifiers and later during the switch-check check to see if the identifier is included in the list?

An example of what I need:

typedef enum { e1, e2, e3, e4, e5, e6 } e;

e x;
switch (x) {
#if DECLARED_IN_ENUM (e1)
  case e1 : ...
#endif
  /* etc. */
}

I thought about using the Boost sequence and expanding it to a comma-separated list, but how can I check later if the sequence contains a specific token?

EDIT . What I managed to do with Boost:

#define e1 e1
#define e2 e2
#define e3 e3
#define e4 e4
#define e5 e5
#define e6 e6
#define E (e1)(e2)(e3)(e4)(e5)(e6)

typedef enum { BOOST_PP_SEQ_ENUM(E) } e;

e x;
switch (x) {
#if defined (e1)
  case e1 : ...
#endif
  /* etc. */
}

This is not very pretty, and I would prefer something like:

#define E (e1)(e2)(e3)(e4)(e5)(e6)

typedef enum { BOOST_PP_SEQ_ENUM(E) } e;

e x;
switch (x) {
#if BOOST_PP_SEQ_CONTAINS (e1,E)
  case e1 : ...
#endif
  /* etc. */
}

but how to implement BOOST_PP_SEQ_CONTAINS?

Answer 1

, BOOST_PP_SEQ_CONTAINS . , .

, , , . -, BOOST_PP_SEQ_FOR_EACH:

#include <boost/preprocessor.hpp>

// General purpose macros:
#define EXPAND_ENUM_CASE_2(text1, text2) text1 ## text2
#define EXPAND_ENUM_CASE(r, data, elem) \
    case elem : EXPAND_ENUM_CASE_2(data ## _ ## CASE ## _ , elem)

, :

#define WORKDAY_ENUMERATORS (Monday)(Tuesday)(Wednesday)(Thursday)

enum Workday { BOOST_PP_SEQ_ENUM(WORKDAY_ENUMERATORS) }; 

, , . , , .

, , :

#define WORKDAY_CASE_Monday    { return "Mondays suck";                     }
#define WORKDAY_CASE_Tuesday   { return "Tuesdays are better than Mondays"; }
#define WORKDAY_CASE_Wednesday { return "Hooray for humpday!";              }
#define WORKDAY_CASE_Thursday  { return "Thursdays are okay";               }
#define WORKDAY_CASE_Friday    { return "No one really works on Friday";    }

case WORKDAY_ENUMERATORS WORKDAY_CASE_:

const char* get_day_text(Workday d)
{    
    switch (d)
    {
        BOOST_PP_SEQ_FOR_EACH(EXPAND_ENUM_CASE, WORKDAY, WORKDAY_ENUMERATORS)
    }
    return "WTF?!  That not a workday!";
}

WORKDAY_ENUMERATORS, .

, , , :

#undef WORKDAY_CASE_Monday
#undef WORKDAY_CASE_Tuesday
#undef WORKDAY_CASE_Wednesday
#undef WORKDAY_CASE_Thursday
#undef WORKDAY_CASE_Friday

, , , .

Answer 2

. C "" C, . , "enum". .

- , .

: , , Boost.Preprocessor. , , - Boost .

Answer 3

enum. . #define #ifdef.

Answer 4

, #define .h, ( .h , , ) . #define , - , ( #include ), #undef - , - , .. "case ENUM_foo: func_foo(); break;". func_ *, .