Re: [boost] [preprocessor] Sequences vs. All Other Data Structures

Subject: Re: [boost] [preprocessor] Sequences vs. All Other Data Structures
From: Paul Mensonides (pmenso57_at_[hidden])
Date: 2012-04-27 01:06:58

On 4/26/2012 5:55 PM, Paul Mensonides wrote:
> Implementation of the above attached--probably lots of room for
> improvement and optimization. Apologies for the mega function (in
> particular--I didn't feel like refactoring) and the (non-portable) shell
> color-coding (I wanted to see blue paint). I built it with g++ 4.7.0,
> but I believe 4.6+ should also work.
>
> $ g++ -std=c++11 -I $CHAOS_ROOT 1.cpp

Updated attached.  This one executes some more realistic tests.

(I must say having no lexer to tokenize input and no parser to process 
directives makes input a pain in the ass.)

#define CAT(a, ...) PRIMITIVE_CAT(a, __VA_ARGS__)
#define PRIMITIVE_CAT(a, ...) a ## __VA_ARGS__

#define INC(x) PRIMITIVE_CAT(INC_, x)
#define INC_0 1
#define INC_1 2
#define INC_2 3
#define INC_3 4
#define INC_4 5
#define INC_5 6
#define INC_6 7
#define INC_7 8
#define INC_8 9
#define INC_9 9

#define DEC(x) PRIMITIVE_CAT(DEC_, x)
#define DEC_0 0
#define DEC_1 0
#define DEC_2 1
#define DEC_3 2
#define DEC_4 3
#define DEC_5 4
#define DEC_6 5
#define DEC_7 6
#define DEC_8 7
#define DEC_9 8

#define EXPR_S(s) PRIMITIVE_CAT(EXPR_, s)
#define EXPR_0(...) __VA_ARGS__
#define EXPR_1(...) __VA_ARGS__
#define EXPR_2(...) __VA_ARGS__
#define EXPR_3(...) __VA_ARGS__
#define EXPR_4(...) __VA_ARGS__
#define EXPR_5(...) __VA_ARGS__
#define EXPR_6(...) __VA_ARGS__
#define EXPR_7(...) __VA_ARGS__
#define EXPR_8(...) __VA_ARGS__
#define EXPR_9(...) __VA_ARGS__

#define SPLIT(i, ...) PRIMITIVE_CAT(SPLIT_, i)(, __VA_ARGS__)
#define SPLIT_0(p, a, ...) p ## a
#define SPLIT_1(p, a, ...) p ## __VA_ARGS__

#define IS_VARIADIC(...) \
     SPLIT(0, CAT(IS_VARIADIC_, IS_VARIADIC_C __VA_ARGS__)) \
     /**/
#define IS_VARIADIC_C(...) 1
#define IS_VARIADIC_IS_VARIADIC_C 0,
#define IS_VARIADIC_1 1,

#define NOT(x) IS_VARIADIC(PRIMITIVE_CAT(NOT_, x))
#define NOT_0 ()

#define COMPL(b) PRIMITIVE_CAT(COMPL_, b)
#define COMPL_0 1
#define COMPL_1 0

#define BOOL(x) COMPL(NOT(x))

#define IIF(c) PRIMITIVE_CAT(IIF_, c)
#define IIF_0(t, ...) __VA_ARGS__
#define IIF_1(t, ...) t

#define IF(c) IIF(BOOL(c))

#define EMPTY()

#define DEFER(id) id EMPTY()
#define OBSTRUCT(id) id DEFER(EMPTY)()

#define EAT(...)

#define REPEAT_S(s, n, m, ...) \
     IF(n)(REPEAT_I, EAT)(, OBSTRUCT(), INC(s), DEC(n), m, __VA_ARGS__) \
     /**/
#define REPEAT_INDIRECT() REPEAT_S
#define REPEAT_I(p, _, s, n, m, ...) \
     EXPR_S _(s)( \
         REPEAT_INDIRECT _()( \
             s, n, p ## m, p ## __VA_ARGS__ \
         ) \
         p ## m _(s, n, p ## __VA_ARGS__) \
     ) \
     /**/

#define COMMA() ,

#define COMMA_IF(n) IF(n)(COMMA, EAT)()

#define A(s, i, id) \
     COMMA_IF(i) \
     template<EXPR_S(s)(REPEAT_S(s, INC(i), B, ~))> class id ## i \
     /**/
#define B(s, i, _) COMMA_IF(i) class

EXPR_S(0)(REPEAT_S(0, 3, A, T))

The attached implementation yields correct results.

g++ yields

template< class> class T0 , template< class , class> class T1 , 
template< class , class , class> class T2

which is correct.

wave yields

template<class> class T0 , template<class , class> class T1 , 
template<class , class , class> class T2

which is correct.

Unsurprisingly, VC++ errors.

Regards,
Paul Mensonides