[m-rev.] for review: MR_DEFINE_ENUM_CONST

[Fergus Henderson]

On 30-May-2001, David Jeffery <dgj at cs.mu.OZ.AU> wrote:
> Index: runtime/mercury_tags.h
> ===================================================================
> RCS file: /home/staff/zs/imp/mercury/runtime/mercury_tags.h,v
> retrieving revision 1.11
> diff -u -t -r1.11 mercury_tags.h
> --- runtime/mercury_tags.h	2001/03/18 23:10:13	1.11
> +++ runtime/mercury_tags.h	2001/05/30 05:28:03
> @@ -137,4 +137,23 @@
>  
>  #endif
>  
> +/*
> +** Convert an enumeration declaration into one which assigns the same
> +** values to the enumeration constants as Mercury's tag allocation scheme
> +** assigns. (This is necessary because in .rt grades Mercury enumerations are
> +** not assigned the same values as 'normal' C enumerations).
> +** 
> +*/
> +#ifdef MR_RESERVE_TAG
> +        #define MR_CONVERT_C_ENUM_CONSTANT(x) \
> +                MR_mkword(MR_mktag(MR_FIRST_UNRESERVED_RAW_TAG), MR_mkbody(x))
> +#else
> +        #define MR_CONVERT_C_ENUM_CONSTANT(x)   (x)
> +#endif
> +
> +#define MR_DEFINE_ENUM_CONST(x) \
> +        MR_PASTE2(x, _val),     \
> +        x = MR_CONVERT_C_ENUM_CONSTANT(MR_PASTE2(x, _val)), \
> +        MR_PASTE2(x, _dummy) = MR_PASTE2(x, _val)

I think you might as well put the MR_DEFINE_ENUM_CONST() inside the
#ifdef too, for the same reason that MR_CONVERT_C_ENUM_CONSTANT is
inside the #ifdef: making it easier to understand what happens in the
usual case.  In the #else case it can be just

           #define MR_DEFINE_ENUM_CONST(x)   (x)
	
can't it?

I think it might be slightly clearer to name MR_DEFINE_ENUM_CONST
as MR_DEFINE_MERCURY_ENUM_CONST.

Otherwise that change looks fine -- thanks.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
                                    |  of excellence is a lethal habit"
WWW: <http://www.cs.mu.oz.au/~fjh>  |     -- the last words of T. S. Garp.
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