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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2018-09-21 20:50:18 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2018-09-21 20:50:41 -0400 |
| commit | 4f3b38fe2bde72d59b7eab593ff72e0cebd9ecc6 (patch) | |
| tree | 165c7c100f1a96f62c49bf72ba5e1d9670b5f329 /src/include/c.h | |
| parent | 1f7fc7670c7e0051b47bb4a4d6b41ff9e8af53fa (diff) | |
Get rid of explicit argument-count markings in tab-complete.c.
This replaces the "TailMatchesN" macros with just "TailMatches",
and likewise "HeadMatchesN" becomes "HeadMatches" and "MatchesN"
becomes "Matches". The various COMPLETE_WITH_LISTn macros are
reduced to COMPLETE_WITH, and the single-item COMPLETE_WITH_CONST
also gets folded into that. This eliminates a lot of minor
annoyance in writing tab-completion rules. Usefully, the compiled
code also gets a bit smaller (10% or so, on my machine).
The implementation depends on variadic macros, so we couldn't have
done this before we required C99.
Andres Freund and Thomas Munro; some cosmetic cleanup by me.
Discussion: https://postgr.es/m/d8jo9djvm7h.fsf@dalvik.ping.uio.no
Diffstat (limited to 'src/include/c.h')
| -rw-r--r-- | src/include/c.h | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/src/include/c.h b/src/include/c.h index 901d7911980..13c794d8eaa 100644 --- a/src/include/c.h +++ b/src/include/c.h @@ -225,6 +225,39 @@ #define CppConcat(x, y) x##y /* + * VA_ARGS_NARGS + * Returns the number of macro arguments it is passed. + * + * An empty argument still counts as an argument, so effectively, this is + * "one more than the number of commas in the argument list". + * + * This works for up to 63 arguments. Internally, VA_ARGS_NARGS_() is passed + * 64+N arguments, and the C99 standard only requires macros to allow up to + * 127 arguments, so we can't portably go higher. The implementation is + * pretty trivial: VA_ARGS_NARGS_() returns its 64th argument, and we set up + * the call so that that is the appropriate one of the list of constants. + * This idea is due to Laurent Deniau. + */ +#define VA_ARGS_NARGS(...) \ + VA_ARGS_NARGS_(__VA_ARGS__, \ + 63,62,61,60, \ + 59,58,57,56,55,54,53,52,51,50, \ + 49,48,47,46,45,44,43,42,41,40, \ + 39,38,37,36,35,34,33,32,31,30, \ + 29,28,27,26,25,24,23,22,21,20, \ + 19,18,17,16,15,14,13,12,11,10, \ + 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) +#define VA_ARGS_NARGS_( \ + _01,_02,_03,_04,_05,_06,_07,_08,_09,_10, \ + _11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \ + _21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \ + _31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \ + _41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \ + _51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \ + _61,_62,_63, N, ...) \ + (N) + +/* * dummyret is used to set return values in macros that use ?: to make * assignments. gcc wants these to be void, other compilers like char */ |