Front page | perl.perl5.porters |
Postings from June 2004
David Nicol <davidnicol@pay2send.com> writes:
>Attached is a patch to pp_sort.c that adds code to give a sortedness
>ratio in scalar context.
This looks like quite a big change for a return value which we seem
unable to reach consensus on.
(I would still like sort in scalar context to return min or max value
- don't care which because one can change cmp function to get the other.)
What can one use your sortedness value for?
>
>Empty and singleton arrays default to a sortedness ratio of 1.
>
>It currently appears to cause the last
>element of the array to be returned rather than the sv_newmortal
>loaded with the ratio, as desired.
>Because I don't understand how
>exactly pp_sort is returning its return value.
In the usual on the stack way ;-)
values returned are
stack[ORIGMARK+1 .. SP]
(There is a +1 on one end I may have it wrong way round...)
So where you have:
PL_stack_sp = ORIGMARK + (sorting_av ? 0 : max);
+ if(gimme==G_SCALAR)
+ {
+ SV *r = sv_newmortal();
+ sv_setnv(r,scalar_result);
+ XPUSHs(r);
+ };
You probably want something like:
PL_stack_sp = ORIGMARK;
if(gimme==G_SCALAR)
{
SV *r = sv_newmortal();
sv_setnv(r,scalar_result);
#if 0
SPAGAIN; # XPUSH is in terms of 'sp' not PL_stack_sp
XPUSHs(r);
PUTBACK; # get the sp back into PL_stack_sp
#else
/* don't need EXTEND? */
*++PL_stack_sp = r;
#endif
}
else {
PL_stack_sp += (sorting_av ? 0 : max);
}
May be better expressed in terms of MSPAGAIN?
But note that 'sorting_av' thing - what sets that?
>Help?
I suspect your stack pointer is in the wrong place.
In an array context list is "left" on the stack having been re-arranged.
In scalar case you need to adjust SP to that just your scalar is
returned.
>
>
>--
>davidnicol@pay2send.com
>"There's a fine line between participation and mockery" -- Scott Adams
>--- CURRENT/pp_sort.c 2004-03-16 12:42:23.000000000 -0600
>+++ ./BUILD_CURRENT/pp_sort.c 2004-06-07 22:22:32.000000000 -0500
>@@ -1423,14 +1423,18 @@
> OP* nextop = PL_op->op_next;
> I32 overloading = 0;
> bool hasargs = FALSE;
> I32 is_xsub = 0;
> I32 sorting_av = 0;
>+ I32 j,goodpairs;
>+ double scalar_result = 1.0;
>
> if (gimme != G_ARRAY) {
>- SP = MARK;
>- RETPUSHUNDEF;
>+ if ( gimme != G_SCALAR ){
>+ SP = MARK;
>+ RETPUSHUNDEF;
>+ };
> }
>
> ENTER;
> SAVEVPTR(PL_sortcop);
> if (PL_op->op_flags & OPf_STACKED) {
>@@ -1525,12 +1529,12 @@
> max--;
> }
> if (sorting_av)
> AvFILLp(av) = max-1;
>
>- if (max > 1) {
>- if (PL_sortcop) {
>+ if (max > 1) { /* max is number of elements */
>+ if (PL_sortcop) {
> PERL_CONTEXT *cx;
> SV** newsp;
> bool oldcatch = CATCH_GET;
>
> SAVETMPS;
>@@ -1565,19 +1569,41 @@
> cx->blk_sub.savearray = GvAV(PL_defgv);
> GvAV(PL_defgv) = (AV*)SvREFCNT_inc(av);
> CX_CURPAD_SAVE(cx->blk_sub);
> cx->blk_sub.argarray = av;
> }
>- sortsv(p1-max, max,
>+ if(gimme == G_ARRAY){
>+ sortsv(p1-max, max,
> is_xsub ? sortcv_xsub : hasargs ? sortcv_stacked : sortcv);
>-
>+ }
>+ else
>+ {
>+ /* sortednesssv(p1-max, max,
>+ is_xsub ? sortcv_xsub : hasargs ? sortcv_stacked : sortcv);
>+ */
>+ SV ** array;
>+ SVCOMPARE_t compare;
>+ array = p1-max;
>+ compare = (is_xsub ? sortcv_xsub : hasargs ? sortcv_stacked : sortcv);
>+ j = 0;
>+ goodpairs = 0;
>+ while (j < max){
>+ i = j++;
>+ if ((*compare)(aTHX_ array[i], array[j]) <= 0 )
>+ /* in order */
>+ goodpairs++;
>+ };
>+ scalar_result = (goodpairs / (max - 1));
>+ };
> POPBLOCK(cx,PL_curpm);
> PL_stack_sp = newsp;
> POPSTACK;
> CATCH_SET(oldcatch);
> }
>- else {
>+ else
>+ {
>+ if (gimme==G_ARRAY){
> MEXTEND(SP, 20); /* Can't afford stack realloc on signal. */
> sortsv(sorting_av ? AvARRAY(av) : ORIGMARK+1, max,
> (PL_op->op_private & OPpSORT_NUMERIC)
> ? ( (PL_op->op_private & OPpSORT_INTEGER)
> ? ( overloading ? amagic_i_ncmp : sv_i_ncmp)
>@@ -1586,19 +1612,56 @@
> ? ( overloading
> ? amagic_cmp_locale
> : sv_cmp_locale_static)
> : ( overloading ? amagic_cmp : sv_cmp_static)));
> if (PL_op->op_private & OPpSORT_REVERSE) {
>- SV **p = sorting_av ? AvARRAY(av) : ORIGMARK+1;
>+ SV **p = sorting_av ? AvARRAY(av) : ORIGMARK+1;
> SV **q = p+max-1;
> while (p < q) {
>- SV *tmp = *p;
>+ SV *tmp = *p;
> *p++ = *q;
> *q-- = tmp;
> }
> }
>- }
>+ }
>+ else /* gimme a G_SCALAR */
>+ {
>+ /*
>+ sortednesssv(sorting_av ? AvARRAY(av) : ORIGMARK+1, max,
>+ (PL_op->op_private & OPpSORT_NUMERIC)
>+ ? ( (PL_op->op_private & OPpSORT_INTEGER)
>+ ? ( overloading ? amagic_i_ncmp : sv_i_ncmp)
>+ : ( overloading ? amagic_ncmp : sv_ncmp))
>+ : ( IN_LOCALE_RUNTIME
>+ ? ( overloading
>+ ? amagic_cmp_locale
>+ : sv_cmp_locale_static)
>+ : ( overloading ? amagic_cmp : sv_cmp_static)));
>+ */
>+ SV ** array;
>+ SVCOMPARE_t compare;
>+ array = (sorting_av ? AvARRAY(av) : ORIGMARK+1);
>+ compare = ((PL_op->op_private & OPpSORT_NUMERIC)
>+ ? ( (PL_op->op_private & OPpSORT_INTEGER)
>+ ? ( overloading ? amagic_i_ncmp : sv_i_ncmp)
>+ : ( overloading ? amagic_ncmp : sv_ncmp))
>+ : ( IN_LOCALE_RUNTIME
>+ ? ( overloading
>+ ? amagic_cmp_locale
>+ : sv_cmp_locale_static)
>+ : ( overloading ? amagic_cmp : sv_cmp_static)));
>+ j = 0;
>+ goodpairs = 0;
>+ while (j < max){
>+ i = j++;
>+ if ((*compare)(aTHX_ array[i], array[j]) <= 0 )
>+ /* in order */
>+ goodpairs++;
>+ };
>+ scalar_result = (goodpairs / (max - 1));
>+ }
>+ }
> }
> if (av && !sorting_av) {
> /* simulate pp_aassign of tied AV */
> SV *sv;
> SV** base, **didstore;
>@@ -1615,13 +1678,19 @@
> if (SvSMAGICAL(sv))
> mg_set(sv);
> if (!didstore)
> sv_2mortal(sv);
> }
>- }
>+ };
> LEAVE;
> PL_stack_sp = ORIGMARK + (sorting_av ? 0 : max);
>+ if(gimme==G_SCALAR)
>+ {
>+ SV *r = sv_newmortal();
>+ sv_setnv(r,scalar_result);
>+ XPUSHs(r);
>+ };
> return nextop;
> }
>
> static I32
> sortcv(pTHX_ SV *a, SV *b)