3 * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
4 * 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008 by Larry Wall and others
6 * You may distribute under the terms of either the GNU General Public
7 * License or the Artistic License, as specified in the README file.
12 * ...they shuffled back towards the rear of the line. 'No, not at the
13 * rear!' the slave-driver shouted. 'Three files up. And stay there...
15 * [p.931 of _The Lord of the Rings_, VI/ii: "The Land of Shadow"]
18 /* This file contains pp ("push/pop") functions that
19 * execute the opcodes that make up a perl program. A typical pp function
20 * expects to find its arguments on the stack, and usually pushes its
21 * results onto the stack, hence the 'pp' terminology. Each OP structure
22 * contains a pointer to the relevant pp_foo() function.
24 * This particular file just contains pp_sort(), which is complex
25 * enough to merit its own file! See the other pp*.c files for the rest of
30 #define PERL_IN_PP_SORT_C
34 /* looks like 'small' is reserved word for WINCE (or somesuch)*/
38 #define sv_cmp_static Perl_sv_cmp
39 #define sv_cmp_locale_static Perl_sv_cmp_locale
42 #define SMALLSORT (200)
45 /* Flags for qsortsv and mergesortsv */
47 #define SORTf_STABLE 2
51 * The mergesort implementation is by Peter M. Mcilroy <pmcilroy@lucent.com>.
53 * The original code was written in conjunction with BSD Computer Software
54 * Research Group at University of California, Berkeley.
56 * See also: "Optimistic Sorting and Information Theoretic Complexity"
58 * SODA (Fourth Annual ACM-SIAM Symposium on Discrete Algorithms),
59 * pp 467-474, Austin, Texas, 25-27 January 1993.
61 * The integration to Perl is by John P. Linderman <jpl.jpl@gmail.com>.
63 * The code can be distributed under the same terms as Perl itself.
68 typedef char * aptr; /* pointer for arithmetic on sizes */
69 typedef SV * gptr; /* pointers in our lists */
71 /* Binary merge internal sort, with a few special mods
72 ** for the special perl environment it now finds itself in.
74 ** Things that were once options have been hotwired
75 ** to values suitable for this use. In particular, we'll always
76 ** initialize looking for natural runs, we'll always produce stable
77 ** output, and we'll always do Peter McIlroy's binary merge.
80 /* Pointer types for arithmetic and storage and convenience casts */
82 #define APTR(P) ((aptr)(P))
83 #define GPTP(P) ((gptr *)(P))
84 #define GPPP(P) ((gptr **)(P))
87 /* byte offset from pointer P to (larger) pointer Q */
88 #define BYTEOFF(P, Q) (APTR(Q) - APTR(P))
90 #define PSIZE sizeof(gptr)
92 /* If PSIZE is power of 2, make PSHIFT that power, if that helps */
95 #define PNELEM(P, Q) (BYTEOFF(P,Q) >> (PSHIFT))
96 #define PNBYTE(N) ((N) << (PSHIFT))
97 #define PINDEX(P, N) (GPTP(APTR(P) + PNBYTE(N)))
99 /* Leave optimization to compiler */
100 #define PNELEM(P, Q) (GPTP(Q) - GPTP(P))
101 #define PNBYTE(N) ((N) * (PSIZE))
102 #define PINDEX(P, N) (GPTP(P) + (N))
105 /* Pointer into other corresponding to pointer into this */
106 #define POTHER(P, THIS, OTHER) GPTP(APTR(OTHER) + BYTEOFF(THIS,P))
108 #define FROMTOUPTO(src, dst, lim) do *dst++ = *src++; while(src<lim)
111 /* Runs are identified by a pointer in the auxiliary list.
112 ** The pointer is at the start of the list,
113 ** and it points to the start of the next list.
114 ** NEXT is used as an lvalue, too.
117 #define NEXT(P) (*GPPP(P))
120 /* PTHRESH is the minimum number of pairs with the same sense to justify
121 ** checking for a run and extending it. Note that PTHRESH counts PAIRS,
122 ** not just elements, so PTHRESH == 8 means a run of 16.
127 /* RTHRESH is the number of elements in a run that must compare low
128 ** to the low element from the opposing run before we justify
129 ** doing a binary rampup instead of single stepping.
130 ** In random input, N in a row low should only happen with
131 ** probability 2^(1-N), so we can risk that we are dealing
132 ** with orderly input without paying much when we aren't.
139 ** Overview of algorithm and variables.
140 ** The array of elements at list1 will be organized into runs of length 2,
141 ** or runs of length >= 2 * PTHRESH. We only try to form long runs when
142 ** PTHRESH adjacent pairs compare in the same way, suggesting overall order.
144 ** Unless otherwise specified, pair pointers address the first of two elements.
146 ** b and b+1 are a pair that compare with sense "sense".
147 ** b is the "bottom" of adjacent pairs that might form a longer run.
149 ** p2 parallels b in the list2 array, where runs are defined by
152 ** t represents the "top" of the adjacent pairs that might extend
153 ** the run beginning at b. Usually, t addresses a pair
154 ** that compares with opposite sense from (b,b+1).
155 ** However, it may also address a singleton element at the end of list1,
156 ** or it may be equal to "last", the first element beyond list1.
158 ** r addresses the Nth pair following b. If this would be beyond t,
159 ** we back it off to t. Only when r is less than t do we consider the
160 ** run long enough to consider checking.
162 ** q addresses a pair such that the pairs at b through q already form a run.
163 ** Often, q will equal b, indicating we only are sure of the pair itself.
164 ** However, a search on the previous cycle may have revealed a longer run,
165 ** so q may be greater than b.
167 ** p is used to work back from a candidate r, trying to reach q,
168 ** which would mean b through r would be a run. If we discover such a run,
169 ** we start q at r and try to push it further towards t.
170 ** If b through r is NOT a run, we detect the wrong order at (p-1,p).
171 ** In any event, after the check (if any), we have two main cases.
173 ** 1) Short run. b <= q < p <= r <= t.
174 ** b through q is a run (perhaps trivial)
175 ** q through p are uninteresting pairs
176 ** p through r is a run
178 ** 2) Long run. b < r <= q < t.
179 ** b through q is a run (of length >= 2 * PTHRESH)
181 ** Note that degenerate cases are not only possible, but likely.
182 ** For example, if the pair following b compares with opposite sense,
183 ** then b == q < p == r == t.
188 dynprep(pTHX_ gptr *list1, gptr *list2, size_t nmemb, const SVCOMPARE_t cmp)
191 gptr *b, *p, *q, *t, *p2;
196 last = PINDEX(b, nmemb);
197 sense = (cmp(aTHX_ *b, *(b+1)) > 0);
198 for (p2 = list2; b < last; ) {
199 /* We just started, or just reversed sense.
200 ** Set t at end of pairs with the prevailing sense.
202 for (p = b+2, t = p; ++p < last; t = ++p) {
203 if ((cmp(aTHX_ *t, *p) > 0) != sense) break;
206 /* Having laid out the playing field, look for long runs */
208 p = r = b + (2 * PTHRESH);
209 if (r >= t) p = r = t; /* too short to care about */
211 while (((cmp(aTHX_ *(p-1), *p) > 0) == sense) &&
214 /* b through r is a (long) run.
215 ** Extend it as far as possible.
218 while (((p += 2) < t) &&
219 ((cmp(aTHX_ *(p-1), *p) > 0) == sense)) q = p;
220 r = p = q + 2; /* no simple pairs, no after-run */
223 if (q > b) { /* run of greater than 2 at b */
227 /* pick up singleton, if possible */
230 ((cmp(aTHX_ *(p-1), *p) > 0) == sense))
231 savep = r = p = q = last;
232 p2 = NEXT(p2) = p2 + (p - b); ++runs;
241 while (q < p) { /* simple pairs */
242 p2 = NEXT(p2) = p2 + 2; ++runs;
249 if (((b = p) == t) && ((t+1) == last)) {
250 NEXT(p2) = p2 + 1; ++runs;
261 /* The original merge sort, in use since 5.7, was as fast as, or faster than,
262 * qsort on many platforms, but slower than qsort, conspicuously so,
263 * on others. The most likely explanation was platform-specific
264 * differences in cache sizes and relative speeds.
266 * The quicksort divide-and-conquer algorithm guarantees that, as the
267 * problem is subdivided into smaller and smaller parts, the parts
268 * fit into smaller (and faster) caches. So it doesn't matter how
269 * many levels of cache exist, quicksort will "find" them, and,
270 * as long as smaller is faster, take advantage of them.
272 * By contrast, consider how the original mergesort algorithm worked.
273 * Suppose we have five runs (each typically of length 2 after dynprep).
282 * Adjacent pairs are merged in "grand sweeps" through the input.
283 * This means, on pass 1, the records in runs 1 and 2 aren't revisited until
284 * runs 3 and 4 are merged and the runs from run 5 have been copied.
285 * The only cache that matters is one large enough to hold *all* the input.
286 * On some platforms, this may be many times slower than smaller caches.
288 * The following pseudo-code uses the same basic merge algorithm,
289 * but in a divide-and-conquer way.
291 * # merge $runs runs at offset $offset of list $list1 into $list2.
292 * # all unmerged runs ($runs == 1) originate in list $base.
294 * my ($offset, $runs, $base, $list1, $list2) = @_;
297 * if ($list1 is $base) copy run to $list2
298 * return offset of end of list (or copy)
300 * $off2 = mgsort2($offset, $runs-($runs/2), $base, $list2, $list1)
301 * mgsort2($off2, $runs/2, $base, $list2, $list1)
302 * merge the adjacent runs at $offset of $list1 into $list2
303 * return the offset of the end of the merged runs
306 * mgsort2(0, $runs, $base, $aux, $base);
308 * For our 5 runs, the tree of calls looks like
317 * and the corresponding activity looks like
319 * copy runs 1 and 2 from base to aux
320 * merge runs 1 and 2 from aux to base
321 * (run 3 is where it belongs, no copy needed)
322 * merge runs 12 and 3 from base to aux
323 * (runs 4 and 5 are where they belong, no copy needed)
324 * merge runs 4 and 5 from base to aux
325 * merge runs 123 and 45 from aux to base
327 * Note that we merge runs 1 and 2 immediately after copying them,
328 * while they are still likely to be in fast cache. Similarly,
329 * run 3 is merged with run 12 while it still may be lingering in cache.
330 * This implementation should therefore enjoy much of the cache-friendly
331 * behavior that quicksort does. In addition, it does less copying
332 * than the original mergesort implementation (only runs 1 and 2 are copied)
333 * and the "balancing" of merges is better (merged runs comprise more nearly
334 * equal numbers of original runs).
336 * The actual cache-friendly implementation will use a pseudo-stack
337 * to avoid recursion, and will unroll processing of runs of length 2,
338 * but it is otherwise similar to the recursive implementation.
342 IV offset; /* offset of 1st of 2 runs at this level */
343 IV runs; /* how many runs must be combined into 1 */
344 } off_runs; /* pseudo-stack element */
348 cmp_desc(pTHX_ gptr const a, gptr const b)
351 return -PL_sort_RealCmp(aTHX_ a, b);
355 S_mergesortsv(pTHX_ gptr *base, size_t nmemb, SVCOMPARE_t cmp, U32 flags)
360 gptr *f1, *f2, *t, *b, *p;
364 gptr small[SMALLSORT];
366 off_runs stack[60], *stackp;
367 SVCOMPARE_t savecmp = NULL;
369 if (nmemb <= 1) return; /* sorted trivially */
371 if ((flags & SORTf_DESC) != 0) {
372 savecmp = PL_sort_RealCmp; /* Save current comparison routine, if any */
373 PL_sort_RealCmp = cmp; /* Put comparison routine where cmp_desc can find it */
377 if (nmemb <= SMALLSORT) aux = small; /* use stack for aux array */
378 else { Newx(aux,nmemb,gptr); } /* allocate auxiliary array */
381 stackp->runs = dynprep(aTHX_ base, aux, nmemb, cmp);
382 stackp->offset = offset = 0;
383 which[0] = which[2] = base;
386 /* On levels where both runs have be constructed (stackp->runs == 0),
387 * merge them, and note the offset of their end, in case the offset
388 * is needed at the next level up. Hop up a level, and,
389 * as long as stackp->runs is 0, keep merging.
391 IV runs = stackp->runs;
395 list1 = which[iwhich]; /* area where runs are now */
396 list2 = which[++iwhich]; /* area for merged runs */
399 offset = stackp->offset;
400 f1 = p1 = list1 + offset; /* start of first run */
401 p = tp2 = list2 + offset; /* where merged run will go */
402 t = NEXT(p); /* where first run ends */
403 f2 = l1 = POTHER(t, list2, list1); /* ... on the other side */
404 t = NEXT(t); /* where second runs ends */
405 l2 = POTHER(t, list2, list1); /* ... on the other side */
406 offset = PNELEM(list2, t);
407 while (f1 < l1 && f2 < l2) {
408 /* If head 1 is larger than head 2, find ALL the elements
409 ** in list 2 strictly less than head1, write them all,
410 ** then head 1. Then compare the new heads, and repeat,
411 ** until one or both lists are exhausted.
413 ** In all comparisons (after establishing
414 ** which head to merge) the item to merge
415 ** (at pointer q) is the first operand of
416 ** the comparison. When we want to know
417 ** if "q is strictly less than the other",
420 ** because stability demands that we treat equality
421 ** as high when q comes from l2, and as low when
422 ** q was from l1. So we ask the question by doing
423 ** cmp(q, other) <= sense
424 ** and make sense == 0 when equality should look low,
425 ** and -1 when equality should look high.
429 if (cmp(aTHX_ *f1, *f2) <= 0) {
430 q = f2; b = f1; t = l1;
433 q = f1; b = f2; t = l2;
440 ** Leave t at something strictly
441 ** greater than q (or at the end of the list),
442 ** and b at something strictly less than q.
444 for (i = 1, run = 0 ;;) {
445 if ((p = PINDEX(b, i)) >= t) {
447 if (((p = PINDEX(t, -1)) > b) &&
448 (cmp(aTHX_ *q, *p) <= sense))
452 } else if (cmp(aTHX_ *q, *p) <= sense) {
456 if (++run >= RTHRESH) i += i;
460 /* q is known to follow b and must be inserted before t.
461 ** Increment b, so the range of possibilities is [b,t).
462 ** Round binary split down, to favor early appearance.
463 ** Adjust b and t until q belongs just before t.
468 p = PINDEX(b, (PNELEM(b, t) - 1) / 2);
469 if (cmp(aTHX_ *q, *p) <= sense) {
475 /* Copy all the strictly low elements */
478 FROMTOUPTO(f2, tp2, t);
481 FROMTOUPTO(f1, tp2, t);
487 /* Run out remaining list */
489 if (f2 < l2) FROMTOUPTO(f2, tp2, l2);
490 } else FROMTOUPTO(f1, tp2, l1);
491 p1 = NEXT(p1) = POTHER(tp2, list2, list1);
493 if (--level == 0) goto done;
495 t = list1; list1 = list2; list2 = t; /* swap lists */
496 } while ((runs = stackp->runs) == 0);
500 stackp->runs = 0; /* current run will finish level */
501 /* While there are more than 2 runs remaining,
502 * turn them into exactly 2 runs (at the "other" level),
503 * each made up of approximately half the runs.
504 * Stack the second half for later processing,
505 * and set about producing the first half now.
510 stackp->offset = offset;
511 runs -= stackp->runs = runs / 2;
513 /* We must construct a single run from 1 or 2 runs.
514 * All the original runs are in which[0] == base.
515 * The run we construct must end up in which[level&1].
519 /* Constructing a single run from a single run.
520 * If it's where it belongs already, there's nothing to do.
521 * Otherwise, copy it to where it belongs.
522 * A run of 1 is either a singleton at level 0,
523 * or the second half of a split 3. In neither event
524 * is it necessary to set offset. It will be set by the merge
525 * that immediately follows.
527 if (iwhich) { /* Belongs in aux, currently in base */
528 f1 = b = PINDEX(base, offset); /* where list starts */
529 f2 = PINDEX(aux, offset); /* where list goes */
530 t = NEXT(f2); /* where list will end */
531 offset = PNELEM(aux, t); /* offset thereof */
532 t = PINDEX(base, offset); /* where it currently ends */
533 FROMTOUPTO(f1, f2, t); /* copy */
534 NEXT(b) = t; /* set up parallel pointer */
535 } else if (level == 0) goto done; /* single run at level 0 */
537 /* Constructing a single run from two runs.
538 * The merge code at the top will do that.
539 * We need only make sure the two runs are in the "other" array,
540 * so they'll end up in the correct array after the merge.
544 stackp->offset = offset;
545 stackp->runs = 0; /* take care of both runs, trigger merge */
546 if (!iwhich) { /* Merged runs belong in aux, copy 1st */
547 f1 = b = PINDEX(base, offset); /* where first run starts */
548 f2 = PINDEX(aux, offset); /* where it will be copied */
549 t = NEXT(f2); /* where first run will end */
550 offset = PNELEM(aux, t); /* offset thereof */
551 p = PINDEX(base, offset); /* end of first run */
552 t = NEXT(t); /* where second run will end */
553 t = PINDEX(base, PNELEM(aux, t)); /* where it now ends */
554 FROMTOUPTO(f1, f2, t); /* copy both runs */
555 NEXT(b) = p; /* paralleled pointer for 1st */
556 NEXT(p) = t; /* ... and for second */
561 if (aux != small) Safefree(aux); /* free iff allocated */
563 PL_sort_RealCmp = savecmp; /* Restore current comparison routine, if any */
569 * The quicksort implementation was derived from source code contributed
572 * NOTE: this code was derived from Tom Horsley's qsort replacement
573 * and should not be confused with the original code.
576 /* Copyright (C) Tom Horsley, 1997. All rights reserved.
578 Permission granted to distribute under the same terms as perl which are
581 This program is free software; you can redistribute it and/or modify
582 it under the terms of either:
584 a) the GNU General Public License as published by the Free
585 Software Foundation; either version 1, or (at your option) any
588 b) the "Artistic License" which comes with this Kit.
590 Details on the perl license can be found in the perl source code which
591 may be located via the www.perl.com web page.
593 This is the most wonderfulest possible qsort I can come up with (and
594 still be mostly portable) My (limited) tests indicate it consistently
595 does about 20% fewer calls to compare than does the qsort in the Visual
596 C++ library, other vendors may vary.
598 Some of the ideas in here can be found in "Algorithms" by Sedgewick,
599 others I invented myself (or more likely re-invented since they seemed
600 pretty obvious once I watched the algorithm operate for a while).
602 Most of this code was written while watching the Marlins sweep the Giants
603 in the 1997 National League Playoffs - no Braves fans allowed to use this
604 code (just kidding :-).
606 I realize that if I wanted to be true to the perl tradition, the only
607 comment in this file would be something like:
609 ...they shuffled back towards the rear of the line. 'No, not at the
610 rear!' the slave-driver shouted. 'Three files up. And stay there...
612 However, I really needed to violate that tradition just so I could keep
613 track of what happens myself, not to mention some poor fool trying to
614 understand this years from now :-).
617 /* ********************************************************** Configuration */
619 #ifndef QSORT_ORDER_GUESS
620 #define QSORT_ORDER_GUESS 2 /* Select doubling version of the netBSD trick */
623 /* QSORT_MAX_STACK is the largest number of partitions that can be stacked up for
624 future processing - a good max upper bound is log base 2 of memory size
625 (32 on 32 bit machines, 64 on 64 bit machines, etc). In reality can
626 safely be smaller than that since the program is taking up some space and
627 most operating systems only let you grab some subset of contiguous
628 memory (not to mention that you are normally sorting data larger than
629 1 byte element size :-).
631 #ifndef QSORT_MAX_STACK
632 #define QSORT_MAX_STACK 32
635 /* QSORT_BREAK_EVEN is the size of the largest partition we should insertion sort.
636 Anything bigger and we use qsort. If you make this too small, the qsort
637 will probably break (or become less efficient), because it doesn't expect
638 the middle element of a partition to be the same as the right or left -
639 you have been warned).
641 #ifndef QSORT_BREAK_EVEN
642 #define QSORT_BREAK_EVEN 6
645 /* QSORT_PLAY_SAFE is the size of the largest partition we're willing
646 to go quadratic on. We innoculate larger partitions against
647 quadratic behavior by shuffling them before sorting. This is not
648 an absolute guarantee of non-quadratic behavior, but it would take
649 staggeringly bad luck to pick extreme elements as the pivot
650 from randomized data.
652 #ifndef QSORT_PLAY_SAFE
653 #define QSORT_PLAY_SAFE 255
656 /* ************************************************************* Data Types */
658 /* hold left and right index values of a partition waiting to be sorted (the
659 partition includes both left and right - right is NOT one past the end or
662 struct partition_stack_entry {
665 #ifdef QSORT_ORDER_GUESS
666 int qsort_break_even;
670 /* ******************************************************* Shorthand Macros */
672 /* Note that these macros will be used from inside the qsort function where
673 we happen to know that the variable 'elt_size' contains the size of an
674 array element and the variable 'temp' points to enough space to hold a
675 temp element and the variable 'array' points to the array being sorted
676 and 'compare' is the pointer to the compare routine.
678 Also note that there are very many highly architecture specific ways
679 these might be sped up, but this is simply the most generally portable
680 code I could think of.
683 /* Return < 0 == 0 or > 0 as the value of elt1 is < elt2, == elt2, > elt2
685 #define qsort_cmp(elt1, elt2) \
686 ((*compare)(aTHX_ array[elt1], array[elt2]))
688 #ifdef QSORT_ORDER_GUESS
689 #define QSORT_NOTICE_SWAP swapped++;
691 #define QSORT_NOTICE_SWAP
694 /* swaps contents of array elements elt1, elt2.
696 #define qsort_swap(elt1, elt2) \
699 temp = array[elt1]; \
700 array[elt1] = array[elt2]; \
701 array[elt2] = temp; \
704 /* rotate contents of elt1, elt2, elt3 such that elt1 gets elt2, elt2 gets
705 elt3 and elt3 gets elt1.
707 #define qsort_rotate(elt1, elt2, elt3) \
710 temp = array[elt1]; \
711 array[elt1] = array[elt2]; \
712 array[elt2] = array[elt3]; \
713 array[elt3] = temp; \
716 /* ************************************************************ Debug stuff */
723 return; /* good place to set a breakpoint */
726 #define qsort_assert(t) (void)( (t) || (break_here(), 0) )
733 int (*compare)(const void * elt1, const void * elt2),
734 int pc_left, int pc_right, int u_left, int u_right)
738 qsort_assert(pc_left <= pc_right);
739 qsort_assert(u_right < pc_left);
740 qsort_assert(pc_right < u_left);
741 for (i = u_right + 1; i < pc_left; ++i) {
742 qsort_assert(qsort_cmp(i, pc_left) < 0);
744 for (i = pc_left; i < pc_right; ++i) {
745 qsort_assert(qsort_cmp(i, pc_right) == 0);
747 for (i = pc_right + 1; i < u_left; ++i) {
748 qsort_assert(qsort_cmp(pc_right, i) < 0);
752 #define qsort_all_asserts(PC_LEFT, PC_RIGHT, U_LEFT, U_RIGHT) \
753 doqsort_all_asserts(array, num_elts, elt_size, compare, \
754 PC_LEFT, PC_RIGHT, U_LEFT, U_RIGHT)
758 #define qsort_assert(t) ((void)0)
760 #define qsort_all_asserts(PC_LEFT, PC_RIGHT, U_LEFT, U_RIGHT) ((void)0)
764 /* ****************************************************************** qsort */
766 STATIC void /* the standard unstable (u) quicksort (qsort) */
767 S_qsortsvu(pTHX_ SV ** array, size_t num_elts, SVCOMPARE_t compare)
770 struct partition_stack_entry partition_stack[QSORT_MAX_STACK];
771 int next_stack_entry = 0;
774 #ifdef QSORT_ORDER_GUESS
775 int qsort_break_even;
779 PERL_ARGS_ASSERT_QSORTSVU;
781 /* Make sure we actually have work to do.
787 /* Inoculate large partitions against quadratic behavior */
788 if (num_elts > QSORT_PLAY_SAFE) {
790 SV ** const q = array;
791 for (n = num_elts; n > 1; ) {
792 const size_t j = (size_t)(n-- * Drand01());
799 /* Setup the initial partition definition and fall into the sorting loop
802 part_right = (int)(num_elts - 1);
803 #ifdef QSORT_ORDER_GUESS
804 qsort_break_even = QSORT_BREAK_EVEN;
806 #define qsort_break_even QSORT_BREAK_EVEN
809 if ((part_right - part_left) >= qsort_break_even) {
810 /* OK, this is gonna get hairy, so lets try to document all the
811 concepts and abbreviations and variables and what they keep
814 pc: pivot chunk - the set of array elements we accumulate in the
815 middle of the partition, all equal in value to the original
816 pivot element selected. The pc is defined by:
818 pc_left - the leftmost array index of the pc
819 pc_right - the rightmost array index of the pc
821 we start with pc_left == pc_right and only one element
822 in the pivot chunk (but it can grow during the scan).
824 u: uncompared elements - the set of elements in the partition
825 we have not yet compared to the pivot value. There are two
826 uncompared sets during the scan - one to the left of the pc
827 and one to the right.
829 u_right - the rightmost index of the left side's uncompared set
830 u_left - the leftmost index of the right side's uncompared set
832 The leftmost index of the left sides's uncompared set
833 doesn't need its own variable because it is always defined
834 by the leftmost edge of the whole partition (part_left). The
835 same goes for the rightmost edge of the right partition
838 We know there are no uncompared elements on the left once we
839 get u_right < part_left and no uncompared elements on the
840 right once u_left > part_right. When both these conditions
841 are met, we have completed the scan of the partition.
843 Any elements which are between the pivot chunk and the
844 uncompared elements should be less than the pivot value on
845 the left side and greater than the pivot value on the right
846 side (in fact, the goal of the whole algorithm is to arrange
847 for that to be true and make the groups of less-than and
848 greater-then elements into new partitions to sort again).
850 As you marvel at the complexity of the code and wonder why it
851 has to be so confusing. Consider some of the things this level
854 Once I do a compare, I squeeze every ounce of juice out of it. I
855 never do compare calls I don't have to do, and I certainly never
858 I also never swap any elements unless I can prove there is a
859 good reason. Many sort algorithms will swap a known value with
860 an uncompared value just to get things in the right place (or
861 avoid complexity :-), but that uncompared value, once it gets
862 compared, may then have to be swapped again. A lot of the
863 complexity of this code is due to the fact that it never swaps
864 anything except compared values, and it only swaps them when the
865 compare shows they are out of position.
867 int pc_left, pc_right;
872 pc_left = ((part_left + part_right) / 2);
874 u_right = pc_left - 1;
875 u_left = pc_right + 1;
877 /* Qsort works best when the pivot value is also the median value
878 in the partition (unfortunately you can't find the median value
879 without first sorting :-), so to give the algorithm a helping
880 hand, we pick 3 elements and sort them and use the median value
881 of that tiny set as the pivot value.
883 Some versions of qsort like to use the left middle and right as
884 the 3 elements to sort so they can insure the ends of the
885 partition will contain values which will stop the scan in the
886 compare loop, but when you have to call an arbitrarily complex
887 routine to do a compare, its really better to just keep track of
888 array index values to know when you hit the edge of the
889 partition and avoid the extra compare. An even better reason to
890 avoid using a compare call is the fact that you can drop off the
891 edge of the array if someone foolishly provides you with an
892 unstable compare function that doesn't always provide consistent
895 So, since it is simpler for us to compare the three adjacent
896 elements in the middle of the partition, those are the ones we
897 pick here (conveniently pointed at by u_right, pc_left, and
898 u_left). The values of the left, center, and right elements
899 are refered to as l c and r in the following comments.
902 #ifdef QSORT_ORDER_GUESS
905 s = qsort_cmp(u_right, pc_left);
908 s = qsort_cmp(pc_left, u_left);
909 /* if l < c, c < r - already in order - nothing to do */
911 /* l < c, c == r - already in order, pc grows */
913 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
915 /* l < c, c > r - need to know more */
916 s = qsort_cmp(u_right, u_left);
918 /* l < c, c > r, l < r - swap c & r to get ordered */
919 qsort_swap(pc_left, u_left);
920 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
922 /* l < c, c > r, l == r - swap c&r, grow pc */
923 qsort_swap(pc_left, u_left);
925 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
927 /* l < c, c > r, l > r - make lcr into rlc to get ordered */
928 qsort_rotate(pc_left, u_right, u_left);
929 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
934 s = qsort_cmp(pc_left, u_left);
936 /* l == c, c < r - already in order, grow pc */
938 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
940 /* l == c, c == r - already in order, grow pc both ways */
943 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
945 /* l == c, c > r - swap l & r, grow pc */
946 qsort_swap(u_right, u_left);
948 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
952 s = qsort_cmp(pc_left, u_left);
954 /* l > c, c < r - need to know more */
955 s = qsort_cmp(u_right, u_left);
957 /* l > c, c < r, l < r - swap l & c to get ordered */
958 qsort_swap(u_right, pc_left);
959 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
961 /* l > c, c < r, l == r - swap l & c, grow pc */
962 qsort_swap(u_right, pc_left);
964 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
966 /* l > c, c < r, l > r - rotate lcr into crl to order */
967 qsort_rotate(u_right, pc_left, u_left);
968 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
971 /* l > c, c == r - swap ends, grow pc */
972 qsort_swap(u_right, u_left);
974 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
976 /* l > c, c > r - swap ends to get in order */
977 qsort_swap(u_right, u_left);
978 qsort_all_asserts(pc_left, pc_right, u_left + 1, u_right - 1);
981 /* We now know the 3 middle elements have been compared and
982 arranged in the desired order, so we can shrink the uncompared
987 qsort_all_asserts(pc_left, pc_right, u_left, u_right);
989 /* The above massive nested if was the simple part :-). We now have
990 the middle 3 elements ordered and we need to scan through the
991 uncompared sets on either side, swapping elements that are on
992 the wrong side or simply shuffling equal elements around to get
993 all equal elements into the pivot chunk.
997 int still_work_on_left;
998 int still_work_on_right;
1000 /* Scan the uncompared values on the left. If I find a value
1001 equal to the pivot value, move it over so it is adjacent to
1002 the pivot chunk and expand the pivot chunk. If I find a value
1003 less than the pivot value, then just leave it - its already
1004 on the correct side of the partition. If I find a greater
1005 value, then stop the scan.
1007 while ((still_work_on_left = (u_right >= part_left))) {
1008 s = qsort_cmp(u_right, pc_left);
1011 } else if (s == 0) {
1013 if (pc_left != u_right) {
1014 qsort_swap(u_right, pc_left);
1020 qsort_assert(u_right < pc_left);
1021 qsort_assert(pc_left <= pc_right);
1022 qsort_assert(qsort_cmp(u_right + 1, pc_left) <= 0);
1023 qsort_assert(qsort_cmp(pc_left, pc_right) == 0);
1026 /* Do a mirror image scan of uncompared values on the right
1028 while ((still_work_on_right = (u_left <= part_right))) {
1029 s = qsort_cmp(pc_right, u_left);
1032 } else if (s == 0) {
1034 if (pc_right != u_left) {
1035 qsort_swap(pc_right, u_left);
1041 qsort_assert(u_left > pc_right);
1042 qsort_assert(pc_left <= pc_right);
1043 qsort_assert(qsort_cmp(pc_right, u_left - 1) <= 0);
1044 qsort_assert(qsort_cmp(pc_left, pc_right) == 0);
1047 if (still_work_on_left) {
1048 /* I know I have a value on the left side which needs to be
1049 on the right side, but I need to know more to decide
1050 exactly the best thing to do with it.
1052 if (still_work_on_right) {
1053 /* I know I have values on both side which are out of
1054 position. This is a big win because I kill two birds
1055 with one swap (so to speak). I can advance the
1056 uncompared pointers on both sides after swapping both
1057 of them into the right place.
1059 qsort_swap(u_right, u_left);
1062 qsort_all_asserts(pc_left, pc_right, u_left, u_right);
1064 /* I have an out of position value on the left, but the
1065 right is fully scanned, so I "slide" the pivot chunk
1066 and any less-than values left one to make room for the
1067 greater value over on the right. If the out of position
1068 value is immediately adjacent to the pivot chunk (there
1069 are no less-than values), I can do that with a swap,
1070 otherwise, I have to rotate one of the less than values
1071 into the former position of the out of position value
1072 and the right end of the pivot chunk into the left end
1076 if (pc_left == u_right) {
1077 qsort_swap(u_right, pc_right);
1078 qsort_all_asserts(pc_left, pc_right-1, u_left, u_right-1);
1080 qsort_rotate(u_right, pc_left, pc_right);
1081 qsort_all_asserts(pc_left, pc_right-1, u_left, u_right-1);
1086 } else if (still_work_on_right) {
1087 /* Mirror image of complex case above: I have an out of
1088 position value on the right, but the left is fully
1089 scanned, so I need to shuffle things around to make room
1090 for the right value on the left.
1093 if (pc_right == u_left) {
1094 qsort_swap(u_left, pc_left);
1095 qsort_all_asserts(pc_left+1, pc_right, u_left+1, u_right);
1097 qsort_rotate(pc_right, pc_left, u_left);
1098 qsort_all_asserts(pc_left+1, pc_right, u_left+1, u_right);
1103 /* No more scanning required on either side of partition,
1104 break out of loop and figure out next set of partitions
1110 /* The elements in the pivot chunk are now in the right place. They
1111 will never move or be compared again. All I have to do is decide
1112 what to do with the stuff to the left and right of the pivot
1115 Notes on the QSORT_ORDER_GUESS ifdef code:
1117 1. If I just built these partitions without swapping any (or
1118 very many) elements, there is a chance that the elements are
1119 already ordered properly (being properly ordered will
1120 certainly result in no swapping, but the converse can't be
1123 2. A (properly written) insertion sort will run faster on
1124 already ordered data than qsort will.
1126 3. Perhaps there is some way to make a good guess about
1127 switching to an insertion sort earlier than partition size 6
1128 (for instance - we could save the partition size on the stack
1129 and increase the size each time we find we didn't swap, thus
1130 switching to insertion sort earlier for partitions with a
1131 history of not swapping).
1133 4. Naturally, if I just switch right away, it will make
1134 artificial benchmarks with pure ascending (or descending)
1135 data look really good, but is that a good reason in general?
1139 #ifdef QSORT_ORDER_GUESS
1141 #if QSORT_ORDER_GUESS == 1
1142 qsort_break_even = (part_right - part_left) + 1;
1144 #if QSORT_ORDER_GUESS == 2
1145 qsort_break_even *= 2;
1147 #if QSORT_ORDER_GUESS == 3
1148 const int prev_break = qsort_break_even;
1149 qsort_break_even *= qsort_break_even;
1150 if (qsort_break_even < prev_break) {
1151 qsort_break_even = (part_right - part_left) + 1;
1155 qsort_break_even = QSORT_BREAK_EVEN;
1159 if (part_left < pc_left) {
1160 /* There are elements on the left which need more processing.
1161 Check the right as well before deciding what to do.
1163 if (pc_right < part_right) {
1164 /* We have two partitions to be sorted. Stack the biggest one
1165 and process the smallest one on the next iteration. This
1166 minimizes the stack height by insuring that any additional
1167 stack entries must come from the smallest partition which
1168 (because it is smallest) will have the fewest
1169 opportunities to generate additional stack entries.
1171 if ((part_right - pc_right) > (pc_left - part_left)) {
1172 /* stack the right partition, process the left */
1173 partition_stack[next_stack_entry].left = pc_right + 1;
1174 partition_stack[next_stack_entry].right = part_right;
1175 #ifdef QSORT_ORDER_GUESS
1176 partition_stack[next_stack_entry].qsort_break_even = qsort_break_even;
1178 part_right = pc_left - 1;
1180 /* stack the left partition, process the right */
1181 partition_stack[next_stack_entry].left = part_left;
1182 partition_stack[next_stack_entry].right = pc_left - 1;
1183 #ifdef QSORT_ORDER_GUESS
1184 partition_stack[next_stack_entry].qsort_break_even = qsort_break_even;
1186 part_left = pc_right + 1;
1188 qsort_assert(next_stack_entry < QSORT_MAX_STACK);
1191 /* The elements on the left are the only remaining elements
1192 that need sorting, arrange for them to be processed as the
1195 part_right = pc_left - 1;
1197 } else if (pc_right < part_right) {
1198 /* There is only one chunk on the right to be sorted, make it
1199 the new partition and loop back around.
1201 part_left = pc_right + 1;
1203 /* This whole partition wound up in the pivot chunk, so
1204 we need to get a new partition off the stack.
1206 if (next_stack_entry == 0) {
1207 /* the stack is empty - we are done */
1211 part_left = partition_stack[next_stack_entry].left;
1212 part_right = partition_stack[next_stack_entry].right;
1213 #ifdef QSORT_ORDER_GUESS
1214 qsort_break_even = partition_stack[next_stack_entry].qsort_break_even;
1218 /* This partition is too small to fool with qsort complexity, just
1219 do an ordinary insertion sort to minimize overhead.
1222 /* Assume 1st element is in right place already, and start checking
1223 at 2nd element to see where it should be inserted.
1225 for (i = part_left + 1; i <= part_right; ++i) {
1227 /* Scan (backwards - just in case 'i' is already in right place)
1228 through the elements already sorted to see if the ith element
1229 belongs ahead of one of them.
1231 for (j = i - 1; j >= part_left; --j) {
1232 if (qsort_cmp(i, j) >= 0) {
1233 /* i belongs right after j
1240 /* Looks like we really need to move some things
1244 for (k = i - 1; k >= j; --k)
1245 array[k + 1] = array[k];
1250 /* That partition is now sorted, grab the next one, or get out
1251 of the loop if there aren't any more.
1254 if (next_stack_entry == 0) {
1255 /* the stack is empty - we are done */
1259 part_left = partition_stack[next_stack_entry].left;
1260 part_right = partition_stack[next_stack_entry].right;
1261 #ifdef QSORT_ORDER_GUESS
1262 qsort_break_even = partition_stack[next_stack_entry].qsort_break_even;
1267 /* Believe it or not, the array is sorted at this point! */
1270 /* Stabilize what is, presumably, an otherwise unstable sort method.
1271 * We do that by allocating (or having on hand) an array of pointers
1272 * that is the same size as the original array of elements to be sorted.
1273 * We initialize this parallel array with the addresses of the original
1274 * array elements. This indirection can make you crazy.
1275 * Some pictures can help. After initializing, we have
1279 * | | --------------> | | ------> first element to be sorted
1281 * | | --------------> | | ------> second element to be sorted
1283 * | | --------------> | | ------> third element to be sorted
1287 * | | --------------> | | ------> n-1st element to be sorted
1289 * | | --------------> | | ------> n-th element to be sorted
1292 * During the sort phase, we leave the elements of list1 where they are,
1293 * and sort the pointers in the indirect array in the same order determined
1294 * by the original comparison routine on the elements pointed to.
1295 * Because we don't move the elements of list1 around through
1296 * this phase, we can break ties on elements that compare equal
1297 * using their address in the list1 array, ensuring stability.
1298 * This leaves us with something looking like
1302 * | | --+ +---> | | ------> first element to be sorted
1304 * | | --|-------|---> | | ------> second element to be sorted
1306 * | | --|-------+ +-> | | ------> third element to be sorted
1309 * +----+ | | | | +----+
1310 * | | ---|-+ | +--> | | ------> n-1st element to be sorted
1312 * | | ---+ +----> | | ------> n-th element to be sorted
1315 * where the i-th element of the indirect array points to the element
1316 * that should be i-th in the sorted array. After the sort phase,
1317 * we have to put the elements of list1 into the places
1318 * dictated by the indirect array.
1323 cmpindir(pTHX_ gptr const a, gptr const b)
1326 gptr * const ap = (gptr *)a;
1327 gptr * const bp = (gptr *)b;
1328 const I32 sense = PL_sort_RealCmp(aTHX_ *ap, *bp);
1332 return (ap > bp) ? 1 : ((ap < bp) ? -1 : 0);
1336 cmpindir_desc(pTHX_ gptr const a, gptr const b)
1339 gptr * const ap = (gptr *)a;
1340 gptr * const bp = (gptr *)b;
1341 const I32 sense = PL_sort_RealCmp(aTHX_ *ap, *bp);
1343 /* Reverse the default */
1346 /* But don't reverse the stability test. */
1347 return (ap > bp) ? 1 : ((ap < bp) ? -1 : 0);
1352 S_qsortsv(pTHX_ gptr *list1, size_t nmemb, SVCOMPARE_t cmp, U32 flags)
1355 if ((flags & SORTf_STABLE) != 0) {
1358 gptr *small[SMALLSORT], **indir, tmp;
1359 SVCOMPARE_t savecmp;
1360 if (nmemb <= 1) return; /* sorted trivially */
1362 /* Small arrays can use the stack, big ones must be allocated */
1363 if (nmemb <= SMALLSORT) indir = small;
1364 else { Newx(indir, nmemb, gptr *); }
1366 /* Copy pointers to original array elements into indirect array */
1367 for (n = nmemb, pp = indir, q = list1; n--; ) *pp++ = q++;
1369 savecmp = PL_sort_RealCmp; /* Save current comparison routine, if any */
1370 PL_sort_RealCmp = cmp; /* Put comparison routine where cmpindir can find it */
1372 /* sort, with indirection */
1373 if (flags & SORTf_DESC)
1374 qsortsvu((gptr *)indir, nmemb, cmpindir_desc);
1376 qsortsvu((gptr *)indir, nmemb, cmpindir);
1380 for (n = nmemb; n--; ) {
1381 /* Assert A: all elements of q with index > n are already
1382 * in place. This is vacuously true at the start, and we
1383 * put element n where it belongs below (if it wasn't
1384 * already where it belonged). Assert B: we only move
1385 * elements that aren't where they belong,
1386 * so, by A, we never tamper with elements above n.
1388 j = pp[n] - q; /* This sets j so that q[j] is
1389 * at pp[n]. *pp[j] belongs in
1390 * q[j], by construction.
1392 if (n != j) { /* all's well if n == j */
1393 tmp = q[j]; /* save what's in q[j] */
1395 q[j] = *pp[j]; /* put *pp[j] where it belongs */
1396 i = pp[j] - q; /* the index in q of the element
1398 pp[j] = q + j; /* this is ok now */
1399 } while ((j = i) != n);
1400 /* There are only finitely many (nmemb) addresses
1402 * So we must eventually revisit an index we saw before.
1403 * Suppose the first revisited index is k != n.
1404 * An index is visited because something else belongs there.
1405 * If we visit k twice, then two different elements must
1406 * belong in the same place, which cannot be.
1407 * So j must get back to n, the loop terminates,
1408 * and we put the saved element where it belongs.
1410 q[n] = tmp; /* put what belongs into
1411 * the n-th element */
1415 /* free iff allocated */
1416 if (indir != small) { Safefree(indir); }
1417 /* restore prevailing comparison routine */
1418 PL_sort_RealCmp = savecmp;
1419 } else if ((flags & SORTf_DESC) != 0) {
1420 const SVCOMPARE_t savecmp = PL_sort_RealCmp; /* Save current comparison routine, if any */
1421 PL_sort_RealCmp = cmp; /* Put comparison routine where cmp_desc can find it */
1423 qsortsvu(list1, nmemb, cmp);
1424 /* restore prevailing comparison routine */
1425 PL_sort_RealCmp = savecmp;
1427 qsortsvu(list1, nmemb, cmp);
1432 =head1 Array Manipulation Functions
1436 Sort an array. Here is an example:
1438 sortsv(AvARRAY(av), av_top_index(av)+1, Perl_sv_cmp_locale);
1440 Currently this always uses mergesort. See sortsv_flags for a more
1447 Perl_sortsv(pTHX_ SV **array, size_t nmemb, SVCOMPARE_t cmp)
1449 PERL_ARGS_ASSERT_SORTSV;
1451 sortsv_flags(array, nmemb, cmp, 0);
1455 =for apidoc sortsv_flags
1457 Sort an array, with various options.
1462 Perl_sortsv_flags(pTHX_ SV **array, size_t nmemb, SVCOMPARE_t cmp, U32 flags)
1464 PERL_ARGS_ASSERT_SORTSV_FLAGS;
1466 if (flags & SORTf_QSORT)
1467 S_qsortsv(aTHX_ array, nmemb, cmp, flags);
1469 S_mergesortsv(aTHX_ array, nmemb, cmp, flags);
1472 #define SvNSIOK(sv) ((SvFLAGS(sv) & SVf_NOK) || ((SvFLAGS(sv) & (SVf_IOK|SVf_IVisUV)) == SVf_IOK))
1473 #define SvSIOK(sv) ((SvFLAGS(sv) & (SVf_IOK|SVf_IVisUV)) == SVf_IOK)
1474 #define SvNSIV(sv) ( SvNOK(sv) ? SvNVX(sv) : ( SvSIOK(sv) ? SvIVX(sv) : sv_2nv(sv) ) )
1478 dVAR; dSP; dMARK; dORIGMARK;
1479 SV **p1 = ORIGMARK+1, **p2;
1485 OP* const nextop = PL_op->op_next;
1486 I32 overloading = 0;
1487 bool hasargs = FALSE;
1491 const U8 priv = PL_op->op_private;
1492 const U8 flags = PL_op->op_flags;
1494 void (*sortsvp)(pTHX_ SV **array, size_t nmemb, SVCOMPARE_t cmp, U32 flags)
1495 = Perl_sortsv_flags;
1498 if ((priv & OPpSORT_DESCEND) != 0)
1499 sort_flags |= SORTf_DESC;
1500 if ((priv & OPpSORT_QSORT) != 0)
1501 sort_flags |= SORTf_QSORT;
1502 if ((priv & OPpSORT_STABLE) != 0)
1503 sort_flags |= SORTf_STABLE;
1505 if (gimme != G_ARRAY) {
1512 SAVEVPTR(PL_sortcop);
1513 if (flags & OPf_STACKED) {
1514 if (flags & OPf_SPECIAL) {
1515 OP *kid = cLISTOP->op_first->op_sibling; /* pass pushmark */
1516 kid = kUNOP->op_first; /* pass rv2gv */
1517 kid = kUNOP->op_first; /* pass leave */
1518 PL_sortcop = kid->op_next;
1523 cv = sv_2cv(*++MARK, &stash, &gv, GV_ADD);
1525 if (cv && SvPOK(cv)) {
1526 const char * const proto = SvPV_nolen_const(MUTABLE_SV(cv));
1527 if (proto && strEQ(proto, "$$")) {
1531 if (cv && CvISXSUB(cv) && CvXSUB(cv)) {
1534 else if (!(cv && CvROOT(cv))) {
1538 else if (!CvANON(cv) && (gv = CvGV(cv))) {
1539 if (cv != GvCV(gv)) cv = GvCV(gv);
1542 autogv = gv_autoload_pvn(
1543 GvSTASH(gv), GvNAME(gv), GvNAMELEN(gv),
1544 GvNAMEUTF8(gv) ? SVf_UTF8 : 0
1551 SV *tmpstr = sv_newmortal();
1552 gv_efullname3(tmpstr, gv, NULL);
1553 DIE(aTHX_ "Undefined sort subroutine \"%"SVf"\" called",
1558 DIE(aTHX_ "Undefined subroutine in sort");
1563 PL_sortcop = (OP*)cv;
1565 PL_sortcop = CvSTART(cv);
1572 /* optimiser converts "@a = sort @a" to "sort \@a";
1573 * in case of tied @a, pessimise: push (@a) onto stack, then assign
1574 * result back to @a at the end of this function */
1575 if (priv & OPpSORT_INPLACE) {
1576 assert( MARK+1 == SP && *SP && SvTYPE(*SP) == SVt_PVAV);
1577 (void)POPMARK; /* remove mark associated with ex-OP_AASSIGN */
1578 av = MUTABLE_AV((*SP));
1579 max = AvFILL(av) + 1;
1580 if (SvMAGICAL(av)) {
1582 for (i=0; i < max; i++) {
1583 SV **svp = av_fetch(av, i, FALSE);
1584 *SP++ = (svp) ? *svp : NULL;
1587 p1 = p2 = SP - (max-1);
1591 Perl_croak_no_modify();
1595 save_pushptr((void *)av, SAVEt_READONLY_OFF);
1597 p1 = p2 = AvARRAY(av);
1606 /* shuffle stack down, removing optional initial cv (p1!=p2), plus
1607 * any nulls; also stringify or converting to integer or number as
1608 * required any args */
1609 copytmps = !sorting_av && PL_sortcop;
1610 for (i=max; i > 0 ; i--) {
1611 if ((*p1 = *p2++)) { /* Weed out nulls. */
1612 if (copytmps && SvPADTMP(*p1) && !IS_PADGV(*p1))
1613 *p1 = sv_mortalcopy(*p1);
1616 if (priv & OPpSORT_NUMERIC) {
1617 if (priv & OPpSORT_INTEGER) {
1619 (void)sv_2iv_flags(*p1, SV_GMAGIC|SV_SKIP_OVERLOAD);
1623 (void)sv_2nv_flags(*p1, SV_GMAGIC|SV_SKIP_OVERLOAD);
1624 if (all_SIVs && !SvSIOK(*p1))
1630 (void)sv_2pv_flags(*p1, 0,
1631 SV_GMAGIC|SV_CONST_RETURN|SV_SKIP_OVERLOAD);
1642 AvFILLp(av) = max-1;
1649 const bool oldcatch = CATCH_GET;
1655 PUSHSTACKi(PERLSI_SORT);
1656 if (!hasargs && !is_xsub) {
1657 SAVEGENERICSV(PL_firstgv);
1658 SAVEGENERICSV(PL_secondgv);
1659 PL_firstgv = MUTABLE_GV(SvREFCNT_inc(
1660 gv_fetchpvs("a", GV_ADD|GV_NOTQUAL, SVt_PV)
1662 PL_secondgv = MUTABLE_GV(SvREFCNT_inc(
1663 gv_fetchpvs("b", GV_ADD|GV_NOTQUAL, SVt_PV)
1665 SAVESPTR(GvSV(PL_firstgv));
1666 SAVESPTR(GvSV(PL_secondgv));
1669 PUSHBLOCK(cx, CXt_NULL, PL_stack_base);
1670 if (!(flags & OPf_SPECIAL)) {
1671 cx->cx_type = CXt_SUB;
1672 cx->blk_gimme = G_SCALAR;
1673 /* If our comparison routine is already active (CvDEPTH is
1674 * is not 0), then PUSHSUB does not increase the refcount,
1675 * so we have to do it ourselves, because the LEAVESUB fur-
1676 * ther down lowers it. */
1677 if (CvDEPTH(cv)) SvREFCNT_inc_simple_void_NN(cv);
1680 PADLIST * const padlist = CvPADLIST(cv);
1682 if (++CvDEPTH(cv) >= 2) {
1683 PERL_STACK_OVERFLOW_CHECK();
1684 pad_push(padlist, CvDEPTH(cv));
1687 PAD_SET_CUR_NOSAVE(padlist, CvDEPTH(cv));
1690 /* This is mostly copied from pp_entersub */
1691 AV * const av = MUTABLE_AV(PAD_SVl(0));
1693 cx->blk_sub.savearray = GvAV(PL_defgv);
1694 GvAV(PL_defgv) = MUTABLE_AV(SvREFCNT_inc_simple(av));
1695 CX_CURPAD_SAVE(cx->blk_sub);
1696 cx->blk_sub.argarray = av;
1701 cx->cx_type |= CXp_MULTICALL;
1704 sortsvp(aTHX_ start, max,
1705 (is_xsub ? S_sortcv_xsub : hasargs ? S_sortcv_stacked : S_sortcv),
1708 if (!(flags & OPf_SPECIAL)) {
1710 /* Reset cx, in case the context stack has been
1712 cx = &cxstack[cxstack_ix];
1716 POPBLOCK(cx,PL_curpm);
1717 PL_stack_sp = newsp;
1719 CATCH_SET(oldcatch);
1722 MEXTEND(SP, 20); /* Can't afford stack realloc on signal. */
1723 start = sorting_av ? AvARRAY(av) : ORIGMARK+1;
1724 sortsvp(aTHX_ start, max,
1725 (priv & OPpSORT_NUMERIC)
1726 ? ( ( ( priv & OPpSORT_INTEGER) || all_SIVs)
1727 ? ( overloading ? S_amagic_i_ncmp : S_sv_i_ncmp)
1728 : ( overloading ? S_amagic_ncmp : S_sv_ncmp ) )
1729 : ( IN_LOCALE_RUNTIME
1731 ? (SVCOMPARE_t)S_amagic_cmp_locale
1732 : (SVCOMPARE_t)sv_cmp_locale_static)
1733 : ( overloading ? (SVCOMPARE_t)S_amagic_cmp : (SVCOMPARE_t)sv_cmp_static)),
1736 if ((priv & OPpSORT_REVERSE) != 0) {
1737 SV **q = start+max-1;
1739 SV * const tmp = *start;
1747 else if (av && !sorting_av) {
1748 /* simulate pp_aassign of tied AV */
1749 SV** const base = MARK+1;
1750 for (i=0; i < max; i++) {
1751 base[i] = newSVsv(base[i]);
1755 for (i=0; i < max; i++) {
1756 SV * const sv = base[i];
1757 SV ** const didstore = av_store(av, i, sv);
1765 PL_stack_sp = ORIGMARK + (sorting_av ? 0 : max);
1770 S_sortcv(pTHX_ SV *const a, SV *const b)
1773 const I32 oldsaveix = PL_savestack_ix;
1774 const I32 oldscopeix = PL_scopestack_ix;
1777 PMOP * const pm = PL_curpm;
1778 OP * const sortop = PL_op;
1779 COP * const cop = PL_curcop;
1781 PERL_ARGS_ASSERT_SORTCV;
1783 GvSV(PL_firstgv) = a;
1784 GvSV(PL_secondgv) = b;
1785 PL_stack_sp = PL_stack_base;
1790 if (PL_stack_sp != PL_stack_base + 1) {
1791 assert(PL_stack_sp == PL_stack_base);
1792 resultsv = &PL_sv_undef;
1794 else resultsv = *PL_stack_sp;
1795 if (SvNIOK_nog(resultsv)) result = SvIV(resultsv);
1798 SAVEVPTR(PL_curpad);
1800 result = SvIV(resultsv);
1803 while (PL_scopestack_ix > oldscopeix) {
1806 leave_scope(oldsaveix);
1812 S_sortcv_stacked(pTHX_ SV *const a, SV *const b)
1815 const I32 oldsaveix = PL_savestack_ix;
1816 const I32 oldscopeix = PL_scopestack_ix;
1818 AV * const av = GvAV(PL_defgv);
1819 PMOP * const pm = PL_curpm;
1820 OP * const sortop = PL_op;
1821 COP * const cop = PL_curcop;
1824 PERL_ARGS_ASSERT_SORTCV_STACKED;
1831 if (AvMAX(av) < 1) {
1832 SV **ary = AvALLOC(av);
1833 if (AvARRAY(av) != ary) {
1834 AvMAX(av) += AvARRAY(av) - AvALLOC(av);
1837 if (AvMAX(av) < 1) {
1848 PL_stack_sp = PL_stack_base;
1853 pad = PL_curpad; PL_curpad = 0;
1854 if (PL_stack_sp != PL_stack_base + 1) {
1855 assert(PL_stack_sp == PL_stack_base);
1856 result = SvIV(&PL_sv_undef);
1858 else result = SvIV(*PL_stack_sp);
1860 while (PL_scopestack_ix > oldscopeix) {
1863 leave_scope(oldsaveix);
1869 S_sortcv_xsub(pTHX_ SV *const a, SV *const b)
1872 const I32 oldsaveix = PL_savestack_ix;
1873 const I32 oldscopeix = PL_scopestack_ix;
1874 CV * const cv=MUTABLE_CV(PL_sortcop);
1876 PMOP * const pm = PL_curpm;
1878 PERL_ARGS_ASSERT_SORTCV_XSUB;
1886 (void)(*CvXSUB(cv))(aTHX_ cv);
1887 if (PL_stack_sp != PL_stack_base + 1)
1888 Perl_croak(aTHX_ "Sort subroutine didn't return single value");
1889 result = SvIV(*PL_stack_sp);
1890 while (PL_scopestack_ix > oldscopeix) {
1893 leave_scope(oldsaveix);
1900 S_sv_ncmp(pTHX_ SV *const a, SV *const b)
1902 const NV nv1 = SvNSIV(a);
1903 const NV nv2 = SvNSIV(b);
1905 PERL_ARGS_ASSERT_SV_NCMP;
1907 #if defined(NAN_COMPARE_BROKEN) && defined(Perl_isnan)
1908 if (Perl_isnan(nv1) || Perl_isnan(nv2)) {
1910 if (nv1 != nv1 || nv2 != nv2) {
1912 if (ckWARN(WARN_UNINITIALIZED)) report_uninit(NULL);
1915 return nv1 < nv2 ? -1 : nv1 > nv2 ? 1 : 0;
1919 S_sv_i_ncmp(pTHX_ SV *const a, SV *const b)
1921 const IV iv1 = SvIV(a);
1922 const IV iv2 = SvIV(b);
1924 PERL_ARGS_ASSERT_SV_I_NCMP;
1926 return iv1 < iv2 ? -1 : iv1 > iv2 ? 1 : 0;
1929 #define tryCALL_AMAGICbin(left,right,meth) \
1930 (SvAMAGIC(left)||SvAMAGIC(right)) \
1931 ? amagic_call(left, right, meth, 0) \
1934 #define SORT_NORMAL_RETURN_VALUE(val) (((val) > 0) ? 1 : ((val) ? -1 : 0))
1937 S_amagic_ncmp(pTHX_ SV *const a, SV *const b)
1940 SV * const tmpsv = tryCALL_AMAGICbin(a,b,ncmp_amg);
1942 PERL_ARGS_ASSERT_AMAGIC_NCMP;
1946 const I32 i = SvIVX(tmpsv);
1947 return SORT_NORMAL_RETURN_VALUE(i);
1950 const NV d = SvNV(tmpsv);
1951 return SORT_NORMAL_RETURN_VALUE(d);
1954 return S_sv_ncmp(aTHX_ a, b);
1958 S_amagic_i_ncmp(pTHX_ SV *const a, SV *const b)
1961 SV * const tmpsv = tryCALL_AMAGICbin(a,b,ncmp_amg);
1963 PERL_ARGS_ASSERT_AMAGIC_I_NCMP;
1967 const I32 i = SvIVX(tmpsv);
1968 return SORT_NORMAL_RETURN_VALUE(i);
1971 const NV d = SvNV(tmpsv);
1972 return SORT_NORMAL_RETURN_VALUE(d);
1975 return S_sv_i_ncmp(aTHX_ a, b);
1979 S_amagic_cmp(pTHX_ SV *const str1, SV *const str2)
1982 SV * const tmpsv = tryCALL_AMAGICbin(str1,str2,scmp_amg);
1984 PERL_ARGS_ASSERT_AMAGIC_CMP;
1988 const I32 i = SvIVX(tmpsv);
1989 return SORT_NORMAL_RETURN_VALUE(i);
1992 const NV d = SvNV(tmpsv);
1993 return SORT_NORMAL_RETURN_VALUE(d);
1996 return sv_cmp(str1, str2);
2000 S_amagic_cmp_locale(pTHX_ SV *const str1, SV *const str2)
2003 SV * const tmpsv = tryCALL_AMAGICbin(str1,str2,scmp_amg);
2005 PERL_ARGS_ASSERT_AMAGIC_CMP_LOCALE;
2009 const I32 i = SvIVX(tmpsv);
2010 return SORT_NORMAL_RETURN_VALUE(i);
2013 const NV d = SvNV(tmpsv);
2014 return SORT_NORMAL_RETURN_VALUE(d);
2017 return sv_cmp_locale(str1, str2);
2022 * c-indentation-style: bsd
2024 * indent-tabs-mode: nil
2027 * ex: set ts=8 sts=4 sw=4 et: