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[perl5.git] / universal.c
1 /*    universal.c
2  *
3  *    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
4  *    2005, by Larry Wall and others
5  *
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.
8  *
9  */
10
11 /*
12  * "The roots of those mountains must be roots indeed; there must be
13  * great secrets buried there which have not been discovered since the
14  * beginning." --Gandalf, relating Gollum's story
15  */
16
17 /* This file contains the code that implements the functions in Perl's
18  * UNIVERSAL package, such as UNIVERSAL->can().
19  */
20
21 #include "EXTERN.h"
22 #define PERL_IN_UNIVERSAL_C
23 #include "perl.h"
24
25 #ifdef USE_PERLIO
26 #include "perliol.h" /* For the PERLIO_F_XXX */
27 #endif
28
29 /*
30  * Contributed by Graham Barr  <Graham.Barr@tiuk.ti.com>
31  * The main guts of traverse_isa was actually copied from gv_fetchmeth
32  */
33
34 STATIC SV *
35 S_isa_lookup(pTHX_ HV *stash, const char *name, HV* name_stash,
36              int len, int level)
37 {
38     AV* av;
39     GV* gv;
40     GV** gvp;
41     HV* hv = Nullhv;
42     SV* subgen = Nullsv;
43     const char *hvname;
44
45     /* A stash/class can go by many names (ie. User == main::User), so 
46        we compare the stash itself just in case */
47     if (name_stash && (stash == name_stash))
48         return &PL_sv_yes;
49
50     hvname = HvNAME_get(stash);
51
52     if (strEQ(hvname, name))
53         return &PL_sv_yes;
54
55     if (strEQ(name, "UNIVERSAL"))
56         return &PL_sv_yes;
57
58     if (level > 100)
59         Perl_croak(aTHX_ "Recursive inheritance detected in package '%s'",
60                    hvname);
61
62     gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, FALSE);
63
64     if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (subgen = GvSV(gv))
65         && (hv = GvHV(gv)))
66     {
67         if (SvIV(subgen) == (IV)PL_sub_generation) {
68             SV* sv;
69             SV** svp = (SV**)hv_fetch(hv, name, len, FALSE);
70             if (svp && (sv = *svp) != (SV*)&PL_sv_undef) {
71                 DEBUG_o( Perl_deb(aTHX_ "Using cached ISA %s for package %s\n",
72                                   name, hvname) );
73                 return sv;
74             }
75         }
76         else {
77             DEBUG_o( Perl_deb(aTHX_ "ISA Cache in package %s is stale\n",
78                               hvname) );
79             hv_clear(hv);
80             sv_setiv(subgen, PL_sub_generation);
81         }
82     }
83
84     gvp = (GV**)hv_fetch(stash,"ISA",3,FALSE);
85
86     if (gvp && (gv = *gvp) != (GV*)&PL_sv_undef && (av = GvAV(gv))) {
87         if (!hv || !subgen) {
88             gvp = (GV**)hv_fetch(stash, "::ISA::CACHE::", 14, TRUE);
89
90             gv = *gvp;
91
92             if (SvTYPE(gv) != SVt_PVGV)
93                 gv_init(gv, stash, "::ISA::CACHE::", 14, TRUE);
94
95             if (!hv)
96                 hv = GvHVn(gv);
97             if (!subgen) {
98                 subgen = newSViv(PL_sub_generation);
99                 GvSV(gv) = subgen;
100             }
101         }
102         if (hv) {
103             SV** svp = AvARRAY(av);
104             /* NOTE: No support for tied ISA */
105             I32 items = AvFILLp(av) + 1;
106             while (items--) {
107                 SV* sv = *svp++;
108                 HV* basestash = gv_stashsv(sv, FALSE);
109                 if (!basestash) {
110                     if (ckWARN(WARN_MISC))
111                         Perl_warner(aTHX_ packWARN(WARN_SYNTAX),
112                                     "Can't locate package %"SVf" for @%s::ISA",
113                                     sv, hvname);
114                     continue;
115                 }
116                 if (&PL_sv_yes == isa_lookup(basestash, name, name_stash, 
117                                              len, level + 1)) {
118                     (void)hv_store(hv,name,len,&PL_sv_yes,0);
119                     return &PL_sv_yes;
120                 }
121             }
122             (void)hv_store(hv,name,len,&PL_sv_no,0);
123         }
124     }
125     return &PL_sv_no;
126 }
127
128 /*
129 =head1 SV Manipulation Functions
130
131 =for apidoc sv_derived_from
132
133 Returns a boolean indicating whether the SV is derived from the specified
134 class.  This is the function that implements C<UNIVERSAL::isa>.  It works
135 for class names as well as for objects.
136
137 =cut
138 */
139
140 bool
141 Perl_sv_derived_from(pTHX_ SV *sv, const char *name)
142 {
143     const char *type = Nullch;
144     HV *stash = Nullhv;
145     HV *name_stash;
146
147     if (SvGMAGICAL(sv))
148         mg_get(sv) ;
149
150     if (SvROK(sv)) {
151         sv = SvRV(sv);
152         type = sv_reftype(sv,0);
153         if (SvOBJECT(sv))
154             stash = SvSTASH(sv);
155     }
156     else {
157         stash = gv_stashsv(sv, FALSE);
158     }
159
160     name_stash = gv_stashpv(name, FALSE);
161
162     return (type && strEQ(type,name)) ||
163             (stash && isa_lookup(stash, name, name_stash, strlen(name), 0) 
164              == &PL_sv_yes)
165         ? TRUE
166         : FALSE ;
167 }
168
169 #include "XSUB.h"
170
171 PERL_XS_EXPORT_C void XS_UNIVERSAL_isa(pTHX_ CV *cv);
172 PERL_XS_EXPORT_C void XS_UNIVERSAL_can(pTHX_ CV *cv);
173 PERL_XS_EXPORT_C void XS_UNIVERSAL_VERSION(pTHX_ CV *cv);
174 XS(XS_version_new);
175 XS(XS_version_stringify);
176 XS(XS_version_numify);
177 XS(XS_version_normal);
178 XS(XS_version_vcmp);
179 XS(XS_version_boolean);
180 #ifdef HASATTRIBUTE_NORETURN
181 XS(XS_version_noop) __attribute__noreturn__;
182 #else
183 XS(XS_version_noop);
184 #endif
185 XS(XS_version_is_alpha);
186 XS(XS_version_qv);
187 XS(XS_utf8_is_utf8);
188 XS(XS_utf8_valid);
189 XS(XS_utf8_encode);
190 XS(XS_utf8_decode);
191 XS(XS_utf8_upgrade);
192 XS(XS_utf8_downgrade);
193 XS(XS_utf8_unicode_to_native);
194 XS(XS_utf8_native_to_unicode);
195 XS(XS_Internals_SvREADONLY);
196 XS(XS_Internals_SvREFCNT);
197 XS(XS_Internals_hv_clear_placehold);
198 XS(XS_PerlIO_get_layers);
199 XS(XS_Regexp_DESTROY);
200 XS(XS_Internals_hash_seed);
201 XS(XS_Internals_rehash_seed);
202 XS(XS_Internals_HvREHASH);
203
204 void
205 Perl_boot_core_UNIVERSAL(pTHX)
206 {
207     const char file[] = __FILE__;
208
209     newXS("UNIVERSAL::isa",             XS_UNIVERSAL_isa,         file);
210     newXS("UNIVERSAL::can",             XS_UNIVERSAL_can,         file);
211     newXS("UNIVERSAL::VERSION",         XS_UNIVERSAL_VERSION,     file);
212     {
213         /* register the overloading (type 'A') magic */
214         PL_amagic_generation++;
215         /* Make it findable via fetchmethod */
216         newXS("version::()", XS_version_noop, file);
217         newXS("version::new", XS_version_new, file);
218         newXS("version::(\"\"", XS_version_stringify, file);
219         newXS("version::stringify", XS_version_stringify, file);
220         newXS("version::(0+", XS_version_numify, file);
221         newXS("version::numify", XS_version_numify, file);
222         newXS("version::normal", XS_version_normal, file);
223         newXS("version::(cmp", XS_version_vcmp, file);
224         newXS("version::(<=>", XS_version_vcmp, file);
225         newXS("version::vcmp", XS_version_vcmp, file);
226         newXS("version::(bool", XS_version_boolean, file);
227         newXS("version::boolean", XS_version_boolean, file);
228         newXS("version::(nomethod", XS_version_noop, file);
229         newXS("version::noop", XS_version_noop, file);
230         newXS("version::is_alpha", XS_version_is_alpha, file);
231         newXS("version::qv", XS_version_qv, file);
232     }
233     newXS("utf8::is_utf8", XS_utf8_is_utf8, file);
234     newXS("utf8::valid", XS_utf8_valid, file);
235     newXS("utf8::encode", XS_utf8_encode, file);
236     newXS("utf8::decode", XS_utf8_decode, file);
237     newXS("utf8::upgrade", XS_utf8_upgrade, file);
238     newXS("utf8::downgrade", XS_utf8_downgrade, file);
239     newXS("utf8::native_to_unicode", XS_utf8_native_to_unicode, file);
240     newXS("utf8::unicode_to_native", XS_utf8_unicode_to_native, file);
241     newXSproto("Internals::SvREADONLY",XS_Internals_SvREADONLY, file, "\\[$%@];$");
242     newXSproto("Internals::SvREFCNT",XS_Internals_SvREFCNT, file, "\\[$%@];$");
243     newXSproto("Internals::hv_clear_placeholders",
244                XS_Internals_hv_clear_placehold, file, "\\%");
245     newXSproto("PerlIO::get_layers",
246                XS_PerlIO_get_layers, file, "*;@");
247     newXS("Regexp::DESTROY", XS_Regexp_DESTROY, file);
248     newXSproto("Internals::hash_seed",XS_Internals_hash_seed, file, "");
249     newXSproto("Internals::rehash_seed",XS_Internals_rehash_seed, file, "");
250     newXSproto("Internals::HvREHASH", XS_Internals_HvREHASH, file, "\\%");
251 }
252
253
254 XS(XS_UNIVERSAL_isa)
255 {
256     dXSARGS;
257     SV *sv;
258     const char *name;
259
260     if (items != 2)
261         Perl_croak(aTHX_ "Usage: UNIVERSAL::isa(reference, kind)");
262
263     sv = ST(0);
264
265     if (SvGMAGICAL(sv))
266         mg_get(sv);
267
268     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
269                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
270         XSRETURN_UNDEF;
271
272     name = SvPV_nolen_const(ST(1));
273
274     ST(0) = boolSV(sv_derived_from(sv, name));
275     XSRETURN(1);
276 }
277
278 XS(XS_UNIVERSAL_can)
279 {
280     dXSARGS;
281     SV   *sv;
282     const char *name;
283     SV   *rv;
284     HV   *pkg = NULL;
285
286     if (items != 2)
287         Perl_croak(aTHX_ "Usage: UNIVERSAL::can(object-ref, method)");
288
289     sv = ST(0);
290
291     if (SvGMAGICAL(sv))
292         mg_get(sv);
293
294     if (!SvOK(sv) || !(SvROK(sv) || (SvPOK(sv) && SvCUR(sv))
295                 || (SvGMAGICAL(sv) && SvPOKp(sv) && SvCUR(sv))))
296         XSRETURN_UNDEF;
297
298     name = SvPV_nolen_const(ST(1));
299     rv = &PL_sv_undef;
300
301     if (SvROK(sv)) {
302         sv = (SV*)SvRV(sv);
303         if (SvOBJECT(sv))
304             pkg = SvSTASH(sv);
305     }
306     else {
307         pkg = gv_stashsv(sv, FALSE);
308     }
309
310     if (pkg) {
311         GV *gv = gv_fetchmethod_autoload(pkg, name, FALSE);
312         if (gv && isGV(gv))
313             rv = sv_2mortal(newRV((SV*)GvCV(gv)));
314     }
315
316     ST(0) = rv;
317     XSRETURN(1);
318 }
319
320 XS(XS_UNIVERSAL_VERSION)
321 {
322     dXSARGS;
323     HV *pkg;
324     GV **gvp;
325     GV *gv;
326     SV *sv;
327     const char *undef;
328
329     if (SvROK(ST(0))) {
330         sv = (SV*)SvRV(ST(0));
331         if (!SvOBJECT(sv))
332             Perl_croak(aTHX_ "Cannot find version of an unblessed reference");
333         pkg = SvSTASH(sv);
334     }
335     else {
336         pkg = gv_stashsv(ST(0), FALSE);
337     }
338
339     gvp = pkg ? (GV**)hv_fetch(pkg,"VERSION",7,FALSE) : Null(GV**);
340
341     if (gvp && isGV(gv = *gvp) && SvOK(sv = GvSV(gv))) {
342         SV *nsv = sv_newmortal();
343         sv_setsv(nsv, sv);
344         sv = nsv;
345         if ( !sv_derived_from(sv, "version"))
346             upg_version(sv);
347         undef = Nullch;
348     }
349     else {
350         sv = (SV*)&PL_sv_undef;
351         undef = "(undef)";
352     }
353
354     if (items > 1) {
355         SV *req = ST(1);
356
357         if (undef) {
358             if (pkg) {
359                 const char *name = HvNAME_get(pkg);
360                 Perl_croak(aTHX_
361                            "%s does not define $%s::VERSION--version check failed",
362                            name, name);
363             } else {
364                 Perl_croak(aTHX_
365                              "%s defines neither package nor VERSION--version check failed",
366                              SvPVx_nolen_const(ST(0)) );
367              }
368         }
369
370         if ( !sv_derived_from(req, "version")) {
371             /* req may very well be R/O, so create a new object */
372             SV *nsv = sv_newmortal();
373             sv_setsv(nsv, req);
374             req = nsv;
375             upg_version(req);
376         }
377
378         if ( vcmp( req, sv ) > 0 )
379             Perl_croak(aTHX_ "%s version %"SVf" (%"SVf") required--"
380                     "this is only version %"SVf" (%"SVf")", HvNAME_get(pkg),
381                     vnumify(req),vnormal(req),vnumify(sv),vnormal(sv));
382     }
383
384     if ( SvOK(sv) && sv_derived_from(sv, "version") ) {
385         ST(0) = vnumify(sv);
386     } else {
387         ST(0) = sv;
388     }
389
390     XSRETURN(1);
391 }
392
393 XS(XS_version_new)
394 {
395     dXSARGS;
396     if (items > 3)
397         Perl_croak(aTHX_ "Usage: version::new(class, version)");
398     SP -= items;
399     {
400         SV *vs = ST(1);
401         SV *rv;
402         const char *classname;
403
404         /* get the class if called as an object method */
405         if ( sv_isobject(ST(0)) ) {
406             classname = HvNAME(SvSTASH(SvRV(ST(0))));
407         }
408         else {
409             classname = (char *)SvPV_nolen(ST(0));
410         }
411
412         if ( items == 1 ) {
413             /* no parameter provided */
414             if ( sv_isobject(ST(0)) ) {
415                 /* copy existing object */
416                 vs = ST(0);
417             }
418             else {
419                 /* create empty object */
420                 vs = sv_newmortal();
421                 sv_setpvn(vs,"",0);
422             }
423         }
424         else if ( items == 3 ) {
425             vs = sv_newmortal();
426             Perl_sv_setpvf(aTHX_ vs,"v%s",SvPV_nolen_const(ST(2)));
427         }
428
429         rv = new_version(vs);
430         if ( strcmp(classname,"version") != 0 ) /* inherited new() */
431             sv_bless(rv, gv_stashpv(classname,TRUE));
432
433         PUSHs(sv_2mortal(rv));
434         PUTBACK;
435         return;
436     }
437 }
438
439 XS(XS_version_stringify)
440 {
441      dXSARGS;
442      if (items < 1)
443           Perl_croak(aTHX_ "Usage: version::stringify(lobj, ...)");
444      SP -= items;
445      {
446           SV *  lobj = Nullsv;
447
448           if (sv_derived_from(ST(0), "version")) {
449                lobj = SvRV(ST(0));
450           }
451           else
452                Perl_croak(aTHX_ "lobj is not of type version");
453
454           PUSHs(sv_2mortal(vstringify(lobj)));
455
456           PUTBACK;
457           return;
458      }
459 }
460
461 XS(XS_version_numify)
462 {
463      dXSARGS;
464      if (items < 1)
465           Perl_croak(aTHX_ "Usage: version::numify(lobj, ...)");
466      SP -= items;
467      {
468           SV *  lobj = Nullsv;
469
470           if (sv_derived_from(ST(0), "version")) {
471                lobj = SvRV(ST(0));
472           }
473           else
474                Perl_croak(aTHX_ "lobj is not of type version");
475
476           PUSHs(sv_2mortal(vnumify(lobj)));
477
478           PUTBACK;
479           return;
480      }
481 }
482
483 XS(XS_version_normal)
484 {
485      dXSARGS;
486      if (items < 1)
487           Perl_croak(aTHX_ "Usage: version::normal(lobj, ...)");
488      SP -= items;
489      {
490           SV *  lobj = Nullsv;
491
492           if (sv_derived_from(ST(0), "version")) {
493                lobj = SvRV(ST(0));
494           }
495           else
496                Perl_croak(aTHX_ "lobj is not of type version");
497
498           PUSHs(sv_2mortal(vnormal(lobj)));
499
500           PUTBACK;
501           return;
502      }
503 }
504
505 XS(XS_version_vcmp)
506 {
507      dXSARGS;
508      if (items < 1)
509           Perl_croak(aTHX_ "Usage: version::vcmp(lobj, ...)");
510      SP -= items;
511      {
512           SV *  lobj = Nullsv;
513
514           if (sv_derived_from(ST(0), "version")) {
515                lobj = SvRV(ST(0));
516           }
517           else
518                Perl_croak(aTHX_ "lobj is not of type version");
519
520           {
521                SV       *rs;
522                SV       *rvs;
523                SV * robj = ST(1);
524                IV        swap = (IV)SvIV(ST(2));
525
526                if ( ! sv_derived_from(robj, "version") )
527                {
528                     robj = new_version(robj);
529                }
530                rvs = SvRV(robj);
531
532                if ( swap )
533                {
534                     rs = newSViv(vcmp(rvs,lobj));
535                }
536                else
537                {
538                     rs = newSViv(vcmp(lobj,rvs));
539                }
540
541                PUSHs(sv_2mortal(rs));
542           }
543
544           PUTBACK;
545           return;
546      }
547 }
548
549 XS(XS_version_boolean)
550 {
551      dXSARGS;
552      if (items < 1)
553           Perl_croak(aTHX_ "Usage: version::boolean(lobj, ...)");
554      SP -= items;
555      {
556           SV *  lobj = Nullsv;
557
558           if (sv_derived_from(ST(0), "version")) {
559                lobj = SvRV(ST(0));
560           }
561           else
562                Perl_croak(aTHX_ "lobj is not of type version");
563
564           {
565                SV       *rs;
566                rs = newSViv( vcmp(lobj,new_version(newSVpvn("0",1))) );
567                PUSHs(sv_2mortal(rs));
568           }
569
570           PUTBACK;
571           return;
572      }
573 }
574
575 XS(XS_version_noop)
576 {
577     dXSARGS;
578     if (items < 1)
579         Perl_croak(aTHX_ "Usage: version::noop(lobj, ...)");
580     if (sv_derived_from(ST(0), "version"))
581         Perl_croak(aTHX_ "operation not supported with version object");
582     else
583         Perl_croak(aTHX_ "lobj is not of type version");
584 #ifndef HASATTRIBUTE_NORETURN
585     XSRETURN_EMPTY;
586 #endif
587 }
588
589 XS(XS_version_is_alpha)
590 {
591     dXSARGS;
592     if (items != 1)
593         Perl_croak(aTHX_ "Usage: version::is_alpha(lobj)");
594     SP -= items;
595     {
596         SV * lobj = Nullsv;
597
598         if (sv_derived_from(ST(0), "version"))
599                 lobj = ST(0);
600         else
601                 Perl_croak(aTHX_ "lobj is not of type version");
602 {
603     if ( hv_exists((HV*)SvRV(lobj), "alpha", 5 ) )
604         XSRETURN_YES;
605     else
606         XSRETURN_NO;
607 }
608         PUTBACK;
609         return;
610     }
611 }
612
613 XS(XS_version_qv)
614 {
615     dXSARGS;
616     if (items != 1)
617         Perl_croak(aTHX_ "Usage: version::qv(ver)");
618     SP -= items;
619     {
620         SV *    ver = ST(0);
621         if ( !SvVOK(ver) ) /* only need to do with if not already v-string */
622         {
623             SV *vs = sv_newmortal();
624             char *version;
625             if ( SvNOK(ver) ) /* may get too much accuracy */
626             {
627                 char tbuf[64];
628                 sprintf(tbuf,"%.9"NVgf, SvNVX(ver));
629                 version = savepv(tbuf);
630             }
631             else
632             {
633                 version = savesvpv(ver);
634             }
635             (void)scan_version(version,vs,TRUE);
636             Safefree(version);
637
638             PUSHs(vs);
639         }
640         else
641         {
642             PUSHs(sv_2mortal(new_version(ver)));
643         }
644
645         PUTBACK;
646         return;
647     }
648 }
649
650 XS(XS_utf8_is_utf8)
651 {
652      dXSARGS;
653      if (items != 1)
654           Perl_croak(aTHX_ "Usage: utf8::is_utf8(sv)");
655      {
656           const SV *sv = ST(0);
657           {
658                if (SvUTF8(sv))
659                     XSRETURN_YES;
660                else
661                     XSRETURN_NO;
662           }
663      }
664      XSRETURN_EMPTY;
665 }
666
667 XS(XS_utf8_valid)
668 {
669      dXSARGS;
670      if (items != 1)
671           Perl_croak(aTHX_ "Usage: utf8::valid(sv)");
672      {
673           SV *  sv = ST(0);
674           {
675                STRLEN len;
676                const char *s = SvPV_const(sv,len);
677                if (!SvUTF8(sv) || is_utf8_string((const U8*)s,len))
678                     XSRETURN_YES;
679                else
680                     XSRETURN_NO;
681           }
682      }
683      XSRETURN_EMPTY;
684 }
685
686 XS(XS_utf8_encode)
687 {
688     dXSARGS;
689     if (items != 1)
690         Perl_croak(aTHX_ "Usage: utf8::encode(sv)");
691     {
692         SV *    sv = ST(0);
693
694         sv_utf8_encode(sv);
695     }
696     XSRETURN_EMPTY;
697 }
698
699 XS(XS_utf8_decode)
700 {
701     dXSARGS;
702     if (items != 1)
703         Perl_croak(aTHX_ "Usage: utf8::decode(sv)");
704     {
705         SV *    sv = ST(0);
706         const bool RETVAL = sv_utf8_decode(sv);
707         ST(0) = boolSV(RETVAL);
708         sv_2mortal(ST(0));
709     }
710     XSRETURN(1);
711 }
712
713 XS(XS_utf8_upgrade)
714 {
715     dXSARGS;
716     if (items != 1)
717         Perl_croak(aTHX_ "Usage: utf8::upgrade(sv)");
718     {
719         SV *    sv = ST(0);
720         STRLEN  RETVAL;
721         dXSTARG;
722
723         RETVAL = sv_utf8_upgrade(sv);
724         XSprePUSH; PUSHi((IV)RETVAL);
725     }
726     XSRETURN(1);
727 }
728
729 XS(XS_utf8_downgrade)
730 {
731     dXSARGS;
732     if (items < 1 || items > 2)
733         Perl_croak(aTHX_ "Usage: utf8::downgrade(sv, failok=0)");
734     {
735         SV *    sv = ST(0);
736         const bool failok = (items < 2) ? 0 : (int)SvIV(ST(1));
737         const bool RETVAL = sv_utf8_downgrade(sv, failok);
738
739         ST(0) = boolSV(RETVAL);
740         sv_2mortal(ST(0));
741     }
742     XSRETURN(1);
743 }
744
745 XS(XS_utf8_native_to_unicode)
746 {
747  dXSARGS;
748  const UV uv = SvUV(ST(0));
749
750  if (items > 1)
751      Perl_croak(aTHX_ "Usage: utf8::native_to_unicode(sv)");
752
753  ST(0) = sv_2mortal(newSViv(NATIVE_TO_UNI(uv)));
754  XSRETURN(1);
755 }
756
757 XS(XS_utf8_unicode_to_native)
758 {
759  dXSARGS;
760  const UV uv = SvUV(ST(0));
761
762  if (items > 1)
763      Perl_croak(aTHX_ "Usage: utf8::unicode_to_native(sv)");
764
765  ST(0) = sv_2mortal(newSViv(UNI_TO_NATIVE(uv)));
766  XSRETURN(1);
767 }
768
769 XS(XS_Internals_SvREADONLY)     /* This is dangerous stuff. */
770 {
771     dXSARGS;
772     SV *sv = SvRV(ST(0));
773
774     if (items == 1) {
775          if (SvREADONLY(sv))
776              XSRETURN_YES;
777          else
778              XSRETURN_NO;
779     }
780     else if (items == 2) {
781         if (SvTRUE(ST(1))) {
782             SvREADONLY_on(sv);
783             XSRETURN_YES;
784         }
785         else {
786             /* I hope you really know what you are doing. */
787             SvREADONLY_off(sv);
788             XSRETURN_NO;
789         }
790     }
791     XSRETURN_UNDEF; /* Can't happen. */
792 }
793
794 XS(XS_Internals_SvREFCNT)       /* This is dangerous stuff. */
795 {
796     dXSARGS;
797     SV *sv = SvRV(ST(0));
798
799     if (items == 1)
800          XSRETURN_IV(SvREFCNT(sv) - 1); /* Minus the ref created for us. */
801     else if (items == 2) {
802          /* I hope you really know what you are doing. */
803          SvREFCNT(sv) = SvIV(ST(1));
804          XSRETURN_IV(SvREFCNT(sv));
805     }
806     XSRETURN_UNDEF; /* Can't happen. */
807 }
808
809 XS(XS_Internals_hv_clear_placehold)
810 {
811     dXSARGS;
812     HV *hv = (HV *) SvRV(ST(0));
813
814     if (items != 1)
815         Perl_croak(aTHX_ "Usage: UNIVERSAL::hv_clear_placeholders(hv)");
816     hv_clear_placeholders(hv);
817     XSRETURN(0);
818 }
819
820 XS(XS_Regexp_DESTROY)
821 {
822     PERL_UNUSED_ARG(cv);
823 }
824
825 XS(XS_PerlIO_get_layers)
826 {
827     dXSARGS;
828     if (items < 1 || items % 2 == 0)
829         Perl_croak(aTHX_ "Usage: PerlIO_get_layers(filehandle[,args])");
830 #ifdef USE_PERLIO
831     {
832         SV *    sv;
833         GV *    gv;
834         IO *    io;
835         bool    input = TRUE;
836         bool    details = FALSE;
837
838         if (items > 1) {
839              SV **svp;
840              
841              for (svp = MARK + 2; svp <= SP; svp += 2) {
842                   SV **varp = svp;
843                   SV **valp = svp + 1;
844                   STRLEN klen;
845                   const char *key = SvPV_const(*varp, klen);
846
847                   switch (*key) {
848                   case 'i':
849                        if (klen == 5 && memEQ(key, "input", 5)) {
850                             input = SvTRUE(*valp);
851                             break;
852                        }
853                        goto fail;
854                   case 'o': 
855                        if (klen == 6 && memEQ(key, "output", 6)) {
856                             input = !SvTRUE(*valp);
857                             break;
858                        }
859                        goto fail;
860                   case 'd':
861                        if (klen == 7 && memEQ(key, "details", 7)) {
862                             details = SvTRUE(*valp);
863                             break;
864                        }
865                        goto fail;
866                   default:
867                   fail:
868                        Perl_croak(aTHX_
869                                   "get_layers: unknown argument '%s'",
870                                   key);
871                   }
872              }
873
874              SP -= (items - 1);
875         }
876
877         sv = POPs;
878         gv = (GV*)sv;
879
880         if (!isGV(sv)) {
881              if (SvROK(sv) && isGV(SvRV(sv)))
882                   gv = (GV*)SvRV(sv);
883              else
884                   gv = gv_fetchsv(sv, FALSE, SVt_PVIO);
885         }
886
887         if (gv && (io = GvIO(gv))) {
888              dTARGET;
889              AV* av = PerlIO_get_layers(aTHX_ input ?
890                                         IoIFP(io) : IoOFP(io));
891              I32 i;
892              I32 last = av_len(av);
893              I32 nitem = 0;
894              
895              for (i = last; i >= 0; i -= 3) {
896                   SV **namsvp;
897                   SV **argsvp;
898                   SV **flgsvp;
899                   bool namok, argok, flgok;
900
901                   namsvp = av_fetch(av, i - 2, FALSE);
902                   argsvp = av_fetch(av, i - 1, FALSE);
903                   flgsvp = av_fetch(av, i,     FALSE);
904
905                   namok = namsvp && *namsvp && SvPOK(*namsvp);
906                   argok = argsvp && *argsvp && SvPOK(*argsvp);
907                   flgok = flgsvp && *flgsvp && SvIOK(*flgsvp);
908
909                   if (details) {
910                        XPUSHs(namok
911                               ? newSVpvn(SvPVX_const(*namsvp), SvCUR(*namsvp))
912                               : &PL_sv_undef);
913                        XPUSHs(argok
914                               ? newSVpvn(SvPVX_const(*argsvp), SvCUR(*argsvp))
915                               : &PL_sv_undef);
916                        if (flgok)
917                             XPUSHi(SvIVX(*flgsvp));
918                        else
919                             XPUSHs(&PL_sv_undef);
920                        nitem += 3;
921                   }
922                   else {
923                        if (namok && argok)
924                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf"(%"SVf")",
925                                                *namsvp, *argsvp));
926                        else if (namok)
927                             XPUSHs(Perl_newSVpvf(aTHX_ "%"SVf, *namsvp));
928                        else
929                             XPUSHs(&PL_sv_undef);
930                        nitem++;
931                        if (flgok) {
932                             IV flags = SvIVX(*flgsvp);
933
934                             if (flags & PERLIO_F_UTF8) {
935                                  XPUSHs(newSVpvn("utf8", 4));
936                                  nitem++;
937                             }
938                        }
939                   }
940              }
941
942              SvREFCNT_dec(av);
943
944              XSRETURN(nitem);
945         }
946     }
947 #endif
948
949     XSRETURN(0);
950 }
951
952 XS(XS_Internals_hash_seed)
953 {
954     /* Using dXSARGS would also have dITEM and dSP,
955      * which define 2 unused local variables.  */
956     dAXMARK;
957     PERL_UNUSED_ARG(cv);
958     PERL_UNUSED_VAR(mark);
959     XSRETURN_UV(PERL_HASH_SEED);
960 }
961
962 XS(XS_Internals_rehash_seed)
963 {
964     /* Using dXSARGS would also have dITEM and dSP,
965      * which define 2 unused local variables.  */
966     dAXMARK;
967     PERL_UNUSED_ARG(cv);
968     PERL_UNUSED_VAR(mark);
969     XSRETURN_UV(PL_rehash_seed);
970 }
971
972 XS(XS_Internals_HvREHASH)       /* Subject to change  */
973 {
974     dXSARGS;
975     if (SvROK(ST(0))) {
976         const HV *hv = (HV *) SvRV(ST(0));
977         if (items == 1 && SvTYPE(hv) == SVt_PVHV) {
978             if (HvREHASH(hv))
979                 XSRETURN_YES;
980             else
981                 XSRETURN_NO;
982         }
983     }
984     Perl_croak(aTHX_ "Internals::HvREHASH $hashref");
985 }
986
987 /*
988  * Local variables:
989  * c-indentation-style: bsd
990  * c-basic-offset: 4
991  * indent-tabs-mode: t
992  * End:
993  *
994  * ex: set ts=8 sts=4 sw=4 noet:
995  */