+/*
+=for apidoc av_delete
+
+Deletes the element indexed by C<key> from the array. Returns the
+deleted element. C<flags> is currently ignored.
+
+=cut
+*/
+SV *
+Perl_av_delete(pTHX_ AV *av, I32 key, I32 flags)
+{
+ SV *sv;
+
+ if (!av)
+ return Nullsv;
+ if (SvREADONLY(av))
+ Perl_croak(aTHX_ PL_no_modify);
+ if (key < 0) {
+ key += AvFILL(av) + 1;
+ if (key < 0)
+ return Nullsv;
+ }
+ if (SvRMAGICAL(av)) {
+ SV **svp;
+ if ((mg_find((SV*)av, PERL_MAGIC_tied) ||
+ mg_find((SV*)av, PERL_MAGIC_regdata))
+ && (svp = av_fetch(av, key, TRUE)))
+ {
+ sv = *svp;
+ mg_clear(sv);
+ if (mg_find(sv, PERL_MAGIC_tiedelem)) {
+ sv_unmagic(sv, PERL_MAGIC_tiedelem); /* No longer an element */
+ return sv;
+ }
+ return Nullsv; /* element cannot be deleted */
+ }
+ }
+ if (key > AvFILLp(av))
+ return Nullsv;
+ else {
+ sv = AvARRAY(av)[key];
+ if (key == AvFILLp(av)) {
+ AvARRAY(av)[key] = &PL_sv_undef;
+ do {
+ AvFILLp(av)--;
+ } while (--key >= 0 && AvARRAY(av)[key] == &PL_sv_undef);
+ }
+ else
+ AvARRAY(av)[key] = &PL_sv_undef;
+ if (SvSMAGICAL(av))
+ mg_set((SV*)av);
+ }
+ if (flags & G_DISCARD) {
+ SvREFCNT_dec(sv);
+ sv = Nullsv;
+ }
+ return sv;
+}
+
+/*
+=for apidoc av_exists
+
+Returns true if the element indexed by C<key> has been initialized.
+
+This relies on the fact that uninitialized array elements are set to
+C<&PL_sv_undef>.
+
+=cut
+*/
+bool
+Perl_av_exists(pTHX_ AV *av, I32 key)
+{
+ if (!av)
+ return FALSE;
+ if (key < 0) {
+ key += AvFILL(av) + 1;
+ if (key < 0)
+ return FALSE;
+ }
+ if (SvRMAGICAL(av)) {
+ if (mg_find((SV*)av, PERL_MAGIC_tied) ||
+ mg_find((SV*)av, PERL_MAGIC_regdata))
+ {
+ SV *sv = sv_newmortal();
+ MAGIC *mg;
+
+ mg_copy((SV*)av, sv, 0, key);
+ mg = mg_find(sv, PERL_MAGIC_tiedelem);
+ if (mg) {
+ magic_existspack(sv, mg);
+ return SvTRUE(sv);
+ }
+ }
+ }
+ if (key <= AvFILLp(av) && AvARRAY(av)[key] != &PL_sv_undef
+ && AvARRAY(av)[key])
+ {
+ return TRUE;
+ }
+ else
+ return FALSE;
+}