[gitmo/Class-MOP.git] / mop.c

#include "mop.h"

void
mop_call_xs (pTHX_ XSPROTO(subaddr), CV *cv, SV **mark)
{
    dSP;
    PUSHMARK(mark);
    (*subaddr)(aTHX_ cv);
    PUTBACK;
}

#if PERL_BCDVERSION >= 0x5010000
UV
mop_check_package_cache_flag (pTHX_ HV *stash)
{
    assert(SvTYPE(stash) == SVt_PVHV);

    /* here we're trying to implement a c version of mro::get_pkg_gen($stash),
     * however the perl core doesn't make it easy for us. It doesn't provide an
     * api that just does what we want.
     *
     * However, we know that the information we want is, inside the core,
     * available using HvMROMETA(stash)->pkg_gen. Unfortunately, although the
     * HvMROMETA macro is public, it is implemented using Perl_mro_meta_init,
     * which is not public and only available inside the core, as the mro
     * interface as well as the structure returned by mro_meta_init isn't
     * considered to be stable yet.
     *
     * Perl_mro_meta_init isn't declared static, so we could just define it
     * ourselfs if perls headers don't do that for us, except that won't work
     * on platforms where symbols need to be explicitly exported when linking
     * shared libraries.
     *
     * So our, hopefully temporary, solution is to be even more evil and
     * basically reimplement HvMROMETA in a very fragile way that'll blow up
     * when the relevant parts of the mro implementation in core change.
     *
     * :-(
     *
     */

    return HvAUX(stash)->xhv_mro_meta
         ? HvAUX(stash)->xhv_mro_meta->pkg_gen
         : 0;
}

#else /* pre 5.10.0 */

UV
mop_check_package_cache_flag (pTHX_ HV *stash)
{
    PERL_UNUSED_ARG(stash);
    assert(SvTYPE(stash) == SVt_PVHV);

    return PL_sub_generation;
}
#endif

SV *
mop_call0 (pTHX_ SV *const self, SV *const method)
{
    dSP;
    SV *ret;

    PUSHMARK(SP);
    XPUSHs(self);
    PUTBACK;

    call_sv(method, G_SCALAR | G_METHOD);

    SPAGAIN;
    ret = POPs;
    PUTBACK;

    return ret;
}

int
mop_get_code_info (SV *coderef, char **pkg, char **name)
{
    if (!SvOK(coderef) || !SvROK(coderef) || SvTYPE(SvRV(coderef)) != SVt_PVCV) {
        return 0;
    }

    coderef = SvRV(coderef);

    /* sub is still being compiled */
    if (!CvGV(coderef)) {
        return 0;
    }

    /* I think this only gets triggered with a mangled coderef, but if
       we hit it without the guard, we segfault. The slightly odd return
       value strikes me as an improvement (mst)
    */

    if ( isGV_with_GP(CvGV(coderef)) ) {
        GV *gv   = CvGV(coderef);
        *pkg     = HvNAME( GvSTASH(gv) ? GvSTASH(gv) : CvSTASH(coderef) );
        *name    = GvNAME( CvGV(coderef) );
    } else {
        *pkg     = "__UNKNOWN__";
        *name    = "__ANON__";
    }

    return 1;
}

void
mop_get_package_symbols (HV *stash, type_filter_t filter, get_package_symbols_cb_t cb, void *ud)
{
    HE *he;

    (void)hv_iterinit(stash);

    if (filter == TYPE_FILTER_NONE) {
        while ( (he = hv_iternext(stash)) ) {
            STRLEN keylen;
            const char *key = HePV(he, keylen);
            if (!cb(key, keylen, HeVAL(he), ud)) {
                return;
            }
        }
        return;
    }

    while ( (he = hv_iternext(stash)) ) {
        SV *const gv = HeVAL(he);
        SV *sv = NULL;
        char *key;
        STRLEN keylen;
        char *package;

        switch( SvTYPE(gv) ) {
#ifndef SVt_RV
            case SVt_RV:
#endif
            case SVt_PV:
            case SVt_IV:
                /* expand the gv into a real typeglob if it
                 * contains stub functions and we were asked to
                 * return CODE symbols */
                if (filter == TYPE_FILTER_CODE) {
                    if (SvROK(gv)) {
                        SV* fq;
                        /* we don't really care about the length,
                           but that's the API */
                        key = HePV(he, keylen);
                        package = HvNAME(stash);
                        fq = sv_2mortal(newSVpvf("%s::%s", package, key));
                        sv = (SV *)get_cv(SvPV_nolen(fq), 0);
                        break;
                    }

                    key = HePV(he, keylen);
                    gv_init((GV *)gv, stash, key, keylen, GV_ADDMULTI);
                }
                /* fall through */
            case SVt_PVGV:
                switch (filter) {
                    case TYPE_FILTER_CODE:   sv = (SV *)GvCVu(gv); break;
                    case TYPE_FILTER_ARRAY:  sv = (SV *)GvAV(gv);  break;
                    case TYPE_FILTER_IO:     sv = (SV *)GvIO(gv);  break;
                    case TYPE_FILTER_HASH:   sv = (SV *)GvHV(gv);  break;
                    case TYPE_FILTER_SCALAR: sv = (SV *)GvSV(gv);  break;
                    default:
                        croak("Unknown type");
                }
                break;
            default:
                continue;
        }

        if (sv) {
            const char *key = HePV(he, keylen);
            if (!cb(key, keylen, sv, ud)) {
                return;
            }
        }
    }
}

static bool
collect_all_symbols (const char *key, STRLEN keylen, SV *val, void *ud)
{
    HV *hash = (HV *)ud;

    if (!hv_store (hash, key, keylen, newRV_inc(val), 0)) {
        croak("failed to store symbol ref");
    }

    return TRUE;
}

HV *
mop_get_all_package_symbols (HV *stash, type_filter_t filter)
{
    HV *ret = newHV ();
    mop_get_package_symbols (stash, filter, collect_all_symbols, ret);
    return ret;
}

static MGVTBL mop_accessor_vtbl; /* the MAGIC identity */

CV*
mop_install_simple_accessor(pTHX_ const char* const fq_name, const char* const key, I32 const keylen, XSPROTO(accessor_impl)){
    CV* const xsub  = newXS((char*)fq_name, accessor_impl, __FILE__);
    SV* const keysv = newSVpvn_share(key, keylen, 0U);

    sv_magicext((SV*)xsub, keysv, PERL_MAGIC_ext, &mop_accessor_vtbl, NULL, 0);
    SvREFCNT_dec(keysv); /* sv_magicext() increases refcnt in mg_obj */
    return xsub;
}

static MAGIC*
mop_mg_find_by_vtbl(pTHX_ SV* const sv, const MGVTBL* const vtbl){
    MAGIC* mg;

    assert(sv != NULL);
    for(mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic){
        if(mg->mg_virtual == vtbl){
            break;
        }
    }
    return mg;
}

static SV*
mop_fetch_attr(pTHX_ SV* const self, SV* const key, I32 const create, CV* const cv){
    HE* he;
    if (!SvROK(self)) {
        croak("can't call %s as a class method", GvNAME(CvGV(cv)));
    }
    if (SvTYPE(SvRV(self)) != SVt_PVHV) {
        croak("object is not a hashref");
    }
    if((he = hv_fetch_ent((HV*)SvRV(self), key, create, 0U))){
        return HeVAL(he);
    }
    return NULL;
}
static SV*
mop_delete_attr(pTHX_ SV* const self, SV* const key, CV* const cv){
    SV* sv;
    if (!SvROK(self)) {
        croak("can't call %s as a class method", GvNAME(CvGV(cv)));
    }
    if (SvTYPE(SvRV(self)) != SVt_PVHV) {
        croak("object is not a hashref");
    }
    if((sv = hv_delete_ent((HV*)SvRV(self), key, 0, 0U))){
        return sv;
    }
    return NULL;
}

XS(mop_xs_simple_accessor)
{
    dVAR; dXSARGS;
    MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
    SV* const key   = mg->mg_obj;
    SV* attr;
    if(items == 1){ /* reader */
        attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
    }
    else if (items == 2){ /* writer */
        attr = mop_fetch_attr(aTHX_ ST(0), key, TRUE, cv);
        sv_setsv(attr, ST(1));
    }
    else{
        croak("expected exactly one or two argument");
    }
    ST(0) = attr ? attr : &PL_sv_undef;
    XSRETURN(1);
}


XS(mop_xs_simple_reader)
{
    dVAR; dXSARGS;
    MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
    SV* const key   = mg->mg_obj;
    SV* attr;

    if (items != 1) {
        croak("expected exactly one argument");
    }

    attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
    ST(0) = attr ? attr : &PL_sv_undef;
    XSRETURN(1);
}

XS(mop_xs_simple_writer)
{
    dVAR; dXSARGS;
    MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
    SV* const key   = mg->mg_obj;
    SV* attr;

    if (items != 2) {
        croak("expected exactly two argument");
    }

    attr = mop_fetch_attr(aTHX_ ST(0), key, TRUE, cv);
    sv_setsv(attr, ST(1));
    ST(0) = attr;
    XSRETURN(1);
}

XS(mop_xs_simple_clearer)
{
    dVAR; dXSARGS;
    MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
    SV* const key   = mg->mg_obj;
    SV* attr;

    if (items != 1) {
        croak("expected exactly one argument");
    }

    attr = mop_delete_attr(aTHX_ ST(0), key, cv);
    ST(0) = attr ? attr : &PL_sv_undef;
    XSRETURN(1);
}


XS(mop_xs_simple_predicate)
{
    dVAR; dXSARGS;
    MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
    SV* const key   = mg->mg_obj;
    SV* attr;

    if (items != 1) {
        croak("expected exactly one argument");
    }

    attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
    ST(0) = boolSV(attr); /* exists */
    XSRETURN(1);
}


XS(mop_xs_simple_predicate_for_metaclass)
{
    dVAR; dXSARGS;
    MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
    SV* const key   = mg->mg_obj;
    SV* attr;

    if (items != 1) {
        croak("expected exactly one argument");
    }

    attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
    ST(0) = boolSV(attr && SvOK(attr)); /* defined */
    XSRETURN(1);
}
Commit	Line	Data
d846ade3	1	#include "mop.h"
	2
	3	void
1be56175	4	mop_call_xs (pTHX_ XSPROTO(subaddr), CV cv, SV *mark)
d846ade3	5	{
e3dcef7f	6	dSP;
	7	PUSHMARK(mark);
	8	(*subaddr)(aTHX_ cv);
	9	PUTBACK;
d846ade3	10	}
d846ade3	11
8a2e4cdb	12	#if PERL_BCDVERSION >= 0x5010000
d846ade3	13	UV
	14	mop_check_package_cache_flag (pTHX_ HV *stash)
	15	{
	16	assert(SvTYPE(stash) == SVt_PVHV);
	17
	18	/* here we're trying to implement a c version of mro::get_pkg_gen($stash),
	19	* however the perl core doesn't make it easy for us. It doesn't provide an
	20	* api that just does what we want.
	21	*
	22	* However, we know that the information we want is, inside the core,
	23	* available using HvMROMETA(stash)->pkg_gen. Unfortunately, although the
	24	* HvMROMETA macro is public, it is implemented using Perl_mro_meta_init,
	25	* which is not public and only available inside the core, as the mro
	26	* interface as well as the structure returned by mro_meta_init isn't
	27	* considered to be stable yet.
	28	*
	29	* Perl_mro_meta_init isn't declared static, so we could just define it
	30	* ourselfs if perls headers don't do that for us, except that won't work
	31	* on platforms where symbols need to be explicitly exported when linking
	32	* shared libraries.
	33	*
	34	* So our, hopefully temporary, solution is to be even more evil and
	35	* basically reimplement HvMROMETA in a very fragile way that'll blow up
	36	* when the relevant parts of the mro implementation in core change.
	37	*
	38	* :-(
	39	*
	40	*/
	41
	42	return HvAUX(stash)->xhv_mro_meta
	43	? HvAUX(stash)->xhv_mro_meta->pkg_gen
	44	: 0;
	45	}
	46
	47	#else /* pre 5.10.0 */
	48
	49	UV
	50	mop_check_package_cache_flag (pTHX_ HV *stash)
	51	{
	52	PERL_UNUSED_ARG(stash);
	53	assert(SvTYPE(stash) == SVt_PVHV);
	54
	55	return PL_sub_generation;
	56	}
	57	#endif
	58
	59	SV *
	60	mop_call0 (pTHX_ SV const self, SV const method)
	61	{
	62	dSP;
	63	SV *ret;
	64
	65	PUSHMARK(SP);
	66	XPUSHs(self);
	67	PUTBACK;
	68
	69	call_sv(method, G_SCALAR \| G_METHOD);
	70
	71	SPAGAIN;
	72	ret = POPs;
	73	PUTBACK;
	74
	75	return ret;
	76	}
77
78	int
e1f52a8a	79	mop_get_code_info (SV coderef, char pkg, char *name)
d846ade3	80	{
	81	if (!SvOK(coderef) \|\| !SvROK(coderef) \|\| SvTYPE(SvRV(coderef)) != SVt_PVCV) {
	82	return 0;
	83	}
	84
	85	coderef = SvRV(coderef);
caa6b5cd	86
	87	/* sub is still being compiled */
	88	if (!CvGV(coderef)) {
	89	return 0;
	90	}
	91
d846ade3	92	/* I think this only gets triggered with a mangled coderef, but if
	93	we hit it without the guard, we segfault. The slightly odd return
	94	value strikes me as an improvement (mst)
	95	*/
9b52bbf1	96
d846ade3	97	if ( isGV_with_GP(CvGV(coderef)) ) {
2087a201	98	GV *gv = CvGV(coderef);
2087a201	99	*pkg = HvNAME( GvSTASH(gv) ? GvSTASH(gv) : CvSTASH(coderef) );
d846ade3	100	*name = GvNAME( CvGV(coderef) );
d846ade3	101	} else {
	102	*pkg = "__UNKNOWN__";
	103	*name = "__ANON__";
	104	}
d846ade3	105
	106	return 1;
	107	}
	108
	109	void
e1f52a8a	110	mop_get_package_symbols (HV stash, type_filter_t filter, get_package_symbols_cb_t cb, void ud)
d846ade3	111	{
	112	HE *he;
	113
	114	(void)hv_iterinit(stash);
	115
	116	if (filter == TYPE_FILTER_NONE) {
	117	while ( (he = hv_iternext(stash)) ) {
	118	STRLEN keylen;
	119	const char *key = HePV(he, keylen);
	120	if (!cb(key, keylen, HeVAL(he), ud)) {
	121	return;
	122	}
	123	}
	124	return;
	125	}
	126
	127	while ( (he = hv_iternext(stash)) ) {
	128	SV *const gv = HeVAL(he);
	129	SV *sv = NULL;
	130	char *key;
	131	STRLEN keylen;
	132	char *package;
d846ade3	133
	134	switch( SvTYPE(gv) ) {
	135	#ifndef SVt_RV
	136	case SVt_RV:
	137	#endif
	138	case SVt_PV:
	139	case SVt_IV:
	140	/* expand the gv into a real typeglob if it
	141	* contains stub functions and we were asked to
	142	* return CODE symbols */
	143	if (filter == TYPE_FILTER_CODE) {
	144	if (SvROK(gv)) {
8a2e4cdb	145	SV* fq;
d846ade3	146	/* we don't really care about the length,
	147	but that's the API */
	148	key = HePV(he, keylen);
	149	package = HvNAME(stash);
efc98200	150	fq = sv_2mortal(newSVpvf("%s::%s", package, key));
d846ade3	151	sv = (SV *)get_cv(SvPV_nolen(fq), 0);
	152	break;
	153	}
	154
	155	key = HePV(he, keylen);
	156	gv_init((GV *)gv, stash, key, keylen, GV_ADDMULTI);
	157	}
	158	/* fall through */
	159	case SVt_PVGV:
	160	switch (filter) {
	161	case TYPE_FILTER_CODE: sv = (SV *)GvCVu(gv); break;
	162	case TYPE_FILTER_ARRAY: sv = (SV *)GvAV(gv); break;
	163	case TYPE_FILTER_IO: sv = (SV *)GvIO(gv); break;
	164	case TYPE_FILTER_HASH: sv = (SV *)GvHV(gv); break;
	165	case TYPE_FILTER_SCALAR: sv = (SV *)GvSV(gv); break;
	166	default:
	167	croak("Unknown type");
	168	}
	169	break;
	170	default:
	171	continue;
	172	}
	173
	174	if (sv) {
	175	const char *key = HePV(he, keylen);
	176	if (!cb(key, keylen, sv, ud)) {
	177	return;
	178	}
	179	}
	180	}
	181	}
	182
	183	static bool
	184	collect_all_symbols (const char key, STRLEN keylen, SV val, void *ud)
	185	{
	186	HV hash = (HV )ud;
	187
	188	if (!hv_store (hash, key, keylen, newRV_inc(val), 0)) {
	189	croak("failed to store symbol ref");
	190	}
	191
	192	return TRUE;
	193	}
	194
	195	HV *
e1f52a8a	196	mop_get_all_package_symbols (HV *stash, type_filter_t filter)
d846ade3	197	{
d846ade3	198	HV *ret = newHV ();
e1f52a8a	199	mop_get_package_symbols (stash, filter, collect_all_symbols, ret);
d846ade3	200	return ret;
d846ade3	201	}
22932438	202
8a2e4cdb	203	static MGVTBL mop_accessor_vtbl; /* the MAGIC identity */
22932438	204
a69b9501	205	CV*
	206	mop_install_simple_accessor(pTHX_ const char* const fq_name, const char* const key, I32 const keylen, XSPROTO(accessor_impl)){
	207	CV* const xsub = newXS((char*)fq_name, accessor_impl, __FILE__);
	208	SV* const keysv = newSVpvn_share(key, keylen, 0U);
22932438	209
8a2e4cdb	210	sv_magicext((SV*)xsub, keysv, PERL_MAGIC_ext, &mop_accessor_vtbl, NULL, 0);
8a2e4cdb	211	SvREFCNT_dec(keysv); /* sv_magicext() increases refcnt in mg_obj */
a69b9501	212	return xsub;
22932438	213	}
22932438	214
8a2e4cdb	215	static MAGIC*
a69b9501	216	mop_mg_find_by_vtbl(pTHX_ SV* const sv, const MGVTBL* const vtbl){
8a2e4cdb	217	MAGIC* mg;
	218
	219	assert(sv != NULL);
	220	for(mg = SvMAGIC(sv); mg; mg = mg->mg_moremagic){
	221	if(mg->mg_virtual == vtbl){
	222	break;
	223	}
22932438	224	}
8a2e4cdb	225	return mg;
22932438	226	}
22932438	227
a69b9501	228	static SV*
	229	mop_fetch_attr(pTHX_ SV* const self, SV* const key, I32 const create, CV* const cv){
	230	HE* he;
	231	if (!SvROK(self)) {
	232	croak("can't call %s as a class method", GvNAME(CvGV(cv)));
	233	}
	234	if (SvTYPE(SvRV(self)) != SVt_PVHV) {
	235	croak("object is not a hashref");
	236	}
	237	if((he = hv_fetch_ent((HV*)SvRV(self), key, create, 0U))){
	238	return HeVAL(he);
	239	}
	240	return NULL;
	241	}
	242	static SV*
	243	mop_delete_attr(pTHX_ SV* const self, SV* const key, CV* const cv){
	244	SV* sv;
	245	if (!SvROK(self)) {
	246	croak("can't call %s as a class method", GvNAME(CvGV(cv)));
	247	}
	248	if (SvTYPE(SvRV(self)) != SVt_PVHV) {
	249	croak("object is not a hashref");
	250	}
	251	if((sv = hv_delete_ent((HV*)SvRV(self), key, 0, 0U))){
	252	return sv;
	253	}
	254	return NULL;
	255	}
	256
	257	XS(mop_xs_simple_accessor)
22932438	258	{
a69b9501	259	dVAR; dXSARGS;
	260	MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
	261	SV* const key = mg->mg_obj;
	262	SV* attr;
	263	if(items == 1){ /* reader */
	264	attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
	265	}
	266	else if (items == 2){ /* writer */
	267	attr = mop_fetch_attr(aTHX_ ST(0), key, TRUE, cv);
	268	sv_setsv(attr, ST(1));
22932438	269	}
a69b9501	270	else{
	271	croak("expected exactly one or two argument");
	272	}
	273	ST(0) = attr ? attr : &PL_sv_undef;
	274	XSRETURN(1);
22932438	275	}
7ec7b950	276
a69b9501	277
384bb6c9	278	XS(mop_xs_simple_reader)
7ec7b950	279	{
384bb6c9	280	dVAR; dXSARGS;
a69b9501	281	MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
8a2e4cdb	282	SV* const key = mg->mg_obj;
a69b9501	283	SV* attr;
384bb6c9	284
	285	if (items != 1) {
	286	croak("expected exactly one argument");
	287	}
	288
a69b9501	289	attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
	290	ST(0) = attr ? attr : &PL_sv_undef;
	291	XSRETURN(1);
	292	}
7ec7b950	293
a69b9501	294	XS(mop_xs_simple_writer)
	295	{
	296	dVAR; dXSARGS;
	297	MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
	298	SV* const key = mg->mg_obj;
	299	SV* attr;
7ec7b950	300
a69b9501	301	if (items != 2) {
a69b9501	302	croak("expected exactly two argument");
7ec7b950	303	}
7ec7b950	304
a69b9501	305	attr = mop_fetch_attr(aTHX_ ST(0), key, TRUE, cv);
	306	sv_setsv(attr, ST(1));
	307	ST(0) = attr;
	308	XSRETURN(1);
	309	}
	310
	311	XS(mop_xs_simple_clearer)
	312	{
	313	dVAR; dXSARGS;
	314	MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
	315	SV* const key = mg->mg_obj;
	316	SV* attr;
	317
	318	if (items != 1) {
	319	croak("expected exactly one argument");
7ec7b950	320	}
7ec7b950	321
a69b9501	322	attr = mop_delete_attr(aTHX_ ST(0), key, cv);
	323	ST(0) = attr ? attr : &PL_sv_undef;
	324	XSRETURN(1);
	325	}
	326
	327
	328	XS(mop_xs_simple_predicate)
	329	{
	330	dVAR; dXSARGS;
	331	MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
	332	SV* const key = mg->mg_obj;
	333	SV* attr;
	334
	335	if (items != 1) {
	336	croak("expected exactly one argument");
7ec7b950	337	}
7ec7b950	338
a69b9501	339	attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
a69b9501	340	ST(0) = boolSV(attr); /* exists */
7ec7b950	341	XSRETURN(1);
	342	}
	343
a69b9501	344
	345	XS(mop_xs_simple_predicate_for_metaclass)
	346	{
	347	dVAR; dXSARGS;
	348	MAGIC* const mg = mop_mg_find_by_vtbl(aTHX_ (SV*)cv, &mop_accessor_vtbl);
	349	SV* const key = mg->mg_obj;
	350	SV* attr;
	351
	352	if (items != 1) {
	353	croak("expected exactly one argument");
7ec7b950	354	}
7ec7b950	355
a69b9501	356	attr = mop_fetch_attr(aTHX_ ST(0), key, FALSE, cv);
a69b9501	357	ST(0) = boolSV(attr && SvOK(attr)); /* defined */
7ec7b950	358	XSRETURN(1);
7ec7b950	359	}