[p5sagit/p5-mst-13.2.git] / cv.h

/*    cv.h
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999,
 *    2000, 2001, 2002, 2003, 2004, 2005, 2006, by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/* This structure must the beginning of XPVFM in sv.h  */

struct xpvcv {
    union {
	NV	xnv_nv;		/* numeric value, if any */
	HV *	xgv_stash;
	struct {
	    U32	xlow;
	    U32	xhigh;
	}	xpad_cop_seq;	/* used by pad.c for cop_sequence */
    }		xnv_u;
    STRLEN	xpv_cur;	/* length of xp_pv as a C string */
    STRLEN	xpv_len;	/* allocated size */
    union {
	IV	xivu_iv;
	UV	xivu_uv;
	void *	xivu_p1;
	I32	xivu_i32;	/* depth, >= 2 indicates recursive call */
	HEK *	xivu_namehek;
    }		xiv_u;
    union {
	MAGIC*	xmg_magic;	/* linked list of magicalness */
	HV*	xmg_ourstash;	/* Stash for our (when SvPAD_OUR is true) */
    } xmg_u;
    HV*		xmg_stash;	/* class package */

    HV *	xcv_stash;
    union {
	OP *	xcv_start;
	ANY	xcv_xsubany;
    }		xcv_start_u;
    union {
	OP *	xcv_root;
	void	(*xcv_xsub) (pTHX_ CV*);
    }		xcv_root_u;
    GV *	xcv_gv;
    char *	xcv_file;
    PADLIST *	xcv_padlist;
    CV *	xcv_outside;
    U32		xcv_outside_seq; /* the COP sequence (at the point of our
				  * compilation) in the lexically enclosing
				  * sub */
    cv_flags_t	xcv_flags;
};

typedef struct {
    STRLEN	xpv_cur;	/* length of xp_pv as a C string */
    STRLEN	xpv_len;	/* allocated size */
    union {
	IV	xivu_iv;
	UV	xivu_uv;
	void *	xivu_p1;
	I32	xivu_i32;	/* depth, >= 2 indicates recursive call */
	HEK *	xivu_namehek;
    }		xiv_u;
    union {
	MAGIC*	xmg_magic;	/* linked list of magicalness */
	HV*	xmg_ourstash;	/* Stash for our (when SvPAD_OUR is true) */
    } xmg_u;
    HV*		xmg_stash;	/* class package */

    HV *	xcv_stash;
    union {
	OP *	xcv_start;
	ANY	xcv_xsubany;
    }		xcv_start_u;
    union {
	OP *	xcv_root;
	void	(*xcv_xsub) (pTHX_ CV*);
    }		xcv_root_u;
    GV *	xcv_gv;
    char *	xcv_file;
    PADLIST *	xcv_padlist;
    CV *	xcv_outside;
    U32		xcv_outside_seq; /* the COP sequence (at the point of our
				  * compilation) in the lexically enclosing
				  * sub */
    cv_flags_t	xcv_flags;
} xpvcv_allocated;

/*
=head1 Handy Values

=for apidoc AmU||Nullcv
Null CV pointer.

=head1 CV Manipulation Functions

=for apidoc Am|HV*|CvSTASH|CV* cv
Returns the stash of the CV.

=cut
*/

#define Nullcv Null(CV*)

#define CvSTASH(sv)	((XPVCV*)SvANY(sv))->xcv_stash
#define CvSTART(sv)	((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start
#define CvROOT(sv)	((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root
#define CvXSUB(sv)	((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub
#define CvXSUBANY(sv)	((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany
#define CvGV(sv)	((XPVCV*)SvANY(sv))->xcv_gv
#define CvFILE(sv)	((XPVCV*)SvANY(sv))->xcv_file
#ifdef USE_ITHREADS
#  define CvFILE_set_from_cop(sv, cop)	(CvFILE(sv) = savepv(CopFILE(cop)))
#else
#  define CvFILE_set_from_cop(sv, cop)	(CvFILE(sv) = CopFILE(cop))
#endif
#define CvFILEGV(sv)	(gv_fetchfile(CvFILE(sv)))
#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
#  define CvDEPTH(sv) (*({const CV *_cv = (CV *)sv; \
			  assert(SvTYPE(_cv) == SVt_PVCV); \
			  &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \
			}))
#else
#  define CvDEPTH(sv)	((XPVCV*)SvANY(sv))->xiv_u.xivu_i32
#endif
#define CvPADLIST(sv)	((XPVCV*)SvANY(sv))->xcv_padlist
#define CvOUTSIDE(sv)	((XPVCV*)SvANY(sv))->xcv_outside
#define CvFLAGS(sv)	((XPVCV*)SvANY(sv))->xcv_flags
#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq

#define CVf_METHOD	0x0001	/* CV is explicitly marked as a method */
#define CVf_LOCKED	0x0002	/* CV locks itself or first arg on entry */
#define CVf_LVALUE	0x0004  /* CV return value can be used as lvalue */
#define CVf_ASSERTION   0x0008  /* CV called only when asserting */

#define CVf_WEAKOUTSIDE	0x0010  /* CvOUTSIDE isn't ref counted */
#define CVf_CLONE	0x0020	/* anon CV uses external lexicals */
#define CVf_CLONED	0x0040	/* a clone of one of those */
#define CVf_ANON	0x0080	/* CvGV() can't be trusted */
#define CVf_UNIQUE	0x0100	/* sub is only called once (eg PL_main_cv,
				 * require, eval). */
#define CVf_NODEBUG	0x0200	/* no DB::sub indirection for this CV
				   (esp. useful for special XSUBs) */
#define CVf_CONST	0x0400  /* inlinable sub */
#define CVf_ISXSUB	0x0800	/* CV is an XSUB, not pure perl.  */

/* This symbol for optimised communication between toke.c and op.c: */
#define CVf_BUILTIN_ATTRS	(CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION)

#define CvCLONE(cv)		(CvFLAGS(cv) & CVf_CLONE)
#define CvCLONE_on(cv)		(CvFLAGS(cv) |= CVf_CLONE)
#define CvCLONE_off(cv)		(CvFLAGS(cv) &= ~CVf_CLONE)

#define CvCLONED(cv)		(CvFLAGS(cv) & CVf_CLONED)
#define CvCLONED_on(cv)		(CvFLAGS(cv) |= CVf_CLONED)
#define CvCLONED_off(cv)	(CvFLAGS(cv) &= ~CVf_CLONED)

#define CvANON(cv)		(CvFLAGS(cv) & CVf_ANON)
#define CvANON_on(cv)		(CvFLAGS(cv) |= CVf_ANON)
#define CvANON_off(cv)		(CvFLAGS(cv) &= ~CVf_ANON)

#define CvUNIQUE(cv)		(CvFLAGS(cv) & CVf_UNIQUE)
#define CvUNIQUE_on(cv)		(CvFLAGS(cv) |= CVf_UNIQUE)
#define CvUNIQUE_off(cv)	(CvFLAGS(cv) &= ~CVf_UNIQUE)

#define CvNODEBUG(cv)		(CvFLAGS(cv) & CVf_NODEBUG)
#define CvNODEBUG_on(cv)	(CvFLAGS(cv) |= CVf_NODEBUG)
#define CvNODEBUG_off(cv)	(CvFLAGS(cv) &= ~CVf_NODEBUG)

#define CvMETHOD(cv)		(CvFLAGS(cv) & CVf_METHOD)
#define CvMETHOD_on(cv)		(CvFLAGS(cv) |= CVf_METHOD)
#define CvMETHOD_off(cv)	(CvFLAGS(cv) &= ~CVf_METHOD)

#define CvLOCKED(cv)		(CvFLAGS(cv) & CVf_LOCKED)
#define CvLOCKED_on(cv)		(CvFLAGS(cv) |= CVf_LOCKED)
#define CvLOCKED_off(cv)	(CvFLAGS(cv) &= ~CVf_LOCKED)

#define CvLVALUE(cv)		(CvFLAGS(cv) & CVf_LVALUE)
#define CvLVALUE_on(cv)		(CvFLAGS(cv) |= CVf_LVALUE)
#define CvLVALUE_off(cv)	(CvFLAGS(cv) &= ~CVf_LVALUE)

#define CvASSERTION(cv)		(CvFLAGS(cv) & CVf_ASSERTION)
#define CvASSERTION_on(cv)	(CvFLAGS(cv) |= CVf_ASSERTION)
#define CvASSERTION_off(cv)	(CvFLAGS(cv) &= ~CVf_ASSERTION)

#define CvEVAL(cv)		(CvUNIQUE(cv) && !SvFAKE(cv))
#define CvEVAL_on(cv)		(CvUNIQUE_on(cv),SvFAKE_off(cv))
#define CvEVAL_off(cv)		CvUNIQUE_off(cv)

/* BEGIN|CHECK|INIT|UNITCHECK|END */
#define CvSPECIAL(cv)		(CvUNIQUE(cv) && SvFAKE(cv))
#define CvSPECIAL_on(cv)	(CvUNIQUE_on(cv),SvFAKE_on(cv))
#define CvSPECIAL_off(cv)	(CvUNIQUE_off(cv),SvFAKE_off(cv))

#define CvCONST(cv)		(CvFLAGS(cv) & CVf_CONST)
#define CvCONST_on(cv)		(CvFLAGS(cv) |= CVf_CONST)
#define CvCONST_off(cv)		(CvFLAGS(cv) &= ~CVf_CONST)

#define CvWEAKOUTSIDE(cv)	(CvFLAGS(cv) & CVf_WEAKOUTSIDE)
#define CvWEAKOUTSIDE_on(cv)	(CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
#define CvWEAKOUTSIDE_off(cv)	(CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)

#define CvISXSUB(cv)		(CvFLAGS(cv) & CVf_ISXSUB)
#define CvISXSUB_on(cv)		(CvFLAGS(cv) |= CVf_ISXSUB)
#define CvISXSUB_off(cv)	(CvFLAGS(cv) &= ~CVf_ISXSUB)

/* Flags for newXS_flags  */
#define XS_DYNAMIC_FILENAME	0x01	/* The filename isn't static  */

/*
=head1 CV reference counts and CvOUTSIDE

=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv

Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
CV (if any). Because pointers to anonymous sub prototypes are
stored in C<&> pad slots, it is a possible to get a circular reference,
with the parent pointing to the child and vice-versa. To avoid the
ensuing memory leak, we do not increment the reference count of the CV
pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
has a C<&> pad slot pointing back to us. In this case, we set the
C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
circumstances we should decrement the refcount of the parent when freeing
the child.

There is a further complication with non-closure anonymous subs (i.e. those
that do not refer to any lexicals outside that sub). In this case, the
anonymous prototype is shared rather than being cloned. This has the
consequence that the parent may be freed while there are still active
children, eg

    BEGIN { $a = sub { eval '$x' } }

In this case, the BEGIN is freed immediately after execution since there
are no active references to it: the anon sub prototype has
C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
CV, so it doesn't contribute to BEGIN's refcount either.  When $a is
executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
and the freed BEGIN is accessed.

To avoid this, whenever a CV and its associated pad is freed, any
C<&> entries in the pad are explicitly removed from the pad, and if the
refcount of the pointed-to anon sub is still positive, then that
child's C<CvOUTSIDE> is set to point to its grandparent. This will only
occur in the single specific case of a non-closure anon prototype
having one or more active references (such as C<$a> above).

One other thing to consider is that a CV may be merely undefined
rather than freed, eg C<undef &foo>. In this case, its refcount may
not have reached zero, but we still delete its pad and its C<CvROOT> etc.
Since various children may still have their C<CvOUTSIDE> pointing at this
undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
the chain of lexical scopes is unbroken. For example, the following
should print 123:

    my $x = 123;
    sub tmp { sub { eval '$x' } }
    my $a = tmp();
    undef &tmp;
    print  $a->();

=cut
*/

/*
 * Local variables:
 * c-indentation-style: bsd
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 *
 * ex: set ts=8 sts=4 sw=4 noet:
 */
Commit	Line	Data
a0d0e21e	1	/* cv.h
79072805	2	*
4bb101f2	3	* Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999,
bf53b3a5	4	* 2000, 2001, 2002, 2003, 2004, 2005, 2006, by Larry Wall and others
79072805	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	*
79072805	9	*/
79072805	10
7c60e434	11	/* This structure must the beginning of XPVFM in sv.h */
44a8e56a	12
79072805	13	struct xpvcv {
58430790	14	union {
	15	NV xnv_nv; /* numeric value, if any */
	16	HV * xgv_stash;
3441fb63	17	struct {
	18	U32 xlow;
	19	U32 xhigh;
	20	} xpad_cop_seq; /* used by pad.c for cop_sequence */
58430790	21	} xnv_u;
79072805	22	STRLEN xpv_cur; /* length of xp_pv as a C string */
79072805	23	STRLEN xpv_len; /* allocated size */
e4305a63	24	union {
bb172083	25	IV xivu_iv;
311a25d9	26	UV xivu_uv;
311a25d9	27	void * xivu_p1;
bb172083	28	I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12	29	HEK * xivu_namehek;
311a25d9	30	} xiv_u;
e736a858	31	union {
	32	MAGIC* xmg_magic; /* linked list of magicalness */
	33	HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
	34	} xmg_u;
79072805	35	HV* xmg_stash; /* class package */
	36
	37	HV * xcv_stash;
bf53b3a5	38	union {
	39	OP * xcv_start;
	40	ANY xcv_xsubany;
	41	} xcv_start_u;
d04ba589	42	union {
	43	OP * xcv_root;
	44	void (xcv_xsub) (pTHX_ CV);
	45	} xcv_root_u;
8990e307	46	GV * xcv_gv;
57843af0	47	char * xcv_file;
dd2155a4	48	PADLIST * xcv_padlist;
748a9306	49	CV * xcv_outside;
a3985cdc	50	U32 xcv_outside_seq; /* the COP sequence (at the point of our
	51	* compilation) in the lexically enclosing
	52	* sub */
bb172083	53	cv_flags_t xcv_flags;
79072805	54	};
748a9306	55
c84c4652	56	typedef struct {
	57	STRLEN xpv_cur; /* length of xp_pv as a C string */
	58	STRLEN xpv_len; /* allocated size */
	59	union {
	60	IV xivu_iv;
	61	UV xivu_uv;
	62	void * xivu_p1;
	63	I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12	64	HEK * xivu_namehek;
c84c4652	65	} xiv_u;
e736a858	66	union {
	67	MAGIC* xmg_magic; /* linked list of magicalness */
	68	HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
	69	} xmg_u;
c84c4652	70	HV* xmg_stash; /* class package */
	71
	72	HV * xcv_stash;
	73	union {
	74	OP * xcv_start;
	75	ANY xcv_xsubany;
	76	} xcv_start_u;
	77	union {
	78	OP * xcv_root;
	79	void (xcv_xsub) (pTHX_ CV);
	80	} xcv_root_u;
	81	GV * xcv_gv;
	82	char * xcv_file;
	83	PADLIST * xcv_padlist;
	84	CV * xcv_outside;
	85	U32 xcv_outside_seq; /* the COP sequence (at the point of our
	86	* compilation) in the lexically enclosing
	87	* sub */
	88	cv_flags_t xcv_flags;
	89	} xpvcv_allocated;
	90
954c1994	91	/*
ccfc67b7	92	=head1 Handy Values
ccfc67b7	93
954c1994	94	=for apidoc AmU\|\|Nullcv
	95	Null CV pointer.
	96
ccfc67b7	97	=head1 CV Manipulation Functions
ccfc67b7	98
954c1994	99	=for apidoc Am\|HV\|CvSTASH\|CV cv
	100	Returns the stash of the CV.
	101
	102	=cut
	103	*/
	104
79072805	105	#define Nullcv Null(CV*)
a5f75d66	106
79072805	107	#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
bf53b3a5	108	#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start
d04ba589	109	#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root
d04ba589	110	#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub
bf53b3a5	111	#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany
8990e307	112	#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0	113	#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
a636914a	114	#ifdef USE_ITHREADS
	115	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
	116	#else
	117	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
	118	#endif
9ec2a764	119	#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083	120	#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
	121	# define CvDEPTH(sv) (({const CV _cv = (CV *)sv; \
	122	assert(SvTYPE(_cv) == SVt_PVCV); \
	123	&((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \
	124	}))
	125	#else
	126	# define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32
	127	#endif
79072805	128	#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306	129	#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66	130	#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc	131	#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66	132
5b4563c8	133	#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
	134	#define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */
	135	#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
	136	#define CVf_ASSERTION 0x0008 /* CV called only when asserting */
	137
	138	#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
	139	#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
	140	#define CVf_CLONED 0x0040 /* a clone of one of those */
	141	#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
	142	#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d	143	* require, eval). */
5b4563c8	144	#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01	145	(esp. useful for special XSUBs) */
5b4563c8	146	#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291	147	#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52	148
d3cea301	149	/* This symbol for optimised communication between toke.c and op.c: */
06492da6	150	#define CVf_BUILTIN_ATTRS (CVf_METHOD\|CVf_LOCKED\|CVf_LVALUE\|CVf_ASSERTION)
a5f75d66	151
	152	#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
	153	#define CvCLONE_on(cv) (CvFLAGS(cv) \|= CVf_CLONE)
	154	#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
	155
	156	#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
	157	#define CvCLONED_on(cv) (CvFLAGS(cv) \|= CVf_CLONED)
	158	#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
	159
	160	#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
	161	#define CvANON_on(cv) (CvFLAGS(cv) \|= CVf_ANON)
	162	#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805	163
07055b4c	164	#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
	165	#define CvUNIQUE_on(cv) (CvFLAGS(cv) \|= CVf_UNIQUE)
	166	#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
8ebc5c01	167
	168	#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
	169	#define CvNODEBUG_on(cv) (CvFLAGS(cv) \|= CVf_NODEBUG)
	170	#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
77a005ab	171
	172	#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
	173	#define CvMETHOD_on(cv) (CvFLAGS(cv) \|= CVf_METHOD)
	174	#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
	175
	176	#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
	177	#define CvLOCKED_on(cv) (CvFLAGS(cv) \|= CVf_LOCKED)
	178	#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91	179
cd06dffe	180	#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
	181	#define CvLVALUE_on(cv) (CvFLAGS(cv) \|= CVf_LVALUE)
	182	#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
	183
06492da6	184	#define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION)
	185	#define CvASSERTION_on(cv) (CvFLAGS(cv) \|= CVf_ASSERTION)
	186	#define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION)
	187
1aff0e91	188	#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
	189	#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
	190	#define CvEVAL_off(cv) CvUNIQUE_off(cv)
	191
3c10abe3	192	/* BEGIN\|CHECK\|INIT\|UNITCHECK\|END */
1aff0e91	193	#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
	194	#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
	195	#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
beab0874	196
	197	#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
	198	#define CvCONST_on(cv) (CvFLAGS(cv) \|= CVf_CONST)
	199	#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029	200
7dafbf52	201	#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
	202	#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) \|= CVf_WEAKOUTSIDE)
	203	#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
	204
d04ba589	205	#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
	206	#define CvISXSUB_on(cv) (CvFLAGS(cv) \|= CVf_ISXSUB)
	207	#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
	208
77004dee	209	/* Flags for newXS_flags */
	210	#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
	211
7dafbf52	212	/*
	213	=head1 CV reference counts and CvOUTSIDE
	214
	215	=for apidoc m\|bool\|CvWEAKOUTSIDE\|CV *cv
	216
	217	Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
	218	CV (if any). Because pointers to anonymous sub prototypes are
	219	stored in C<&> pad slots, it is a possible to get a circular reference,
	220	with the parent pointing to the child and vice-versa. To avoid the
	221	ensuing memory leak, we do not increment the reference count of the CV
	222	pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
	223	has a C<&> pad slot pointing back to us. In this case, we set the
	224	C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
	225	circumstances we should decrement the refcount of the parent when freeing
	226	the child.
	227
eeb8d49e	228	There is a further complication with non-closure anonymous subs (i.e. those
7dafbf52	229	that do not refer to any lexicals outside that sub). In this case, the
	230	anonymous prototype is shared rather than being cloned. This has the
	231	consequence that the parent may be freed while there are still active
	232	children, eg
	233
	234	BEGIN { $a = sub { eval '$x' } }
	235
	236	In this case, the BEGIN is freed immediately after execution since there
	237	are no active references to it: the anon sub prototype has
	238	C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
	239	CV, so it doesn't contribute to BEGIN's refcount either. When $a is
	240	executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
	241	and the freed BEGIN is accessed.
	242
	243	To avoid this, whenever a CV and its associated pad is freed, any
	244	C<&> entries in the pad are explicitly removed from the pad, and if the
	245	refcount of the pointed-to anon sub is still positive, then that
	246	child's C<CvOUTSIDE> is set to point to its grandparent. This will only
	247	occur in the single specific case of a non-closure anon prototype
	248	having one or more active references (such as C<$a> above).
	249
	250	One other thing to consider is that a CV may be merely undefined
	251	rather than freed, eg C<undef &foo>. In this case, its refcount may
	252	not have reached zero, but we still delete its pad and its C<CvROOT> etc.
	253	Since various children may still have their C<CvOUTSIDE> pointing at this
	254	undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
	255	the chain of lexical scopes is unbroken. For example, the following
	256	should print 123:
	257
	258	my $x = 123;
	259	sub tmp { sub { eval '$x' } }
	260	my $a = tmp();
	261	undef &tmp;
	262	print $a->();
	263
	264	=cut
	265	*/
102d3b8a	266
	267	/*
	268	* Local variables:
	269	* c-indentation-style: bsd
	270	* c-basic-offset: 4
	271	* indent-tabs-mode: t
	272	* End:
	273	*
	274	* ex: set ts=8 sts=4 sw=4 noet:
	275	*/