[perl5.git] / cv.h

/*    cv.h
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000,
 *    2001, 2002, 2003, 2004, 2005, 2006, 2007, 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 */
	struct {
	    U32 xbm_previous;	/* how many characters in string before rare? */
	    U8	xbm_flags;
	    U8	xbm_rare;	/* rarest character in string */
	}	xbm_s;		/* fields from PVBM */
    }		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 ||	 \
				 SvTYPE(_cv) == SVt_PVFM);	 \
			  &((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_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)

#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 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	*
bc641c27 NC	3	* Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000,
bc641c27 NC	4	* 2001, 2002, 2003, 2004, 2005, 2006, 2007, by Larry Wall and others
79072805 LW	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 LW	9	*/
79072805 LW	10
7c60e434	11	/* This structure must the beginning of XPVFM in sv.h */
44a8e56a	12
79072805	13	struct xpvcv {
58430790 NC	14	union {
	15	NV xnv_nv; /* numeric value, if any */
	16	HV * xgv_stash;
3441fb63 NC	17	struct {
	18	U32 xlow;
	19	U32 xhigh;
	20	} xpad_cop_seq; /* used by pad.c for cop_sequence */
8eeaf79a NC	21	struct {
	22	U32 xbm_previous; /* how many characters in string before rare? */
	23	U8 xbm_flags;
	24	U8 xbm_rare; /* rarest character in string */
	25	} xbm_s; /* fields from PVBM */
58430790	26	} xnv_u;
79072805 LW	27	STRLEN xpv_cur; /* length of xp_pv as a C string */
79072805 LW	28	STRLEN xpv_len; /* allocated size */
e4305a63	29	union {
bb172083	30	IV xivu_iv;
311a25d9 NC	31	UV xivu_uv;
311a25d9 NC	32	void * xivu_p1;
bb172083	33	I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12	34	HEK * xivu_namehek;
311a25d9	35	} xiv_u;
e736a858 NC	36	union {
	37	MAGIC* xmg_magic; /* linked list of magicalness */
	38	HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
	39	} xmg_u;
79072805 LW	40	HV* xmg_stash; /* class package */
	41
	42	HV * xcv_stash;
bf53b3a5 NC	43	union {
	44	OP * xcv_start;
	45	ANY xcv_xsubany;
	46	} xcv_start_u;
d04ba589 NC	47	union {
	48	OP * xcv_root;
	49	void (xcv_xsub) (pTHX_ CV);
	50	} xcv_root_u;
8990e307	51	GV * xcv_gv;
57843af0	52	char * xcv_file;
dd2155a4	53	PADLIST * xcv_padlist;
748a9306	54	CV * xcv_outside;
a3985cdc DM	55	U32 xcv_outside_seq; /* the COP sequence (at the point of our
	56	* compilation) in the lexically enclosing
	57	* sub */
bb172083	58	cv_flags_t xcv_flags;
79072805	59	};
748a9306	60
c84c4652 NC	61	typedef struct {
	62	STRLEN xpv_cur; /* length of xp_pv as a C string */
	63	STRLEN xpv_len; /* allocated size */
	64	union {
	65	IV xivu_iv;
	66	UV xivu_uv;
	67	void * xivu_p1;
	68	I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12	69	HEK * xivu_namehek;
c84c4652	70	} xiv_u;
e736a858 NC	71	union {
	72	MAGIC* xmg_magic; /* linked list of magicalness */
	73	HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
	74	} xmg_u;
c84c4652 NC	75	HV* xmg_stash; /* class package */
	76
	77	HV * xcv_stash;
	78	union {
	79	OP * xcv_start;
	80	ANY xcv_xsubany;
	81	} xcv_start_u;
	82	union {
	83	OP * xcv_root;
	84	void (xcv_xsub) (pTHX_ CV);
	85	} xcv_root_u;
	86	GV * xcv_gv;
	87	char * xcv_file;
	88	PADLIST * xcv_padlist;
	89	CV * xcv_outside;
	90	U32 xcv_outside_seq; /* the COP sequence (at the point of our
	91	* compilation) in the lexically enclosing
	92	* sub */
	93	cv_flags_t xcv_flags;
	94	} xpvcv_allocated;
	95
954c1994	96	/*
ccfc67b7 JH	97	=head1 Handy Values
ccfc67b7 JH	98
954c1994 GS	99	=for apidoc AmU\|\|Nullcv
	100	Null CV pointer.
	101
ccfc67b7 JH	102	=head1 CV Manipulation Functions
ccfc67b7 JH	103
954c1994 GS	104	=for apidoc Am\|HV\|CvSTASH\|CV cv
	105	Returns the stash of the CV.
	106
	107	=cut
	108	*/
	109
79072805	110	#define Nullcv Null(CV*)
a5f75d66	111
79072805	112	#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
bf53b3a5	113	#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start
d04ba589 NC	114	#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root
d04ba589 NC	115	#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub
bf53b3a5	116	#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany
8990e307	117	#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0	118	#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
a636914a RH	119	#ifdef USE_ITHREADS
	120	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
	121	#else
	122	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
	123	#endif
9ec2a764	124	#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083 NC	125	#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
bb172083 NC	126	# define CvDEPTH(sv) (({const CV _cv = (CV *)sv; \
766e8246 NC	127	assert(SvTYPE(_cv) == SVt_PVCV \|\| \
766e8246 NC	128	SvTYPE(_cv) == SVt_PVFM); \
bb172083 NC	129	&((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \
	130	}))
	131	#else
	132	# define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32
	133	#endif
79072805	134	#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306	135	#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66	136	#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc	137	#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66	138
5b4563c8 NC	139	#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
	140	#define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */
	141	#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
5b4563c8 NC	142
	143	#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
	144	#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
	145	#define CVf_CLONED 0x0040 /* a clone of one of those */
	146	#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
	147	#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d	148	* require, eval). */
5b4563c8	149	#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01	150	(esp. useful for special XSUBs) */
5b4563c8	151	#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291	152	#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52	153
d3cea301	154	/* This symbol for optimised communication between toke.c and op.c: */
584420f0	155	#define CVf_BUILTIN_ATTRS (CVf_METHOD\|CVf_LOCKED\|CVf_LVALUE)
a5f75d66 AD	156
	157	#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
	158	#define CvCLONE_on(cv) (CvFLAGS(cv) \|= CVf_CLONE)
	159	#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
	160
	161	#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
	162	#define CvCLONED_on(cv) (CvFLAGS(cv) \|= CVf_CLONED)
	163	#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
	164
	165	#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
	166	#define CvANON_on(cv) (CvFLAGS(cv) \|= CVf_ANON)
	167	#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805	168
07055b4c CS	169	#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
	170	#define CvUNIQUE_on(cv) (CvFLAGS(cv) \|= CVf_UNIQUE)
	171	#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
8ebc5c01	172
	173	#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
	174	#define CvNODEBUG_on(cv) (CvFLAGS(cv) \|= CVf_NODEBUG)
	175	#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
77a005ab MB	176
	177	#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
	178	#define CvMETHOD_on(cv) (CvFLAGS(cv) \|= CVf_METHOD)
	179	#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
	180
	181	#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
	182	#define CvLOCKED_on(cv) (CvFLAGS(cv) \|= CVf_LOCKED)
	183	#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91	184
cd06dffe GS	185	#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
	186	#define CvLVALUE_on(cv) (CvFLAGS(cv) \|= CVf_LVALUE)
	187	#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
	188
1aff0e91 GS	189	#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
	190	#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
	191	#define CvEVAL_off(cv) CvUNIQUE_off(cv)
	192
3c10abe3	193	/* BEGIN\|CHECK\|INIT\|UNITCHECK\|END */
1aff0e91 GS	194	#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
	195	#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
	196	#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
beab0874 JT	197
	198	#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
	199	#define CvCONST_on(cv) (CvFLAGS(cv) \|= CVf_CONST)
	200	#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029	201
7dafbf52 DM	202	#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
	203	#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) \|= CVf_WEAKOUTSIDE)
	204	#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
	205
d04ba589 NC	206	#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
	207	#define CvISXSUB_on(cv) (CvFLAGS(cv) \|= CVf_ISXSUB)
	208	#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
	209
77004dee NC	210	/* Flags for newXS_flags */
	211	#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
	212
7dafbf52 DM	213	/*
	214	=head1 CV reference counts and CvOUTSIDE
	215
	216	=for apidoc m\|bool\|CvWEAKOUTSIDE\|CV *cv
	217
	218	Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
	219	CV (if any). Because pointers to anonymous sub prototypes are
	220	stored in C<&> pad slots, it is a possible to get a circular reference,
	221	with the parent pointing to the child and vice-versa. To avoid the
	222	ensuing memory leak, we do not increment the reference count of the CV
	223	pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
	224	has a C<&> pad slot pointing back to us. In this case, we set the
	225	C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
	226	circumstances we should decrement the refcount of the parent when freeing
	227	the child.
	228
eeb8d49e	229	There is a further complication with non-closure anonymous subs (i.e. those
7dafbf52 DM	230	that do not refer to any lexicals outside that sub). In this case, the
	231	anonymous prototype is shared rather than being cloned. This has the
	232	consequence that the parent may be freed while there are still active
	233	children, eg
	234
	235	BEGIN { $a = sub { eval '$x' } }
	236
	237	In this case, the BEGIN is freed immediately after execution since there
	238	are no active references to it: the anon sub prototype has
	239	C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
	240	CV, so it doesn't contribute to BEGIN's refcount either. When $a is
	241	executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
	242	and the freed BEGIN is accessed.
	243
	244	To avoid this, whenever a CV and its associated pad is freed, any
	245	C<&> entries in the pad are explicitly removed from the pad, and if the
	246	refcount of the pointed-to anon sub is still positive, then that
	247	child's C<CvOUTSIDE> is set to point to its grandparent. This will only
	248	occur in the single specific case of a non-closure anon prototype
	249	having one or more active references (such as C<$a> above).
	250
	251	One other thing to consider is that a CV may be merely undefined
	252	rather than freed, eg C<undef &foo>. In this case, its refcount may
	253	not have reached zero, but we still delete its pad and its C<CvROOT> etc.
	254	Since various children may still have their C<CvOUTSIDE> pointing at this
	255	undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
	256	the chain of lexical scopes is unbroken. For example, the following
	257	should print 123:
	258
	259	my $x = 123;
	260	sub tmp { sub { eval '$x' } }
	261	my $a = tmp();
	262	undef &tmp;
	263	print $a->();
	264
	265	=cut
	266	*/
102d3b8a NC	267
	268	/*
	269	* Local variables:
	270	* c-indentation-style: bsd
	271	* c-basic-offset: 4
	272	* indent-tabs-mode: t
	273	* End:
	274	*
	275	* ex: set ts=8 sts=4 sw=4 noet:
	276	*/