[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, 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 match XPVCV in B/C.pm and the beginning of XPVFM
 * in sv.h  */

struct xpvcv {
    char *	xpv_pv;		/* pointer to malloced string (for prototype) */
    STRLEN	xpv_cur;	/* length of xp_pv as a C string */
    STRLEN	xpv_len;	/* allocated size */
    IV		xof_off;	/* integer value */
    NV		xnv_nv;		/* numeric value, if any */
    MAGIC*	xmg_magic;	/* magic for scalar array */
    HV*		xmg_stash;	/* class package */

    HV *	xcv_stash;
    OP *	xcv_start;
    OP *	xcv_root;
    void	(*xcv_xsub) (pTHX_ CV*);
    ANY		xcv_xsubany;
    GV *	xcv_gv;
    char *	xcv_file;
    long	xcv_depth;	/* >= 2 indicates recursive call */
    PADLIST *	xcv_padlist;
    CV *	xcv_outside;
    cv_flags_t	xcv_flags;
    U32		xcv_outside_seq; /* the COP sequence (at the point of our
				  * compilation) in the lexically enclosing
				  * sub */
};

/*
=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
#define CvROOT(sv)	((XPVCV*)SvANY(sv))->xcv_root
#define CvXSUB(sv)	((XPVCV*)SvANY(sv))->xcv_xsub
#define CvXSUBANY(sv)	((XPVCV*)SvANY(sv))->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)))
#define CvDEPTH(sv)	((XPVCV*)SvANY(sv))->xcv_depth
#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_CLONE	0x0001	/* anon CV uses external lexicals */
#define CVf_CLONED	0x0002	/* a clone of one of those */
#define CVf_ANON	0x0004	/* CvGV() can't be trusted */
#define CVf_OLDSTYLE	0x0008
#define CVf_UNIQUE	0x0010	/* sub is only called once (eg PL_main_cv,
				 * require, eval). Not to be confused
				 * with the GVf_UNIQUE flag associated
				 * with the :unique attribute */
#define CVf_NODEBUG	0x0020	/* no DB::sub indirection for this CV
				   (esp. useful for special XSUBs) */
#define CVf_METHOD	0x0040	/* CV is explicitly marked as a method */
#define CVf_LOCKED	0x0080	/* CV locks itself or first arg on entry */
#define CVf_LVALUE	0x0100  /* CV return value can be used as lvalue */
#define CVf_CONST	0x0200  /* inlinable sub */
#define CVf_WEAKOUTSIDE	0x0400  /* CvOUTSIDE isn't ref counted */
#define CVf_ASSERTION   0x0800  /* CV called only when asserting */

/* 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)

#ifdef PERL_XSUB_OLDSTYLE
#define CvOLDSTYLE(cv)		(CvFLAGS(cv) & CVf_OLDSTYLE)
#define CvOLDSTYLE_on(cv)	(CvFLAGS(cv) |= CVf_OLDSTYLE)
#define CvOLDSTYLE_off(cv)	(CvFLAGS(cv) &= ~CVf_OLDSTYLE)
#endif

#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|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)


/*
=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 (ie 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
*/
Commit	Line	Data
a0d0e21e	1	/* cv.h
79072805	2	*
4bb101f2	3	* Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999,
b5f8cc5c	4	* 2000, 2001, 2002, 2003, 2004, 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
fd40b977	11	/* This structure must match XPVCV in B/C.pm and the beginning of XPVFM
57843af0	12	* in sv.h */
44a8e56a	13
79072805	14	struct xpvcv {
b84cd2cb	15	char * xpv_pv; /* pointer to malloced string (for prototype) */
79072805	16	STRLEN xpv_cur; /* length of xp_pv as a C string */
79072805	17	STRLEN xpv_len; /* allocated size */
a0d0e21e	18	IV xof_off; /* integer value */
65202027	19	NV xnv_nv; /* numeric value, if any */
79072805	20	MAGIC* xmg_magic; /* magic for scalar array */
	21	HV* xmg_stash; /* class package */
	22
	23	HV * xcv_stash;
	24	OP * xcv_start;
	25	OP * xcv_root;
acfe0abc	26	void (xcv_xsub) (pTHX_ CV);
a0d0e21e	27	ANY xcv_xsubany;
8990e307	28	GV * xcv_gv;
57843af0	29	char * xcv_file;
b195d487	30	long xcv_depth; /* >= 2 indicates recursive call */
dd2155a4	31	PADLIST * xcv_padlist;
748a9306	32	CV * xcv_outside;
77a005ab	33	cv_flags_t xcv_flags;
a3985cdc	34	U32 xcv_outside_seq; /* the COP sequence (at the point of our
	35	* compilation) in the lexically enclosing
	36	* sub */
79072805	37	};
748a9306	38
954c1994	39	/*
ccfc67b7	40	=head1 Handy Values
ccfc67b7	41
954c1994	42	=for apidoc AmU\|\|Nullcv
	43	Null CV pointer.
	44
ccfc67b7	45	=head1 CV Manipulation Functions
ccfc67b7	46
954c1994	47	=for apidoc Am\|HV\|CvSTASH\|CV cv
	48	Returns the stash of the CV.
	49
	50	=cut
	51	*/
	52
79072805	53	#define Nullcv Null(CV*)
a5f75d66	54
79072805	55	#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
	56	#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start
	57	#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root
a0d0e21e	58	#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_xsub
a0d0e21e	59	#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_xsubany
8990e307	60	#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0	61	#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
a636914a	62	#ifdef USE_ITHREADS
	63	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
	64	#else
	65	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
	66	#endif
9ec2a764	67	#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
79072805	68	#define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xcv_depth
79072805	69	#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306	70	#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66	71	#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc	72	#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66	73
77a005ab	74	#define CVf_CLONE 0x0001 /* anon CV uses external lexicals */
	75	#define CVf_CLONED 0x0002 /* a clone of one of those */
	76	#define CVf_ANON 0x0004 /* CvGV() can't be trusted */
	77	#define CVf_OLDSTYLE 0x0008
6909cc55	78	#define CVf_UNIQUE 0x0010 /* sub is only called once (eg PL_main_cv,
	79	* require, eval). Not to be confused
	80	* with the GVf_UNIQUE flag associated
	81	* with the :unique attribute */
77a005ab	82	#define CVf_NODEBUG 0x0020 /* no DB::sub indirection for this CV
8ebc5c01	83	(esp. useful for special XSUBs) */
77a005ab	84	#define CVf_METHOD 0x0040 /* CV is explicitly marked as a method */
77a005ab	85	#define CVf_LOCKED 0x0080 /* CV locks itself or first arg on entry */
cd06dffe	86	#define CVf_LVALUE 0x0100 /* CV return value can be used as lvalue */
beab0874	87	#define CVf_CONST 0x0200 /* inlinable sub */
7dafbf52	88	#define CVf_WEAKOUTSIDE 0x0400 /* CvOUTSIDE isn't ref counted */
06492da6	89	#define CVf_ASSERTION 0x0800 /* CV called only when asserting */
7dafbf52	90
d3cea301	91	/* This symbol for optimised communication between toke.c and op.c: */
06492da6	92	#define CVf_BUILTIN_ATTRS (CVf_METHOD\|CVf_LOCKED\|CVf_LVALUE\|CVf_ASSERTION)
a5f75d66	93
	94	#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
	95	#define CvCLONE_on(cv) (CvFLAGS(cv) \|= CVf_CLONE)
	96	#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
	97
	98	#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
	99	#define CvCLONED_on(cv) (CvFLAGS(cv) \|= CVf_CLONED)
	100	#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
	101
	102	#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
	103	#define CvANON_on(cv) (CvFLAGS(cv) \|= CVf_ANON)
	104	#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805	105
67caa1fe	106	#ifdef PERL_XSUB_OLDSTYLE
a5f75d66	107	#define CvOLDSTYLE(cv) (CvFLAGS(cv) & CVf_OLDSTYLE)
	108	#define CvOLDSTYLE_on(cv) (CvFLAGS(cv) \|= CVf_OLDSTYLE)
	109	#define CvOLDSTYLE_off(cv) (CvFLAGS(cv) &= ~CVf_OLDSTYLE)
67caa1fe	110	#endif
07055b4c	111
	112	#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
	113	#define CvUNIQUE_on(cv) (CvFLAGS(cv) \|= CVf_UNIQUE)
	114	#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
8ebc5c01	115
	116	#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
	117	#define CvNODEBUG_on(cv) (CvFLAGS(cv) \|= CVf_NODEBUG)
	118	#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
77a005ab	119
	120	#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
	121	#define CvMETHOD_on(cv) (CvFLAGS(cv) \|= CVf_METHOD)
	122	#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
	123
	124	#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
	125	#define CvLOCKED_on(cv) (CvFLAGS(cv) \|= CVf_LOCKED)
	126	#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91	127
cd06dffe	128	#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
	129	#define CvLVALUE_on(cv) (CvFLAGS(cv) \|= CVf_LVALUE)
	130	#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
	131
06492da6	132	#define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION)
	133	#define CvASSERTION_on(cv) (CvFLAGS(cv) \|= CVf_ASSERTION)
	134	#define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION)
	135
1aff0e91	136	#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
	137	#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
	138	#define CvEVAL_off(cv) CvUNIQUE_off(cv)
	139
bec31f9a	140	/* BEGIN\|CHECK\|INIT\|END */
1aff0e91	141	#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
	142	#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
	143	#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
beab0874	144
	145	#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
	146	#define CvCONST_on(cv) (CvFLAGS(cv) \|= CVf_CONST)
	147	#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029	148
7dafbf52	149	#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
	150	#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) \|= CVf_WEAKOUTSIDE)
	151	#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
	152
	153
	154	/*
	155	=head1 CV reference counts and CvOUTSIDE
	156
	157	=for apidoc m\|bool\|CvWEAKOUTSIDE\|CV *cv
	158
	159	Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
	160	CV (if any). Because pointers to anonymous sub prototypes are
	161	stored in C<&> pad slots, it is a possible to get a circular reference,
	162	with the parent pointing to the child and vice-versa. To avoid the
	163	ensuing memory leak, we do not increment the reference count of the CV
	164	pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
	165	has a C<&> pad slot pointing back to us. In this case, we set the
	166	C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
	167	circumstances we should decrement the refcount of the parent when freeing
	168	the child.
	169
	170	There is a further complication with non-closure anonymous subs (ie those
	171	that do not refer to any lexicals outside that sub). In this case, the
	172	anonymous prototype is shared rather than being cloned. This has the
	173	consequence that the parent may be freed while there are still active
	174	children, eg
	175
	176	BEGIN { $a = sub { eval '$x' } }
	177
	178	In this case, the BEGIN is freed immediately after execution since there
	179	are no active references to it: the anon sub prototype has
	180	C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
	181	CV, so it doesn't contribute to BEGIN's refcount either. When $a is
	182	executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
	183	and the freed BEGIN is accessed.
	184
	185	To avoid this, whenever a CV and its associated pad is freed, any
	186	C<&> entries in the pad are explicitly removed from the pad, and if the
	187	refcount of the pointed-to anon sub is still positive, then that
	188	child's C<CvOUTSIDE> is set to point to its grandparent. This will only
	189	occur in the single specific case of a non-closure anon prototype
	190	having one or more active references (such as C<$a> above).
	191
	192	One other thing to consider is that a CV may be merely undefined
	193	rather than freed, eg C<undef &foo>. In this case, its refcount may
	194	not have reached zero, but we still delete its pad and its C<CvROOT> etc.
	195	Since various children may still have their C<CvOUTSIDE> pointing at this
	196	undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
	197	the chain of lexical scopes is unbroken. For example, the following
	198	should print 123:
	199
	200	my $x = 123;
	201	sub tmp { sub { eval '$x' } }
	202	my $a = tmp();
	203	undef &tmp;
	204	print $a->();
	205
	206	=cut
	207	*/