[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, 2007, 2008 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 {
    _XPV_HEAD;
    _XPVMG_HEAD;
    _XPVCV_COMMON;
};

/*
=head1 Handy Values

=for apidoc AmU||Nullcv
Null CV pointer.

(deprecated - use C<(CV *)NULL> instead)

=head1 CV Manipulation Functions

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

=cut
*/

#ifndef PERL_CORE
#  define Nullcv Null(CV*)
#endif

#define CvSTASH(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash
#define CvSTART(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
#define CvROOT(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
#define CvXSUB(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
#define CvXSUBANY(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
#define CvGV(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv
#define CvFILE(sv)	((XPVCV*)MUTABLE_PTR(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 *const _cvdepth = (const CV *)sv; \
			  assert(SvTYPE(_cvdepth) == SVt_PVCV);	 \
			  &((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \
			}))
#else
#  define CvDEPTH(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xiv_u.xivu_i32
#endif
#define CvPADLIST(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
#define CvOUTSIDE(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
#define CvFLAGS(sv)	((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq

#define CVf_METHOD	0x0001	/* CV is explicitly marked as a method */
#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_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 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	*
1129b882	3	* Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2001,
1129b882	4	* 2002, 2003, 2004, 2005, 2006, 2007, 2008 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 {
20f4945e	14	_XPV_HEAD;
	15	_XPVMG_HEAD;
	16	_XPVCV_COMMON;
79072805	17	};
748a9306	18
954c1994	19	/*
ccfc67b7	20	=head1 Handy Values
ccfc67b7	21
954c1994	22	=for apidoc AmU\|\|Nullcv
	23	Null CV pointer.
	24
3ae1b226	25	(deprecated - use C<(CV *)NULL> instead)
3ae1b226	26
ccfc67b7	27	=head1 CV Manipulation Functions
ccfc67b7	28
954c1994	29	=for apidoc Am\|HV\|CvSTASH\|CV cv
	30	Returns the stash of the CV.
	31
	32	=cut
	33	*/
	34
3ae1b226	35	#ifndef PERL_CORE
	36	# define Nullcv Null(CV*)
	37	#endif
a5f75d66	38
8f629a87	39	#define CvSTASH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash
	40	#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
	41	#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
	42	#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
	43	#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
	44	#define CvGV(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv
	45	#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
a636914a	46	#ifdef USE_ITHREADS
	47	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
	48	#else
	49	# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
	50	#endif
9ec2a764	51	#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083	52	#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
8f629a87	53	# define CvDEPTH(sv) (({const CV const _cvdepth = (const CV *)sv; \
5129b2ca	54	assert(SvTYPE(_cvdepth) == SVt_PVCV); \
7948fc08	55	&((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \
bb172083	56	}))
bb172083	57	#else
8f629a87	58	# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xiv_u.xivu_i32
bb172083	59	#endif
8f629a87	60	#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
	61	#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
	62	#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
	63	#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66	64
5b4563c8	65	#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
5b4563c8	66	#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
5b4563c8	67
	68	#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
	69	#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
	70	#define CVf_CLONED 0x0040 /* a clone of one of those */
	71	#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
	72	#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d	73	* require, eval). */
5b4563c8	74	#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01	75	(esp. useful for special XSUBs) */
5b4563c8	76	#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291	77	#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52	78
d3cea301	79	/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0	80	#define CVf_BUILTIN_ATTRS (CVf_METHOD\|CVf_LVALUE)
a5f75d66	81
	82	#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
	83	#define CvCLONE_on(cv) (CvFLAGS(cv) \|= CVf_CLONE)
	84	#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
	85
	86	#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
	87	#define CvCLONED_on(cv) (CvFLAGS(cv) \|= CVf_CLONED)
	88	#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
	89
	90	#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
	91	#define CvANON_on(cv) (CvFLAGS(cv) \|= CVf_ANON)
	92	#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805	93
07055b4c	94	#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
	95	#define CvUNIQUE_on(cv) (CvFLAGS(cv) \|= CVf_UNIQUE)
	96	#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
8ebc5c01	97
	98	#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
	99	#define CvNODEBUG_on(cv) (CvFLAGS(cv) \|= CVf_NODEBUG)
	100	#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
77a005ab	101
	102	#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
	103	#define CvMETHOD_on(cv) (CvFLAGS(cv) \|= CVf_METHOD)
	104	#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
	105
cd06dffe	106	#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
	107	#define CvLVALUE_on(cv) (CvFLAGS(cv) \|= CVf_LVALUE)
	108	#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
	109
1aff0e91	110	#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
	111	#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
	112	#define CvEVAL_off(cv) CvUNIQUE_off(cv)
	113
3c10abe3	114	/* BEGIN\|CHECK\|INIT\|UNITCHECK\|END */
1aff0e91	115	#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
	116	#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
	117	#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
beab0874	118
	119	#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
	120	#define CvCONST_on(cv) (CvFLAGS(cv) \|= CVf_CONST)
	121	#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029	122
7dafbf52	123	#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
	124	#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) \|= CVf_WEAKOUTSIDE)
	125	#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
	126
d04ba589	127	#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
	128	#define CvISXSUB_on(cv) (CvFLAGS(cv) \|= CVf_ISXSUB)
	129	#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
	130
77004dee	131	/* Flags for newXS_flags */
	132	#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
	133
7dafbf52	134	/*
	135	=head1 CV reference counts and CvOUTSIDE
	136
	137	=for apidoc m\|bool\|CvWEAKOUTSIDE\|CV *cv
	138
	139	Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
	140	CV (if any). Because pointers to anonymous sub prototypes are
	141	stored in C<&> pad slots, it is a possible to get a circular reference,
	142	with the parent pointing to the child and vice-versa. To avoid the
	143	ensuing memory leak, we do not increment the reference count of the CV
	144	pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
	145	has a C<&> pad slot pointing back to us. In this case, we set the
	146	C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
	147	circumstances we should decrement the refcount of the parent when freeing
	148	the child.
	149
eeb8d49e	150	There is a further complication with non-closure anonymous subs (i.e. those
7dafbf52	151	that do not refer to any lexicals outside that sub). In this case, the
	152	anonymous prototype is shared rather than being cloned. This has the
	153	consequence that the parent may be freed while there are still active
	154	children, eg
	155
	156	BEGIN { $a = sub { eval '$x' } }
	157
	158	In this case, the BEGIN is freed immediately after execution since there
	159	are no active references to it: the anon sub prototype has
	160	C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
	161	CV, so it doesn't contribute to BEGIN's refcount either. When $a is
	162	executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
	163	and the freed BEGIN is accessed.
	164
	165	To avoid this, whenever a CV and its associated pad is freed, any
	166	C<&> entries in the pad are explicitly removed from the pad, and if the
	167	refcount of the pointed-to anon sub is still positive, then that
	168	child's C<CvOUTSIDE> is set to point to its grandparent. This will only
	169	occur in the single specific case of a non-closure anon prototype
	170	having one or more active references (such as C<$a> above).
	171
	172	One other thing to consider is that a CV may be merely undefined
	173	rather than freed, eg C<undef &foo>. In this case, its refcount may
	174	not have reached zero, but we still delete its pad and its C<CvROOT> etc.
	175	Since various children may still have their C<CvOUTSIDE> pointing at this
	176	undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
	177	the chain of lexical scopes is unbroken. For example, the following
	178	should print 123:
	179
	180	my $x = 123;
	181	sub tmp { sub { eval '$x' } }
	182	my $a = tmp();
	183	undef &tmp;
	184	print $a->();
	185
	186	=cut
	187	*/
102d3b8a	188
	189	/*
	190	* Local variables:
	191	* c-indentation-style: bsd
	192	* c-basic-offset: 4
	193	* indent-tabs-mode: t
	194	* End:
	195	*
	196	* ex: set ts=8 sts=4 sw=4 noet:
	197	*/