staticperl/perl/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;
#ifdef USE_5005THREADS
    perl_mutex *xcv_mutexp;
    struct perl_thread *xcv_owner;      /* current owner thread */
#endif /* USE_5005THREADS */
    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
#ifdef USE_5005THREADS
#define CvMUTEXP(sv)    ((XPVCV*)SvANY(sv))->xcv_mutexp
#define CvOWNER(sv)     ((XPVCV*)SvANY(sv))->xcv_owner
#endif /* USE_5005THREADS */
#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 */

/* 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)

#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 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
*/
Revision:	1.1
Committed:	Thu Jun 30 14:26:41 2005 UTC (21 years, 3 months ago) by root
Content type:	text/plain
Branch:	MAIN
CVS Tags:	PERL-5-8-7, HEAD
Branch point for:	PERL
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	/* cv.h
2			*
3			* Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999,
4			* 2000, 2001, 2002, 2003, 2004, by Larry Wall and others
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			*
9			*/
10
11			/* This structure must match XPVCV in B/C.pm and the beginning of XPVFM
12			* in sv.h */
13
14			struct xpvcv {
15			char * xpv_pv; /* pointer to malloced string (for prototype) */
16			STRLEN xpv_cur; /* length of xp_pv as a C string */
17			STRLEN xpv_len; /* allocated size */
18			IV xof_off; /* integer value */
19			NV xnv_nv; /* numeric value, if any */
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;
26			void (xcv_xsub) (pTHX_ CV);
27			ANY xcv_xsubany;
28			GV * xcv_gv;
29			char * xcv_file;
30			long xcv_depth; /* >= 2 indicates recursive call */
31			PADLIST * xcv_padlist;
32			CV * xcv_outside;
33			#ifdef USE_5005THREADS
34			perl_mutex *xcv_mutexp;
35			struct perl_thread xcv_owner; / current owner thread */
36			#endif /* USE_5005THREADS */
37			cv_flags_t xcv_flags;
38			U32 xcv_outside_seq; /* the COP sequence (at the point of our
39			* compilation) in the lexically enclosing
40			* sub */
41			};
42
43			/*
44			=head1 Handy Values
45
46			=for apidoc AmU\|\|Nullcv
47			Null CV pointer.
48
49			=head1 CV Manipulation Functions
50
51			=for apidoc Am\|HV\|CvSTASH\|CV cv
52			Returns the stash of the CV.
53
54			=cut
55			*/
56
57			#define Nullcv Null(CV*)
58
59			#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
60			#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start
61			#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root
62			#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_xsub
63			#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_xsubany
64			#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
65			#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
66			#ifdef USE_ITHREADS
67			# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
68			#else
69			# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
70			#endif
71			#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
72			#define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xcv_depth
73			#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
74			#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
75			#ifdef USE_5005THREADS
76			#define CvMUTEXP(sv) ((XPVCV*)SvANY(sv))->xcv_mutexp
77			#define CvOWNER(sv) ((XPVCV*)SvANY(sv))->xcv_owner
78			#endif /* USE_5005THREADS */
79			#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
80			#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
81
82			#define CVf_CLONE 0x0001 /* anon CV uses external lexicals */
83			#define CVf_CLONED 0x0002 /* a clone of one of those */
84			#define CVf_ANON 0x0004 /* CvGV() can't be trusted */
85			#define CVf_OLDSTYLE 0x0008
86			#define CVf_UNIQUE 0x0010 /* sub is only called once (eg PL_main_cv,
87			* require, eval). Not to be confused
88			* with the GVf_UNIQUE flag associated
89			* with the :unique attribute */
90			#define CVf_NODEBUG 0x0020 /* no DB::sub indirection for this CV
91			(esp. useful for special XSUBs) */
92			#define CVf_METHOD 0x0040 /* CV is explicitly marked as a method */
93			#define CVf_LOCKED 0x0080 /* CV locks itself or first arg on entry */
94			#define CVf_LVALUE 0x0100 /* CV return value can be used as lvalue */
95			#define CVf_CONST 0x0200 /* inlinable sub */
96			#define CVf_WEAKOUTSIDE 0x0400 /* CvOUTSIDE isn't ref counted */
97
98			/* This symbol for optimised communication between toke.c and op.c: */
99			#define CVf_BUILTIN_ATTRS (CVf_METHOD\|CVf_LOCKED\|CVf_LVALUE)
100
101			#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
102			#define CvCLONE_on(cv) (CvFLAGS(cv) \|= CVf_CLONE)
103			#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
104
105			#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
106			#define CvCLONED_on(cv) (CvFLAGS(cv) \|= CVf_CLONED)
107			#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
108
109			#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
110			#define CvANON_on(cv) (CvFLAGS(cv) \|= CVf_ANON)
111			#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
112
113			#ifdef PERL_XSUB_OLDSTYLE
114			#define CvOLDSTYLE(cv) (CvFLAGS(cv) & CVf_OLDSTYLE)
115			#define CvOLDSTYLE_on(cv) (CvFLAGS(cv) \|= CVf_OLDSTYLE)
116			#define CvOLDSTYLE_off(cv) (CvFLAGS(cv) &= ~CVf_OLDSTYLE)
117			#endif
118
119			#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
120			#define CvUNIQUE_on(cv) (CvFLAGS(cv) \|= CVf_UNIQUE)
121			#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
122
123			#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
124			#define CvNODEBUG_on(cv) (CvFLAGS(cv) \|= CVf_NODEBUG)
125			#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
126
127			#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
128			#define CvMETHOD_on(cv) (CvFLAGS(cv) \|= CVf_METHOD)
129			#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
130
131			#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
132			#define CvLOCKED_on(cv) (CvFLAGS(cv) \|= CVf_LOCKED)
133			#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
134
135			#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
136			#define CvLVALUE_on(cv) (CvFLAGS(cv) \|= CVf_LVALUE)
137			#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
138
139			#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
140			#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
141			#define CvEVAL_off(cv) CvUNIQUE_off(cv)
142
143			/* BEGIN\|CHECK\|INIT\|END */
144			#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
145			#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
146			#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
147
148			#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
149			#define CvCONST_on(cv) (CvFLAGS(cv) \|= CVf_CONST)
150			#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
151
152			#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
153			#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) \|= CVf_WEAKOUTSIDE)
154			#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
155
156
157			/*
158			=head1 CV reference counts and CvOUTSIDE
159
160			=for apidoc m\|bool\|CvWEAKOUTSIDE\|CV *cv
161
162			Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
163			CV (if any). Because pointers to anonymous sub prototypes are
164			stored in C<&> pad slots, it is a possible to get a circular reference,
165			with the parent pointing to the child and vice-versa. To avoid the
166			ensuing memory leak, we do not increment the reference count of the CV
167			pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
168			has a C<&> pad slot pointing back to us. In this case, we set the
169			C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
170			circumstances we should decrement the refcount of the parent when freeing
171			the child.
172
173			There is a further complication with non-closure anonymous subs (ie those
174			that do not refer to any lexicals outside that sub). In this case, the
175			anonymous prototype is shared rather than being cloned. This has the
176			consequence that the parent may be freed while there are still active
177			children, eg
178
179			BEGIN { $a = sub { eval '$x' } }
180
181			In this case, the BEGIN is freed immediately after execution since there
182			are no active references to it: the anon sub prototype has
183			C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
184			CV, so it doesn't contribute to BEGIN's refcount either. When $a is
185			executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
186			and the freed BEGIN is accessed.
187
188			To avoid this, whenever a CV and its associated pad is freed, any
189			C<&> entries in the pad are explicitly removed from the pad, and if the
190			refcount of the pointed-to anon sub is still positive, then that
191			child's C<CvOUTSIDE> is set to point to its grandparent. This will only
192			occur in the single specific case of a non-closure anon prototype
193			having one or more active references (such as C<$a> above).
194
195			One other thing to consider is that a CV may be merely undefined
196			rather than freed, eg C<undef &foo>. In this case, its refcount may
197			not have reached zero, but we still delete its pad and its C<CvROOT> etc.
198			Since various children may still have their C<CvOUTSIDE> pointing at this
199			undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
200			the chain of lexical scopes is unbroken. For example, the following
201			should print 123:
202
203			my $x = 123;
204			sub tmp { sub { eval '$x' } }
205			my $a = tmp();
206			undef &tmp;
207			print $a->();
208
209			=cut
210			*/