This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Fix sv_dump to dump formats without the (non-existent) NVX.
[perl5.git] / cv.h
CommitLineData
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
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 */
10
7c60e434 11/* This structure must the beginning of XPVFM in sv.h */
44a8e56a 12
79072805 13struct xpvcv {
311a25d9 14 NV xnv_nv; /* numeric value, if any */
79072805
LW
15 STRLEN xpv_cur; /* length of xp_pv as a C string */
16 STRLEN xpv_len; /* allocated size */
e4305a63 17 union {
311a25d9
NC
18 IV xivu_iv; /* integer value or pv offset */
19 UV xivu_uv;
20 void * xivu_p1;
21 } xiv_u;
79072805
LW
22 MAGIC* xmg_magic; /* magic for scalar array */
23 HV* xmg_stash; /* class package */
24
25 HV * xcv_stash;
bf53b3a5
NC
26 union {
27 OP * xcv_start;
28 ANY xcv_xsubany;
29 } xcv_start_u;
d04ba589
NC
30 union {
31 OP * xcv_root;
32 void (*xcv_xsub) (pTHX_ CV*);
33 } xcv_root_u;
8990e307 34 GV * xcv_gv;
57843af0 35 char * xcv_file;
b195d487 36 long xcv_depth; /* >= 2 indicates recursive call */
dd2155a4 37 PADLIST * xcv_padlist;
748a9306 38 CV * xcv_outside;
77a005ab 39 cv_flags_t xcv_flags;
a3985cdc
DM
40 U32 xcv_outside_seq; /* the COP sequence (at the point of our
41 * compilation) in the lexically enclosing
42 * sub */
79072805 43};
748a9306 44
954c1994 45/*
ccfc67b7
JH
46=head1 Handy Values
47
954c1994
GS
48=for apidoc AmU||Nullcv
49Null CV pointer.
50
ccfc67b7
JH
51=head1 CV Manipulation Functions
52
954c1994
GS
53=for apidoc Am|HV*|CvSTASH|CV* cv
54Returns the stash of the CV.
55
56=cut
57*/
58
79072805 59#define Nullcv Null(CV*)
a5f75d66 60
79072805 61#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
bf53b3a5 62#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start
d04ba589
NC
63#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root
64#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub
bf53b3a5 65#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany
8990e307 66#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0 67#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
a636914a
RH
68#ifdef USE_ITHREADS
69# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
70#else
71# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
72#endif
9ec2a764 73#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
79072805
LW
74#define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xcv_depth
75#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306 76#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66 77#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc 78#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66 79
5b4563c8
NC
80#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
81#define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */
82#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
83#define CVf_ASSERTION 0x0008 /* CV called only when asserting */
84
85#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
86#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
87#define CVf_CLONED 0x0040 /* a clone of one of those */
88#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
89#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
6909cc55
DM
90 * require, eval). Not to be confused
91 * with the GVf_UNIQUE flag associated
92 * with the :unique attribute */
5b4563c8 93#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 94 (esp. useful for special XSUBs) */
5b4563c8
NC
95#define CVf_CONST 0x0400 /* inlinable sub */
96#define CVf_OLDSTYLE 0x0800
d04ba589 97#define CVf_ISXSUB 0x1000 /* CV is an XSUB, not pure perl. */
7dafbf52 98
d3cea301 99/* This symbol for optimised communication between toke.c and op.c: */
06492da6 100#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION)
a5f75d66
AD
101
102#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
103#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
104#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
105
106#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
107#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
108#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
109
110#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
111#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
112#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 113
67caa1fe 114#ifdef PERL_XSUB_OLDSTYLE
a5f75d66
AD
115#define CvOLDSTYLE(cv) (CvFLAGS(cv) & CVf_OLDSTYLE)
116#define CvOLDSTYLE_on(cv) (CvFLAGS(cv) |= CVf_OLDSTYLE)
117#define CvOLDSTYLE_off(cv) (CvFLAGS(cv) &= ~CVf_OLDSTYLE)
67caa1fe 118#endif
07055b4c
CS
119
120#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
121#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
122#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
8ebc5c01
PP
123
124#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
125#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
126#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
77a005ab
MB
127
128#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
129#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
130#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
131
132#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
133#define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED)
134#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91 135
cd06dffe
GS
136#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
137#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
138#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
139
06492da6
SF
140#define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION)
141#define CvASSERTION_on(cv) (CvFLAGS(cv) |= CVf_ASSERTION)
142#define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION)
143
1aff0e91
GS
144#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
145#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
146#define CvEVAL_off(cv) CvUNIQUE_off(cv)
147
bec31f9a 148/* BEGIN|CHECK|INIT|END */
1aff0e91
GS
149#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
150#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
151#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
beab0874
JT
152
153#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
154#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
155#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 156
7dafbf52
DM
157#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
158#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
159#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
160
d04ba589
NC
161#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
162#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
163#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
164
7dafbf52
DM
165/*
166=head1 CV reference counts and CvOUTSIDE
167
168=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
169
170Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
171CV (if any). Because pointers to anonymous sub prototypes are
172stored in C<&> pad slots, it is a possible to get a circular reference,
173with the parent pointing to the child and vice-versa. To avoid the
174ensuing memory leak, we do not increment the reference count of the CV
175pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
176has a C<&> pad slot pointing back to us. In this case, we set the
177C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
178circumstances we should decrement the refcount of the parent when freeing
179the child.
180
eeb8d49e 181There is a further complication with non-closure anonymous subs (i.e. those
7dafbf52
DM
182that do not refer to any lexicals outside that sub). In this case, the
183anonymous prototype is shared rather than being cloned. This has the
184consequence that the parent may be freed while there are still active
185children, eg
186
187 BEGIN { $a = sub { eval '$x' } }
188
189In this case, the BEGIN is freed immediately after execution since there
190are no active references to it: the anon sub prototype has
191C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
192CV, so it doesn't contribute to BEGIN's refcount either. When $a is
193executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
194and the freed BEGIN is accessed.
195
196To avoid this, whenever a CV and its associated pad is freed, any
197C<&> entries in the pad are explicitly removed from the pad, and if the
198refcount of the pointed-to anon sub is still positive, then that
199child's C<CvOUTSIDE> is set to point to its grandparent. This will only
200occur in the single specific case of a non-closure anon prototype
201having one or more active references (such as C<$a> above).
202
203One other thing to consider is that a CV may be merely undefined
204rather than freed, eg C<undef &foo>. In this case, its refcount may
205not have reached zero, but we still delete its pad and its C<CvROOT> etc.
206Since various children may still have their C<CvOUTSIDE> pointing at this
207undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
208the chain of lexical scopes is unbroken. For example, the following
209should print 123:
210
211 my $x = 123;
212 sub tmp { sub { eval '$x' } }
213 my $a = tmp();
214 undef &tmp;
215 print $a->();
216
217=cut
218*/
102d3b8a
NC
219
220/*
221 * Local variables:
222 * c-indentation-style: bsd
223 * c-basic-offset: 4
224 * indent-tabs-mode: t
225 * End:
226 *
227 * ex: set ts=8 sts=4 sw=4 noet:
228 */