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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
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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 *
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LW
9 */
10
7c60e434 11/* This structure must the beginning of XPVFM in sv.h */
44a8e56a 12
79072805 13struct xpvcv {
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14 union {
15 NV xnv_nv; /* numeric value, if any */
16 HV * xgv_stash;
17 } xnv_u;
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LW
18 STRLEN xpv_cur; /* length of xp_pv as a C string */
19 STRLEN xpv_len; /* allocated size */
e4305a63 20 union {
bb172083 21 IV xivu_iv;
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NC
22 UV xivu_uv;
23 void * xivu_p1;
bb172083 24 I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12 25 HEK * xivu_namehek;
311a25d9 26 } xiv_u;
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27 union {
28 MAGIC* xmg_magic; /* linked list of magicalness */
29 HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
30 } xmg_u;
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31 HV* xmg_stash; /* class package */
32
33 HV * xcv_stash;
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34 union {
35 OP * xcv_start;
36 ANY xcv_xsubany;
37 } xcv_start_u;
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38 union {
39 OP * xcv_root;
40 void (*xcv_xsub) (pTHX_ CV*);
41 } xcv_root_u;
8990e307 42 GV * xcv_gv;
57843af0 43 char * xcv_file;
dd2155a4 44 PADLIST * xcv_padlist;
748a9306 45 CV * xcv_outside;
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DM
46 U32 xcv_outside_seq; /* the COP sequence (at the point of our
47 * compilation) in the lexically enclosing
48 * sub */
bb172083 49 cv_flags_t xcv_flags;
79072805 50};
748a9306 51
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NC
52typedef struct {
53 STRLEN xpv_cur; /* length of xp_pv as a C string */
54 STRLEN xpv_len; /* allocated size */
55 union {
56 IV xivu_iv;
57 UV xivu_uv;
58 void * xivu_p1;
59 I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12 60 HEK * xivu_namehek;
c84c4652 61 } xiv_u;
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NC
62 union {
63 MAGIC* xmg_magic; /* linked list of magicalness */
64 HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
65 } xmg_u;
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NC
66 HV* xmg_stash; /* class package */
67
68 HV * xcv_stash;
69 union {
70 OP * xcv_start;
71 ANY xcv_xsubany;
72 } xcv_start_u;
73 union {
74 OP * xcv_root;
75 void (*xcv_xsub) (pTHX_ CV*);
76 } xcv_root_u;
77 GV * xcv_gv;
78 char * xcv_file;
79 PADLIST * xcv_padlist;
80 CV * xcv_outside;
81 U32 xcv_outside_seq; /* the COP sequence (at the point of our
82 * compilation) in the lexically enclosing
83 * sub */
84 cv_flags_t xcv_flags;
85} xpvcv_allocated;
86
954c1994 87/*
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88=head1 Handy Values
89
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90=for apidoc AmU||Nullcv
91Null CV pointer.
92
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93=head1 CV Manipulation Functions
94
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95=for apidoc Am|HV*|CvSTASH|CV* cv
96Returns the stash of the CV.
97
98=cut
99*/
100
79072805 101#define Nullcv Null(CV*)
a5f75d66 102
79072805 103#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
bf53b3a5 104#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start
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105#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root
106#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub
bf53b3a5 107#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany
8990e307 108#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0 109#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
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110#ifdef USE_ITHREADS
111# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
112#else
113# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
114#endif
9ec2a764 115#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
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116#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
117# define CvDEPTH(sv) (*({const CV *_cv = (CV *)sv; \
118 assert(SvTYPE(_cv) == SVt_PVCV); \
119 &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \
120 }))
121#else
122# define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32
123#endif
79072805 124#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306 125#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66 126#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc 127#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66 128
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129#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
130#define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */
131#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
132#define CVf_ASSERTION 0x0008 /* CV called only when asserting */
133
134#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
135#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
136#define CVf_CLONED 0x0040 /* a clone of one of those */
137#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
138#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 139 * require, eval). */
5b4563c8 140#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 141 (esp. useful for special XSUBs) */
5b4563c8 142#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291 143#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52 144
d3cea301 145/* This symbol for optimised communication between toke.c and op.c: */
06492da6 146#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION)
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147
148#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
149#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
150#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
151
152#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
153#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
154#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
155
156#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
157#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
158#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 159
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160#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
161#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
162#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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163
164#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
165#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
166#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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MB
167
168#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
169#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
170#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
171
172#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
173#define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED)
174#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91 175
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176#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
177#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
178#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
179
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180#define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION)
181#define CvASSERTION_on(cv) (CvFLAGS(cv) |= CVf_ASSERTION)
182#define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION)
183
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184#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
185#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
186#define CvEVAL_off(cv) CvUNIQUE_off(cv)
187
bec31f9a 188/* BEGIN|CHECK|INIT|END */
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189#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
190#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
191#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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JT
192
193#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
194#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
195#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 196
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197#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
198#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
199#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
200
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201#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
202#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
203#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
204
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DM
205/*
206=head1 CV reference counts and CvOUTSIDE
207
208=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
209
210Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
211CV (if any). Because pointers to anonymous sub prototypes are
212stored in C<&> pad slots, it is a possible to get a circular reference,
213with the parent pointing to the child and vice-versa. To avoid the
214ensuing memory leak, we do not increment the reference count of the CV
215pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
216has a C<&> pad slot pointing back to us. In this case, we set the
217C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
218circumstances we should decrement the refcount of the parent when freeing
219the child.
220
eeb8d49e 221There is a further complication with non-closure anonymous subs (i.e. those
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DM
222that do not refer to any lexicals outside that sub). In this case, the
223anonymous prototype is shared rather than being cloned. This has the
224consequence that the parent may be freed while there are still active
225children, eg
226
227 BEGIN { $a = sub { eval '$x' } }
228
229In this case, the BEGIN is freed immediately after execution since there
230are no active references to it: the anon sub prototype has
231C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
232CV, so it doesn't contribute to BEGIN's refcount either. When $a is
233executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
234and the freed BEGIN is accessed.
235
236To avoid this, whenever a CV and its associated pad is freed, any
237C<&> entries in the pad are explicitly removed from the pad, and if the
238refcount of the pointed-to anon sub is still positive, then that
239child's C<CvOUTSIDE> is set to point to its grandparent. This will only
240occur in the single specific case of a non-closure anon prototype
241having one or more active references (such as C<$a> above).
242
243One other thing to consider is that a CV may be merely undefined
244rather than freed, eg C<undef &foo>. In this case, its refcount may
245not have reached zero, but we still delete its pad and its C<CvROOT> etc.
246Since various children may still have their C<CvOUTSIDE> pointing at this
247undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
248the chain of lexical scopes is unbroken. For example, the following
249should print 123:
250
251 my $x = 123;
252 sub tmp { sub { eval '$x' } }
253 my $a = tmp();
254 undef &tmp;
255 print $a->();
256
257=cut
258*/
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NC
259
260/*
261 * Local variables:
262 * c-indentation-style: bsd
263 * c-basic-offset: 4
264 * indent-tabs-mode: t
265 * End:
266 *
267 * ex: set ts=8 sts=4 sw=4 noet:
268 */