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