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a0d0e21e 1/* cv.h
79072805 2 *
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3 * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, 2000,
4 * 2001, 2002, 2003, 2004, 2005, 2006, 2007, 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 {
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14 union {
15 NV xnv_nv; /* numeric value, if any */
16 HV * xgv_stash;
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17 struct {
18 U32 xlow;
19 U32 xhigh;
20 } xpad_cop_seq; /* used by pad.c for cop_sequence */
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21 struct {
22 U32 xbm_previous; /* how many characters in string before rare? */
23 U8 xbm_flags;
24 U8 xbm_rare; /* rarest character in string */
25 } xbm_s; /* fields from PVBM */
58430790 26 } xnv_u;
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27 STRLEN xpv_cur; /* length of xp_pv as a C string */
28 STRLEN xpv_len; /* allocated size */
e4305a63 29 union {
bb172083 30 IV xivu_iv;
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31 UV xivu_uv;
32 void * xivu_p1;
bb172083 33 I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12 34 HEK * xivu_namehek;
311a25d9 35 } xiv_u;
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36 union {
37 MAGIC* xmg_magic; /* linked list of magicalness */
38 HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
39 } xmg_u;
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40 HV* xmg_stash; /* class package */
41
42 HV * xcv_stash;
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43 union {
44 OP * xcv_start;
45 ANY xcv_xsubany;
46 } xcv_start_u;
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47 union {
48 OP * xcv_root;
49 void (*xcv_xsub) (pTHX_ CV*);
50 } xcv_root_u;
8990e307 51 GV * xcv_gv;
57843af0 52 char * xcv_file;
dd2155a4 53 PADLIST * xcv_padlist;
748a9306 54 CV * xcv_outside;
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55 U32 xcv_outside_seq; /* the COP sequence (at the point of our
56 * compilation) in the lexically enclosing
57 * sub */
bb172083 58 cv_flags_t xcv_flags;
79072805 59};
748a9306 60
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61typedef struct {
62 STRLEN xpv_cur; /* length of xp_pv as a C string */
63 STRLEN xpv_len; /* allocated size */
64 union {
65 IV xivu_iv;
66 UV xivu_uv;
67 void * xivu_p1;
68 I32 xivu_i32; /* depth, >= 2 indicates recursive call */
69ecfd12 69 HEK * xivu_namehek;
c84c4652 70 } xiv_u;
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71 union {
72 MAGIC* xmg_magic; /* linked list of magicalness */
73 HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */
74 } xmg_u;
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75 HV* xmg_stash; /* class package */
76
77 HV * xcv_stash;
78 union {
79 OP * xcv_start;
80 ANY xcv_xsubany;
81 } xcv_start_u;
82 union {
83 OP * xcv_root;
84 void (*xcv_xsub) (pTHX_ CV*);
85 } xcv_root_u;
86 GV * xcv_gv;
87 char * xcv_file;
88 PADLIST * xcv_padlist;
89 CV * xcv_outside;
90 U32 xcv_outside_seq; /* the COP sequence (at the point of our
91 * compilation) in the lexically enclosing
92 * sub */
93 cv_flags_t xcv_flags;
94} xpvcv_allocated;
95
954c1994 96/*
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97=head1 Handy Values
98
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99=for apidoc AmU||Nullcv
100Null CV pointer.
101
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102=head1 CV Manipulation Functions
103
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104=for apidoc Am|HV*|CvSTASH|CV* cv
105Returns the stash of the CV.
106
107=cut
108*/
109
79072805 110#define Nullcv Null(CV*)
a5f75d66 111
79072805 112#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
bf53b3a5 113#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start
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114#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root
115#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub
bf53b3a5 116#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany
8990e307 117#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0 118#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
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119#ifdef USE_ITHREADS
120# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
121#else
122# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
123#endif
9ec2a764 124#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
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125#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
126# define CvDEPTH(sv) (*({const CV *_cv = (CV *)sv; \
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127 assert(SvTYPE(_cv) == SVt_PVCV || \
128 SvTYPE(_cv) == SVt_PVFM); \
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129 &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \
130 }))
131#else
132# define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32
133#endif
79072805 134#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306 135#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66 136#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc 137#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66 138
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139#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
140#define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */
141#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
142#define CVf_ASSERTION 0x0008 /* CV called only when asserting */
143
144#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
145#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
146#define CVf_CLONED 0x0040 /* a clone of one of those */
147#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
148#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 149 * require, eval). */
5b4563c8 150#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 151 (esp. useful for special XSUBs) */
5b4563c8 152#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291 153#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52 154
d3cea301 155/* This symbol for optimised communication between toke.c and op.c: */
06492da6 156#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION)
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157
158#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
159#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
160#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
161
162#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
163#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
164#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
165
166#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
167#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
168#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 169
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170#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
171#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
172#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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173
174#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
175#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
176#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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177
178#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
179#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
180#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
181
182#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
183#define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED)
184#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91 185
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186#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
187#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
188#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
189
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190#define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION)
191#define CvASSERTION_on(cv) (CvFLAGS(cv) |= CVf_ASSERTION)
192#define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION)
193
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194#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
195#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
196#define CvEVAL_off(cv) CvUNIQUE_off(cv)
197
3c10abe3 198/* BEGIN|CHECK|INIT|UNITCHECK|END */
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199#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
200#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
201#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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202
203#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
204#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
205#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 206
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207#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
208#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
209#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
210
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211#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
212#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
213#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
214
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215/* Flags for newXS_flags */
216#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
217
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218/*
219=head1 CV reference counts and CvOUTSIDE
220
221=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
222
223Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
224CV (if any). Because pointers to anonymous sub prototypes are
225stored in C<&> pad slots, it is a possible to get a circular reference,
226with the parent pointing to the child and vice-versa. To avoid the
227ensuing memory leak, we do not increment the reference count of the CV
228pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
229has a C<&> pad slot pointing back to us. In this case, we set the
230C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
231circumstances we should decrement the refcount of the parent when freeing
232the child.
233
eeb8d49e 234There is a further complication with non-closure anonymous subs (i.e. those
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235that do not refer to any lexicals outside that sub). In this case, the
236anonymous prototype is shared rather than being cloned. This has the
237consequence that the parent may be freed while there are still active
238children, eg
239
240 BEGIN { $a = sub { eval '$x' } }
241
242In this case, the BEGIN is freed immediately after execution since there
243are no active references to it: the anon sub prototype has
244C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
245CV, so it doesn't contribute to BEGIN's refcount either. When $a is
246executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
247and the freed BEGIN is accessed.
248
249To avoid this, whenever a CV and its associated pad is freed, any
250C<&> entries in the pad are explicitly removed from the pad, and if the
251refcount of the pointed-to anon sub is still positive, then that
252child's C<CvOUTSIDE> is set to point to its grandparent. This will only
253occur in the single specific case of a non-closure anon prototype
254having one or more active references (such as C<$a> above).
255
256One other thing to consider is that a CV may be merely undefined
257rather than freed, eg C<undef &foo>. In this case, its refcount may
258not have reached zero, but we still delete its pad and its C<CvROOT> etc.
259Since various children may still have their C<CvOUTSIDE> pointing at this
260undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
261the chain of lexical scopes is unbroken. For example, the following
262should print 123:
263
264 my $x = 123;
265 sub tmp { sub { eval '$x' } }
266 my $a = tmp();
267 undef &tmp;
268 print $a->();
269
270=cut
271*/
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272
273/*
274 * Local variables:
275 * c-indentation-style: bsd
276 * c-basic-offset: 4
277 * indent-tabs-mode: t
278 * End:
279 *
280 * ex: set ts=8 sts=4 sw=4 noet:
281 */