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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, 2001,
4 * 2002, 2003, 2004, 2005, 2006, 2007, 2008 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 {
20f4945e 14 _XPV_HEAD;
20f4945e 15 _XPVCV_COMMON;
c4648999 16 I32 xcv_depth; /* >= 2 indicates recursive call */
79072805 17};
748a9306 18
954c1994 19/*
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20=head1 Handy Values
21
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22=for apidoc AmU||Nullcv
23Null CV pointer.
24
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25(deprecated - use C<(CV *)NULL> instead)
26
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27=head1 CV Manipulation Functions
28
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29=for apidoc Am|HV*|CvSTASH|CV* cv
30Returns the stash of the CV.
31
32=cut
33*/
34
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35#ifndef PERL_CORE
36# define Nullcv Null(CV*)
37#endif
a5f75d66 38
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39#define CvSTASH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash
40#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
41#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
42#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
43#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
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44#define CvGV(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv)
45#define CvGV_set(cv,gv) Perl_cvgv_set(aTHX_ cv, gv)
8f629a87 46#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
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47#ifdef USE_ITHREADS
48# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
49#else
50# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
51#endif
9ec2a764 52#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083 53#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
8f629a87 54# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \
5129b2ca 55 assert(SvTYPE(_cvdepth) == SVt_PVCV); \
c4648999 56 &((XPVCV*)SvANY(_cvdepth))->xcv_depth; \
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57 }))
58#else
c4648999 59# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_depth
bb172083 60#endif
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61#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
62#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
63#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
64#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66 65
5b4563c8 66#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
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67#define CVf_LVALUE 0x0002 /* CV return value can be used as lvalue */
68#define CVf_CONST 0x0004 /* inlinable sub */
69#define CVf_ISXSUB 0x0008 /* CV is an XSUB, not pure perl. */
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70
71#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
72#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
73#define CVf_CLONED 0x0040 /* a clone of one of those */
cfc1e951 74#define CVf_ANON 0x0080 /* CV is not pointed to by a GV */
5b4563c8 75#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 76 * require, eval). */
5b4563c8 77#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 78 (esp. useful for special XSUBs) */
cfc1e951 79#define CVf_CVGV_RC 0x0400 /* CvGV is reference counted */
7dafbf52 80
d3cea301 81/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0 82#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE)
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83
84#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
85#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
86#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
87
88#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
89#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
90#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
91
92#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
93#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
94#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 95
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96#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
97#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
98#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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99
100#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
101#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
102#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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103
104#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
105#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
106#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
107
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108#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
109#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
110#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
111
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112#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
113#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
114#define CvEVAL_off(cv) CvUNIQUE_off(cv)
115
3c10abe3 116/* BEGIN|CHECK|INIT|UNITCHECK|END */
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117#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
118#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
119#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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120
121#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
122#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
123#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 124
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125#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
126#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
127#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
128
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129#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
130#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
131#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
132
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133#define CvCVGV_RC(cv) (CvFLAGS(cv) & CVf_CVGV_RC)
134#define CvCVGV_RC_on(cv) (CvFLAGS(cv) |= CVf_CVGV_RC)
135#define CvCVGV_RC_off(cv) (CvFLAGS(cv) &= ~CVf_CVGV_RC)
136
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137/* Flags for newXS_flags */
138#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
139
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140/*
141=head1 CV reference counts and CvOUTSIDE
142
143=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
144
145Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
146CV (if any). Because pointers to anonymous sub prototypes are
147stored in C<&> pad slots, it is a possible to get a circular reference,
148with the parent pointing to the child and vice-versa. To avoid the
149ensuing memory leak, we do not increment the reference count of the CV
150pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
151has a C<&> pad slot pointing back to us. In this case, we set the
152C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
153circumstances we should decrement the refcount of the parent when freeing
154the child.
155
eeb8d49e 156There is a further complication with non-closure anonymous subs (i.e. those
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157that do not refer to any lexicals outside that sub). In this case, the
158anonymous prototype is shared rather than being cloned. This has the
159consequence that the parent may be freed while there are still active
160children, eg
161
162 BEGIN { $a = sub { eval '$x' } }
163
164In this case, the BEGIN is freed immediately after execution since there
165are no active references to it: the anon sub prototype has
166C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
167CV, so it doesn't contribute to BEGIN's refcount either. When $a is
168executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
169and the freed BEGIN is accessed.
170
171To avoid this, whenever a CV and its associated pad is freed, any
172C<&> entries in the pad are explicitly removed from the pad, and if the
173refcount of the pointed-to anon sub is still positive, then that
174child's C<CvOUTSIDE> is set to point to its grandparent. This will only
175occur in the single specific case of a non-closure anon prototype
176having one or more active references (such as C<$a> above).
177
178One other thing to consider is that a CV may be merely undefined
179rather than freed, eg C<undef &foo>. In this case, its refcount may
180not have reached zero, but we still delete its pad and its C<CvROOT> etc.
181Since various children may still have their C<CvOUTSIDE> pointing at this
182undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
183the chain of lexical scopes is unbroken. For example, the following
184should print 123:
185
186 my $x = 123;
187 sub tmp { sub { eval '$x' } }
188 my $a = tmp();
189 undef &tmp;
190 print $a->();
191
192=cut
193*/
102d3b8a 194
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195typedef OP *(*Perl_call_checker)(pTHX_ OP *, GV *, SV *);
196
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197/*
198 * Local variables:
199 * c-indentation-style: bsd
200 * c-basic-offset: 4
201 * indent-tabs-mode: t
202 * End:
203 *
204 * ex: set ts=8 sts=4 sw=4 noet:
205 */