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Remove union _xivu from struct regexp - replace it with a non-union paren_names.
[perl5.git] / cv.h
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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;
79072805 16};
748a9306 17
954c1994 18/*
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19=head1 Handy Values
20
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21=for apidoc AmU||Nullcv
22Null CV pointer.
23
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24(deprecated - use C<(CV *)NULL> instead)
25
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26=head1 CV Manipulation Functions
27
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28=for apidoc Am|HV*|CvSTASH|CV* cv
29Returns the stash of the CV.
30
31=cut
32*/
33
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34#ifndef PERL_CORE
35# define Nullcv Null(CV*)
36#endif
a5f75d66 37
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38#define CvSTASH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash
39#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
40#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
41#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
42#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
43#define CvGV(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv
44#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
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45#ifdef USE_ITHREADS
46# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
47#else
48# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
49#endif
9ec2a764 50#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083 51#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
8f629a87 52# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \
5129b2ca 53 assert(SvTYPE(_cvdepth) == SVt_PVCV); \
7948fc08 54 &((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \
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55 }))
56#else
8f629a87 57# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xiv_u.xivu_i32
bb172083 58#endif
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59#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
60#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
61#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
62#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66 63
5b4563c8 64#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
5b4563c8 65#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
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66
67#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
68#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
69#define CVf_CLONED 0x0040 /* a clone of one of those */
70#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
71#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 72 * require, eval). */
5b4563c8 73#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 74 (esp. useful for special XSUBs) */
5b4563c8 75#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291 76#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52 77
d3cea301 78/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0 79#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE)
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80
81#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
82#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
83#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
84
85#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
86#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
87#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
88
89#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
90#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
91#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 92
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93#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
94#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
95#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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96
97#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
98#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
99#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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100
101#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
102#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
103#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
104
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105#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
106#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
107#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
108
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109#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
110#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
111#define CvEVAL_off(cv) CvUNIQUE_off(cv)
112
3c10abe3 113/* BEGIN|CHECK|INIT|UNITCHECK|END */
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114#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
115#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
116#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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117
118#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
119#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
120#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 121
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122#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
123#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
124#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
125
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126#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
127#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
128#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
129
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130/* Flags for newXS_flags */
131#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
132
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133/*
134=head1 CV reference counts and CvOUTSIDE
135
136=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
137
138Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
139CV (if any). Because pointers to anonymous sub prototypes are
140stored in C<&> pad slots, it is a possible to get a circular reference,
141with the parent pointing to the child and vice-versa. To avoid the
142ensuing memory leak, we do not increment the reference count of the CV
143pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
144has a C<&> pad slot pointing back to us. In this case, we set the
145C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
146circumstances we should decrement the refcount of the parent when freeing
147the child.
148
eeb8d49e 149There is a further complication with non-closure anonymous subs (i.e. those
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150that do not refer to any lexicals outside that sub). In this case, the
151anonymous prototype is shared rather than being cloned. This has the
152consequence that the parent may be freed while there are still active
153children, eg
154
155 BEGIN { $a = sub { eval '$x' } }
156
157In this case, the BEGIN is freed immediately after execution since there
158are no active references to it: the anon sub prototype has
159C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
160CV, so it doesn't contribute to BEGIN's refcount either. When $a is
161executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
162and the freed BEGIN is accessed.
163
164To avoid this, whenever a CV and its associated pad is freed, any
165C<&> entries in the pad are explicitly removed from the pad, and if the
166refcount of the pointed-to anon sub is still positive, then that
167child's C<CvOUTSIDE> is set to point to its grandparent. This will only
168occur in the single specific case of a non-closure anon prototype
169having one or more active references (such as C<$a> above).
170
171One other thing to consider is that a CV may be merely undefined
172rather than freed, eg C<undef &foo>. In this case, its refcount may
173not have reached zero, but we still delete its pad and its C<CvROOT> etc.
174Since various children may still have their C<CvOUTSIDE> pointing at this
175undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
176the chain of lexical scopes is unbroken. For example, the following
177should print 123:
178
179 my $x = 123;
180 sub tmp { sub { eval '$x' } }
181 my $a = tmp();
182 undef &tmp;
183 print $a->();
184
185=cut
186*/
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187
188/*
189 * Local variables:
190 * c-indentation-style: bsd
191 * c-basic-offset: 4
192 * indent-tabs-mode: t
193 * End:
194 *
195 * ex: set ts=8 sts=4 sw=4 noet:
196 */