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[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;
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) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash)
40#define CvSTASH_set(cv,st) Perl_cvstash_set(aTHX_ cv, st)
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41#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
42#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
43#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
44#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
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45#define CvGV(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv)
46#define CvGV_set(cv,gv) Perl_cvgv_set(aTHX_ cv, gv)
8f629a87 47#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
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48#ifdef USE_ITHREADS
49# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
50#else
51# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
52#endif
9ec2a764 53#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083 54#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
8f629a87 55# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \
5129b2ca 56 assert(SvTYPE(_cvdepth) == SVt_PVCV); \
c4648999 57 &((XPVCV*)SvANY(_cvdepth))->xcv_depth; \
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58 }))
59#else
c4648999 60# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_depth
bb172083 61#endif
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62#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
63#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
64#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
65#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66 66
5b4563c8 67#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
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68#define CVf_LVALUE 0x0002 /* CV return value can be used as lvalue */
69#define CVf_CONST 0x0004 /* inlinable sub */
70#define CVf_ISXSUB 0x0008 /* CV is an XSUB, not pure perl. */
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71
72#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
73#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
74#define CVf_CLONED 0x0040 /* a clone of one of those */
cfc1e951 75#define CVf_ANON 0x0080 /* CV is not pointed to by a GV */
5b4563c8 76#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 77 * require, eval). */
5b4563c8 78#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 79 (esp. useful for special XSUBs) */
cfc1e951 80#define CVf_CVGV_RC 0x0400 /* CvGV is reference counted */
7dafbf52 81
d3cea301 82/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0 83#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE)
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84
85#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
86#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
87#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
88
89#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
90#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
91#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
92
93#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
94#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
95#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 96
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97#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
98#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
99#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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100
101#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
102#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
103#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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104
105#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
106#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
107#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
108
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109#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
110#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
111#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
112
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113#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
114#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
115#define CvEVAL_off(cv) CvUNIQUE_off(cv)
116
3c10abe3 117/* BEGIN|CHECK|INIT|UNITCHECK|END */
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118#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
119#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
120#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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121
122#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
123#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
124#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 125
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126#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
127#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
128#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
129
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130#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
131#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
132#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
133
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134#define CvCVGV_RC(cv) (CvFLAGS(cv) & CVf_CVGV_RC)
135#define CvCVGV_RC_on(cv) (CvFLAGS(cv) |= CVf_CVGV_RC)
136#define CvCVGV_RC_off(cv) (CvFLAGS(cv) &= ~CVf_CVGV_RC)
137
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138/* Flags for newXS_flags */
139#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
140
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141/*
142=head1 CV reference counts and CvOUTSIDE
143
144=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
145
146Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
147CV (if any). Because pointers to anonymous sub prototypes are
148stored in C<&> pad slots, it is a possible to get a circular reference,
149with the parent pointing to the child and vice-versa. To avoid the
150ensuing memory leak, we do not increment the reference count of the CV
151pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
152has a C<&> pad slot pointing back to us. In this case, we set the
153C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
154circumstances we should decrement the refcount of the parent when freeing
155the child.
156
eeb8d49e 157There is a further complication with non-closure anonymous subs (i.e. those
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158that do not refer to any lexicals outside that sub). In this case, the
159anonymous prototype is shared rather than being cloned. This has the
160consequence that the parent may be freed while there are still active
161children, eg
162
163 BEGIN { $a = sub { eval '$x' } }
164
165In this case, the BEGIN is freed immediately after execution since there
166are no active references to it: the anon sub prototype has
167C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
168CV, so it doesn't contribute to BEGIN's refcount either. When $a is
169executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
170and the freed BEGIN is accessed.
171
172To avoid this, whenever a CV and its associated pad is freed, any
173C<&> entries in the pad are explicitly removed from the pad, and if the
174refcount of the pointed-to anon sub is still positive, then that
175child's C<CvOUTSIDE> is set to point to its grandparent. This will only
176occur in the single specific case of a non-closure anon prototype
177having one or more active references (such as C<$a> above).
178
179One other thing to consider is that a CV may be merely undefined
180rather than freed, eg C<undef &foo>. In this case, its refcount may
181not have reached zero, but we still delete its pad and its C<CvROOT> etc.
182Since various children may still have their C<CvOUTSIDE> pointing at this
183undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
184the chain of lexical scopes is unbroken. For example, the following
185should print 123:
186
187 my $x = 123;
188 sub tmp { sub { eval '$x' } }
189 my $a = tmp();
190 undef &tmp;
191 print $a->();
192
193=cut
194*/
102d3b8a 195
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196typedef OP *(*Perl_call_checker)(pTHX_ OP *, GV *, SV *);
197
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198/*
199 * Local variables:
200 * c-indentation-style: bsd
201 * c-basic-offset: 4
202 * indent-tabs-mode: t
203 * End:
204 *
205 * ex: set ts=8 sts=4 sw=4 noet:
206 */