RE: [PATCH] compress 2.018
[p5sagit/p5-mst-13.2.git] / cv.h
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a0d0e21e 1/* cv.h
79072805 2 *
1129b882 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
79072805 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 *
79072805 9 */
10
7c60e434 11/* This structure must the beginning of XPVFM in sv.h */
44a8e56a 12
79072805 13struct xpvcv {
20f4945e 14 _XPV_HEAD;
15 _XPVMG_HEAD;
16 _XPVCV_COMMON;
79072805 17};
748a9306 18
c84c4652 19typedef struct {
20f4945e 20 _XPV_ALLOCATED_HEAD;
21 _XPVMG_HEAD;
22 _XPVCV_COMMON;
c84c4652 23} xpvcv_allocated;
24
954c1994 25/*
ccfc67b7 26=head1 Handy Values
27
954c1994 28=for apidoc AmU||Nullcv
29Null CV pointer.
30
3ae1b226 31(deprecated - use C<(CV *)NULL> instead)
32
ccfc67b7 33=head1 CV Manipulation Functions
34
954c1994 35=for apidoc Am|HV*|CvSTASH|CV* cv
36Returns the stash of the CV.
37
38=cut
39*/
40
3ae1b226 41#ifndef PERL_CORE
42# define Nullcv Null(CV*)
43#endif
a5f75d66 44
8f629a87 45#define CvSTASH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash
46#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
47#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
48#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
49#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
50#define CvGV(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv
51#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
a636914a 52#ifdef USE_ITHREADS
53# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
54#else
55# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
56#endif
9ec2a764 57#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
bb172083 58#if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN)
8f629a87 59# define CvDEPTH(sv) (*({const CV *const _cvdepth = (const CV *)sv; \
5129b2ca 60 assert(SvTYPE(_cvdepth) == SVt_PVCV); \
7948fc08 61 &((XPVCV*)SvANY(_cvdepth))->xiv_u.xivu_i32; \
bb172083 62 }))
63#else
8f629a87 64# define CvDEPTH(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xiv_u.xivu_i32
bb172083 65#endif
8f629a87 66#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
67#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
68#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
69#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66 70
5b4563c8 71#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
5b4563c8 72#define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */
5b4563c8 73
74#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
75#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
76#define CVf_CLONED 0x0040 /* a clone of one of those */
77#define CVf_ANON 0x0080 /* CvGV() can't be trusted */
78#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 79 * require, eval). */
5b4563c8 80#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 81 (esp. useful for special XSUBs) */
5b4563c8 82#define CVf_CONST 0x0400 /* inlinable sub */
f73ef291 83#define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */
7dafbf52 84
d3cea301 85/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0 86#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE)
a5f75d66 87
88#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
89#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
90#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
91
92#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
93#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
94#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
95
96#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
97#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
98#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 99
07055b4c 100#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
101#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
102#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
8ebc5c01 103
104#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
105#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
106#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
77a005ab 107
108#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
109#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
110#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
111
cd06dffe 112#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
113#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
114#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
115
1aff0e91 116#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
117#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
118#define CvEVAL_off(cv) CvUNIQUE_off(cv)
119
3c10abe3 120/* BEGIN|CHECK|INIT|UNITCHECK|END */
1aff0e91 121#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
122#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
123#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
beab0874 124
125#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
126#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
127#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 128
7dafbf52 129#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
130#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
131#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
132
d04ba589 133#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
134#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
135#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
136
77004dee 137/* Flags for newXS_flags */
138#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
139
7dafbf52 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
7dafbf52 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
195/*
196 * Local variables:
197 * c-indentation-style: bsd
198 * c-basic-offset: 4
199 * indent-tabs-mode: t
200 * End:
201 *
202 * ex: set ts=8 sts=4 sw=4 noet:
203 */