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a0d0e21e | 1 | /* cv.h |
79072805 | 2 | * |
bc641c27 NC |
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 | |
79072805 LW |
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 LW |
9 | */ |
10 | ||
7c60e434 | 11 | /* This structure must the beginning of XPVFM in sv.h */ |
44a8e56a | 12 | |
79072805 | 13 | struct xpvcv { |
20f4945e MHM |
14 | _XPV_HEAD; |
15 | _XPVMG_HEAD; | |
16 | _XPVCV_COMMON; | |
79072805 | 17 | }; |
748a9306 | 18 | |
c84c4652 | 19 | typedef struct { |
20f4945e MHM |
20 | _XPV_ALLOCATED_HEAD; |
21 | _XPVMG_HEAD; | |
22 | _XPVCV_COMMON; | |
c84c4652 NC |
23 | } xpvcv_allocated; |
24 | ||
954c1994 | 25 | /* |
ccfc67b7 JH |
26 | =head1 Handy Values |
27 | ||
954c1994 GS |
28 | =for apidoc AmU||Nullcv |
29 | Null CV pointer. | |
30 | ||
3ae1b226 NC |
31 | (deprecated - use C<(CV *)NULL> instead) |
32 | ||
ccfc67b7 JH |
33 | =head1 CV Manipulation Functions |
34 | ||
954c1994 GS |
35 | =for apidoc Am|HV*|CvSTASH|CV* cv |
36 | Returns the stash of the CV. | |
37 | ||
38 | =cut | |
39 | */ | |
40 | ||
3ae1b226 NC |
41 | #ifndef PERL_CORE |
42 | # define Nullcv Null(CV*) | |
43 | #endif | |
a5f75d66 | 44 | |
79072805 | 45 | #define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash |
bf53b3a5 | 46 | #define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start |
d04ba589 NC |
47 | #define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root |
48 | #define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub | |
bf53b3a5 | 49 | #define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany |
8990e307 | 50 | #define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv |
57843af0 | 51 | #define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file |
a636914a RH |
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 NC |
58 | #if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN) |
59 | # define CvDEPTH(sv) (*({const CV *_cv = (CV *)sv; \ | |
766e8246 NC |
60 | assert(SvTYPE(_cv) == SVt_PVCV || \ |
61 | SvTYPE(_cv) == SVt_PVFM); \ | |
bb172083 NC |
62 | &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \ |
63 | })) | |
64 | #else | |
65 | # define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32 | |
66 | #endif | |
79072805 | 67 | #define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist |
748a9306 | 68 | #define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside |
a5f75d66 | 69 | #define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags |
a3985cdc | 70 | #define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq |
a5f75d66 | 71 | |
5b4563c8 NC |
72 | #define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ |
73 | #define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */ | |
74 | #define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */ | |
5b4563c8 NC |
75 | |
76 | #define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ | |
77 | #define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ | |
78 | #define CVf_CLONED 0x0040 /* a clone of one of those */ | |
79 | #define CVf_ANON 0x0080 /* CvGV() can't be trusted */ | |
80 | #define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, | |
1108974d | 81 | * require, eval). */ |
5b4563c8 | 82 | #define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV |
8ebc5c01 | 83 | (esp. useful for special XSUBs) */ |
5b4563c8 | 84 | #define CVf_CONST 0x0400 /* inlinable sub */ |
f73ef291 | 85 | #define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */ |
7dafbf52 | 86 | |
d3cea301 | 87 | /* This symbol for optimised communication between toke.c and op.c: */ |
584420f0 | 88 | #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE) |
a5f75d66 AD |
89 | |
90 | #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) | |
91 | #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) | |
92 | #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) | |
93 | ||
94 | #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) | |
95 | #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) | |
96 | #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) | |
97 | ||
98 | #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) | |
99 | #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) | |
100 | #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) | |
79072805 | 101 | |
07055b4c CS |
102 | #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) |
103 | #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) | |
104 | #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) | |
8ebc5c01 | 105 | |
106 | #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) | |
107 | #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) | |
108 | #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) | |
77a005ab MB |
109 | |
110 | #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) | |
111 | #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) | |
112 | #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) | |
113 | ||
114 | #define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED) | |
115 | #define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED) | |
116 | #define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED) | |
1aff0e91 | 117 | |
cd06dffe GS |
118 | #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) |
119 | #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) | |
120 | #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) | |
121 | ||
1aff0e91 GS |
122 | #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) |
123 | #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) | |
124 | #define CvEVAL_off(cv) CvUNIQUE_off(cv) | |
125 | ||
3c10abe3 | 126 | /* BEGIN|CHECK|INIT|UNITCHECK|END */ |
1aff0e91 GS |
127 | #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) |
128 | #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) | |
129 | #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) | |
beab0874 JT |
130 | |
131 | #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) | |
132 | #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) | |
133 | #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) | |
a4f1a029 | 134 | |
7dafbf52 DM |
135 | #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) |
136 | #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) | |
137 | #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) | |
138 | ||
d04ba589 NC |
139 | #define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) |
140 | #define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) | |
141 | #define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) | |
142 | ||
77004dee NC |
143 | /* Flags for newXS_flags */ |
144 | #define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */ | |
145 | ||
7dafbf52 DM |
146 | /* |
147 | =head1 CV reference counts and CvOUTSIDE | |
148 | ||
149 | =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv | |
150 | ||
151 | Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing | |
152 | CV (if any). Because pointers to anonymous sub prototypes are | |
153 | stored in C<&> pad slots, it is a possible to get a circular reference, | |
154 | with the parent pointing to the child and vice-versa. To avoid the | |
155 | ensuing memory leak, we do not increment the reference count of the CV | |
156 | pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent | |
157 | has a C<&> pad slot pointing back to us. In this case, we set the | |
158 | C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what | |
159 | circumstances we should decrement the refcount of the parent when freeing | |
160 | the child. | |
161 | ||
eeb8d49e | 162 | There is a further complication with non-closure anonymous subs (i.e. those |
7dafbf52 DM |
163 | that do not refer to any lexicals outside that sub). In this case, the |
164 | anonymous prototype is shared rather than being cloned. This has the | |
165 | consequence that the parent may be freed while there are still active | |
166 | children, eg | |
167 | ||
168 | BEGIN { $a = sub { eval '$x' } } | |
169 | ||
170 | In this case, the BEGIN is freed immediately after execution since there | |
171 | are no active references to it: the anon sub prototype has | |
172 | C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same | |
173 | CV, so it doesn't contribute to BEGIN's refcount either. When $a is | |
174 | executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, | |
175 | and the freed BEGIN is accessed. | |
176 | ||
177 | To avoid this, whenever a CV and its associated pad is freed, any | |
178 | C<&> entries in the pad are explicitly removed from the pad, and if the | |
179 | refcount of the pointed-to anon sub is still positive, then that | |
180 | child's C<CvOUTSIDE> is set to point to its grandparent. This will only | |
181 | occur in the single specific case of a non-closure anon prototype | |
182 | having one or more active references (such as C<$a> above). | |
183 | ||
184 | One other thing to consider is that a CV may be merely undefined | |
185 | rather than freed, eg C<undef &foo>. In this case, its refcount may | |
186 | not have reached zero, but we still delete its pad and its C<CvROOT> etc. | |
187 | Since various children may still have their C<CvOUTSIDE> pointing at this | |
188 | undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that | |
189 | the chain of lexical scopes is unbroken. For example, the following | |
190 | should print 123: | |
191 | ||
192 | my $x = 123; | |
193 | sub tmp { sub { eval '$x' } } | |
194 | my $a = tmp(); | |
195 | undef &tmp; | |
196 | print $a->(); | |
197 | ||
198 | =cut | |
199 | */ | |
102d3b8a NC |
200 | |
201 | /* | |
202 | * Local variables: | |
203 | * c-indentation-style: bsd | |
204 | * c-basic-offset: 4 | |
205 | * indent-tabs-mode: t | |
206 | * End: | |
207 | * | |
208 | * ex: set ts=8 sts=4 sw=4 noet: | |
209 | */ |