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1 | /* cv.h |
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2 | * |
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3 | * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999, |
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4 | * 2000, 2001, 2002, 2003, 2004, 2005, 2006, 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 | |
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11 | /* This structure must the beginning of XPVFM in sv.h */ |
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12 | |
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13 | struct xpvcv { |
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14 | NV xnv_nv; /* numeric value, if any */ |
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15 | STRLEN xpv_cur; /* length of xp_pv as a C string */ |
16 | STRLEN xpv_len; /* allocated size */ |
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17 | union { |
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18 | IV xivu_iv; |
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19 | UV xivu_uv; |
20 | void * xivu_p1; |
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21 | I32 xivu_i32; /* depth, >= 2 indicates recursive call */ |
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22 | } xiv_u; |
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23 | MAGIC* xmg_magic; /* magic for scalar array */ |
24 | HV* xmg_stash; /* class package */ |
25 | |
26 | HV * xcv_stash; |
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27 | union { |
28 | OP * xcv_start; |
29 | ANY xcv_xsubany; |
30 | } xcv_start_u; |
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31 | union { |
32 | OP * xcv_root; |
33 | void (*xcv_xsub) (pTHX_ CV*); |
34 | } xcv_root_u; |
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35 | GV * xcv_gv; |
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36 | char * xcv_file; |
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37 | PADLIST * xcv_padlist; |
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38 | CV * xcv_outside; |
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39 | U32 xcv_outside_seq; /* the COP sequence (at the point of our |
40 | * compilation) in the lexically enclosing |
41 | * sub */ |
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42 | cv_flags_t xcv_flags; |
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43 | }; |
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44 | |
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45 | typedef struct { |
46 | STRLEN xpv_cur; /* length of xp_pv as a C string */ |
47 | STRLEN xpv_len; /* allocated size */ |
48 | union { |
49 | IV xivu_iv; |
50 | UV xivu_uv; |
51 | void * xivu_p1; |
52 | I32 xivu_i32; /* depth, >= 2 indicates recursive call */ |
53 | } xiv_u; |
54 | MAGIC* xmg_magic; /* magic for scalar array */ |
55 | HV* xmg_stash; /* class package */ |
56 | |
57 | HV * xcv_stash; |
58 | union { |
59 | OP * xcv_start; |
60 | ANY xcv_xsubany; |
61 | } xcv_start_u; |
62 | union { |
63 | OP * xcv_root; |
64 | void (*xcv_xsub) (pTHX_ CV*); |
65 | } xcv_root_u; |
66 | GV * xcv_gv; |
67 | char * xcv_file; |
68 | PADLIST * xcv_padlist; |
69 | CV * xcv_outside; |
70 | U32 xcv_outside_seq; /* the COP sequence (at the point of our |
71 | * compilation) in the lexically enclosing |
72 | * sub */ |
73 | cv_flags_t xcv_flags; |
74 | } xpvcv_allocated; |
75 | |
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76 | /* |
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77 | =head1 Handy Values |
78 | |
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79 | =for apidoc AmU||Nullcv |
80 | Null CV pointer. |
81 | |
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82 | =head1 CV Manipulation Functions |
83 | |
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84 | =for apidoc Am|HV*|CvSTASH|CV* cv |
85 | Returns the stash of the CV. |
86 | |
87 | =cut |
88 | */ |
89 | |
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90 | #define Nullcv Null(CV*) |
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91 | |
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92 | #define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash |
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93 | #define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start |
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94 | #define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root |
95 | #define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub |
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96 | #define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany |
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97 | #define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv |
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98 | #define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file |
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99 | #ifdef USE_ITHREADS |
100 | # define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop))) |
101 | #else |
102 | # define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop)) |
103 | #endif |
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104 | #define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv))) |
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105 | #if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN) |
106 | # define CvDEPTH(sv) (*({const CV *_cv = (CV *)sv; \ |
107 | assert(SvTYPE(_cv) == SVt_PVCV); \ |
108 | &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \ |
109 | })) |
110 | #else |
111 | # define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32 |
112 | #endif |
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113 | #define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist |
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114 | #define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside |
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115 | #define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags |
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116 | #define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq |
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117 | |
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118 | #define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ |
119 | #define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */ |
120 | #define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */ |
121 | #define CVf_ASSERTION 0x0008 /* CV called only when asserting */ |
122 | |
123 | #define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ |
124 | #define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ |
125 | #define CVf_CLONED 0x0040 /* a clone of one of those */ |
126 | #define CVf_ANON 0x0080 /* CvGV() can't be trusted */ |
127 | #define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, |
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128 | * require, eval). Not to be confused |
129 | * with the GVf_UNIQUE flag associated |
130 | * with the :unique attribute */ |
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131 | #define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV |
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132 | (esp. useful for special XSUBs) */ |
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133 | #define CVf_CONST 0x0400 /* inlinable sub */ |
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134 | #define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */ |
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135 | |
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136 | /* This symbol for optimised communication between toke.c and op.c: */ |
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137 | #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION) |
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138 | |
139 | #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) |
140 | #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) |
141 | #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) |
142 | |
143 | #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) |
144 | #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) |
145 | #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) |
146 | |
147 | #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) |
148 | #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) |
149 | #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) |
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150 | |
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151 | #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) |
152 | #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) |
153 | #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) |
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154 | |
155 | #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) |
156 | #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) |
157 | #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) |
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158 | |
159 | #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) |
160 | #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) |
161 | #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) |
162 | |
163 | #define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED) |
164 | #define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED) |
165 | #define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED) |
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166 | |
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167 | #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) |
168 | #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) |
169 | #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) |
170 | |
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171 | #define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION) |
172 | #define CvASSERTION_on(cv) (CvFLAGS(cv) |= CVf_ASSERTION) |
173 | #define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION) |
174 | |
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175 | #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) |
176 | #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) |
177 | #define CvEVAL_off(cv) CvUNIQUE_off(cv) |
178 | |
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179 | /* BEGIN|CHECK|INIT|END */ |
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180 | #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) |
181 | #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) |
182 | #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) |
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183 | |
184 | #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) |
185 | #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) |
186 | #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) |
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187 | |
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188 | #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) |
189 | #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) |
190 | #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) |
191 | |
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192 | #define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) |
193 | #define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) |
194 | #define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) |
195 | |
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196 | /* |
197 | =head1 CV reference counts and CvOUTSIDE |
198 | |
199 | =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv |
200 | |
201 | Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing |
202 | CV (if any). Because pointers to anonymous sub prototypes are |
203 | stored in C<&> pad slots, it is a possible to get a circular reference, |
204 | with the parent pointing to the child and vice-versa. To avoid the |
205 | ensuing memory leak, we do not increment the reference count of the CV |
206 | pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent |
207 | has a C<&> pad slot pointing back to us. In this case, we set the |
208 | C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what |
209 | circumstances we should decrement the refcount of the parent when freeing |
210 | the child. |
211 | |
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212 | There is a further complication with non-closure anonymous subs (i.e. those |
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213 | that do not refer to any lexicals outside that sub). In this case, the |
214 | anonymous prototype is shared rather than being cloned. This has the |
215 | consequence that the parent may be freed while there are still active |
216 | children, eg |
217 | |
218 | BEGIN { $a = sub { eval '$x' } } |
219 | |
220 | In this case, the BEGIN is freed immediately after execution since there |
221 | are no active references to it: the anon sub prototype has |
222 | C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same |
223 | CV, so it doesn't contribute to BEGIN's refcount either. When $a is |
224 | executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, |
225 | and the freed BEGIN is accessed. |
226 | |
227 | To avoid this, whenever a CV and its associated pad is freed, any |
228 | C<&> entries in the pad are explicitly removed from the pad, and if the |
229 | refcount of the pointed-to anon sub is still positive, then that |
230 | child's C<CvOUTSIDE> is set to point to its grandparent. This will only |
231 | occur in the single specific case of a non-closure anon prototype |
232 | having one or more active references (such as C<$a> above). |
233 | |
234 | One other thing to consider is that a CV may be merely undefined |
235 | rather than freed, eg C<undef &foo>. In this case, its refcount may |
236 | not have reached zero, but we still delete its pad and its C<CvROOT> etc. |
237 | Since various children may still have their C<CvOUTSIDE> pointing at this |
238 | undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that |
239 | the chain of lexical scopes is unbroken. For example, the following |
240 | should print 123: |
241 | |
242 | my $x = 123; |
243 | sub tmp { sub { eval '$x' } } |
244 | my $a = tmp(); |
245 | undef &tmp; |
246 | print $a->(); |
247 | |
248 | =cut |
249 | */ |
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250 | |
251 | /* |
252 | * Local variables: |
253 | * c-indentation-style: bsd |
254 | * c-basic-offset: 4 |
255 | * indent-tabs-mode: t |
256 | * End: |
257 | * |
258 | * ex: set ts=8 sts=4 sw=4 noet: |
259 | */ |