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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 | union { |
24 | MAGIC* xmg_magic; /* linked list of magicalness */ |
25 | HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */ |
26 | } xmg_u; |
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27 | HV* xmg_stash; /* class package */ |
28 | |
29 | HV * xcv_stash; |
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30 | union { |
31 | OP * xcv_start; |
32 | ANY xcv_xsubany; |
33 | } xcv_start_u; |
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34 | union { |
35 | OP * xcv_root; |
36 | void (*xcv_xsub) (pTHX_ CV*); |
37 | } xcv_root_u; |
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38 | GV * xcv_gv; |
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39 | char * xcv_file; |
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40 | PADLIST * xcv_padlist; |
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41 | CV * xcv_outside; |
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42 | U32 xcv_outside_seq; /* the COP sequence (at the point of our |
43 | * compilation) in the lexically enclosing |
44 | * sub */ |
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45 | cv_flags_t xcv_flags; |
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46 | }; |
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47 | |
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48 | typedef struct { |
49 | STRLEN xpv_cur; /* length of xp_pv as a C string */ |
50 | STRLEN xpv_len; /* allocated size */ |
51 | union { |
52 | IV xivu_iv; |
53 | UV xivu_uv; |
54 | void * xivu_p1; |
55 | I32 xivu_i32; /* depth, >= 2 indicates recursive call */ |
56 | } xiv_u; |
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57 | union { |
58 | MAGIC* xmg_magic; /* linked list of magicalness */ |
59 | HV* xmg_ourstash; /* Stash for our (when SvPAD_OUR is true) */ |
60 | } xmg_u; |
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61 | HV* xmg_stash; /* class package */ |
62 | |
63 | HV * xcv_stash; |
64 | union { |
65 | OP * xcv_start; |
66 | ANY xcv_xsubany; |
67 | } xcv_start_u; |
68 | union { |
69 | OP * xcv_root; |
70 | void (*xcv_xsub) (pTHX_ CV*); |
71 | } xcv_root_u; |
72 | GV * xcv_gv; |
73 | char * xcv_file; |
74 | PADLIST * xcv_padlist; |
75 | CV * xcv_outside; |
76 | U32 xcv_outside_seq; /* the COP sequence (at the point of our |
77 | * compilation) in the lexically enclosing |
78 | * sub */ |
79 | cv_flags_t xcv_flags; |
80 | } xpvcv_allocated; |
81 | |
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82 | /* |
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83 | =head1 Handy Values |
84 | |
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85 | =for apidoc AmU||Nullcv |
86 | Null CV pointer. |
87 | |
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88 | =head1 CV Manipulation Functions |
89 | |
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90 | =for apidoc Am|HV*|CvSTASH|CV* cv |
91 | Returns the stash of the CV. |
92 | |
93 | =cut |
94 | */ |
95 | |
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96 | #define Nullcv Null(CV*) |
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97 | |
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98 | #define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash |
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99 | #define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_start |
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100 | #define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_root |
101 | #define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_root_u.xcv_xsub |
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102 | #define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_start_u.xcv_xsubany |
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103 | #define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv |
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104 | #define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file |
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105 | #ifdef USE_ITHREADS |
106 | # define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop))) |
107 | #else |
108 | # define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop)) |
109 | #endif |
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110 | #define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv))) |
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111 | #if defined(__GNUC__) && !defined(PERL_GCC_BRACE_GROUPS_FORBIDDEN) |
112 | # define CvDEPTH(sv) (*({const CV *_cv = (CV *)sv; \ |
113 | assert(SvTYPE(_cv) == SVt_PVCV); \ |
114 | &((XPVCV*)SvANY(_cv))->xiv_u.xivu_i32; \ |
115 | })) |
116 | #else |
117 | # define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xiv_u.xivu_i32 |
118 | #endif |
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119 | #define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist |
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120 | #define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside |
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121 | #define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags |
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122 | #define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq |
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123 | |
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124 | #define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */ |
125 | #define CVf_LOCKED 0x0002 /* CV locks itself or first arg on entry */ |
126 | #define CVf_LVALUE 0x0004 /* CV return value can be used as lvalue */ |
127 | #define CVf_ASSERTION 0x0008 /* CV called only when asserting */ |
128 | |
129 | #define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */ |
130 | #define CVf_CLONE 0x0020 /* anon CV uses external lexicals */ |
131 | #define CVf_CLONED 0x0040 /* a clone of one of those */ |
132 | #define CVf_ANON 0x0080 /* CvGV() can't be trusted */ |
133 | #define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv, |
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134 | * require, eval). Not to be confused |
135 | * with the GVf_UNIQUE flag associated |
136 | * with the :unique attribute */ |
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137 | #define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV |
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138 | (esp. useful for special XSUBs) */ |
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139 | #define CVf_CONST 0x0400 /* inlinable sub */ |
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140 | #define CVf_ISXSUB 0x0800 /* CV is an XSUB, not pure perl. */ |
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141 | |
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142 | /* This symbol for optimised communication between toke.c and op.c: */ |
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143 | #define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION) |
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144 | |
145 | #define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE) |
146 | #define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE) |
147 | #define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE) |
148 | |
149 | #define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED) |
150 | #define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED) |
151 | #define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED) |
152 | |
153 | #define CvANON(cv) (CvFLAGS(cv) & CVf_ANON) |
154 | #define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON) |
155 | #define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON) |
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156 | |
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157 | #define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE) |
158 | #define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE) |
159 | #define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE) |
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160 | |
161 | #define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG) |
162 | #define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG) |
163 | #define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG) |
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164 | |
165 | #define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD) |
166 | #define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD) |
167 | #define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD) |
168 | |
169 | #define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED) |
170 | #define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED) |
171 | #define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED) |
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172 | |
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173 | #define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE) |
174 | #define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE) |
175 | #define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE) |
176 | |
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177 | #define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION) |
178 | #define CvASSERTION_on(cv) (CvFLAGS(cv) |= CVf_ASSERTION) |
179 | #define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION) |
180 | |
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181 | #define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv)) |
182 | #define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv)) |
183 | #define CvEVAL_off(cv) CvUNIQUE_off(cv) |
184 | |
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185 | /* BEGIN|CHECK|INIT|END */ |
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186 | #define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv)) |
187 | #define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv)) |
188 | #define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv)) |
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189 | |
190 | #define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST) |
191 | #define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST) |
192 | #define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST) |
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193 | |
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194 | #define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE) |
195 | #define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE) |
196 | #define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE) |
197 | |
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198 | #define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB) |
199 | #define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB) |
200 | #define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB) |
201 | |
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202 | /* |
203 | =head1 CV reference counts and CvOUTSIDE |
204 | |
205 | =for apidoc m|bool|CvWEAKOUTSIDE|CV *cv |
206 | |
207 | Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing |
208 | CV (if any). Because pointers to anonymous sub prototypes are |
209 | stored in C<&> pad slots, it is a possible to get a circular reference, |
210 | with the parent pointing to the child and vice-versa. To avoid the |
211 | ensuing memory leak, we do not increment the reference count of the CV |
212 | pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent |
213 | has a C<&> pad slot pointing back to us. In this case, we set the |
214 | C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what |
215 | circumstances we should decrement the refcount of the parent when freeing |
216 | the child. |
217 | |
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218 | There is a further complication with non-closure anonymous subs (i.e. those |
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219 | that do not refer to any lexicals outside that sub). In this case, the |
220 | anonymous prototype is shared rather than being cloned. This has the |
221 | consequence that the parent may be freed while there are still active |
222 | children, eg |
223 | |
224 | BEGIN { $a = sub { eval '$x' } } |
225 | |
226 | In this case, the BEGIN is freed immediately after execution since there |
227 | are no active references to it: the anon sub prototype has |
228 | C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same |
229 | CV, so it doesn't contribute to BEGIN's refcount either. When $a is |
230 | executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed, |
231 | and the freed BEGIN is accessed. |
232 | |
233 | To avoid this, whenever a CV and its associated pad is freed, any |
234 | C<&> entries in the pad are explicitly removed from the pad, and if the |
235 | refcount of the pointed-to anon sub is still positive, then that |
236 | child's C<CvOUTSIDE> is set to point to its grandparent. This will only |
237 | occur in the single specific case of a non-closure anon prototype |
238 | having one or more active references (such as C<$a> above). |
239 | |
240 | One other thing to consider is that a CV may be merely undefined |
241 | rather than freed, eg C<undef &foo>. In this case, its refcount may |
242 | not have reached zero, but we still delete its pad and its C<CvROOT> etc. |
243 | Since various children may still have their C<CvOUTSIDE> pointing at this |
244 | undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that |
245 | the chain of lexical scopes is unbroken. For example, the following |
246 | should print 123: |
247 | |
248 | my $x = 123; |
249 | sub tmp { sub { eval '$x' } } |
250 | my $a = tmp(); |
251 | undef &tmp; |
252 | print $a->(); |
253 | |
254 | =cut |
255 | */ |
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256 | |
257 | /* |
258 | * Local variables: |
259 | * c-indentation-style: bsd |
260 | * c-basic-offset: 4 |
261 | * indent-tabs-mode: t |
262 | * End: |
263 | * |
264 | * ex: set ts=8 sts=4 sw=4 noet: |
265 | */ |