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Implement padcv
[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
f653aab7 11/* This structure must match the beginning of XPVFM in sv.h */
44a8e56a 12
79072805 13struct xpvcv {
20f4945e 14 _XPV_HEAD;
20f4945e 15 _XPVCV_COMMON;
79072805 16};
748a9306 17
954c1994 18/*
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19=head1 Handy Values
20
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21=for apidoc AmU||Nullcv
22Null CV pointer.
23
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24(deprecated - use C<(CV *)NULL> instead)
25
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26=head1 CV Manipulation Functions
27
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28This section documents functions to manipulate CVs which are code-values,
29or subroutines. For more information, see L<perlguts>.
30
954c1994 31=for apidoc Am|HV*|CvSTASH|CV* cv
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32Returns the stash of the CV. A stash is the symbol table hash, containing
33the package-scoped variables in the package where the subroutine was defined.
34For more information, see L<perlguts>.
954c1994 35
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36This also has a special use with XS AUTOLOAD subs.
37See L<perlguts/Autoloading with XSUBs>.
38
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39=cut
40*/
41
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42#ifndef PERL_CORE
43# define Nullcv Null(CV*)
44#endif
a5f75d66 45
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46#define CvSTASH(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_stash)
47#define CvSTASH_set(cv,st) Perl_cvstash_set(aTHX_ cv, st)
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48#define CvSTART(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_start
49#define CvROOT(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_root
50#define CvXSUB(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_root_u.xcv_xsub
51#define CvXSUBANY(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_start_u.xcv_xsubany
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52#define CvGV(sv) (0+((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_gv)
53#define CvGV_set(cv,gv) Perl_cvgv_set(aTHX_ cv, gv)
8f629a87 54#define CvFILE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_file
a636914a 55#ifdef USE_ITHREADS
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56# define CvFILE_set_from_cop(sv, cop) \
57 (CvFILE(sv) = savepv(CopFILE(cop)), CvDYNFILE_on(sv))
a636914a 58#else
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59# define CvFILE_set_from_cop(sv, cop) \
60 (CvFILE(sv) = CopFILE(cop), CvDYNFILE_off(sv))
a636914a 61#endif
9ec2a764 62#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
1afe1db1 63#define CvDEPTH(sv) (*S_CvDEPTHp((const CV *)sv))
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64#define CvPADLIST(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_padlist
65#define CvOUTSIDE(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside
66#define CvFLAGS(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_flags
67#define CvOUTSIDE_SEQ(sv) ((XPVCV*)MUTABLE_PTR(SvANY(sv)))->xcv_outside_seq
a5f75d66 68
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69/* These two are sometimes called on non-CVs */
70#define CvPROTO(sv) \
71 ( \
72 SvPOK(sv) \
73 ? SvTYPE(sv) == SVt_PVCV && CvAUTOLOAD(sv) \
74 ? SvEND(sv)+1 : SvPVX_const(sv) \
75 : NULL \
76 )
77#define CvPROTOLEN(sv) \
78 ( \
79 SvPOK(sv) \
80 ? SvTYPE(sv) == SVt_PVCV && CvAUTOLOAD(sv) \
81 ? SvLEN(sv)-SvCUR(sv)-2 \
82 : SvCUR(sv) \
83 : 0 \
84 )
85
5b4563c8 86#define CVf_METHOD 0x0001 /* CV is explicitly marked as a method */
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87#define CVf_LVALUE 0x0002 /* CV return value can be used as lvalue */
88#define CVf_CONST 0x0004 /* inlinable sub */
89#define CVf_ISXSUB 0x0008 /* CV is an XSUB, not pure perl. */
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90
91#define CVf_WEAKOUTSIDE 0x0010 /* CvOUTSIDE isn't ref counted */
92#define CVf_CLONE 0x0020 /* anon CV uses external lexicals */
93#define CVf_CLONED 0x0040 /* a clone of one of those */
cfc1e951 94#define CVf_ANON 0x0080 /* CV is not pointed to by a GV */
5b4563c8 95#define CVf_UNIQUE 0x0100 /* sub is only called once (eg PL_main_cv,
1108974d 96 * require, eval). */
5b4563c8 97#define CVf_NODEBUG 0x0200 /* no DB::sub indirection for this CV
8ebc5c01 98 (esp. useful for special XSUBs) */
cfc1e951 99#define CVf_CVGV_RC 0x0400 /* CvGV is reference counted */
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100#ifdef PERL_CORE
101# define CVf_SLABBED 0x0800 /* Holds refcount on op slab */
102#endif
bad4ae38 103#define CVf_DYNFILE 0x1000 /* The filename isn't static */
8fa6a409 104#define CVf_AUTOLOAD 0x2000 /* SvPVX contains AUTOLOADed sub name */
a0d2bbd5 105#define CVf_HASEVAL 0x4000 /* contains string eval */
7dafbf52 106
d3cea301 107/* This symbol for optimised communication between toke.c and op.c: */
e95ab0c0 108#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LVALUE)
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109
110#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
111#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
112#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
113
114#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
115#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
116#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
117
118#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
119#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
120#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 121
a2278b6a 122/* CvEVAL or CvSPECIAL */
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123#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
124#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
125#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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126
127#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
128#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
129#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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130
131#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
132#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
133#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
134
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135#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
136#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
137#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
138
a2278b6a 139/* eval or PL_main_cv */
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140#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
141#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
142#define CvEVAL_off(cv) CvUNIQUE_off(cv)
143
3c10abe3 144/* BEGIN|CHECK|INIT|UNITCHECK|END */
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145#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
146#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
147#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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148
149#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
150#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
151#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 152
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153#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
154#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
155#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
156
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157#define CvISXSUB(cv) (CvFLAGS(cv) & CVf_ISXSUB)
158#define CvISXSUB_on(cv) (CvFLAGS(cv) |= CVf_ISXSUB)
159#define CvISXSUB_off(cv) (CvFLAGS(cv) &= ~CVf_ISXSUB)
160
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161#define CvCVGV_RC(cv) (CvFLAGS(cv) & CVf_CVGV_RC)
162#define CvCVGV_RC_on(cv) (CvFLAGS(cv) |= CVf_CVGV_RC)
163#define CvCVGV_RC_off(cv) (CvFLAGS(cv) &= ~CVf_CVGV_RC)
164
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165#ifdef PERL_CORE
166# define CvSLABBED(cv) (CvFLAGS(cv) & CVf_SLABBED)
167# define CvSLABBED_on(cv) (CvFLAGS(cv) |= CVf_SLABBED)
168# define CvSLABBED_off(cv) (CvFLAGS(cv) &= ~CVf_SLABBED)
169#endif
170
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171#define CvDYNFILE(cv) (CvFLAGS(cv) & CVf_DYNFILE)
172#define CvDYNFILE_on(cv) (CvFLAGS(cv) |= CVf_DYNFILE)
173#define CvDYNFILE_off(cv) (CvFLAGS(cv) &= ~CVf_DYNFILE)
174
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175#define CvAUTOLOAD(cv) (CvFLAGS(cv) & CVf_AUTOLOAD)
176#define CvAUTOLOAD_on(cv) (CvFLAGS(cv) |= CVf_AUTOLOAD)
177#define CvAUTOLOAD_off(cv) (CvFLAGS(cv) &= ~CVf_AUTOLOAD)
178
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179#define CvHASEVAL(cv) (CvFLAGS(cv) & CVf_HASEVAL)
180#define CvHASEVAL_on(cv) (CvFLAGS(cv) |= CVf_HASEVAL)
181#define CvHASEVAL_off(cv) (CvFLAGS(cv) &= ~CVf_HASEVAL)
182
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183/* Flags for newXS_flags */
184#define XS_DYNAMIC_FILENAME 0x01 /* The filename isn't static */
185
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186/*
187=head1 CV reference counts and CvOUTSIDE
188
189=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
190
191Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
192CV (if any). Because pointers to anonymous sub prototypes are
193stored in C<&> pad slots, it is a possible to get a circular reference,
194with the parent pointing to the child and vice-versa. To avoid the
195ensuing memory leak, we do not increment the reference count of the CV
196pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
197has a C<&> pad slot pointing back to us. In this case, we set the
198C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
199circumstances we should decrement the refcount of the parent when freeing
200the child.
201
eeb8d49e 202There is a further complication with non-closure anonymous subs (i.e. those
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203that do not refer to any lexicals outside that sub). In this case, the
204anonymous prototype is shared rather than being cloned. This has the
205consequence that the parent may be freed while there are still active
206children, eg
207
208 BEGIN { $a = sub { eval '$x' } }
209
210In this case, the BEGIN is freed immediately after execution since there
211are no active references to it: the anon sub prototype has
212C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
213CV, so it doesn't contribute to BEGIN's refcount either. When $a is
214executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
215and the freed BEGIN is accessed.
216
217To avoid this, whenever a CV and its associated pad is freed, any
218C<&> entries in the pad are explicitly removed from the pad, and if the
219refcount of the pointed-to anon sub is still positive, then that
220child's C<CvOUTSIDE> is set to point to its grandparent. This will only
221occur in the single specific case of a non-closure anon prototype
222having one or more active references (such as C<$a> above).
223
224One other thing to consider is that a CV may be merely undefined
225rather than freed, eg C<undef &foo>. In this case, its refcount may
226not have reached zero, but we still delete its pad and its C<CvROOT> etc.
227Since various children may still have their C<CvOUTSIDE> pointing at this
228undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
229the chain of lexical scopes is unbroken. For example, the following
230should print 123:
231
232 my $x = 123;
233 sub tmp { sub { eval '$x' } }
234 my $a = tmp();
235 undef &tmp;
236 print $a->();
237
238=cut
239*/
102d3b8a 240
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241typedef OP *(*Perl_call_checker)(pTHX_ OP *, GV *, SV *);
242
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243/*
244 * Local variables:
245 * c-indentation-style: bsd
246 * c-basic-offset: 4
14d04a33 247 * indent-tabs-mode: nil
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248 * End:
249 *
14d04a33 250 * ex: set ts=8 sts=4 sw=4 et:
102d3b8a 251 */