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Fix precedence errors and add some cleanup in the new
[perl5.git] / cv.h
CommitLineData
a0d0e21e 1/* cv.h
79072805 2 *
4bb101f2
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3 * Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1999,
4 * 2000, 2001, 2002, 2003, 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
fd40b977 11/* This structure must match XPVCV in B/C.pm and the beginning of XPVFM
57843af0 12 * in sv.h */
44a8e56a 13
79072805 14struct xpvcv {
b84cd2cb 15 char * xpv_pv; /* pointer to malloced string (for prototype) */
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16 STRLEN xpv_cur; /* length of xp_pv as a C string */
17 STRLEN xpv_len; /* allocated size */
a0d0e21e 18 IV xof_off; /* integer value */
65202027 19 NV xnv_nv; /* numeric value, if any */
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20 MAGIC* xmg_magic; /* magic for scalar array */
21 HV* xmg_stash; /* class package */
22
23 HV * xcv_stash;
24 OP * xcv_start;
25 OP * xcv_root;
acfe0abc 26 void (*xcv_xsub) (pTHX_ CV*);
a0d0e21e 27 ANY xcv_xsubany;
8990e307 28 GV * xcv_gv;
57843af0 29 char * xcv_file;
b195d487 30 long xcv_depth; /* >= 2 indicates recursive call */
dd2155a4 31 PADLIST * xcv_padlist;
748a9306 32 CV * xcv_outside;
77a005ab 33 cv_flags_t xcv_flags;
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34 U32 xcv_outside_seq; /* the COP sequence (at the point of our
35 * compilation) in the lexically enclosing
36 * sub */
79072805 37};
748a9306 38
954c1994 39/*
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40=head1 Handy Values
41
954c1994
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42=for apidoc AmU||Nullcv
43Null CV pointer.
44
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45=head1 CV Manipulation Functions
46
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47=for apidoc Am|HV*|CvSTASH|CV* cv
48Returns the stash of the CV.
49
50=cut
51*/
52
79072805 53#define Nullcv Null(CV*)
a5f75d66 54
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55#define CvSTASH(sv) ((XPVCV*)SvANY(sv))->xcv_stash
56#define CvSTART(sv) ((XPVCV*)SvANY(sv))->xcv_start
57#define CvROOT(sv) ((XPVCV*)SvANY(sv))->xcv_root
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58#define CvXSUB(sv) ((XPVCV*)SvANY(sv))->xcv_xsub
59#define CvXSUBANY(sv) ((XPVCV*)SvANY(sv))->xcv_xsubany
8990e307 60#define CvGV(sv) ((XPVCV*)SvANY(sv))->xcv_gv
57843af0 61#define CvFILE(sv) ((XPVCV*)SvANY(sv))->xcv_file
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62#ifdef USE_ITHREADS
63# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = savepv(CopFILE(cop)))
64#else
65# define CvFILE_set_from_cop(sv, cop) (CvFILE(sv) = CopFILE(cop))
66#endif
9ec2a764 67#define CvFILEGV(sv) (gv_fetchfile(CvFILE(sv)))
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68#define CvDEPTH(sv) ((XPVCV*)SvANY(sv))->xcv_depth
69#define CvPADLIST(sv) ((XPVCV*)SvANY(sv))->xcv_padlist
748a9306 70#define CvOUTSIDE(sv) ((XPVCV*)SvANY(sv))->xcv_outside
a5f75d66 71#define CvFLAGS(sv) ((XPVCV*)SvANY(sv))->xcv_flags
a3985cdc 72#define CvOUTSIDE_SEQ(sv) ((XPVCV*)SvANY(sv))->xcv_outside_seq
a5f75d66 73
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74#define CVf_CLONE 0x0001 /* anon CV uses external lexicals */
75#define CVf_CLONED 0x0002 /* a clone of one of those */
76#define CVf_ANON 0x0004 /* CvGV() can't be trusted */
77#define CVf_OLDSTYLE 0x0008
78#define CVf_UNIQUE 0x0010 /* can't be cloned */
79#define CVf_NODEBUG 0x0020 /* no DB::sub indirection for this CV
8ebc5c01 80 (esp. useful for special XSUBs) */
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81#define CVf_METHOD 0x0040 /* CV is explicitly marked as a method */
82#define CVf_LOCKED 0x0080 /* CV locks itself or first arg on entry */
cd06dffe 83#define CVf_LVALUE 0x0100 /* CV return value can be used as lvalue */
beab0874 84#define CVf_CONST 0x0200 /* inlinable sub */
7dafbf52 85#define CVf_WEAKOUTSIDE 0x0400 /* CvOUTSIDE isn't ref counted */
06492da6 86#define CVf_ASSERTION 0x0800 /* CV called only when asserting */
7dafbf52 87
d3cea301 88/* This symbol for optimised communication between toke.c and op.c: */
06492da6 89#define CVf_BUILTIN_ATTRS (CVf_METHOD|CVf_LOCKED|CVf_LVALUE|CVf_ASSERTION)
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90
91#define CvCLONE(cv) (CvFLAGS(cv) & CVf_CLONE)
92#define CvCLONE_on(cv) (CvFLAGS(cv) |= CVf_CLONE)
93#define CvCLONE_off(cv) (CvFLAGS(cv) &= ~CVf_CLONE)
94
95#define CvCLONED(cv) (CvFLAGS(cv) & CVf_CLONED)
96#define CvCLONED_on(cv) (CvFLAGS(cv) |= CVf_CLONED)
97#define CvCLONED_off(cv) (CvFLAGS(cv) &= ~CVf_CLONED)
98
99#define CvANON(cv) (CvFLAGS(cv) & CVf_ANON)
100#define CvANON_on(cv) (CvFLAGS(cv) |= CVf_ANON)
101#define CvANON_off(cv) (CvFLAGS(cv) &= ~CVf_ANON)
79072805 102
67caa1fe 103#ifdef PERL_XSUB_OLDSTYLE
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104#define CvOLDSTYLE(cv) (CvFLAGS(cv) & CVf_OLDSTYLE)
105#define CvOLDSTYLE_on(cv) (CvFLAGS(cv) |= CVf_OLDSTYLE)
106#define CvOLDSTYLE_off(cv) (CvFLAGS(cv) &= ~CVf_OLDSTYLE)
67caa1fe 107#endif
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108
109#define CvUNIQUE(cv) (CvFLAGS(cv) & CVf_UNIQUE)
110#define CvUNIQUE_on(cv) (CvFLAGS(cv) |= CVf_UNIQUE)
111#define CvUNIQUE_off(cv) (CvFLAGS(cv) &= ~CVf_UNIQUE)
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112
113#define CvNODEBUG(cv) (CvFLAGS(cv) & CVf_NODEBUG)
114#define CvNODEBUG_on(cv) (CvFLAGS(cv) |= CVf_NODEBUG)
115#define CvNODEBUG_off(cv) (CvFLAGS(cv) &= ~CVf_NODEBUG)
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116
117#define CvMETHOD(cv) (CvFLAGS(cv) & CVf_METHOD)
118#define CvMETHOD_on(cv) (CvFLAGS(cv) |= CVf_METHOD)
119#define CvMETHOD_off(cv) (CvFLAGS(cv) &= ~CVf_METHOD)
120
121#define CvLOCKED(cv) (CvFLAGS(cv) & CVf_LOCKED)
122#define CvLOCKED_on(cv) (CvFLAGS(cv) |= CVf_LOCKED)
123#define CvLOCKED_off(cv) (CvFLAGS(cv) &= ~CVf_LOCKED)
1aff0e91 124
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125#define CvLVALUE(cv) (CvFLAGS(cv) & CVf_LVALUE)
126#define CvLVALUE_on(cv) (CvFLAGS(cv) |= CVf_LVALUE)
127#define CvLVALUE_off(cv) (CvFLAGS(cv) &= ~CVf_LVALUE)
128
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129#define CvASSERTION(cv) (CvFLAGS(cv) & CVf_ASSERTION)
130#define CvASSERTION_on(cv) (CvFLAGS(cv) |= CVf_ASSERTION)
131#define CvASSERTION_off(cv) (CvFLAGS(cv) &= ~CVf_ASSERTION)
132
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133#define CvEVAL(cv) (CvUNIQUE(cv) && !SvFAKE(cv))
134#define CvEVAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_off(cv))
135#define CvEVAL_off(cv) CvUNIQUE_off(cv)
136
bec31f9a 137/* BEGIN|CHECK|INIT|END */
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138#define CvSPECIAL(cv) (CvUNIQUE(cv) && SvFAKE(cv))
139#define CvSPECIAL_on(cv) (CvUNIQUE_on(cv),SvFAKE_on(cv))
140#define CvSPECIAL_off(cv) (CvUNIQUE_off(cv),SvFAKE_off(cv))
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141
142#define CvCONST(cv) (CvFLAGS(cv) & CVf_CONST)
143#define CvCONST_on(cv) (CvFLAGS(cv) |= CVf_CONST)
144#define CvCONST_off(cv) (CvFLAGS(cv) &= ~CVf_CONST)
a4f1a029 145
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146#define CvWEAKOUTSIDE(cv) (CvFLAGS(cv) & CVf_WEAKOUTSIDE)
147#define CvWEAKOUTSIDE_on(cv) (CvFLAGS(cv) |= CVf_WEAKOUTSIDE)
148#define CvWEAKOUTSIDE_off(cv) (CvFLAGS(cv) &= ~CVf_WEAKOUTSIDE)
149
150
151/*
152=head1 CV reference counts and CvOUTSIDE
153
154=for apidoc m|bool|CvWEAKOUTSIDE|CV *cv
155
156Each CV has a pointer, C<CvOUTSIDE()>, to its lexically enclosing
157CV (if any). Because pointers to anonymous sub prototypes are
158stored in C<&> pad slots, it is a possible to get a circular reference,
159with the parent pointing to the child and vice-versa. To avoid the
160ensuing memory leak, we do not increment the reference count of the CV
161pointed to by C<CvOUTSIDE> in the I<one specific instance> that the parent
162has a C<&> pad slot pointing back to us. In this case, we set the
163C<CvWEAKOUTSIDE> flag in the child. This allows us to determine under what
164circumstances we should decrement the refcount of the parent when freeing
165the child.
166
167There is a further complication with non-closure anonymous subs (ie those
168that do not refer to any lexicals outside that sub). In this case, the
169anonymous prototype is shared rather than being cloned. This has the
170consequence that the parent may be freed while there are still active
171children, eg
172
173 BEGIN { $a = sub { eval '$x' } }
174
175In this case, the BEGIN is freed immediately after execution since there
176are no active references to it: the anon sub prototype has
177C<CvWEAKOUTSIDE> set since it's not a closure, and $a points to the same
178CV, so it doesn't contribute to BEGIN's refcount either. When $a is
179executed, the C<eval '$x'> causes the chain of C<CvOUTSIDE>s to be followed,
180and the freed BEGIN is accessed.
181
182To avoid this, whenever a CV and its associated pad is freed, any
183C<&> entries in the pad are explicitly removed from the pad, and if the
184refcount of the pointed-to anon sub is still positive, then that
185child's C<CvOUTSIDE> is set to point to its grandparent. This will only
186occur in the single specific case of a non-closure anon prototype
187having one or more active references (such as C<$a> above).
188
189One other thing to consider is that a CV may be merely undefined
190rather than freed, eg C<undef &foo>. In this case, its refcount may
191not have reached zero, but we still delete its pad and its C<CvROOT> etc.
192Since various children may still have their C<CvOUTSIDE> pointing at this
193undefined CV, we keep its own C<CvOUTSIDE> for the time being, so that
194the chain of lexical scopes is unbroken. For example, the following
195should print 123:
196
197 my $x = 123;
198 sub tmp { sub { eval '$x' } }
199 my $a = tmp();
200 undef &tmp;
201 print $a->();
202
203=cut
204*/