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[perl5.git] / cop.h
1 /*    cop.h
2  *
3  *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
4  *    2000, 2001, 2002, 2003, 2004, 2005, 2006 by Larry Wall and others
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  *
9  * Control ops (cops) are one of the three ops OP_NEXTSTATE, OP_DBSTATE,
10  * and OP_SETSTATE that (loosely speaking) are separate statements.
11  * They hold information important for lexical state and error reporting.
12  * At run time, PL_curcop is set to point to the most recently executed cop,
13  * and thus can be used to determine our current state.
14  */
15
16 /* A jmpenv packages the state required to perform a proper non-local jump.
17  * Note that there is a start_env initialized when perl starts, and top_env
18  * points to this initially, so top_env should always be non-null.
19  *
20  * Existence of a non-null top_env->je_prev implies it is valid to call
21  * longjmp() at that runlevel (we make sure start_env.je_prev is always
22  * null to ensure this).
23  *
24  * je_mustcatch, when set at any runlevel to TRUE, means eval ops must
25  * establish a local jmpenv to handle exception traps.  Care must be taken
26  * to restore the previous value of je_mustcatch before exiting the
27  * stack frame iff JMPENV_PUSH was not called in that stack frame.
28  * GSAR 97-03-27
29  */
30
31 struct jmpenv {
32     struct jmpenv *     je_prev;
33     Sigjmp_buf          je_buf;         /* only for use if !je_throw */
34     int                 je_ret;         /* last exception thrown */
35     bool                je_mustcatch;   /* need to call longjmp()? */
36 };
37
38 typedef struct jmpenv JMPENV;
39
40 #ifdef OP_IN_REGISTER
41 #define OP_REG_TO_MEM   PL_opsave = op
42 #define OP_MEM_TO_REG   op = PL_opsave
43 #else
44 #define OP_REG_TO_MEM   NOOP
45 #define OP_MEM_TO_REG   NOOP
46 #endif
47
48 /*
49  * How to build the first jmpenv.
50  *
51  * top_env needs to be non-zero. It points to an area
52  * in which longjmp() stuff is stored, as C callstack
53  * info there at least is thread specific this has to
54  * be per-thread. Otherwise a 'die' in a thread gives
55  * that thread the C stack of last thread to do an eval {}!
56  */
57
58 #define JMPENV_BOOTSTRAP \
59     STMT_START {                                \
60         Zero(&PL_start_env, 1, JMPENV);         \
61         PL_start_env.je_ret = -1;               \
62         PL_start_env.je_mustcatch = TRUE;       \
63         PL_top_env = &PL_start_env;             \
64     } STMT_END
65
66 /*
67  *   PERL_FLEXIBLE_EXCEPTIONS
68  * 
69  * All the flexible exceptions code has been removed.
70  * See the following threads for details:
71  *
72  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2004-07/msg00378.html
73  * 
74  * Joshua's original patches (which weren't applied) and discussion:
75  * 
76  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01396.html
77  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01489.html
78  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01491.html
79  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg01608.html
80  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg02144.html
81  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1998-02/msg02998.html
82  * 
83  * Chip's reworked patch and discussion:
84  * 
85  *   http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/1999-03/msg00520.html
86  * 
87  * The flaw in these patches (which went unnoticed at the time) was
88  * that they moved some code that could potentially die() out of the
89  * region protected by the setjmp()s.  This caused exceptions within
90  * END blocks and such to not be handled by the correct setjmp().
91  * 
92  * The original patches that introduces flexible exceptions were:
93  *
94  *   http://public.activestate.com/cgi-bin/perlbrowse?patch=3386
95  *   http://public.activestate.com/cgi-bin/perlbrowse?patch=5162
96  */
97
98 #define dJMPENV         JMPENV cur_env
99
100 #define JMPENV_PUSH(v) \
101     STMT_START {                                                        \
102         DEBUG_l(Perl_deb(aTHX_ "Setting up jumplevel %p, was %p\n",     \
103                          (void*)&cur_env, (void*)PL_top_env));                  \
104         cur_env.je_prev = PL_top_env;                                   \
105         OP_REG_TO_MEM;                                                  \
106         cur_env.je_ret = PerlProc_setjmp(cur_env.je_buf, SCOPE_SAVES_SIGNAL_MASK);              \
107         OP_MEM_TO_REG;                                                  \
108         PL_top_env = &cur_env;                                          \
109         cur_env.je_mustcatch = FALSE;                                   \
110         (v) = cur_env.je_ret;                                           \
111     } STMT_END
112
113 #define JMPENV_POP \
114     STMT_START {                                                        \
115         DEBUG_l(Perl_deb(aTHX_ "popping jumplevel was %p, now %p\n",    \
116                          (void*)PL_top_env, (void*)cur_env.je_prev));                   \
117         PL_top_env = cur_env.je_prev;                                   \
118     } STMT_END
119
120 #define JMPENV_JUMP(v) \
121     STMT_START {                                                \
122         OP_REG_TO_MEM;                                          \
123         if (PL_top_env->je_prev)                                \
124             PerlProc_longjmp(PL_top_env->je_buf, (v));          \
125         if ((v) == 2)                                           \
126             PerlProc_exit(STATUS_EXIT);                         \
127         PerlIO_printf(PerlIO_stderr(), "panic: top_env\n");     \
128         PerlProc_exit(1);                                       \
129     } STMT_END
130
131 #define CATCH_GET               (PL_top_env->je_mustcatch)
132 #define CATCH_SET(v)            (PL_top_env->je_mustcatch = (v))
133
134
135
136 struct cop {
137     BASEOP
138     char *      cop_label;      /* label for this construct */
139 #ifdef USE_ITHREADS
140     char *      cop_stashpv;    /* package line was compiled in */
141     char *      cop_file;       /* file name the following line # is from */
142 #else
143     HV *        cop_stash;      /* package line was compiled in */
144     GV *        cop_filegv;     /* file the following line # is from */
145 #endif
146     U32         cop_hints;      /* hints bits from pragmata */
147     U32         cop_seq;        /* parse sequence number */
148     line_t      cop_line;       /* line # of this command */
149     /* Beware. mg.c and warnings.pl assume the type of this is STRLEN *:  */
150     STRLEN *    cop_warnings;   /* lexical warnings bitmask */
151     /* compile time state of %^H.  See the comment in op.c for how this is
152        used to recreate a hash to return from caller.  */
153     struct refcounted_he * cop_hints_hash;
154 };
155
156 #ifdef USE_ITHREADS
157 #  define CopFILE(c)            ((c)->cop_file)
158 #  define CopFILEGV(c)          (CopFILE(c) \
159                                  ? gv_fetchfile(CopFILE(c)) : NULL)
160                                  
161 #  ifdef NETWARE
162 #    define CopFILE_set(c,pv)   ((c)->cop_file = savepv(pv))
163 #  else
164 #    define CopFILE_set(c,pv)   ((c)->cop_file = savesharedpv(pv))
165 #  endif
166
167 #  define CopFILESV(c)          (CopFILE(c) \
168                                  ? GvSV(gv_fetchfile(CopFILE(c))) : NULL)
169 #  define CopFILEAV(c)          (CopFILE(c) \
170                                  ? GvAV(gv_fetchfile(CopFILE(c))) : NULL)
171 #  ifdef DEBUGGING
172 #    define CopFILEAVx(c)       (assert(CopFILE(c)), \
173                                    GvAV(gv_fetchfile(CopFILE(c))))
174 #  else
175 #    define CopFILEAVx(c)       (GvAV(gv_fetchfile(CopFILE(c))))
176 #  endif
177 #  define CopSTASHPV(c)         ((c)->cop_stashpv)
178
179 #  ifdef NETWARE
180 #    define CopSTASHPV_set(c,pv)        ((c)->cop_stashpv = ((pv) ? savepv(pv) : NULL))
181 #  else
182 #    define CopSTASHPV_set(c,pv)        ((c)->cop_stashpv = savesharedpv(pv))
183 #  endif
184
185 #  define CopSTASH(c)           (CopSTASHPV(c) \
186                                  ? gv_stashpv(CopSTASHPV(c),GV_ADD) : NULL)
187 #  define CopSTASH_set(c,hv)    CopSTASHPV_set(c, (hv) ? HvNAME_get(hv) : NULL)
188 #  define CopSTASH_eq(c,hv)     ((hv) && stashpv_hvname_match(c,hv))
189 #  ifdef NETWARE
190 #    define CopSTASH_free(c) SAVECOPSTASH_FREE(c)
191 #    define CopFILE_free(c) SAVECOPFILE_FREE(c)
192 #  else
193 #    define CopSTASH_free(c)    PerlMemShared_free(CopSTASHPV(c))
194 #    define CopFILE_free(c)     (PerlMemShared_free(CopFILE(c)),(CopFILE(c) = NULL))
195 #  endif
196 #else
197 #  define CopFILEGV(c)          ((c)->cop_filegv)
198 #  define CopFILEGV_set(c,gv)   ((c)->cop_filegv = (GV*)SvREFCNT_inc(gv))
199 #  define CopFILE_set(c,pv)     CopFILEGV_set((c), gv_fetchfile(pv))
200 #  define CopFILESV(c)          (CopFILEGV(c) ? GvSV(CopFILEGV(c)) : NULL)
201 #  define CopFILEAV(c)          (CopFILEGV(c) ? GvAV(CopFILEGV(c)) : NULL)
202 #  ifdef DEBUGGING
203 #    define CopFILEAVx(c)       (assert(CopFILEGV(c)), GvAV(CopFILEGV(c)))
204 #  else
205 #    define CopFILEAVx(c)       (GvAV(CopFILEGV(c)))
206 # endif
207 #  define CopFILE(c)            (CopFILESV(c) ? SvPVX(CopFILESV(c)) : NULL)
208 #  define CopSTASH(c)           ((c)->cop_stash)
209 #  define CopSTASH_set(c,hv)    ((c)->cop_stash = (hv))
210 #  define CopSTASHPV(c)         (CopSTASH(c) ? HvNAME_get(CopSTASH(c)) : NULL)
211    /* cop_stash is not refcounted */
212 #  define CopSTASHPV_set(c,pv)  CopSTASH_set((c), gv_stashpv(pv,GV_ADD))
213 #  define CopSTASH_eq(c,hv)     (CopSTASH(c) == (hv))
214 #  define CopSTASH_free(c)      
215 #  define CopFILE_free(c)       (SvREFCNT_dec(CopFILEGV(c)),(CopFILEGV(c) = NULL))
216
217 #endif /* USE_ITHREADS */
218
219 #define CopSTASH_ne(c,hv)       (!CopSTASH_eq(c,hv))
220 #define CopLINE(c)              ((c)->cop_line)
221 #define CopLINE_inc(c)          (++CopLINE(c))
222 #define CopLINE_dec(c)          (--CopLINE(c))
223 #define CopLINE_set(c,l)        (CopLINE(c) = (l))
224
225 /* OutCopFILE() is CopFILE for output (caller, die, warn, etc.) */
226 #ifdef MACOS_TRADITIONAL
227 #  define OutCopFILE(c) MacPerl_MPWFileName(CopFILE(c))
228 #else
229 #  define OutCopFILE(c) CopFILE(c)
230 #endif
231
232 /* If $[ is non-zero, it's stored in cop_hints under the key "$[", and
233    HINT_ARYBASE is set to indicate this.
234    Setting it is ineficient due to the need to create 2 mortal SVs, but as
235    using $[ is highly discouraged, no sane Perl code will be using it.  */
236 #define CopARYBASE_get(c)       \
237         ((CopHINTS_get(c) & HINT_ARYBASE)                               \
238          ? SvIV(Perl_refcounted_he_fetch(aTHX_ (c)->cop_hints_hash, 0,  \
239                                          "$[", 2, 0, 0))                \
240          : 0)
241 #define CopARYBASE_set(c, b) STMT_START { \
242         if (b || ((c)->cop_hints & HINT_ARYBASE)) {                     \
243             (c)->cop_hints |= HINT_ARYBASE;                             \
244             if ((c) == &PL_compiling)                                   \
245                 PL_hints |= HINT_LOCALIZE_HH | HINT_ARYBASE;            \
246             (c)->cop_hints_hash                                         \
247                = Perl_refcounted_he_new(aTHX_ (c)->cop_hints_hash,      \
248                                         sv_2mortal(newSVpvs("$[")),     \
249                                         sv_2mortal(newSViv(b)));        \
250         }                                                               \
251     } STMT_END
252
253 /* FIXME NATIVE_HINTS if this is changed from op_private (see perl.h)  */
254 #define CopHINTS_get(c)         ((c)->cop_hints + 0)
255 #define CopHINTS_set(c, h)      STMT_START {                            \
256                                     (c)->cop_hints = (h);               \
257                                 } STMT_END
258
259 /*
260  * Here we have some enormously heavy (or at least ponderous) wizardry.
261  */
262
263 /* subroutine context */
264 struct block_sub {
265     CV *        cv;
266     GV *        gv;
267     GV *        dfoutgv;
268     AV *        savearray;
269     AV *        argarray;
270     I32         olddepth;
271     U8          hasargs;
272     U8          lval;           /* XXX merge lval and hasargs? */
273     PAD         *oldcomppad;
274     OP *        retop;  /* op to execute on exit from sub */
275 };
276
277 /* base for the next two macros. Don't use directly.
278  * Note that the refcnt of the cv is incremented twice;  The CX one is
279  * decremented by LEAVESUB, the other by LEAVE. */
280
281 #define PUSHSUB_BASE(cx)                                                \
282         cx->blk_sub.cv = cv;                                            \
283         cx->blk_sub.olddepth = CvDEPTH(cv);                             \
284         cx->blk_sub.hasargs = hasargs;                                  \
285         cx->blk_sub.retop = NULL;                                       \
286         if (!CvDEPTH(cv)) {                                             \
287             SvREFCNT_inc_simple_void_NN(cv);                            \
288             SvREFCNT_inc_simple_void_NN(cv);                            \
289             SAVEFREESV(cv);                                             \
290         }
291
292
293 #define PUSHSUB(cx)                                                     \
294         PUSHSUB_BASE(cx)                                                \
295         cx->blk_sub.lval = PL_op->op_private &                          \
296                               (OPpLVAL_INTRO|OPpENTERSUB_INARGS);
297
298 /* variant for use by OP_DBSTATE, where op_private holds hint bits */
299 #define PUSHSUB_DB(cx)                                                  \
300         PUSHSUB_BASE(cx)                                                \
301         cx->blk_sub.lval = 0;
302
303
304 #define PUSHFORMAT(cx)                                                  \
305         cx->blk_sub.cv = cv;                                            \
306         cx->blk_sub.gv = gv;                                            \
307         cx->blk_sub.retop = NULL;                                       \
308         cx->blk_sub.hasargs = 0;                                        \
309         cx->blk_sub.dfoutgv = PL_defoutgv;                              \
310         SvREFCNT_inc_void(cx->blk_sub.dfoutgv)
311
312 #define POP_SAVEARRAY()                                         \
313     STMT_START {                                                        \
314         SvREFCNT_dec(GvAV(PL_defgv));                                   \
315         GvAV(PL_defgv) = cx->blk_sub.savearray;                         \
316     } STMT_END
317
318 /* junk in @_ spells trouble when cloning CVs and in pp_caller(), so don't
319  * leave any (a fast av_clear(ary), basically) */
320 #define CLEAR_ARGARRAY(ary) \
321     STMT_START {                                                        \
322         AvMAX(ary) += AvARRAY(ary) - AvALLOC(ary);                      \
323         SvPV_set(ary, (char*)AvALLOC(ary));                             \
324         AvFILLp(ary) = -1;                                              \
325     } STMT_END
326
327 #define POPSUB(cx,sv)                                                   \
328     STMT_START {                                                        \
329         if (cx->blk_sub.hasargs) {                                      \
330             POP_SAVEARRAY();                                            \
331             /* abandon @_ if it got reified */                          \
332             if (AvREAL(cx->blk_sub.argarray)) {                         \
333                 const SSize_t fill = AvFILLp(cx->blk_sub.argarray);     \
334                 SvREFCNT_dec(cx->blk_sub.argarray);                     \
335                 cx->blk_sub.argarray = newAV();                         \
336                 av_extend(cx->blk_sub.argarray, fill);                  \
337                 AvREIFY_only(cx->blk_sub.argarray);                     \
338                 CX_CURPAD_SV(cx->blk_sub, 0) = (SV*)cx->blk_sub.argarray;       \
339             }                                                           \
340             else {                                                      \
341                 CLEAR_ARGARRAY(cx->blk_sub.argarray);                   \
342             }                                                           \
343         }                                                               \
344         sv = (SV*)cx->blk_sub.cv;                                       \
345         if (sv && (CvDEPTH((CV*)sv) = cx->blk_sub.olddepth))            \
346             sv = NULL;                                          \
347     } STMT_END
348
349 #define LEAVESUB(sv)                                                    \
350     STMT_START {                                                        \
351         if (sv)                                                         \
352             SvREFCNT_dec(sv);                                           \
353     } STMT_END
354
355 #define POPFORMAT(cx)                                                   \
356         setdefout(cx->blk_sub.dfoutgv);                                 \
357         SvREFCNT_dec(cx->blk_sub.dfoutgv);
358
359 /* eval context */
360 struct block_eval {
361     I32         old_in_eval;
362     I32         old_op_type;
363     SV *        old_namesv;
364     OP *        old_eval_root;
365     SV *        cur_text;
366     CV *        cv;
367     OP *        retop;  /* op to execute on exit from eval */
368     JMPENV *    cur_top_env; /* value of PL_top_env when eval CX created */
369 };
370
371 #define PUSHEVAL(cx,n,fgv)                                              \
372     STMT_START {                                                        \
373         cx->blk_eval.old_in_eval = PL_in_eval;                          \
374         cx->blk_eval.old_op_type = PL_op->op_type;                      \
375         cx->blk_eval.old_namesv = (n ? newSVpv(n,0) : NULL);            \
376         cx->blk_eval.old_eval_root = PL_eval_root;                      \
377         cx->blk_eval.cur_text = PL_linestr;                             \
378         cx->blk_eval.cv = NULL; /* set by doeval(), as applicable */    \
379         cx->blk_eval.retop = NULL;                                      \
380         cx->blk_eval.cur_top_env = PL_top_env;                          \
381     } STMT_END
382
383 #define POPEVAL(cx)                                                     \
384     STMT_START {                                                        \
385         PL_in_eval = cx->blk_eval.old_in_eval;                          \
386         optype = cx->blk_eval.old_op_type;                              \
387         PL_eval_root = cx->blk_eval.old_eval_root;                      \
388         if (cx->blk_eval.old_namesv)                                    \
389             sv_2mortal(cx->blk_eval.old_namesv);                        \
390     } STMT_END
391
392 /* loop context */
393 struct block_loop {
394     char *      label;
395     I32         resetsp;
396     OP *        redo_op;
397     OP *        next_op;
398     OP *        last_op;
399 #ifdef USE_ITHREADS
400     void *      iterdata;
401     PAD         *oldcomppad;
402 #else
403     SV **       itervar;
404 #endif
405     SV *        itersave;
406     SV *        iterlval;
407     AV *        iterary;
408     IV          iterix;
409     IV          itermax;
410 };
411
412 #ifdef USE_ITHREADS
413 #  define CxITERVAR(c)                                                  \
414         ((c)->blk_loop.iterdata                                         \
415          ? (CxPADLOOP(cx)                                               \
416             ? &CX_CURPAD_SV( (c)->blk_loop,                             \
417                     INT2PTR(PADOFFSET, (c)->blk_loop.iterdata))         \
418             : &GvSV((GV*)(c)->blk_loop.iterdata))                       \
419          : (SV**)NULL)
420 #  define CX_ITERDATA_SET(cx,idata)                                     \
421         CX_CURPAD_SAVE(cx->blk_loop);                                   \
422         if ((cx->blk_loop.iterdata = (idata)))                          \
423             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));       \
424         else                                                            \
425             cx->blk_loop.itersave = NULL;
426 #else
427 #  define CxITERVAR(c)          ((c)->blk_loop.itervar)
428 #  define CX_ITERDATA_SET(cx,ivar)                                      \
429         if ((cx->blk_loop.itervar = (SV**)(ivar)))                      \
430             cx->blk_loop.itersave = SvREFCNT_inc(*CxITERVAR(cx));       \
431         else                                                            \
432             cx->blk_loop.itersave = NULL;
433 #endif
434
435 #define PUSHLOOP(cx, dat, s)                                            \
436         cx->blk_loop.label = PL_curcop->cop_label;                      \
437         cx->blk_loop.resetsp = s - PL_stack_base;                       \
438         cx->blk_loop.redo_op = cLOOP->op_redoop;                        \
439         cx->blk_loop.next_op = cLOOP->op_nextop;                        \
440         cx->blk_loop.last_op = cLOOP->op_lastop;                        \
441         cx->blk_loop.iterlval = NULL;                                   \
442         cx->blk_loop.iterary = NULL;                                    \
443         cx->blk_loop.iterix = -1;                                       \
444         CX_ITERDATA_SET(cx,dat);
445
446 #define POPLOOP(cx)                                                     \
447         SvREFCNT_dec(cx->blk_loop.iterlval);                            \
448         if (CxITERVAR(cx)) {                                            \
449             if (SvPADMY(cx->blk_loop.itersave)) {                       \
450                 SV ** const s_v_p = CxITERVAR(cx);                      \
451                 sv_2mortal(*s_v_p);                                     \
452                 *s_v_p = cx->blk_loop.itersave;                         \
453             }                                                           \
454             else {                                                      \
455                 SvREFCNT_dec(cx->blk_loop.itersave);                    \
456             }                                                           \
457         }                                                               \
458         if (cx->blk_loop.iterary && cx->blk_loop.iterary != PL_curstack)\
459             SvREFCNT_dec(cx->blk_loop.iterary);
460
461 /* given/when context */
462 struct block_givwhen {
463         OP *leave_op;
464 };
465
466 #define PUSHGIVEN(cx)                                                   \
467         cx->blk_givwhen.leave_op = cLOGOP->op_other;
468
469 #define PUSHWHEN PUSHGIVEN
470
471 /* context common to subroutines, evals and loops */
472 struct block {
473     I32         blku_oldsp;     /* stack pointer to copy stuff down to */
474     COP *       blku_oldcop;    /* old curcop pointer */
475     I32         blku_oldmarksp; /* mark stack index */
476     I32         blku_oldscopesp;        /* scope stack index */
477     PMOP *      blku_oldpm;     /* values of pattern match vars */
478     U8          blku_gimme;     /* is this block running in list context? */
479
480     union {
481         struct block_sub        blku_sub;
482         struct block_eval       blku_eval;
483         struct block_loop       blku_loop;
484         struct block_givwhen    blku_givwhen;
485     } blk_u;
486 };
487 #define blk_oldsp       cx_u.cx_blk.blku_oldsp
488 #define blk_oldcop      cx_u.cx_blk.blku_oldcop
489 #define blk_oldmarksp   cx_u.cx_blk.blku_oldmarksp
490 #define blk_oldscopesp  cx_u.cx_blk.blku_oldscopesp
491 #define blk_oldpm       cx_u.cx_blk.blku_oldpm
492 #define blk_gimme       cx_u.cx_blk.blku_gimme
493 #define blk_sub         cx_u.cx_blk.blk_u.blku_sub
494 #define blk_eval        cx_u.cx_blk.blk_u.blku_eval
495 #define blk_loop        cx_u.cx_blk.blk_u.blku_loop
496 #define blk_givwhen     cx_u.cx_blk.blk_u.blku_givwhen
497
498 /* Enter a block. */
499 #define PUSHBLOCK(cx,t,sp) CXINC, cx = &cxstack[cxstack_ix],            \
500         cx->cx_type             = t,                                    \
501         cx->blk_oldsp           = sp - PL_stack_base,                   \
502         cx->blk_oldcop          = PL_curcop,                            \
503         cx->blk_oldmarksp       = PL_markstack_ptr - PL_markstack,      \
504         cx->blk_oldscopesp      = PL_scopestack_ix,                     \
505         cx->blk_oldpm           = PL_curpm,                             \
506         cx->blk_gimme           = (U8)gimme;                            \
507         DEBUG_l( PerlIO_printf(Perl_debug_log, "Entering block %ld, type %s\n", \
508                     (long)cxstack_ix, PL_block_type[CxTYPE(cx)]); )
509
510 /* Exit a block (RETURN and LAST). */
511 #define POPBLOCK(cx,pm) cx = &cxstack[cxstack_ix--],                    \
512         newsp            = PL_stack_base + cx->blk_oldsp,               \
513         PL_curcop        = cx->blk_oldcop,                              \
514         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
515         PL_scopestack_ix = cx->blk_oldscopesp,                          \
516         pm               = cx->blk_oldpm,                               \
517         gimme            = cx->blk_gimme;                               \
518         DEBUG_SCOPE("POPBLOCK");                                        \
519         DEBUG_l( PerlIO_printf(Perl_debug_log, "Leaving block %ld, type %s\n",          \
520                     (long)cxstack_ix+1,PL_block_type[CxTYPE(cx)]); )
521
522 /* Continue a block elsewhere (NEXT and REDO). */
523 #define TOPBLOCK(cx) cx  = &cxstack[cxstack_ix],                        \
524         PL_stack_sp      = PL_stack_base + cx->blk_oldsp,               \
525         PL_markstack_ptr = PL_markstack + cx->blk_oldmarksp,            \
526         PL_scopestack_ix = cx->blk_oldscopesp,                          \
527         PL_curpm         = cx->blk_oldpm;                               \
528         DEBUG_SCOPE("TOPBLOCK");
529
530 /* substitution context */
531 struct subst {
532     I32         sbu_iters;
533     I32         sbu_maxiters;
534     I32         sbu_rflags;
535     I32         sbu_oldsave;
536     bool        sbu_once;
537     bool        sbu_rxtainted;
538     char *      sbu_orig;
539     SV *        sbu_dstr;
540     SV *        sbu_targ;
541     char *      sbu_s;
542     char *      sbu_m;
543     char *      sbu_strend;
544     void *      sbu_rxres;
545     REGEXP *    sbu_rx;
546 };
547 #define sb_iters        cx_u.cx_subst.sbu_iters
548 #define sb_maxiters     cx_u.cx_subst.sbu_maxiters
549 #define sb_rflags       cx_u.cx_subst.sbu_rflags
550 #define sb_oldsave      cx_u.cx_subst.sbu_oldsave
551 #define sb_once         cx_u.cx_subst.sbu_once
552 #define sb_rxtainted    cx_u.cx_subst.sbu_rxtainted
553 #define sb_orig         cx_u.cx_subst.sbu_orig
554 #define sb_dstr         cx_u.cx_subst.sbu_dstr
555 #define sb_targ         cx_u.cx_subst.sbu_targ
556 #define sb_s            cx_u.cx_subst.sbu_s
557 #define sb_m            cx_u.cx_subst.sbu_m
558 #define sb_strend       cx_u.cx_subst.sbu_strend
559 #define sb_rxres        cx_u.cx_subst.sbu_rxres
560 #define sb_rx           cx_u.cx_subst.sbu_rx
561
562 #define PUSHSUBST(cx) CXINC, cx = &cxstack[cxstack_ix],                 \
563         cx->sb_iters            = iters,                                \
564         cx->sb_maxiters         = maxiters,                             \
565         cx->sb_rflags           = r_flags,                              \
566         cx->sb_oldsave          = oldsave,                              \
567         cx->sb_once             = once,                                 \
568         cx->sb_rxtainted        = rxtainted,                            \
569         cx->sb_orig             = orig,                                 \
570         cx->sb_dstr             = dstr,                                 \
571         cx->sb_targ             = targ,                                 \
572         cx->sb_s                = s,                                    \
573         cx->sb_m                = m,                                    \
574         cx->sb_strend           = strend,                               \
575         cx->sb_rxres            = NULL,                                 \
576         cx->sb_rx               = rx,                                   \
577         cx->cx_type             = CXt_SUBST;                            \
578         rxres_save(&cx->sb_rxres, rx);                                  \
579         (void)ReREFCNT_inc(rx)
580
581 #define POPSUBST(cx) cx = &cxstack[cxstack_ix--];                       \
582         rxres_free(&cx->sb_rxres);                                      \
583         ReREFCNT_dec(cx->sb_rx)
584
585 struct context {
586     U32         cx_type;        /* what kind of context this is */
587     union {
588         struct block    cx_blk;
589         struct subst    cx_subst;
590     } cx_u;
591 };
592
593 #define CXTYPEMASK      0xff
594 #define CXt_NULL        0
595 #define CXt_SUB         1
596 #define CXt_EVAL        2
597 #define CXt_LOOP        3
598 #define CXt_SUBST       4
599 #define CXt_BLOCK       5
600 #define CXt_FORMAT      6
601 #define CXt_GIVEN       7
602 #define CXt_WHEN        8
603
604 /* private flags for CXt_SUB and CXt_NULL */
605 #define CXp_MULTICALL   0x00000400      /* part of a multicall (so don't
606                                            tear down context on exit). */ 
607
608 /* private flags for CXt_EVAL */
609 #define CXp_REAL        0x00000100      /* truly eval'', not a lookalike */
610 #define CXp_TRYBLOCK    0x00000200      /* eval{}, not eval'' or similar */
611
612 /* private flags for CXt_LOOP */
613 #define CXp_FOREACH     0x00000200      /* a foreach loop */
614 #define CXp_FOR_DEF     0x00000400      /* foreach using $_ */
615 #ifdef USE_ITHREADS
616 #  define CXp_PADVAR    0x00000100      /* itervar lives on pad, iterdata
617                                            has pad offset; if not set,
618                                            iterdata holds GV* */
619 #  define CxPADLOOP(c)  (((c)->cx_type & (CXt_LOOP|CXp_PADVAR))         \
620                          == (CXt_LOOP|CXp_PADVAR))
621 #endif
622
623 #define CxTYPE(c)       ((c)->cx_type & CXTYPEMASK)
624 #define CxMULTICALL(c)  (((c)->cx_type & CXp_MULTICALL)                 \
625                          == CXp_MULTICALL)
626 #define CxREALEVAL(c)   (((c)->cx_type & (CXt_EVAL|CXp_REAL))           \
627                          == (CXt_EVAL|CXp_REAL))
628 #define CxTRYBLOCK(c)   (((c)->cx_type & (CXt_EVAL|CXp_TRYBLOCK))       \
629                          == (CXt_EVAL|CXp_TRYBLOCK))
630 #define CxFOREACH(c)    (((c)->cx_type & (CXt_LOOP|CXp_FOREACH))        \
631                          == (CXt_LOOP|CXp_FOREACH))
632 #define CxFOREACHDEF(c) (((c)->cx_type & (CXt_LOOP|CXp_FOREACH|CXp_FOR_DEF))\
633                          == (CXt_LOOP|CXp_FOREACH|CXp_FOR_DEF))
634
635 #define CXINC (cxstack_ix < cxstack_max ? ++cxstack_ix : (cxstack_ix = cxinc()))
636
637 /* 
638 =head1 "Gimme" Values
639 */
640
641 /*
642 =for apidoc AmU||G_SCALAR
643 Used to indicate scalar context.  See C<GIMME_V>, C<GIMME>, and
644 L<perlcall>.
645
646 =for apidoc AmU||G_ARRAY
647 Used to indicate list context.  See C<GIMME_V>, C<GIMME> and
648 L<perlcall>.
649
650 =for apidoc AmU||G_VOID
651 Used to indicate void context.  See C<GIMME_V> and L<perlcall>.
652
653 =for apidoc AmU||G_DISCARD
654 Indicates that arguments returned from a callback should be discarded.  See
655 L<perlcall>.
656
657 =for apidoc AmU||G_EVAL
658
659 Used to force a Perl C<eval> wrapper around a callback.  See
660 L<perlcall>.
661
662 =for apidoc AmU||G_NOARGS
663
664 Indicates that no arguments are being sent to a callback.  See
665 L<perlcall>.
666
667 =cut
668 */
669
670 #define G_SCALAR        0
671 #define G_ARRAY         1
672 #define G_VOID          128     /* skip this bit when adding flags below */
673
674 /* extra flags for Perl_call_* routines */
675 #define G_DISCARD       2       /* Call FREETMPS. */
676 #define G_EVAL          4       /* Assume eval {} around subroutine call. */
677 #define G_NOARGS        8       /* Don't construct a @_ array. */
678 #define G_KEEPERR      16       /* Append errors to $@, don't overwrite it */
679 #define G_NODEBUG      32       /* Disable debugging at toplevel.  */
680 #define G_METHOD       64       /* Calling method. */
681 #define G_FAKINGEVAL  256       /* Faking en eval context for call_sv or
682                                    fold_constants. */
683
684 /* flag bits for PL_in_eval */
685 #define EVAL_NULL       0       /* not in an eval */
686 #define EVAL_INEVAL     1       /* some enclosing scope is an eval */
687 #define EVAL_WARNONLY   2       /* used by yywarn() when calling yyerror() */
688 #define EVAL_KEEPERR    4       /* set by Perl_call_sv if G_KEEPERR */
689 #define EVAL_INREQUIRE  8       /* The code is being required. */
690
691 /* Support for switching (stack and block) contexts.
692  * This ensures magic doesn't invalidate local stack and cx pointers.
693  */
694
695 #define PERLSI_UNKNOWN          -1
696 #define PERLSI_UNDEF            0
697 #define PERLSI_MAIN             1
698 #define PERLSI_MAGIC            2
699 #define PERLSI_SORT             3
700 #define PERLSI_SIGNAL           4
701 #define PERLSI_OVERLOAD         5
702 #define PERLSI_DESTROY          6
703 #define PERLSI_WARNHOOK         7
704 #define PERLSI_DIEHOOK          8
705 #define PERLSI_REQUIRE          9
706
707 struct stackinfo {
708     AV *                si_stack;       /* stack for current runlevel */
709     PERL_CONTEXT *      si_cxstack;     /* context stack for runlevel */
710     I32                 si_cxix;        /* current context index */
711     I32                 si_cxmax;       /* maximum allocated index */
712     I32                 si_type;        /* type of runlevel */
713     struct stackinfo *  si_prev;
714     struct stackinfo *  si_next;
715     I32                 si_markoff;     /* offset where markstack begins for us.
716                                          * currently used only with DEBUGGING,
717                                          * but not #ifdef-ed for bincompat */
718 };
719
720 typedef struct stackinfo PERL_SI;
721
722 #define cxstack         (PL_curstackinfo->si_cxstack)
723 #define cxstack_ix      (PL_curstackinfo->si_cxix)
724 #define cxstack_max     (PL_curstackinfo->si_cxmax)
725
726 #ifdef DEBUGGING
727 #  define       SET_MARK_OFFSET \
728     PL_curstackinfo->si_markoff = PL_markstack_ptr - PL_markstack
729 #else
730 #  define       SET_MARK_OFFSET NOOP
731 #endif
732
733 #define PUSHSTACKi(type) \
734     STMT_START {                                                        \
735         PERL_SI *next = PL_curstackinfo->si_next;                       \
736         if (!next) {                                                    \
737             next = new_stackinfo(32, 2048/sizeof(PERL_CONTEXT) - 1);    \
738             next->si_prev = PL_curstackinfo;                            \
739             PL_curstackinfo->si_next = next;                            \
740         }                                                               \
741         next->si_type = type;                                           \
742         next->si_cxix = -1;                                             \
743         AvFILLp(next->si_stack) = 0;                                    \
744         SWITCHSTACK(PL_curstack,next->si_stack);                        \
745         PL_curstackinfo = next;                                         \
746         SET_MARK_OFFSET;                                                \
747     } STMT_END
748
749 #define PUSHSTACK PUSHSTACKi(PERLSI_UNKNOWN)
750
751 /* POPSTACK works with PL_stack_sp, so it may need to be bracketed by
752  * PUTBACK/SPAGAIN to flush/refresh any local SP that may be active */
753 #define POPSTACK \
754     STMT_START {                                                        \
755         dSP;                                                            \
756         PERL_SI * const prev = PL_curstackinfo->si_prev;                \
757         if (!prev) {                                                    \
758             PerlIO_printf(Perl_error_log, "panic: POPSTACK\n");         \
759             my_exit(1);                                                 \
760         }                                                               \
761         SWITCHSTACK(PL_curstack,prev->si_stack);                        \
762         /* don't free prev here, free them all at the END{} */          \
763         PL_curstackinfo = prev;                                         \
764     } STMT_END
765
766 #define POPSTACK_TO(s) \
767     STMT_START {                                                        \
768         while (PL_curstack != s) {                                      \
769             dounwind(-1);                                               \
770             POPSTACK;                                                   \
771         }                                                               \
772     } STMT_END
773
774 #define IN_PERL_COMPILETIME     (PL_curcop == &PL_compiling)
775 #define IN_PERL_RUNTIME         (PL_curcop != &PL_compiling)
776
777 /*
778 =head1 Multicall Functions
779
780 =for apidoc Ams||dMULTICALL
781 Declare local variables for a multicall. See L<perlcall/Lightweight Callbacks>.
782
783 =for apidoc Ams||PUSH_MULTICALL
784 Opening bracket for a lightweight callback.
785 See L<perlcall/Lightweight Callbacks>.
786
787 =for apidoc Ams||MULTICALL
788 Make a lightweight callback. See L<perlcall/Lightweight Callbacks>.
789
790 =for apidoc Ams||POP_MULTICALL
791 Closing bracket for a lightweight callback.
792 See L<perlcall/Lightweight Callbacks>.
793
794 =cut
795 */
796
797 #define dMULTICALL \
798     SV **newsp;                 /* set by POPBLOCK */                   \
799     PERL_CONTEXT *cx;                                                   \
800     CV *multicall_cv;                                                   \
801     OP *multicall_cop;                                                  \
802     bool multicall_oldcatch;                                            \
803     U8 hasargs = 0              /* used by PUSHSUB */
804
805 #define PUSH_MULTICALL(the_cv) \
806     STMT_START {                                                        \
807         CV * const _nOnclAshIngNamE_ = the_cv;                          \
808         CV * const cv = _nOnclAshIngNamE_;                              \
809         AV * const padlist = CvPADLIST(cv);                             \
810         ENTER;                                                          \
811         multicall_oldcatch = CATCH_GET;                                 \
812         SAVETMPS; SAVEVPTR(PL_op);                                      \
813         CATCH_SET(TRUE);                                                \
814         PUSHBLOCK(cx, CXt_SUB|CXp_MULTICALL, PL_stack_sp);              \
815         PUSHSUB(cx);                                                    \
816         if (++CvDEPTH(cv) >= 2) {                                       \
817             PERL_STACK_OVERFLOW_CHECK();                                \
818             Perl_pad_push(aTHX_ padlist, CvDEPTH(cv));                  \
819         }                                                               \
820         SAVECOMPPAD();                                                  \
821         PAD_SET_CUR_NOSAVE(padlist, CvDEPTH(cv));                       \
822         multicall_cv = cv;                                              \
823         multicall_cop = CvSTART(cv);                                    \
824     } STMT_END
825
826 #define MULTICALL \
827     STMT_START {                                                        \
828         PL_op = multicall_cop;                                          \
829         CALLRUNOPS(aTHX);                                               \
830     } STMT_END
831
832 #define POP_MULTICALL \
833     STMT_START {                                                        \
834         LEAVESUB(multicall_cv);                                         \
835         CvDEPTH(multicall_cv)--;                                        \
836         POPBLOCK(cx,PL_curpm);                                          \
837         CATCH_SET(multicall_oldcatch);                                  \
838         LEAVE;                                                          \
839     } STMT_END
840
841 /*
842  * Local variables:
843  * c-indentation-style: bsd
844  * c-basic-offset: 4
845  * indent-tabs-mode: t
846  * End:
847  *
848  * ex: set ts=8 sts=4 sw=4 noet:
849  */