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a0d0e21e LW |
1 | =head1 NAME |
2 | ||
3 | perlguts - Perl's Internal Functions | |
4 | ||
5 | =head1 DESCRIPTION | |
6 | ||
7 | This document attempts to describe some of the internal functions of the | |
8 | Perl executable. It is far from complete and probably contains many errors. | |
9 | Please refer any questions or comments to the author below. | |
10 | ||
0a753a76 | 11 | =head1 Variables |
12 | ||
5f05dabc | 13 | =head2 Datatypes |
a0d0e21e LW |
14 | |
15 | Perl has three typedefs that handle Perl's three main data types: | |
16 | ||
17 | SV Scalar Value | |
18 | AV Array Value | |
19 | HV Hash Value | |
20 | ||
d1b91892 | 21 | Each typedef has specific routines that manipulate the various data types. |
a0d0e21e LW |
22 | |
23 | =head2 What is an "IV"? | |
24 | ||
5f05dabc | 25 | Perl uses a special typedef IV which is a simple integer type that is |
26 | guaranteed to be large enough to hold a pointer (as well as an integer). | |
a0d0e21e | 27 | |
d1b91892 AD |
28 | Perl also uses two special typedefs, I32 and I16, which will always be at |
29 | least 32-bits and 16-bits long, respectively. | |
a0d0e21e | 30 | |
5f05dabc | 31 | =head2 Working with SV's |
a0d0e21e LW |
32 | |
33 | An SV can be created and loaded with one command. There are four types of | |
34 | values that can be loaded: an integer value (IV), a double (NV), a string, | |
35 | (PV), and another scalar (SV). | |
36 | ||
37 | The four routines are: | |
38 | ||
39 | SV* newSViv(IV); | |
40 | SV* newSVnv(double); | |
41 | SV* newSVpv(char*, int); | |
42 | SV* newSVsv(SV*); | |
43 | ||
5fb8527f | 44 | To change the value of an *already-existing* SV, there are five routines: |
a0d0e21e LW |
45 | |
46 | void sv_setiv(SV*, IV); | |
47 | void sv_setnv(SV*, double); | |
48 | void sv_setpvn(SV*, char*, int) | |
49 | void sv_setpv(SV*, char*); | |
50 | void sv_setsv(SV*, SV*); | |
51 | ||
52 | Notice that you can choose to specify the length of the string to be | |
d1b91892 | 53 | assigned by using C<sv_setpvn> or C<newSVpv>, or you may allow Perl to |
cb1a09d0 | 54 | calculate the length by using C<sv_setpv> or by specifying 0 as the second |
d1b91892 | 55 | argument to C<newSVpv>. Be warned, though, that Perl will determine the |
a0d0e21e LW |
56 | string's length by using C<strlen>, which depends on the string terminating |
57 | with a NUL character. | |
58 | ||
5f05dabc | 59 | All SV's that will contain strings should, but need not, be terminated |
60 | with a NUL character. If it is not NUL-terminated there is a risk of | |
61 | core dumps and corruptions from code which passes the string to C | |
62 | functions or system calls which expect a NUL-terminated string. | |
63 | Perl's own functions typically add a trailing NUL for this reason. | |
64 | Nevertheless, you should be very careful when you pass a string stored | |
65 | in an SV to a C function or system call. | |
66 | ||
a0d0e21e LW |
67 | To access the actual value that an SV points to, you can use the macros: |
68 | ||
69 | SvIV(SV*) | |
70 | SvNV(SV*) | |
71 | SvPV(SV*, STRLEN len) | |
72 | ||
73 | which will automatically coerce the actual scalar type into an IV, double, | |
74 | or string. | |
75 | ||
76 | In the C<SvPV> macro, the length of the string returned is placed into the | |
77 | variable C<len> (this is a macro, so you do I<not> use C<&len>). If you do not | |
78 | care what the length of the data is, use the global variable C<na>. Remember, | |
79 | however, that Perl allows arbitrary strings of data that may both contain | |
5f05dabc | 80 | NUL's and might not be terminated by a NUL. |
a0d0e21e | 81 | |
07fa94a1 | 82 | If you want to know if the scalar value is TRUE, you can use: |
a0d0e21e LW |
83 | |
84 | SvTRUE(SV*) | |
85 | ||
86 | Although Perl will automatically grow strings for you, if you need to force | |
87 | Perl to allocate more memory for your SV, you can use the macro | |
88 | ||
89 | SvGROW(SV*, STRLEN newlen) | |
90 | ||
91 | which will determine if more memory needs to be allocated. If so, it will | |
92 | call the function C<sv_grow>. Note that C<SvGROW> can only increase, not | |
5f05dabc | 93 | decrease, the allocated memory of an SV and that it does not automatically |
94 | add a byte for the a trailing NUL (perl's own string functions typically do | |
8ebc5c01 | 95 | C<SvGROW(sv, len + 1)>). |
a0d0e21e LW |
96 | |
97 | If you have an SV and want to know what kind of data Perl thinks is stored | |
98 | in it, you can use the following macros to check the type of SV you have. | |
99 | ||
100 | SvIOK(SV*) | |
101 | SvNOK(SV*) | |
102 | SvPOK(SV*) | |
103 | ||
104 | You can get and set the current length of the string stored in an SV with | |
105 | the following macros: | |
106 | ||
107 | SvCUR(SV*) | |
108 | SvCUR_set(SV*, I32 val) | |
109 | ||
cb1a09d0 AD |
110 | You can also get a pointer to the end of the string stored in the SV |
111 | with the macro: | |
112 | ||
113 | SvEND(SV*) | |
114 | ||
115 | But note that these last three macros are valid only if C<SvPOK()> is true. | |
a0d0e21e | 116 | |
d1b91892 AD |
117 | If you want to append something to the end of string stored in an C<SV*>, |
118 | you can use the following functions: | |
119 | ||
120 | void sv_catpv(SV*, char*); | |
121 | void sv_catpvn(SV*, char*, int); | |
122 | void sv_catsv(SV*, SV*); | |
123 | ||
124 | The first function calculates the length of the string to be appended by | |
125 | using C<strlen>. In the second, you specify the length of the string | |
126 | yourself. The third function extends the string stored in the first SV | |
127 | with the string stored in the second SV. It also forces the second SV to | |
128 | be interpreted as a string. | |
129 | ||
a0d0e21e LW |
130 | If you know the name of a scalar variable, you can get a pointer to its SV |
131 | by using the following: | |
132 | ||
5f05dabc | 133 | SV* perl_get_sv("package::varname", FALSE); |
a0d0e21e LW |
134 | |
135 | This returns NULL if the variable does not exist. | |
136 | ||
d1b91892 | 137 | If you want to know if this variable (or any other SV) is actually C<defined>, |
a0d0e21e LW |
138 | you can call: |
139 | ||
140 | SvOK(SV*) | |
141 | ||
142 | The scalar C<undef> value is stored in an SV instance called C<sv_undef>. Its | |
143 | address can be used whenever an C<SV*> is needed. | |
144 | ||
145 | There are also the two values C<sv_yes> and C<sv_no>, which contain Boolean | |
146 | TRUE and FALSE values, respectively. Like C<sv_undef>, their addresses can | |
147 | be used whenever an C<SV*> is needed. | |
148 | ||
149 | Do not be fooled into thinking that C<(SV *) 0> is the same as C<&sv_undef>. | |
150 | Take this code: | |
151 | ||
152 | SV* sv = (SV*) 0; | |
153 | if (I-am-to-return-a-real-value) { | |
154 | sv = sv_2mortal(newSViv(42)); | |
155 | } | |
156 | sv_setsv(ST(0), sv); | |
157 | ||
158 | This code tries to return a new SV (which contains the value 42) if it should | |
159 | return a real value, or undef otherwise. Instead it has returned a null | |
160 | pointer which, somewhere down the line, will cause a segmentation violation, | |
5f05dabc | 161 | bus error, or just weird results. Change the zero to C<&sv_undef> in the first |
162 | line and all will be well. | |
a0d0e21e LW |
163 | |
164 | To free an SV that you've created, call C<SvREFCNT_dec(SV*)>. Normally this | |
5f05dabc | 165 | call is not necessary (see the section on L<Mortality>). |
a0d0e21e | 166 | |
d1b91892 | 167 | =head2 What's Really Stored in an SV? |
a0d0e21e LW |
168 | |
169 | Recall that the usual method of determining the type of scalar you have is | |
5f05dabc | 170 | to use C<Sv*OK> macros. Because a scalar can be both a number and a string, |
d1b91892 | 171 | usually these macros will always return TRUE and calling the C<Sv*V> |
a0d0e21e LW |
172 | macros will do the appropriate conversion of string to integer/double or |
173 | integer/double to string. | |
174 | ||
175 | If you I<really> need to know if you have an integer, double, or string | |
176 | pointer in an SV, you can use the following three macros instead: | |
177 | ||
178 | SvIOKp(SV*) | |
179 | SvNOKp(SV*) | |
180 | SvPOKp(SV*) | |
181 | ||
182 | These will tell you if you truly have an integer, double, or string pointer | |
d1b91892 | 183 | stored in your SV. The "p" stands for private. |
a0d0e21e | 184 | |
07fa94a1 | 185 | In general, though, it's best to use the C<Sv*V> macros. |
a0d0e21e | 186 | |
5f05dabc | 187 | =head2 Working with AV's |
a0d0e21e | 188 | |
07fa94a1 JO |
189 | There are two ways to create and load an AV. The first method creates an |
190 | empty AV: | |
a0d0e21e LW |
191 | |
192 | AV* newAV(); | |
193 | ||
5f05dabc | 194 | The second method both creates the AV and initially populates it with SV's: |
a0d0e21e LW |
195 | |
196 | AV* av_make(I32 num, SV **ptr); | |
197 | ||
5f05dabc | 198 | The second argument points to an array containing C<num> C<SV*>'s. Once the |
199 | AV has been created, the SV's can be destroyed, if so desired. | |
a0d0e21e | 200 | |
5f05dabc | 201 | Once the AV has been created, the following operations are possible on AV's: |
a0d0e21e LW |
202 | |
203 | void av_push(AV*, SV*); | |
204 | SV* av_pop(AV*); | |
205 | SV* av_shift(AV*); | |
206 | void av_unshift(AV*, I32 num); | |
207 | ||
208 | These should be familiar operations, with the exception of C<av_unshift>. | |
209 | This routine adds C<num> elements at the front of the array with the C<undef> | |
210 | value. You must then use C<av_store> (described below) to assign values | |
211 | to these new elements. | |
212 | ||
213 | Here are some other functions: | |
214 | ||
5f05dabc | 215 | I32 av_len(AV*); |
a0d0e21e | 216 | SV** av_fetch(AV*, I32 key, I32 lval); |
a0d0e21e | 217 | SV** av_store(AV*, I32 key, SV* val); |
a0d0e21e | 218 | |
5f05dabc | 219 | The C<av_len> function returns the highest index value in array (just |
220 | like $#array in Perl). If the array is empty, -1 is returned. The | |
221 | C<av_fetch> function returns the value at index C<key>, but if C<lval> | |
222 | is non-zero, then C<av_fetch> will store an undef value at that index. | |
223 | The C<av_store> function stores the value C<val> at index C<key>. | |
224 | note that C<av_fetch> and C<av_store> both return C<SV**>'s, not C<SV*>'s | |
225 | as their return value. | |
d1b91892 | 226 | |
a0d0e21e | 227 | void av_clear(AV*); |
a0d0e21e | 228 | void av_undef(AV*); |
cb1a09d0 | 229 | void av_extend(AV*, I32 key); |
5f05dabc | 230 | |
231 | The C<av_clear> function deletes all the elements in the AV* array, but | |
232 | does not actually delete the array itself. The C<av_undef> function will | |
233 | delete all the elements in the array plus the array itself. The | |
234 | C<av_extend> function extends the array so that it contains C<key> | |
235 | elements. If C<key> is less than the current length of the array, then | |
236 | nothing is done. | |
a0d0e21e LW |
237 | |
238 | If you know the name of an array variable, you can get a pointer to its AV | |
239 | by using the following: | |
240 | ||
5f05dabc | 241 | AV* perl_get_av("package::varname", FALSE); |
a0d0e21e LW |
242 | |
243 | This returns NULL if the variable does not exist. | |
244 | ||
5f05dabc | 245 | =head2 Working with HV's |
a0d0e21e LW |
246 | |
247 | To create an HV, you use the following routine: | |
248 | ||
249 | HV* newHV(); | |
250 | ||
5f05dabc | 251 | Once the HV has been created, the following operations are possible on HV's: |
a0d0e21e LW |
252 | |
253 | SV** hv_store(HV*, char* key, U32 klen, SV* val, U32 hash); | |
254 | SV** hv_fetch(HV*, char* key, U32 klen, I32 lval); | |
255 | ||
5f05dabc | 256 | The C<klen> parameter is the length of the key being passed in (Note that |
257 | you cannot pass 0 in as a value of C<klen> to tell Perl to measure the | |
258 | length of the key). The C<val> argument contains the SV pointer to the | |
259 | scalar being stored, and C<hash> is the pre-computed hash value (zero if | |
260 | you want C<hv_store> to calculate it for you). The C<lval> parameter | |
261 | indicates whether this fetch is actually a part of a store operation, in | |
262 | which case a new undefined value will be added to the HV with the supplied | |
263 | key and C<hv_fetch> will return as if the value had already existed. | |
a0d0e21e | 264 | |
5f05dabc | 265 | Remember that C<hv_store> and C<hv_fetch> return C<SV**>'s and not just |
266 | C<SV*>. To access the scalar value, you must first dereference the return | |
267 | value. However, you should check to make sure that the return value is | |
268 | not NULL before dereferencing it. | |
a0d0e21e LW |
269 | |
270 | These two functions check if a hash table entry exists, and deletes it. | |
271 | ||
272 | bool hv_exists(HV*, char* key, U32 klen); | |
d1b91892 | 273 | SV* hv_delete(HV*, char* key, U32 klen, I32 flags); |
a0d0e21e | 274 | |
5f05dabc | 275 | If C<flags> does not include the C<G_DISCARD> flag then C<hv_delete> will |
276 | create and return a mortal copy of the deleted value. | |
277 | ||
a0d0e21e LW |
278 | And more miscellaneous functions: |
279 | ||
280 | void hv_clear(HV*); | |
a0d0e21e | 281 | void hv_undef(HV*); |
5f05dabc | 282 | |
283 | Like their AV counterparts, C<hv_clear> deletes all the entries in the hash | |
284 | table but does not actually delete the hash table. The C<hv_undef> deletes | |
285 | both the entries and the hash table itself. | |
a0d0e21e | 286 | |
d1b91892 AD |
287 | Perl keeps the actual data in linked list of structures with a typedef of HE. |
288 | These contain the actual key and value pointers (plus extra administrative | |
289 | overhead). The key is a string pointer; the value is an C<SV*>. However, | |
290 | once you have an C<HE*>, to get the actual key and value, use the routines | |
291 | specified below. | |
292 | ||
a0d0e21e LW |
293 | I32 hv_iterinit(HV*); |
294 | /* Prepares starting point to traverse hash table */ | |
295 | HE* hv_iternext(HV*); | |
296 | /* Get the next entry, and return a pointer to a | |
297 | structure that has both the key and value */ | |
298 | char* hv_iterkey(HE* entry, I32* retlen); | |
299 | /* Get the key from an HE structure and also return | |
300 | the length of the key string */ | |
cb1a09d0 | 301 | SV* hv_iterval(HV*, HE* entry); |
a0d0e21e LW |
302 | /* Return a SV pointer to the value of the HE |
303 | structure */ | |
cb1a09d0 | 304 | SV* hv_iternextsv(HV*, char** key, I32* retlen); |
d1b91892 AD |
305 | /* This convenience routine combines hv_iternext, |
306 | hv_iterkey, and hv_iterval. The key and retlen | |
307 | arguments are return values for the key and its | |
308 | length. The value is returned in the SV* argument */ | |
a0d0e21e LW |
309 | |
310 | If you know the name of a hash variable, you can get a pointer to its HV | |
311 | by using the following: | |
312 | ||
5f05dabc | 313 | HV* perl_get_hv("package::varname", FALSE); |
a0d0e21e LW |
314 | |
315 | This returns NULL if the variable does not exist. | |
316 | ||
8ebc5c01 | 317 | The hash algorithm is defined in the C<PERL_HASH(hash, key, klen)> macro: |
a0d0e21e LW |
318 | |
319 | i = klen; | |
320 | hash = 0; | |
321 | s = key; | |
322 | while (i--) | |
323 | hash = hash * 33 + *s++; | |
324 | ||
325 | =head2 References | |
326 | ||
d1b91892 AD |
327 | References are a special type of scalar that point to other data types |
328 | (including references). | |
a0d0e21e | 329 | |
07fa94a1 | 330 | To create a reference, use either of the following functions: |
a0d0e21e | 331 | |
5f05dabc | 332 | SV* newRV_inc((SV*) thing); |
333 | SV* newRV_noinc((SV*) thing); | |
a0d0e21e | 334 | |
5f05dabc | 335 | The C<thing> argument can be any of an C<SV*>, C<AV*>, or C<HV*>. The |
07fa94a1 JO |
336 | functions are identical except that C<newRV_inc> increments the reference |
337 | count of the C<thing>, while C<newRV_noinc> does not. For historical | |
338 | reasons, C<newRV> is a synonym for C<newRV_inc>. | |
339 | ||
340 | Once you have a reference, you can use the following macro to dereference | |
341 | the reference: | |
a0d0e21e LW |
342 | |
343 | SvRV(SV*) | |
344 | ||
345 | then call the appropriate routines, casting the returned C<SV*> to either an | |
d1b91892 | 346 | C<AV*> or C<HV*>, if required. |
a0d0e21e | 347 | |
d1b91892 | 348 | To determine if an SV is a reference, you can use the following macro: |
a0d0e21e LW |
349 | |
350 | SvROK(SV*) | |
351 | ||
07fa94a1 JO |
352 | To discover what type of value the reference refers to, use the following |
353 | macro and then check the return value. | |
d1b91892 AD |
354 | |
355 | SvTYPE(SvRV(SV*)) | |
356 | ||
357 | The most useful types that will be returned are: | |
358 | ||
359 | SVt_IV Scalar | |
360 | SVt_NV Scalar | |
361 | SVt_PV Scalar | |
5f05dabc | 362 | SVt_RV Scalar |
d1b91892 AD |
363 | SVt_PVAV Array |
364 | SVt_PVHV Hash | |
365 | SVt_PVCV Code | |
5f05dabc | 366 | SVt_PVGV Glob (possible a file handle) |
367 | SVt_PVMG Blessed or Magical Scalar | |
368 | ||
369 | See the sv.h header file for more details. | |
d1b91892 | 370 | |
cb1a09d0 AD |
371 | =head2 Blessed References and Class Objects |
372 | ||
373 | References are also used to support object-oriented programming. In the | |
374 | OO lexicon, an object is simply a reference that has been blessed into a | |
375 | package (or class). Once blessed, the programmer may now use the reference | |
376 | to access the various methods in the class. | |
377 | ||
378 | A reference can be blessed into a package with the following function: | |
379 | ||
380 | SV* sv_bless(SV* sv, HV* stash); | |
381 | ||
382 | The C<sv> argument must be a reference. The C<stash> argument specifies | |
55497cff | 383 | which class the reference will belong to. See the section on L<Stashes> |
cb1a09d0 AD |
384 | for information on converting class names into stashes. |
385 | ||
386 | /* Still under construction */ | |
387 | ||
388 | Upgrades rv to reference if not already one. Creates new SV for rv to | |
8ebc5c01 | 389 | point to. If C<classname> is non-null, the SV is blessed into the specified |
390 | class. SV is returned. | |
cb1a09d0 AD |
391 | |
392 | SV* newSVrv(SV* rv, char* classname); | |
393 | ||
8ebc5c01 | 394 | Copies integer or double into an SV whose reference is C<rv>. SV is blessed |
395 | if C<classname> is non-null. | |
cb1a09d0 AD |
396 | |
397 | SV* sv_setref_iv(SV* rv, char* classname, IV iv); | |
398 | SV* sv_setref_nv(SV* rv, char* classname, NV iv); | |
399 | ||
5f05dabc | 400 | Copies the pointer value (I<the address, not the string!>) into an SV whose |
8ebc5c01 | 401 | reference is rv. SV is blessed if C<classname> is non-null. |
cb1a09d0 AD |
402 | |
403 | SV* sv_setref_pv(SV* rv, char* classname, PV iv); | |
404 | ||
8ebc5c01 | 405 | Copies string into an SV whose reference is C<rv>. Set length to 0 to let |
406 | Perl calculate the string length. SV is blessed if C<classname> is non-null. | |
cb1a09d0 AD |
407 | |
408 | SV* sv_setref_pvn(SV* rv, char* classname, PV iv, int length); | |
409 | ||
410 | int sv_isa(SV* sv, char* name); | |
411 | int sv_isobject(SV* sv); | |
412 | ||
5f05dabc | 413 | =head2 Creating New Variables |
cb1a09d0 | 414 | |
5f05dabc | 415 | To create a new Perl variable with an undef value which can be accessed from |
416 | your Perl script, use the following routines, depending on the variable type. | |
cb1a09d0 | 417 | |
5f05dabc | 418 | SV* perl_get_sv("package::varname", TRUE); |
419 | AV* perl_get_av("package::varname", TRUE); | |
420 | HV* perl_get_hv("package::varname", TRUE); | |
cb1a09d0 AD |
421 | |
422 | Notice the use of TRUE as the second parameter. The new variable can now | |
423 | be set, using the routines appropriate to the data type. | |
424 | ||
5f05dabc | 425 | There are additional macros whose values may be bitwise OR'ed with the |
426 | C<TRUE> argument to enable certain extra features. Those bits are: | |
cb1a09d0 | 427 | |
5f05dabc | 428 | GV_ADDMULTI Marks the variable as multiply defined, thus preventing the |
429 | "Indentifier <varname> used only once: possible typo" warning. | |
07fa94a1 JO |
430 | GV_ADDWARN Issues the warning "Had to create <varname> unexpectedly" if |
431 | the variable did not exist before the function was called. | |
cb1a09d0 | 432 | |
07fa94a1 JO |
433 | If you do not specify a package name, the variable is created in the current |
434 | package. | |
cb1a09d0 | 435 | |
5f05dabc | 436 | =head2 Reference Counts and Mortality |
a0d0e21e | 437 | |
55497cff | 438 | Perl uses an reference count-driven garbage collection mechanism. SV's, |
439 | AV's, or HV's (xV for short in the following) start their life with a | |
440 | reference count of 1. If the reference count of an xV ever drops to 0, | |
07fa94a1 | 441 | then it will be destroyed and its memory made available for reuse. |
55497cff | 442 | |
443 | This normally doesn't happen at the Perl level unless a variable is | |
5f05dabc | 444 | undef'ed or the last variable holding a reference to it is changed or |
445 | overwritten. At the internal level, however, reference counts can be | |
55497cff | 446 | manipulated with the following macros: |
447 | ||
448 | int SvREFCNT(SV* sv); | |
5f05dabc | 449 | SV* SvREFCNT_inc(SV* sv); |
55497cff | 450 | void SvREFCNT_dec(SV* sv); |
451 | ||
452 | However, there is one other function which manipulates the reference | |
07fa94a1 JO |
453 | count of its argument. The C<newRV_inc> function, you will recall, |
454 | creates a reference to the specified argument. As a side effect, | |
455 | it increments the argument's reference count. If this is not what | |
456 | you want, use C<newRV_noinc> instead. | |
457 | ||
458 | For example, imagine you want to return a reference from an XSUB function. | |
459 | Inside the XSUB routine, you create an SV which initially has a reference | |
460 | count of one. Then you call C<newRV_inc>, passing it the just-created SV. | |
5f05dabc | 461 | This returns the reference as a new SV, but the reference count of the |
462 | SV you passed to C<newRV_inc> has been incremented to two. Now you | |
07fa94a1 JO |
463 | return the reference from the XSUB routine and forget about the SV. |
464 | But Perl hasn't! Whenever the returned reference is destroyed, the | |
465 | reference count of the original SV is decreased to one and nothing happens. | |
466 | The SV will hang around without any way to access it until Perl itself | |
467 | terminates. This is a memory leak. | |
5f05dabc | 468 | |
469 | The correct procedure, then, is to use C<newRV_noinc> instead of | |
faed5253 JO |
470 | C<newRV_inc>. Then, if and when the last reference is destroyed, |
471 | the reference count of the SV will go to zero and it will be destroyed, | |
07fa94a1 | 472 | stopping any memory leak. |
55497cff | 473 | |
5f05dabc | 474 | There are some convenience functions available that can help with the |
07fa94a1 JO |
475 | destruction of xV's. These functions introduce the concept of "mortality". |
476 | An xV that is mortal has had its reference count marked to be decremented, | |
477 | but not actually decremented, until "a short time later". Generally the | |
478 | term "short time later" means a single Perl statement, such as a call to | |
479 | an XSUB function. The actual determinant for when mortal xV's have their | |
480 | reference count decremented depends on two macros, SAVETMPS and FREETMPS. | |
481 | See L<perlcall> and L<perlxs> for more details on these macros. | |
55497cff | 482 | |
483 | "Mortalization" then is at its simplest a deferred C<SvREFCNT_dec>. | |
484 | However, if you mortalize a variable twice, the reference count will | |
485 | later be decremented twice. | |
486 | ||
487 | You should be careful about creating mortal variables. Strange things | |
488 | can happen if you make the same value mortal within multiple contexts, | |
5f05dabc | 489 | or if you make a variable mortal multiple times. |
a0d0e21e LW |
490 | |
491 | To create a mortal variable, use the functions: | |
492 | ||
493 | SV* sv_newmortal() | |
494 | SV* sv_2mortal(SV*) | |
495 | SV* sv_mortalcopy(SV*) | |
496 | ||
5f05dabc | 497 | The first call creates a mortal SV, the second converts an existing |
498 | SV to a mortal SV (and thus defers a call to C<SvREFCNT_dec>), and the | |
499 | third creates a mortal copy of an existing SV. | |
a0d0e21e | 500 | |
faed5253 JO |
501 | The mortal routines are not just for SV's -- AV's and HV's can be |
502 | made mortal by passing their address (type-casted to C<SV*>) to the | |
07fa94a1 | 503 | C<sv_2mortal> or C<sv_mortalcopy> routines. |
a0d0e21e | 504 | |
5f05dabc | 505 | =head2 Stashes and Globs |
a0d0e21e | 506 | |
aa689395 | 507 | A "stash" is a hash that contains all of the different objects that |
508 | are contained within a package. Each key of the stash is a symbol | |
509 | name (shared by all the different types of objects that have the same | |
510 | name), and each value in the hash table is a GV (Glob Value). This GV | |
511 | in turn contains references to the various objects of that name, | |
512 | including (but not limited to) the following: | |
cb1a09d0 | 513 | |
a0d0e21e LW |
514 | Scalar Value |
515 | Array Value | |
516 | Hash Value | |
517 | File Handle | |
518 | Directory Handle | |
519 | Format | |
520 | Subroutine | |
521 | ||
5f05dabc | 522 | There is a single stash called "defstash" that holds the items that exist |
523 | in the "main" package. To get at the items in other packages, append the | |
524 | string "::" to the package name. The items in the "Foo" package are in | |
525 | the stash "Foo::" in defstash. The items in the "Bar::Baz" package are | |
526 | in the stash "Baz::" in "Bar::"'s stash. | |
a0d0e21e | 527 | |
d1b91892 | 528 | To get the stash pointer for a particular package, use the function: |
a0d0e21e LW |
529 | |
530 | HV* gv_stashpv(char* name, I32 create) | |
531 | HV* gv_stashsv(SV*, I32 create) | |
532 | ||
533 | The first function takes a literal string, the second uses the string stored | |
d1b91892 | 534 | in the SV. Remember that a stash is just a hash table, so you get back an |
cb1a09d0 | 535 | C<HV*>. The C<create> flag will create a new package if it is set. |
a0d0e21e LW |
536 | |
537 | The name that C<gv_stash*v> wants is the name of the package whose symbol table | |
538 | you want. The default package is called C<main>. If you have multiply nested | |
d1b91892 AD |
539 | packages, pass their names to C<gv_stash*v>, separated by C<::> as in the Perl |
540 | language itself. | |
a0d0e21e LW |
541 | |
542 | Alternately, if you have an SV that is a blessed reference, you can find | |
543 | out the stash pointer by using: | |
544 | ||
545 | HV* SvSTASH(SvRV(SV*)); | |
546 | ||
547 | then use the following to get the package name itself: | |
548 | ||
549 | char* HvNAME(HV* stash); | |
550 | ||
5f05dabc | 551 | If you need to bless or re-bless an object you can use the following |
552 | function: | |
a0d0e21e LW |
553 | |
554 | SV* sv_bless(SV*, HV* stash) | |
555 | ||
556 | where the first argument, an C<SV*>, must be a reference, and the second | |
557 | argument is a stash. The returned C<SV*> can now be used in the same way | |
558 | as any other SV. | |
559 | ||
d1b91892 AD |
560 | For more information on references and blessings, consult L<perlref>. |
561 | ||
0a753a76 | 562 | =head2 Double-Typed SV's |
563 | ||
564 | Scalar variables normally contain only one type of value, an integer, | |
565 | double, pointer, or reference. Perl will automatically convert the | |
566 | actual scalar data from the stored type into the requested type. | |
567 | ||
568 | Some scalar variables contain more than one type of scalar data. For | |
569 | example, the variable C<$!> contains either the numeric value of C<errno> | |
570 | or its string equivalent from either C<strerror> or C<sys_errlist[]>. | |
571 | ||
572 | To force multiple data values into an SV, you must do two things: use the | |
573 | C<sv_set*v> routines to add the additional scalar type, then set a flag | |
574 | so that Perl will believe it contains more than one type of data. The | |
575 | four macros to set the flags are: | |
576 | ||
577 | SvIOK_on | |
578 | SvNOK_on | |
579 | SvPOK_on | |
580 | SvROK_on | |
581 | ||
582 | The particular macro you must use depends on which C<sv_set*v> routine | |
583 | you called first. This is because every C<sv_set*v> routine turns on | |
584 | only the bit for the particular type of data being set, and turns off | |
585 | all the rest. | |
586 | ||
587 | For example, to create a new Perl variable called "dberror" that contains | |
588 | both the numeric and descriptive string error values, you could use the | |
589 | following code: | |
590 | ||
591 | extern int dberror; | |
592 | extern char *dberror_list; | |
593 | ||
594 | SV* sv = perl_get_sv("dberror", TRUE); | |
595 | sv_setiv(sv, (IV) dberror); | |
596 | sv_setpv(sv, dberror_list[dberror]); | |
597 | SvIOK_on(sv); | |
598 | ||
599 | If the order of C<sv_setiv> and C<sv_setpv> had been reversed, then the | |
600 | macro C<SvPOK_on> would need to be called instead of C<SvIOK_on>. | |
601 | ||
602 | =head2 Magic Variables | |
a0d0e21e | 603 | |
d1b91892 AD |
604 | [This section still under construction. Ignore everything here. Post no |
605 | bills. Everything not permitted is forbidden.] | |
606 | ||
d1b91892 AD |
607 | Any SV may be magical, that is, it has special features that a normal |
608 | SV does not have. These features are stored in the SV structure in a | |
5f05dabc | 609 | linked list of C<struct magic>'s, typedef'ed to C<MAGIC>. |
d1b91892 AD |
610 | |
611 | struct magic { | |
612 | MAGIC* mg_moremagic; | |
613 | MGVTBL* mg_virtual; | |
614 | U16 mg_private; | |
615 | char mg_type; | |
616 | U8 mg_flags; | |
617 | SV* mg_obj; | |
618 | char* mg_ptr; | |
619 | I32 mg_len; | |
620 | }; | |
621 | ||
622 | Note this is current as of patchlevel 0, and could change at any time. | |
623 | ||
624 | =head2 Assigning Magic | |
625 | ||
626 | Perl adds magic to an SV using the sv_magic function: | |
627 | ||
628 | void sv_magic(SV* sv, SV* obj, int how, char* name, I32 namlen); | |
629 | ||
630 | The C<sv> argument is a pointer to the SV that is to acquire a new magical | |
631 | feature. | |
632 | ||
633 | If C<sv> is not already magical, Perl uses the C<SvUPGRADE> macro to | |
634 | set the C<SVt_PVMG> flag for the C<sv>. Perl then continues by adding | |
635 | it to the beginning of the linked list of magical features. Any prior | |
636 | entry of the same type of magic is deleted. Note that this can be | |
5fb8527f | 637 | overridden, and multiple instances of the same type of magic can be |
d1b91892 AD |
638 | associated with an SV. |
639 | ||
640 | The C<name> and C<namlem> arguments are used to associate a string with | |
641 | the magic, typically the name of a variable. C<namlem> is stored in the | |
55497cff | 642 | C<mg_len> field and if C<name> is non-null and C<namlem> >= 0 a malloc'd |
d1b91892 AD |
643 | copy of the name is stored in C<mg_ptr> field. |
644 | ||
645 | The sv_magic function uses C<how> to determine which, if any, predefined | |
646 | "Magic Virtual Table" should be assigned to the C<mg_virtual> field. | |
cb1a09d0 AD |
647 | See the "Magic Virtual Table" section below. The C<how> argument is also |
648 | stored in the C<mg_type> field. | |
d1b91892 AD |
649 | |
650 | The C<obj> argument is stored in the C<mg_obj> field of the C<MAGIC> | |
651 | structure. If it is not the same as the C<sv> argument, the reference | |
652 | count of the C<obj> object is incremented. If it is the same, or if | |
653 | the C<how> argument is "#", or if it is a null pointer, then C<obj> is | |
654 | merely stored, without the reference count being incremented. | |
655 | ||
cb1a09d0 AD |
656 | There is also a function to add magic to an C<HV>: |
657 | ||
658 | void hv_magic(HV *hv, GV *gv, int how); | |
659 | ||
660 | This simply calls C<sv_magic> and coerces the C<gv> argument into an C<SV>. | |
661 | ||
662 | To remove the magic from an SV, call the function sv_unmagic: | |
663 | ||
664 | void sv_unmagic(SV *sv, int type); | |
665 | ||
666 | The C<type> argument should be equal to the C<how> value when the C<SV> | |
667 | was initially made magical. | |
668 | ||
d1b91892 AD |
669 | =head2 Magic Virtual Tables |
670 | ||
671 | The C<mg_virtual> field in the C<MAGIC> structure is a pointer to a | |
672 | C<MGVTBL>, which is a structure of function pointers and stands for | |
673 | "Magic Virtual Table" to handle the various operations that might be | |
674 | applied to that variable. | |
675 | ||
676 | The C<MGVTBL> has five pointers to the following routine types: | |
677 | ||
678 | int (*svt_get)(SV* sv, MAGIC* mg); | |
679 | int (*svt_set)(SV* sv, MAGIC* mg); | |
680 | U32 (*svt_len)(SV* sv, MAGIC* mg); | |
681 | int (*svt_clear)(SV* sv, MAGIC* mg); | |
682 | int (*svt_free)(SV* sv, MAGIC* mg); | |
683 | ||
684 | This MGVTBL structure is set at compile-time in C<perl.h> and there are | |
685 | currently 19 types (or 21 with overloading turned on). These different | |
686 | structures contain pointers to various routines that perform additional | |
687 | actions depending on which function is being called. | |
688 | ||
689 | Function pointer Action taken | |
690 | ---------------- ------------ | |
691 | svt_get Do something after the value of the SV is retrieved. | |
692 | svt_set Do something after the SV is assigned a value. | |
693 | svt_len Report on the SV's length. | |
694 | svt_clear Clear something the SV represents. | |
695 | svt_free Free any extra storage associated with the SV. | |
696 | ||
697 | For instance, the MGVTBL structure called C<vtbl_sv> (which corresponds | |
698 | to an C<mg_type> of '\0') contains: | |
699 | ||
700 | { magic_get, magic_set, magic_len, 0, 0 } | |
701 | ||
702 | Thus, when an SV is determined to be magical and of type '\0', if a get | |
703 | operation is being performed, the routine C<magic_get> is called. All | |
704 | the various routines for the various magical types begin with C<magic_>. | |
705 | ||
706 | The current kinds of Magic Virtual Tables are: | |
707 | ||
07fa94a1 | 708 | mg_type MGVTBL Type of magical |
5f05dabc | 709 | ------- ------ ---------------------------- |
d1b91892 AD |
710 | \0 vtbl_sv Regexp??? |
711 | A vtbl_amagic Operator Overloading | |
712 | a vtbl_amagicelem Operator Overloading | |
713 | c 0 Used in Operator Overloading | |
714 | B vtbl_bm Boyer-Moore??? | |
715 | E vtbl_env %ENV hash | |
716 | e vtbl_envelem %ENV hash element | |
717 | g vtbl_mglob Regexp /g flag??? | |
718 | I vtbl_isa @ISA array | |
719 | i vtbl_isaelem @ISA array element | |
720 | L 0 (but sets RMAGICAL) Perl Module/Debugger??? | |
721 | l vtbl_dbline Debugger? | |
44a8e56a | 722 | o vtbl_collxfrm Locale transformation |
d1b91892 AD |
723 | P vtbl_pack Tied Array or Hash |
724 | p vtbl_packelem Tied Array or Hash element | |
725 | q vtbl_packelem Tied Scalar or Handle | |
726 | S vtbl_sig Signal Hash | |
727 | s vtbl_sigelem Signal Hash element | |
728 | t vtbl_taint Taintedness | |
729 | U vtbl_uvar ??? | |
730 | v vtbl_vec Vector | |
731 | x vtbl_substr Substring??? | |
e616eb7b | 732 | y vtbl_itervar Shadow "foreach" iterator variable |
d1b91892 AD |
733 | * vtbl_glob GV??? |
734 | # vtbl_arylen Array Length | |
735 | . vtbl_pos $. scalar variable | |
5f05dabc | 736 | ~ None Used by certain extensions |
d1b91892 AD |
737 | |
738 | When an upper-case and lower-case letter both exist in the table, then the | |
739 | upper-case letter is used to represent some kind of composite type (a list | |
740 | or a hash), and the lower-case letter is used to represent an element of | |
741 | that composite type. | |
742 | ||
5f05dabc | 743 | The '~' magic type is defined specifically for use by extensions and |
744 | will not be used by perl itself. Extensions can use ~ magic to 'attach' | |
745 | private information to variables (typically objects). This is especially | |
746 | useful because there is no way for normal perl code to corrupt this | |
747 | private information (unlike using extra elements of a hash object). | |
748 | ||
749 | Note that because multiple extensions may be using ~ magic it is | |
750 | important for extensions to take extra care with it. Typically only | |
751 | using it on objects blessed into the same class as the extension | |
752 | is sufficient. It may also be appropriate to add an I32 'signature' | |
753 | at the top of the private data area and check that. | |
754 | ||
d1b91892 AD |
755 | =head2 Finding Magic |
756 | ||
757 | MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */ | |
758 | ||
759 | This routine returns a pointer to the C<MAGIC> structure stored in the SV. | |
760 | If the SV does not have that magical feature, C<NULL> is returned. Also, | |
761 | if the SV is not of type SVt_PVMG, Perl may core-dump. | |
762 | ||
763 | int mg_copy(SV* sv, SV* nsv, char* key, STRLEN klen); | |
764 | ||
765 | This routine checks to see what types of magic C<sv> has. If the mg_type | |
766 | field is an upper-case letter, then the mg_obj is copied to C<nsv>, but | |
767 | the mg_type field is changed to be the lower-case letter. | |
a0d0e21e | 768 | |
0a753a76 | 769 | =head1 Subroutines |
a0d0e21e | 770 | |
5f05dabc | 771 | =head2 XSUB's and the Argument Stack |
772 | ||
773 | The XSUB mechanism is a simple way for Perl programs to access C subroutines. | |
774 | An XSUB routine will have a stack that contains the arguments from the Perl | |
775 | program, and a way to map from the Perl data structures to a C equivalent. | |
776 | ||
777 | The stack arguments are accessible through the C<ST(n)> macro, which returns | |
778 | the C<n>'th stack argument. Argument 0 is the first argument passed in the | |
779 | Perl subroutine call. These arguments are C<SV*>, and can be used anywhere | |
780 | an C<SV*> is used. | |
781 | ||
782 | Most of the time, output from the C routine can be handled through use of | |
783 | the RETVAL and OUTPUT directives. However, there are some cases where the | |
784 | argument stack is not already long enough to handle all the return values. | |
785 | An example is the POSIX tzname() call, which takes no arguments, but returns | |
786 | two, the local time zone's standard and summer time abbreviations. | |
787 | ||
788 | To handle this situation, the PPCODE directive is used and the stack is | |
789 | extended using the macro: | |
790 | ||
791 | EXTEND(sp, num); | |
792 | ||
793 | where C<sp> is the stack pointer, and C<num> is the number of elements the | |
794 | stack should be extended by. | |
795 | ||
796 | Now that there is room on the stack, values can be pushed on it using the | |
797 | macros to push IV's, doubles, strings, and SV pointers respectively: | |
798 | ||
799 | PUSHi(IV) | |
800 | PUSHn(double) | |
801 | PUSHp(char*, I32) | |
802 | PUSHs(SV*) | |
803 | ||
804 | And now the Perl program calling C<tzname>, the two values will be assigned | |
805 | as in: | |
806 | ||
807 | ($standard_abbrev, $summer_abbrev) = POSIX::tzname; | |
808 | ||
809 | An alternate (and possibly simpler) method to pushing values on the stack is | |
810 | to use the macros: | |
811 | ||
812 | XPUSHi(IV) | |
813 | XPUSHn(double) | |
814 | XPUSHp(char*, I32) | |
815 | XPUSHs(SV*) | |
816 | ||
817 | These macros automatically adjust the stack for you, if needed. Thus, you | |
818 | do not need to call C<EXTEND> to extend the stack. | |
819 | ||
820 | For more information, consult L<perlxs> and L<perlxstut>. | |
821 | ||
822 | =head2 Calling Perl Routines from within C Programs | |
a0d0e21e LW |
823 | |
824 | There are four routines that can be used to call a Perl subroutine from | |
825 | within a C program. These four are: | |
826 | ||
827 | I32 perl_call_sv(SV*, I32); | |
828 | I32 perl_call_pv(char*, I32); | |
829 | I32 perl_call_method(char*, I32); | |
830 | I32 perl_call_argv(char*, I32, register char**); | |
831 | ||
d1b91892 AD |
832 | The routine most often used is C<perl_call_sv>. The C<SV*> argument |
833 | contains either the name of the Perl subroutine to be called, or a | |
834 | reference to the subroutine. The second argument consists of flags | |
835 | that control the context in which the subroutine is called, whether | |
836 | or not the subroutine is being passed arguments, how errors should be | |
837 | trapped, and how to treat return values. | |
a0d0e21e LW |
838 | |
839 | All four routines return the number of arguments that the subroutine returned | |
840 | on the Perl stack. | |
841 | ||
d1b91892 AD |
842 | When using any of these routines (except C<perl_call_argv>), the programmer |
843 | must manipulate the Perl stack. These include the following macros and | |
844 | functions: | |
a0d0e21e LW |
845 | |
846 | dSP | |
847 | PUSHMARK() | |
848 | PUTBACK | |
849 | SPAGAIN | |
850 | ENTER | |
851 | SAVETMPS | |
852 | FREETMPS | |
853 | LEAVE | |
854 | XPUSH*() | |
cb1a09d0 | 855 | POP*() |
a0d0e21e | 856 | |
5f05dabc | 857 | For a detailed description of calling conventions from C to Perl, |
858 | consult L<perlcall>. | |
a0d0e21e | 859 | |
5f05dabc | 860 | =head2 Memory Allocation |
a0d0e21e | 861 | |
5f05dabc | 862 | It is suggested that you use the version of malloc that is distributed |
863 | with Perl. It keeps pools of various sizes of unallocated memory in | |
07fa94a1 JO |
864 | order to satisfy allocation requests more quickly. However, on some |
865 | platforms, it may cause spurious malloc or free errors. | |
d1b91892 AD |
866 | |
867 | New(x, pointer, number, type); | |
868 | Newc(x, pointer, number, type, cast); | |
869 | Newz(x, pointer, number, type); | |
870 | ||
07fa94a1 | 871 | These three macros are used to initially allocate memory. |
5f05dabc | 872 | |
873 | The first argument C<x> was a "magic cookie" that was used to keep track | |
874 | of who called the macro, to help when debugging memory problems. However, | |
07fa94a1 JO |
875 | the current code makes no use of this feature (most Perl developers now |
876 | use run-time memory checkers), so this argument can be any number. | |
5f05dabc | 877 | |
878 | The second argument C<pointer> should be the name of a variable that will | |
879 | point to the newly allocated memory. | |
d1b91892 | 880 | |
d1b91892 AD |
881 | The third and fourth arguments C<number> and C<type> specify how many of |
882 | the specified type of data structure should be allocated. The argument | |
883 | C<type> is passed to C<sizeof>. The final argument to C<Newc>, C<cast>, | |
884 | should be used if the C<pointer> argument is different from the C<type> | |
885 | argument. | |
886 | ||
887 | Unlike the C<New> and C<Newc> macros, the C<Newz> macro calls C<memzero> | |
888 | to zero out all the newly allocated memory. | |
889 | ||
890 | Renew(pointer, number, type); | |
891 | Renewc(pointer, number, type, cast); | |
892 | Safefree(pointer) | |
893 | ||
894 | These three macros are used to change a memory buffer size or to free a | |
895 | piece of memory no longer needed. The arguments to C<Renew> and C<Renewc> | |
896 | match those of C<New> and C<Newc> with the exception of not needing the | |
897 | "magic cookie" argument. | |
898 | ||
899 | Move(source, dest, number, type); | |
900 | Copy(source, dest, number, type); | |
901 | Zero(dest, number, type); | |
902 | ||
903 | These three macros are used to move, copy, or zero out previously allocated | |
904 | memory. The C<source> and C<dest> arguments point to the source and | |
905 | destination starting points. Perl will move, copy, or zero out C<number> | |
906 | instances of the size of the C<type> data structure (using the C<sizeof> | |
907 | function). | |
a0d0e21e | 908 | |
5f05dabc | 909 | =head2 PerlIO |
ce3d39e2 | 910 | |
5f05dabc | 911 | The most recent development releases of Perl has been experimenting with |
912 | removing Perl's dependency on the "normal" standard I/O suite and allowing | |
913 | other stdio implementations to be used. This involves creating a new | |
914 | abstraction layer that then calls whichever implementation of stdio Perl | |
915 | was compiled with. All XSUB's should now use the functions in the PerlIO | |
916 | abstraction layer and not make any assumptions about what kind of stdio | |
917 | is being used. | |
918 | ||
919 | For a complete description of the PerlIO abstraction, consult L<perlapio>. | |
920 | ||
8ebc5c01 | 921 | =head2 Putting a C value on Perl stack |
ce3d39e2 IZ |
922 | |
923 | A lot of opcodes (this is an elementary operation in the internal perl | |
924 | stack machine) put an SV* on the stack. However, as an optimization | |
925 | the corresponding SV is (usually) not recreated each time. The opcodes | |
926 | reuse specially assigned SVs (I<target>s) which are (as a corollary) | |
927 | not constantly freed/created. | |
928 | ||
0a753a76 | 929 | Each of the targets is created only once (but see |
ce3d39e2 IZ |
930 | L<Scratchpads and recursion> below), and when an opcode needs to put |
931 | an integer, a double, or a string on stack, it just sets the | |
932 | corresponding parts of its I<target> and puts the I<target> on stack. | |
933 | ||
934 | The macro to put this target on stack is C<PUSHTARG>, and it is | |
935 | directly used in some opcodes, as well as indirectly in zillions of | |
936 | others, which use it via C<(X)PUSH[pni]>. | |
937 | ||
8ebc5c01 | 938 | =head2 Scratchpads |
ce3d39e2 | 939 | |
5f05dabc | 940 | The question remains on when the SV's which are I<target>s for opcodes |
941 | are created. The answer is that they are created when the current unit -- | |
942 | a subroutine or a file (for opcodes for statements outside of | |
943 | subroutines) -- is compiled. During this time a special anonymous Perl | |
ce3d39e2 IZ |
944 | array is created, which is called a scratchpad for the current |
945 | unit. | |
946 | ||
5f05dabc | 947 | A scratchpad keeps SV's which are lexicals for the current unit and are |
ce3d39e2 IZ |
948 | targets for opcodes. One can deduce that an SV lives on a scratchpad |
949 | by looking on its flags: lexicals have C<SVs_PADMY> set, and | |
950 | I<target>s have C<SVs_PADTMP> set. | |
951 | ||
5f05dabc | 952 | The correspondence between OP's and I<target>s is not 1-to-1. Different |
953 | OP's in the compile tree of the unit can use the same target, if this | |
ce3d39e2 IZ |
954 | would not conflict with the expected life of the temporary. |
955 | ||
8ebc5c01 | 956 | =head2 Scratchpads and recursions |
ce3d39e2 IZ |
957 | |
958 | In fact it is not 100% true that a compiled unit contains a pointer to | |
959 | the scratchpad AV. In fact it contains a pointer to an AV of | |
960 | (initially) one element, and this element is the scratchpad AV. Why do | |
961 | we need an extra level of indirection? | |
962 | ||
963 | The answer is B<recursion>, and maybe (sometime soon) B<threads>. Both | |
964 | these can create several execution pointers going into the same | |
965 | subroutine. For the subroutine-child not write over the temporaries | |
966 | for the subroutine-parent (lifespan of which covers the call to the | |
967 | child), the parent and the child should have different | |
968 | scratchpads. (I<And> the lexicals should be separate anyway!) | |
969 | ||
5f05dabc | 970 | So each subroutine is born with an array of scratchpads (of length 1). |
971 | On each entry to the subroutine it is checked that the current | |
ce3d39e2 IZ |
972 | depth of the recursion is not more than the length of this array, and |
973 | if it is, new scratchpad is created and pushed into the array. | |
974 | ||
975 | The I<target>s on this scratchpad are C<undef>s, but they are already | |
976 | marked with correct flags. | |
977 | ||
0a753a76 | 978 | =head1 Compiled code |
979 | ||
980 | =head2 Code tree | |
981 | ||
982 | Here we describe the internal form your code is converted to by | |
983 | Perl. Start with a simple example: | |
984 | ||
985 | $a = $b + $c; | |
986 | ||
987 | This is converted to a tree similar to this one: | |
988 | ||
989 | assign-to | |
990 | / \ | |
991 | + $a | |
992 | / \ | |
993 | $b $c | |
994 | ||
995 | (but slightly more complicated). This tree reflect the way Perl | |
996 | parsed your code, but has nothing to do with the execution order. | |
997 | There is an additional "thread" going through the nodes of the tree | |
998 | which shows the order of execution of the nodes. In our simplified | |
999 | example above it looks like: | |
1000 | ||
1001 | $b ---> $c ---> + ---> $a ---> assign-to | |
1002 | ||
1003 | But with the actual compile tree for C<$a = $b + $c> it is different: | |
1004 | some nodes I<optimized away>. As a corollary, though the actual tree | |
1005 | contains more nodes than our simplified example, the execution order | |
1006 | is the same as in our example. | |
1007 | ||
1008 | =head2 Examining the tree | |
1009 | ||
1010 | If you have your perl compiled for debugging (usually done with C<-D | |
1011 | optimize=-g> on C<Configure> command line), you may examine the | |
1012 | compiled tree by specifying C<-Dx> on the Perl command line. The | |
1013 | output takes several lines per node, and for C<$b+$c> it looks like | |
1014 | this: | |
1015 | ||
1016 | 5 TYPE = add ===> 6 | |
1017 | TARG = 1 | |
1018 | FLAGS = (SCALAR,KIDS) | |
1019 | { | |
1020 | TYPE = null ===> (4) | |
1021 | (was rv2sv) | |
1022 | FLAGS = (SCALAR,KIDS) | |
1023 | { | |
1024 | 3 TYPE = gvsv ===> 4 | |
1025 | FLAGS = (SCALAR) | |
1026 | GV = main::b | |
1027 | } | |
1028 | } | |
1029 | { | |
1030 | TYPE = null ===> (5) | |
1031 | (was rv2sv) | |
1032 | FLAGS = (SCALAR,KIDS) | |
1033 | { | |
1034 | 4 TYPE = gvsv ===> 5 | |
1035 | FLAGS = (SCALAR) | |
1036 | GV = main::c | |
1037 | } | |
1038 | } | |
1039 | ||
1040 | This tree has 5 nodes (one per C<TYPE> specifier), only 3 of them are | |
1041 | not optimized away (one per number in the left column). The immediate | |
1042 | children of the given node correspond to C<{}> pairs on the same level | |
1043 | of indentation, thus this listing corresponds to the tree: | |
1044 | ||
1045 | add | |
1046 | / \ | |
1047 | null null | |
1048 | | | | |
1049 | gvsv gvsv | |
1050 | ||
1051 | The execution order is indicated by C<===E<gt>> marks, thus it is C<3 | |
1052 | 4 5 6> (node C<6> is not included into above listing), i.e., | |
1053 | C<gvsv gvsv add whatever>. | |
1054 | ||
1055 | =head2 Compile pass 1: check routines | |
1056 | ||
1057 | The tree is created by the I<pseudo-compiler> while yacc code feeds it | |
1058 | the constructions it recognizes. Since yacc works bottom-up, so does | |
1059 | the first pass of perl compilation. | |
1060 | ||
1061 | What makes this pass interesting for perl developers is that some | |
1062 | optimization may be performed on this pass. This is optimization by | |
1063 | so-called I<check routines>. The correspondence between node names | |
1064 | and corresponding check routines is described in F<opcode.pl> (do not | |
1065 | forget to run C<make regen_headers> if you modify this file). | |
1066 | ||
1067 | A check routine is called when the node is fully constructed except | |
1068 | for the execution-order thread. Since at this time there is no | |
1069 | back-links to the currently constructed node, one can do most any | |
1070 | operation to the top-level node, including freeing it and/or creating | |
1071 | new nodes above/below it. | |
1072 | ||
1073 | The check routine returns the node which should be inserted into the | |
1074 | tree (if the top-level node was not modified, check routine returns | |
1075 | its argument). | |
1076 | ||
1077 | By convention, check routines have names C<ck_*>. They are usually | |
1078 | called from C<new*OP> subroutines (or C<convert>) (which in turn are | |
1079 | called from F<perly.y>). | |
1080 | ||
1081 | =head2 Compile pass 1a: constant folding | |
1082 | ||
1083 | Immediately after the check routine is called the returned node is | |
1084 | checked for being compile-time executable. If it is (the value is | |
1085 | judged to be constant) it is immediately executed, and a I<constant> | |
1086 | node with the "return value" of the corresponding subtree is | |
1087 | substituted instead. The subtree is deleted. | |
1088 | ||
1089 | If constant folding was not performed, the execution-order thread is | |
1090 | created. | |
1091 | ||
1092 | =head2 Compile pass 2: context propagation | |
1093 | ||
1094 | When a context for a part of compile tree is known, it is propagated | |
1095 | down through the tree. Aat this time the context can have 5 values | |
1096 | (instead of 2 for runtime context): void, boolean, scalar, list, and | |
1097 | lvalue. In contrast with the pass 1 this pass is processed from top | |
1098 | to bottom: a node's context determines the context for its children. | |
1099 | ||
1100 | Additional context-dependent optimizations are performed at this time. | |
1101 | Since at this moment the compile tree contains back-references (via | |
1102 | "thread" pointers), nodes cannot be free()d now. To allow | |
1103 | optimized-away nodes at this stage, such nodes are null()ified instead | |
1104 | of free()ing (i.e. their type is changed to OP_NULL). | |
1105 | ||
1106 | =head2 Compile pass 3: peephole optimization | |
1107 | ||
1108 | After the compile tree for a subroutine (or for an C<eval> or a file) | |
1109 | is created, an additional pass over the code is performed. This pass | |
1110 | is neither top-down or bottom-up, but in the execution order (with | |
1111 | additional compilications for conditionals). These optimizations are | |
1112 | done in the subroutine peep(). Optimizations performed at this stage | |
1113 | are subject to the same restrictions as in the pass 2. | |
1114 | ||
1115 | =head1 API LISTING | |
a0d0e21e | 1116 | |
cb1a09d0 AD |
1117 | This is a listing of functions, macros, flags, and variables that may be |
1118 | useful to extension writers or that may be found while reading other | |
1119 | extensions. | |
a0d0e21e | 1120 | |
cb1a09d0 | 1121 | =over 8 |
a0d0e21e | 1122 | |
cb1a09d0 AD |
1123 | =item AvFILL |
1124 | ||
1125 | See C<av_len>. | |
1126 | ||
1127 | =item av_clear | |
1128 | ||
1129 | Clears an array, making it empty. | |
1130 | ||
1131 | void av_clear _((AV* ar)); | |
1132 | ||
1133 | =item av_extend | |
1134 | ||
1135 | Pre-extend an array. The C<key> is the index to which the array should be | |
1136 | extended. | |
1137 | ||
1138 | void av_extend _((AV* ar, I32 key)); | |
1139 | ||
1140 | =item av_fetch | |
1141 | ||
1142 | Returns the SV at the specified index in the array. The C<key> is the | |
1143 | index. If C<lval> is set then the fetch will be part of a store. Check | |
1144 | that the return value is non-null before dereferencing it to a C<SV*>. | |
1145 | ||
1146 | SV** av_fetch _((AV* ar, I32 key, I32 lval)); | |
1147 | ||
1148 | =item av_len | |
1149 | ||
1150 | Returns the highest index in the array. Returns -1 if the array is empty. | |
1151 | ||
1152 | I32 av_len _((AV* ar)); | |
1153 | ||
1154 | =item av_make | |
1155 | ||
5fb8527f | 1156 | Creates a new AV and populates it with a list of SVs. The SVs are copied |
1157 | into the array, so they may be freed after the call to av_make. The new AV | |
5f05dabc | 1158 | will have a reference count of 1. |
cb1a09d0 AD |
1159 | |
1160 | AV* av_make _((I32 size, SV** svp)); | |
1161 | ||
1162 | =item av_pop | |
1163 | ||
1164 | Pops an SV off the end of the array. Returns C<&sv_undef> if the array is | |
1165 | empty. | |
1166 | ||
1167 | SV* av_pop _((AV* ar)); | |
1168 | ||
1169 | =item av_push | |
1170 | ||
5fb8527f | 1171 | Pushes an SV onto the end of the array. The array will grow automatically |
1172 | to accommodate the addition. | |
cb1a09d0 AD |
1173 | |
1174 | void av_push _((AV* ar, SV* val)); | |
1175 | ||
1176 | =item av_shift | |
1177 | ||
1178 | Shifts an SV off the beginning of the array. | |
1179 | ||
1180 | SV* av_shift _((AV* ar)); | |
1181 | ||
1182 | =item av_store | |
1183 | ||
1184 | Stores an SV in an array. The array index is specified as C<key>. The | |
1185 | return value will be null if the operation failed, otherwise it can be | |
1186 | dereferenced to get the original C<SV*>. | |
1187 | ||
1188 | SV** av_store _((AV* ar, I32 key, SV* val)); | |
1189 | ||
1190 | =item av_undef | |
1191 | ||
1192 | Undefines the array. | |
1193 | ||
1194 | void av_undef _((AV* ar)); | |
1195 | ||
1196 | =item av_unshift | |
1197 | ||
5fb8527f | 1198 | Unshift an SV onto the beginning of the array. The array will grow |
1199 | automatically to accommodate the addition. | |
cb1a09d0 AD |
1200 | |
1201 | void av_unshift _((AV* ar, I32 num)); | |
1202 | ||
1203 | =item CLASS | |
1204 | ||
1205 | Variable which is setup by C<xsubpp> to indicate the class name for a C++ XS | |
5fb8527f | 1206 | constructor. This is always a C<char*>. See C<THIS> and |
1207 | L<perlxs/"Using XS With C++">. | |
cb1a09d0 AD |
1208 | |
1209 | =item Copy | |
1210 | ||
1211 | The XSUB-writer's interface to the C C<memcpy> function. The C<s> is the | |
1212 | source, C<d> is the destination, C<n> is the number of items, and C<t> is | |
1213 | the type. | |
1214 | ||
1215 | (void) Copy( s, d, n, t ); | |
1216 | ||
1217 | =item croak | |
1218 | ||
1219 | This is the XSUB-writer's interface to Perl's C<die> function. Use this | |
1220 | function the same way you use the C C<printf> function. See C<warn>. | |
1221 | ||
1222 | =item CvSTASH | |
1223 | ||
1224 | Returns the stash of the CV. | |
1225 | ||
1226 | HV * CvSTASH( SV* sv ) | |
1227 | ||
1228 | =item DBsingle | |
1229 | ||
1230 | When Perl is run in debugging mode, with the B<-d> switch, this SV is a | |
1231 | boolean which indicates whether subs are being single-stepped. | |
5fb8527f | 1232 | Single-stepping is automatically turned on after every step. This is the C |
1233 | variable which corresponds to Perl's $DB::single variable. See C<DBsub>. | |
cb1a09d0 AD |
1234 | |
1235 | =item DBsub | |
1236 | ||
1237 | When Perl is run in debugging mode, with the B<-d> switch, this GV contains | |
5fb8527f | 1238 | the SV which holds the name of the sub being debugged. This is the C |
1239 | variable which corresponds to Perl's $DB::sub variable. See C<DBsingle>. | |
cb1a09d0 AD |
1240 | The sub name can be found by |
1241 | ||
1242 | SvPV( GvSV( DBsub ), na ) | |
1243 | ||
5fb8527f | 1244 | =item DBtrace |
1245 | ||
1246 | Trace variable used when Perl is run in debugging mode, with the B<-d> | |
1247 | switch. This is the C variable which corresponds to Perl's $DB::trace | |
1248 | variable. See C<DBsingle>. | |
1249 | ||
cb1a09d0 AD |
1250 | =item dMARK |
1251 | ||
5fb8527f | 1252 | Declare a stack marker variable, C<mark>, for the XSUB. See C<MARK> and |
1253 | C<dORIGMARK>. | |
cb1a09d0 AD |
1254 | |
1255 | =item dORIGMARK | |
1256 | ||
1257 | Saves the original stack mark for the XSUB. See C<ORIGMARK>. | |
1258 | ||
5fb8527f | 1259 | =item dowarn |
1260 | ||
1261 | The C variable which corresponds to Perl's $^W warning variable. | |
1262 | ||
cb1a09d0 AD |
1263 | =item dSP |
1264 | ||
5fb8527f | 1265 | Declares a stack pointer variable, C<sp>, for the XSUB. See C<SP>. |
cb1a09d0 AD |
1266 | |
1267 | =item dXSARGS | |
1268 | ||
1269 | Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is | |
1270 | usually handled automatically by C<xsubpp>. Declares the C<items> variable | |
1271 | to indicate the number of items on the stack. | |
1272 | ||
5fb8527f | 1273 | =item dXSI32 |
1274 | ||
1275 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually | |
1276 | handled automatically by C<xsubpp>. | |
1277 | ||
1278 | =item dXSI32 | |
1279 | ||
1280 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually | |
1281 | handled automatically by C<xsubpp>. | |
1282 | ||
cb1a09d0 AD |
1283 | =item ENTER |
1284 | ||
1285 | Opening bracket on a callback. See C<LEAVE> and L<perlcall>. | |
1286 | ||
1287 | ENTER; | |
1288 | ||
1289 | =item EXTEND | |
1290 | ||
1291 | Used to extend the argument stack for an XSUB's return values. | |
1292 | ||
1293 | EXTEND( sp, int x ); | |
1294 | ||
1295 | =item FREETMPS | |
1296 | ||
1297 | Closing bracket for temporaries on a callback. See C<SAVETMPS> and | |
1298 | L<perlcall>. | |
1299 | ||
1300 | FREETMPS; | |
1301 | ||
1302 | =item G_ARRAY | |
1303 | ||
1304 | Used to indicate array context. See C<GIMME> and L<perlcall>. | |
1305 | ||
1306 | =item G_DISCARD | |
1307 | ||
1308 | Indicates that arguments returned from a callback should be discarded. See | |
1309 | L<perlcall>. | |
1310 | ||
1311 | =item G_EVAL | |
1312 | ||
1313 | Used to force a Perl C<eval> wrapper around a callback. See L<perlcall>. | |
1314 | ||
1315 | =item GIMME | |
1316 | ||
1317 | The XSUB-writer's equivalent to Perl's C<wantarray>. Returns C<G_SCALAR> or | |
1318 | C<G_ARRAY> for scalar or array context. | |
1319 | ||
1320 | =item G_NOARGS | |
1321 | ||
1322 | Indicates that no arguments are being sent to a callback. See L<perlcall>. | |
1323 | ||
1324 | =item G_SCALAR | |
1325 | ||
1326 | Used to indicate scalar context. See C<GIMME> and L<perlcall>. | |
1327 | ||
faed5253 JO |
1328 | =item gv_fetchmeth |
1329 | ||
1330 | Returns the glob with the given C<name> and a defined subroutine or | |
1331 | C<NULL>. The glob lives in the given C<stash>, or in the stashes accessable | |
1332 | via @ISA and @<UNIVERSAL>. | |
1333 | ||
0a753a76 | 1334 | The argument C<level> should be either 0 or -1. If C<level==0>, as a |
1335 | side-effect creates a glob with the given C<name> in the given | |
1336 | C<stash> which in the case of success contains an alias for the | |
1337 | subroutine, and sets up caching info for this glob. Similarly for all | |
1338 | the searched stashes. | |
1339 | ||
1340 | The GV returned from C<gv_fetchmeth> may be a method cache entry, | |
1341 | which is not visible to Perl code. So when calling C<perl_call_sv>, | |
1342 | you should not use the GV directly; instead, you should use the | |
1343 | method's CV, which can be obtained from the GV with the C<GvCV> macro. | |
faed5253 JO |
1344 | |
1345 | GV* gv_fetchmeth _((HV* stash, char* name, STRLEN len, I32 level)); | |
1346 | ||
1347 | =item gv_fetchmethod | |
1348 | ||
1349 | Returns the glob which contains the subroutine to call to invoke the | |
1350 | method on the C<stash>. In fact in the presense of autoloading this may | |
1351 | be the glob for "AUTOLOAD". In this case the corresponing variable | |
1352 | $AUTOLOAD is already setup. | |
1353 | ||
1354 | Note that if you want to keep this glob for a long time, you need to | |
1355 | check for it being "AUTOLOAD", since at the later time the the call | |
1356 | may load a different subroutine due to $AUTOLOAD changing its value. | |
1357 | Use the glob created via a side effect to do this. | |
1358 | ||
1359 | This function grants C<"SUPER"> token as prefix of name or postfix of | |
1360 | the stash name. | |
1361 | ||
0a753a76 | 1362 | Has the same side-effects and as C<gv_fetchmeth> with C<level==0>. |
1363 | C<name> should be writable if contains C<':'> or C<'\''>. | |
1364 | The warning against passing the GV returned by C<gv_fetchmeth> to | |
1365 | C<perl_call_sv> apply equally to C<gv_fetchmethod>. | |
faed5253 JO |
1366 | |
1367 | GV* gv_fetchmethod _((HV* stash, char* name)); | |
1368 | ||
cb1a09d0 AD |
1369 | =item gv_stashpv |
1370 | ||
1371 | Returns a pointer to the stash for a specified package. If C<create> is set | |
1372 | then the package will be created if it does not already exist. If C<create> | |
1373 | is not set and the package does not exist then NULL is returned. | |
1374 | ||
1375 | HV* gv_stashpv _((char* name, I32 create)); | |
1376 | ||
1377 | =item gv_stashsv | |
1378 | ||
1379 | Returns a pointer to the stash for a specified package. See C<gv_stashpv>. | |
1380 | ||
1381 | HV* gv_stashsv _((SV* sv, I32 create)); | |
1382 | ||
e5581bf4 | 1383 | =item GvSV |
cb1a09d0 | 1384 | |
e5581bf4 | 1385 | Return the SV from the GV. |
44a8e56a | 1386 | |
1387 | =item he_delayfree | |
1388 | ||
1389 | Releases a hash entry, such as while iterating though the hash, but | |
1390 | delays actual freeing of key and value until the end of the current | |
1391 | statement (or thereabouts) with C<sv_2mortal>. See C<hv_iternext>. | |
cb1a09d0 | 1392 | |
e5581bf4 JO |
1393 | void he_delayfree _((HV* hv, HE* hent)); |
1394 | ||
1395 | =item he_free | |
1396 | ||
1397 | Releases a hash entry, such as while iterating though the hash. See | |
1398 | C<hv_iternext>. | |
1399 | ||
1400 | void he_free _((HV* hv, HE* hent)); | |
cb1a09d0 AD |
1401 | |
1402 | =item hv_clear | |
1403 | ||
1404 | Clears a hash, making it empty. | |
1405 | ||
1406 | void hv_clear _((HV* tb)); | |
1407 | ||
1408 | =item hv_delete | |
1409 | ||
1410 | Deletes a key/value pair in the hash. The value SV is removed from the hash | |
5fb8527f | 1411 | and returned to the caller. The C<klen> is the length of the key. The |
cb1a09d0 AD |
1412 | C<flags> value will normally be zero; if set to G_DISCARD then null will be |
1413 | returned. | |
1414 | ||
1415 | SV* hv_delete _((HV* tb, char* key, U32 klen, I32 flags)); | |
1416 | ||
1417 | =item hv_exists | |
1418 | ||
1419 | Returns a boolean indicating whether the specified hash key exists. The | |
5fb8527f | 1420 | C<klen> is the length of the key. |
cb1a09d0 AD |
1421 | |
1422 | bool hv_exists _((HV* tb, char* key, U32 klen)); | |
1423 | ||
1424 | =item hv_fetch | |
1425 | ||
1426 | Returns the SV which corresponds to the specified key in the hash. The | |
5fb8527f | 1427 | C<klen> is the length of the key. If C<lval> is set then the fetch will be |
cb1a09d0 AD |
1428 | part of a store. Check that the return value is non-null before |
1429 | dereferencing it to a C<SV*>. | |
1430 | ||
1431 | SV** hv_fetch _((HV* tb, char* key, U32 klen, I32 lval)); | |
1432 | ||
1433 | =item hv_iterinit | |
1434 | ||
1435 | Prepares a starting point to traverse a hash table. | |
1436 | ||
1437 | I32 hv_iterinit _((HV* tb)); | |
1438 | ||
1439 | =item hv_iterkey | |
1440 | ||
1441 | Returns the key from the current position of the hash iterator. See | |
1442 | C<hv_iterinit>. | |
1443 | ||
1444 | char* hv_iterkey _((HE* entry, I32* retlen)); | |
1445 | ||
1446 | =item hv_iternext | |
1447 | ||
1448 | Returns entries from a hash iterator. See C<hv_iterinit>. | |
1449 | ||
1450 | HE* hv_iternext _((HV* tb)); | |
1451 | ||
1452 | =item hv_iternextsv | |
1453 | ||
1454 | Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one | |
1455 | operation. | |
1456 | ||
1457 | SV * hv_iternextsv _((HV* hv, char** key, I32* retlen)); | |
1458 | ||
1459 | =item hv_iterval | |
1460 | ||
1461 | Returns the value from the current position of the hash iterator. See | |
1462 | C<hv_iterkey>. | |
1463 | ||
1464 | SV* hv_iterval _((HV* tb, HE* entry)); | |
1465 | ||
1466 | =item hv_magic | |
1467 | ||
1468 | Adds magic to a hash. See C<sv_magic>. | |
1469 | ||
1470 | void hv_magic _((HV* hv, GV* gv, int how)); | |
1471 | ||
1472 | =item HvNAME | |
1473 | ||
1474 | Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>. | |
1475 | ||
1476 | char *HvNAME (HV* stash) | |
1477 | ||
1478 | =item hv_store | |
1479 | ||
1480 | Stores an SV in a hash. The hash key is specified as C<key> and C<klen> is | |
1481 | the length of the key. The C<hash> parameter is the pre-computed hash | |
1482 | value; if it is zero then Perl will compute it. The return value will be | |
1483 | null if the operation failed, otherwise it can be dereferenced to get the | |
1484 | original C<SV*>. | |
1485 | ||
1486 | SV** hv_store _((HV* tb, char* key, U32 klen, SV* val, U32 hash)); | |
1487 | ||
1488 | =item hv_undef | |
1489 | ||
1490 | Undefines the hash. | |
1491 | ||
1492 | void hv_undef _((HV* tb)); | |
1493 | ||
1494 | =item isALNUM | |
1495 | ||
1496 | Returns a boolean indicating whether the C C<char> is an ascii alphanumeric | |
5f05dabc | 1497 | character or digit. |
cb1a09d0 AD |
1498 | |
1499 | int isALNUM (char c) | |
1500 | ||
1501 | =item isALPHA | |
1502 | ||
5fb8527f | 1503 | Returns a boolean indicating whether the C C<char> is an ascii alphabetic |
cb1a09d0 AD |
1504 | character. |
1505 | ||
1506 | int isALPHA (char c) | |
1507 | ||
1508 | =item isDIGIT | |
1509 | ||
1510 | Returns a boolean indicating whether the C C<char> is an ascii digit. | |
1511 | ||
1512 | int isDIGIT (char c) | |
1513 | ||
1514 | =item isLOWER | |
1515 | ||
1516 | Returns a boolean indicating whether the C C<char> is a lowercase character. | |
1517 | ||
1518 | int isLOWER (char c) | |
1519 | ||
1520 | =item isSPACE | |
1521 | ||
1522 | Returns a boolean indicating whether the C C<char> is whitespace. | |
1523 | ||
1524 | int isSPACE (char c) | |
1525 | ||
1526 | =item isUPPER | |
1527 | ||
1528 | Returns a boolean indicating whether the C C<char> is an uppercase character. | |
1529 | ||
1530 | int isUPPER (char c) | |
1531 | ||
1532 | =item items | |
1533 | ||
1534 | Variable which is setup by C<xsubpp> to indicate the number of items on the | |
5fb8527f | 1535 | stack. See L<perlxs/"Variable-length Parameter Lists">. |
1536 | ||
1537 | =item ix | |
1538 | ||
1539 | Variable which is setup by C<xsubpp> to indicate which of an XSUB's aliases | |
1540 | was used to invoke it. See L<perlxs/"The ALIAS: Keyword">. | |
cb1a09d0 AD |
1541 | |
1542 | =item LEAVE | |
1543 | ||
1544 | Closing bracket on a callback. See C<ENTER> and L<perlcall>. | |
1545 | ||
1546 | LEAVE; | |
1547 | ||
1548 | =item MARK | |
1549 | ||
5fb8527f | 1550 | Stack marker variable for the XSUB. See C<dMARK>. |
cb1a09d0 AD |
1551 | |
1552 | =item mg_clear | |
1553 | ||
1554 | Clear something magical that the SV represents. See C<sv_magic>. | |
1555 | ||
1556 | int mg_clear _((SV* sv)); | |
1557 | ||
1558 | =item mg_copy | |
1559 | ||
1560 | Copies the magic from one SV to another. See C<sv_magic>. | |
1561 | ||
1562 | int mg_copy _((SV *, SV *, char *, STRLEN)); | |
1563 | ||
1564 | =item mg_find | |
1565 | ||
1566 | Finds the magic pointer for type matching the SV. See C<sv_magic>. | |
1567 | ||
1568 | MAGIC* mg_find _((SV* sv, int type)); | |
1569 | ||
1570 | =item mg_free | |
1571 | ||
1572 | Free any magic storage used by the SV. See C<sv_magic>. | |
1573 | ||
1574 | int mg_free _((SV* sv)); | |
1575 | ||
1576 | =item mg_get | |
1577 | ||
1578 | Do magic after a value is retrieved from the SV. See C<sv_magic>. | |
1579 | ||
1580 | int mg_get _((SV* sv)); | |
1581 | ||
1582 | =item mg_len | |
1583 | ||
1584 | Report on the SV's length. See C<sv_magic>. | |
1585 | ||
1586 | U32 mg_len _((SV* sv)); | |
1587 | ||
1588 | =item mg_magical | |
1589 | ||
1590 | Turns on the magical status of an SV. See C<sv_magic>. | |
1591 | ||
1592 | void mg_magical _((SV* sv)); | |
1593 | ||
1594 | =item mg_set | |
1595 | ||
1596 | Do magic after a value is assigned to the SV. See C<sv_magic>. | |
1597 | ||
1598 | int mg_set _((SV* sv)); | |
1599 | ||
1600 | =item Move | |
1601 | ||
1602 | The XSUB-writer's interface to the C C<memmove> function. The C<s> is the | |
1603 | source, C<d> is the destination, C<n> is the number of items, and C<t> is | |
1604 | the type. | |
1605 | ||
1606 | (void) Move( s, d, n, t ); | |
1607 | ||
1608 | =item na | |
1609 | ||
1610 | A variable which may be used with C<SvPV> to tell Perl to calculate the | |
1611 | string length. | |
1612 | ||
1613 | =item New | |
1614 | ||
1615 | The XSUB-writer's interface to the C C<malloc> function. | |
1616 | ||
1617 | void * New( x, void *ptr, int size, type ) | |
1618 | ||
1619 | =item Newc | |
1620 | ||
1621 | The XSUB-writer's interface to the C C<malloc> function, with cast. | |
1622 | ||
1623 | void * Newc( x, void *ptr, int size, type, cast ) | |
1624 | ||
1625 | =item Newz | |
1626 | ||
1627 | The XSUB-writer's interface to the C C<malloc> function. The allocated | |
1628 | memory is zeroed with C<memzero>. | |
1629 | ||
1630 | void * Newz( x, void *ptr, int size, type ) | |
1631 | ||
1632 | =item newAV | |
1633 | ||
5f05dabc | 1634 | Creates a new AV. The reference count is set to 1. |
cb1a09d0 AD |
1635 | |
1636 | AV* newAV _((void)); | |
1637 | ||
1638 | =item newHV | |
1639 | ||
5f05dabc | 1640 | Creates a new HV. The reference count is set to 1. |
cb1a09d0 AD |
1641 | |
1642 | HV* newHV _((void)); | |
1643 | ||
5f05dabc | 1644 | =item newRV_inc |
cb1a09d0 | 1645 | |
5f05dabc | 1646 | Creates an RV wrapper for an SV. The reference count for the original SV is |
cb1a09d0 AD |
1647 | incremented. |
1648 | ||
5f05dabc | 1649 | SV* newRV_inc _((SV* ref)); |
1650 | ||
1651 | For historical reasons, "newRV" is a synonym for "newRV_inc". | |
1652 | ||
1653 | =item newRV_noinc | |
1654 | ||
1655 | Creates an RV wrapper for an SV. The reference count for the original | |
1656 | SV is B<not> incremented. | |
1657 | ||
07fa94a1 | 1658 | SV* newRV_noinc _((SV* ref)); |
cb1a09d0 AD |
1659 | |
1660 | =item newSV | |
1661 | ||
1662 | Creates a new SV. The C<len> parameter indicates the number of bytes of | |
07fa94a1 JO |
1663 | pre-allocated string space the SV should have. The reference count for the |
1664 | new SV is set to 1. | |
cb1a09d0 AD |
1665 | |
1666 | SV* newSV _((STRLEN len)); | |
1667 | ||
1668 | =item newSViv | |
1669 | ||
07fa94a1 JO |
1670 | Creates a new SV and copies an integer into it. The reference count for the |
1671 | SV is set to 1. | |
cb1a09d0 AD |
1672 | |
1673 | SV* newSViv _((IV i)); | |
1674 | ||
1675 | =item newSVnv | |
1676 | ||
07fa94a1 JO |
1677 | Creates a new SV and copies a double into it. The reference count for the |
1678 | SV is set to 1. | |
cb1a09d0 AD |
1679 | |
1680 | SV* newSVnv _((NV i)); | |
1681 | ||
1682 | =item newSVpv | |
1683 | ||
07fa94a1 JO |
1684 | Creates a new SV and copies a string into it. The reference count for the |
1685 | SV is set to 1. If C<len> is zero then Perl will compute the length. | |
cb1a09d0 AD |
1686 | |
1687 | SV* newSVpv _((char* s, STRLEN len)); | |
1688 | ||
1689 | =item newSVrv | |
1690 | ||
1691 | Creates a new SV for the RV, C<rv>, to point to. If C<rv> is not an RV then | |
5fb8527f | 1692 | it will be upgraded to one. If C<classname> is non-null then the new SV will |
cb1a09d0 | 1693 | be blessed in the specified package. The new SV is returned and its |
5f05dabc | 1694 | reference count is 1. |
8ebc5c01 | 1695 | |
cb1a09d0 AD |
1696 | SV* newSVrv _((SV* rv, char* classname)); |
1697 | ||
1698 | =item newSVsv | |
1699 | ||
5fb8527f | 1700 | Creates a new SV which is an exact duplicate of the original SV. |
cb1a09d0 AD |
1701 | |
1702 | SV* newSVsv _((SV* old)); | |
1703 | ||
1704 | =item newXS | |
1705 | ||
1706 | Used by C<xsubpp> to hook up XSUBs as Perl subs. | |
1707 | ||
1708 | =item newXSproto | |
1709 | ||
1710 | Used by C<xsubpp> to hook up XSUBs as Perl subs. Adds Perl prototypes to | |
1711 | the subs. | |
1712 | ||
1713 | =item Nullav | |
1714 | ||
1715 | Null AV pointer. | |
1716 | ||
1717 | =item Nullch | |
1718 | ||
1719 | Null character pointer. | |
1720 | ||
1721 | =item Nullcv | |
1722 | ||
1723 | Null CV pointer. | |
1724 | ||
1725 | =item Nullhv | |
1726 | ||
1727 | Null HV pointer. | |
1728 | ||
1729 | =item Nullsv | |
1730 | ||
1731 | Null SV pointer. | |
1732 | ||
1733 | =item ORIGMARK | |
1734 | ||
1735 | The original stack mark for the XSUB. See C<dORIGMARK>. | |
1736 | ||
1737 | =item perl_alloc | |
1738 | ||
1739 | Allocates a new Perl interpreter. See L<perlembed>. | |
1740 | ||
1741 | =item perl_call_argv | |
1742 | ||
1743 | Performs a callback to the specified Perl sub. See L<perlcall>. | |
1744 | ||
1745 | I32 perl_call_argv _((char* subname, I32 flags, char** argv)); | |
1746 | ||
1747 | =item perl_call_method | |
1748 | ||
1749 | Performs a callback to the specified Perl method. The blessed object must | |
1750 | be on the stack. See L<perlcall>. | |
1751 | ||
1752 | I32 perl_call_method _((char* methname, I32 flags)); | |
1753 | ||
1754 | =item perl_call_pv | |
1755 | ||
1756 | Performs a callback to the specified Perl sub. See L<perlcall>. | |
1757 | ||
1758 | I32 perl_call_pv _((char* subname, I32 flags)); | |
1759 | ||
1760 | =item perl_call_sv | |
1761 | ||
1762 | Performs a callback to the Perl sub whose name is in the SV. See | |
1763 | L<perlcall>. | |
1764 | ||
1765 | I32 perl_call_sv _((SV* sv, I32 flags)); | |
1766 | ||
1767 | =item perl_construct | |
1768 | ||
1769 | Initializes a new Perl interpreter. See L<perlembed>. | |
1770 | ||
1771 | =item perl_destruct | |
1772 | ||
1773 | Shuts down a Perl interpreter. See L<perlembed>. | |
1774 | ||
1775 | =item perl_eval_sv | |
1776 | ||
1777 | Tells Perl to C<eval> the string in the SV. | |
1778 | ||
1779 | I32 perl_eval_sv _((SV* sv, I32 flags)); | |
1780 | ||
1781 | =item perl_free | |
1782 | ||
1783 | Releases a Perl interpreter. See L<perlembed>. | |
1784 | ||
1785 | =item perl_get_av | |
1786 | ||
1787 | Returns the AV of the specified Perl array. If C<create> is set and the | |
1788 | Perl variable does not exist then it will be created. If C<create> is not | |
1789 | set and the variable does not exist then null is returned. | |
1790 | ||
1791 | AV* perl_get_av _((char* name, I32 create)); | |
1792 | ||
1793 | =item perl_get_cv | |
1794 | ||
1795 | Returns the CV of the specified Perl sub. If C<create> is set and the Perl | |
1796 | variable does not exist then it will be created. If C<create> is not | |
1797 | set and the variable does not exist then null is returned. | |
1798 | ||
1799 | CV* perl_get_cv _((char* name, I32 create)); | |
1800 | ||
1801 | =item perl_get_hv | |
1802 | ||
1803 | Returns the HV of the specified Perl hash. If C<create> is set and the Perl | |
1804 | variable does not exist then it will be created. If C<create> is not | |
1805 | set and the variable does not exist then null is returned. | |
1806 | ||
1807 | HV* perl_get_hv _((char* name, I32 create)); | |
1808 | ||
1809 | =item perl_get_sv | |
1810 | ||
1811 | Returns the SV of the specified Perl scalar. If C<create> is set and the | |
1812 | Perl variable does not exist then it will be created. If C<create> is not | |
1813 | set and the variable does not exist then null is returned. | |
1814 | ||
1815 | SV* perl_get_sv _((char* name, I32 create)); | |
1816 | ||
1817 | =item perl_parse | |
1818 | ||
1819 | Tells a Perl interpreter to parse a Perl script. See L<perlembed>. | |
1820 | ||
1821 | =item perl_require_pv | |
1822 | ||
1823 | Tells Perl to C<require> a module. | |
1824 | ||
1825 | void perl_require_pv _((char* pv)); | |
1826 | ||
1827 | =item perl_run | |
1828 | ||
1829 | Tells a Perl interpreter to run. See L<perlembed>. | |
1830 | ||
1831 | =item POPi | |
1832 | ||
1833 | Pops an integer off the stack. | |
1834 | ||
1835 | int POPi(); | |
1836 | ||
1837 | =item POPl | |
1838 | ||
1839 | Pops a long off the stack. | |
1840 | ||
1841 | long POPl(); | |
1842 | ||
1843 | =item POPp | |
1844 | ||
1845 | Pops a string off the stack. | |
1846 | ||
1847 | char * POPp(); | |
1848 | ||
1849 | =item POPn | |
1850 | ||
1851 | Pops a double off the stack. | |
1852 | ||
1853 | double POPn(); | |
1854 | ||
1855 | =item POPs | |
1856 | ||
1857 | Pops an SV off the stack. | |
1858 | ||
1859 | SV* POPs(); | |
1860 | ||
1861 | =item PUSHMARK | |
1862 | ||
1863 | Opening bracket for arguments on a callback. See C<PUTBACK> and L<perlcall>. | |
1864 | ||
1865 | PUSHMARK(p) | |
1866 | ||
1867 | =item PUSHi | |
1868 | ||
1869 | Push an integer onto the stack. The stack must have room for this element. | |
1870 | See C<XPUSHi>. | |
1871 | ||
1872 | PUSHi(int d) | |
1873 | ||
1874 | =item PUSHn | |
1875 | ||
1876 | Push a double onto the stack. The stack must have room for this element. | |
1877 | See C<XPUSHn>. | |
1878 | ||
1879 | PUSHn(double d) | |
1880 | ||
1881 | =item PUSHp | |
1882 | ||
1883 | Push a string onto the stack. The stack must have room for this element. | |
1884 | The C<len> indicates the length of the string. See C<XPUSHp>. | |
1885 | ||
1886 | PUSHp(char *c, int len ) | |
1887 | ||
1888 | =item PUSHs | |
1889 | ||
1890 | Push an SV onto the stack. The stack must have room for this element. See | |
1891 | C<XPUSHs>. | |
1892 | ||
1893 | PUSHs(sv) | |
1894 | ||
1895 | =item PUTBACK | |
1896 | ||
1897 | Closing bracket for XSUB arguments. This is usually handled by C<xsubpp>. | |
1898 | See C<PUSHMARK> and L<perlcall> for other uses. | |
1899 | ||
1900 | PUTBACK; | |
1901 | ||
1902 | =item Renew | |
1903 | ||
1904 | The XSUB-writer's interface to the C C<realloc> function. | |
1905 | ||
1906 | void * Renew( void *ptr, int size, type ) | |
1907 | ||
1908 | =item Renewc | |
1909 | ||
1910 | The XSUB-writer's interface to the C C<realloc> function, with cast. | |
1911 | ||
1912 | void * Renewc( void *ptr, int size, type, cast ) | |
1913 | ||
1914 | =item RETVAL | |
1915 | ||
1916 | Variable which is setup by C<xsubpp> to hold the return value for an XSUB. | |
5fb8527f | 1917 | This is always the proper type for the XSUB. |
1918 | See L<perlxs/"The RETVAL Variable">. | |
cb1a09d0 AD |
1919 | |
1920 | =item safefree | |
1921 | ||
1922 | The XSUB-writer's interface to the C C<free> function. | |
1923 | ||
1924 | =item safemalloc | |
1925 | ||
1926 | The XSUB-writer's interface to the C C<malloc> function. | |
1927 | ||
1928 | =item saferealloc | |
1929 | ||
1930 | The XSUB-writer's interface to the C C<realloc> function. | |
1931 | ||
1932 | =item savepv | |
1933 | ||
1934 | Copy a string to a safe spot. This does not use an SV. | |
1935 | ||
1936 | char* savepv _((char* sv)); | |
1937 | ||
1938 | =item savepvn | |
1939 | ||
1940 | Copy a string to a safe spot. The C<len> indicates number of bytes to | |
1941 | copy. This does not use an SV. | |
1942 | ||
1943 | char* savepvn _((char* sv, I32 len)); | |
1944 | ||
1945 | =item SAVETMPS | |
1946 | ||
1947 | Opening bracket for temporaries on a callback. See C<FREETMPS> and | |
1948 | L<perlcall>. | |
1949 | ||
1950 | SAVETMPS; | |
1951 | ||
1952 | =item SP | |
1953 | ||
1954 | Stack pointer. This is usually handled by C<xsubpp>. See C<dSP> and | |
1955 | C<SPAGAIN>. | |
1956 | ||
1957 | =item SPAGAIN | |
1958 | ||
5f05dabc | 1959 | Re-fetch the stack pointer. Used after a callback. See L<perlcall>. |
cb1a09d0 AD |
1960 | |
1961 | SPAGAIN; | |
1962 | ||
1963 | =item ST | |
1964 | ||
1965 | Used to access elements on the XSUB's stack. | |
1966 | ||
1967 | SV* ST(int x) | |
1968 | ||
1969 | =item strEQ | |
1970 | ||
1971 | Test two strings to see if they are equal. Returns true or false. | |
1972 | ||
1973 | int strEQ( char *s1, char *s2 ) | |
1974 | ||
1975 | =item strGE | |
1976 | ||
1977 | Test two strings to see if the first, C<s1>, is greater than or equal to the | |
1978 | second, C<s2>. Returns true or false. | |
1979 | ||
1980 | int strGE( char *s1, char *s2 ) | |
1981 | ||
1982 | =item strGT | |
1983 | ||
1984 | Test two strings to see if the first, C<s1>, is greater than the second, | |
1985 | C<s2>. Returns true or false. | |
1986 | ||
1987 | int strGT( char *s1, char *s2 ) | |
1988 | ||
1989 | =item strLE | |
1990 | ||
1991 | Test two strings to see if the first, C<s1>, is less than or equal to the | |
1992 | second, C<s2>. Returns true or false. | |
1993 | ||
1994 | int strLE( char *s1, char *s2 ) | |
1995 | ||
1996 | =item strLT | |
1997 | ||
1998 | Test two strings to see if the first, C<s1>, is less than the second, | |
1999 | C<s2>. Returns true or false. | |
2000 | ||
2001 | int strLT( char *s1, char *s2 ) | |
2002 | ||
2003 | =item strNE | |
2004 | ||
2005 | Test two strings to see if they are different. Returns true or false. | |
2006 | ||
2007 | int strNE( char *s1, char *s2 ) | |
2008 | ||
2009 | =item strnEQ | |
2010 | ||
2011 | Test two strings to see if they are equal. The C<len> parameter indicates | |
2012 | the number of bytes to compare. Returns true or false. | |
2013 | ||
2014 | int strnEQ( char *s1, char *s2 ) | |
2015 | ||
2016 | =item strnNE | |
2017 | ||
2018 | Test two strings to see if they are different. The C<len> parameter | |
2019 | indicates the number of bytes to compare. Returns true or false. | |
2020 | ||
2021 | int strnNE( char *s1, char *s2, int len ) | |
2022 | ||
2023 | =item sv_2mortal | |
2024 | ||
2025 | Marks an SV as mortal. The SV will be destroyed when the current context | |
2026 | ends. | |
2027 | ||
2028 | SV* sv_2mortal _((SV* sv)); | |
2029 | ||
2030 | =item sv_bless | |
2031 | ||
2032 | Blesses an SV into a specified package. The SV must be an RV. The package | |
07fa94a1 JO |
2033 | must be designated by its stash (see C<gv_stashpv()>). The reference count |
2034 | of the SV is unaffected. | |
cb1a09d0 AD |
2035 | |
2036 | SV* sv_bless _((SV* sv, HV* stash)); | |
2037 | ||
2038 | =item sv_catpv | |
2039 | ||
2040 | Concatenates the string onto the end of the string which is in the SV. | |
2041 | ||
2042 | void sv_catpv _((SV* sv, char* ptr)); | |
2043 | ||
2044 | =item sv_catpvn | |
2045 | ||
2046 | Concatenates the string onto the end of the string which is in the SV. The | |
2047 | C<len> indicates number of bytes to copy. | |
2048 | ||
2049 | void sv_catpvn _((SV* sv, char* ptr, STRLEN len)); | |
2050 | ||
2051 | =item sv_catsv | |
2052 | ||
5fb8527f | 2053 | Concatenates the string from SV C<ssv> onto the end of the string in SV |
cb1a09d0 AD |
2054 | C<dsv>. |
2055 | ||
2056 | void sv_catsv _((SV* dsv, SV* ssv)); | |
2057 | ||
5fb8527f | 2058 | =item sv_cmp |
2059 | ||
2060 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the | |
2061 | string in C<sv1> is less than, equal to, or greater than the string in | |
2062 | C<sv2>. | |
2063 | ||
2064 | I32 sv_cmp _((SV* sv1, SV* sv2)); | |
2065 | ||
2066 | =item sv_cmp | |
2067 | ||
2068 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the | |
2069 | string in C<sv1> is less than, equal to, or greater than the string in | |
2070 | C<sv2>. | |
2071 | ||
2072 | I32 sv_cmp _((SV* sv1, SV* sv2)); | |
2073 | ||
cb1a09d0 AD |
2074 | =item SvCUR |
2075 | ||
2076 | Returns the length of the string which is in the SV. See C<SvLEN>. | |
2077 | ||
2078 | int SvCUR (SV* sv) | |
2079 | ||
2080 | =item SvCUR_set | |
2081 | ||
2082 | Set the length of the string which is in the SV. See C<SvCUR>. | |
2083 | ||
2084 | SvCUR_set (SV* sv, int val ) | |
2085 | ||
5fb8527f | 2086 | =item sv_dec |
2087 | ||
5f05dabc | 2088 | Auto-decrement of the value in the SV. |
5fb8527f | 2089 | |
2090 | void sv_dec _((SV* sv)); | |
2091 | ||
2092 | =item sv_dec | |
2093 | ||
5f05dabc | 2094 | Auto-decrement of the value in the SV. |
5fb8527f | 2095 | |
2096 | void sv_dec _((SV* sv)); | |
2097 | ||
cb1a09d0 AD |
2098 | =item SvEND |
2099 | ||
2100 | Returns a pointer to the last character in the string which is in the SV. | |
2101 | See C<SvCUR>. Access the character as | |
2102 | ||
2103 | *SvEND(sv) | |
2104 | ||
5fb8527f | 2105 | =item sv_eq |
2106 | ||
2107 | Returns a boolean indicating whether the strings in the two SVs are | |
2108 | identical. | |
2109 | ||
2110 | I32 sv_eq _((SV* sv1, SV* sv2)); | |
2111 | ||
cb1a09d0 AD |
2112 | =item SvGROW |
2113 | ||
5fb8527f | 2114 | Expands the character buffer in the SV. Calls C<sv_grow> to perform the |
2115 | expansion if necessary. Returns a pointer to the character buffer. | |
cb1a09d0 AD |
2116 | |
2117 | char * SvGROW( SV* sv, int len ) | |
2118 | ||
5fb8527f | 2119 | =item sv_grow |
2120 | ||
2121 | Expands the character buffer in the SV. This will use C<sv_unref> and will | |
2122 | upgrade the SV to C<SVt_PV>. Returns a pointer to the character buffer. | |
2123 | Use C<SvGROW>. | |
2124 | ||
2125 | =item sv_inc | |
2126 | ||
07fa94a1 | 2127 | Auto-increment of the value in the SV. |
5fb8527f | 2128 | |
2129 | void sv_inc _((SV* sv)); | |
2130 | ||
cb1a09d0 AD |
2131 | =item SvIOK |
2132 | ||
2133 | Returns a boolean indicating whether the SV contains an integer. | |
2134 | ||
2135 | int SvIOK (SV* SV) | |
2136 | ||
2137 | =item SvIOK_off | |
2138 | ||
2139 | Unsets the IV status of an SV. | |
2140 | ||
2141 | SvIOK_off (SV* sv) | |
2142 | ||
2143 | =item SvIOK_on | |
2144 | ||
2145 | Tells an SV that it is an integer. | |
2146 | ||
2147 | SvIOK_on (SV* sv) | |
2148 | ||
5fb8527f | 2149 | =item SvIOK_only |
2150 | ||
2151 | Tells an SV that it is an integer and disables all other OK bits. | |
2152 | ||
2153 | SvIOK_on (SV* sv) | |
2154 | ||
2155 | =item SvIOK_only | |
2156 | ||
2157 | Tells an SV that it is an integer and disables all other OK bits. | |
2158 | ||
2159 | SvIOK_on (SV* sv) | |
2160 | ||
cb1a09d0 AD |
2161 | =item SvIOKp |
2162 | ||
2163 | Returns a boolean indicating whether the SV contains an integer. Checks the | |
2164 | B<private> setting. Use C<SvIOK>. | |
2165 | ||
2166 | int SvIOKp (SV* SV) | |
2167 | ||
2168 | =item sv_isa | |
2169 | ||
2170 | Returns a boolean indicating whether the SV is blessed into the specified | |
2171 | class. This does not know how to check for subtype, so it doesn't work in | |
2172 | an inheritance relationship. | |
2173 | ||
2174 | int sv_isa _((SV* sv, char* name)); | |
2175 | ||
2176 | =item SvIV | |
2177 | ||
2178 | Returns the integer which is in the SV. | |
2179 | ||
2180 | int SvIV (SV* sv) | |
2181 | ||
2182 | =item sv_isobject | |
2183 | ||
2184 | Returns a boolean indicating whether the SV is an RV pointing to a blessed | |
2185 | object. If the SV is not an RV, or if the object is not blessed, then this | |
2186 | will return false. | |
2187 | ||
2188 | int sv_isobject _((SV* sv)); | |
2189 | ||
2190 | =item SvIVX | |
2191 | ||
2192 | Returns the integer which is stored in the SV. | |
2193 | ||
2194 | int SvIVX (SV* sv); | |
2195 | ||
2196 | =item SvLEN | |
2197 | ||
2198 | Returns the size of the string buffer in the SV. See C<SvCUR>. | |
2199 | ||
2200 | int SvLEN (SV* sv) | |
2201 | ||
5fb8527f | 2202 | =item sv_len |
2203 | ||
2204 | Returns the length of the string in the SV. Use C<SvCUR>. | |
2205 | ||
2206 | STRLEN sv_len _((SV* sv)); | |
2207 | ||
2208 | =item sv_len | |
2209 | ||
2210 | Returns the length of the string in the SV. Use C<SvCUR>. | |
2211 | ||
2212 | STRLEN sv_len _((SV* sv)); | |
2213 | ||
cb1a09d0 AD |
2214 | =item sv_magic |
2215 | ||
2216 | Adds magic to an SV. | |
2217 | ||
2218 | void sv_magic _((SV* sv, SV* obj, int how, char* name, I32 namlen)); | |
2219 | ||
2220 | =item sv_mortalcopy | |
2221 | ||
2222 | Creates a new SV which is a copy of the original SV. The new SV is marked | |
5f05dabc | 2223 | as mortal. |
cb1a09d0 AD |
2224 | |
2225 | SV* sv_mortalcopy _((SV* oldsv)); | |
2226 | ||
2227 | =item SvOK | |
2228 | ||
2229 | Returns a boolean indicating whether the value is an SV. | |
2230 | ||
2231 | int SvOK (SV* sv) | |
2232 | ||
2233 | =item sv_newmortal | |
2234 | ||
5f05dabc | 2235 | Creates a new SV which is mortal. The reference count of the SV is set to 1. |
cb1a09d0 AD |
2236 | |
2237 | SV* sv_newmortal _((void)); | |
2238 | ||
2239 | =item sv_no | |
2240 | ||
2241 | This is the C<false> SV. See C<sv_yes>. Always refer to this as C<&sv_no>. | |
2242 | ||
2243 | =item SvNIOK | |
2244 | ||
2245 | Returns a boolean indicating whether the SV contains a number, integer or | |
2246 | double. | |
2247 | ||
2248 | int SvNIOK (SV* SV) | |
2249 | ||
2250 | =item SvNIOK_off | |
2251 | ||
2252 | Unsets the NV/IV status of an SV. | |
2253 | ||
2254 | SvNIOK_off (SV* sv) | |
2255 | ||
2256 | =item SvNIOKp | |
2257 | ||
2258 | Returns a boolean indicating whether the SV contains a number, integer or | |
2259 | double. Checks the B<private> setting. Use C<SvNIOK>. | |
2260 | ||
2261 | int SvNIOKp (SV* SV) | |
2262 | ||
2263 | =item SvNOK | |
2264 | ||
2265 | Returns a boolean indicating whether the SV contains a double. | |
2266 | ||
2267 | int SvNOK (SV* SV) | |
2268 | ||
2269 | =item SvNOK_off | |
2270 | ||
2271 | Unsets the NV status of an SV. | |
2272 | ||
2273 | SvNOK_off (SV* sv) | |
2274 | ||
2275 | =item SvNOK_on | |
2276 | ||
2277 | Tells an SV that it is a double. | |
2278 | ||
2279 | SvNOK_on (SV* sv) | |
2280 | ||
5fb8527f | 2281 | =item SvNOK_only |
2282 | ||
2283 | Tells an SV that it is a double and disables all other OK bits. | |
2284 | ||
2285 | SvNOK_on (SV* sv) | |
2286 | ||
2287 | =item SvNOK_only | |
2288 | ||
2289 | Tells an SV that it is a double and disables all other OK bits. | |
2290 | ||
2291 | SvNOK_on (SV* sv) | |
2292 | ||
cb1a09d0 AD |
2293 | =item SvNOKp |
2294 | ||
2295 | Returns a boolean indicating whether the SV contains a double. Checks the | |
2296 | B<private> setting. Use C<SvNOK>. | |
2297 | ||
2298 | int SvNOKp (SV* SV) | |
2299 | ||
2300 | =item SvNV | |
2301 | ||
2302 | Returns the double which is stored in the SV. | |
2303 | ||
2304 | double SvNV (SV* sv); | |
2305 | ||
2306 | =item SvNVX | |
2307 | ||
2308 | Returns the double which is stored in the SV. | |
2309 | ||
2310 | double SvNVX (SV* sv); | |
2311 | ||
2312 | =item SvPOK | |
2313 | ||
2314 | Returns a boolean indicating whether the SV contains a character string. | |
2315 | ||
2316 | int SvPOK (SV* SV) | |
2317 | ||
2318 | =item SvPOK_off | |
2319 | ||
2320 | Unsets the PV status of an SV. | |
2321 | ||
2322 | SvPOK_off (SV* sv) | |
2323 | ||
2324 | =item SvPOK_on | |
2325 | ||
2326 | Tells an SV that it is a string. | |
2327 | ||
2328 | SvPOK_on (SV* sv) | |
2329 | ||
5fb8527f | 2330 | =item SvPOK_only |
2331 | ||
2332 | Tells an SV that it is a string and disables all other OK bits. | |
2333 | ||
2334 | SvPOK_on (SV* sv) | |
2335 | ||
2336 | =item SvPOK_only | |
2337 | ||
2338 | Tells an SV that it is a string and disables all other OK bits. | |
2339 | ||
2340 | SvPOK_on (SV* sv) | |
2341 | ||
cb1a09d0 AD |
2342 | =item SvPOKp |
2343 | ||
2344 | Returns a boolean indicating whether the SV contains a character string. | |
2345 | Checks the B<private> setting. Use C<SvPOK>. | |
2346 | ||
2347 | int SvPOKp (SV* SV) | |
2348 | ||
2349 | =item SvPV | |
2350 | ||
2351 | Returns a pointer to the string in the SV, or a stringified form of the SV | |
2352 | if the SV does not contain a string. If C<len> is C<na> then Perl will | |
2353 | handle the length on its own. | |
2354 | ||
2355 | char * SvPV (SV* sv, int len ) | |
2356 | ||
2357 | =item SvPVX | |
2358 | ||
2359 | Returns a pointer to the string in the SV. The SV must contain a string. | |
2360 | ||
2361 | char * SvPVX (SV* sv) | |
2362 | ||
2363 | =item SvREFCNT | |
2364 | ||
5f05dabc | 2365 | Returns the value of the object's reference count. |
cb1a09d0 AD |
2366 | |
2367 | int SvREFCNT (SV* sv); | |
2368 | ||
2369 | =item SvREFCNT_dec | |
2370 | ||
5f05dabc | 2371 | Decrements the reference count of the given SV. |
cb1a09d0 AD |
2372 | |
2373 | void SvREFCNT_dec (SV* sv) | |
2374 | ||
2375 | =item SvREFCNT_inc | |
2376 | ||
5f05dabc | 2377 | Increments the reference count of the given SV. |
cb1a09d0 AD |
2378 | |
2379 | void SvREFCNT_inc (SV* sv) | |
2380 | ||
2381 | =item SvROK | |
2382 | ||
2383 | Tests if the SV is an RV. | |
2384 | ||
2385 | int SvROK (SV* sv) | |
2386 | ||
2387 | =item SvROK_off | |
2388 | ||
2389 | Unsets the RV status of an SV. | |
2390 | ||
2391 | SvROK_off (SV* sv) | |
2392 | ||
2393 | =item SvROK_on | |
2394 | ||
2395 | Tells an SV that it is an RV. | |
2396 | ||
2397 | SvROK_on (SV* sv) | |
2398 | ||
2399 | =item SvRV | |
2400 | ||
2401 | Dereferences an RV to return the SV. | |
2402 | ||
2403 | SV* SvRV (SV* sv); | |
2404 | ||
2405 | =item sv_setiv | |
2406 | ||
2407 | Copies an integer into the given SV. | |
2408 | ||
2409 | void sv_setiv _((SV* sv, IV num)); | |
2410 | ||
2411 | =item sv_setnv | |
2412 | ||
2413 | Copies a double into the given SV. | |
2414 | ||
2415 | void sv_setnv _((SV* sv, double num)); | |
2416 | ||
2417 | =item sv_setpv | |
2418 | ||
2419 | Copies a string into an SV. The string must be null-terminated. | |
2420 | ||
2421 | void sv_setpv _((SV* sv, char* ptr)); | |
2422 | ||
2423 | =item sv_setpvn | |
2424 | ||
2425 | Copies a string into an SV. The C<len> parameter indicates the number of | |
2426 | bytes to be copied. | |
2427 | ||
2428 | void sv_setpvn _((SV* sv, char* ptr, STRLEN len)); | |
2429 | ||
2430 | =item sv_setref_iv | |
2431 | ||
5fb8527f | 2432 | Copies an integer into a new SV, optionally blessing the SV. The C<rv> |
2433 | argument will be upgraded to an RV. That RV will be modified to point to | |
2434 | the new SV. The C<classname> argument indicates the package for the | |
2435 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV | |
5f05dabc | 2436 | will be returned and will have a reference count of 1. |
cb1a09d0 AD |
2437 | |
2438 | SV* sv_setref_iv _((SV *rv, char *classname, IV iv)); | |
2439 | ||
2440 | =item sv_setref_nv | |
2441 | ||
5fb8527f | 2442 | Copies a double into a new SV, optionally blessing the SV. The C<rv> |
2443 | argument will be upgraded to an RV. That RV will be modified to point to | |
2444 | the new SV. The C<classname> argument indicates the package for the | |
2445 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV | |
5f05dabc | 2446 | will be returned and will have a reference count of 1. |
cb1a09d0 AD |
2447 | |
2448 | SV* sv_setref_nv _((SV *rv, char *classname, double nv)); | |
2449 | ||
2450 | =item sv_setref_pv | |
2451 | ||
5fb8527f | 2452 | Copies a pointer into a new SV, optionally blessing the SV. The C<rv> |
2453 | argument will be upgraded to an RV. That RV will be modified to point to | |
2454 | the new SV. If the C<pv> argument is NULL then C<sv_undef> will be placed | |
2455 | into the SV. The C<classname> argument indicates the package for the | |
2456 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV | |
5f05dabc | 2457 | will be returned and will have a reference count of 1. |
cb1a09d0 AD |
2458 | |
2459 | SV* sv_setref_pv _((SV *rv, char *classname, void* pv)); | |
2460 | ||
2461 | Do not use with integral Perl types such as HV, AV, SV, CV, because those | |
2462 | objects will become corrupted by the pointer copy process. | |
2463 | ||
2464 | Note that C<sv_setref_pvn> copies the string while this copies the pointer. | |
2465 | ||
2466 | =item sv_setref_pvn | |
2467 | ||
5fb8527f | 2468 | Copies a string into a new SV, optionally blessing the SV. The length of the |
2469 | string must be specified with C<n>. The C<rv> argument will be upgraded to | |
2470 | an RV. That RV will be modified to point to the new SV. The C<classname> | |
cb1a09d0 AD |
2471 | argument indicates the package for the blessing. Set C<classname> to |
2472 | C<Nullch> to avoid the blessing. The new SV will be returned and will have | |
5f05dabc | 2473 | a reference count of 1. |
cb1a09d0 AD |
2474 | |
2475 | SV* sv_setref_pvn _((SV *rv, char *classname, char* pv, I32 n)); | |
2476 | ||
2477 | Note that C<sv_setref_pv> copies the pointer while this copies the string. | |
2478 | ||
2479 | =item sv_setsv | |
2480 | ||
2481 | Copies the contents of the source SV C<ssv> into the destination SV C<dsv>. | |
5f05dabc | 2482 | The source SV may be destroyed if it is mortal. |
cb1a09d0 AD |
2483 | |
2484 | void sv_setsv _((SV* dsv, SV* ssv)); | |
2485 | ||
2486 | =item SvSTASH | |
2487 | ||
2488 | Returns the stash of the SV. | |
2489 | ||
2490 | HV * SvSTASH (SV* sv) | |
2491 | ||
2492 | =item SVt_IV | |
2493 | ||
2494 | Integer type flag for scalars. See C<svtype>. | |
2495 | ||
2496 | =item SVt_PV | |
2497 | ||
2498 | Pointer type flag for scalars. See C<svtype>. | |
2499 | ||
2500 | =item SVt_PVAV | |
2501 | ||
2502 | Type flag for arrays. See C<svtype>. | |
2503 | ||
2504 | =item SVt_PVCV | |
2505 | ||
2506 | Type flag for code refs. See C<svtype>. | |
2507 | ||
2508 | =item SVt_PVHV | |
2509 | ||
2510 | Type flag for hashes. See C<svtype>. | |
2511 | ||
2512 | =item SVt_PVMG | |
2513 | ||
2514 | Type flag for blessed scalars. See C<svtype>. | |
2515 | ||
2516 | =item SVt_NV | |
2517 | ||
2518 | Double type flag for scalars. See C<svtype>. | |
2519 | ||
2520 | =item SvTRUE | |
2521 | ||
2522 | Returns a boolean indicating whether Perl would evaluate the SV as true or | |
2523 | false, defined or undefined. | |
2524 | ||
2525 | int SvTRUE (SV* sv) | |
2526 | ||
2527 | =item SvTYPE | |
2528 | ||
2529 | Returns the type of the SV. See C<svtype>. | |
2530 | ||
2531 | svtype SvTYPE (SV* sv) | |
2532 | ||
2533 | =item svtype | |
2534 | ||
2535 | An enum of flags for Perl types. These are found in the file B<sv.h> in the | |
2536 | C<svtype> enum. Test these flags with the C<SvTYPE> macro. | |
2537 | ||
2538 | =item SvUPGRADE | |
2539 | ||
5fb8527f | 2540 | Used to upgrade an SV to a more complex form. Uses C<sv_upgrade> to perform |
2541 | the upgrade if necessary. See C<svtype>. | |
2542 | ||
2543 | bool SvUPGRADE _((SV* sv, svtype mt)); | |
2544 | ||
2545 | =item sv_upgrade | |
2546 | ||
2547 | Upgrade an SV to a more complex form. Use C<SvUPGRADE>. See C<svtype>. | |
cb1a09d0 AD |
2548 | |
2549 | =item sv_undef | |
2550 | ||
2551 | This is the C<undef> SV. Always refer to this as C<&sv_undef>. | |
2552 | ||
5fb8527f | 2553 | =item sv_unref |
2554 | ||
07fa94a1 JO |
2555 | Unsets the RV status of the SV, and decrements the reference count of |
2556 | whatever was being referenced by the RV. This can almost be thought of | |
2557 | as a reversal of C<newSVrv>. See C<SvROK_off>. | |
5fb8527f | 2558 | |
2559 | void sv_unref _((SV* sv)); | |
2560 | ||
cb1a09d0 AD |
2561 | =item sv_usepvn |
2562 | ||
2563 | Tells an SV to use C<ptr> to find its string value. Normally the string is | |
5fb8527f | 2564 | stored inside the SV but sv_usepvn allows the SV to use an outside string. |
2565 | The C<ptr> should point to memory that was allocated by C<malloc>. The | |
cb1a09d0 AD |
2566 | string length, C<len>, must be supplied. This function will realloc the |
2567 | memory pointed to by C<ptr>, so that pointer should not be freed or used by | |
2568 | the programmer after giving it to sv_usepvn. | |
2569 | ||
2570 | void sv_usepvn _((SV* sv, char* ptr, STRLEN len)); | |
2571 | ||
2572 | =item sv_yes | |
2573 | ||
2574 | This is the C<true> SV. See C<sv_no>. Always refer to this as C<&sv_yes>. | |
2575 | ||
2576 | =item THIS | |
2577 | ||
2578 | Variable which is setup by C<xsubpp> to designate the object in a C++ XSUB. | |
2579 | This is always the proper type for the C++ object. See C<CLASS> and | |
5fb8527f | 2580 | L<perlxs/"Using XS With C++">. |
cb1a09d0 AD |
2581 | |
2582 | =item toLOWER | |
2583 | ||
2584 | Converts the specified character to lowercase. | |
2585 | ||
2586 | int toLOWER (char c) | |
2587 | ||
2588 | =item toUPPER | |
2589 | ||
2590 | Converts the specified character to uppercase. | |
2591 | ||
2592 | int toUPPER (char c) | |
2593 | ||
2594 | =item warn | |
2595 | ||
2596 | This is the XSUB-writer's interface to Perl's C<warn> function. Use this | |
2597 | function the same way you use the C C<printf> function. See C<croak()>. | |
2598 | ||
2599 | =item XPUSHi | |
2600 | ||
2601 | Push an integer onto the stack, extending the stack if necessary. See | |
2602 | C<PUSHi>. | |
2603 | ||
2604 | XPUSHi(int d) | |
2605 | ||
2606 | =item XPUSHn | |
2607 | ||
2608 | Push a double onto the stack, extending the stack if necessary. See | |
2609 | C<PUSHn>. | |
2610 | ||
2611 | XPUSHn(double d) | |
2612 | ||
2613 | =item XPUSHp | |
2614 | ||
2615 | Push a string onto the stack, extending the stack if necessary. The C<len> | |
2616 | indicates the length of the string. See C<PUSHp>. | |
2617 | ||
2618 | XPUSHp(char *c, int len) | |
2619 | ||
2620 | =item XPUSHs | |
2621 | ||
2622 | Push an SV onto the stack, extending the stack if necessary. See C<PUSHs>. | |
2623 | ||
2624 | XPUSHs(sv) | |
2625 | ||
5fb8527f | 2626 | =item XS |
2627 | ||
2628 | Macro to declare an XSUB and its C parameter list. This is handled by | |
2629 | C<xsubpp>. | |
2630 | ||
cb1a09d0 AD |
2631 | =item XSRETURN |
2632 | ||
2633 | Return from XSUB, indicating number of items on the stack. This is usually | |
2634 | handled by C<xsubpp>. | |
2635 | ||
5fb8527f | 2636 | XSRETURN(int x); |
cb1a09d0 AD |
2637 | |
2638 | =item XSRETURN_EMPTY | |
2639 | ||
5fb8527f | 2640 | Return an empty list from an XSUB immediately. |
cb1a09d0 AD |
2641 | |
2642 | XSRETURN_EMPTY; | |
2643 | ||
5fb8527f | 2644 | =item XSRETURN_IV |
2645 | ||
2646 | Return an integer from an XSUB immediately. Uses C<XST_mIV>. | |
2647 | ||
2648 | XSRETURN_IV(IV v); | |
2649 | ||
cb1a09d0 AD |
2650 | =item XSRETURN_NO |
2651 | ||
5fb8527f | 2652 | Return C<&sv_no> from an XSUB immediately. Uses C<XST_mNO>. |
cb1a09d0 AD |
2653 | |
2654 | XSRETURN_NO; | |
2655 | ||
5fb8527f | 2656 | =item XSRETURN_NV |
2657 | ||
2658 | Return an double from an XSUB immediately. Uses C<XST_mNV>. | |
2659 | ||
2660 | XSRETURN_NV(NV v); | |
2661 | ||
2662 | =item XSRETURN_PV | |
2663 | ||
2664 | Return a copy of a string from an XSUB immediately. Uses C<XST_mPV>. | |
2665 | ||
2666 | XSRETURN_PV(char *v); | |
2667 | ||
cb1a09d0 AD |
2668 | =item XSRETURN_UNDEF |
2669 | ||
5fb8527f | 2670 | Return C<&sv_undef> from an XSUB immediately. Uses C<XST_mUNDEF>. |
cb1a09d0 AD |
2671 | |
2672 | XSRETURN_UNDEF; | |
2673 | ||
2674 | =item XSRETURN_YES | |
2675 | ||
5fb8527f | 2676 | Return C<&sv_yes> from an XSUB immediately. Uses C<XST_mYES>. |
cb1a09d0 AD |
2677 | |
2678 | XSRETURN_YES; | |
2679 | ||
5fb8527f | 2680 | =item XST_mIV |
2681 | ||
2682 | Place an integer into the specified position C<i> on the stack. The value is | |
2683 | stored in a new mortal SV. | |
2684 | ||
2685 | XST_mIV( int i, IV v ); | |
2686 | ||
2687 | =item XST_mNV | |
2688 | ||
2689 | Place a double into the specified position C<i> on the stack. The value is | |
2690 | stored in a new mortal SV. | |
2691 | ||
2692 | XST_mNV( int i, NV v ); | |
2693 | ||
2694 | =item XST_mNO | |
2695 | ||
2696 | Place C<&sv_no> into the specified position C<i> on the stack. | |
2697 | ||
2698 | XST_mNO( int i ); | |
2699 | ||
2700 | =item XST_mPV | |
2701 | ||
2702 | Place a copy of a string into the specified position C<i> on the stack. The | |
2703 | value is stored in a new mortal SV. | |
2704 | ||
2705 | XST_mPV( int i, char *v ); | |
2706 | ||
2707 | =item XST_mUNDEF | |
2708 | ||
2709 | Place C<&sv_undef> into the specified position C<i> on the stack. | |
2710 | ||
2711 | XST_mUNDEF( int i ); | |
2712 | ||
2713 | =item XST_mYES | |
2714 | ||
2715 | Place C<&sv_yes> into the specified position C<i> on the stack. | |
2716 | ||
2717 | XST_mYES( int i ); | |
2718 | ||
2719 | =item XS_VERSION | |
2720 | ||
2721 | The version identifier for an XS module. This is usually handled | |
2722 | automatically by C<ExtUtils::MakeMaker>. See C<XS_VERSION_BOOTCHECK>. | |
2723 | ||
2724 | =item XS_VERSION_BOOTCHECK | |
2725 | ||
2726 | Macro to verify that a PM module's $VERSION variable matches the XS module's | |
2727 | C<XS_VERSION> variable. This is usually handled automatically by | |
2728 | C<xsubpp>. See L<perlxs/"The VERSIONCHECK: Keyword">. | |
2729 | ||
cb1a09d0 AD |
2730 | =item Zero |
2731 | ||
2732 | The XSUB-writer's interface to the C C<memzero> function. The C<d> is the | |
2733 | destination, C<n> is the number of items, and C<t> is the type. | |
2734 | ||
2735 | (void) Zero( d, n, t ); | |
2736 | ||
2737 | =back | |
2738 | ||
5f05dabc | 2739 | =head1 EDITOR |
cb1a09d0 | 2740 | |
55497cff | 2741 | Jeff Okamoto <okamoto@corp.hp.com> |
cb1a09d0 AD |
2742 | |
2743 | With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, | |
2744 | Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil | |
55497cff | 2745 | Bowers, Matthew Green, Tim Bunce, Spider Boardman, and Ulrich Pfeifer. |
cb1a09d0 | 2746 | |
55497cff | 2747 | API Listing by Dean Roehrich <roehrich@cray.com>. |
cb1a09d0 AD |
2748 | |
2749 | =head1 DATE | |
2750 | ||
0a753a76 | 2751 | Version 31: 1997/1/27 |