| 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 | |
| 11 | =head1 Variables |
| 12 | |
| 13 | =head2 Datatypes |
| 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 | |
| 21 | Each typedef has specific routines that manipulate the various data types. |
| 22 | |
| 23 | =head2 What is an "IV"? |
| 24 | |
| 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). |
| 27 | |
| 28 | Perl also uses two special typedefs, I32 and I16, which will always be at |
| 29 | least 32-bits and 16-bits long, respectively. |
| 30 | |
| 31 | =head2 Working with SVs |
| 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 six routines are: |
| 38 | |
| 39 | SV* newSViv(IV); |
| 40 | SV* newSVnv(double); |
| 41 | SV* newSVpv(char*, int); |
| 42 | SV* newSVpvn(char*, int); |
| 43 | SV* newSVpvf(const char*, ...); |
| 44 | SV* newSVsv(SV*); |
| 45 | |
| 46 | To change the value of an *already-existing* SV, there are seven routines: |
| 47 | |
| 48 | void sv_setiv(SV*, IV); |
| 49 | void sv_setuv(SV*, UV); |
| 50 | void sv_setnv(SV*, double); |
| 51 | void sv_setpv(SV*, char*); |
| 52 | void sv_setpvn(SV*, char*, int) |
| 53 | void sv_setpvf(SV*, const char*, ...); |
| 54 | void sv_setsv(SV*, SV*); |
| 55 | |
| 56 | Notice that you can choose to specify the length of the string to be |
| 57 | assigned by using C<sv_setpvn>, C<newSVpvn>, or C<newSVpv>, or you may |
| 58 | allow Perl to calculate the length by using C<sv_setpv> or by specifying |
| 59 | 0 as the second argument to C<newSVpv>. Be warned, though, that Perl will |
| 60 | determine the string's length by using C<strlen>, which depends on the |
| 61 | string terminating with a NUL character. The arguments of C<sv_setpvf> |
| 62 | are processed like C<sprintf>, and the formatted output becomes the value. |
| 63 | The C<sv_set*()> functions are not generic enough to operate on values |
| 64 | that have "magic". See L<Magic Virtual Tables> later in this document. |
| 65 | |
| 66 | All SVs that will contain strings should, but need not, be terminated |
| 67 | with a NUL character. If it is not NUL-terminated there is a risk of |
| 68 | core dumps and corruptions from code which passes the string to C |
| 69 | functions or system calls which expect a NUL-terminated string. |
| 70 | Perl's own functions typically add a trailing NUL for this reason. |
| 71 | Nevertheless, you should be very careful when you pass a string stored |
| 72 | in an SV to a C function or system call. |
| 73 | |
| 74 | To access the actual value that an SV points to, you can use the macros: |
| 75 | |
| 76 | SvIV(SV*) |
| 77 | SvNV(SV*) |
| 78 | SvPV(SV*, STRLEN len) |
| 79 | |
| 80 | which will automatically coerce the actual scalar type into an IV, double, |
| 81 | or string. |
| 82 | |
| 83 | In the C<SvPV> macro, the length of the string returned is placed into the |
| 84 | variable C<len> (this is a macro, so you do I<not> use C<&len>). If you do not |
| 85 | care what the length of the data is, use the global variable C<na>. Remember, |
| 86 | however, that Perl allows arbitrary strings of data that may both contain |
| 87 | NULs and might not be terminated by a NUL. |
| 88 | |
| 89 | If you want to know if the scalar value is TRUE, you can use: |
| 90 | |
| 91 | SvTRUE(SV*) |
| 92 | |
| 93 | Although Perl will automatically grow strings for you, if you need to force |
| 94 | Perl to allocate more memory for your SV, you can use the macro |
| 95 | |
| 96 | SvGROW(SV*, STRLEN newlen) |
| 97 | |
| 98 | which will determine if more memory needs to be allocated. If so, it will |
| 99 | call the function C<sv_grow>. Note that C<SvGROW> can only increase, not |
| 100 | decrease, the allocated memory of an SV and that it does not automatically |
| 101 | add a byte for the a trailing NUL (perl's own string functions typically do |
| 102 | C<SvGROW(sv, len + 1)>). |
| 103 | |
| 104 | If you have an SV and want to know what kind of data Perl thinks is stored |
| 105 | in it, you can use the following macros to check the type of SV you have. |
| 106 | |
| 107 | SvIOK(SV*) |
| 108 | SvNOK(SV*) |
| 109 | SvPOK(SV*) |
| 110 | |
| 111 | You can get and set the current length of the string stored in an SV with |
| 112 | the following macros: |
| 113 | |
| 114 | SvCUR(SV*) |
| 115 | SvCUR_set(SV*, I32 val) |
| 116 | |
| 117 | You can also get a pointer to the end of the string stored in the SV |
| 118 | with the macro: |
| 119 | |
| 120 | SvEND(SV*) |
| 121 | |
| 122 | But note that these last three macros are valid only if C<SvPOK()> is true. |
| 123 | |
| 124 | If you want to append something to the end of string stored in an C<SV*>, |
| 125 | you can use the following functions: |
| 126 | |
| 127 | void sv_catpv(SV*, char*); |
| 128 | void sv_catpvn(SV*, char*, int); |
| 129 | void sv_catpvf(SV*, const char*, ...); |
| 130 | void sv_catsv(SV*, SV*); |
| 131 | |
| 132 | The first function calculates the length of the string to be appended by |
| 133 | using C<strlen>. In the second, you specify the length of the string |
| 134 | yourself. The third function processes its arguments like C<sprintf> and |
| 135 | appends the formatted output. The fourth function extends the string |
| 136 | stored in the first SV with the string stored in the second SV. It also |
| 137 | forces the second SV to be interpreted as a string. The C<sv_cat*()> |
| 138 | functions are not generic enough to operate on values that have "magic". |
| 139 | See L<Magic Virtual Tables> later in this document. |
| 140 | |
| 141 | If you know the name of a scalar variable, you can get a pointer to its SV |
| 142 | by using the following: |
| 143 | |
| 144 | SV* perl_get_sv("package::varname", FALSE); |
| 145 | |
| 146 | This returns NULL if the variable does not exist. |
| 147 | |
| 148 | If you want to know if this variable (or any other SV) is actually C<defined>, |
| 149 | you can call: |
| 150 | |
| 151 | SvOK(SV*) |
| 152 | |
| 153 | The scalar C<undef> value is stored in an SV instance called C<sv_undef>. Its |
| 154 | address can be used whenever an C<SV*> is needed. |
| 155 | |
| 156 | There are also the two values C<sv_yes> and C<sv_no>, which contain Boolean |
| 157 | TRUE and FALSE values, respectively. Like C<sv_undef>, their addresses can |
| 158 | be used whenever an C<SV*> is needed. |
| 159 | |
| 160 | Do not be fooled into thinking that C<(SV *) 0> is the same as C<&sv_undef>. |
| 161 | Take this code: |
| 162 | |
| 163 | SV* sv = (SV*) 0; |
| 164 | if (I-am-to-return-a-real-value) { |
| 165 | sv = sv_2mortal(newSViv(42)); |
| 166 | } |
| 167 | sv_setsv(ST(0), sv); |
| 168 | |
| 169 | This code tries to return a new SV (which contains the value 42) if it should |
| 170 | return a real value, or undef otherwise. Instead it has returned a NULL |
| 171 | pointer which, somewhere down the line, will cause a segmentation violation, |
| 172 | bus error, or just weird results. Change the zero to C<&sv_undef> in the first |
| 173 | line and all will be well. |
| 174 | |
| 175 | To free an SV that you've created, call C<SvREFCNT_dec(SV*)>. Normally this |
| 176 | call is not necessary (see L<Reference Counts and Mortality>). |
| 177 | |
| 178 | =head2 What's Really Stored in an SV? |
| 179 | |
| 180 | Recall that the usual method of determining the type of scalar you have is |
| 181 | to use C<Sv*OK> macros. Because a scalar can be both a number and a string, |
| 182 | usually these macros will always return TRUE and calling the C<Sv*V> |
| 183 | macros will do the appropriate conversion of string to integer/double or |
| 184 | integer/double to string. |
| 185 | |
| 186 | If you I<really> need to know if you have an integer, double, or string |
| 187 | pointer in an SV, you can use the following three macros instead: |
| 188 | |
| 189 | SvIOKp(SV*) |
| 190 | SvNOKp(SV*) |
| 191 | SvPOKp(SV*) |
| 192 | |
| 193 | These will tell you if you truly have an integer, double, or string pointer |
| 194 | stored in your SV. The "p" stands for private. |
| 195 | |
| 196 | In general, though, it's best to use the C<Sv*V> macros. |
| 197 | |
| 198 | =head2 Working with AVs |
| 199 | |
| 200 | There are two ways to create and load an AV. The first method creates an |
| 201 | empty AV: |
| 202 | |
| 203 | AV* newAV(); |
| 204 | |
| 205 | The second method both creates the AV and initially populates it with SVs: |
| 206 | |
| 207 | AV* av_make(I32 num, SV **ptr); |
| 208 | |
| 209 | The second argument points to an array containing C<num> C<SV*>'s. Once the |
| 210 | AV has been created, the SVs can be destroyed, if so desired. |
| 211 | |
| 212 | Once the AV has been created, the following operations are possible on AVs: |
| 213 | |
| 214 | void av_push(AV*, SV*); |
| 215 | SV* av_pop(AV*); |
| 216 | SV* av_shift(AV*); |
| 217 | void av_unshift(AV*, I32 num); |
| 218 | |
| 219 | These should be familiar operations, with the exception of C<av_unshift>. |
| 220 | This routine adds C<num> elements at the front of the array with the C<undef> |
| 221 | value. You must then use C<av_store> (described below) to assign values |
| 222 | to these new elements. |
| 223 | |
| 224 | Here are some other functions: |
| 225 | |
| 226 | I32 av_len(AV*); |
| 227 | SV** av_fetch(AV*, I32 key, I32 lval); |
| 228 | SV** av_store(AV*, I32 key, SV* val); |
| 229 | |
| 230 | The C<av_len> function returns the highest index value in array (just |
| 231 | like $#array in Perl). If the array is empty, -1 is returned. The |
| 232 | C<av_fetch> function returns the value at index C<key>, but if C<lval> |
| 233 | is non-zero, then C<av_fetch> will store an undef value at that index. |
| 234 | The C<av_store> function stores the value C<val> at index C<key>, and does |
| 235 | not increment the reference count of C<val>. Thus the caller is responsible |
| 236 | for taking care of that, and if C<av_store> returns NULL, the caller will |
| 237 | have to decrement the reference count to avoid a memory leak. Note that |
| 238 | C<av_fetch> and C<av_store> both return C<SV**>'s, not C<SV*>'s as their |
| 239 | return value. |
| 240 | |
| 241 | void av_clear(AV*); |
| 242 | void av_undef(AV*); |
| 243 | void av_extend(AV*, I32 key); |
| 244 | |
| 245 | The C<av_clear> function deletes all the elements in the AV* array, but |
| 246 | does not actually delete the array itself. The C<av_undef> function will |
| 247 | delete all the elements in the array plus the array itself. The |
| 248 | C<av_extend> function extends the array so that it contains C<key> |
| 249 | elements. If C<key> is less than the current length of the array, then |
| 250 | nothing is done. |
| 251 | |
| 252 | If you know the name of an array variable, you can get a pointer to its AV |
| 253 | by using the following: |
| 254 | |
| 255 | AV* perl_get_av("package::varname", FALSE); |
| 256 | |
| 257 | This returns NULL if the variable does not exist. |
| 258 | |
| 259 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 260 | information on how to use the array access functions on tied arrays. |
| 261 | |
| 262 | =head2 Working with HVs |
| 263 | |
| 264 | To create an HV, you use the following routine: |
| 265 | |
| 266 | HV* newHV(); |
| 267 | |
| 268 | Once the HV has been created, the following operations are possible on HVs: |
| 269 | |
| 270 | SV** hv_store(HV*, char* key, U32 klen, SV* val, U32 hash); |
| 271 | SV** hv_fetch(HV*, char* key, U32 klen, I32 lval); |
| 272 | |
| 273 | The C<klen> parameter is the length of the key being passed in (Note that |
| 274 | you cannot pass 0 in as a value of C<klen> to tell Perl to measure the |
| 275 | length of the key). The C<val> argument contains the SV pointer to the |
| 276 | scalar being stored, and C<hash> is the precomputed hash value (zero if |
| 277 | you want C<hv_store> to calculate it for you). The C<lval> parameter |
| 278 | indicates whether this fetch is actually a part of a store operation, in |
| 279 | which case a new undefined value will be added to the HV with the supplied |
| 280 | key and C<hv_fetch> will return as if the value had already existed. |
| 281 | |
| 282 | Remember that C<hv_store> and C<hv_fetch> return C<SV**>'s and not just |
| 283 | C<SV*>. To access the scalar value, you must first dereference the return |
| 284 | value. However, you should check to make sure that the return value is |
| 285 | not NULL before dereferencing it. |
| 286 | |
| 287 | These two functions check if a hash table entry exists, and deletes it. |
| 288 | |
| 289 | bool hv_exists(HV*, char* key, U32 klen); |
| 290 | SV* hv_delete(HV*, char* key, U32 klen, I32 flags); |
| 291 | |
| 292 | If C<flags> does not include the C<G_DISCARD> flag then C<hv_delete> will |
| 293 | create and return a mortal copy of the deleted value. |
| 294 | |
| 295 | And more miscellaneous functions: |
| 296 | |
| 297 | void hv_clear(HV*); |
| 298 | void hv_undef(HV*); |
| 299 | |
| 300 | Like their AV counterparts, C<hv_clear> deletes all the entries in the hash |
| 301 | table but does not actually delete the hash table. The C<hv_undef> deletes |
| 302 | both the entries and the hash table itself. |
| 303 | |
| 304 | Perl keeps the actual data in linked list of structures with a typedef of HE. |
| 305 | These contain the actual key and value pointers (plus extra administrative |
| 306 | overhead). The key is a string pointer; the value is an C<SV*>. However, |
| 307 | once you have an C<HE*>, to get the actual key and value, use the routines |
| 308 | specified below. |
| 309 | |
| 310 | I32 hv_iterinit(HV*); |
| 311 | /* Prepares starting point to traverse hash table */ |
| 312 | HE* hv_iternext(HV*); |
| 313 | /* Get the next entry, and return a pointer to a |
| 314 | structure that has both the key and value */ |
| 315 | char* hv_iterkey(HE* entry, I32* retlen); |
| 316 | /* Get the key from an HE structure and also return |
| 317 | the length of the key string */ |
| 318 | SV* hv_iterval(HV*, HE* entry); |
| 319 | /* Return a SV pointer to the value of the HE |
| 320 | structure */ |
| 321 | SV* hv_iternextsv(HV*, char** key, I32* retlen); |
| 322 | /* This convenience routine combines hv_iternext, |
| 323 | hv_iterkey, and hv_iterval. The key and retlen |
| 324 | arguments are return values for the key and its |
| 325 | length. The value is returned in the SV* argument */ |
| 326 | |
| 327 | If you know the name of a hash variable, you can get a pointer to its HV |
| 328 | by using the following: |
| 329 | |
| 330 | HV* perl_get_hv("package::varname", FALSE); |
| 331 | |
| 332 | This returns NULL if the variable does not exist. |
| 333 | |
| 334 | The hash algorithm is defined in the C<PERL_HASH(hash, key, klen)> macro: |
| 335 | |
| 336 | i = klen; |
| 337 | hash = 0; |
| 338 | s = key; |
| 339 | while (i--) |
| 340 | hash = hash * 33 + *s++; |
| 341 | |
| 342 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 343 | information on how to use the hash access functions on tied hashes. |
| 344 | |
| 345 | =head2 Hash API Extensions |
| 346 | |
| 347 | Beginning with version 5.004, the following functions are also supported: |
| 348 | |
| 349 | HE* hv_fetch_ent (HV* tb, SV* key, I32 lval, U32 hash); |
| 350 | HE* hv_store_ent (HV* tb, SV* key, SV* val, U32 hash); |
| 351 | |
| 352 | bool hv_exists_ent (HV* tb, SV* key, U32 hash); |
| 353 | SV* hv_delete_ent (HV* tb, SV* key, I32 flags, U32 hash); |
| 354 | |
| 355 | SV* hv_iterkeysv (HE* entry); |
| 356 | |
| 357 | Note that these functions take C<SV*> keys, which simplifies writing |
| 358 | of extension code that deals with hash structures. These functions |
| 359 | also allow passing of C<SV*> keys to C<tie> functions without forcing |
| 360 | you to stringify the keys (unlike the previous set of functions). |
| 361 | |
| 362 | They also return and accept whole hash entries (C<HE*>), making their |
| 363 | use more efficient (since the hash number for a particular string |
| 364 | doesn't have to be recomputed every time). See L<API LISTING> later in |
| 365 | this document for detailed descriptions. |
| 366 | |
| 367 | The following macros must always be used to access the contents of hash |
| 368 | entries. Note that the arguments to these macros must be simple |
| 369 | variables, since they may get evaluated more than once. See |
| 370 | L<API LISTING> later in this document for detailed descriptions of these |
| 371 | macros. |
| 372 | |
| 373 | HePV(HE* he, STRLEN len) |
| 374 | HeVAL(HE* he) |
| 375 | HeHASH(HE* he) |
| 376 | HeSVKEY(HE* he) |
| 377 | HeSVKEY_force(HE* he) |
| 378 | HeSVKEY_set(HE* he, SV* sv) |
| 379 | |
| 380 | These two lower level macros are defined, but must only be used when |
| 381 | dealing with keys that are not C<SV*>s: |
| 382 | |
| 383 | HeKEY(HE* he) |
| 384 | HeKLEN(HE* he) |
| 385 | |
| 386 | Note that both C<hv_store> and C<hv_store_ent> do not increment the |
| 387 | reference count of the stored C<val>, which is the caller's responsibility. |
| 388 | If these functions return a NULL value, the caller will usually have to |
| 389 | decrement the reference count of C<val> to avoid a memory leak. |
| 390 | |
| 391 | =head2 References |
| 392 | |
| 393 | References are a special type of scalar that point to other data types |
| 394 | (including references). |
| 395 | |
| 396 | To create a reference, use either of the following functions: |
| 397 | |
| 398 | SV* newRV_inc((SV*) thing); |
| 399 | SV* newRV_noinc((SV*) thing); |
| 400 | |
| 401 | The C<thing> argument can be any of an C<SV*>, C<AV*>, or C<HV*>. The |
| 402 | functions are identical except that C<newRV_inc> increments the reference |
| 403 | count of the C<thing>, while C<newRV_noinc> does not. For historical |
| 404 | reasons, C<newRV> is a synonym for C<newRV_inc>. |
| 405 | |
| 406 | Once you have a reference, you can use the following macro to dereference |
| 407 | the reference: |
| 408 | |
| 409 | SvRV(SV*) |
| 410 | |
| 411 | then call the appropriate routines, casting the returned C<SV*> to either an |
| 412 | C<AV*> or C<HV*>, if required. |
| 413 | |
| 414 | To determine if an SV is a reference, you can use the following macro: |
| 415 | |
| 416 | SvROK(SV*) |
| 417 | |
| 418 | To discover what type of value the reference refers to, use the following |
| 419 | macro and then check the return value. |
| 420 | |
| 421 | SvTYPE(SvRV(SV*)) |
| 422 | |
| 423 | The most useful types that will be returned are: |
| 424 | |
| 425 | SVt_IV Scalar |
| 426 | SVt_NV Scalar |
| 427 | SVt_PV Scalar |
| 428 | SVt_RV Scalar |
| 429 | SVt_PVAV Array |
| 430 | SVt_PVHV Hash |
| 431 | SVt_PVCV Code |
| 432 | SVt_PVGV Glob (possible a file handle) |
| 433 | SVt_PVMG Blessed or Magical Scalar |
| 434 | |
| 435 | See the sv.h header file for more details. |
| 436 | |
| 437 | =head2 Blessed References and Class Objects |
| 438 | |
| 439 | References are also used to support object-oriented programming. In the |
| 440 | OO lexicon, an object is simply a reference that has been blessed into a |
| 441 | package (or class). Once blessed, the programmer may now use the reference |
| 442 | to access the various methods in the class. |
| 443 | |
| 444 | A reference can be blessed into a package with the following function: |
| 445 | |
| 446 | SV* sv_bless(SV* sv, HV* stash); |
| 447 | |
| 448 | The C<sv> argument must be a reference. The C<stash> argument specifies |
| 449 | which class the reference will belong to. See |
| 450 | L<Stashes and Globs> for information on converting class names into stashes. |
| 451 | |
| 452 | /* Still under construction */ |
| 453 | |
| 454 | Upgrades rv to reference if not already one. Creates new SV for rv to |
| 455 | point to. If C<classname> is non-null, the SV is blessed into the specified |
| 456 | class. SV is returned. |
| 457 | |
| 458 | SV* newSVrv(SV* rv, char* classname); |
| 459 | |
| 460 | Copies integer or double into an SV whose reference is C<rv>. SV is blessed |
| 461 | if C<classname> is non-null. |
| 462 | |
| 463 | SV* sv_setref_iv(SV* rv, char* classname, IV iv); |
| 464 | SV* sv_setref_nv(SV* rv, char* classname, NV iv); |
| 465 | |
| 466 | Copies the pointer value (I<the address, not the string!>) into an SV whose |
| 467 | reference is rv. SV is blessed if C<classname> is non-null. |
| 468 | |
| 469 | SV* sv_setref_pv(SV* rv, char* classname, PV iv); |
| 470 | |
| 471 | Copies string into an SV whose reference is C<rv>. Set length to 0 to let |
| 472 | Perl calculate the string length. SV is blessed if C<classname> is non-null. |
| 473 | |
| 474 | SV* sv_setref_pvn(SV* rv, char* classname, PV iv, int length); |
| 475 | |
| 476 | int sv_isa(SV* sv, char* name); |
| 477 | int sv_isobject(SV* sv); |
| 478 | |
| 479 | =head2 Creating New Variables |
| 480 | |
| 481 | To create a new Perl variable with an undef value which can be accessed from |
| 482 | your Perl script, use the following routines, depending on the variable type. |
| 483 | |
| 484 | SV* perl_get_sv("package::varname", TRUE); |
| 485 | AV* perl_get_av("package::varname", TRUE); |
| 486 | HV* perl_get_hv("package::varname", TRUE); |
| 487 | |
| 488 | Notice the use of TRUE as the second parameter. The new variable can now |
| 489 | be set, using the routines appropriate to the data type. |
| 490 | |
| 491 | There are additional macros whose values may be bitwise OR'ed with the |
| 492 | C<TRUE> argument to enable certain extra features. Those bits are: |
| 493 | |
| 494 | GV_ADDMULTI Marks the variable as multiply defined, thus preventing the |
| 495 | "Name <varname> used only once: possible typo" warning. |
| 496 | GV_ADDWARN Issues the warning "Had to create <varname> unexpectedly" if |
| 497 | the variable did not exist before the function was called. |
| 498 | |
| 499 | If you do not specify a package name, the variable is created in the current |
| 500 | package. |
| 501 | |
| 502 | =head2 Reference Counts and Mortality |
| 503 | |
| 504 | Perl uses an reference count-driven garbage collection mechanism. SVs, |
| 505 | AVs, or HVs (xV for short in the following) start their life with a |
| 506 | reference count of 1. If the reference count of an xV ever drops to 0, |
| 507 | then it will be destroyed and its memory made available for reuse. |
| 508 | |
| 509 | This normally doesn't happen at the Perl level unless a variable is |
| 510 | undef'ed or the last variable holding a reference to it is changed or |
| 511 | overwritten. At the internal level, however, reference counts can be |
| 512 | manipulated with the following macros: |
| 513 | |
| 514 | int SvREFCNT(SV* sv); |
| 515 | SV* SvREFCNT_inc(SV* sv); |
| 516 | void SvREFCNT_dec(SV* sv); |
| 517 | |
| 518 | However, there is one other function which manipulates the reference |
| 519 | count of its argument. The C<newRV_inc> function, you will recall, |
| 520 | creates a reference to the specified argument. As a side effect, |
| 521 | it increments the argument's reference count. If this is not what |
| 522 | you want, use C<newRV_noinc> instead. |
| 523 | |
| 524 | For example, imagine you want to return a reference from an XSUB function. |
| 525 | Inside the XSUB routine, you create an SV which initially has a reference |
| 526 | count of one. Then you call C<newRV_inc>, passing it the just-created SV. |
| 527 | This returns the reference as a new SV, but the reference count of the |
| 528 | SV you passed to C<newRV_inc> has been incremented to two. Now you |
| 529 | return the reference from the XSUB routine and forget about the SV. |
| 530 | But Perl hasn't! Whenever the returned reference is destroyed, the |
| 531 | reference count of the original SV is decreased to one and nothing happens. |
| 532 | The SV will hang around without any way to access it until Perl itself |
| 533 | terminates. This is a memory leak. |
| 534 | |
| 535 | The correct procedure, then, is to use C<newRV_noinc> instead of |
| 536 | C<newRV_inc>. Then, if and when the last reference is destroyed, |
| 537 | the reference count of the SV will go to zero and it will be destroyed, |
| 538 | stopping any memory leak. |
| 539 | |
| 540 | There are some convenience functions available that can help with the |
| 541 | destruction of xVs. These functions introduce the concept of "mortality". |
| 542 | An xV that is mortal has had its reference count marked to be decremented, |
| 543 | but not actually decremented, until "a short time later". Generally the |
| 544 | term "short time later" means a single Perl statement, such as a call to |
| 545 | an XSUB function. The actual determinant for when mortal xVs have their |
| 546 | reference count decremented depends on two macros, SAVETMPS and FREETMPS. |
| 547 | See L<perlcall> and L<perlxs> for more details on these macros. |
| 548 | |
| 549 | "Mortalization" then is at its simplest a deferred C<SvREFCNT_dec>. |
| 550 | However, if you mortalize a variable twice, the reference count will |
| 551 | later be decremented twice. |
| 552 | |
| 553 | You should be careful about creating mortal variables. Strange things |
| 554 | can happen if you make the same value mortal within multiple contexts, |
| 555 | or if you make a variable mortal multiple times. |
| 556 | |
| 557 | To create a mortal variable, use the functions: |
| 558 | |
| 559 | SV* sv_newmortal() |
| 560 | SV* sv_2mortal(SV*) |
| 561 | SV* sv_mortalcopy(SV*) |
| 562 | |
| 563 | The first call creates a mortal SV, the second converts an existing |
| 564 | SV to a mortal SV (and thus defers a call to C<SvREFCNT_dec>), and the |
| 565 | third creates a mortal copy of an existing SV. |
| 566 | |
| 567 | The mortal routines are not just for SVs -- AVs and HVs can be |
| 568 | made mortal by passing their address (type-casted to C<SV*>) to the |
| 569 | C<sv_2mortal> or C<sv_mortalcopy> routines. |
| 570 | |
| 571 | =head2 Stashes and Globs |
| 572 | |
| 573 | A "stash" is a hash that contains all of the different objects that |
| 574 | are contained within a package. Each key of the stash is a symbol |
| 575 | name (shared by all the different types of objects that have the same |
| 576 | name), and each value in the hash table is a GV (Glob Value). This GV |
| 577 | in turn contains references to the various objects of that name, |
| 578 | including (but not limited to) the following: |
| 579 | |
| 580 | Scalar Value |
| 581 | Array Value |
| 582 | Hash Value |
| 583 | File Handle |
| 584 | Directory Handle |
| 585 | Format |
| 586 | Subroutine |
| 587 | |
| 588 | There is a single stash called "defstash" that holds the items that exist |
| 589 | in the "main" package. To get at the items in other packages, append the |
| 590 | string "::" to the package name. The items in the "Foo" package are in |
| 591 | the stash "Foo::" in defstash. The items in the "Bar::Baz" package are |
| 592 | in the stash "Baz::" in "Bar::"'s stash. |
| 593 | |
| 594 | To get the stash pointer for a particular package, use the function: |
| 595 | |
| 596 | HV* gv_stashpv(char* name, I32 create) |
| 597 | HV* gv_stashsv(SV*, I32 create) |
| 598 | |
| 599 | The first function takes a literal string, the second uses the string stored |
| 600 | in the SV. Remember that a stash is just a hash table, so you get back an |
| 601 | C<HV*>. The C<create> flag will create a new package if it is set. |
| 602 | |
| 603 | The name that C<gv_stash*v> wants is the name of the package whose symbol table |
| 604 | you want. The default package is called C<main>. If you have multiply nested |
| 605 | packages, pass their names to C<gv_stash*v>, separated by C<::> as in the Perl |
| 606 | language itself. |
| 607 | |
| 608 | Alternately, if you have an SV that is a blessed reference, you can find |
| 609 | out the stash pointer by using: |
| 610 | |
| 611 | HV* SvSTASH(SvRV(SV*)); |
| 612 | |
| 613 | then use the following to get the package name itself: |
| 614 | |
| 615 | char* HvNAME(HV* stash); |
| 616 | |
| 617 | If you need to bless or re-bless an object you can use the following |
| 618 | function: |
| 619 | |
| 620 | SV* sv_bless(SV*, HV* stash) |
| 621 | |
| 622 | where the first argument, an C<SV*>, must be a reference, and the second |
| 623 | argument is a stash. The returned C<SV*> can now be used in the same way |
| 624 | as any other SV. |
| 625 | |
| 626 | For more information on references and blessings, consult L<perlref>. |
| 627 | |
| 628 | =head2 Double-Typed SVs |
| 629 | |
| 630 | Scalar variables normally contain only one type of value, an integer, |
| 631 | double, pointer, or reference. Perl will automatically convert the |
| 632 | actual scalar data from the stored type into the requested type. |
| 633 | |
| 634 | Some scalar variables contain more than one type of scalar data. For |
| 635 | example, the variable C<$!> contains either the numeric value of C<errno> |
| 636 | or its string equivalent from either C<strerror> or C<sys_errlist[]>. |
| 637 | |
| 638 | To force multiple data values into an SV, you must do two things: use the |
| 639 | C<sv_set*v> routines to add the additional scalar type, then set a flag |
| 640 | so that Perl will believe it contains more than one type of data. The |
| 641 | four macros to set the flags are: |
| 642 | |
| 643 | SvIOK_on |
| 644 | SvNOK_on |
| 645 | SvPOK_on |
| 646 | SvROK_on |
| 647 | |
| 648 | The particular macro you must use depends on which C<sv_set*v> routine |
| 649 | you called first. This is because every C<sv_set*v> routine turns on |
| 650 | only the bit for the particular type of data being set, and turns off |
| 651 | all the rest. |
| 652 | |
| 653 | For example, to create a new Perl variable called "dberror" that contains |
| 654 | both the numeric and descriptive string error values, you could use the |
| 655 | following code: |
| 656 | |
| 657 | extern int dberror; |
| 658 | extern char *dberror_list; |
| 659 | |
| 660 | SV* sv = perl_get_sv("dberror", TRUE); |
| 661 | sv_setiv(sv, (IV) dberror); |
| 662 | sv_setpv(sv, dberror_list[dberror]); |
| 663 | SvIOK_on(sv); |
| 664 | |
| 665 | If the order of C<sv_setiv> and C<sv_setpv> had been reversed, then the |
| 666 | macro C<SvPOK_on> would need to be called instead of C<SvIOK_on>. |
| 667 | |
| 668 | =head2 Magic Variables |
| 669 | |
| 670 | [This section still under construction. Ignore everything here. Post no |
| 671 | bills. Everything not permitted is forbidden.] |
| 672 | |
| 673 | Any SV may be magical, that is, it has special features that a normal |
| 674 | SV does not have. These features are stored in the SV structure in a |
| 675 | linked list of C<struct magic>'s, typedef'ed to C<MAGIC>. |
| 676 | |
| 677 | struct magic { |
| 678 | MAGIC* mg_moremagic; |
| 679 | MGVTBL* mg_virtual; |
| 680 | U16 mg_private; |
| 681 | char mg_type; |
| 682 | U8 mg_flags; |
| 683 | SV* mg_obj; |
| 684 | char* mg_ptr; |
| 685 | I32 mg_len; |
| 686 | }; |
| 687 | |
| 688 | Note this is current as of patchlevel 0, and could change at any time. |
| 689 | |
| 690 | =head2 Assigning Magic |
| 691 | |
| 692 | Perl adds magic to an SV using the sv_magic function: |
| 693 | |
| 694 | void sv_magic(SV* sv, SV* obj, int how, char* name, I32 namlen); |
| 695 | |
| 696 | The C<sv> argument is a pointer to the SV that is to acquire a new magical |
| 697 | feature. |
| 698 | |
| 699 | If C<sv> is not already magical, Perl uses the C<SvUPGRADE> macro to |
| 700 | set the C<SVt_PVMG> flag for the C<sv>. Perl then continues by adding |
| 701 | it to the beginning of the linked list of magical features. Any prior |
| 702 | entry of the same type of magic is deleted. Note that this can be |
| 703 | overridden, and multiple instances of the same type of magic can be |
| 704 | associated with an SV. |
| 705 | |
| 706 | The C<name> and C<namlen> arguments are used to associate a string with |
| 707 | the magic, typically the name of a variable. C<namlen> is stored in the |
| 708 | C<mg_len> field and if C<name> is non-null and C<namlen> >= 0 a malloc'd |
| 709 | copy of the name is stored in C<mg_ptr> field. |
| 710 | |
| 711 | The sv_magic function uses C<how> to determine which, if any, predefined |
| 712 | "Magic Virtual Table" should be assigned to the C<mg_virtual> field. |
| 713 | See the "Magic Virtual Table" section below. The C<how> argument is also |
| 714 | stored in the C<mg_type> field. |
| 715 | |
| 716 | The C<obj> argument is stored in the C<mg_obj> field of the C<MAGIC> |
| 717 | structure. If it is not the same as the C<sv> argument, the reference |
| 718 | count of the C<obj> object is incremented. If it is the same, or if |
| 719 | the C<how> argument is "#", or if it is a NULL pointer, then C<obj> is |
| 720 | merely stored, without the reference count being incremented. |
| 721 | |
| 722 | There is also a function to add magic to an C<HV>: |
| 723 | |
| 724 | void hv_magic(HV *hv, GV *gv, int how); |
| 725 | |
| 726 | This simply calls C<sv_magic> and coerces the C<gv> argument into an C<SV>. |
| 727 | |
| 728 | To remove the magic from an SV, call the function sv_unmagic: |
| 729 | |
| 730 | void sv_unmagic(SV *sv, int type); |
| 731 | |
| 732 | The C<type> argument should be equal to the C<how> value when the C<SV> |
| 733 | was initially made magical. |
| 734 | |
| 735 | =head2 Magic Virtual Tables |
| 736 | |
| 737 | The C<mg_virtual> field in the C<MAGIC> structure is a pointer to a |
| 738 | C<MGVTBL>, which is a structure of function pointers and stands for |
| 739 | "Magic Virtual Table" to handle the various operations that might be |
| 740 | applied to that variable. |
| 741 | |
| 742 | The C<MGVTBL> has five pointers to the following routine types: |
| 743 | |
| 744 | int (*svt_get)(SV* sv, MAGIC* mg); |
| 745 | int (*svt_set)(SV* sv, MAGIC* mg); |
| 746 | U32 (*svt_len)(SV* sv, MAGIC* mg); |
| 747 | int (*svt_clear)(SV* sv, MAGIC* mg); |
| 748 | int (*svt_free)(SV* sv, MAGIC* mg); |
| 749 | |
| 750 | This MGVTBL structure is set at compile-time in C<perl.h> and there are |
| 751 | currently 19 types (or 21 with overloading turned on). These different |
| 752 | structures contain pointers to various routines that perform additional |
| 753 | actions depending on which function is being called. |
| 754 | |
| 755 | Function pointer Action taken |
| 756 | ---------------- ------------ |
| 757 | svt_get Do something after the value of the SV is retrieved. |
| 758 | svt_set Do something after the SV is assigned a value. |
| 759 | svt_len Report on the SV's length. |
| 760 | svt_clear Clear something the SV represents. |
| 761 | svt_free Free any extra storage associated with the SV. |
| 762 | |
| 763 | For instance, the MGVTBL structure called C<vtbl_sv> (which corresponds |
| 764 | to an C<mg_type> of '\0') contains: |
| 765 | |
| 766 | { magic_get, magic_set, magic_len, 0, 0 } |
| 767 | |
| 768 | Thus, when an SV is determined to be magical and of type '\0', if a get |
| 769 | operation is being performed, the routine C<magic_get> is called. All |
| 770 | the various routines for the various magical types begin with C<magic_>. |
| 771 | |
| 772 | The current kinds of Magic Virtual Tables are: |
| 773 | |
| 774 | mg_type MGVTBL Type of magic |
| 775 | ------- ------ ---------------------------- |
| 776 | \0 vtbl_sv Special scalar variable |
| 777 | A vtbl_amagic %OVERLOAD hash |
| 778 | a vtbl_amagicelem %OVERLOAD hash element |
| 779 | c (none) Holds overload table (AMT) on stash |
| 780 | B vtbl_bm Boyer-Moore (fast string search) |
| 781 | E vtbl_env %ENV hash |
| 782 | e vtbl_envelem %ENV hash element |
| 783 | f vtbl_fm Formline ('compiled' format) |
| 784 | g vtbl_mglob m//g target / study()ed string |
| 785 | I vtbl_isa @ISA array |
| 786 | i vtbl_isaelem @ISA array element |
| 787 | k vtbl_nkeys scalar(keys()) lvalue |
| 788 | L (none) Debugger %_<filename |
| 789 | l vtbl_dbline Debugger %_<filename element |
| 790 | o vtbl_collxfrm Locale transformation |
| 791 | P vtbl_pack Tied array or hash |
| 792 | p vtbl_packelem Tied array or hash element |
| 793 | q vtbl_packelem Tied scalar or handle |
| 794 | S vtbl_sig %SIG hash |
| 795 | s vtbl_sigelem %SIG hash element |
| 796 | t vtbl_taint Taintedness |
| 797 | U vtbl_uvar Available for use by extensions |
| 798 | v vtbl_vec vec() lvalue |
| 799 | x vtbl_substr substr() lvalue |
| 800 | y vtbl_defelem Shadow "foreach" iterator variable / |
| 801 | smart parameter vivification |
| 802 | * vtbl_glob GV (typeglob) |
| 803 | # vtbl_arylen Array length ($#ary) |
| 804 | . vtbl_pos pos() lvalue |
| 805 | ~ (none) Available for use by extensions |
| 806 | |
| 807 | When an uppercase and lowercase letter both exist in the table, then the |
| 808 | uppercase letter is used to represent some kind of composite type (a list |
| 809 | or a hash), and the lowercase letter is used to represent an element of |
| 810 | that composite type. |
| 811 | |
| 812 | The '~' and 'U' magic types are defined specifically for use by |
| 813 | extensions and will not be used by perl itself. Extensions can use |
| 814 | '~' magic to 'attach' private information to variables (typically |
| 815 | objects). This is especially useful because there is no way for |
| 816 | normal perl code to corrupt this private information (unlike using |
| 817 | extra elements of a hash object). |
| 818 | |
| 819 | Similarly, 'U' magic can be used much like tie() to call a C function |
| 820 | any time a scalar's value is used or changed. The C<MAGIC>'s |
| 821 | C<mg_ptr> field points to a C<ufuncs> structure: |
| 822 | |
| 823 | struct ufuncs { |
| 824 | I32 (*uf_val)(IV, SV*); |
| 825 | I32 (*uf_set)(IV, SV*); |
| 826 | IV uf_index; |
| 827 | }; |
| 828 | |
| 829 | When the SV is read from or written to, the C<uf_val> or C<uf_set> |
| 830 | function will be called with C<uf_index> as the first arg and a |
| 831 | pointer to the SV as the second. |
| 832 | |
| 833 | Note that because multiple extensions may be using '~' or 'U' magic, |
| 834 | it is important for extensions to take extra care to avoid conflict. |
| 835 | Typically only using the magic on objects blessed into the same class |
| 836 | as the extension is sufficient. For '~' magic, it may also be |
| 837 | appropriate to add an I32 'signature' at the top of the private data |
| 838 | area and check that. |
| 839 | |
| 840 | Also note that most of the C<sv_set*()> functions that modify scalars do |
| 841 | B<not> invoke 'set' magic on their targets. This must be done by the user |
| 842 | either by calling the C<SvSETMAGIC()> macro after calling these functions, |
| 843 | or by using one of the C<SvSetMagic*()> macros. Similarly, generic C code |
| 844 | must call the C<SvGETMAGIC()> macro to invoke any 'get' magic if they use |
| 845 | an SV obtained from external sources in functions that don't handle magic. |
| 846 | L<API LISTING> later in this document identifies such macros and functions. |
| 847 | For example, calls to the C<sv_cat*()> functions typically need to be |
| 848 | followed by C<SvSETMAGIC()>, but they don't need a prior C<SvGETMAGIC()> |
| 849 | since their implementation handles 'get' magic. |
| 850 | |
| 851 | =head2 Finding Magic |
| 852 | |
| 853 | MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */ |
| 854 | |
| 855 | This routine returns a pointer to the C<MAGIC> structure stored in the SV. |
| 856 | If the SV does not have that magical feature, C<NULL> is returned. Also, |
| 857 | if the SV is not of type SVt_PVMG, Perl may core dump. |
| 858 | |
| 859 | int mg_copy(SV* sv, SV* nsv, char* key, STRLEN klen); |
| 860 | |
| 861 | This routine checks to see what types of magic C<sv> has. If the mg_type |
| 862 | field is an uppercase letter, then the mg_obj is copied to C<nsv>, but |
| 863 | the mg_type field is changed to be the lowercase letter. |
| 864 | |
| 865 | =head2 Understanding the Magic of Tied Hashes and Arrays |
| 866 | |
| 867 | Tied hashes and arrays are magical beasts of the 'P' magic type. |
| 868 | |
| 869 | WARNING: As of the 5.004 release, proper usage of the array and hash |
| 870 | access functions requires understanding a few caveats. Some |
| 871 | of these caveats are actually considered bugs in the API, to be fixed |
| 872 | in later releases, and are bracketed with [MAYCHANGE] below. If |
| 873 | you find yourself actually applying such information in this section, be |
| 874 | aware that the behavior may change in the future, umm, without warning. |
| 875 | |
| 876 | The C<av_store> function, when given a tied array argument, merely |
| 877 | copies the magic of the array onto the value to be "stored", using |
| 878 | C<mg_copy>. It may also return NULL, indicating that the value did not |
| 879 | actually need to be stored in the array. [MAYCHANGE] After a call to |
| 880 | C<av_store> on a tied array, the caller will usually need to call |
| 881 | C<mg_set(val)> to actually invoke the perl level "STORE" method on the |
| 882 | TIEARRAY object. If C<av_store> did return NULL, a call to |
| 883 | C<SvREFCNT_dec(val)> will also be usually necessary to avoid a memory |
| 884 | leak. [/MAYCHANGE] |
| 885 | |
| 886 | The previous paragraph is applicable verbatim to tied hash access using the |
| 887 | C<hv_store> and C<hv_store_ent> functions as well. |
| 888 | |
| 889 | C<av_fetch> and the corresponding hash functions C<hv_fetch> and |
| 890 | C<hv_fetch_ent> actually return an undefined mortal value whose magic |
| 891 | has been initialized using C<mg_copy>. Note the value so returned does not |
| 892 | need to be deallocated, as it is already mortal. [MAYCHANGE] But you will |
| 893 | need to call C<mg_get()> on the returned value in order to actually invoke |
| 894 | the perl level "FETCH" method on the underlying TIE object. Similarly, |
| 895 | you may also call C<mg_set()> on the return value after possibly assigning |
| 896 | a suitable value to it using C<sv_setsv>, which will invoke the "STORE" |
| 897 | method on the TIE object. [/MAYCHANGE] |
| 898 | |
| 899 | [MAYCHANGE] |
| 900 | In other words, the array or hash fetch/store functions don't really |
| 901 | fetch and store actual values in the case of tied arrays and hashes. They |
| 902 | merely call C<mg_copy> to attach magic to the values that were meant to be |
| 903 | "stored" or "fetched". Later calls to C<mg_get> and C<mg_set> actually |
| 904 | do the job of invoking the TIE methods on the underlying objects. Thus |
| 905 | the magic mechanism currently implements a kind of lazy access to arrays |
| 906 | and hashes. |
| 907 | |
| 908 | Currently (as of perl version 5.004), use of the hash and array access |
| 909 | functions requires the user to be aware of whether they are operating on |
| 910 | "normal" hashes and arrays, or on their tied variants. The API may be |
| 911 | changed to provide more transparent access to both tied and normal data |
| 912 | types in future versions. |
| 913 | [/MAYCHANGE] |
| 914 | |
| 915 | You would do well to understand that the TIEARRAY and TIEHASH interfaces |
| 916 | are mere sugar to invoke some perl method calls while using the uniform hash |
| 917 | and array syntax. The use of this sugar imposes some overhead (typically |
| 918 | about two to four extra opcodes per FETCH/STORE operation, in addition to |
| 919 | the creation of all the mortal variables required to invoke the methods). |
| 920 | This overhead will be comparatively small if the TIE methods are themselves |
| 921 | substantial, but if they are only a few statements long, the overhead |
| 922 | will not be insignificant. |
| 923 | |
| 924 | =head2 Localizing changes |
| 925 | |
| 926 | Perl has a very handy construction |
| 927 | |
| 928 | { |
| 929 | local $var = 2; |
| 930 | ... |
| 931 | } |
| 932 | |
| 933 | This construction is I<approximately> equivalent to |
| 934 | |
| 935 | { |
| 936 | my $oldvar = $var; |
| 937 | $var = 2; |
| 938 | ... |
| 939 | $var = $oldvar; |
| 940 | } |
| 941 | |
| 942 | The biggest difference is that the first construction would |
| 943 | reinstate the initial value of $var, irrespective of how control exits |
| 944 | the block: C<goto>, C<return>, C<die>/C<eval> etc. It is a little bit |
| 945 | more efficient as well. |
| 946 | |
| 947 | There is a way to achieve a similar task from C via Perl API: create a |
| 948 | I<pseudo-block>, and arrange for some changes to be automatically |
| 949 | undone at the end of it, either explicit, or via a non-local exit (via |
| 950 | die()). A I<block>-like construct is created by a pair of |
| 951 | C<ENTER>/C<LEAVE> macros (see L<perlcall/EXAMPLE/"Returning a |
| 952 | Scalar">). Such a construct may be created specially for some |
| 953 | important localized task, or an existing one (like boundaries of |
| 954 | enclosing Perl subroutine/block, or an existing pair for freeing TMPs) |
| 955 | may be used. (In the second case the overhead of additional |
| 956 | localization must be almost negligible.) Note that any XSUB is |
| 957 | automatically enclosed in an C<ENTER>/C<LEAVE> pair. |
| 958 | |
| 959 | Inside such a I<pseudo-block> the following service is available: |
| 960 | |
| 961 | =over |
| 962 | |
| 963 | =item C<SAVEINT(int i)> |
| 964 | |
| 965 | =item C<SAVEIV(IV i)> |
| 966 | |
| 967 | =item C<SAVEI32(I32 i)> |
| 968 | |
| 969 | =item C<SAVELONG(long i)> |
| 970 | |
| 971 | These macros arrange things to restore the value of integer variable |
| 972 | C<i> at the end of enclosing I<pseudo-block>. |
| 973 | |
| 974 | =item C<SAVESPTR(s)> |
| 975 | |
| 976 | =item C<SAVEPPTR(p)> |
| 977 | |
| 978 | These macros arrange things to restore the value of pointers C<s> and |
| 979 | C<p>. C<s> must be a pointer of a type which survives conversion to |
| 980 | C<SV*> and back, C<p> should be able to survive conversion to C<char*> |
| 981 | and back. |
| 982 | |
| 983 | =item C<SAVEFREESV(SV *sv)> |
| 984 | |
| 985 | The refcount of C<sv> would be decremented at the end of |
| 986 | I<pseudo-block>. This is similar to C<sv_2mortal>, which should (?) be |
| 987 | used instead. |
| 988 | |
| 989 | =item C<SAVEFREEOP(OP *op)> |
| 990 | |
| 991 | The C<OP *> is op_free()ed at the end of I<pseudo-block>. |
| 992 | |
| 993 | =item C<SAVEFREEPV(p)> |
| 994 | |
| 995 | The chunk of memory which is pointed to by C<p> is Safefree()ed at the |
| 996 | end of I<pseudo-block>. |
| 997 | |
| 998 | =item C<SAVECLEARSV(SV *sv)> |
| 999 | |
| 1000 | Clears a slot in the current scratchpad which corresponds to C<sv> at |
| 1001 | the end of I<pseudo-block>. |
| 1002 | |
| 1003 | =item C<SAVEDELETE(HV *hv, char *key, I32 length)> |
| 1004 | |
| 1005 | The key C<key> of C<hv> is deleted at the end of I<pseudo-block>. The |
| 1006 | string pointed to by C<key> is Safefree()ed. If one has a I<key> in |
| 1007 | short-lived storage, the corresponding string may be reallocated like |
| 1008 | this: |
| 1009 | |
| 1010 | SAVEDELETE(defstash, savepv(tmpbuf), strlen(tmpbuf)); |
| 1011 | |
| 1012 | =item C<SAVEDESTRUCTOR(f,p)> |
| 1013 | |
| 1014 | At the end of I<pseudo-block> the function C<f> is called with the |
| 1015 | only argument (of type C<void*>) C<p>. |
| 1016 | |
| 1017 | =item C<SAVESTACK_POS()> |
| 1018 | |
| 1019 | The current offset on the Perl internal stack (cf. C<SP>) is restored |
| 1020 | at the end of I<pseudo-block>. |
| 1021 | |
| 1022 | =back |
| 1023 | |
| 1024 | The following API list contains functions, thus one needs to |
| 1025 | provide pointers to the modifiable data explicitly (either C pointers, |
| 1026 | or Perlish C<GV *>s). Where the above macros take C<int>, a similar |
| 1027 | function takes C<int *>. |
| 1028 | |
| 1029 | =over |
| 1030 | |
| 1031 | =item C<SV* save_scalar(GV *gv)> |
| 1032 | |
| 1033 | Equivalent to Perl code C<local $gv>. |
| 1034 | |
| 1035 | =item C<AV* save_ary(GV *gv)> |
| 1036 | |
| 1037 | =item C<HV* save_hash(GV *gv)> |
| 1038 | |
| 1039 | Similar to C<save_scalar>, but localize C<@gv> and C<%gv>. |
| 1040 | |
| 1041 | =item C<void save_item(SV *item)> |
| 1042 | |
| 1043 | Duplicates the current value of C<SV>, on the exit from the current |
| 1044 | C<ENTER>/C<LEAVE> I<pseudo-block> will restore the value of C<SV> |
| 1045 | using the stored value. |
| 1046 | |
| 1047 | =item C<void save_list(SV **sarg, I32 maxsarg)> |
| 1048 | |
| 1049 | A variant of C<save_item> which takes multiple arguments via an array |
| 1050 | C<sarg> of C<SV*> of length C<maxsarg>. |
| 1051 | |
| 1052 | =item C<SV* save_svref(SV **sptr)> |
| 1053 | |
| 1054 | Similar to C<save_scalar>, but will reinstate a C<SV *>. |
| 1055 | |
| 1056 | =item C<void save_aptr(AV **aptr)> |
| 1057 | |
| 1058 | =item C<void save_hptr(HV **hptr)> |
| 1059 | |
| 1060 | Similar to C<save_svref>, but localize C<AV *> and C<HV *>. |
| 1061 | |
| 1062 | =back |
| 1063 | |
| 1064 | The C<Alias> module implements localization of the basic types within the |
| 1065 | I<caller's scope>. People who are interested in how to localize things in |
| 1066 | the containing scope should take a look there too. |
| 1067 | |
| 1068 | =head1 Subroutines |
| 1069 | |
| 1070 | =head2 XSUBs and the Argument Stack |
| 1071 | |
| 1072 | The XSUB mechanism is a simple way for Perl programs to access C subroutines. |
| 1073 | An XSUB routine will have a stack that contains the arguments from the Perl |
| 1074 | program, and a way to map from the Perl data structures to a C equivalent. |
| 1075 | |
| 1076 | The stack arguments are accessible through the C<ST(n)> macro, which returns |
| 1077 | the C<n>'th stack argument. Argument 0 is the first argument passed in the |
| 1078 | Perl subroutine call. These arguments are C<SV*>, and can be used anywhere |
| 1079 | an C<SV*> is used. |
| 1080 | |
| 1081 | Most of the time, output from the C routine can be handled through use of |
| 1082 | the RETVAL and OUTPUT directives. However, there are some cases where the |
| 1083 | argument stack is not already long enough to handle all the return values. |
| 1084 | An example is the POSIX tzname() call, which takes no arguments, but returns |
| 1085 | two, the local time zone's standard and summer time abbreviations. |
| 1086 | |
| 1087 | To handle this situation, the PPCODE directive is used and the stack is |
| 1088 | extended using the macro: |
| 1089 | |
| 1090 | EXTEND(sp, num); |
| 1091 | |
| 1092 | where C<sp> is the stack pointer, and C<num> is the number of elements the |
| 1093 | stack should be extended by. |
| 1094 | |
| 1095 | Now that there is room on the stack, values can be pushed on it using the |
| 1096 | macros to push IVs, doubles, strings, and SV pointers respectively: |
| 1097 | |
| 1098 | PUSHi(IV) |
| 1099 | PUSHn(double) |
| 1100 | PUSHp(char*, I32) |
| 1101 | PUSHs(SV*) |
| 1102 | |
| 1103 | And now the Perl program calling C<tzname>, the two values will be assigned |
| 1104 | as in: |
| 1105 | |
| 1106 | ($standard_abbrev, $summer_abbrev) = POSIX::tzname; |
| 1107 | |
| 1108 | An alternate (and possibly simpler) method to pushing values on the stack is |
| 1109 | to use the macros: |
| 1110 | |
| 1111 | XPUSHi(IV) |
| 1112 | XPUSHn(double) |
| 1113 | XPUSHp(char*, I32) |
| 1114 | XPUSHs(SV*) |
| 1115 | |
| 1116 | These macros automatically adjust the stack for you, if needed. Thus, you |
| 1117 | do not need to call C<EXTEND> to extend the stack. |
| 1118 | |
| 1119 | For more information, consult L<perlxs> and L<perlxstut>. |
| 1120 | |
| 1121 | =head2 Calling Perl Routines from within C Programs |
| 1122 | |
| 1123 | There are four routines that can be used to call a Perl subroutine from |
| 1124 | within a C program. These four are: |
| 1125 | |
| 1126 | I32 perl_call_sv(SV*, I32); |
| 1127 | I32 perl_call_pv(char*, I32); |
| 1128 | I32 perl_call_method(char*, I32); |
| 1129 | I32 perl_call_argv(char*, I32, register char**); |
| 1130 | |
| 1131 | The routine most often used is C<perl_call_sv>. The C<SV*> argument |
| 1132 | contains either the name of the Perl subroutine to be called, or a |
| 1133 | reference to the subroutine. The second argument consists of flags |
| 1134 | that control the context in which the subroutine is called, whether |
| 1135 | or not the subroutine is being passed arguments, how errors should be |
| 1136 | trapped, and how to treat return values. |
| 1137 | |
| 1138 | All four routines return the number of arguments that the subroutine returned |
| 1139 | on the Perl stack. |
| 1140 | |
| 1141 | When using any of these routines (except C<perl_call_argv>), the programmer |
| 1142 | must manipulate the Perl stack. These include the following macros and |
| 1143 | functions: |
| 1144 | |
| 1145 | dSP |
| 1146 | PUSHMARK() |
| 1147 | PUTBACK |
| 1148 | SPAGAIN |
| 1149 | ENTER |
| 1150 | SAVETMPS |
| 1151 | FREETMPS |
| 1152 | LEAVE |
| 1153 | XPUSH*() |
| 1154 | POP*() |
| 1155 | |
| 1156 | For a detailed description of calling conventions from C to Perl, |
| 1157 | consult L<perlcall>. |
| 1158 | |
| 1159 | =head2 Memory Allocation |
| 1160 | |
| 1161 | It is suggested that you use the version of malloc that is distributed |
| 1162 | with Perl. It keeps pools of various sizes of unallocated memory in |
| 1163 | order to satisfy allocation requests more quickly. However, on some |
| 1164 | platforms, it may cause spurious malloc or free errors. |
| 1165 | |
| 1166 | New(x, pointer, number, type); |
| 1167 | Newc(x, pointer, number, type, cast); |
| 1168 | Newz(x, pointer, number, type); |
| 1169 | |
| 1170 | These three macros are used to initially allocate memory. |
| 1171 | |
| 1172 | The first argument C<x> was a "magic cookie" that was used to keep track |
| 1173 | of who called the macro, to help when debugging memory problems. However, |
| 1174 | the current code makes no use of this feature (most Perl developers now |
| 1175 | use run-time memory checkers), so this argument can be any number. |
| 1176 | |
| 1177 | The second argument C<pointer> should be the name of a variable that will |
| 1178 | point to the newly allocated memory. |
| 1179 | |
| 1180 | The third and fourth arguments C<number> and C<type> specify how many of |
| 1181 | the specified type of data structure should be allocated. The argument |
| 1182 | C<type> is passed to C<sizeof>. The final argument to C<Newc>, C<cast>, |
| 1183 | should be used if the C<pointer> argument is different from the C<type> |
| 1184 | argument. |
| 1185 | |
| 1186 | Unlike the C<New> and C<Newc> macros, the C<Newz> macro calls C<memzero> |
| 1187 | to zero out all the newly allocated memory. |
| 1188 | |
| 1189 | Renew(pointer, number, type); |
| 1190 | Renewc(pointer, number, type, cast); |
| 1191 | Safefree(pointer) |
| 1192 | |
| 1193 | These three macros are used to change a memory buffer size or to free a |
| 1194 | piece of memory no longer needed. The arguments to C<Renew> and C<Renewc> |
| 1195 | match those of C<New> and C<Newc> with the exception of not needing the |
| 1196 | "magic cookie" argument. |
| 1197 | |
| 1198 | Move(source, dest, number, type); |
| 1199 | Copy(source, dest, number, type); |
| 1200 | Zero(dest, number, type); |
| 1201 | |
| 1202 | These three macros are used to move, copy, or zero out previously allocated |
| 1203 | memory. The C<source> and C<dest> arguments point to the source and |
| 1204 | destination starting points. Perl will move, copy, or zero out C<number> |
| 1205 | instances of the size of the C<type> data structure (using the C<sizeof> |
| 1206 | function). |
| 1207 | |
| 1208 | =head2 PerlIO |
| 1209 | |
| 1210 | The most recent development releases of Perl has been experimenting with |
| 1211 | removing Perl's dependency on the "normal" standard I/O suite and allowing |
| 1212 | other stdio implementations to be used. This involves creating a new |
| 1213 | abstraction layer that then calls whichever implementation of stdio Perl |
| 1214 | was compiled with. All XSUBs should now use the functions in the PerlIO |
| 1215 | abstraction layer and not make any assumptions about what kind of stdio |
| 1216 | is being used. |
| 1217 | |
| 1218 | For a complete description of the PerlIO abstraction, consult L<perlapio>. |
| 1219 | |
| 1220 | =head2 Putting a C value on Perl stack |
| 1221 | |
| 1222 | A lot of opcodes (this is an elementary operation in the internal perl |
| 1223 | stack machine) put an SV* on the stack. However, as an optimization |
| 1224 | the corresponding SV is (usually) not recreated each time. The opcodes |
| 1225 | reuse specially assigned SVs (I<target>s) which are (as a corollary) |
| 1226 | not constantly freed/created. |
| 1227 | |
| 1228 | Each of the targets is created only once (but see |
| 1229 | L<Scratchpads and recursion> below), and when an opcode needs to put |
| 1230 | an integer, a double, or a string on stack, it just sets the |
| 1231 | corresponding parts of its I<target> and puts the I<target> on stack. |
| 1232 | |
| 1233 | The macro to put this target on stack is C<PUSHTARG>, and it is |
| 1234 | directly used in some opcodes, as well as indirectly in zillions of |
| 1235 | others, which use it via C<(X)PUSH[pni]>. |
| 1236 | |
| 1237 | =head2 Scratchpads |
| 1238 | |
| 1239 | The question remains on when the SVs which are I<target>s for opcodes |
| 1240 | are created. The answer is that they are created when the current unit -- |
| 1241 | a subroutine or a file (for opcodes for statements outside of |
| 1242 | subroutines) -- is compiled. During this time a special anonymous Perl |
| 1243 | array is created, which is called a scratchpad for the current |
| 1244 | unit. |
| 1245 | |
| 1246 | A scratchpad keeps SVs which are lexicals for the current unit and are |
| 1247 | targets for opcodes. One can deduce that an SV lives on a scratchpad |
| 1248 | by looking on its flags: lexicals have C<SVs_PADMY> set, and |
| 1249 | I<target>s have C<SVs_PADTMP> set. |
| 1250 | |
| 1251 | The correspondence between OPs and I<target>s is not 1-to-1. Different |
| 1252 | OPs in the compile tree of the unit can use the same target, if this |
| 1253 | would not conflict with the expected life of the temporary. |
| 1254 | |
| 1255 | =head2 Scratchpads and recursion |
| 1256 | |
| 1257 | In fact it is not 100% true that a compiled unit contains a pointer to |
| 1258 | the scratchpad AV. In fact it contains a pointer to an AV of |
| 1259 | (initially) one element, and this element is the scratchpad AV. Why do |
| 1260 | we need an extra level of indirection? |
| 1261 | |
| 1262 | The answer is B<recursion>, and maybe (sometime soon) B<threads>. Both |
| 1263 | these can create several execution pointers going into the same |
| 1264 | subroutine. For the subroutine-child not write over the temporaries |
| 1265 | for the subroutine-parent (lifespan of which covers the call to the |
| 1266 | child), the parent and the child should have different |
| 1267 | scratchpads. (I<And> the lexicals should be separate anyway!) |
| 1268 | |
| 1269 | So each subroutine is born with an array of scratchpads (of length 1). |
| 1270 | On each entry to the subroutine it is checked that the current |
| 1271 | depth of the recursion is not more than the length of this array, and |
| 1272 | if it is, new scratchpad is created and pushed into the array. |
| 1273 | |
| 1274 | The I<target>s on this scratchpad are C<undef>s, but they are already |
| 1275 | marked with correct flags. |
| 1276 | |
| 1277 | =head1 Compiled code |
| 1278 | |
| 1279 | =head2 Code tree |
| 1280 | |
| 1281 | Here we describe the internal form your code is converted to by |
| 1282 | Perl. Start with a simple example: |
| 1283 | |
| 1284 | $a = $b + $c; |
| 1285 | |
| 1286 | This is converted to a tree similar to this one: |
| 1287 | |
| 1288 | assign-to |
| 1289 | / \ |
| 1290 | + $a |
| 1291 | / \ |
| 1292 | $b $c |
| 1293 | |
| 1294 | (but slightly more complicated). This tree reflect the way Perl |
| 1295 | parsed your code, but has nothing to do with the execution order. |
| 1296 | There is an additional "thread" going through the nodes of the tree |
| 1297 | which shows the order of execution of the nodes. In our simplified |
| 1298 | example above it looks like: |
| 1299 | |
| 1300 | $b ---> $c ---> + ---> $a ---> assign-to |
| 1301 | |
| 1302 | But with the actual compile tree for C<$a = $b + $c> it is different: |
| 1303 | some nodes I<optimized away>. As a corollary, though the actual tree |
| 1304 | contains more nodes than our simplified example, the execution order |
| 1305 | is the same as in our example. |
| 1306 | |
| 1307 | =head2 Examining the tree |
| 1308 | |
| 1309 | If you have your perl compiled for debugging (usually done with C<-D |
| 1310 | optimize=-g> on C<Configure> command line), you may examine the |
| 1311 | compiled tree by specifying C<-Dx> on the Perl command line. The |
| 1312 | output takes several lines per node, and for C<$b+$c> it looks like |
| 1313 | this: |
| 1314 | |
| 1315 | 5 TYPE = add ===> 6 |
| 1316 | TARG = 1 |
| 1317 | FLAGS = (SCALAR,KIDS) |
| 1318 | { |
| 1319 | TYPE = null ===> (4) |
| 1320 | (was rv2sv) |
| 1321 | FLAGS = (SCALAR,KIDS) |
| 1322 | { |
| 1323 | 3 TYPE = gvsv ===> 4 |
| 1324 | FLAGS = (SCALAR) |
| 1325 | GV = main::b |
| 1326 | } |
| 1327 | } |
| 1328 | { |
| 1329 | TYPE = null ===> (5) |
| 1330 | (was rv2sv) |
| 1331 | FLAGS = (SCALAR,KIDS) |
| 1332 | { |
| 1333 | 4 TYPE = gvsv ===> 5 |
| 1334 | FLAGS = (SCALAR) |
| 1335 | GV = main::c |
| 1336 | } |
| 1337 | } |
| 1338 | |
| 1339 | This tree has 5 nodes (one per C<TYPE> specifier), only 3 of them are |
| 1340 | not optimized away (one per number in the left column). The immediate |
| 1341 | children of the given node correspond to C<{}> pairs on the same level |
| 1342 | of indentation, thus this listing corresponds to the tree: |
| 1343 | |
| 1344 | add |
| 1345 | / \ |
| 1346 | null null |
| 1347 | | | |
| 1348 | gvsv gvsv |
| 1349 | |
| 1350 | The execution order is indicated by C<===E<gt>> marks, thus it is C<3 |
| 1351 | 4 5 6> (node C<6> is not included into above listing), i.e., |
| 1352 | C<gvsv gvsv add whatever>. |
| 1353 | |
| 1354 | =head2 Compile pass 1: check routines |
| 1355 | |
| 1356 | The tree is created by the I<pseudo-compiler> while yacc code feeds it |
| 1357 | the constructions it recognizes. Since yacc works bottom-up, so does |
| 1358 | the first pass of perl compilation. |
| 1359 | |
| 1360 | What makes this pass interesting for perl developers is that some |
| 1361 | optimization may be performed on this pass. This is optimization by |
| 1362 | so-called I<check routines>. The correspondence between node names |
| 1363 | and corresponding check routines is described in F<opcode.pl> (do not |
| 1364 | forget to run C<make regen_headers> if you modify this file). |
| 1365 | |
| 1366 | A check routine is called when the node is fully constructed except |
| 1367 | for the execution-order thread. Since at this time there is no |
| 1368 | back-links to the currently constructed node, one can do most any |
| 1369 | operation to the top-level node, including freeing it and/or creating |
| 1370 | new nodes above/below it. |
| 1371 | |
| 1372 | The check routine returns the node which should be inserted into the |
| 1373 | tree (if the top-level node was not modified, check routine returns |
| 1374 | its argument). |
| 1375 | |
| 1376 | By convention, check routines have names C<ck_*>. They are usually |
| 1377 | called from C<new*OP> subroutines (or C<convert>) (which in turn are |
| 1378 | called from F<perly.y>). |
| 1379 | |
| 1380 | =head2 Compile pass 1a: constant folding |
| 1381 | |
| 1382 | Immediately after the check routine is called the returned node is |
| 1383 | checked for being compile-time executable. If it is (the value is |
| 1384 | judged to be constant) it is immediately executed, and a I<constant> |
| 1385 | node with the "return value" of the corresponding subtree is |
| 1386 | substituted instead. The subtree is deleted. |
| 1387 | |
| 1388 | If constant folding was not performed, the execution-order thread is |
| 1389 | created. |
| 1390 | |
| 1391 | =head2 Compile pass 2: context propagation |
| 1392 | |
| 1393 | When a context for a part of compile tree is known, it is propagated |
| 1394 | down through the tree. Aat this time the context can have 5 values |
| 1395 | (instead of 2 for runtime context): void, boolean, scalar, list, and |
| 1396 | lvalue. In contrast with the pass 1 this pass is processed from top |
| 1397 | to bottom: a node's context determines the context for its children. |
| 1398 | |
| 1399 | Additional context-dependent optimizations are performed at this time. |
| 1400 | Since at this moment the compile tree contains back-references (via |
| 1401 | "thread" pointers), nodes cannot be free()d now. To allow |
| 1402 | optimized-away nodes at this stage, such nodes are null()ified instead |
| 1403 | of free()ing (i.e. their type is changed to OP_NULL). |
| 1404 | |
| 1405 | =head2 Compile pass 3: peephole optimization |
| 1406 | |
| 1407 | After the compile tree for a subroutine (or for an C<eval> or a file) |
| 1408 | is created, an additional pass over the code is performed. This pass |
| 1409 | is neither top-down or bottom-up, but in the execution order (with |
| 1410 | additional compilications for conditionals). These optimizations are |
| 1411 | done in the subroutine peep(). Optimizations performed at this stage |
| 1412 | are subject to the same restrictions as in the pass 2. |
| 1413 | |
| 1414 | =head1 API LISTING |
| 1415 | |
| 1416 | This is a listing of functions, macros, flags, and variables that may be |
| 1417 | useful to extension writers or that may be found while reading other |
| 1418 | extensions. |
| 1419 | |
| 1420 | =over 8 |
| 1421 | |
| 1422 | =item AvFILL |
| 1423 | |
| 1424 | Same as C<av_len>. |
| 1425 | |
| 1426 | =item av_clear |
| 1427 | |
| 1428 | Clears an array, making it empty. Does not free the memory used by the |
| 1429 | array itself. |
| 1430 | |
| 1431 | void av_clear _((AV* ar)); |
| 1432 | |
| 1433 | =item av_extend |
| 1434 | |
| 1435 | Pre-extend an array. The C<key> is the index to which the array should be |
| 1436 | extended. |
| 1437 | |
| 1438 | void av_extend _((AV* ar, I32 key)); |
| 1439 | |
| 1440 | =item av_fetch |
| 1441 | |
| 1442 | Returns the SV at the specified index in the array. The C<key> is the |
| 1443 | index. If C<lval> is set then the fetch will be part of a store. Check |
| 1444 | that the return value is non-null before dereferencing it to a C<SV*>. |
| 1445 | |
| 1446 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 1447 | information on how to use this function on tied arrays. |
| 1448 | |
| 1449 | SV** av_fetch _((AV* ar, I32 key, I32 lval)); |
| 1450 | |
| 1451 | =item av_len |
| 1452 | |
| 1453 | Returns the highest index in the array. Returns -1 if the array is empty. |
| 1454 | |
| 1455 | I32 av_len _((AV* ar)); |
| 1456 | |
| 1457 | =item av_make |
| 1458 | |
| 1459 | Creates a new AV and populates it with a list of SVs. The SVs are copied |
| 1460 | into the array, so they may be freed after the call to av_make. The new AV |
| 1461 | will have a reference count of 1. |
| 1462 | |
| 1463 | AV* av_make _((I32 size, SV** svp)); |
| 1464 | |
| 1465 | =item av_pop |
| 1466 | |
| 1467 | Pops an SV off the end of the array. Returns C<&sv_undef> if the array is |
| 1468 | empty. |
| 1469 | |
| 1470 | SV* av_pop _((AV* ar)); |
| 1471 | |
| 1472 | =item av_push |
| 1473 | |
| 1474 | Pushes an SV onto the end of the array. The array will grow automatically |
| 1475 | to accommodate the addition. |
| 1476 | |
| 1477 | void av_push _((AV* ar, SV* val)); |
| 1478 | |
| 1479 | =item av_shift |
| 1480 | |
| 1481 | Shifts an SV off the beginning of the array. |
| 1482 | |
| 1483 | SV* av_shift _((AV* ar)); |
| 1484 | |
| 1485 | =item av_store |
| 1486 | |
| 1487 | Stores an SV in an array. The array index is specified as C<key>. The |
| 1488 | return value will be NULL if the operation failed or if the value did not |
| 1489 | need to be actually stored within the array (as in the case of tied arrays). |
| 1490 | Otherwise it can be dereferenced to get the original C<SV*>. Note that the |
| 1491 | caller is responsible for suitably incrementing the reference count of C<val> |
| 1492 | before the call, and decrementing it if the function returned NULL. |
| 1493 | |
| 1494 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 1495 | information on how to use this function on tied arrays. |
| 1496 | |
| 1497 | SV** av_store _((AV* ar, I32 key, SV* val)); |
| 1498 | |
| 1499 | =item av_undef |
| 1500 | |
| 1501 | Undefines the array. Frees the memory used by the array itself. |
| 1502 | |
| 1503 | void av_undef _((AV* ar)); |
| 1504 | |
| 1505 | =item av_unshift |
| 1506 | |
| 1507 | Unshift the given number of C<undef> values onto the beginning of the |
| 1508 | array. The array will grow automatically to accommodate the addition. |
| 1509 | You must then use C<av_store> to assign values to these new elements. |
| 1510 | |
| 1511 | void av_unshift _((AV* ar, I32 num)); |
| 1512 | |
| 1513 | =item CLASS |
| 1514 | |
| 1515 | Variable which is setup by C<xsubpp> to indicate the class name for a C++ XS |
| 1516 | constructor. This is always a C<char*>. See C<THIS> and |
| 1517 | L<perlxs/"Using XS With C++">. |
| 1518 | |
| 1519 | =item Copy |
| 1520 | |
| 1521 | The XSUB-writer's interface to the C C<memcpy> function. The C<s> is the |
| 1522 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
| 1523 | the type. May fail on overlapping copies. See also C<Move>. |
| 1524 | |
| 1525 | (void) Copy( s, d, n, t ); |
| 1526 | |
| 1527 | =item croak |
| 1528 | |
| 1529 | This is the XSUB-writer's interface to Perl's C<die> function. Use this |
| 1530 | function the same way you use the C C<printf> function. See C<warn>. |
| 1531 | |
| 1532 | =item CvSTASH |
| 1533 | |
| 1534 | Returns the stash of the CV. |
| 1535 | |
| 1536 | HV * CvSTASH( SV* sv ) |
| 1537 | |
| 1538 | =item DBsingle |
| 1539 | |
| 1540 | When Perl is run in debugging mode, with the B<-d> switch, this SV is a |
| 1541 | boolean which indicates whether subs are being single-stepped. |
| 1542 | Single-stepping is automatically turned on after every step. This is the C |
| 1543 | variable which corresponds to Perl's $DB::single variable. See C<DBsub>. |
| 1544 | |
| 1545 | =item DBsub |
| 1546 | |
| 1547 | When Perl is run in debugging mode, with the B<-d> switch, this GV contains |
| 1548 | the SV which holds the name of the sub being debugged. This is the C |
| 1549 | variable which corresponds to Perl's $DB::sub variable. See C<DBsingle>. |
| 1550 | The sub name can be found by |
| 1551 | |
| 1552 | SvPV( GvSV( DBsub ), na ) |
| 1553 | |
| 1554 | =item DBtrace |
| 1555 | |
| 1556 | Trace variable used when Perl is run in debugging mode, with the B<-d> |
| 1557 | switch. This is the C variable which corresponds to Perl's $DB::trace |
| 1558 | variable. See C<DBsingle>. |
| 1559 | |
| 1560 | =item dMARK |
| 1561 | |
| 1562 | Declare a stack marker variable, C<mark>, for the XSUB. See C<MARK> and |
| 1563 | C<dORIGMARK>. |
| 1564 | |
| 1565 | =item dORIGMARK |
| 1566 | |
| 1567 | Saves the original stack mark for the XSUB. See C<ORIGMARK>. |
| 1568 | |
| 1569 | =item dowarn |
| 1570 | |
| 1571 | The C variable which corresponds to Perl's $^W warning variable. |
| 1572 | |
| 1573 | =item dSP |
| 1574 | |
| 1575 | Declares a stack pointer variable, C<sp>, for the XSUB. See C<SP>. |
| 1576 | |
| 1577 | =item dXSARGS |
| 1578 | |
| 1579 | Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is |
| 1580 | usually handled automatically by C<xsubpp>. Declares the C<items> variable |
| 1581 | to indicate the number of items on the stack. |
| 1582 | |
| 1583 | =item dXSI32 |
| 1584 | |
| 1585 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually |
| 1586 | handled automatically by C<xsubpp>. |
| 1587 | |
| 1588 | =item ENTER |
| 1589 | |
| 1590 | Opening bracket on a callback. See C<LEAVE> and L<perlcall>. |
| 1591 | |
| 1592 | ENTER; |
| 1593 | |
| 1594 | =item EXTEND |
| 1595 | |
| 1596 | Used to extend the argument stack for an XSUB's return values. |
| 1597 | |
| 1598 | EXTEND( sp, int x ); |
| 1599 | |
| 1600 | =item FREETMPS |
| 1601 | |
| 1602 | Closing bracket for temporaries on a callback. See C<SAVETMPS> and |
| 1603 | L<perlcall>. |
| 1604 | |
| 1605 | FREETMPS; |
| 1606 | |
| 1607 | =item G_ARRAY |
| 1608 | |
| 1609 | Used to indicate array context. See C<GIMME_V>, C<GIMME> and L<perlcall>. |
| 1610 | |
| 1611 | =item G_DISCARD |
| 1612 | |
| 1613 | Indicates that arguments returned from a callback should be discarded. See |
| 1614 | L<perlcall>. |
| 1615 | |
| 1616 | =item G_EVAL |
| 1617 | |
| 1618 | Used to force a Perl C<eval> wrapper around a callback. See L<perlcall>. |
| 1619 | |
| 1620 | =item GIMME |
| 1621 | |
| 1622 | A backward-compatible version of C<GIMME_V> which can only return |
| 1623 | C<G_SCALAR> or C<G_ARRAY>; in a void context, it returns C<G_SCALAR>. |
| 1624 | |
| 1625 | =item GIMME_V |
| 1626 | |
| 1627 | The XSUB-writer's equivalent to Perl's C<wantarray>. Returns |
| 1628 | C<G_VOID>, C<G_SCALAR> or C<G_ARRAY> for void, scalar or array |
| 1629 | context, respectively. |
| 1630 | |
| 1631 | =item G_NOARGS |
| 1632 | |
| 1633 | Indicates that no arguments are being sent to a callback. See L<perlcall>. |
| 1634 | |
| 1635 | =item G_SCALAR |
| 1636 | |
| 1637 | Used to indicate scalar context. See C<GIMME_V>, C<GIMME>, and L<perlcall>. |
| 1638 | |
| 1639 | =item G_VOID |
| 1640 | |
| 1641 | Used to indicate void context. See C<GIMME_V> and L<perlcall>. |
| 1642 | |
| 1643 | =item gv_fetchmeth |
| 1644 | |
| 1645 | Returns the glob with the given C<name> and a defined subroutine or |
| 1646 | C<NULL>. The glob lives in the given C<stash>, or in the stashes |
| 1647 | accessable via @ISA and @<UNIVERSAL>. |
| 1648 | |
| 1649 | The argument C<level> should be either 0 or -1. If C<level==0>, as a |
| 1650 | side-effect creates a glob with the given C<name> in the given |
| 1651 | C<stash> which in the case of success contains an alias for the |
| 1652 | subroutine, and sets up caching info for this glob. Similarly for all |
| 1653 | the searched stashes. |
| 1654 | |
| 1655 | This function grants C<"SUPER"> token as a postfix of the stash name. |
| 1656 | |
| 1657 | The GV returned from C<gv_fetchmeth> may be a method cache entry, |
| 1658 | which is not visible to Perl code. So when calling C<perl_call_sv>, |
| 1659 | you should not use the GV directly; instead, you should use the |
| 1660 | method's CV, which can be obtained from the GV with the C<GvCV> macro. |
| 1661 | |
| 1662 | GV* gv_fetchmeth _((HV* stash, char* name, STRLEN len, I32 level)); |
| 1663 | |
| 1664 | =item gv_fetchmethod |
| 1665 | |
| 1666 | =item gv_fetchmethod_autoload |
| 1667 | |
| 1668 | Returns the glob which contains the subroutine to call to invoke the |
| 1669 | method on the C<stash>. In fact in the presense of autoloading this may |
| 1670 | be the glob for "AUTOLOAD". In this case the corresponding variable |
| 1671 | $AUTOLOAD is already setup. |
| 1672 | |
| 1673 | The third parameter of C<gv_fetchmethod_autoload> determines whether AUTOLOAD |
| 1674 | lookup is performed if the given method is not present: non-zero means |
| 1675 | yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling |
| 1676 | C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload> with a |
| 1677 | non-zero C<autoload> parameter. |
| 1678 | |
| 1679 | These functions grant C<"SUPER"> token as a prefix of the method name. |
| 1680 | |
| 1681 | Note that if you want to keep the returned glob for a long time, you |
| 1682 | need to check for it being "AUTOLOAD", since at the later time the call |
| 1683 | may load a different subroutine due to $AUTOLOAD changing its value. |
| 1684 | Use the glob created via a side effect to do this. |
| 1685 | |
| 1686 | These functions have the same side-effects and as C<gv_fetchmeth> with |
| 1687 | C<level==0>. C<name> should be writable if contains C<':'> or C<'\''>. |
| 1688 | The warning against passing the GV returned by C<gv_fetchmeth> to |
| 1689 | C<perl_call_sv> apply equally to these functions. |
| 1690 | |
| 1691 | GV* gv_fetchmethod _((HV* stash, char* name)); |
| 1692 | GV* gv_fetchmethod_autoload _((HV* stash, char* name, |
| 1693 | I32 autoload)); |
| 1694 | |
| 1695 | =item gv_stashpv |
| 1696 | |
| 1697 | Returns a pointer to the stash for a specified package. If C<create> is set |
| 1698 | then the package will be created if it does not already exist. If C<create> |
| 1699 | is not set and the package does not exist then NULL is returned. |
| 1700 | |
| 1701 | HV* gv_stashpv _((char* name, I32 create)); |
| 1702 | |
| 1703 | =item gv_stashsv |
| 1704 | |
| 1705 | Returns a pointer to the stash for a specified package. See C<gv_stashpv>. |
| 1706 | |
| 1707 | HV* gv_stashsv _((SV* sv, I32 create)); |
| 1708 | |
| 1709 | =item GvSV |
| 1710 | |
| 1711 | Return the SV from the GV. |
| 1712 | |
| 1713 | =item HEf_SVKEY |
| 1714 | |
| 1715 | This flag, used in the length slot of hash entries and magic |
| 1716 | structures, specifies the structure contains a C<SV*> pointer where a |
| 1717 | C<char*> pointer is to be expected. (For information only--not to be used). |
| 1718 | |
| 1719 | =item HeHASH |
| 1720 | |
| 1721 | Returns the computed hash (type C<U32>) stored in the hash entry. |
| 1722 | |
| 1723 | HeHASH(HE* he) |
| 1724 | |
| 1725 | =item HeKEY |
| 1726 | |
| 1727 | Returns the actual pointer stored in the key slot of the hash entry. |
| 1728 | The pointer may be either C<char*> or C<SV*>, depending on the value of |
| 1729 | C<HeKLEN()>. Can be assigned to. The C<HePV()> or C<HeSVKEY()> macros |
| 1730 | are usually preferable for finding the value of a key. |
| 1731 | |
| 1732 | HeKEY(HE* he) |
| 1733 | |
| 1734 | =item HeKLEN |
| 1735 | |
| 1736 | If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry |
| 1737 | holds an C<SV*> key. Otherwise, holds the actual length of the key. |
| 1738 | Can be assigned to. The C<HePV()> macro is usually preferable for finding |
| 1739 | key lengths. |
| 1740 | |
| 1741 | HeKLEN(HE* he) |
| 1742 | |
| 1743 | =item HePV |
| 1744 | |
| 1745 | Returns the key slot of the hash entry as a C<char*> value, doing any |
| 1746 | necessary dereferencing of possibly C<SV*> keys. The length of |
| 1747 | the string is placed in C<len> (this is a macro, so do I<not> use |
| 1748 | C<&len>). If you do not care about what the length of the key is, |
| 1749 | you may use the global variable C<na>. Remember though, that hash |
| 1750 | keys in perl are free to contain embedded nulls, so using C<strlen()> |
| 1751 | or similar is not a good way to find the length of hash keys. |
| 1752 | This is very similar to the C<SvPV()> macro described elsewhere in |
| 1753 | this document. |
| 1754 | |
| 1755 | HePV(HE* he, STRLEN len) |
| 1756 | |
| 1757 | =item HeSVKEY |
| 1758 | |
| 1759 | Returns the key as an C<SV*>, or C<Nullsv> if the hash entry |
| 1760 | does not contain an C<SV*> key. |
| 1761 | |
| 1762 | HeSVKEY(HE* he) |
| 1763 | |
| 1764 | =item HeSVKEY_force |
| 1765 | |
| 1766 | Returns the key as an C<SV*>. Will create and return a temporary |
| 1767 | mortal C<SV*> if the hash entry contains only a C<char*> key. |
| 1768 | |
| 1769 | HeSVKEY_force(HE* he) |
| 1770 | |
| 1771 | =item HeSVKEY_set |
| 1772 | |
| 1773 | Sets the key to a given C<SV*>, taking care to set the appropriate flags |
| 1774 | to indicate the presence of an C<SV*> key, and returns the same C<SV*>. |
| 1775 | |
| 1776 | HeSVKEY_set(HE* he, SV* sv) |
| 1777 | |
| 1778 | =item HeVAL |
| 1779 | |
| 1780 | Returns the value slot (type C<SV*>) stored in the hash entry. |
| 1781 | |
| 1782 | HeVAL(HE* he) |
| 1783 | |
| 1784 | =item hv_clear |
| 1785 | |
| 1786 | Clears a hash, making it empty. |
| 1787 | |
| 1788 | void hv_clear _((HV* tb)); |
| 1789 | |
| 1790 | =item hv_delayfree_ent |
| 1791 | |
| 1792 | Releases a hash entry, such as while iterating though the hash, but |
| 1793 | delays actual freeing of key and value until the end of the current |
| 1794 | statement (or thereabouts) with C<sv_2mortal>. See C<hv_iternext> |
| 1795 | and C<hv_free_ent>. |
| 1796 | |
| 1797 | void hv_delayfree_ent _((HV* hv, HE* entry)); |
| 1798 | |
| 1799 | =item hv_delete |
| 1800 | |
| 1801 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
| 1802 | and returned to the caller. The C<klen> is the length of the key. The |
| 1803 | C<flags> value will normally be zero; if set to G_DISCARD then NULL will be |
| 1804 | returned. |
| 1805 | |
| 1806 | SV* hv_delete _((HV* tb, char* key, U32 klen, I32 flags)); |
| 1807 | |
| 1808 | =item hv_delete_ent |
| 1809 | |
| 1810 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
| 1811 | and returned to the caller. The C<flags> value will normally be zero; if set |
| 1812 | to G_DISCARD then NULL will be returned. C<hash> can be a valid precomputed |
| 1813 | hash value, or 0 to ask for it to be computed. |
| 1814 | |
| 1815 | SV* hv_delete_ent _((HV* tb, SV* key, I32 flags, U32 hash)); |
| 1816 | |
| 1817 | =item hv_exists |
| 1818 | |
| 1819 | Returns a boolean indicating whether the specified hash key exists. The |
| 1820 | C<klen> is the length of the key. |
| 1821 | |
| 1822 | bool hv_exists _((HV* tb, char* key, U32 klen)); |
| 1823 | |
| 1824 | =item hv_exists_ent |
| 1825 | |
| 1826 | Returns a boolean indicating whether the specified hash key exists. C<hash> |
| 1827 | can be a valid precomputed hash value, or 0 to ask for it to be computed. |
| 1828 | |
| 1829 | bool hv_exists_ent _((HV* tb, SV* key, U32 hash)); |
| 1830 | |
| 1831 | =item hv_fetch |
| 1832 | |
| 1833 | Returns the SV which corresponds to the specified key in the hash. The |
| 1834 | C<klen> is the length of the key. If C<lval> is set then the fetch will be |
| 1835 | part of a store. Check that the return value is non-null before |
| 1836 | dereferencing it to a C<SV*>. |
| 1837 | |
| 1838 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 1839 | information on how to use this function on tied hashes. |
| 1840 | |
| 1841 | SV** hv_fetch _((HV* tb, char* key, U32 klen, I32 lval)); |
| 1842 | |
| 1843 | =item hv_fetch_ent |
| 1844 | |
| 1845 | Returns the hash entry which corresponds to the specified key in the hash. |
| 1846 | C<hash> must be a valid precomputed hash number for the given C<key>, or |
| 1847 | 0 if you want the function to compute it. IF C<lval> is set then the |
| 1848 | fetch will be part of a store. Make sure the return value is non-null |
| 1849 | before accessing it. The return value when C<tb> is a tied hash |
| 1850 | is a pointer to a static location, so be sure to make a copy of the |
| 1851 | structure if you need to store it somewhere. |
| 1852 | |
| 1853 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 1854 | information on how to use this function on tied hashes. |
| 1855 | |
| 1856 | HE* hv_fetch_ent _((HV* tb, SV* key, I32 lval, U32 hash)); |
| 1857 | |
| 1858 | =item hv_free_ent |
| 1859 | |
| 1860 | Releases a hash entry, such as while iterating though the hash. See |
| 1861 | C<hv_iternext> and C<hv_delayfree_ent>. |
| 1862 | |
| 1863 | void hv_free_ent _((HV* hv, HE* entry)); |
| 1864 | |
| 1865 | =item hv_iterinit |
| 1866 | |
| 1867 | Prepares a starting point to traverse a hash table. |
| 1868 | |
| 1869 | I32 hv_iterinit _((HV* tb)); |
| 1870 | |
| 1871 | Note that hv_iterinit I<currently> returns the number of I<buckets> in |
| 1872 | the hash and I<not> the number of keys (as indicated in the Advanced |
| 1873 | Perl Programming book). This may change in future. Use the HvKEYS(hv) |
| 1874 | macro to find the number of keys in a hash. |
| 1875 | |
| 1876 | =item hv_iterkey |
| 1877 | |
| 1878 | Returns the key from the current position of the hash iterator. See |
| 1879 | C<hv_iterinit>. |
| 1880 | |
| 1881 | char* hv_iterkey _((HE* entry, I32* retlen)); |
| 1882 | |
| 1883 | =item hv_iterkeysv |
| 1884 | |
| 1885 | Returns the key as an C<SV*> from the current position of the hash |
| 1886 | iterator. The return value will always be a mortal copy of the |
| 1887 | key. Also see C<hv_iterinit>. |
| 1888 | |
| 1889 | SV* hv_iterkeysv _((HE* entry)); |
| 1890 | |
| 1891 | =item hv_iternext |
| 1892 | |
| 1893 | Returns entries from a hash iterator. See C<hv_iterinit>. |
| 1894 | |
| 1895 | HE* hv_iternext _((HV* tb)); |
| 1896 | |
| 1897 | =item hv_iternextsv |
| 1898 | |
| 1899 | Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one |
| 1900 | operation. |
| 1901 | |
| 1902 | SV * hv_iternextsv _((HV* hv, char** key, I32* retlen)); |
| 1903 | |
| 1904 | =item hv_iterval |
| 1905 | |
| 1906 | Returns the value from the current position of the hash iterator. See |
| 1907 | C<hv_iterkey>. |
| 1908 | |
| 1909 | SV* hv_iterval _((HV* tb, HE* entry)); |
| 1910 | |
| 1911 | =item hv_magic |
| 1912 | |
| 1913 | Adds magic to a hash. See C<sv_magic>. |
| 1914 | |
| 1915 | void hv_magic _((HV* hv, GV* gv, int how)); |
| 1916 | |
| 1917 | =item HvNAME |
| 1918 | |
| 1919 | Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>. |
| 1920 | |
| 1921 | char *HvNAME (HV* stash) |
| 1922 | |
| 1923 | =item hv_store |
| 1924 | |
| 1925 | Stores an SV in a hash. The hash key is specified as C<key> and C<klen> is |
| 1926 | the length of the key. The C<hash> parameter is the precomputed hash |
| 1927 | value; if it is zero then Perl will compute it. The return value will be |
| 1928 | NULL if the operation failed or if the value did not need to be actually |
| 1929 | stored within the hash (as in the case of tied hashes). Otherwise it can |
| 1930 | be dereferenced to get the original C<SV*>. Note that the caller is |
| 1931 | responsible for suitably incrementing the reference count of C<val> |
| 1932 | before the call, and decrementing it if the function returned NULL. |
| 1933 | |
| 1934 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 1935 | information on how to use this function on tied hashes. |
| 1936 | |
| 1937 | SV** hv_store _((HV* tb, char* key, U32 klen, SV* val, U32 hash)); |
| 1938 | |
| 1939 | =item hv_store_ent |
| 1940 | |
| 1941 | Stores C<val> in a hash. The hash key is specified as C<key>. The C<hash> |
| 1942 | parameter is the precomputed hash value; if it is zero then Perl will |
| 1943 | compute it. The return value is the new hash entry so created. It will be |
| 1944 | NULL if the operation failed or if the value did not need to be actually |
| 1945 | stored within the hash (as in the case of tied hashes). Otherwise the |
| 1946 | contents of the return value can be accessed using the C<He???> macros |
| 1947 | described here. Note that the caller is responsible for suitably |
| 1948 | incrementing the reference count of C<val> before the call, and decrementing |
| 1949 | it if the function returned NULL. |
| 1950 | |
| 1951 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
| 1952 | information on how to use this function on tied hashes. |
| 1953 | |
| 1954 | HE* hv_store_ent _((HV* tb, SV* key, SV* val, U32 hash)); |
| 1955 | |
| 1956 | =item hv_undef |
| 1957 | |
| 1958 | Undefines the hash. |
| 1959 | |
| 1960 | void hv_undef _((HV* tb)); |
| 1961 | |
| 1962 | =item isALNUM |
| 1963 | |
| 1964 | Returns a boolean indicating whether the C C<char> is an ascii alphanumeric |
| 1965 | character or digit. |
| 1966 | |
| 1967 | int isALNUM (char c) |
| 1968 | |
| 1969 | =item isALPHA |
| 1970 | |
| 1971 | Returns a boolean indicating whether the C C<char> is an ascii alphabetic |
| 1972 | character. |
| 1973 | |
| 1974 | int isALPHA (char c) |
| 1975 | |
| 1976 | =item isDIGIT |
| 1977 | |
| 1978 | Returns a boolean indicating whether the C C<char> is an ascii digit. |
| 1979 | |
| 1980 | int isDIGIT (char c) |
| 1981 | |
| 1982 | =item isLOWER |
| 1983 | |
| 1984 | Returns a boolean indicating whether the C C<char> is a lowercase character. |
| 1985 | |
| 1986 | int isLOWER (char c) |
| 1987 | |
| 1988 | =item isSPACE |
| 1989 | |
| 1990 | Returns a boolean indicating whether the C C<char> is whitespace. |
| 1991 | |
| 1992 | int isSPACE (char c) |
| 1993 | |
| 1994 | =item isUPPER |
| 1995 | |
| 1996 | Returns a boolean indicating whether the C C<char> is an uppercase character. |
| 1997 | |
| 1998 | int isUPPER (char c) |
| 1999 | |
| 2000 | =item items |
| 2001 | |
| 2002 | Variable which is setup by C<xsubpp> to indicate the number of items on the |
| 2003 | stack. See L<perlxs/"Variable-length Parameter Lists">. |
| 2004 | |
| 2005 | =item ix |
| 2006 | |
| 2007 | Variable which is setup by C<xsubpp> to indicate which of an XSUB's aliases |
| 2008 | was used to invoke it. See L<perlxs/"The ALIAS: Keyword">. |
| 2009 | |
| 2010 | =item LEAVE |
| 2011 | |
| 2012 | Closing bracket on a callback. See C<ENTER> and L<perlcall>. |
| 2013 | |
| 2014 | LEAVE; |
| 2015 | |
| 2016 | =item MARK |
| 2017 | |
| 2018 | Stack marker variable for the XSUB. See C<dMARK>. |
| 2019 | |
| 2020 | =item mg_clear |
| 2021 | |
| 2022 | Clear something magical that the SV represents. See C<sv_magic>. |
| 2023 | |
| 2024 | int mg_clear _((SV* sv)); |
| 2025 | |
| 2026 | =item mg_copy |
| 2027 | |
| 2028 | Copies the magic from one SV to another. See C<sv_magic>. |
| 2029 | |
| 2030 | int mg_copy _((SV *, SV *, char *, STRLEN)); |
| 2031 | |
| 2032 | =item mg_find |
| 2033 | |
| 2034 | Finds the magic pointer for type matching the SV. See C<sv_magic>. |
| 2035 | |
| 2036 | MAGIC* mg_find _((SV* sv, int type)); |
| 2037 | |
| 2038 | =item mg_free |
| 2039 | |
| 2040 | Free any magic storage used by the SV. See C<sv_magic>. |
| 2041 | |
| 2042 | int mg_free _((SV* sv)); |
| 2043 | |
| 2044 | =item mg_get |
| 2045 | |
| 2046 | Do magic after a value is retrieved from the SV. See C<sv_magic>. |
| 2047 | |
| 2048 | int mg_get _((SV* sv)); |
| 2049 | |
| 2050 | =item mg_len |
| 2051 | |
| 2052 | Report on the SV's length. See C<sv_magic>. |
| 2053 | |
| 2054 | U32 mg_len _((SV* sv)); |
| 2055 | |
| 2056 | =item mg_magical |
| 2057 | |
| 2058 | Turns on the magical status of an SV. See C<sv_magic>. |
| 2059 | |
| 2060 | void mg_magical _((SV* sv)); |
| 2061 | |
| 2062 | =item mg_set |
| 2063 | |
| 2064 | Do magic after a value is assigned to the SV. See C<sv_magic>. |
| 2065 | |
| 2066 | int mg_set _((SV* sv)); |
| 2067 | |
| 2068 | =item Move |
| 2069 | |
| 2070 | The XSUB-writer's interface to the C C<memmove> function. The C<s> is the |
| 2071 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
| 2072 | the type. Can do overlapping moves. See also C<Copy>. |
| 2073 | |
| 2074 | (void) Move( s, d, n, t ); |
| 2075 | |
| 2076 | =item na |
| 2077 | |
| 2078 | A variable which may be used with C<SvPV> to tell Perl to calculate the |
| 2079 | string length. |
| 2080 | |
| 2081 | =item New |
| 2082 | |
| 2083 | The XSUB-writer's interface to the C C<malloc> function. |
| 2084 | |
| 2085 | void * New( x, void *ptr, int size, type ) |
| 2086 | |
| 2087 | =item Newc |
| 2088 | |
| 2089 | The XSUB-writer's interface to the C C<malloc> function, with cast. |
| 2090 | |
| 2091 | void * Newc( x, void *ptr, int size, type, cast ) |
| 2092 | |
| 2093 | =item Newz |
| 2094 | |
| 2095 | The XSUB-writer's interface to the C C<malloc> function. The allocated |
| 2096 | memory is zeroed with C<memzero>. |
| 2097 | |
| 2098 | void * Newz( x, void *ptr, int size, type ) |
| 2099 | |
| 2100 | =item newAV |
| 2101 | |
| 2102 | Creates a new AV. The reference count is set to 1. |
| 2103 | |
| 2104 | AV* newAV _((void)); |
| 2105 | |
| 2106 | =item newHV |
| 2107 | |
| 2108 | Creates a new HV. The reference count is set to 1. |
| 2109 | |
| 2110 | HV* newHV _((void)); |
| 2111 | |
| 2112 | =item newRV_inc |
| 2113 | |
| 2114 | Creates an RV wrapper for an SV. The reference count for the original SV is |
| 2115 | incremented. |
| 2116 | |
| 2117 | SV* newRV_inc _((SV* ref)); |
| 2118 | |
| 2119 | For historical reasons, "newRV" is a synonym for "newRV_inc". |
| 2120 | |
| 2121 | =item newRV_noinc |
| 2122 | |
| 2123 | Creates an RV wrapper for an SV. The reference count for the original |
| 2124 | SV is B<not> incremented. |
| 2125 | |
| 2126 | SV* newRV_noinc _((SV* ref)); |
| 2127 | |
| 2128 | =item NEWSV |
| 2129 | |
| 2130 | Creates a new SV. The C<len> parameter indicates the number of bytes of |
| 2131 | preallocated string space the SV should have. The reference count for the |
| 2132 | new SV is set to 1. C<id> is an integer id between 0 and 1299 (used to |
| 2133 | identify leaks). |
| 2134 | |
| 2135 | SV* NEWSV _((int id, STRLEN len)); |
| 2136 | |
| 2137 | =item newSViv |
| 2138 | |
| 2139 | Creates a new SV and copies an integer into it. The reference count for the |
| 2140 | SV is set to 1. |
| 2141 | |
| 2142 | SV* newSViv _((IV i)); |
| 2143 | |
| 2144 | =item newSVnv |
| 2145 | |
| 2146 | Creates a new SV and copies a double into it. The reference count for the |
| 2147 | SV is set to 1. |
| 2148 | |
| 2149 | SV* newSVnv _((NV i)); |
| 2150 | |
| 2151 | =item newSVpv |
| 2152 | |
| 2153 | Creates a new SV and copies a string into it. The reference count for the |
| 2154 | SV is set to 1. If C<len> is zero then Perl will compute the length. |
| 2155 | |
| 2156 | SV* newSVpv _((char* s, STRLEN len)); |
| 2157 | |
| 2158 | =item newSVpvn |
| 2159 | |
| 2160 | Creates a new SV and copies a string into it. The reference count for the |
| 2161 | SV is set to 1. If C<len> is zero then Perl will create a zero length |
| 2162 | string. |
| 2163 | |
| 2164 | SV* newSVpvn _((char* s, STRLEN len)); |
| 2165 | |
| 2166 | =item newSVrv |
| 2167 | |
| 2168 | Creates a new SV for the RV, C<rv>, to point to. If C<rv> is not an RV then |
| 2169 | it will be upgraded to one. If C<classname> is non-null then the new SV will |
| 2170 | be blessed in the specified package. The new SV is returned and its |
| 2171 | reference count is 1. |
| 2172 | |
| 2173 | SV* newSVrv _((SV* rv, char* classname)); |
| 2174 | |
| 2175 | =item newSVsv |
| 2176 | |
| 2177 | Creates a new SV which is an exact duplicate of the original SV. |
| 2178 | |
| 2179 | SV* newSVsv _((SV* old)); |
| 2180 | |
| 2181 | =item newXS |
| 2182 | |
| 2183 | Used by C<xsubpp> to hook up XSUBs as Perl subs. |
| 2184 | |
| 2185 | =item newXSproto |
| 2186 | |
| 2187 | Used by C<xsubpp> to hook up XSUBs as Perl subs. Adds Perl prototypes to |
| 2188 | the subs. |
| 2189 | |
| 2190 | =item Nullav |
| 2191 | |
| 2192 | Null AV pointer. |
| 2193 | |
| 2194 | =item Nullch |
| 2195 | |
| 2196 | Null character pointer. |
| 2197 | |
| 2198 | =item Nullcv |
| 2199 | |
| 2200 | Null CV pointer. |
| 2201 | |
| 2202 | =item Nullhv |
| 2203 | |
| 2204 | Null HV pointer. |
| 2205 | |
| 2206 | =item Nullsv |
| 2207 | |
| 2208 | Null SV pointer. |
| 2209 | |
| 2210 | =item ORIGMARK |
| 2211 | |
| 2212 | The original stack mark for the XSUB. See C<dORIGMARK>. |
| 2213 | |
| 2214 | =item perl_alloc |
| 2215 | |
| 2216 | Allocates a new Perl interpreter. See L<perlembed>. |
| 2217 | |
| 2218 | =item perl_call_argv |
| 2219 | |
| 2220 | Performs a callback to the specified Perl sub. See L<perlcall>. |
| 2221 | |
| 2222 | I32 perl_call_argv _((char* subname, I32 flags, char** argv)); |
| 2223 | |
| 2224 | =item perl_call_method |
| 2225 | |
| 2226 | Performs a callback to the specified Perl method. The blessed object must |
| 2227 | be on the stack. See L<perlcall>. |
| 2228 | |
| 2229 | I32 perl_call_method _((char* methname, I32 flags)); |
| 2230 | |
| 2231 | =item perl_call_pv |
| 2232 | |
| 2233 | Performs a callback to the specified Perl sub. See L<perlcall>. |
| 2234 | |
| 2235 | I32 perl_call_pv _((char* subname, I32 flags)); |
| 2236 | |
| 2237 | =item perl_call_sv |
| 2238 | |
| 2239 | Performs a callback to the Perl sub whose name is in the SV. See |
| 2240 | L<perlcall>. |
| 2241 | |
| 2242 | I32 perl_call_sv _((SV* sv, I32 flags)); |
| 2243 | |
| 2244 | =item perl_construct |
| 2245 | |
| 2246 | Initializes a new Perl interpreter. See L<perlembed>. |
| 2247 | |
| 2248 | =item perl_destruct |
| 2249 | |
| 2250 | Shuts down a Perl interpreter. See L<perlembed>. |
| 2251 | |
| 2252 | =item perl_eval_sv |
| 2253 | |
| 2254 | Tells Perl to C<eval> the string in the SV. |
| 2255 | |
| 2256 | I32 perl_eval_sv _((SV* sv, I32 flags)); |
| 2257 | |
| 2258 | =item perl_eval_pv |
| 2259 | |
| 2260 | Tells Perl to C<eval> the given string and return an SV* result. |
| 2261 | |
| 2262 | SV* perl_eval_pv _((char* p, I32 croak_on_error)); |
| 2263 | |
| 2264 | =item perl_free |
| 2265 | |
| 2266 | Releases a Perl interpreter. See L<perlembed>. |
| 2267 | |
| 2268 | =item perl_get_av |
| 2269 | |
| 2270 | Returns the AV of the specified Perl array. If C<create> is set and the |
| 2271 | Perl variable does not exist then it will be created. If C<create> is not |
| 2272 | set and the variable does not exist then NULL is returned. |
| 2273 | |
| 2274 | AV* perl_get_av _((char* name, I32 create)); |
| 2275 | |
| 2276 | =item perl_get_cv |
| 2277 | |
| 2278 | Returns the CV of the specified Perl sub. If C<create> is set and the Perl |
| 2279 | variable does not exist then it will be created. If C<create> is not |
| 2280 | set and the variable does not exist then NULL is returned. |
| 2281 | |
| 2282 | CV* perl_get_cv _((char* name, I32 create)); |
| 2283 | |
| 2284 | =item perl_get_hv |
| 2285 | |
| 2286 | Returns the HV of the specified Perl hash. If C<create> is set and the Perl |
| 2287 | variable does not exist then it will be created. If C<create> is not |
| 2288 | set and the variable does not exist then NULL is returned. |
| 2289 | |
| 2290 | HV* perl_get_hv _((char* name, I32 create)); |
| 2291 | |
| 2292 | =item perl_get_sv |
| 2293 | |
| 2294 | Returns the SV of the specified Perl scalar. If C<create> is set and the |
| 2295 | Perl variable does not exist then it will be created. If C<create> is not |
| 2296 | set and the variable does not exist then NULL is returned. |
| 2297 | |
| 2298 | SV* perl_get_sv _((char* name, I32 create)); |
| 2299 | |
| 2300 | =item perl_parse |
| 2301 | |
| 2302 | Tells a Perl interpreter to parse a Perl script. See L<perlembed>. |
| 2303 | |
| 2304 | =item perl_require_pv |
| 2305 | |
| 2306 | Tells Perl to C<require> a module. |
| 2307 | |
| 2308 | void perl_require_pv _((char* pv)); |
| 2309 | |
| 2310 | =item perl_run |
| 2311 | |
| 2312 | Tells a Perl interpreter to run. See L<perlembed>. |
| 2313 | |
| 2314 | =item POPi |
| 2315 | |
| 2316 | Pops an integer off the stack. |
| 2317 | |
| 2318 | int POPi(); |
| 2319 | |
| 2320 | =item POPl |
| 2321 | |
| 2322 | Pops a long off the stack. |
| 2323 | |
| 2324 | long POPl(); |
| 2325 | |
| 2326 | =item POPp |
| 2327 | |
| 2328 | Pops a string off the stack. |
| 2329 | |
| 2330 | char * POPp(); |
| 2331 | |
| 2332 | =item POPn |
| 2333 | |
| 2334 | Pops a double off the stack. |
| 2335 | |
| 2336 | double POPn(); |
| 2337 | |
| 2338 | =item POPs |
| 2339 | |
| 2340 | Pops an SV off the stack. |
| 2341 | |
| 2342 | SV* POPs(); |
| 2343 | |
| 2344 | =item PUSHMARK |
| 2345 | |
| 2346 | Opening bracket for arguments on a callback. See C<PUTBACK> and L<perlcall>. |
| 2347 | |
| 2348 | PUSHMARK(p) |
| 2349 | |
| 2350 | =item PUSHi |
| 2351 | |
| 2352 | Push an integer onto the stack. The stack must have room for this element. |
| 2353 | Handles 'set' magic. See C<XPUSHi>. |
| 2354 | |
| 2355 | PUSHi(int d) |
| 2356 | |
| 2357 | =item PUSHn |
| 2358 | |
| 2359 | Push a double onto the stack. The stack must have room for this element. |
| 2360 | Handles 'set' magic. See C<XPUSHn>. |
| 2361 | |
| 2362 | PUSHn(double d) |
| 2363 | |
| 2364 | =item PUSHp |
| 2365 | |
| 2366 | Push a string onto the stack. The stack must have room for this element. |
| 2367 | The C<len> indicates the length of the string. Handles 'set' magic. See |
| 2368 | C<XPUSHp>. |
| 2369 | |
| 2370 | PUSHp(char *c, int len ) |
| 2371 | |
| 2372 | =item PUSHs |
| 2373 | |
| 2374 | Push an SV onto the stack. The stack must have room for this element. Does |
| 2375 | not handle 'set' magic. See C<XPUSHs>. |
| 2376 | |
| 2377 | PUSHs(sv) |
| 2378 | |
| 2379 | =item PUTBACK |
| 2380 | |
| 2381 | Closing bracket for XSUB arguments. This is usually handled by C<xsubpp>. |
| 2382 | See C<PUSHMARK> and L<perlcall> for other uses. |
| 2383 | |
| 2384 | PUTBACK; |
| 2385 | |
| 2386 | =item Renew |
| 2387 | |
| 2388 | The XSUB-writer's interface to the C C<realloc> function. |
| 2389 | |
| 2390 | void * Renew( void *ptr, int size, type ) |
| 2391 | |
| 2392 | =item Renewc |
| 2393 | |
| 2394 | The XSUB-writer's interface to the C C<realloc> function, with cast. |
| 2395 | |
| 2396 | void * Renewc( void *ptr, int size, type, cast ) |
| 2397 | |
| 2398 | =item RETVAL |
| 2399 | |
| 2400 | Variable which is setup by C<xsubpp> to hold the return value for an XSUB. |
| 2401 | This is always the proper type for the XSUB. |
| 2402 | See L<perlxs/"The RETVAL Variable">. |
| 2403 | |
| 2404 | =item safefree |
| 2405 | |
| 2406 | The XSUB-writer's interface to the C C<free> function. |
| 2407 | |
| 2408 | =item safemalloc |
| 2409 | |
| 2410 | The XSUB-writer's interface to the C C<malloc> function. |
| 2411 | |
| 2412 | =item saferealloc |
| 2413 | |
| 2414 | The XSUB-writer's interface to the C C<realloc> function. |
| 2415 | |
| 2416 | =item savepv |
| 2417 | |
| 2418 | Copy a string to a safe spot. This does not use an SV. |
| 2419 | |
| 2420 | char* savepv _((char* sv)); |
| 2421 | |
| 2422 | =item savepvn |
| 2423 | |
| 2424 | Copy a string to a safe spot. The C<len> indicates number of bytes to |
| 2425 | copy. This does not use an SV. |
| 2426 | |
| 2427 | char* savepvn _((char* sv, I32 len)); |
| 2428 | |
| 2429 | =item SAVETMPS |
| 2430 | |
| 2431 | Opening bracket for temporaries on a callback. See C<FREETMPS> and |
| 2432 | L<perlcall>. |
| 2433 | |
| 2434 | SAVETMPS; |
| 2435 | |
| 2436 | =item SP |
| 2437 | |
| 2438 | Stack pointer. This is usually handled by C<xsubpp>. See C<dSP> and |
| 2439 | C<SPAGAIN>. |
| 2440 | |
| 2441 | =item SPAGAIN |
| 2442 | |
| 2443 | Refetch the stack pointer. Used after a callback. See L<perlcall>. |
| 2444 | |
| 2445 | SPAGAIN; |
| 2446 | |
| 2447 | =item ST |
| 2448 | |
| 2449 | Used to access elements on the XSUB's stack. |
| 2450 | |
| 2451 | SV* ST(int x) |
| 2452 | |
| 2453 | =item strEQ |
| 2454 | |
| 2455 | Test two strings to see if they are equal. Returns true or false. |
| 2456 | |
| 2457 | int strEQ( char *s1, char *s2 ) |
| 2458 | |
| 2459 | =item strGE |
| 2460 | |
| 2461 | Test two strings to see if the first, C<s1>, is greater than or equal to the |
| 2462 | second, C<s2>. Returns true or false. |
| 2463 | |
| 2464 | int strGE( char *s1, char *s2 ) |
| 2465 | |
| 2466 | =item strGT |
| 2467 | |
| 2468 | Test two strings to see if the first, C<s1>, is greater than the second, |
| 2469 | C<s2>. Returns true or false. |
| 2470 | |
| 2471 | int strGT( char *s1, char *s2 ) |
| 2472 | |
| 2473 | =item strLE |
| 2474 | |
| 2475 | Test two strings to see if the first, C<s1>, is less than or equal to the |
| 2476 | second, C<s2>. Returns true or false. |
| 2477 | |
| 2478 | int strLE( char *s1, char *s2 ) |
| 2479 | |
| 2480 | =item strLT |
| 2481 | |
| 2482 | Test two strings to see if the first, C<s1>, is less than the second, |
| 2483 | C<s2>. Returns true or false. |
| 2484 | |
| 2485 | int strLT( char *s1, char *s2 ) |
| 2486 | |
| 2487 | =item strNE |
| 2488 | |
| 2489 | Test two strings to see if they are different. Returns true or false. |
| 2490 | |
| 2491 | int strNE( char *s1, char *s2 ) |
| 2492 | |
| 2493 | =item strnEQ |
| 2494 | |
| 2495 | Test two strings to see if they are equal. The C<len> parameter indicates |
| 2496 | the number of bytes to compare. Returns true or false. |
| 2497 | |
| 2498 | int strnEQ( char *s1, char *s2 ) |
| 2499 | |
| 2500 | =item strnNE |
| 2501 | |
| 2502 | Test two strings to see if they are different. The C<len> parameter |
| 2503 | indicates the number of bytes to compare. Returns true or false. |
| 2504 | |
| 2505 | int strnNE( char *s1, char *s2, int len ) |
| 2506 | |
| 2507 | =item sv_2mortal |
| 2508 | |
| 2509 | Marks an SV as mortal. The SV will be destroyed when the current context |
| 2510 | ends. |
| 2511 | |
| 2512 | SV* sv_2mortal _((SV* sv)); |
| 2513 | |
| 2514 | =item sv_bless |
| 2515 | |
| 2516 | Blesses an SV into a specified package. The SV must be an RV. The package |
| 2517 | must be designated by its stash (see C<gv_stashpv()>). The reference count |
| 2518 | of the SV is unaffected. |
| 2519 | |
| 2520 | SV* sv_bless _((SV* sv, HV* stash)); |
| 2521 | |
| 2522 | =item SvCatMagicPV |
| 2523 | |
| 2524 | =item SvCatMagicPVN |
| 2525 | |
| 2526 | =item SvCatMagicSV |
| 2527 | |
| 2528 | =item sv_catpv |
| 2529 | |
| 2530 | Concatenates the string onto the end of the string which is in the SV. |
| 2531 | Handles 'get' magic, but not 'set' magic. See C<SvCatMagicPV>. |
| 2532 | |
| 2533 | void sv_catpv _((SV* sv, char* ptr)); |
| 2534 | |
| 2535 | =item sv_catpvn |
| 2536 | |
| 2537 | Concatenates the string onto the end of the string which is in the SV. The |
| 2538 | C<len> indicates number of bytes to copy. Handles 'get' magic, but not |
| 2539 | 'set' magic. See C<SvCatMagicPVN). |
| 2540 | |
| 2541 | void sv_catpvn _((SV* sv, char* ptr, STRLEN len)); |
| 2542 | |
| 2543 | =item sv_catpvf |
| 2544 | |
| 2545 | Processes its arguments like C<sprintf> and appends the formatted output |
| 2546 | to an SV. Handles 'get' magic, but not 'set' magic. C<SvSETMAGIC()> must |
| 2547 | typically be called after calling this function to handle 'set' magic. |
| 2548 | |
| 2549 | void sv_catpvf _((SV* sv, const char* pat, ...)); |
| 2550 | |
| 2551 | =item sv_catsv |
| 2552 | |
| 2553 | Concatenates the string from SV C<ssv> onto the end of the string in SV |
| 2554 | C<dsv>. Handles 'get' magic, but not 'set' magic. See C<SvCatMagicSV). |
| 2555 | |
| 2556 | void sv_catsv _((SV* dsv, SV* ssv)); |
| 2557 | |
| 2558 | =item sv_cmp |
| 2559 | |
| 2560 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the |
| 2561 | string in C<sv1> is less than, equal to, or greater than the string in |
| 2562 | C<sv2>. |
| 2563 | |
| 2564 | I32 sv_cmp _((SV* sv1, SV* sv2)); |
| 2565 | |
| 2566 | =item SvCUR |
| 2567 | |
| 2568 | Returns the length of the string which is in the SV. See C<SvLEN>. |
| 2569 | |
| 2570 | int SvCUR (SV* sv) |
| 2571 | |
| 2572 | =item SvCUR_set |
| 2573 | |
| 2574 | Set the length of the string which is in the SV. See C<SvCUR>. |
| 2575 | |
| 2576 | SvCUR_set (SV* sv, int val ) |
| 2577 | |
| 2578 | =item sv_dec |
| 2579 | |
| 2580 | Auto-decrement of the value in the SV. |
| 2581 | |
| 2582 | void sv_dec _((SV* sv)); |
| 2583 | |
| 2584 | =item SvEND |
| 2585 | |
| 2586 | Returns a pointer to the last character in the string which is in the SV. |
| 2587 | See C<SvCUR>. Access the character as |
| 2588 | |
| 2589 | *SvEND(sv) |
| 2590 | |
| 2591 | =item sv_eq |
| 2592 | |
| 2593 | Returns a boolean indicating whether the strings in the two SVs are |
| 2594 | identical. |
| 2595 | |
| 2596 | I32 sv_eq _((SV* sv1, SV* sv2)); |
| 2597 | |
| 2598 | =item SvGETMAGIC |
| 2599 | |
| 2600 | Invokes C<mg_get> on an SV if it has 'get' magic. This macro evaluates |
| 2601 | its argument more than once. |
| 2602 | |
| 2603 | void SvGETMAGIC( SV *sv ) |
| 2604 | |
| 2605 | =item SvGROW |
| 2606 | |
| 2607 | Expands the character buffer in the SV. Calls C<sv_grow> to perform the |
| 2608 | expansion if necessary. Returns a pointer to the character buffer. |
| 2609 | |
| 2610 | char * SvGROW( SV* sv, int len ) |
| 2611 | |
| 2612 | =item sv_grow |
| 2613 | |
| 2614 | Expands the character buffer in the SV. This will use C<sv_unref> and will |
| 2615 | upgrade the SV to C<SVt_PV>. Returns a pointer to the character buffer. |
| 2616 | Use C<SvGROW>. |
| 2617 | |
| 2618 | =item sv_inc |
| 2619 | |
| 2620 | Auto-increment of the value in the SV. |
| 2621 | |
| 2622 | void sv_inc _((SV* sv)); |
| 2623 | |
| 2624 | =item SvIOK |
| 2625 | |
| 2626 | Returns a boolean indicating whether the SV contains an integer. |
| 2627 | |
| 2628 | int SvIOK (SV* SV) |
| 2629 | |
| 2630 | =item SvIOK_off |
| 2631 | |
| 2632 | Unsets the IV status of an SV. |
| 2633 | |
| 2634 | SvIOK_off (SV* sv) |
| 2635 | |
| 2636 | =item SvIOK_on |
| 2637 | |
| 2638 | Tells an SV that it is an integer. |
| 2639 | |
| 2640 | SvIOK_on (SV* sv) |
| 2641 | |
| 2642 | =item SvIOK_only |
| 2643 | |
| 2644 | Tells an SV that it is an integer and disables all other OK bits. |
| 2645 | |
| 2646 | SvIOK_on (SV* sv) |
| 2647 | |
| 2648 | =item SvIOKp |
| 2649 | |
| 2650 | Returns a boolean indicating whether the SV contains an integer. Checks the |
| 2651 | B<private> setting. Use C<SvIOK>. |
| 2652 | |
| 2653 | int SvIOKp (SV* SV) |
| 2654 | |
| 2655 | =item sv_isa |
| 2656 | |
| 2657 | Returns a boolean indicating whether the SV is blessed into the specified |
| 2658 | class. This does not know how to check for subtype, so it doesn't work in |
| 2659 | an inheritance relationship. |
| 2660 | |
| 2661 | int sv_isa _((SV* sv, char* name)); |
| 2662 | |
| 2663 | =item SvIV |
| 2664 | |
| 2665 | Returns the integer which is in the SV. |
| 2666 | |
| 2667 | int SvIV (SV* sv) |
| 2668 | |
| 2669 | =item sv_isobject |
| 2670 | |
| 2671 | Returns a boolean indicating whether the SV is an RV pointing to a blessed |
| 2672 | object. If the SV is not an RV, or if the object is not blessed, then this |
| 2673 | will return false. |
| 2674 | |
| 2675 | int sv_isobject _((SV* sv)); |
| 2676 | |
| 2677 | =item SvIVX |
| 2678 | |
| 2679 | Returns the integer which is stored in the SV. |
| 2680 | |
| 2681 | int SvIVX (SV* sv); |
| 2682 | |
| 2683 | =item SvLEN |
| 2684 | |
| 2685 | Returns the size of the string buffer in the SV. See C<SvCUR>. |
| 2686 | |
| 2687 | int SvLEN (SV* sv) |
| 2688 | |
| 2689 | =item sv_len |
| 2690 | |
| 2691 | Returns the length of the string in the SV. Use C<SvCUR>. |
| 2692 | |
| 2693 | STRLEN sv_len _((SV* sv)); |
| 2694 | |
| 2695 | =item sv_magic |
| 2696 | |
| 2697 | Adds magic to an SV. |
| 2698 | |
| 2699 | void sv_magic _((SV* sv, SV* obj, int how, char* name, I32 namlen)); |
| 2700 | |
| 2701 | =item sv_mortalcopy |
| 2702 | |
| 2703 | Creates a new SV which is a copy of the original SV. The new SV is marked |
| 2704 | as mortal. |
| 2705 | |
| 2706 | SV* sv_mortalcopy _((SV* oldsv)); |
| 2707 | |
| 2708 | =item SvOK |
| 2709 | |
| 2710 | Returns a boolean indicating whether the value is an SV. |
| 2711 | |
| 2712 | int SvOK (SV* sv) |
| 2713 | |
| 2714 | =item sv_newmortal |
| 2715 | |
| 2716 | Creates a new SV which is mortal. The reference count of the SV is set to 1. |
| 2717 | |
| 2718 | SV* sv_newmortal _((void)); |
| 2719 | |
| 2720 | =item sv_no |
| 2721 | |
| 2722 | This is the C<false> SV. See C<sv_yes>. Always refer to this as C<&sv_no>. |
| 2723 | |
| 2724 | =item SvNIOK |
| 2725 | |
| 2726 | Returns a boolean indicating whether the SV contains a number, integer or |
| 2727 | double. |
| 2728 | |
| 2729 | int SvNIOK (SV* SV) |
| 2730 | |
| 2731 | =item SvNIOK_off |
| 2732 | |
| 2733 | Unsets the NV/IV status of an SV. |
| 2734 | |
| 2735 | SvNIOK_off (SV* sv) |
| 2736 | |
| 2737 | =item SvNIOKp |
| 2738 | |
| 2739 | Returns a boolean indicating whether the SV contains a number, integer or |
| 2740 | double. Checks the B<private> setting. Use C<SvNIOK>. |
| 2741 | |
| 2742 | int SvNIOKp (SV* SV) |
| 2743 | |
| 2744 | =item SvNOK |
| 2745 | |
| 2746 | Returns a boolean indicating whether the SV contains a double. |
| 2747 | |
| 2748 | int SvNOK (SV* SV) |
| 2749 | |
| 2750 | =item SvNOK_off |
| 2751 | |
| 2752 | Unsets the NV status of an SV. |
| 2753 | |
| 2754 | SvNOK_off (SV* sv) |
| 2755 | |
| 2756 | =item SvNOK_on |
| 2757 | |
| 2758 | Tells an SV that it is a double. |
| 2759 | |
| 2760 | SvNOK_on (SV* sv) |
| 2761 | |
| 2762 | =item SvNOK_only |
| 2763 | |
| 2764 | Tells an SV that it is a double and disables all other OK bits. |
| 2765 | |
| 2766 | SvNOK_on (SV* sv) |
| 2767 | |
| 2768 | =item SvNOKp |
| 2769 | |
| 2770 | Returns a boolean indicating whether the SV contains a double. Checks the |
| 2771 | B<private> setting. Use C<SvNOK>. |
| 2772 | |
| 2773 | int SvNOKp (SV* SV) |
| 2774 | |
| 2775 | =item SvNV |
| 2776 | |
| 2777 | Returns the double which is stored in the SV. |
| 2778 | |
| 2779 | double SvNV (SV* sv); |
| 2780 | |
| 2781 | =item SvNVX |
| 2782 | |
| 2783 | Returns the double which is stored in the SV. |
| 2784 | |
| 2785 | double SvNVX (SV* sv); |
| 2786 | |
| 2787 | =item SvPOK |
| 2788 | |
| 2789 | Returns a boolean indicating whether the SV contains a character string. |
| 2790 | |
| 2791 | int SvPOK (SV* SV) |
| 2792 | |
| 2793 | =item SvPOK_off |
| 2794 | |
| 2795 | Unsets the PV status of an SV. |
| 2796 | |
| 2797 | SvPOK_off (SV* sv) |
| 2798 | |
| 2799 | =item SvPOK_on |
| 2800 | |
| 2801 | Tells an SV that it is a string. |
| 2802 | |
| 2803 | SvPOK_on (SV* sv) |
| 2804 | |
| 2805 | =item SvPOK_only |
| 2806 | |
| 2807 | Tells an SV that it is a string and disables all other OK bits. |
| 2808 | |
| 2809 | SvPOK_on (SV* sv) |
| 2810 | |
| 2811 | =item SvPOKp |
| 2812 | |
| 2813 | Returns a boolean indicating whether the SV contains a character string. |
| 2814 | Checks the B<private> setting. Use C<SvPOK>. |
| 2815 | |
| 2816 | int SvPOKp (SV* SV) |
| 2817 | |
| 2818 | =item SvPV |
| 2819 | |
| 2820 | Returns a pointer to the string in the SV, or a stringified form of the SV |
| 2821 | if the SV does not contain a string. If C<len> is C<na> then Perl will |
| 2822 | handle the length on its own. Handles 'get' magic. |
| 2823 | |
| 2824 | char * SvPV (SV* sv, int len ) |
| 2825 | |
| 2826 | =item SvPVX |
| 2827 | |
| 2828 | Returns a pointer to the string in the SV. The SV must contain a string. |
| 2829 | |
| 2830 | char * SvPVX (SV* sv) |
| 2831 | |
| 2832 | =item SvREFCNT |
| 2833 | |
| 2834 | Returns the value of the object's reference count. |
| 2835 | |
| 2836 | int SvREFCNT (SV* sv); |
| 2837 | |
| 2838 | =item SvREFCNT_dec |
| 2839 | |
| 2840 | Decrements the reference count of the given SV. |
| 2841 | |
| 2842 | void SvREFCNT_dec (SV* sv) |
| 2843 | |
| 2844 | =item SvREFCNT_inc |
| 2845 | |
| 2846 | Increments the reference count of the given SV. |
| 2847 | |
| 2848 | void SvREFCNT_inc (SV* sv) |
| 2849 | |
| 2850 | =item SvROK |
| 2851 | |
| 2852 | Tests if the SV is an RV. |
| 2853 | |
| 2854 | int SvROK (SV* sv) |
| 2855 | |
| 2856 | =item SvROK_off |
| 2857 | |
| 2858 | Unsets the RV status of an SV. |
| 2859 | |
| 2860 | SvROK_off (SV* sv) |
| 2861 | |
| 2862 | =item SvROK_on |
| 2863 | |
| 2864 | Tells an SV that it is an RV. |
| 2865 | |
| 2866 | SvROK_on (SV* sv) |
| 2867 | |
| 2868 | =item SvRV |
| 2869 | |
| 2870 | Dereferences an RV to return the SV. |
| 2871 | |
| 2872 | SV* SvRV (SV* sv); |
| 2873 | |
| 2874 | =item SvSETMAGIC |
| 2875 | |
| 2876 | Invokes C<mg_set> on an SV if it has 'set' magic. This macro evaluates |
| 2877 | its argument more than once. |
| 2878 | |
| 2879 | void SvSETMAGIC( SV *sv ) |
| 2880 | |
| 2881 | =item SvTAINT |
| 2882 | |
| 2883 | Taints an SV if tainting is enabled |
| 2884 | |
| 2885 | SvTAINT (SV* sv); |
| 2886 | |
| 2887 | =item SvTAINTED |
| 2888 | |
| 2889 | Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not. |
| 2890 | |
| 2891 | SvTAINTED (SV* sv); |
| 2892 | |
| 2893 | =item SvTAINTED_off |
| 2894 | |
| 2895 | Untaints an SV. Be I<very> careful with this routine, as it short-circuits |
| 2896 | some of Perl's fundamental security features. XS module authors should |
| 2897 | not use this function unless they fully understand all the implications |
| 2898 | of unconditionally untainting the value. Untainting should be done in |
| 2899 | the standard perl fashion, via a carefully crafted regexp, rather than |
| 2900 | directly untainting variables. |
| 2901 | |
| 2902 | SvTAINTED_off (SV* sv); |
| 2903 | |
| 2904 | =item SvTAINTED_on |
| 2905 | |
| 2906 | Marks an SV as tainted. |
| 2907 | |
| 2908 | SvTAINTED_on (SV* sv); |
| 2909 | |
| 2910 | =item SvSetMagicIV |
| 2911 | |
| 2912 | A macro that calls C<sv_setiv>, and invokes 'set' magic on the SV. |
| 2913 | May evaluate arguments more than once. |
| 2914 | |
| 2915 | void SvSetMagicIV (SV* sv, IV num) |
| 2916 | |
| 2917 | =item SvSetMagicNV |
| 2918 | |
| 2919 | A macro that calls C<sv_setnv>, and invokes 'set' magic on the SV. |
| 2920 | May evaluate arguments more than once. |
| 2921 | |
| 2922 | void SvSetMagicNV (SV* sv, double num) |
| 2923 | |
| 2924 | =item SvSetMagicPV |
| 2925 | |
| 2926 | A macro that calls C<sv_setpv>, and invokes 'set' magic on the SV. |
| 2927 | May evaluate arguments more than once. |
| 2928 | |
| 2929 | void SvSetMagicPV (SV* sv, char *ptr) |
| 2930 | |
| 2931 | =item SvSetMagicPVIV |
| 2932 | |
| 2933 | A macro that calls C<sv_setpviv>, and invokes 'set' magic on the SV. |
| 2934 | May evaluate arguments more than once. |
| 2935 | |
| 2936 | void SvSetMagicPVIV (SV* sv, IV num) |
| 2937 | |
| 2938 | =item SvSetMagicPVN |
| 2939 | |
| 2940 | A macro that calls C<sv_setpvn>, and invokes 'set' magic on the SV. |
| 2941 | May evaluate arguments more than once. |
| 2942 | |
| 2943 | void SvSetMagicPVN (SV* sv, char* ptr, STRLEN len) |
| 2944 | |
| 2945 | =item SvSetMagicSV |
| 2946 | |
| 2947 | Same as C<SvSetSV>, but also invokes 'set' magic on the SV. |
| 2948 | May evaluate arguments more than once. |
| 2949 | |
| 2950 | void SvSetMagicSV (SV* dsv, SV* ssv) |
| 2951 | |
| 2952 | =item SvSetMagicSV_nosteal |
| 2953 | |
| 2954 | Same as C<SvSetSV_nosteal>, but also invokes 'set' magic on the SV. |
| 2955 | May evaluate arguments more than once. |
| 2956 | |
| 2957 | void SvSetMagicSV_nosteal (SV* dsv, SV* ssv) |
| 2958 | |
| 2959 | =item SvSetMagicUV |
| 2960 | |
| 2961 | A macro that calls C<sv_setuv>, and invokes 'set' magic on the SV. |
| 2962 | May evaluate arguments more than once. |
| 2963 | |
| 2964 | void SvSetMagicUV (SV* sv, UV num) |
| 2965 | |
| 2966 | =item sv_setiv |
| 2967 | |
| 2968 | Copies an integer into the given SV. Does not handle 'set' magic. |
| 2969 | See C<SvSetMagicIV>. |
| 2970 | |
| 2971 | void sv_setiv _((SV* sv, IV num)); |
| 2972 | |
| 2973 | =item sv_setnv |
| 2974 | |
| 2975 | Copies a double into the given SV. Does not handle 'set' magic. |
| 2976 | See C<SvSetMagicNV>. |
| 2977 | |
| 2978 | void sv_setnv _((SV* sv, double num)); |
| 2979 | |
| 2980 | =item sv_setpv |
| 2981 | |
| 2982 | Copies a string into an SV. The string must be null-terminated. |
| 2983 | Does not handle 'set' magic. See C<SvSetMagicPV>. |
| 2984 | |
| 2985 | void sv_setpv _((SV* sv, char* ptr)); |
| 2986 | |
| 2987 | =item sv_setpviv |
| 2988 | |
| 2989 | Copies an integer into the given SV, also updating its string value. |
| 2990 | Does not handle 'set' magic. See C<SvSetMagicPVIV>. |
| 2991 | |
| 2992 | void sv_setpviv _((SV* sv, IV num)); |
| 2993 | |
| 2994 | =item sv_setpvn |
| 2995 | |
| 2996 | Copies a string into an SV. The C<len> parameter indicates the number of |
| 2997 | bytes to be copied. Does not handle 'set' magic. See C<SvSetMagicPVN>. |
| 2998 | |
| 2999 | void sv_setpvn _((SV* sv, char* ptr, STRLEN len)); |
| 3000 | |
| 3001 | =item sv_setpvf |
| 3002 | |
| 3003 | Processes its arguments like C<sprintf> and sets an SV to the formatted |
| 3004 | output. Does not handle 'set' magic. C<SvSETMAGIC()> must typically |
| 3005 | be called after calling this function to handle 'set' magic. |
| 3006 | |
| 3007 | void sv_setpvf _((SV* sv, const char* pat, ...)); |
| 3008 | |
| 3009 | =item sv_setref_iv |
| 3010 | |
| 3011 | Copies an integer into a new SV, optionally blessing the SV. The C<rv> |
| 3012 | argument will be upgraded to an RV. That RV will be modified to point to |
| 3013 | the new SV. The C<classname> argument indicates the package for the |
| 3014 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
| 3015 | will be returned and will have a reference count of 1. |
| 3016 | |
| 3017 | SV* sv_setref_iv _((SV *rv, char *classname, IV iv)); |
| 3018 | |
| 3019 | =item sv_setref_nv |
| 3020 | |
| 3021 | Copies a double into a new SV, optionally blessing the SV. The C<rv> |
| 3022 | argument will be upgraded to an RV. That RV will be modified to point to |
| 3023 | the new SV. The C<classname> argument indicates the package for the |
| 3024 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
| 3025 | will be returned and will have a reference count of 1. |
| 3026 | |
| 3027 | SV* sv_setref_nv _((SV *rv, char *classname, double nv)); |
| 3028 | |
| 3029 | =item sv_setref_pv |
| 3030 | |
| 3031 | Copies a pointer into a new SV, optionally blessing the SV. The C<rv> |
| 3032 | argument will be upgraded to an RV. That RV will be modified to point to |
| 3033 | the new SV. If the C<pv> argument is NULL then C<sv_undef> will be placed |
| 3034 | into the SV. The C<classname> argument indicates the package for the |
| 3035 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
| 3036 | will be returned and will have a reference count of 1. |
| 3037 | |
| 3038 | SV* sv_setref_pv _((SV *rv, char *classname, void* pv)); |
| 3039 | |
| 3040 | Do not use with integral Perl types such as HV, AV, SV, CV, because those |
| 3041 | objects will become corrupted by the pointer copy process. |
| 3042 | |
| 3043 | Note that C<sv_setref_pvn> copies the string while this copies the pointer. |
| 3044 | |
| 3045 | =item sv_setref_pvn |
| 3046 | |
| 3047 | Copies a string into a new SV, optionally blessing the SV. The length of the |
| 3048 | string must be specified with C<n>. The C<rv> argument will be upgraded to |
| 3049 | an RV. That RV will be modified to point to the new SV. The C<classname> |
| 3050 | argument indicates the package for the blessing. Set C<classname> to |
| 3051 | C<Nullch> to avoid the blessing. The new SV will be returned and will have |
| 3052 | a reference count of 1. |
| 3053 | |
| 3054 | SV* sv_setref_pvn _((SV *rv, char *classname, char* pv, I32 n)); |
| 3055 | |
| 3056 | Note that C<sv_setref_pv> copies the pointer while this copies the string. |
| 3057 | |
| 3058 | =item SvSetSV |
| 3059 | |
| 3060 | Calls C<sv_setsv> if dsv is not the same as ssv. May evaluate arguments |
| 3061 | more than once. |
| 3062 | |
| 3063 | void SvSetSV (SV* dsv, SV* ssv) |
| 3064 | |
| 3065 | =item SvSetSV_nosteal |
| 3066 | |
| 3067 | Calls a non-destructive version of C<sv_setsv> if dsv is not the same as ssv. |
| 3068 | May evaluate arguments more than once. |
| 3069 | |
| 3070 | void SvSetSV_nosteal (SV* dsv, SV* ssv) |
| 3071 | |
| 3072 | =item sv_setsv |
| 3073 | |
| 3074 | Copies the contents of the source SV C<ssv> into the destination SV C<dsv>. |
| 3075 | The source SV may be destroyed if it is mortal. Does not handle 'set' magic. |
| 3076 | See the macro forms C<SvSetSV>, C<SvSetSV_nosteal>, C<SvSetMagicSV> and |
| 3077 | C<SvSetMagicSV_nosteal>. |
| 3078 | |
| 3079 | void sv_setsv _((SV* dsv, SV* ssv)); |
| 3080 | |
| 3081 | =item sv_setuv |
| 3082 | |
| 3083 | Copies an unsigned integer into the given SV. Does not handle 'set' magic. |
| 3084 | See C<SvSetMagicUV>. |
| 3085 | |
| 3086 | void sv_setuv _((SV* sv, UV num)); |
| 3087 | |
| 3088 | =item SvSTASH |
| 3089 | |
| 3090 | Returns the stash of the SV. |
| 3091 | |
| 3092 | HV * SvSTASH (SV* sv) |
| 3093 | |
| 3094 | =item SVt_IV |
| 3095 | |
| 3096 | Integer type flag for scalars. See C<svtype>. |
| 3097 | |
| 3098 | =item SVt_PV |
| 3099 | |
| 3100 | Pointer type flag for scalars. See C<svtype>. |
| 3101 | |
| 3102 | =item SVt_PVAV |
| 3103 | |
| 3104 | Type flag for arrays. See C<svtype>. |
| 3105 | |
| 3106 | =item SVt_PVCV |
| 3107 | |
| 3108 | Type flag for code refs. See C<svtype>. |
| 3109 | |
| 3110 | =item SVt_PVHV |
| 3111 | |
| 3112 | Type flag for hashes. See C<svtype>. |
| 3113 | |
| 3114 | =item SVt_PVMG |
| 3115 | |
| 3116 | Type flag for blessed scalars. See C<svtype>. |
| 3117 | |
| 3118 | =item SVt_NV |
| 3119 | |
| 3120 | Double type flag for scalars. See C<svtype>. |
| 3121 | |
| 3122 | =item SvTRUE |
| 3123 | |
| 3124 | Returns a boolean indicating whether Perl would evaluate the SV as true or |
| 3125 | false, defined or undefined. Does not handle 'get' magic. |
| 3126 | |
| 3127 | int SvTRUE (SV* sv) |
| 3128 | |
| 3129 | =item SvTYPE |
| 3130 | |
| 3131 | Returns the type of the SV. See C<svtype>. |
| 3132 | |
| 3133 | svtype SvTYPE (SV* sv) |
| 3134 | |
| 3135 | =item svtype |
| 3136 | |
| 3137 | An enum of flags for Perl types. These are found in the file B<sv.h> in the |
| 3138 | C<svtype> enum. Test these flags with the C<SvTYPE> macro. |
| 3139 | |
| 3140 | =item SvUPGRADE |
| 3141 | |
| 3142 | Used to upgrade an SV to a more complex form. Uses C<sv_upgrade> to perform |
| 3143 | the upgrade if necessary. See C<svtype>. |
| 3144 | |
| 3145 | bool SvUPGRADE _((SV* sv, svtype mt)); |
| 3146 | |
| 3147 | =item sv_upgrade |
| 3148 | |
| 3149 | Upgrade an SV to a more complex form. Use C<SvUPGRADE>. See C<svtype>. |
| 3150 | |
| 3151 | =item sv_undef |
| 3152 | |
| 3153 | This is the C<undef> SV. Always refer to this as C<&sv_undef>. |
| 3154 | |
| 3155 | =item sv_unref |
| 3156 | |
| 3157 | Unsets the RV status of the SV, and decrements the reference count of |
| 3158 | whatever was being referenced by the RV. This can almost be thought of |
| 3159 | as a reversal of C<newSVrv>. See C<SvROK_off>. |
| 3160 | |
| 3161 | void sv_unref _((SV* sv)); |
| 3162 | |
| 3163 | =item SvUseMagicPVN |
| 3164 | |
| 3165 | =item sv_usepvn |
| 3166 | |
| 3167 | Tells an SV to use C<ptr> to find its string value. Normally the string is |
| 3168 | stored inside the SV but sv_usepvn allows the SV to use an outside string. |
| 3169 | The C<ptr> should point to memory that was allocated by C<malloc>. The |
| 3170 | string length, C<len>, must be supplied. This function will realloc the |
| 3171 | memory pointed to by C<ptr>, so that pointer should not be freed or used by |
| 3172 | the programmer after giving it to sv_usepvn. Does not handle 'set' magic. |
| 3173 | See C<SvUseMagicPVN>. |
| 3174 | |
| 3175 | void sv_usepvn _((SV* sv, char* ptr, STRLEN len)); |
| 3176 | |
| 3177 | =item sv_yes |
| 3178 | |
| 3179 | This is the C<true> SV. See C<sv_no>. Always refer to this as C<&sv_yes>. |
| 3180 | |
| 3181 | =item THIS |
| 3182 | |
| 3183 | Variable which is setup by C<xsubpp> to designate the object in a C++ XSUB. |
| 3184 | This is always the proper type for the C++ object. See C<CLASS> and |
| 3185 | L<perlxs/"Using XS With C++">. |
| 3186 | |
| 3187 | =item toLOWER |
| 3188 | |
| 3189 | Converts the specified character to lowercase. |
| 3190 | |
| 3191 | int toLOWER (char c) |
| 3192 | |
| 3193 | =item toUPPER |
| 3194 | |
| 3195 | Converts the specified character to uppercase. |
| 3196 | |
| 3197 | int toUPPER (char c) |
| 3198 | |
| 3199 | =item warn |
| 3200 | |
| 3201 | This is the XSUB-writer's interface to Perl's C<warn> function. Use this |
| 3202 | function the same way you use the C C<printf> function. See C<croak()>. |
| 3203 | |
| 3204 | =item XPUSHi |
| 3205 | |
| 3206 | Push an integer onto the stack, extending the stack if necessary. Handles |
| 3207 | 'set' magic. See C<PUSHi>. |
| 3208 | |
| 3209 | XPUSHi(int d) |
| 3210 | |
| 3211 | =item XPUSHn |
| 3212 | |
| 3213 | Push a double onto the stack, extending the stack if necessary. Handles 'set' |
| 3214 | magic. See C<PUSHn>. |
| 3215 | |
| 3216 | XPUSHn(double d) |
| 3217 | |
| 3218 | =item XPUSHp |
| 3219 | |
| 3220 | Push a string onto the stack, extending the stack if necessary. The C<len> |
| 3221 | indicates the length of the string. Handles 'set' magic. See C<PUSHp>. |
| 3222 | |
| 3223 | XPUSHp(char *c, int len) |
| 3224 | |
| 3225 | =item XPUSHs |
| 3226 | |
| 3227 | Push an SV onto the stack, extending the stack if necessary. Does not |
| 3228 | handle 'set' magic. See C<PUSHs>. |
| 3229 | |
| 3230 | XPUSHs(sv) |
| 3231 | |
| 3232 | =item XS |
| 3233 | |
| 3234 | Macro to declare an XSUB and its C parameter list. This is handled by |
| 3235 | C<xsubpp>. |
| 3236 | |
| 3237 | =item XSRETURN |
| 3238 | |
| 3239 | Return from XSUB, indicating number of items on the stack. This is usually |
| 3240 | handled by C<xsubpp>. |
| 3241 | |
| 3242 | XSRETURN(int x); |
| 3243 | |
| 3244 | =item XSRETURN_EMPTY |
| 3245 | |
| 3246 | Return an empty list from an XSUB immediately. |
| 3247 | |
| 3248 | XSRETURN_EMPTY; |
| 3249 | |
| 3250 | =item XSRETURN_IV |
| 3251 | |
| 3252 | Return an integer from an XSUB immediately. Uses C<XST_mIV>. |
| 3253 | |
| 3254 | XSRETURN_IV(IV v); |
| 3255 | |
| 3256 | =item XSRETURN_NO |
| 3257 | |
| 3258 | Return C<&sv_no> from an XSUB immediately. Uses C<XST_mNO>. |
| 3259 | |
| 3260 | XSRETURN_NO; |
| 3261 | |
| 3262 | =item XSRETURN_NV |
| 3263 | |
| 3264 | Return an double from an XSUB immediately. Uses C<XST_mNV>. |
| 3265 | |
| 3266 | XSRETURN_NV(NV v); |
| 3267 | |
| 3268 | =item XSRETURN_PV |
| 3269 | |
| 3270 | Return a copy of a string from an XSUB immediately. Uses C<XST_mPV>. |
| 3271 | |
| 3272 | XSRETURN_PV(char *v); |
| 3273 | |
| 3274 | =item XSRETURN_UNDEF |
| 3275 | |
| 3276 | Return C<&sv_undef> from an XSUB immediately. Uses C<XST_mUNDEF>. |
| 3277 | |
| 3278 | XSRETURN_UNDEF; |
| 3279 | |
| 3280 | =item XSRETURN_YES |
| 3281 | |
| 3282 | Return C<&sv_yes> from an XSUB immediately. Uses C<XST_mYES>. |
| 3283 | |
| 3284 | XSRETURN_YES; |
| 3285 | |
| 3286 | =item XST_mIV |
| 3287 | |
| 3288 | Place an integer into the specified position C<i> on the stack. The value is |
| 3289 | stored in a new mortal SV. |
| 3290 | |
| 3291 | XST_mIV( int i, IV v ); |
| 3292 | |
| 3293 | =item XST_mNV |
| 3294 | |
| 3295 | Place a double into the specified position C<i> on the stack. The value is |
| 3296 | stored in a new mortal SV. |
| 3297 | |
| 3298 | XST_mNV( int i, NV v ); |
| 3299 | |
| 3300 | =item XST_mNO |
| 3301 | |
| 3302 | Place C<&sv_no> into the specified position C<i> on the stack. |
| 3303 | |
| 3304 | XST_mNO( int i ); |
| 3305 | |
| 3306 | =item XST_mPV |
| 3307 | |
| 3308 | Place a copy of a string into the specified position C<i> on the stack. The |
| 3309 | value is stored in a new mortal SV. |
| 3310 | |
| 3311 | XST_mPV( int i, char *v ); |
| 3312 | |
| 3313 | =item XST_mUNDEF |
| 3314 | |
| 3315 | Place C<&sv_undef> into the specified position C<i> on the stack. |
| 3316 | |
| 3317 | XST_mUNDEF( int i ); |
| 3318 | |
| 3319 | =item XST_mYES |
| 3320 | |
| 3321 | Place C<&sv_yes> into the specified position C<i> on the stack. |
| 3322 | |
| 3323 | XST_mYES( int i ); |
| 3324 | |
| 3325 | =item XS_VERSION |
| 3326 | |
| 3327 | The version identifier for an XS module. This is usually handled |
| 3328 | automatically by C<ExtUtils::MakeMaker>. See C<XS_VERSION_BOOTCHECK>. |
| 3329 | |
| 3330 | =item XS_VERSION_BOOTCHECK |
| 3331 | |
| 3332 | Macro to verify that a PM module's $VERSION variable matches the XS module's |
| 3333 | C<XS_VERSION> variable. This is usually handled automatically by |
| 3334 | C<xsubpp>. See L<perlxs/"The VERSIONCHECK: Keyword">. |
| 3335 | |
| 3336 | =item Zero |
| 3337 | |
| 3338 | The XSUB-writer's interface to the C C<memzero> function. The C<d> is the |
| 3339 | destination, C<n> is the number of items, and C<t> is the type. |
| 3340 | |
| 3341 | (void) Zero( d, n, t ); |
| 3342 | |
| 3343 | =back |
| 3344 | |
| 3345 | =head1 EDITOR |
| 3346 | |
| 3347 | Jeff Okamoto <F<okamoto@corp.hp.com>> |
| 3348 | |
| 3349 | With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, |
| 3350 | Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil |
| 3351 | Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, |
| 3352 | Stephen McCamant, and Gurusamy Sarathy. |
| 3353 | |
| 3354 | API Listing by Dean Roehrich <F<roehrich@cray.com>>. |
| 3355 | |
| 3356 | =head1 DATE |
| 3357 | |
| 3358 | Version 31.8: 1997/5/17 |