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