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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 | |
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11 | =head1 Variables |
12 | |
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13 | =head2 Datatypes |
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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 | |
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21 | Each typedef has specific routines that manipulate the various data types. |
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22 | |
23 | =head2 What is an "IV"? |
24 | |
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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). |
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27 | |
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28 | Perl also uses two special typedefs, I32 and I16, which will always be at |
29 | least 32-bits and 16-bits long, respectively. |
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30 | |
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31 | =head2 Working with SVs |
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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 | |
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44 | To change the value of an *already-existing* SV, there are five routines: |
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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 |
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53 | assigned by using C<sv_setpvn> or C<newSVpv>, or you may allow Perl to |
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54 | calculate the length by using C<sv_setpv> or by specifying 0 as the second |
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55 | argument to C<newSVpv>. Be warned, though, that Perl will determine the |
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56 | string's length by using C<strlen>, which depends on the string terminating |
57 | with a NUL character. |
58 | |
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59 | All SVs that will contain strings should, but need not, be terminated |
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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 | |
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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 |
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80 | NULs and might not be terminated by a NUL. |
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81 | |
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82 | If you want to know if the scalar value is TRUE, you can use: |
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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 |
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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 |
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95 | C<SvGROW(sv, len + 1)>). |
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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 | |
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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. |
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116 | |
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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 | |
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130 | If you know the name of a scalar variable, you can get a pointer to its SV |
131 | by using the following: |
132 | |
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133 | SV* perl_get_sv("package::varname", FALSE); |
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134 | |
135 | This returns NULL if the variable does not exist. |
136 | |
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137 | If you want to know if this variable (or any other SV) is actually C<defined>, |
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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, |
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161 | bus error, or just weird results. Change the zero to C<&sv_undef> in the first |
162 | line and all will be well. |
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163 | |
164 | To free an SV that you've created, call C<SvREFCNT_dec(SV*)>. Normally this |
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165 | call is not necessary (see L<Reference Counts and Mortality>). |
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166 | |
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167 | =head2 What's Really Stored in an SV? |
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168 | |
169 | Recall that the usual method of determining the type of scalar you have is |
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170 | to use C<Sv*OK> macros. Because a scalar can be both a number and a string, |
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171 | usually these macros will always return TRUE and calling the C<Sv*V> |
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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 |
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183 | stored in your SV. The "p" stands for private. |
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184 | |
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185 | In general, though, it's best to use the C<Sv*V> macros. |
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186 | |
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187 | =head2 Working with AVs |
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188 | |
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189 | There are two ways to create and load an AV. The first method creates an |
190 | empty AV: |
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191 | |
192 | AV* newAV(); |
193 | |
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194 | The second method both creates the AV and initially populates it with SVs: |
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195 | |
196 | AV* av_make(I32 num, SV **ptr); |
197 | |
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198 | The second argument points to an array containing C<num> C<SV*>'s. Once the |
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199 | AV has been created, the SVs can be destroyed, if so desired. |
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200 | |
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201 | Once the AV has been created, the following operations are possible on AVs: |
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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 | |
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215 | I32 av_len(AV*); |
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216 | SV** av_fetch(AV*, I32 key, I32 lval); |
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217 | SV** av_store(AV*, I32 key, SV* val); |
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218 | |
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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. |
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226 | |
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227 | void av_clear(AV*); |
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228 | void av_undef(AV*); |
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229 | void av_extend(AV*, I32 key); |
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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. |
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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 | |
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241 | AV* perl_get_av("package::varname", FALSE); |
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242 | |
243 | This returns NULL if the variable does not exist. |
244 | |
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245 | =head2 Working with HVs |
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246 | |
247 | To create an HV, you use the following routine: |
248 | |
249 | HV* newHV(); |
250 | |
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251 | Once the HV has been created, the following operations are possible on HVs: |
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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 | |
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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 |
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259 | scalar being stored, and C<hash> is the precomputed hash value (zero if |
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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. |
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264 | |
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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. |
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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); |
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273 | SV* hv_delete(HV*, char* key, U32 klen, I32 flags); |
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274 | |
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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 | |
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278 | And more miscellaneous functions: |
279 | |
280 | void hv_clear(HV*); |
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281 | void hv_undef(HV*); |
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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. |
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286 | |
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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 | |
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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 */ |
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301 | SV* hv_iterval(HV*, HE* entry); |
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302 | /* Return a SV pointer to the value of the HE |
303 | structure */ |
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304 | SV* hv_iternextsv(HV*, char** key, I32* retlen); |
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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 */ |
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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 | |
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313 | HV* perl_get_hv("package::varname", FALSE); |
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314 | |
315 | This returns NULL if the variable does not exist. |
316 | |
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317 | The hash algorithm is defined in the C<PERL_HASH(hash, key, klen)> macro: |
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318 | |
319 | i = klen; |
320 | hash = 0; |
321 | s = key; |
322 | while (i--) |
323 | hash = hash * 33 + *s++; |
324 | |
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325 | =head2 Hash API Extensions |
326 | |
327 | Beginning with version 5.004, the following functions are also supported: |
328 | |
329 | HE* hv_fetch_ent (HV* tb, SV* key, I32 lval, U32 hash); |
330 | HE* hv_store_ent (HV* tb, SV* key, SV* val, U32 hash); |
331 | |
332 | bool hv_exists_ent (HV* tb, SV* key, U32 hash); |
333 | SV* hv_delete_ent (HV* tb, SV* key, I32 flags, U32 hash); |
334 | |
335 | SV* hv_iterkeysv (HE* entry); |
336 | |
337 | Note that these functions take C<SV*> keys, which simplifies writing |
338 | of extension code that deals with hash structures. These functions |
339 | also allow passing of C<SV*> keys to C<tie> functions without forcing |
340 | you to stringify the keys (unlike the previous set of functions). |
341 | |
342 | They also return and accept whole hash entries (C<HE*>), making their |
343 | use more efficient (since the hash number for a particular string |
344 | doesn't have to be recomputed every time). See L<API LISTING> later in |
345 | this document for detailed descriptions. |
346 | |
347 | The following macros must always be used to access the contents of hash |
348 | entries. Note that the arguments to these macros must be simple |
349 | variables, since they may get evaluated more than once. See |
350 | L<API LISTING> later in this document for detailed descriptions of these |
351 | macros. |
352 | |
353 | HePV(HE* he, STRLEN len) |
354 | HeVAL(HE* he) |
355 | HeHASH(HE* he) |
356 | HeSVKEY(HE* he) |
357 | HeSVKEY_force(HE* he) |
358 | HeSVKEY_set(HE* he, SV* sv) |
359 | |
360 | These two lower level macros are defined, but must only be used when |
361 | dealing with keys that are not C<SV*>s: |
362 | |
363 | HeKEY(HE* he) |
364 | HeKLEN(HE* he) |
365 | |
366 | |
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367 | =head2 References |
368 | |
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369 | References are a special type of scalar that point to other data types |
370 | (including references). |
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371 | |
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372 | To create a reference, use either of the following functions: |
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373 | |
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374 | SV* newRV_inc((SV*) thing); |
375 | SV* newRV_noinc((SV*) thing); |
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376 | |
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377 | The C<thing> argument can be any of an C<SV*>, C<AV*>, or C<HV*>. The |
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378 | functions are identical except that C<newRV_inc> increments the reference |
379 | count of the C<thing>, while C<newRV_noinc> does not. For historical |
380 | reasons, C<newRV> is a synonym for C<newRV_inc>. |
381 | |
382 | Once you have a reference, you can use the following macro to dereference |
383 | the reference: |
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384 | |
385 | SvRV(SV*) |
386 | |
387 | then call the appropriate routines, casting the returned C<SV*> to either an |
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388 | C<AV*> or C<HV*>, if required. |
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389 | |
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390 | To determine if an SV is a reference, you can use the following macro: |
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391 | |
392 | SvROK(SV*) |
393 | |
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394 | To discover what type of value the reference refers to, use the following |
395 | macro and then check the return value. |
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396 | |
397 | SvTYPE(SvRV(SV*)) |
398 | |
399 | The most useful types that will be returned are: |
400 | |
401 | SVt_IV Scalar |
402 | SVt_NV Scalar |
403 | SVt_PV Scalar |
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404 | SVt_RV Scalar |
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405 | SVt_PVAV Array |
406 | SVt_PVHV Hash |
407 | SVt_PVCV Code |
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408 | SVt_PVGV Glob (possible a file handle) |
409 | SVt_PVMG Blessed or Magical Scalar |
410 | |
411 | See the sv.h header file for more details. |
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412 | |
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413 | =head2 Blessed References and Class Objects |
414 | |
415 | References are also used to support object-oriented programming. In the |
416 | OO lexicon, an object is simply a reference that has been blessed into a |
417 | package (or class). Once blessed, the programmer may now use the reference |
418 | to access the various methods in the class. |
419 | |
420 | A reference can be blessed into a package with the following function: |
421 | |
422 | SV* sv_bless(SV* sv, HV* stash); |
423 | |
424 | The C<sv> argument must be a reference. The C<stash> argument specifies |
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425 | which class the reference will belong to. See |
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426 | L<Stashes and Globs> for information on converting class names into stashes. |
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427 | |
428 | /* Still under construction */ |
429 | |
430 | Upgrades rv to reference if not already one. Creates new SV for rv to |
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431 | point to. If C<classname> is non-null, the SV is blessed into the specified |
432 | class. SV is returned. |
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433 | |
434 | SV* newSVrv(SV* rv, char* classname); |
435 | |
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436 | Copies integer or double into an SV whose reference is C<rv>. SV is blessed |
437 | if C<classname> is non-null. |
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438 | |
439 | SV* sv_setref_iv(SV* rv, char* classname, IV iv); |
440 | SV* sv_setref_nv(SV* rv, char* classname, NV iv); |
441 | |
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442 | Copies the pointer value (I<the address, not the string!>) into an SV whose |
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443 | reference is rv. SV is blessed if C<classname> is non-null. |
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444 | |
445 | SV* sv_setref_pv(SV* rv, char* classname, PV iv); |
446 | |
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447 | Copies string into an SV whose reference is C<rv>. Set length to 0 to let |
448 | Perl calculate the string length. SV is blessed if C<classname> is non-null. |
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449 | |
450 | SV* sv_setref_pvn(SV* rv, char* classname, PV iv, int length); |
451 | |
452 | int sv_isa(SV* sv, char* name); |
453 | int sv_isobject(SV* sv); |
454 | |
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455 | =head2 Creating New Variables |
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456 | |
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457 | To create a new Perl variable with an undef value which can be accessed from |
458 | your Perl script, use the following routines, depending on the variable type. |
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459 | |
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460 | SV* perl_get_sv("package::varname", TRUE); |
461 | AV* perl_get_av("package::varname", TRUE); |
462 | HV* perl_get_hv("package::varname", TRUE); |
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463 | |
464 | Notice the use of TRUE as the second parameter. The new variable can now |
465 | be set, using the routines appropriate to the data type. |
466 | |
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467 | There are additional macros whose values may be bitwise OR'ed with the |
468 | C<TRUE> argument to enable certain extra features. Those bits are: |
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469 | |
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470 | GV_ADDMULTI Marks the variable as multiply defined, thus preventing the |
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471 | "Name <varname> used only once: possible typo" warning. |
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472 | GV_ADDWARN Issues the warning "Had to create <varname> unexpectedly" if |
473 | the variable did not exist before the function was called. |
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474 | |
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475 | If you do not specify a package name, the variable is created in the current |
476 | package. |
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477 | |
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478 | =head2 Reference Counts and Mortality |
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479 | |
54310121 |
480 | Perl uses an reference count-driven garbage collection mechanism. SVs, |
481 | AVs, or HVs (xV for short in the following) start their life with a |
55497cff |
482 | reference count of 1. If the reference count of an xV ever drops to 0, |
07fa94a1 |
483 | then it will be destroyed and its memory made available for reuse. |
55497cff |
484 | |
485 | This normally doesn't happen at the Perl level unless a variable is |
5f05dabc |
486 | undef'ed or the last variable holding a reference to it is changed or |
487 | overwritten. At the internal level, however, reference counts can be |
55497cff |
488 | manipulated with the following macros: |
489 | |
490 | int SvREFCNT(SV* sv); |
5f05dabc |
491 | SV* SvREFCNT_inc(SV* sv); |
55497cff |
492 | void SvREFCNT_dec(SV* sv); |
493 | |
494 | However, there is one other function which manipulates the reference |
07fa94a1 |
495 | count of its argument. The C<newRV_inc> function, you will recall, |
496 | creates a reference to the specified argument. As a side effect, |
497 | it increments the argument's reference count. If this is not what |
498 | you want, use C<newRV_noinc> instead. |
499 | |
500 | For example, imagine you want to return a reference from an XSUB function. |
501 | Inside the XSUB routine, you create an SV which initially has a reference |
502 | count of one. Then you call C<newRV_inc>, passing it the just-created SV. |
5f05dabc |
503 | This returns the reference as a new SV, but the reference count of the |
504 | SV you passed to C<newRV_inc> has been incremented to two. Now you |
07fa94a1 |
505 | return the reference from the XSUB routine and forget about the SV. |
506 | But Perl hasn't! Whenever the returned reference is destroyed, the |
507 | reference count of the original SV is decreased to one and nothing happens. |
508 | The SV will hang around without any way to access it until Perl itself |
509 | terminates. This is a memory leak. |
5f05dabc |
510 | |
511 | The correct procedure, then, is to use C<newRV_noinc> instead of |
faed5253 |
512 | C<newRV_inc>. Then, if and when the last reference is destroyed, |
513 | the reference count of the SV will go to zero and it will be destroyed, |
07fa94a1 |
514 | stopping any memory leak. |
55497cff |
515 | |
5f05dabc |
516 | There are some convenience functions available that can help with the |
54310121 |
517 | destruction of xVs. These functions introduce the concept of "mortality". |
07fa94a1 |
518 | An xV that is mortal has had its reference count marked to be decremented, |
519 | but not actually decremented, until "a short time later". Generally the |
520 | term "short time later" means a single Perl statement, such as a call to |
54310121 |
521 | an XSUB function. The actual determinant for when mortal xVs have their |
07fa94a1 |
522 | reference count decremented depends on two macros, SAVETMPS and FREETMPS. |
523 | See L<perlcall> and L<perlxs> for more details on these macros. |
55497cff |
524 | |
525 | "Mortalization" then is at its simplest a deferred C<SvREFCNT_dec>. |
526 | However, if you mortalize a variable twice, the reference count will |
527 | later be decremented twice. |
528 | |
529 | You should be careful about creating mortal variables. Strange things |
530 | can happen if you make the same value mortal within multiple contexts, |
5f05dabc |
531 | or if you make a variable mortal multiple times. |
a0d0e21e |
532 | |
533 | To create a mortal variable, use the functions: |
534 | |
535 | SV* sv_newmortal() |
536 | SV* sv_2mortal(SV*) |
537 | SV* sv_mortalcopy(SV*) |
538 | |
5f05dabc |
539 | The first call creates a mortal SV, the second converts an existing |
540 | SV to a mortal SV (and thus defers a call to C<SvREFCNT_dec>), and the |
541 | third creates a mortal copy of an existing SV. |
a0d0e21e |
542 | |
54310121 |
543 | The mortal routines are not just for SVs -- AVs and HVs can be |
faed5253 |
544 | made mortal by passing their address (type-casted to C<SV*>) to the |
07fa94a1 |
545 | C<sv_2mortal> or C<sv_mortalcopy> routines. |
a0d0e21e |
546 | |
5f05dabc |
547 | =head2 Stashes and Globs |
a0d0e21e |
548 | |
aa689395 |
549 | A "stash" is a hash that contains all of the different objects that |
550 | are contained within a package. Each key of the stash is a symbol |
551 | name (shared by all the different types of objects that have the same |
552 | name), and each value in the hash table is a GV (Glob Value). This GV |
553 | in turn contains references to the various objects of that name, |
554 | including (but not limited to) the following: |
cb1a09d0 |
555 | |
a0d0e21e |
556 | Scalar Value |
557 | Array Value |
558 | Hash Value |
559 | File Handle |
560 | Directory Handle |
561 | Format |
562 | Subroutine |
563 | |
5f05dabc |
564 | There is a single stash called "defstash" that holds the items that exist |
565 | in the "main" package. To get at the items in other packages, append the |
566 | string "::" to the package name. The items in the "Foo" package are in |
567 | the stash "Foo::" in defstash. The items in the "Bar::Baz" package are |
568 | in the stash "Baz::" in "Bar::"'s stash. |
a0d0e21e |
569 | |
d1b91892 |
570 | To get the stash pointer for a particular package, use the function: |
a0d0e21e |
571 | |
572 | HV* gv_stashpv(char* name, I32 create) |
573 | HV* gv_stashsv(SV*, I32 create) |
574 | |
575 | The first function takes a literal string, the second uses the string stored |
d1b91892 |
576 | in the SV. Remember that a stash is just a hash table, so you get back an |
cb1a09d0 |
577 | C<HV*>. The C<create> flag will create a new package if it is set. |
a0d0e21e |
578 | |
579 | The name that C<gv_stash*v> wants is the name of the package whose symbol table |
580 | you want. The default package is called C<main>. If you have multiply nested |
d1b91892 |
581 | packages, pass their names to C<gv_stash*v>, separated by C<::> as in the Perl |
582 | language itself. |
a0d0e21e |
583 | |
584 | Alternately, if you have an SV that is a blessed reference, you can find |
585 | out the stash pointer by using: |
586 | |
587 | HV* SvSTASH(SvRV(SV*)); |
588 | |
589 | then use the following to get the package name itself: |
590 | |
591 | char* HvNAME(HV* stash); |
592 | |
5f05dabc |
593 | If you need to bless or re-bless an object you can use the following |
594 | function: |
a0d0e21e |
595 | |
596 | SV* sv_bless(SV*, HV* stash) |
597 | |
598 | where the first argument, an C<SV*>, must be a reference, and the second |
599 | argument is a stash. The returned C<SV*> can now be used in the same way |
600 | as any other SV. |
601 | |
d1b91892 |
602 | For more information on references and blessings, consult L<perlref>. |
603 | |
54310121 |
604 | =head2 Double-Typed SVs |
0a753a76 |
605 | |
606 | Scalar variables normally contain only one type of value, an integer, |
607 | double, pointer, or reference. Perl will automatically convert the |
608 | actual scalar data from the stored type into the requested type. |
609 | |
610 | Some scalar variables contain more than one type of scalar data. For |
611 | example, the variable C<$!> contains either the numeric value of C<errno> |
612 | or its string equivalent from either C<strerror> or C<sys_errlist[]>. |
613 | |
614 | To force multiple data values into an SV, you must do two things: use the |
615 | C<sv_set*v> routines to add the additional scalar type, then set a flag |
616 | so that Perl will believe it contains more than one type of data. The |
617 | four macros to set the flags are: |
618 | |
619 | SvIOK_on |
620 | SvNOK_on |
621 | SvPOK_on |
622 | SvROK_on |
623 | |
624 | The particular macro you must use depends on which C<sv_set*v> routine |
625 | you called first. This is because every C<sv_set*v> routine turns on |
626 | only the bit for the particular type of data being set, and turns off |
627 | all the rest. |
628 | |
629 | For example, to create a new Perl variable called "dberror" that contains |
630 | both the numeric and descriptive string error values, you could use the |
631 | following code: |
632 | |
633 | extern int dberror; |
634 | extern char *dberror_list; |
635 | |
636 | SV* sv = perl_get_sv("dberror", TRUE); |
637 | sv_setiv(sv, (IV) dberror); |
638 | sv_setpv(sv, dberror_list[dberror]); |
639 | SvIOK_on(sv); |
640 | |
641 | If the order of C<sv_setiv> and C<sv_setpv> had been reversed, then the |
642 | macro C<SvPOK_on> would need to be called instead of C<SvIOK_on>. |
643 | |
644 | =head2 Magic Variables |
a0d0e21e |
645 | |
d1b91892 |
646 | [This section still under construction. Ignore everything here. Post no |
647 | bills. Everything not permitted is forbidden.] |
648 | |
d1b91892 |
649 | Any SV may be magical, that is, it has special features that a normal |
650 | SV does not have. These features are stored in the SV structure in a |
5f05dabc |
651 | linked list of C<struct magic>'s, typedef'ed to C<MAGIC>. |
d1b91892 |
652 | |
653 | struct magic { |
654 | MAGIC* mg_moremagic; |
655 | MGVTBL* mg_virtual; |
656 | U16 mg_private; |
657 | char mg_type; |
658 | U8 mg_flags; |
659 | SV* mg_obj; |
660 | char* mg_ptr; |
661 | I32 mg_len; |
662 | }; |
663 | |
664 | Note this is current as of patchlevel 0, and could change at any time. |
665 | |
666 | =head2 Assigning Magic |
667 | |
668 | Perl adds magic to an SV using the sv_magic function: |
669 | |
670 | void sv_magic(SV* sv, SV* obj, int how, char* name, I32 namlen); |
671 | |
672 | The C<sv> argument is a pointer to the SV that is to acquire a new magical |
673 | feature. |
674 | |
675 | If C<sv> is not already magical, Perl uses the C<SvUPGRADE> macro to |
676 | set the C<SVt_PVMG> flag for the C<sv>. Perl then continues by adding |
677 | it to the beginning of the linked list of magical features. Any prior |
678 | entry of the same type of magic is deleted. Note that this can be |
5fb8527f |
679 | overridden, and multiple instances of the same type of magic can be |
d1b91892 |
680 | associated with an SV. |
681 | |
54310121 |
682 | The C<name> and C<namlen> arguments are used to associate a string with |
683 | the magic, typically the name of a variable. C<namlen> is stored in the |
684 | C<mg_len> field and if C<name> is non-null and C<namlen> >= 0 a malloc'd |
d1b91892 |
685 | copy of the name is stored in C<mg_ptr> field. |
686 | |
687 | The sv_magic function uses C<how> to determine which, if any, predefined |
688 | "Magic Virtual Table" should be assigned to the C<mg_virtual> field. |
cb1a09d0 |
689 | See the "Magic Virtual Table" section below. The C<how> argument is also |
690 | stored in the C<mg_type> field. |
d1b91892 |
691 | |
692 | The C<obj> argument is stored in the C<mg_obj> field of the C<MAGIC> |
693 | structure. If it is not the same as the C<sv> argument, the reference |
694 | count of the C<obj> object is incremented. If it is the same, or if |
695 | the C<how> argument is "#", or if it is a null pointer, then C<obj> is |
696 | merely stored, without the reference count being incremented. |
697 | |
cb1a09d0 |
698 | There is also a function to add magic to an C<HV>: |
699 | |
700 | void hv_magic(HV *hv, GV *gv, int how); |
701 | |
702 | This simply calls C<sv_magic> and coerces the C<gv> argument into an C<SV>. |
703 | |
704 | To remove the magic from an SV, call the function sv_unmagic: |
705 | |
706 | void sv_unmagic(SV *sv, int type); |
707 | |
708 | The C<type> argument should be equal to the C<how> value when the C<SV> |
709 | was initially made magical. |
710 | |
d1b91892 |
711 | =head2 Magic Virtual Tables |
712 | |
713 | The C<mg_virtual> field in the C<MAGIC> structure is a pointer to a |
714 | C<MGVTBL>, which is a structure of function pointers and stands for |
715 | "Magic Virtual Table" to handle the various operations that might be |
716 | applied to that variable. |
717 | |
718 | The C<MGVTBL> has five pointers to the following routine types: |
719 | |
720 | int (*svt_get)(SV* sv, MAGIC* mg); |
721 | int (*svt_set)(SV* sv, MAGIC* mg); |
722 | U32 (*svt_len)(SV* sv, MAGIC* mg); |
723 | int (*svt_clear)(SV* sv, MAGIC* mg); |
724 | int (*svt_free)(SV* sv, MAGIC* mg); |
725 | |
726 | This MGVTBL structure is set at compile-time in C<perl.h> and there are |
727 | currently 19 types (or 21 with overloading turned on). These different |
728 | structures contain pointers to various routines that perform additional |
729 | actions depending on which function is being called. |
730 | |
731 | Function pointer Action taken |
732 | ---------------- ------------ |
733 | svt_get Do something after the value of the SV is retrieved. |
734 | svt_set Do something after the SV is assigned a value. |
735 | svt_len Report on the SV's length. |
736 | svt_clear Clear something the SV represents. |
737 | svt_free Free any extra storage associated with the SV. |
738 | |
739 | For instance, the MGVTBL structure called C<vtbl_sv> (which corresponds |
740 | to an C<mg_type> of '\0') contains: |
741 | |
742 | { magic_get, magic_set, magic_len, 0, 0 } |
743 | |
744 | Thus, when an SV is determined to be magical and of type '\0', if a get |
745 | operation is being performed, the routine C<magic_get> is called. All |
746 | the various routines for the various magical types begin with C<magic_>. |
747 | |
748 | The current kinds of Magic Virtual Tables are: |
749 | |
07fa94a1 |
750 | mg_type MGVTBL Type of magical |
5f05dabc |
751 | ------- ------ ---------------------------- |
d1b91892 |
752 | \0 vtbl_sv Regexp??? |
753 | A vtbl_amagic Operator Overloading |
754 | a vtbl_amagicelem Operator Overloading |
755 | c 0 Used in Operator Overloading |
756 | B vtbl_bm Boyer-Moore??? |
757 | E vtbl_env %ENV hash |
758 | e vtbl_envelem %ENV hash element |
759 | g vtbl_mglob Regexp /g flag??? |
760 | I vtbl_isa @ISA array |
761 | i vtbl_isaelem @ISA array element |
762 | L 0 (but sets RMAGICAL) Perl Module/Debugger??? |
763 | l vtbl_dbline Debugger? |
44a8e56a |
764 | o vtbl_collxfrm Locale transformation |
d1b91892 |
765 | P vtbl_pack Tied Array or Hash |
766 | p vtbl_packelem Tied Array or Hash element |
767 | q vtbl_packelem Tied Scalar or Handle |
768 | S vtbl_sig Signal Hash |
769 | s vtbl_sigelem Signal Hash element |
770 | t vtbl_taint Taintedness |
771 | U vtbl_uvar ??? |
772 | v vtbl_vec Vector |
773 | x vtbl_substr Substring??? |
e616eb7b |
774 | y vtbl_itervar Shadow "foreach" iterator variable |
d1b91892 |
775 | * vtbl_glob GV??? |
776 | # vtbl_arylen Array Length |
777 | . vtbl_pos $. scalar variable |
5f05dabc |
778 | ~ None Used by certain extensions |
d1b91892 |
779 | |
68dc0745 |
780 | When an uppercase and lowercase letter both exist in the table, then the |
781 | uppercase letter is used to represent some kind of composite type (a list |
782 | or a hash), and the lowercase letter is used to represent an element of |
d1b91892 |
783 | that composite type. |
784 | |
5f05dabc |
785 | The '~' magic type is defined specifically for use by extensions and |
786 | will not be used by perl itself. Extensions can use ~ magic to 'attach' |
787 | private information to variables (typically objects). This is especially |
788 | useful because there is no way for normal perl code to corrupt this |
789 | private information (unlike using extra elements of a hash object). |
790 | |
791 | Note that because multiple extensions may be using ~ magic it is |
792 | important for extensions to take extra care with it. Typically only |
793 | using it on objects blessed into the same class as the extension |
794 | is sufficient. It may also be appropriate to add an I32 'signature' |
795 | at the top of the private data area and check that. |
796 | |
d1b91892 |
797 | =head2 Finding Magic |
798 | |
799 | MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */ |
800 | |
801 | This routine returns a pointer to the C<MAGIC> structure stored in the SV. |
802 | If the SV does not have that magical feature, C<NULL> is returned. Also, |
54310121 |
803 | if the SV is not of type SVt_PVMG, Perl may core dump. |
d1b91892 |
804 | |
805 | int mg_copy(SV* sv, SV* nsv, char* key, STRLEN klen); |
806 | |
807 | This routine checks to see what types of magic C<sv> has. If the mg_type |
68dc0745 |
808 | field is an uppercase letter, then the mg_obj is copied to C<nsv>, but |
809 | the mg_type field is changed to be the lowercase letter. |
a0d0e21e |
810 | |
0a753a76 |
811 | =head1 Subroutines |
a0d0e21e |
812 | |
68dc0745 |
813 | =head2 XSUBs and the Argument Stack |
5f05dabc |
814 | |
815 | The XSUB mechanism is a simple way for Perl programs to access C subroutines. |
816 | An XSUB routine will have a stack that contains the arguments from the Perl |
817 | program, and a way to map from the Perl data structures to a C equivalent. |
818 | |
819 | The stack arguments are accessible through the C<ST(n)> macro, which returns |
820 | the C<n>'th stack argument. Argument 0 is the first argument passed in the |
821 | Perl subroutine call. These arguments are C<SV*>, and can be used anywhere |
822 | an C<SV*> is used. |
823 | |
824 | Most of the time, output from the C routine can be handled through use of |
825 | the RETVAL and OUTPUT directives. However, there are some cases where the |
826 | argument stack is not already long enough to handle all the return values. |
827 | An example is the POSIX tzname() call, which takes no arguments, but returns |
828 | two, the local time zone's standard and summer time abbreviations. |
829 | |
830 | To handle this situation, the PPCODE directive is used and the stack is |
831 | extended using the macro: |
832 | |
833 | EXTEND(sp, num); |
834 | |
835 | where C<sp> is the stack pointer, and C<num> is the number of elements the |
836 | stack should be extended by. |
837 | |
838 | Now that there is room on the stack, values can be pushed on it using the |
54310121 |
839 | macros to push IVs, doubles, strings, and SV pointers respectively: |
5f05dabc |
840 | |
841 | PUSHi(IV) |
842 | PUSHn(double) |
843 | PUSHp(char*, I32) |
844 | PUSHs(SV*) |
845 | |
846 | And now the Perl program calling C<tzname>, the two values will be assigned |
847 | as in: |
848 | |
849 | ($standard_abbrev, $summer_abbrev) = POSIX::tzname; |
850 | |
851 | An alternate (and possibly simpler) method to pushing values on the stack is |
852 | to use the macros: |
853 | |
854 | XPUSHi(IV) |
855 | XPUSHn(double) |
856 | XPUSHp(char*, I32) |
857 | XPUSHs(SV*) |
858 | |
859 | These macros automatically adjust the stack for you, if needed. Thus, you |
860 | do not need to call C<EXTEND> to extend the stack. |
861 | |
862 | For more information, consult L<perlxs> and L<perlxstut>. |
863 | |
864 | =head2 Calling Perl Routines from within C Programs |
a0d0e21e |
865 | |
866 | There are four routines that can be used to call a Perl subroutine from |
867 | within a C program. These four are: |
868 | |
869 | I32 perl_call_sv(SV*, I32); |
870 | I32 perl_call_pv(char*, I32); |
871 | I32 perl_call_method(char*, I32); |
872 | I32 perl_call_argv(char*, I32, register char**); |
873 | |
d1b91892 |
874 | The routine most often used is C<perl_call_sv>. The C<SV*> argument |
875 | contains either the name of the Perl subroutine to be called, or a |
876 | reference to the subroutine. The second argument consists of flags |
877 | that control the context in which the subroutine is called, whether |
878 | or not the subroutine is being passed arguments, how errors should be |
879 | trapped, and how to treat return values. |
a0d0e21e |
880 | |
881 | All four routines return the number of arguments that the subroutine returned |
882 | on the Perl stack. |
883 | |
d1b91892 |
884 | When using any of these routines (except C<perl_call_argv>), the programmer |
885 | must manipulate the Perl stack. These include the following macros and |
886 | functions: |
a0d0e21e |
887 | |
888 | dSP |
889 | PUSHMARK() |
890 | PUTBACK |
891 | SPAGAIN |
892 | ENTER |
893 | SAVETMPS |
894 | FREETMPS |
895 | LEAVE |
896 | XPUSH*() |
cb1a09d0 |
897 | POP*() |
a0d0e21e |
898 | |
5f05dabc |
899 | For a detailed description of calling conventions from C to Perl, |
900 | consult L<perlcall>. |
a0d0e21e |
901 | |
5f05dabc |
902 | =head2 Memory Allocation |
a0d0e21e |
903 | |
5f05dabc |
904 | It is suggested that you use the version of malloc that is distributed |
905 | with Perl. It keeps pools of various sizes of unallocated memory in |
07fa94a1 |
906 | order to satisfy allocation requests more quickly. However, on some |
907 | platforms, it may cause spurious malloc or free errors. |
d1b91892 |
908 | |
909 | New(x, pointer, number, type); |
910 | Newc(x, pointer, number, type, cast); |
911 | Newz(x, pointer, number, type); |
912 | |
07fa94a1 |
913 | These three macros are used to initially allocate memory. |
5f05dabc |
914 | |
915 | The first argument C<x> was a "magic cookie" that was used to keep track |
916 | of who called the macro, to help when debugging memory problems. However, |
07fa94a1 |
917 | the current code makes no use of this feature (most Perl developers now |
918 | use run-time memory checkers), so this argument can be any number. |
5f05dabc |
919 | |
920 | The second argument C<pointer> should be the name of a variable that will |
921 | point to the newly allocated memory. |
d1b91892 |
922 | |
d1b91892 |
923 | The third and fourth arguments C<number> and C<type> specify how many of |
924 | the specified type of data structure should be allocated. The argument |
925 | C<type> is passed to C<sizeof>. The final argument to C<Newc>, C<cast>, |
926 | should be used if the C<pointer> argument is different from the C<type> |
927 | argument. |
928 | |
929 | Unlike the C<New> and C<Newc> macros, the C<Newz> macro calls C<memzero> |
930 | to zero out all the newly allocated memory. |
931 | |
932 | Renew(pointer, number, type); |
933 | Renewc(pointer, number, type, cast); |
934 | Safefree(pointer) |
935 | |
936 | These three macros are used to change a memory buffer size or to free a |
937 | piece of memory no longer needed. The arguments to C<Renew> and C<Renewc> |
938 | match those of C<New> and C<Newc> with the exception of not needing the |
939 | "magic cookie" argument. |
940 | |
941 | Move(source, dest, number, type); |
942 | Copy(source, dest, number, type); |
943 | Zero(dest, number, type); |
944 | |
945 | These three macros are used to move, copy, or zero out previously allocated |
946 | memory. The C<source> and C<dest> arguments point to the source and |
947 | destination starting points. Perl will move, copy, or zero out C<number> |
948 | instances of the size of the C<type> data structure (using the C<sizeof> |
949 | function). |
a0d0e21e |
950 | |
5f05dabc |
951 | =head2 PerlIO |
ce3d39e2 |
952 | |
5f05dabc |
953 | The most recent development releases of Perl has been experimenting with |
954 | removing Perl's dependency on the "normal" standard I/O suite and allowing |
955 | other stdio implementations to be used. This involves creating a new |
956 | abstraction layer that then calls whichever implementation of stdio Perl |
68dc0745 |
957 | was compiled with. All XSUBs should now use the functions in the PerlIO |
5f05dabc |
958 | abstraction layer and not make any assumptions about what kind of stdio |
959 | is being used. |
960 | |
961 | For a complete description of the PerlIO abstraction, consult L<perlapio>. |
962 | |
8ebc5c01 |
963 | =head2 Putting a C value on Perl stack |
ce3d39e2 |
964 | |
965 | A lot of opcodes (this is an elementary operation in the internal perl |
966 | stack machine) put an SV* on the stack. However, as an optimization |
967 | the corresponding SV is (usually) not recreated each time. The opcodes |
968 | reuse specially assigned SVs (I<target>s) which are (as a corollary) |
969 | not constantly freed/created. |
970 | |
0a753a76 |
971 | Each of the targets is created only once (but see |
ce3d39e2 |
972 | L<Scratchpads and recursion> below), and when an opcode needs to put |
973 | an integer, a double, or a string on stack, it just sets the |
974 | corresponding parts of its I<target> and puts the I<target> on stack. |
975 | |
976 | The macro to put this target on stack is C<PUSHTARG>, and it is |
977 | directly used in some opcodes, as well as indirectly in zillions of |
978 | others, which use it via C<(X)PUSH[pni]>. |
979 | |
8ebc5c01 |
980 | =head2 Scratchpads |
ce3d39e2 |
981 | |
54310121 |
982 | The question remains on when the SVs which are I<target>s for opcodes |
5f05dabc |
983 | are created. The answer is that they are created when the current unit -- |
984 | a subroutine or a file (for opcodes for statements outside of |
985 | subroutines) -- is compiled. During this time a special anonymous Perl |
ce3d39e2 |
986 | array is created, which is called a scratchpad for the current |
987 | unit. |
988 | |
54310121 |
989 | A scratchpad keeps SVs which are lexicals for the current unit and are |
ce3d39e2 |
990 | targets for opcodes. One can deduce that an SV lives on a scratchpad |
991 | by looking on its flags: lexicals have C<SVs_PADMY> set, and |
992 | I<target>s have C<SVs_PADTMP> set. |
993 | |
54310121 |
994 | The correspondence between OPs and I<target>s is not 1-to-1. Different |
995 | OPs in the compile tree of the unit can use the same target, if this |
ce3d39e2 |
996 | would not conflict with the expected life of the temporary. |
997 | |
2ae324a7 |
998 | =head2 Scratchpads and recursion |
ce3d39e2 |
999 | |
1000 | In fact it is not 100% true that a compiled unit contains a pointer to |
1001 | the scratchpad AV. In fact it contains a pointer to an AV of |
1002 | (initially) one element, and this element is the scratchpad AV. Why do |
1003 | we need an extra level of indirection? |
1004 | |
1005 | The answer is B<recursion>, and maybe (sometime soon) B<threads>. Both |
1006 | these can create several execution pointers going into the same |
1007 | subroutine. For the subroutine-child not write over the temporaries |
1008 | for the subroutine-parent (lifespan of which covers the call to the |
1009 | child), the parent and the child should have different |
1010 | scratchpads. (I<And> the lexicals should be separate anyway!) |
1011 | |
5f05dabc |
1012 | So each subroutine is born with an array of scratchpads (of length 1). |
1013 | On each entry to the subroutine it is checked that the current |
ce3d39e2 |
1014 | depth of the recursion is not more than the length of this array, and |
1015 | if it is, new scratchpad is created and pushed into the array. |
1016 | |
1017 | The I<target>s on this scratchpad are C<undef>s, but they are already |
1018 | marked with correct flags. |
1019 | |
0a753a76 |
1020 | =head1 Compiled code |
1021 | |
1022 | =head2 Code tree |
1023 | |
1024 | Here we describe the internal form your code is converted to by |
1025 | Perl. Start with a simple example: |
1026 | |
1027 | $a = $b + $c; |
1028 | |
1029 | This is converted to a tree similar to this one: |
1030 | |
1031 | assign-to |
1032 | / \ |
1033 | + $a |
1034 | / \ |
1035 | $b $c |
1036 | |
1037 | (but slightly more complicated). This tree reflect the way Perl |
1038 | parsed your code, but has nothing to do with the execution order. |
1039 | There is an additional "thread" going through the nodes of the tree |
1040 | which shows the order of execution of the nodes. In our simplified |
1041 | example above it looks like: |
1042 | |
1043 | $b ---> $c ---> + ---> $a ---> assign-to |
1044 | |
1045 | But with the actual compile tree for C<$a = $b + $c> it is different: |
1046 | some nodes I<optimized away>. As a corollary, though the actual tree |
1047 | contains more nodes than our simplified example, the execution order |
1048 | is the same as in our example. |
1049 | |
1050 | =head2 Examining the tree |
1051 | |
1052 | If you have your perl compiled for debugging (usually done with C<-D |
1053 | optimize=-g> on C<Configure> command line), you may examine the |
1054 | compiled tree by specifying C<-Dx> on the Perl command line. The |
1055 | output takes several lines per node, and for C<$b+$c> it looks like |
1056 | this: |
1057 | |
1058 | 5 TYPE = add ===> 6 |
1059 | TARG = 1 |
1060 | FLAGS = (SCALAR,KIDS) |
1061 | { |
1062 | TYPE = null ===> (4) |
1063 | (was rv2sv) |
1064 | FLAGS = (SCALAR,KIDS) |
1065 | { |
1066 | 3 TYPE = gvsv ===> 4 |
1067 | FLAGS = (SCALAR) |
1068 | GV = main::b |
1069 | } |
1070 | } |
1071 | { |
1072 | TYPE = null ===> (5) |
1073 | (was rv2sv) |
1074 | FLAGS = (SCALAR,KIDS) |
1075 | { |
1076 | 4 TYPE = gvsv ===> 5 |
1077 | FLAGS = (SCALAR) |
1078 | GV = main::c |
1079 | } |
1080 | } |
1081 | |
1082 | This tree has 5 nodes (one per C<TYPE> specifier), only 3 of them are |
1083 | not optimized away (one per number in the left column). The immediate |
1084 | children of the given node correspond to C<{}> pairs on the same level |
1085 | of indentation, thus this listing corresponds to the tree: |
1086 | |
1087 | add |
1088 | / \ |
1089 | null null |
1090 | | | |
1091 | gvsv gvsv |
1092 | |
1093 | The execution order is indicated by C<===E<gt>> marks, thus it is C<3 |
1094 | 4 5 6> (node C<6> is not included into above listing), i.e., |
1095 | C<gvsv gvsv add whatever>. |
1096 | |
1097 | =head2 Compile pass 1: check routines |
1098 | |
1099 | The tree is created by the I<pseudo-compiler> while yacc code feeds it |
1100 | the constructions it recognizes. Since yacc works bottom-up, so does |
1101 | the first pass of perl compilation. |
1102 | |
1103 | What makes this pass interesting for perl developers is that some |
1104 | optimization may be performed on this pass. This is optimization by |
1105 | so-called I<check routines>. The correspondence between node names |
1106 | and corresponding check routines is described in F<opcode.pl> (do not |
1107 | forget to run C<make regen_headers> if you modify this file). |
1108 | |
1109 | A check routine is called when the node is fully constructed except |
1110 | for the execution-order thread. Since at this time there is no |
1111 | back-links to the currently constructed node, one can do most any |
1112 | operation to the top-level node, including freeing it and/or creating |
1113 | new nodes above/below it. |
1114 | |
1115 | The check routine returns the node which should be inserted into the |
1116 | tree (if the top-level node was not modified, check routine returns |
1117 | its argument). |
1118 | |
1119 | By convention, check routines have names C<ck_*>. They are usually |
1120 | called from C<new*OP> subroutines (or C<convert>) (which in turn are |
1121 | called from F<perly.y>). |
1122 | |
1123 | =head2 Compile pass 1a: constant folding |
1124 | |
1125 | Immediately after the check routine is called the returned node is |
1126 | checked for being compile-time executable. If it is (the value is |
1127 | judged to be constant) it is immediately executed, and a I<constant> |
1128 | node with the "return value" of the corresponding subtree is |
1129 | substituted instead. The subtree is deleted. |
1130 | |
1131 | If constant folding was not performed, the execution-order thread is |
1132 | created. |
1133 | |
1134 | =head2 Compile pass 2: context propagation |
1135 | |
1136 | When a context for a part of compile tree is known, it is propagated |
1137 | down through the tree. Aat this time the context can have 5 values |
1138 | (instead of 2 for runtime context): void, boolean, scalar, list, and |
1139 | lvalue. In contrast with the pass 1 this pass is processed from top |
1140 | to bottom: a node's context determines the context for its children. |
1141 | |
1142 | Additional context-dependent optimizations are performed at this time. |
1143 | Since at this moment the compile tree contains back-references (via |
1144 | "thread" pointers), nodes cannot be free()d now. To allow |
1145 | optimized-away nodes at this stage, such nodes are null()ified instead |
1146 | of free()ing (i.e. their type is changed to OP_NULL). |
1147 | |
1148 | =head2 Compile pass 3: peephole optimization |
1149 | |
1150 | After the compile tree for a subroutine (or for an C<eval> or a file) |
1151 | is created, an additional pass over the code is performed. This pass |
1152 | is neither top-down or bottom-up, but in the execution order (with |
1153 | additional compilications for conditionals). These optimizations are |
1154 | done in the subroutine peep(). Optimizations performed at this stage |
1155 | are subject to the same restrictions as in the pass 2. |
1156 | |
1157 | =head1 API LISTING |
a0d0e21e |
1158 | |
cb1a09d0 |
1159 | This is a listing of functions, macros, flags, and variables that may be |
1160 | useful to extension writers or that may be found while reading other |
1161 | extensions. |
a0d0e21e |
1162 | |
cb1a09d0 |
1163 | =over 8 |
a0d0e21e |
1164 | |
cb1a09d0 |
1165 | =item AvFILL |
1166 | |
1167 | See C<av_len>. |
1168 | |
1169 | =item av_clear |
1170 | |
1171 | Clears an array, making it empty. |
1172 | |
1173 | void av_clear _((AV* ar)); |
1174 | |
1175 | =item av_extend |
1176 | |
1177 | Pre-extend an array. The C<key> is the index to which the array should be |
1178 | extended. |
1179 | |
1180 | void av_extend _((AV* ar, I32 key)); |
1181 | |
1182 | =item av_fetch |
1183 | |
1184 | Returns the SV at the specified index in the array. The C<key> is the |
1185 | index. If C<lval> is set then the fetch will be part of a store. Check |
1186 | that the return value is non-null before dereferencing it to a C<SV*>. |
1187 | |
1188 | SV** av_fetch _((AV* ar, I32 key, I32 lval)); |
1189 | |
1190 | =item av_len |
1191 | |
1192 | Returns the highest index in the array. Returns -1 if the array is empty. |
1193 | |
1194 | I32 av_len _((AV* ar)); |
1195 | |
1196 | =item av_make |
1197 | |
5fb8527f |
1198 | Creates a new AV and populates it with a list of SVs. The SVs are copied |
1199 | into the array, so they may be freed after the call to av_make. The new AV |
5f05dabc |
1200 | will have a reference count of 1. |
cb1a09d0 |
1201 | |
1202 | AV* av_make _((I32 size, SV** svp)); |
1203 | |
1204 | =item av_pop |
1205 | |
1206 | Pops an SV off the end of the array. Returns C<&sv_undef> if the array is |
1207 | empty. |
1208 | |
1209 | SV* av_pop _((AV* ar)); |
1210 | |
1211 | =item av_push |
1212 | |
5fb8527f |
1213 | Pushes an SV onto the end of the array. The array will grow automatically |
1214 | to accommodate the addition. |
cb1a09d0 |
1215 | |
1216 | void av_push _((AV* ar, SV* val)); |
1217 | |
1218 | =item av_shift |
1219 | |
1220 | Shifts an SV off the beginning of the array. |
1221 | |
1222 | SV* av_shift _((AV* ar)); |
1223 | |
1224 | =item av_store |
1225 | |
1226 | Stores an SV in an array. The array index is specified as C<key>. The |
1227 | return value will be null if the operation failed, otherwise it can be |
1228 | dereferenced to get the original C<SV*>. |
1229 | |
1230 | SV** av_store _((AV* ar, I32 key, SV* val)); |
1231 | |
1232 | =item av_undef |
1233 | |
1234 | Undefines the array. |
1235 | |
1236 | void av_undef _((AV* ar)); |
1237 | |
1238 | =item av_unshift |
1239 | |
5fb8527f |
1240 | Unshift an SV onto the beginning of the array. The array will grow |
1241 | automatically to accommodate the addition. |
cb1a09d0 |
1242 | |
1243 | void av_unshift _((AV* ar, I32 num)); |
1244 | |
1245 | =item CLASS |
1246 | |
1247 | Variable which is setup by C<xsubpp> to indicate the class name for a C++ XS |
5fb8527f |
1248 | constructor. This is always a C<char*>. See C<THIS> and |
1249 | L<perlxs/"Using XS With C++">. |
cb1a09d0 |
1250 | |
1251 | =item Copy |
1252 | |
1253 | The XSUB-writer's interface to the C C<memcpy> function. The C<s> is the |
1254 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
1255 | the type. |
1256 | |
1257 | (void) Copy( s, d, n, t ); |
1258 | |
1259 | =item croak |
1260 | |
1261 | This is the XSUB-writer's interface to Perl's C<die> function. Use this |
1262 | function the same way you use the C C<printf> function. See C<warn>. |
1263 | |
1264 | =item CvSTASH |
1265 | |
1266 | Returns the stash of the CV. |
1267 | |
1268 | HV * CvSTASH( SV* sv ) |
1269 | |
1270 | =item DBsingle |
1271 | |
1272 | When Perl is run in debugging mode, with the B<-d> switch, this SV is a |
1273 | boolean which indicates whether subs are being single-stepped. |
5fb8527f |
1274 | Single-stepping is automatically turned on after every step. This is the C |
1275 | variable which corresponds to Perl's $DB::single variable. See C<DBsub>. |
cb1a09d0 |
1276 | |
1277 | =item DBsub |
1278 | |
1279 | When Perl is run in debugging mode, with the B<-d> switch, this GV contains |
5fb8527f |
1280 | the SV which holds the name of the sub being debugged. This is the C |
1281 | variable which corresponds to Perl's $DB::sub variable. See C<DBsingle>. |
cb1a09d0 |
1282 | The sub name can be found by |
1283 | |
1284 | SvPV( GvSV( DBsub ), na ) |
1285 | |
5fb8527f |
1286 | =item DBtrace |
1287 | |
1288 | Trace variable used when Perl is run in debugging mode, with the B<-d> |
1289 | switch. This is the C variable which corresponds to Perl's $DB::trace |
1290 | variable. See C<DBsingle>. |
1291 | |
cb1a09d0 |
1292 | =item dMARK |
1293 | |
5fb8527f |
1294 | Declare a stack marker variable, C<mark>, for the XSUB. See C<MARK> and |
1295 | C<dORIGMARK>. |
cb1a09d0 |
1296 | |
1297 | =item dORIGMARK |
1298 | |
1299 | Saves the original stack mark for the XSUB. See C<ORIGMARK>. |
1300 | |
5fb8527f |
1301 | =item dowarn |
1302 | |
1303 | The C variable which corresponds to Perl's $^W warning variable. |
1304 | |
cb1a09d0 |
1305 | =item dSP |
1306 | |
5fb8527f |
1307 | Declares a stack pointer variable, C<sp>, for the XSUB. See C<SP>. |
cb1a09d0 |
1308 | |
1309 | =item dXSARGS |
1310 | |
1311 | Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is |
1312 | usually handled automatically by C<xsubpp>. Declares the C<items> variable |
1313 | to indicate the number of items on the stack. |
1314 | |
5fb8527f |
1315 | =item dXSI32 |
1316 | |
1317 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually |
1318 | handled automatically by C<xsubpp>. |
1319 | |
1320 | =item dXSI32 |
1321 | |
1322 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually |
1323 | handled automatically by C<xsubpp>. |
1324 | |
cb1a09d0 |
1325 | =item ENTER |
1326 | |
1327 | Opening bracket on a callback. See C<LEAVE> and L<perlcall>. |
1328 | |
1329 | ENTER; |
1330 | |
1331 | =item EXTEND |
1332 | |
1333 | Used to extend the argument stack for an XSUB's return values. |
1334 | |
1335 | EXTEND( sp, int x ); |
1336 | |
1337 | =item FREETMPS |
1338 | |
1339 | Closing bracket for temporaries on a callback. See C<SAVETMPS> and |
1340 | L<perlcall>. |
1341 | |
1342 | FREETMPS; |
1343 | |
1344 | =item G_ARRAY |
1345 | |
54310121 |
1346 | Used to indicate array context. See C<GIMME_V>, C<GIMME> and L<perlcall>. |
cb1a09d0 |
1347 | |
1348 | =item G_DISCARD |
1349 | |
1350 | Indicates that arguments returned from a callback should be discarded. See |
1351 | L<perlcall>. |
1352 | |
1353 | =item G_EVAL |
1354 | |
1355 | Used to force a Perl C<eval> wrapper around a callback. See L<perlcall>. |
1356 | |
1357 | =item GIMME |
1358 | |
54310121 |
1359 | A backward-compatible version of C<GIMME_V> which can only return |
1360 | C<G_SCALAR> or C<G_ARRAY>; in a void context, it returns C<G_SCALAR>. |
1361 | |
1362 | =item GIMME_V |
1363 | |
1364 | The XSUB-writer's equivalent to Perl's C<wantarray>. Returns |
1365 | C<G_VOID>, C<G_SCALAR> or C<G_ARRAY> for void, scalar or array |
1366 | context, respectively. |
cb1a09d0 |
1367 | |
1368 | =item G_NOARGS |
1369 | |
1370 | Indicates that no arguments are being sent to a callback. See L<perlcall>. |
1371 | |
1372 | =item G_SCALAR |
1373 | |
54310121 |
1374 | Used to indicate scalar context. See C<GIMME_V>, C<GIMME>, and L<perlcall>. |
1375 | |
1376 | =item G_VOID |
1377 | |
1378 | Used to indicate void context. See C<GIMME_V> and L<perlcall>. |
cb1a09d0 |
1379 | |
faed5253 |
1380 | =item gv_fetchmeth |
1381 | |
1382 | Returns the glob with the given C<name> and a defined subroutine or |
9607fc9c |
1383 | C<NULL>. The glob lives in the given C<stash>, or in the stashes |
1384 | accessable via @ISA and @<UNIVERSAL>. |
faed5253 |
1385 | |
9607fc9c |
1386 | The argument C<level> should be either 0 or -1. If C<level==0>, as a |
0a753a76 |
1387 | side-effect creates a glob with the given C<name> in the given |
1388 | C<stash> which in the case of success contains an alias for the |
1389 | subroutine, and sets up caching info for this glob. Similarly for all |
1390 | the searched stashes. |
1391 | |
9607fc9c |
1392 | This function grants C<"SUPER"> token as a postfix of the stash name. |
1393 | |
0a753a76 |
1394 | The GV returned from C<gv_fetchmeth> may be a method cache entry, |
1395 | which is not visible to Perl code. So when calling C<perl_call_sv>, |
1396 | you should not use the GV directly; instead, you should use the |
1397 | method's CV, which can be obtained from the GV with the C<GvCV> macro. |
faed5253 |
1398 | |
1399 | GV* gv_fetchmeth _((HV* stash, char* name, STRLEN len, I32 level)); |
1400 | |
1401 | =item gv_fetchmethod |
1402 | |
dc848c6f |
1403 | =item gv_fetchmethod_autoload |
1404 | |
faed5253 |
1405 | Returns the glob which contains the subroutine to call to invoke the |
dc848c6f |
1406 | method on the C<stash>. In fact in the presense of autoloading this may |
1407 | be the glob for "AUTOLOAD". In this case the corresponding variable |
faed5253 |
1408 | $AUTOLOAD is already setup. |
1409 | |
dc848c6f |
1410 | The third parameter of C<gv_fetchmethod_autoload> determines whether AUTOLOAD |
1411 | lookup is performed if the given method is not present: non-zero means |
1412 | yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling |
1413 | C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload> with a |
1414 | non-zero C<autoload> parameter. |
1415 | |
1416 | These functions grant C<"SUPER"> token as a prefix of the method name. |
1417 | |
1418 | Note that if you want to keep the returned glob for a long time, you |
1419 | need to check for it being "AUTOLOAD", since at the later time the call |
faed5253 |
1420 | may load a different subroutine due to $AUTOLOAD changing its value. |
1421 | Use the glob created via a side effect to do this. |
1422 | |
dc848c6f |
1423 | These functions have the same side-effects and as C<gv_fetchmeth> with |
1424 | C<level==0>. C<name> should be writable if contains C<':'> or C<'\''>. |
0a753a76 |
1425 | The warning against passing the GV returned by C<gv_fetchmeth> to |
dc848c6f |
1426 | C<perl_call_sv> apply equally to these functions. |
faed5253 |
1427 | |
1428 | GV* gv_fetchmethod _((HV* stash, char* name)); |
dc848c6f |
1429 | GV* gv_fetchmethod_autoload _((HV* stash, char* name, |
1430 | I32 autoload)); |
faed5253 |
1431 | |
cb1a09d0 |
1432 | =item gv_stashpv |
1433 | |
1434 | Returns a pointer to the stash for a specified package. If C<create> is set |
1435 | then the package will be created if it does not already exist. If C<create> |
1436 | is not set and the package does not exist then NULL is returned. |
1437 | |
1438 | HV* gv_stashpv _((char* name, I32 create)); |
1439 | |
1440 | =item gv_stashsv |
1441 | |
1442 | Returns a pointer to the stash for a specified package. See C<gv_stashpv>. |
1443 | |
1444 | HV* gv_stashsv _((SV* sv, I32 create)); |
1445 | |
e5581bf4 |
1446 | =item GvSV |
cb1a09d0 |
1447 | |
e5581bf4 |
1448 | Return the SV from the GV. |
44a8e56a |
1449 | |
1e422769 |
1450 | =item HEf_SVKEY |
1451 | |
1452 | This flag, used in the length slot of hash entries and magic |
1453 | structures, specifies the structure contains a C<SV*> pointer where a |
1454 | C<char*> pointer is to be expected. (For information only--not to be used). |
1455 | |
1e422769 |
1456 | =item HeHASH |
1457 | |
1458 | Returns the computed hash (type C<U32>) stored in the hash entry. |
1459 | |
1460 | HeHASH(HE* he) |
1461 | |
1462 | =item HeKEY |
1463 | |
1464 | Returns the actual pointer stored in the key slot of the hash entry. |
1465 | The pointer may be either C<char*> or C<SV*>, depending on the value of |
1466 | C<HeKLEN()>. Can be assigned to. The C<HePV()> or C<HeSVKEY()> macros |
1467 | are usually preferable for finding the value of a key. |
1468 | |
1469 | HeKEY(HE* he) |
1470 | |
1471 | =item HeKLEN |
1472 | |
1473 | If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry |
1474 | holds an C<SV*> key. Otherwise, holds the actual length of the key. |
1475 | Can be assigned to. The C<HePV()> macro is usually preferable for finding |
1476 | key lengths. |
1477 | |
1478 | HeKLEN(HE* he) |
1479 | |
1480 | =item HePV |
1481 | |
1482 | Returns the key slot of the hash entry as a C<char*> value, doing any |
1483 | necessary dereferencing of possibly C<SV*> keys. The length of |
1484 | the string is placed in C<len> (this is a macro, so do I<not> use |
1485 | C<&len>). If you do not care about what the length of the key is, |
1486 | you may use the global variable C<na>. Remember though, that hash |
1487 | keys in perl are free to contain embedded nulls, so using C<strlen()> |
1488 | or similar is not a good way to find the length of hash keys. |
1489 | This is very similar to the C<SvPV()> macro described elsewhere in |
1490 | this document. |
1491 | |
1492 | HePV(HE* he, STRLEN len) |
1493 | |
1494 | =item HeSVKEY |
1495 | |
1496 | Returns the key as an C<SV*>, or C<Nullsv> if the hash entry |
1497 | does not contain an C<SV*> key. |
1498 | |
1499 | HeSVKEY(HE* he) |
1500 | |
1501 | =item HeSVKEY_force |
1502 | |
1503 | Returns the key as an C<SV*>. Will create and return a temporary |
1504 | mortal C<SV*> if the hash entry contains only a C<char*> key. |
1505 | |
1506 | HeSVKEY_force(HE* he) |
1507 | |
1508 | =item HeSVKEY_set |
1509 | |
1510 | Sets the key to a given C<SV*>, taking care to set the appropriate flags |
1511 | to indicate the presence of an C<SV*> key, and returns the same C<SV*>. |
1512 | |
1513 | HeSVKEY_set(HE* he, SV* sv) |
1514 | |
1515 | =item HeVAL |
1516 | |
1517 | Returns the value slot (type C<SV*>) stored in the hash entry. |
1518 | |
1519 | HeVAL(HE* he) |
1520 | |
cb1a09d0 |
1521 | =item hv_clear |
1522 | |
1523 | Clears a hash, making it empty. |
1524 | |
1525 | void hv_clear _((HV* tb)); |
1526 | |
68dc0745 |
1527 | =item hv_delayfree_ent |
1528 | |
1529 | Releases a hash entry, such as while iterating though the hash, but |
1530 | delays actual freeing of key and value until the end of the current |
1531 | statement (or thereabouts) with C<sv_2mortal>. See C<hv_iternext> |
1532 | and C<hv_free_ent>. |
1533 | |
1534 | void hv_delayfree_ent _((HV* hv, HE* entry)); |
1535 | |
cb1a09d0 |
1536 | =item hv_delete |
1537 | |
1538 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
5fb8527f |
1539 | and returned to the caller. The C<klen> is the length of the key. The |
cb1a09d0 |
1540 | C<flags> value will normally be zero; if set to G_DISCARD then null will be |
1541 | returned. |
1542 | |
1543 | SV* hv_delete _((HV* tb, char* key, U32 klen, I32 flags)); |
1544 | |
1e422769 |
1545 | =item hv_delete_ent |
1546 | |
1547 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
1548 | and returned to the caller. The C<flags> value will normally be zero; if set |
54310121 |
1549 | to G_DISCARD then null will be returned. C<hash> can be a valid precomputed |
1e422769 |
1550 | hash value, or 0 to ask for it to be computed. |
1551 | |
1552 | SV* hv_delete_ent _((HV* tb, SV* key, I32 flags, U32 hash)); |
1553 | |
cb1a09d0 |
1554 | =item hv_exists |
1555 | |
1556 | Returns a boolean indicating whether the specified hash key exists. The |
5fb8527f |
1557 | C<klen> is the length of the key. |
cb1a09d0 |
1558 | |
1559 | bool hv_exists _((HV* tb, char* key, U32 klen)); |
1560 | |
1e422769 |
1561 | =item hv_exists_ent |
1562 | |
1563 | Returns a boolean indicating whether the specified hash key exists. C<hash> |
54310121 |
1564 | can be a valid precomputed hash value, or 0 to ask for it to be computed. |
1e422769 |
1565 | |
1566 | bool hv_exists_ent _((HV* tb, SV* key, U32 hash)); |
1567 | |
cb1a09d0 |
1568 | =item hv_fetch |
1569 | |
1570 | Returns the SV which corresponds to the specified key in the hash. The |
5fb8527f |
1571 | C<klen> is the length of the key. If C<lval> is set then the fetch will be |
cb1a09d0 |
1572 | part of a store. Check that the return value is non-null before |
1573 | dereferencing it to a C<SV*>. |
1574 | |
1575 | SV** hv_fetch _((HV* tb, char* key, U32 klen, I32 lval)); |
1576 | |
1e422769 |
1577 | =item hv_fetch_ent |
1578 | |
1579 | Returns the hash entry which corresponds to the specified key in the hash. |
54310121 |
1580 | C<hash> must be a valid precomputed hash number for the given C<key>, or |
1e422769 |
1581 | 0 if you want the function to compute it. IF C<lval> is set then the |
1582 | fetch will be part of a store. Make sure the return value is non-null |
1583 | before accessing it. The return value when C<tb> is a tied hash |
1584 | is a pointer to a static location, so be sure to make a copy of the |
1585 | structure if you need to store it somewhere. |
1586 | |
1587 | HE* hv_fetch_ent _((HV* tb, SV* key, I32 lval, U32 hash)); |
1588 | |
68dc0745 |
1589 | =item hv_free_ent |
1590 | |
1591 | Releases a hash entry, such as while iterating though the hash. See |
1592 | C<hv_iternext> and C<hv_delayfree_ent>. |
1593 | |
1594 | void hv_free_ent _((HV* hv, HE* entry)); |
1595 | |
cb1a09d0 |
1596 | =item hv_iterinit |
1597 | |
1598 | Prepares a starting point to traverse a hash table. |
1599 | |
1600 | I32 hv_iterinit _((HV* tb)); |
1601 | |
1602 | =item hv_iterkey |
1603 | |
1604 | Returns the key from the current position of the hash iterator. See |
1605 | C<hv_iterinit>. |
1606 | |
1607 | char* hv_iterkey _((HE* entry, I32* retlen)); |
1608 | |
1e422769 |
1609 | =item hv_iterkeysv |
3fe9a6f1 |
1610 | |
1e422769 |
1611 | Returns the key as an C<SV*> from the current position of the hash |
1612 | iterator. The return value will always be a mortal copy of the |
1613 | key. Also see C<hv_iterinit>. |
1614 | |
1615 | SV* hv_iterkeysv _((HE* entry)); |
1616 | |
cb1a09d0 |
1617 | =item hv_iternext |
1618 | |
1619 | Returns entries from a hash iterator. See C<hv_iterinit>. |
1620 | |
1621 | HE* hv_iternext _((HV* tb)); |
1622 | |
1623 | =item hv_iternextsv |
1624 | |
1625 | Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one |
1626 | operation. |
1627 | |
1628 | SV * hv_iternextsv _((HV* hv, char** key, I32* retlen)); |
1629 | |
1630 | =item hv_iterval |
1631 | |
1632 | Returns the value from the current position of the hash iterator. See |
1633 | C<hv_iterkey>. |
1634 | |
1635 | SV* hv_iterval _((HV* tb, HE* entry)); |
1636 | |
1637 | =item hv_magic |
1638 | |
1639 | Adds magic to a hash. See C<sv_magic>. |
1640 | |
1641 | void hv_magic _((HV* hv, GV* gv, int how)); |
1642 | |
1643 | =item HvNAME |
1644 | |
1645 | Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>. |
1646 | |
1647 | char *HvNAME (HV* stash) |
1648 | |
1649 | =item hv_store |
1650 | |
1651 | Stores an SV in a hash. The hash key is specified as C<key> and C<klen> is |
54310121 |
1652 | the length of the key. The C<hash> parameter is the precomputed hash |
cb1a09d0 |
1653 | value; if it is zero then Perl will compute it. The return value will be |
1654 | null if the operation failed, otherwise it can be dereferenced to get the |
1655 | original C<SV*>. |
1656 | |
1657 | SV** hv_store _((HV* tb, char* key, U32 klen, SV* val, U32 hash)); |
1658 | |
1e422769 |
1659 | =item hv_store_ent |
1660 | |
1661 | Stores C<val> in a hash. The hash key is specified as C<key>. The C<hash> |
54310121 |
1662 | parameter is the precomputed hash value; if it is zero then Perl will |
1e422769 |
1663 | compute it. The return value is the new hash entry so created. It will be |
1664 | null if the operation failed or if the entry was stored in a tied hash. |
1665 | Otherwise the contents of the return value can be accessed using the |
1666 | C<He???> macros described here. |
1667 | |
1668 | HE* hv_store_ent _((HV* tb, SV* key, SV* val, U32 hash)); |
1669 | |
cb1a09d0 |
1670 | =item hv_undef |
1671 | |
1672 | Undefines the hash. |
1673 | |
1674 | void hv_undef _((HV* tb)); |
1675 | |
1676 | =item isALNUM |
1677 | |
1678 | Returns a boolean indicating whether the C C<char> is an ascii alphanumeric |
5f05dabc |
1679 | character or digit. |
cb1a09d0 |
1680 | |
1681 | int isALNUM (char c) |
1682 | |
1683 | =item isALPHA |
1684 | |
5fb8527f |
1685 | Returns a boolean indicating whether the C C<char> is an ascii alphabetic |
cb1a09d0 |
1686 | character. |
1687 | |
1688 | int isALPHA (char c) |
1689 | |
1690 | =item isDIGIT |
1691 | |
1692 | Returns a boolean indicating whether the C C<char> is an ascii digit. |
1693 | |
1694 | int isDIGIT (char c) |
1695 | |
1696 | =item isLOWER |
1697 | |
1698 | Returns a boolean indicating whether the C C<char> is a lowercase character. |
1699 | |
1700 | int isLOWER (char c) |
1701 | |
1702 | =item isSPACE |
1703 | |
1704 | Returns a boolean indicating whether the C C<char> is whitespace. |
1705 | |
1706 | int isSPACE (char c) |
1707 | |
1708 | =item isUPPER |
1709 | |
1710 | Returns a boolean indicating whether the C C<char> is an uppercase character. |
1711 | |
1712 | int isUPPER (char c) |
1713 | |
1714 | =item items |
1715 | |
1716 | Variable which is setup by C<xsubpp> to indicate the number of items on the |
5fb8527f |
1717 | stack. See L<perlxs/"Variable-length Parameter Lists">. |
1718 | |
1719 | =item ix |
1720 | |
1721 | Variable which is setup by C<xsubpp> to indicate which of an XSUB's aliases |
1722 | was used to invoke it. See L<perlxs/"The ALIAS: Keyword">. |
cb1a09d0 |
1723 | |
1724 | =item LEAVE |
1725 | |
1726 | Closing bracket on a callback. See C<ENTER> and L<perlcall>. |
1727 | |
1728 | LEAVE; |
1729 | |
1730 | =item MARK |
1731 | |
5fb8527f |
1732 | Stack marker variable for the XSUB. See C<dMARK>. |
cb1a09d0 |
1733 | |
1734 | =item mg_clear |
1735 | |
1736 | Clear something magical that the SV represents. See C<sv_magic>. |
1737 | |
1738 | int mg_clear _((SV* sv)); |
1739 | |
1740 | =item mg_copy |
1741 | |
1742 | Copies the magic from one SV to another. See C<sv_magic>. |
1743 | |
1744 | int mg_copy _((SV *, SV *, char *, STRLEN)); |
1745 | |
1746 | =item mg_find |
1747 | |
1748 | Finds the magic pointer for type matching the SV. See C<sv_magic>. |
1749 | |
1750 | MAGIC* mg_find _((SV* sv, int type)); |
1751 | |
1752 | =item mg_free |
1753 | |
1754 | Free any magic storage used by the SV. See C<sv_magic>. |
1755 | |
1756 | int mg_free _((SV* sv)); |
1757 | |
1758 | =item mg_get |
1759 | |
1760 | Do magic after a value is retrieved from the SV. See C<sv_magic>. |
1761 | |
1762 | int mg_get _((SV* sv)); |
1763 | |
1764 | =item mg_len |
1765 | |
1766 | Report on the SV's length. See C<sv_magic>. |
1767 | |
1768 | U32 mg_len _((SV* sv)); |
1769 | |
1770 | =item mg_magical |
1771 | |
1772 | Turns on the magical status of an SV. See C<sv_magic>. |
1773 | |
1774 | void mg_magical _((SV* sv)); |
1775 | |
1776 | =item mg_set |
1777 | |
1778 | Do magic after a value is assigned to the SV. See C<sv_magic>. |
1779 | |
1780 | int mg_set _((SV* sv)); |
1781 | |
1782 | =item Move |
1783 | |
1784 | The XSUB-writer's interface to the C C<memmove> function. The C<s> is the |
1785 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
1786 | the type. |
1787 | |
1788 | (void) Move( s, d, n, t ); |
1789 | |
1790 | =item na |
1791 | |
1792 | A variable which may be used with C<SvPV> to tell Perl to calculate the |
1793 | string length. |
1794 | |
1795 | =item New |
1796 | |
1797 | The XSUB-writer's interface to the C C<malloc> function. |
1798 | |
1799 | void * New( x, void *ptr, int size, type ) |
1800 | |
1801 | =item Newc |
1802 | |
1803 | The XSUB-writer's interface to the C C<malloc> function, with cast. |
1804 | |
1805 | void * Newc( x, void *ptr, int size, type, cast ) |
1806 | |
1807 | =item Newz |
1808 | |
1809 | The XSUB-writer's interface to the C C<malloc> function. The allocated |
1810 | memory is zeroed with C<memzero>. |
1811 | |
1812 | void * Newz( x, void *ptr, int size, type ) |
1813 | |
1814 | =item newAV |
1815 | |
5f05dabc |
1816 | Creates a new AV. The reference count is set to 1. |
cb1a09d0 |
1817 | |
1818 | AV* newAV _((void)); |
1819 | |
1820 | =item newHV |
1821 | |
5f05dabc |
1822 | Creates a new HV. The reference count is set to 1. |
cb1a09d0 |
1823 | |
1824 | HV* newHV _((void)); |
1825 | |
5f05dabc |
1826 | =item newRV_inc |
cb1a09d0 |
1827 | |
5f05dabc |
1828 | Creates an RV wrapper for an SV. The reference count for the original SV is |
cb1a09d0 |
1829 | incremented. |
1830 | |
5f05dabc |
1831 | SV* newRV_inc _((SV* ref)); |
1832 | |
1833 | For historical reasons, "newRV" is a synonym for "newRV_inc". |
1834 | |
1835 | =item newRV_noinc |
1836 | |
1837 | Creates an RV wrapper for an SV. The reference count for the original |
1838 | SV is B<not> incremented. |
1839 | |
07fa94a1 |
1840 | SV* newRV_noinc _((SV* ref)); |
cb1a09d0 |
1841 | |
1842 | =item newSV |
1843 | |
1844 | Creates a new SV. The C<len> parameter indicates the number of bytes of |
68dc0745 |
1845 | preallocated string space the SV should have. The reference count for the |
07fa94a1 |
1846 | new SV is set to 1. |
cb1a09d0 |
1847 | |
1848 | SV* newSV _((STRLEN len)); |
1849 | |
1850 | =item newSViv |
1851 | |
07fa94a1 |
1852 | Creates a new SV and copies an integer into it. The reference count for the |
1853 | SV is set to 1. |
cb1a09d0 |
1854 | |
1855 | SV* newSViv _((IV i)); |
1856 | |
1857 | =item newSVnv |
1858 | |
07fa94a1 |
1859 | Creates a new SV and copies a double into it. The reference count for the |
1860 | SV is set to 1. |
cb1a09d0 |
1861 | |
1862 | SV* newSVnv _((NV i)); |
1863 | |
1864 | =item newSVpv |
1865 | |
07fa94a1 |
1866 | Creates a new SV and copies a string into it. The reference count for the |
1867 | SV is set to 1. If C<len> is zero then Perl will compute the length. |
cb1a09d0 |
1868 | |
1869 | SV* newSVpv _((char* s, STRLEN len)); |
1870 | |
1871 | =item newSVrv |
1872 | |
1873 | Creates a new SV for the RV, C<rv>, to point to. If C<rv> is not an RV then |
5fb8527f |
1874 | it will be upgraded to one. If C<classname> is non-null then the new SV will |
cb1a09d0 |
1875 | be blessed in the specified package. The new SV is returned and its |
5f05dabc |
1876 | reference count is 1. |
8ebc5c01 |
1877 | |
cb1a09d0 |
1878 | SV* newSVrv _((SV* rv, char* classname)); |
1879 | |
1880 | =item newSVsv |
1881 | |
5fb8527f |
1882 | Creates a new SV which is an exact duplicate of the original SV. |
cb1a09d0 |
1883 | |
1884 | SV* newSVsv _((SV* old)); |
1885 | |
1886 | =item newXS |
1887 | |
1888 | Used by C<xsubpp> to hook up XSUBs as Perl subs. |
1889 | |
1890 | =item newXSproto |
1891 | |
1892 | Used by C<xsubpp> to hook up XSUBs as Perl subs. Adds Perl prototypes to |
1893 | the subs. |
1894 | |
1895 | =item Nullav |
1896 | |
1897 | Null AV pointer. |
1898 | |
1899 | =item Nullch |
1900 | |
1901 | Null character pointer. |
1902 | |
1903 | =item Nullcv |
1904 | |
1905 | Null CV pointer. |
1906 | |
1907 | =item Nullhv |
1908 | |
1909 | Null HV pointer. |
1910 | |
1911 | =item Nullsv |
1912 | |
1913 | Null SV pointer. |
1914 | |
1915 | =item ORIGMARK |
1916 | |
1917 | The original stack mark for the XSUB. See C<dORIGMARK>. |
1918 | |
1919 | =item perl_alloc |
1920 | |
1921 | Allocates a new Perl interpreter. See L<perlembed>. |
1922 | |
1923 | =item perl_call_argv |
1924 | |
1925 | Performs a callback to the specified Perl sub. See L<perlcall>. |
1926 | |
1927 | I32 perl_call_argv _((char* subname, I32 flags, char** argv)); |
1928 | |
1929 | =item perl_call_method |
1930 | |
1931 | Performs a callback to the specified Perl method. The blessed object must |
1932 | be on the stack. See L<perlcall>. |
1933 | |
1934 | I32 perl_call_method _((char* methname, I32 flags)); |
1935 | |
1936 | =item perl_call_pv |
1937 | |
1938 | Performs a callback to the specified Perl sub. See L<perlcall>. |
1939 | |
1940 | I32 perl_call_pv _((char* subname, I32 flags)); |
1941 | |
1942 | =item perl_call_sv |
1943 | |
1944 | Performs a callback to the Perl sub whose name is in the SV. See |
1945 | L<perlcall>. |
1946 | |
1947 | I32 perl_call_sv _((SV* sv, I32 flags)); |
1948 | |
1949 | =item perl_construct |
1950 | |
1951 | Initializes a new Perl interpreter. See L<perlembed>. |
1952 | |
1953 | =item perl_destruct |
1954 | |
1955 | Shuts down a Perl interpreter. See L<perlembed>. |
1956 | |
1957 | =item perl_eval_sv |
1958 | |
1959 | Tells Perl to C<eval> the string in the SV. |
1960 | |
1961 | I32 perl_eval_sv _((SV* sv, I32 flags)); |
1962 | |
1963 | =item perl_free |
1964 | |
1965 | Releases a Perl interpreter. See L<perlembed>. |
1966 | |
1967 | =item perl_get_av |
1968 | |
1969 | Returns the AV of the specified Perl array. If C<create> is set and the |
1970 | Perl variable does not exist then it will be created. If C<create> is not |
1971 | set and the variable does not exist then null is returned. |
1972 | |
1973 | AV* perl_get_av _((char* name, I32 create)); |
1974 | |
1975 | =item perl_get_cv |
1976 | |
1977 | Returns the CV of the specified Perl sub. If C<create> is set and the Perl |
1978 | variable does not exist then it will be created. If C<create> is not |
1979 | set and the variable does not exist then null is returned. |
1980 | |
1981 | CV* perl_get_cv _((char* name, I32 create)); |
1982 | |
1983 | =item perl_get_hv |
1984 | |
1985 | Returns the HV of the specified Perl hash. If C<create> is set and the Perl |
1986 | variable does not exist then it will be created. If C<create> is not |
1987 | set and the variable does not exist then null is returned. |
1988 | |
1989 | HV* perl_get_hv _((char* name, I32 create)); |
1990 | |
1991 | =item perl_get_sv |
1992 | |
1993 | Returns the SV of the specified Perl scalar. If C<create> is set and the |
1994 | Perl variable does not exist then it will be created. If C<create> is not |
1995 | set and the variable does not exist then null is returned. |
1996 | |
1997 | SV* perl_get_sv _((char* name, I32 create)); |
1998 | |
1999 | =item perl_parse |
2000 | |
2001 | Tells a Perl interpreter to parse a Perl script. See L<perlembed>. |
2002 | |
2003 | =item perl_require_pv |
2004 | |
2005 | Tells Perl to C<require> a module. |
2006 | |
2007 | void perl_require_pv _((char* pv)); |
2008 | |
2009 | =item perl_run |
2010 | |
2011 | Tells a Perl interpreter to run. See L<perlembed>. |
2012 | |
2013 | =item POPi |
2014 | |
2015 | Pops an integer off the stack. |
2016 | |
2017 | int POPi(); |
2018 | |
2019 | =item POPl |
2020 | |
2021 | Pops a long off the stack. |
2022 | |
2023 | long POPl(); |
2024 | |
2025 | =item POPp |
2026 | |
2027 | Pops a string off the stack. |
2028 | |
2029 | char * POPp(); |
2030 | |
2031 | =item POPn |
2032 | |
2033 | Pops a double off the stack. |
2034 | |
2035 | double POPn(); |
2036 | |
2037 | =item POPs |
2038 | |
2039 | Pops an SV off the stack. |
2040 | |
2041 | SV* POPs(); |
2042 | |
2043 | =item PUSHMARK |
2044 | |
2045 | Opening bracket for arguments on a callback. See C<PUTBACK> and L<perlcall>. |
2046 | |
2047 | PUSHMARK(p) |
2048 | |
2049 | =item PUSHi |
2050 | |
2051 | Push an integer onto the stack. The stack must have room for this element. |
2052 | See C<XPUSHi>. |
2053 | |
2054 | PUSHi(int d) |
2055 | |
2056 | =item PUSHn |
2057 | |
2058 | Push a double onto the stack. The stack must have room for this element. |
2059 | See C<XPUSHn>. |
2060 | |
2061 | PUSHn(double d) |
2062 | |
2063 | =item PUSHp |
2064 | |
2065 | Push a string onto the stack. The stack must have room for this element. |
2066 | The C<len> indicates the length of the string. See C<XPUSHp>. |
2067 | |
2068 | PUSHp(char *c, int len ) |
2069 | |
2070 | =item PUSHs |
2071 | |
2072 | Push an SV onto the stack. The stack must have room for this element. See |
2073 | C<XPUSHs>. |
2074 | |
2075 | PUSHs(sv) |
2076 | |
2077 | =item PUTBACK |
2078 | |
2079 | Closing bracket for XSUB arguments. This is usually handled by C<xsubpp>. |
2080 | See C<PUSHMARK> and L<perlcall> for other uses. |
2081 | |
2082 | PUTBACK; |
2083 | |
2084 | =item Renew |
2085 | |
2086 | The XSUB-writer's interface to the C C<realloc> function. |
2087 | |
2088 | void * Renew( void *ptr, int size, type ) |
2089 | |
2090 | =item Renewc |
2091 | |
2092 | The XSUB-writer's interface to the C C<realloc> function, with cast. |
2093 | |
2094 | void * Renewc( void *ptr, int size, type, cast ) |
2095 | |
2096 | =item RETVAL |
2097 | |
2098 | Variable which is setup by C<xsubpp> to hold the return value for an XSUB. |
5fb8527f |
2099 | This is always the proper type for the XSUB. |
2100 | See L<perlxs/"The RETVAL Variable">. |
cb1a09d0 |
2101 | |
2102 | =item safefree |
2103 | |
2104 | The XSUB-writer's interface to the C C<free> function. |
2105 | |
2106 | =item safemalloc |
2107 | |
2108 | The XSUB-writer's interface to the C C<malloc> function. |
2109 | |
2110 | =item saferealloc |
2111 | |
2112 | The XSUB-writer's interface to the C C<realloc> function. |
2113 | |
2114 | =item savepv |
2115 | |
2116 | Copy a string to a safe spot. This does not use an SV. |
2117 | |
2118 | char* savepv _((char* sv)); |
2119 | |
2120 | =item savepvn |
2121 | |
2122 | Copy a string to a safe spot. The C<len> indicates number of bytes to |
2123 | copy. This does not use an SV. |
2124 | |
2125 | char* savepvn _((char* sv, I32 len)); |
2126 | |
2127 | =item SAVETMPS |
2128 | |
2129 | Opening bracket for temporaries on a callback. See C<FREETMPS> and |
2130 | L<perlcall>. |
2131 | |
2132 | SAVETMPS; |
2133 | |
2134 | =item SP |
2135 | |
2136 | Stack pointer. This is usually handled by C<xsubpp>. See C<dSP> and |
2137 | C<SPAGAIN>. |
2138 | |
2139 | =item SPAGAIN |
2140 | |
54310121 |
2141 | Refetch the stack pointer. Used after a callback. See L<perlcall>. |
cb1a09d0 |
2142 | |
2143 | SPAGAIN; |
2144 | |
2145 | =item ST |
2146 | |
2147 | Used to access elements on the XSUB's stack. |
2148 | |
2149 | SV* ST(int x) |
2150 | |
2151 | =item strEQ |
2152 | |
2153 | Test two strings to see if they are equal. Returns true or false. |
2154 | |
2155 | int strEQ( char *s1, char *s2 ) |
2156 | |
2157 | =item strGE |
2158 | |
2159 | Test two strings to see if the first, C<s1>, is greater than or equal to the |
2160 | second, C<s2>. Returns true or false. |
2161 | |
2162 | int strGE( char *s1, char *s2 ) |
2163 | |
2164 | =item strGT |
2165 | |
2166 | Test two strings to see if the first, C<s1>, is greater than the second, |
2167 | C<s2>. Returns true or false. |
2168 | |
2169 | int strGT( char *s1, char *s2 ) |
2170 | |
2171 | =item strLE |
2172 | |
2173 | Test two strings to see if the first, C<s1>, is less than or equal to the |
2174 | second, C<s2>. Returns true or false. |
2175 | |
2176 | int strLE( char *s1, char *s2 ) |
2177 | |
2178 | =item strLT |
2179 | |
2180 | Test two strings to see if the first, C<s1>, is less than the second, |
2181 | C<s2>. Returns true or false. |
2182 | |
2183 | int strLT( char *s1, char *s2 ) |
2184 | |
2185 | =item strNE |
2186 | |
2187 | Test two strings to see if they are different. Returns true or false. |
2188 | |
2189 | int strNE( char *s1, char *s2 ) |
2190 | |
2191 | =item strnEQ |
2192 | |
2193 | Test two strings to see if they are equal. The C<len> parameter indicates |
2194 | the number of bytes to compare. Returns true or false. |
2195 | |
2196 | int strnEQ( char *s1, char *s2 ) |
2197 | |
2198 | =item strnNE |
2199 | |
2200 | Test two strings to see if they are different. The C<len> parameter |
2201 | indicates the number of bytes to compare. Returns true or false. |
2202 | |
2203 | int strnNE( char *s1, char *s2, int len ) |
2204 | |
2205 | =item sv_2mortal |
2206 | |
2207 | Marks an SV as mortal. The SV will be destroyed when the current context |
2208 | ends. |
2209 | |
2210 | SV* sv_2mortal _((SV* sv)); |
2211 | |
2212 | =item sv_bless |
2213 | |
2214 | Blesses an SV into a specified package. The SV must be an RV. The package |
07fa94a1 |
2215 | must be designated by its stash (see C<gv_stashpv()>). The reference count |
2216 | of the SV is unaffected. |
cb1a09d0 |
2217 | |
2218 | SV* sv_bless _((SV* sv, HV* stash)); |
2219 | |
2220 | =item sv_catpv |
2221 | |
2222 | Concatenates the string onto the end of the string which is in the SV. |
2223 | |
2224 | void sv_catpv _((SV* sv, char* ptr)); |
2225 | |
2226 | =item sv_catpvn |
2227 | |
2228 | Concatenates the string onto the end of the string which is in the SV. The |
2229 | C<len> indicates number of bytes to copy. |
2230 | |
2231 | void sv_catpvn _((SV* sv, char* ptr, STRLEN len)); |
2232 | |
2233 | =item sv_catsv |
2234 | |
5fb8527f |
2235 | Concatenates the string from SV C<ssv> onto the end of the string in SV |
cb1a09d0 |
2236 | C<dsv>. |
2237 | |
2238 | void sv_catsv _((SV* dsv, SV* ssv)); |
2239 | |
5fb8527f |
2240 | =item sv_cmp |
2241 | |
2242 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the |
2243 | string in C<sv1> is less than, equal to, or greater than the string in |
2244 | C<sv2>. |
2245 | |
2246 | I32 sv_cmp _((SV* sv1, SV* sv2)); |
2247 | |
2248 | =item sv_cmp |
2249 | |
2250 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the |
2251 | string in C<sv1> is less than, equal to, or greater than the string in |
2252 | C<sv2>. |
2253 | |
2254 | I32 sv_cmp _((SV* sv1, SV* sv2)); |
2255 | |
cb1a09d0 |
2256 | =item SvCUR |
2257 | |
2258 | Returns the length of the string which is in the SV. See C<SvLEN>. |
2259 | |
2260 | int SvCUR (SV* sv) |
2261 | |
2262 | =item SvCUR_set |
2263 | |
2264 | Set the length of the string which is in the SV. See C<SvCUR>. |
2265 | |
2266 | SvCUR_set (SV* sv, int val ) |
2267 | |
5fb8527f |
2268 | =item sv_dec |
2269 | |
5f05dabc |
2270 | Auto-decrement of the value in the SV. |
5fb8527f |
2271 | |
2272 | void sv_dec _((SV* sv)); |
2273 | |
2274 | =item sv_dec |
2275 | |
5f05dabc |
2276 | Auto-decrement of the value in the SV. |
5fb8527f |
2277 | |
2278 | void sv_dec _((SV* sv)); |
2279 | |
cb1a09d0 |
2280 | =item SvEND |
2281 | |
2282 | Returns a pointer to the last character in the string which is in the SV. |
2283 | See C<SvCUR>. Access the character as |
2284 | |
2285 | *SvEND(sv) |
2286 | |
5fb8527f |
2287 | =item sv_eq |
2288 | |
2289 | Returns a boolean indicating whether the strings in the two SVs are |
2290 | identical. |
2291 | |
2292 | I32 sv_eq _((SV* sv1, SV* sv2)); |
2293 | |
cb1a09d0 |
2294 | =item SvGROW |
2295 | |
5fb8527f |
2296 | Expands the character buffer in the SV. Calls C<sv_grow> to perform the |
2297 | expansion if necessary. Returns a pointer to the character buffer. |
cb1a09d0 |
2298 | |
2299 | char * SvGROW( SV* sv, int len ) |
2300 | |
5fb8527f |
2301 | =item sv_grow |
2302 | |
2303 | Expands the character buffer in the SV. This will use C<sv_unref> and will |
2304 | upgrade the SV to C<SVt_PV>. Returns a pointer to the character buffer. |
2305 | Use C<SvGROW>. |
2306 | |
2307 | =item sv_inc |
2308 | |
07fa94a1 |
2309 | Auto-increment of the value in the SV. |
5fb8527f |
2310 | |
2311 | void sv_inc _((SV* sv)); |
2312 | |
cb1a09d0 |
2313 | =item SvIOK |
2314 | |
2315 | Returns a boolean indicating whether the SV contains an integer. |
2316 | |
2317 | int SvIOK (SV* SV) |
2318 | |
2319 | =item SvIOK_off |
2320 | |
2321 | Unsets the IV status of an SV. |
2322 | |
2323 | SvIOK_off (SV* sv) |
2324 | |
2325 | =item SvIOK_on |
2326 | |
2327 | Tells an SV that it is an integer. |
2328 | |
2329 | SvIOK_on (SV* sv) |
2330 | |
5fb8527f |
2331 | =item SvIOK_only |
2332 | |
2333 | Tells an SV that it is an integer and disables all other OK bits. |
2334 | |
2335 | SvIOK_on (SV* sv) |
2336 | |
2337 | =item SvIOK_only |
2338 | |
2339 | Tells an SV that it is an integer and disables all other OK bits. |
2340 | |
2341 | SvIOK_on (SV* sv) |
2342 | |
cb1a09d0 |
2343 | =item SvIOKp |
2344 | |
2345 | Returns a boolean indicating whether the SV contains an integer. Checks the |
2346 | B<private> setting. Use C<SvIOK>. |
2347 | |
2348 | int SvIOKp (SV* SV) |
2349 | |
2350 | =item sv_isa |
2351 | |
2352 | Returns a boolean indicating whether the SV is blessed into the specified |
2353 | class. This does not know how to check for subtype, so it doesn't work in |
2354 | an inheritance relationship. |
2355 | |
2356 | int sv_isa _((SV* sv, char* name)); |
2357 | |
2358 | =item SvIV |
2359 | |
2360 | Returns the integer which is in the SV. |
2361 | |
2362 | int SvIV (SV* sv) |
2363 | |
2364 | =item sv_isobject |
2365 | |
2366 | Returns a boolean indicating whether the SV is an RV pointing to a blessed |
2367 | object. If the SV is not an RV, or if the object is not blessed, then this |
2368 | will return false. |
2369 | |
2370 | int sv_isobject _((SV* sv)); |
2371 | |
2372 | =item SvIVX |
2373 | |
2374 | Returns the integer which is stored in the SV. |
2375 | |
2376 | int SvIVX (SV* sv); |
2377 | |
2378 | =item SvLEN |
2379 | |
2380 | Returns the size of the string buffer in the SV. See C<SvCUR>. |
2381 | |
2382 | int SvLEN (SV* sv) |
2383 | |
5fb8527f |
2384 | =item sv_len |
2385 | |
2386 | Returns the length of the string in the SV. Use C<SvCUR>. |
2387 | |
2388 | STRLEN sv_len _((SV* sv)); |
2389 | |
2390 | =item sv_len |
2391 | |
2392 | Returns the length of the string in the SV. Use C<SvCUR>. |
2393 | |
2394 | STRLEN sv_len _((SV* sv)); |
2395 | |
cb1a09d0 |
2396 | =item sv_magic |
2397 | |
2398 | Adds magic to an SV. |
2399 | |
2400 | void sv_magic _((SV* sv, SV* obj, int how, char* name, I32 namlen)); |
2401 | |
2402 | =item sv_mortalcopy |
2403 | |
2404 | Creates a new SV which is a copy of the original SV. The new SV is marked |
5f05dabc |
2405 | as mortal. |
cb1a09d0 |
2406 | |
2407 | SV* sv_mortalcopy _((SV* oldsv)); |
2408 | |
2409 | =item SvOK |
2410 | |
2411 | Returns a boolean indicating whether the value is an SV. |
2412 | |
2413 | int SvOK (SV* sv) |
2414 | |
2415 | =item sv_newmortal |
2416 | |
5f05dabc |
2417 | Creates a new SV which is mortal. The reference count of the SV is set to 1. |
cb1a09d0 |
2418 | |
2419 | SV* sv_newmortal _((void)); |
2420 | |
2421 | =item sv_no |
2422 | |
2423 | This is the C<false> SV. See C<sv_yes>. Always refer to this as C<&sv_no>. |
2424 | |
2425 | =item SvNIOK |
2426 | |
2427 | Returns a boolean indicating whether the SV contains a number, integer or |
2428 | double. |
2429 | |
2430 | int SvNIOK (SV* SV) |
2431 | |
2432 | =item SvNIOK_off |
2433 | |
2434 | Unsets the NV/IV status of an SV. |
2435 | |
2436 | SvNIOK_off (SV* sv) |
2437 | |
2438 | =item SvNIOKp |
2439 | |
2440 | Returns a boolean indicating whether the SV contains a number, integer or |
2441 | double. Checks the B<private> setting. Use C<SvNIOK>. |
2442 | |
2443 | int SvNIOKp (SV* SV) |
2444 | |
2445 | =item SvNOK |
2446 | |
2447 | Returns a boolean indicating whether the SV contains a double. |
2448 | |
2449 | int SvNOK (SV* SV) |
2450 | |
2451 | =item SvNOK_off |
2452 | |
2453 | Unsets the NV status of an SV. |
2454 | |
2455 | SvNOK_off (SV* sv) |
2456 | |
2457 | =item SvNOK_on |
2458 | |
2459 | Tells an SV that it is a double. |
2460 | |
2461 | SvNOK_on (SV* sv) |
2462 | |
5fb8527f |
2463 | =item SvNOK_only |
2464 | |
2465 | Tells an SV that it is a double and disables all other OK bits. |
2466 | |
2467 | SvNOK_on (SV* sv) |
2468 | |
2469 | =item SvNOK_only |
2470 | |
2471 | Tells an SV that it is a double and disables all other OK bits. |
2472 | |
2473 | SvNOK_on (SV* sv) |
2474 | |
cb1a09d0 |
2475 | =item SvNOKp |
2476 | |
2477 | Returns a boolean indicating whether the SV contains a double. Checks the |
2478 | B<private> setting. Use C<SvNOK>. |
2479 | |
2480 | int SvNOKp (SV* SV) |
2481 | |
2482 | =item SvNV |
2483 | |
2484 | Returns the double which is stored in the SV. |
2485 | |
2486 | double SvNV (SV* sv); |
2487 | |
2488 | =item SvNVX |
2489 | |
2490 | Returns the double which is stored in the SV. |
2491 | |
2492 | double SvNVX (SV* sv); |
2493 | |
2494 | =item SvPOK |
2495 | |
2496 | Returns a boolean indicating whether the SV contains a character string. |
2497 | |
2498 | int SvPOK (SV* SV) |
2499 | |
2500 | =item SvPOK_off |
2501 | |
2502 | Unsets the PV status of an SV. |
2503 | |
2504 | SvPOK_off (SV* sv) |
2505 | |
2506 | =item SvPOK_on |
2507 | |
2508 | Tells an SV that it is a string. |
2509 | |
2510 | SvPOK_on (SV* sv) |
2511 | |
5fb8527f |
2512 | =item SvPOK_only |
2513 | |
2514 | Tells an SV that it is a string and disables all other OK bits. |
2515 | |
2516 | SvPOK_on (SV* sv) |
2517 | |
2518 | =item SvPOK_only |
2519 | |
2520 | Tells an SV that it is a string and disables all other OK bits. |
2521 | |
2522 | SvPOK_on (SV* sv) |
2523 | |
cb1a09d0 |
2524 | =item SvPOKp |
2525 | |
2526 | Returns a boolean indicating whether the SV contains a character string. |
2527 | Checks the B<private> setting. Use C<SvPOK>. |
2528 | |
2529 | int SvPOKp (SV* SV) |
2530 | |
2531 | =item SvPV |
2532 | |
2533 | Returns a pointer to the string in the SV, or a stringified form of the SV |
2534 | if the SV does not contain a string. If C<len> is C<na> then Perl will |
2535 | handle the length on its own. |
2536 | |
2537 | char * SvPV (SV* sv, int len ) |
2538 | |
2539 | =item SvPVX |
2540 | |
2541 | Returns a pointer to the string in the SV. The SV must contain a string. |
2542 | |
2543 | char * SvPVX (SV* sv) |
2544 | |
2545 | =item SvREFCNT |
2546 | |
5f05dabc |
2547 | Returns the value of the object's reference count. |
cb1a09d0 |
2548 | |
2549 | int SvREFCNT (SV* sv); |
2550 | |
2551 | =item SvREFCNT_dec |
2552 | |
5f05dabc |
2553 | Decrements the reference count of the given SV. |
cb1a09d0 |
2554 | |
2555 | void SvREFCNT_dec (SV* sv) |
2556 | |
2557 | =item SvREFCNT_inc |
2558 | |
5f05dabc |
2559 | Increments the reference count of the given SV. |
cb1a09d0 |
2560 | |
2561 | void SvREFCNT_inc (SV* sv) |
2562 | |
2563 | =item SvROK |
2564 | |
2565 | Tests if the SV is an RV. |
2566 | |
2567 | int SvROK (SV* sv) |
2568 | |
2569 | =item SvROK_off |
2570 | |
2571 | Unsets the RV status of an SV. |
2572 | |
2573 | SvROK_off (SV* sv) |
2574 | |
2575 | =item SvROK_on |
2576 | |
2577 | Tells an SV that it is an RV. |
2578 | |
2579 | SvROK_on (SV* sv) |
2580 | |
2581 | =item SvRV |
2582 | |
2583 | Dereferences an RV to return the SV. |
2584 | |
2585 | SV* SvRV (SV* sv); |
2586 | |
2587 | =item sv_setiv |
2588 | |
2589 | Copies an integer into the given SV. |
2590 | |
2591 | void sv_setiv _((SV* sv, IV num)); |
2592 | |
2593 | =item sv_setnv |
2594 | |
2595 | Copies a double into the given SV. |
2596 | |
2597 | void sv_setnv _((SV* sv, double num)); |
2598 | |
2599 | =item sv_setpv |
2600 | |
2601 | Copies a string into an SV. The string must be null-terminated. |
2602 | |
2603 | void sv_setpv _((SV* sv, char* ptr)); |
2604 | |
2605 | =item sv_setpvn |
2606 | |
2607 | Copies a string into an SV. The C<len> parameter indicates the number of |
2608 | bytes to be copied. |
2609 | |
2610 | void sv_setpvn _((SV* sv, char* ptr, STRLEN len)); |
2611 | |
2612 | =item sv_setref_iv |
2613 | |
5fb8527f |
2614 | Copies an integer into a new SV, optionally blessing the SV. The C<rv> |
2615 | argument will be upgraded to an RV. That RV will be modified to point to |
2616 | the new SV. The C<classname> argument indicates the package for the |
2617 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
2618 | will be returned and will have a reference count of 1. |
cb1a09d0 |
2619 | |
2620 | SV* sv_setref_iv _((SV *rv, char *classname, IV iv)); |
2621 | |
2622 | =item sv_setref_nv |
2623 | |
5fb8527f |
2624 | Copies a double into a new SV, optionally blessing the SV. The C<rv> |
2625 | argument will be upgraded to an RV. That RV will be modified to point to |
2626 | the new SV. The C<classname> argument indicates the package for the |
2627 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
2628 | will be returned and will have a reference count of 1. |
cb1a09d0 |
2629 | |
2630 | SV* sv_setref_nv _((SV *rv, char *classname, double nv)); |
2631 | |
2632 | =item sv_setref_pv |
2633 | |
5fb8527f |
2634 | Copies a pointer into a new SV, optionally blessing the SV. The C<rv> |
2635 | argument will be upgraded to an RV. That RV will be modified to point to |
2636 | the new SV. If the C<pv> argument is NULL then C<sv_undef> will be placed |
2637 | into the SV. The C<classname> argument indicates the package for the |
2638 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
2639 | will be returned and will have a reference count of 1. |
cb1a09d0 |
2640 | |
2641 | SV* sv_setref_pv _((SV *rv, char *classname, void* pv)); |
2642 | |
2643 | Do not use with integral Perl types such as HV, AV, SV, CV, because those |
2644 | objects will become corrupted by the pointer copy process. |
2645 | |
2646 | Note that C<sv_setref_pvn> copies the string while this copies the pointer. |
2647 | |
2648 | =item sv_setref_pvn |
2649 | |
5fb8527f |
2650 | Copies a string into a new SV, optionally blessing the SV. The length of the |
2651 | string must be specified with C<n>. The C<rv> argument will be upgraded to |
2652 | an RV. That RV will be modified to point to the new SV. The C<classname> |
cb1a09d0 |
2653 | argument indicates the package for the blessing. Set C<classname> to |
2654 | C<Nullch> to avoid the blessing. The new SV will be returned and will have |
5f05dabc |
2655 | a reference count of 1. |
cb1a09d0 |
2656 | |
2657 | SV* sv_setref_pvn _((SV *rv, char *classname, char* pv, I32 n)); |
2658 | |
2659 | Note that C<sv_setref_pv> copies the pointer while this copies the string. |
2660 | |
2661 | =item sv_setsv |
2662 | |
2663 | Copies the contents of the source SV C<ssv> into the destination SV C<dsv>. |
5f05dabc |
2664 | The source SV may be destroyed if it is mortal. |
cb1a09d0 |
2665 | |
2666 | void sv_setsv _((SV* dsv, SV* ssv)); |
2667 | |
2668 | =item SvSTASH |
2669 | |
2670 | Returns the stash of the SV. |
2671 | |
2672 | HV * SvSTASH (SV* sv) |
2673 | |
2674 | =item SVt_IV |
2675 | |
2676 | Integer type flag for scalars. See C<svtype>. |
2677 | |
2678 | =item SVt_PV |
2679 | |
2680 | Pointer type flag for scalars. See C<svtype>. |
2681 | |
2682 | =item SVt_PVAV |
2683 | |
2684 | Type flag for arrays. See C<svtype>. |
2685 | |
2686 | =item SVt_PVCV |
2687 | |
2688 | Type flag for code refs. See C<svtype>. |
2689 | |
2690 | =item SVt_PVHV |
2691 | |
2692 | Type flag for hashes. See C<svtype>. |
2693 | |
2694 | =item SVt_PVMG |
2695 | |
2696 | Type flag for blessed scalars. See C<svtype>. |
2697 | |
2698 | =item SVt_NV |
2699 | |
2700 | Double type flag for scalars. See C<svtype>. |
2701 | |
2702 | =item SvTRUE |
2703 | |
2704 | Returns a boolean indicating whether Perl would evaluate the SV as true or |
2705 | false, defined or undefined. |
2706 | |
2707 | int SvTRUE (SV* sv) |
2708 | |
2709 | =item SvTYPE |
2710 | |
2711 | Returns the type of the SV. See C<svtype>. |
2712 | |
2713 | svtype SvTYPE (SV* sv) |
2714 | |
2715 | =item svtype |
2716 | |
2717 | An enum of flags for Perl types. These are found in the file B<sv.h> in the |
2718 | C<svtype> enum. Test these flags with the C<SvTYPE> macro. |
2719 | |
2720 | =item SvUPGRADE |
2721 | |
5fb8527f |
2722 | Used to upgrade an SV to a more complex form. Uses C<sv_upgrade> to perform |
2723 | the upgrade if necessary. See C<svtype>. |
2724 | |
2725 | bool SvUPGRADE _((SV* sv, svtype mt)); |
2726 | |
2727 | =item sv_upgrade |
2728 | |
2729 | Upgrade an SV to a more complex form. Use C<SvUPGRADE>. See C<svtype>. |
cb1a09d0 |
2730 | |
2731 | =item sv_undef |
2732 | |
2733 | This is the C<undef> SV. Always refer to this as C<&sv_undef>. |
2734 | |
5fb8527f |
2735 | =item sv_unref |
2736 | |
07fa94a1 |
2737 | Unsets the RV status of the SV, and decrements the reference count of |
2738 | whatever was being referenced by the RV. This can almost be thought of |
2739 | as a reversal of C<newSVrv>. See C<SvROK_off>. |
5fb8527f |
2740 | |
2741 | void sv_unref _((SV* sv)); |
2742 | |
cb1a09d0 |
2743 | =item sv_usepvn |
2744 | |
2745 | Tells an SV to use C<ptr> to find its string value. Normally the string is |
5fb8527f |
2746 | stored inside the SV but sv_usepvn allows the SV to use an outside string. |
2747 | The C<ptr> should point to memory that was allocated by C<malloc>. The |
cb1a09d0 |
2748 | string length, C<len>, must be supplied. This function will realloc the |
2749 | memory pointed to by C<ptr>, so that pointer should not be freed or used by |
2750 | the programmer after giving it to sv_usepvn. |
2751 | |
2752 | void sv_usepvn _((SV* sv, char* ptr, STRLEN len)); |
2753 | |
2754 | =item sv_yes |
2755 | |
2756 | This is the C<true> SV. See C<sv_no>. Always refer to this as C<&sv_yes>. |
2757 | |
2758 | =item THIS |
2759 | |
2760 | Variable which is setup by C<xsubpp> to designate the object in a C++ XSUB. |
2761 | This is always the proper type for the C++ object. See C<CLASS> and |
5fb8527f |
2762 | L<perlxs/"Using XS With C++">. |
cb1a09d0 |
2763 | |
2764 | =item toLOWER |
2765 | |
2766 | Converts the specified character to lowercase. |
2767 | |
2768 | int toLOWER (char c) |
2769 | |
2770 | =item toUPPER |
2771 | |
2772 | Converts the specified character to uppercase. |
2773 | |
2774 | int toUPPER (char c) |
2775 | |
2776 | =item warn |
2777 | |
2778 | This is the XSUB-writer's interface to Perl's C<warn> function. Use this |
2779 | function the same way you use the C C<printf> function. See C<croak()>. |
2780 | |
2781 | =item XPUSHi |
2782 | |
2783 | Push an integer onto the stack, extending the stack if necessary. See |
2784 | C<PUSHi>. |
2785 | |
2786 | XPUSHi(int d) |
2787 | |
2788 | =item XPUSHn |
2789 | |
2790 | Push a double onto the stack, extending the stack if necessary. See |
2791 | C<PUSHn>. |
2792 | |
2793 | XPUSHn(double d) |
2794 | |
2795 | =item XPUSHp |
2796 | |
2797 | Push a string onto the stack, extending the stack if necessary. The C<len> |
2798 | indicates the length of the string. See C<PUSHp>. |
2799 | |
2800 | XPUSHp(char *c, int len) |
2801 | |
2802 | =item XPUSHs |
2803 | |
2804 | Push an SV onto the stack, extending the stack if necessary. See C<PUSHs>. |
2805 | |
2806 | XPUSHs(sv) |
2807 | |
5fb8527f |
2808 | =item XS |
2809 | |
2810 | Macro to declare an XSUB and its C parameter list. This is handled by |
2811 | C<xsubpp>. |
2812 | |
cb1a09d0 |
2813 | =item XSRETURN |
2814 | |
2815 | Return from XSUB, indicating number of items on the stack. This is usually |
2816 | handled by C<xsubpp>. |
2817 | |
5fb8527f |
2818 | XSRETURN(int x); |
cb1a09d0 |
2819 | |
2820 | =item XSRETURN_EMPTY |
2821 | |
5fb8527f |
2822 | Return an empty list from an XSUB immediately. |
cb1a09d0 |
2823 | |
2824 | XSRETURN_EMPTY; |
2825 | |
5fb8527f |
2826 | =item XSRETURN_IV |
2827 | |
2828 | Return an integer from an XSUB immediately. Uses C<XST_mIV>. |
2829 | |
2830 | XSRETURN_IV(IV v); |
2831 | |
cb1a09d0 |
2832 | =item XSRETURN_NO |
2833 | |
5fb8527f |
2834 | Return C<&sv_no> from an XSUB immediately. Uses C<XST_mNO>. |
cb1a09d0 |
2835 | |
2836 | XSRETURN_NO; |
2837 | |
5fb8527f |
2838 | =item XSRETURN_NV |
2839 | |
2840 | Return an double from an XSUB immediately. Uses C<XST_mNV>. |
2841 | |
2842 | XSRETURN_NV(NV v); |
2843 | |
2844 | =item XSRETURN_PV |
2845 | |
2846 | Return a copy of a string from an XSUB immediately. Uses C<XST_mPV>. |
2847 | |
2848 | XSRETURN_PV(char *v); |
2849 | |
cb1a09d0 |
2850 | =item XSRETURN_UNDEF |
2851 | |
5fb8527f |
2852 | Return C<&sv_undef> from an XSUB immediately. Uses C<XST_mUNDEF>. |
cb1a09d0 |
2853 | |
2854 | XSRETURN_UNDEF; |
2855 | |
2856 | =item XSRETURN_YES |
2857 | |
5fb8527f |
2858 | Return C<&sv_yes> from an XSUB immediately. Uses C<XST_mYES>. |
cb1a09d0 |
2859 | |
2860 | XSRETURN_YES; |
2861 | |
5fb8527f |
2862 | =item XST_mIV |
2863 | |
2864 | Place an integer into the specified position C<i> on the stack. The value is |
2865 | stored in a new mortal SV. |
2866 | |
2867 | XST_mIV( int i, IV v ); |
2868 | |
2869 | =item XST_mNV |
2870 | |
2871 | Place a double into the specified position C<i> on the stack. The value is |
2872 | stored in a new mortal SV. |
2873 | |
2874 | XST_mNV( int i, NV v ); |
2875 | |
2876 | =item XST_mNO |
2877 | |
2878 | Place C<&sv_no> into the specified position C<i> on the stack. |
2879 | |
2880 | XST_mNO( int i ); |
2881 | |
2882 | =item XST_mPV |
2883 | |
2884 | Place a copy of a string into the specified position C<i> on the stack. The |
2885 | value is stored in a new mortal SV. |
2886 | |
2887 | XST_mPV( int i, char *v ); |
2888 | |
2889 | =item XST_mUNDEF |
2890 | |
2891 | Place C<&sv_undef> into the specified position C<i> on the stack. |
2892 | |
2893 | XST_mUNDEF( int i ); |
2894 | |
2895 | =item XST_mYES |
2896 | |
2897 | Place C<&sv_yes> into the specified position C<i> on the stack. |
2898 | |
2899 | XST_mYES( int i ); |
2900 | |
2901 | =item XS_VERSION |
2902 | |
2903 | The version identifier for an XS module. This is usually handled |
2904 | automatically by C<ExtUtils::MakeMaker>. See C<XS_VERSION_BOOTCHECK>. |
2905 | |
2906 | =item XS_VERSION_BOOTCHECK |
2907 | |
2908 | Macro to verify that a PM module's $VERSION variable matches the XS module's |
2909 | C<XS_VERSION> variable. This is usually handled automatically by |
2910 | C<xsubpp>. See L<perlxs/"The VERSIONCHECK: Keyword">. |
2911 | |
cb1a09d0 |
2912 | =item Zero |
2913 | |
2914 | The XSUB-writer's interface to the C C<memzero> function. The C<d> is the |
2915 | destination, C<n> is the number of items, and C<t> is the type. |
2916 | |
2917 | (void) Zero( d, n, t ); |
2918 | |
2919 | =back |
2920 | |
5f05dabc |
2921 | =head1 EDITOR |
cb1a09d0 |
2922 | |
9607fc9c |
2923 | Jeff Okamoto <F<okamoto@corp.hp.com>> |
cb1a09d0 |
2924 | |
2925 | With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, |
2926 | Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil |
55497cff |
2927 | Bowers, Matthew Green, Tim Bunce, Spider Boardman, and Ulrich Pfeifer. |
cb1a09d0 |
2928 | |
9607fc9c |
2929 | API Listing by Dean Roehrich <F<roehrich@cray.com>>. |
cb1a09d0 |
2930 | |
2931 | =head1 DATE |
2932 | |
dc848c6f |
2933 | Version 31.5: 1997/4/1 |