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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 | |
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37 | The five routines are: |
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38 | |
39 | SV* newSViv(IV); |
40 | SV* newSVnv(double); |
41 | SV* newSVpv(char*, int); |
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42 | SV* newSVpvf(const char*, ...); |
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43 | SV* newSVsv(SV*); |
44 | |
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45 | To change the value of an *already-existing* SV, there are six routines: |
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46 | |
47 | void sv_setiv(SV*, IV); |
48 | void sv_setnv(SV*, double); |
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49 | void sv_setpv(SV*, char*); |
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50 | void sv_setpvn(SV*, char*, int) |
51 | void sv_setpvf(SV*, const char*, ...); |
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52 | void sv_setsv(SV*, SV*); |
53 | |
54 | Notice that you can choose to specify the length of the string to be |
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55 | assigned by using C<sv_setpvn> or C<newSVpv>, or you may allow Perl to |
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56 | calculate the length by using C<sv_setpv> or by specifying 0 as the second |
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57 | argument to C<newSVpv>. Be warned, though, that Perl will determine the |
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58 | string's length by using C<strlen>, which depends on the string terminating |
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59 | with a NUL character. The arguments of C<sv_setpvf> are processed like |
60 | C<sprintf>, and the formatted output becomes the value. |
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61 | |
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62 | All SVs that will contain strings should, but need not, be terminated |
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63 | with a NUL character. If it is not NUL-terminated there is a risk of |
64 | core dumps and corruptions from code which passes the string to C |
65 | functions or system calls which expect a NUL-terminated string. |
66 | Perl's own functions typically add a trailing NUL for this reason. |
67 | Nevertheless, you should be very careful when you pass a string stored |
68 | in an SV to a C function or system call. |
69 | |
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70 | To access the actual value that an SV points to, you can use the macros: |
71 | |
72 | SvIV(SV*) |
73 | SvNV(SV*) |
74 | SvPV(SV*, STRLEN len) |
75 | |
76 | which will automatically coerce the actual scalar type into an IV, double, |
77 | or string. |
78 | |
79 | In the C<SvPV> macro, the length of the string returned is placed into the |
80 | variable C<len> (this is a macro, so you do I<not> use C<&len>). If you do not |
81 | care what the length of the data is, use the global variable C<na>. Remember, |
82 | however, that Perl allows arbitrary strings of data that may both contain |
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83 | NULs and might not be terminated by a NUL. |
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84 | |
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85 | If you want to know if the scalar value is TRUE, you can use: |
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86 | |
87 | SvTRUE(SV*) |
88 | |
89 | Although Perl will automatically grow strings for you, if you need to force |
90 | Perl to allocate more memory for your SV, you can use the macro |
91 | |
92 | SvGROW(SV*, STRLEN newlen) |
93 | |
94 | which will determine if more memory needs to be allocated. If so, it will |
95 | call the function C<sv_grow>. Note that C<SvGROW> can only increase, not |
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96 | decrease, the allocated memory of an SV and that it does not automatically |
97 | add a byte for the a trailing NUL (perl's own string functions typically do |
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98 | C<SvGROW(sv, len + 1)>). |
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99 | |
100 | If you have an SV and want to know what kind of data Perl thinks is stored |
101 | in it, you can use the following macros to check the type of SV you have. |
102 | |
103 | SvIOK(SV*) |
104 | SvNOK(SV*) |
105 | SvPOK(SV*) |
106 | |
107 | You can get and set the current length of the string stored in an SV with |
108 | the following macros: |
109 | |
110 | SvCUR(SV*) |
111 | SvCUR_set(SV*, I32 val) |
112 | |
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113 | You can also get a pointer to the end of the string stored in the SV |
114 | with the macro: |
115 | |
116 | SvEND(SV*) |
117 | |
118 | But note that these last three macros are valid only if C<SvPOK()> is true. |
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119 | |
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120 | If you want to append something to the end of string stored in an C<SV*>, |
121 | you can use the following functions: |
122 | |
123 | void sv_catpv(SV*, char*); |
124 | void sv_catpvn(SV*, char*, int); |
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125 | void sv_catpvf(SV*, const char*, ...); |
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126 | void sv_catsv(SV*, SV*); |
127 | |
128 | The first function calculates the length of the string to be appended by |
129 | using C<strlen>. In the second, you specify the length of the string |
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130 | yourself. The third function processes its arguments like C<sprintf> and |
131 | appends the formatted output. The fourth function extends the string |
132 | stored in the first SV with the string stored in the second SV. It also |
133 | forces the second SV to be interpreted as a string. |
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134 | |
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135 | If you know the name of a scalar variable, you can get a pointer to its SV |
136 | by using the following: |
137 | |
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138 | SV* perl_get_sv("package::varname", FALSE); |
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139 | |
140 | This returns NULL if the variable does not exist. |
141 | |
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142 | If you want to know if this variable (or any other SV) is actually C<defined>, |
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143 | you can call: |
144 | |
145 | SvOK(SV*) |
146 | |
147 | The scalar C<undef> value is stored in an SV instance called C<sv_undef>. Its |
148 | address can be used whenever an C<SV*> is needed. |
149 | |
150 | There are also the two values C<sv_yes> and C<sv_no>, which contain Boolean |
151 | TRUE and FALSE values, respectively. Like C<sv_undef>, their addresses can |
152 | be used whenever an C<SV*> is needed. |
153 | |
154 | Do not be fooled into thinking that C<(SV *) 0> is the same as C<&sv_undef>. |
155 | Take this code: |
156 | |
157 | SV* sv = (SV*) 0; |
158 | if (I-am-to-return-a-real-value) { |
159 | sv = sv_2mortal(newSViv(42)); |
160 | } |
161 | sv_setsv(ST(0), sv); |
162 | |
163 | This code tries to return a new SV (which contains the value 42) if it should |
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164 | return a real value, or undef otherwise. Instead it has returned a NULL |
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165 | pointer which, somewhere down the line, will cause a segmentation violation, |
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166 | bus error, or just weird results. Change the zero to C<&sv_undef> in the first |
167 | line and all will be well. |
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168 | |
169 | To free an SV that you've created, call C<SvREFCNT_dec(SV*)>. Normally this |
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170 | call is not necessary (see L<Reference Counts and Mortality>). |
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171 | |
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172 | =head2 What's Really Stored in an SV? |
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173 | |
174 | Recall that the usual method of determining the type of scalar you have is |
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175 | to use C<Sv*OK> macros. Because a scalar can be both a number and a string, |
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176 | usually these macros will always return TRUE and calling the C<Sv*V> |
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177 | macros will do the appropriate conversion of string to integer/double or |
178 | integer/double to string. |
179 | |
180 | If you I<really> need to know if you have an integer, double, or string |
181 | pointer in an SV, you can use the following three macros instead: |
182 | |
183 | SvIOKp(SV*) |
184 | SvNOKp(SV*) |
185 | SvPOKp(SV*) |
186 | |
187 | These will tell you if you truly have an integer, double, or string pointer |
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188 | stored in your SV. The "p" stands for private. |
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189 | |
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190 | In general, though, it's best to use the C<Sv*V> macros. |
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191 | |
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192 | =head2 Working with AVs |
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193 | |
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194 | There are two ways to create and load an AV. The first method creates an |
195 | empty AV: |
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196 | |
197 | AV* newAV(); |
198 | |
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199 | The second method both creates the AV and initially populates it with SVs: |
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200 | |
201 | AV* av_make(I32 num, SV **ptr); |
202 | |
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203 | The second argument points to an array containing C<num> C<SV*>'s. Once the |
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204 | AV has been created, the SVs can be destroyed, if so desired. |
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205 | |
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206 | Once the AV has been created, the following operations are possible on AVs: |
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207 | |
208 | void av_push(AV*, SV*); |
209 | SV* av_pop(AV*); |
210 | SV* av_shift(AV*); |
211 | void av_unshift(AV*, I32 num); |
212 | |
213 | These should be familiar operations, with the exception of C<av_unshift>. |
214 | This routine adds C<num> elements at the front of the array with the C<undef> |
215 | value. You must then use C<av_store> (described below) to assign values |
216 | to these new elements. |
217 | |
218 | Here are some other functions: |
219 | |
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220 | I32 av_len(AV*); |
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221 | SV** av_fetch(AV*, I32 key, I32 lval); |
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222 | SV** av_store(AV*, I32 key, SV* val); |
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223 | |
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224 | The C<av_len> function returns the highest index value in array (just |
225 | like $#array in Perl). If the array is empty, -1 is returned. The |
226 | C<av_fetch> function returns the value at index C<key>, but if C<lval> |
227 | is non-zero, then C<av_fetch> will store an undef value at that index. |
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228 | The C<av_store> function stores the value C<val> at index C<key>, and does |
229 | not increment the reference count of C<val>. Thus the caller is responsible |
230 | for taking care of that, and if C<av_store> returns NULL, the caller will |
231 | have to decrement the reference count to avoid a memory leak. Note that |
232 | C<av_fetch> and C<av_store> both return C<SV**>'s, not C<SV*>'s as their |
233 | return value. |
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234 | |
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235 | void av_clear(AV*); |
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236 | void av_undef(AV*); |
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237 | void av_extend(AV*, I32 key); |
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238 | |
239 | The C<av_clear> function deletes all the elements in the AV* array, but |
240 | does not actually delete the array itself. The C<av_undef> function will |
241 | delete all the elements in the array plus the array itself. The |
242 | C<av_extend> function extends the array so that it contains C<key> |
243 | elements. If C<key> is less than the current length of the array, then |
244 | nothing is done. |
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245 | |
246 | If you know the name of an array variable, you can get a pointer to its AV |
247 | by using the following: |
248 | |
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249 | AV* perl_get_av("package::varname", FALSE); |
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250 | |
251 | This returns NULL if the variable does not exist. |
252 | |
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253 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
254 | information on how to use the array access functions on tied arrays. |
255 | |
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256 | =head2 Working with HVs |
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257 | |
258 | To create an HV, you use the following routine: |
259 | |
260 | HV* newHV(); |
261 | |
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262 | Once the HV has been created, the following operations are possible on HVs: |
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263 | |
264 | SV** hv_store(HV*, char* key, U32 klen, SV* val, U32 hash); |
265 | SV** hv_fetch(HV*, char* key, U32 klen, I32 lval); |
266 | |
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267 | The C<klen> parameter is the length of the key being passed in (Note that |
268 | you cannot pass 0 in as a value of C<klen> to tell Perl to measure the |
269 | length of the key). The C<val> argument contains the SV pointer to the |
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270 | scalar being stored, and C<hash> is the precomputed hash value (zero if |
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271 | you want C<hv_store> to calculate it for you). The C<lval> parameter |
272 | indicates whether this fetch is actually a part of a store operation, in |
273 | which case a new undefined value will be added to the HV with the supplied |
274 | key and C<hv_fetch> will return as if the value had already existed. |
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275 | |
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276 | Remember that C<hv_store> and C<hv_fetch> return C<SV**>'s and not just |
277 | C<SV*>. To access the scalar value, you must first dereference the return |
278 | value. However, you should check to make sure that the return value is |
279 | not NULL before dereferencing it. |
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280 | |
281 | These two functions check if a hash table entry exists, and deletes it. |
282 | |
283 | bool hv_exists(HV*, char* key, U32 klen); |
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284 | SV* hv_delete(HV*, char* key, U32 klen, I32 flags); |
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285 | |
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286 | If C<flags> does not include the C<G_DISCARD> flag then C<hv_delete> will |
287 | create and return a mortal copy of the deleted value. |
288 | |
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289 | And more miscellaneous functions: |
290 | |
291 | void hv_clear(HV*); |
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292 | void hv_undef(HV*); |
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293 | |
294 | Like their AV counterparts, C<hv_clear> deletes all the entries in the hash |
295 | table but does not actually delete the hash table. The C<hv_undef> deletes |
296 | both the entries and the hash table itself. |
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297 | |
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298 | Perl keeps the actual data in linked list of structures with a typedef of HE. |
299 | These contain the actual key and value pointers (plus extra administrative |
300 | overhead). The key is a string pointer; the value is an C<SV*>. However, |
301 | once you have an C<HE*>, to get the actual key and value, use the routines |
302 | specified below. |
303 | |
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304 | I32 hv_iterinit(HV*); |
305 | /* Prepares starting point to traverse hash table */ |
306 | HE* hv_iternext(HV*); |
307 | /* Get the next entry, and return a pointer to a |
308 | structure that has both the key and value */ |
309 | char* hv_iterkey(HE* entry, I32* retlen); |
310 | /* Get the key from an HE structure and also return |
311 | the length of the key string */ |
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312 | SV* hv_iterval(HV*, HE* entry); |
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313 | /* Return a SV pointer to the value of the HE |
314 | structure */ |
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315 | SV* hv_iternextsv(HV*, char** key, I32* retlen); |
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316 | /* This convenience routine combines hv_iternext, |
317 | hv_iterkey, and hv_iterval. The key and retlen |
318 | arguments are return values for the key and its |
319 | length. The value is returned in the SV* argument */ |
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320 | |
321 | If you know the name of a hash variable, you can get a pointer to its HV |
322 | by using the following: |
323 | |
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324 | HV* perl_get_hv("package::varname", FALSE); |
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325 | |
326 | This returns NULL if the variable does not exist. |
327 | |
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328 | The hash algorithm is defined in the C<PERL_HASH(hash, key, klen)> macro: |
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329 | |
330 | i = klen; |
331 | hash = 0; |
332 | s = key; |
333 | while (i--) |
334 | hash = hash * 33 + *s++; |
335 | |
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336 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
337 | information on how to use the hash access functions on tied hashes. |
338 | |
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339 | =head2 Hash API Extensions |
340 | |
341 | Beginning with version 5.004, the following functions are also supported: |
342 | |
343 | HE* hv_fetch_ent (HV* tb, SV* key, I32 lval, U32 hash); |
344 | HE* hv_store_ent (HV* tb, SV* key, SV* val, U32 hash); |
345 | |
346 | bool hv_exists_ent (HV* tb, SV* key, U32 hash); |
347 | SV* hv_delete_ent (HV* tb, SV* key, I32 flags, U32 hash); |
348 | |
349 | SV* hv_iterkeysv (HE* entry); |
350 | |
351 | Note that these functions take C<SV*> keys, which simplifies writing |
352 | of extension code that deals with hash structures. These functions |
353 | also allow passing of C<SV*> keys to C<tie> functions without forcing |
354 | you to stringify the keys (unlike the previous set of functions). |
355 | |
356 | They also return and accept whole hash entries (C<HE*>), making their |
357 | use more efficient (since the hash number for a particular string |
358 | doesn't have to be recomputed every time). See L<API LISTING> later in |
359 | this document for detailed descriptions. |
360 | |
361 | The following macros must always be used to access the contents of hash |
362 | entries. Note that the arguments to these macros must be simple |
363 | variables, since they may get evaluated more than once. See |
364 | L<API LISTING> later in this document for detailed descriptions of these |
365 | macros. |
366 | |
367 | HePV(HE* he, STRLEN len) |
368 | HeVAL(HE* he) |
369 | HeHASH(HE* he) |
370 | HeSVKEY(HE* he) |
371 | HeSVKEY_force(HE* he) |
372 | HeSVKEY_set(HE* he, SV* sv) |
373 | |
374 | These two lower level macros are defined, but must only be used when |
375 | dealing with keys that are not C<SV*>s: |
376 | |
377 | HeKEY(HE* he) |
378 | HeKLEN(HE* he) |
379 | |
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380 | Note that both C<hv_store> and C<hv_store_ent> do not increment the |
381 | reference count of the stored C<val>, which is the caller's responsibility. |
382 | If these functions return a NULL value, the caller will usually have to |
383 | decrement the reference count of C<val> to avoid a memory leak. |
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384 | |
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385 | =head2 References |
386 | |
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387 | References are a special type of scalar that point to other data types |
388 | (including references). |
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389 | |
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390 | To create a reference, use either of the following functions: |
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391 | |
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392 | SV* newRV_inc((SV*) thing); |
393 | SV* newRV_noinc((SV*) thing); |
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394 | |
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395 | The C<thing> argument can be any of an C<SV*>, C<AV*>, or C<HV*>. The |
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396 | functions are identical except that C<newRV_inc> increments the reference |
397 | count of the C<thing>, while C<newRV_noinc> does not. For historical |
398 | reasons, C<newRV> is a synonym for C<newRV_inc>. |
399 | |
400 | Once you have a reference, you can use the following macro to dereference |
401 | the reference: |
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402 | |
403 | SvRV(SV*) |
404 | |
405 | then call the appropriate routines, casting the returned C<SV*> to either an |
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406 | C<AV*> or C<HV*>, if required. |
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407 | |
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408 | To determine if an SV is a reference, you can use the following macro: |
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409 | |
410 | SvROK(SV*) |
411 | |
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412 | To discover what type of value the reference refers to, use the following |
413 | macro and then check the return value. |
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414 | |
415 | SvTYPE(SvRV(SV*)) |
416 | |
417 | The most useful types that will be returned are: |
418 | |
419 | SVt_IV Scalar |
420 | SVt_NV Scalar |
421 | SVt_PV Scalar |
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422 | SVt_RV Scalar |
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423 | SVt_PVAV Array |
424 | SVt_PVHV Hash |
425 | SVt_PVCV Code |
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426 | SVt_PVGV Glob (possible a file handle) |
427 | SVt_PVMG Blessed or Magical Scalar |
428 | |
429 | See the sv.h header file for more details. |
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430 | |
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431 | =head2 Blessed References and Class Objects |
432 | |
433 | References are also used to support object-oriented programming. In the |
434 | OO lexicon, an object is simply a reference that has been blessed into a |
435 | package (or class). Once blessed, the programmer may now use the reference |
436 | to access the various methods in the class. |
437 | |
438 | A reference can be blessed into a package with the following function: |
439 | |
440 | SV* sv_bless(SV* sv, HV* stash); |
441 | |
442 | The C<sv> argument must be a reference. The C<stash> argument specifies |
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443 | which class the reference will belong to. See |
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444 | L<Stashes and Globs> for information on converting class names into stashes. |
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445 | |
446 | /* Still under construction */ |
447 | |
448 | Upgrades rv to reference if not already one. Creates new SV for rv to |
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449 | point to. If C<classname> is non-null, the SV is blessed into the specified |
450 | class. SV is returned. |
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451 | |
452 | SV* newSVrv(SV* rv, char* classname); |
453 | |
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454 | Copies integer or double into an SV whose reference is C<rv>. SV is blessed |
455 | if C<classname> is non-null. |
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456 | |
457 | SV* sv_setref_iv(SV* rv, char* classname, IV iv); |
458 | SV* sv_setref_nv(SV* rv, char* classname, NV iv); |
459 | |
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460 | Copies the pointer value (I<the address, not the string!>) into an SV whose |
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461 | reference is rv. SV is blessed if C<classname> is non-null. |
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462 | |
463 | SV* sv_setref_pv(SV* rv, char* classname, PV iv); |
464 | |
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465 | Copies string into an SV whose reference is C<rv>. Set length to 0 to let |
466 | Perl calculate the string length. SV is blessed if C<classname> is non-null. |
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467 | |
468 | SV* sv_setref_pvn(SV* rv, char* classname, PV iv, int length); |
469 | |
470 | int sv_isa(SV* sv, char* name); |
471 | int sv_isobject(SV* sv); |
472 | |
5f05dabc |
473 | =head2 Creating New Variables |
cb1a09d0 |
474 | |
5f05dabc |
475 | To create a new Perl variable with an undef value which can be accessed from |
476 | your Perl script, use the following routines, depending on the variable type. |
cb1a09d0 |
477 | |
5f05dabc |
478 | SV* perl_get_sv("package::varname", TRUE); |
479 | AV* perl_get_av("package::varname", TRUE); |
480 | HV* perl_get_hv("package::varname", TRUE); |
cb1a09d0 |
481 | |
482 | Notice the use of TRUE as the second parameter. The new variable can now |
483 | be set, using the routines appropriate to the data type. |
484 | |
5f05dabc |
485 | There are additional macros whose values may be bitwise OR'ed with the |
486 | C<TRUE> argument to enable certain extra features. Those bits are: |
cb1a09d0 |
487 | |
5f05dabc |
488 | GV_ADDMULTI Marks the variable as multiply defined, thus preventing the |
54310121 |
489 | "Name <varname> used only once: possible typo" warning. |
07fa94a1 |
490 | GV_ADDWARN Issues the warning "Had to create <varname> unexpectedly" if |
491 | the variable did not exist before the function was called. |
cb1a09d0 |
492 | |
07fa94a1 |
493 | If you do not specify a package name, the variable is created in the current |
494 | package. |
cb1a09d0 |
495 | |
5f05dabc |
496 | =head2 Reference Counts and Mortality |
a0d0e21e |
497 | |
54310121 |
498 | Perl uses an reference count-driven garbage collection mechanism. SVs, |
499 | AVs, or HVs (xV for short in the following) start their life with a |
55497cff |
500 | reference count of 1. If the reference count of an xV ever drops to 0, |
07fa94a1 |
501 | then it will be destroyed and its memory made available for reuse. |
55497cff |
502 | |
503 | This normally doesn't happen at the Perl level unless a variable is |
5f05dabc |
504 | undef'ed or the last variable holding a reference to it is changed or |
505 | overwritten. At the internal level, however, reference counts can be |
55497cff |
506 | manipulated with the following macros: |
507 | |
508 | int SvREFCNT(SV* sv); |
5f05dabc |
509 | SV* SvREFCNT_inc(SV* sv); |
55497cff |
510 | void SvREFCNT_dec(SV* sv); |
511 | |
512 | However, there is one other function which manipulates the reference |
07fa94a1 |
513 | count of its argument. The C<newRV_inc> function, you will recall, |
514 | creates a reference to the specified argument. As a side effect, |
515 | it increments the argument's reference count. If this is not what |
516 | you want, use C<newRV_noinc> instead. |
517 | |
518 | For example, imagine you want to return a reference from an XSUB function. |
519 | Inside the XSUB routine, you create an SV which initially has a reference |
520 | count of one. Then you call C<newRV_inc>, passing it the just-created SV. |
5f05dabc |
521 | This returns the reference as a new SV, but the reference count of the |
522 | SV you passed to C<newRV_inc> has been incremented to two. Now you |
07fa94a1 |
523 | return the reference from the XSUB routine and forget about the SV. |
524 | But Perl hasn't! Whenever the returned reference is destroyed, the |
525 | reference count of the original SV is decreased to one and nothing happens. |
526 | The SV will hang around without any way to access it until Perl itself |
527 | terminates. This is a memory leak. |
5f05dabc |
528 | |
529 | The correct procedure, then, is to use C<newRV_noinc> instead of |
faed5253 |
530 | C<newRV_inc>. Then, if and when the last reference is destroyed, |
531 | the reference count of the SV will go to zero and it will be destroyed, |
07fa94a1 |
532 | stopping any memory leak. |
55497cff |
533 | |
5f05dabc |
534 | There are some convenience functions available that can help with the |
54310121 |
535 | destruction of xVs. These functions introduce the concept of "mortality". |
07fa94a1 |
536 | An xV that is mortal has had its reference count marked to be decremented, |
537 | but not actually decremented, until "a short time later". Generally the |
538 | term "short time later" means a single Perl statement, such as a call to |
54310121 |
539 | an XSUB function. The actual determinant for when mortal xVs have their |
07fa94a1 |
540 | reference count decremented depends on two macros, SAVETMPS and FREETMPS. |
541 | See L<perlcall> and L<perlxs> for more details on these macros. |
55497cff |
542 | |
543 | "Mortalization" then is at its simplest a deferred C<SvREFCNT_dec>. |
544 | However, if you mortalize a variable twice, the reference count will |
545 | later be decremented twice. |
546 | |
547 | You should be careful about creating mortal variables. Strange things |
548 | can happen if you make the same value mortal within multiple contexts, |
5f05dabc |
549 | or if you make a variable mortal multiple times. |
a0d0e21e |
550 | |
551 | To create a mortal variable, use the functions: |
552 | |
553 | SV* sv_newmortal() |
554 | SV* sv_2mortal(SV*) |
555 | SV* sv_mortalcopy(SV*) |
556 | |
5f05dabc |
557 | The first call creates a mortal SV, the second converts an existing |
558 | SV to a mortal SV (and thus defers a call to C<SvREFCNT_dec>), and the |
559 | third creates a mortal copy of an existing SV. |
a0d0e21e |
560 | |
54310121 |
561 | The mortal routines are not just for SVs -- AVs and HVs can be |
faed5253 |
562 | made mortal by passing their address (type-casted to C<SV*>) to the |
07fa94a1 |
563 | C<sv_2mortal> or C<sv_mortalcopy> routines. |
a0d0e21e |
564 | |
5f05dabc |
565 | =head2 Stashes and Globs |
a0d0e21e |
566 | |
aa689395 |
567 | A "stash" is a hash that contains all of the different objects that |
568 | are contained within a package. Each key of the stash is a symbol |
569 | name (shared by all the different types of objects that have the same |
570 | name), and each value in the hash table is a GV (Glob Value). This GV |
571 | in turn contains references to the various objects of that name, |
572 | including (but not limited to) the following: |
cb1a09d0 |
573 | |
a0d0e21e |
574 | Scalar Value |
575 | Array Value |
576 | Hash Value |
577 | File Handle |
578 | Directory Handle |
579 | Format |
580 | Subroutine |
581 | |
5f05dabc |
582 | There is a single stash called "defstash" that holds the items that exist |
583 | in the "main" package. To get at the items in other packages, append the |
584 | string "::" to the package name. The items in the "Foo" package are in |
585 | the stash "Foo::" in defstash. The items in the "Bar::Baz" package are |
586 | in the stash "Baz::" in "Bar::"'s stash. |
a0d0e21e |
587 | |
d1b91892 |
588 | To get the stash pointer for a particular package, use the function: |
a0d0e21e |
589 | |
590 | HV* gv_stashpv(char* name, I32 create) |
591 | HV* gv_stashsv(SV*, I32 create) |
592 | |
593 | The first function takes a literal string, the second uses the string stored |
d1b91892 |
594 | in the SV. Remember that a stash is just a hash table, so you get back an |
cb1a09d0 |
595 | C<HV*>. The C<create> flag will create a new package if it is set. |
a0d0e21e |
596 | |
597 | The name that C<gv_stash*v> wants is the name of the package whose symbol table |
598 | you want. The default package is called C<main>. If you have multiply nested |
d1b91892 |
599 | packages, pass their names to C<gv_stash*v>, separated by C<::> as in the Perl |
600 | language itself. |
a0d0e21e |
601 | |
602 | Alternately, if you have an SV that is a blessed reference, you can find |
603 | out the stash pointer by using: |
604 | |
605 | HV* SvSTASH(SvRV(SV*)); |
606 | |
607 | then use the following to get the package name itself: |
608 | |
609 | char* HvNAME(HV* stash); |
610 | |
5f05dabc |
611 | If you need to bless or re-bless an object you can use the following |
612 | function: |
a0d0e21e |
613 | |
614 | SV* sv_bless(SV*, HV* stash) |
615 | |
616 | where the first argument, an C<SV*>, must be a reference, and the second |
617 | argument is a stash. The returned C<SV*> can now be used in the same way |
618 | as any other SV. |
619 | |
d1b91892 |
620 | For more information on references and blessings, consult L<perlref>. |
621 | |
54310121 |
622 | =head2 Double-Typed SVs |
0a753a76 |
623 | |
624 | Scalar variables normally contain only one type of value, an integer, |
625 | double, pointer, or reference. Perl will automatically convert the |
626 | actual scalar data from the stored type into the requested type. |
627 | |
628 | Some scalar variables contain more than one type of scalar data. For |
629 | example, the variable C<$!> contains either the numeric value of C<errno> |
630 | or its string equivalent from either C<strerror> or C<sys_errlist[]>. |
631 | |
632 | To force multiple data values into an SV, you must do two things: use the |
633 | C<sv_set*v> routines to add the additional scalar type, then set a flag |
634 | so that Perl will believe it contains more than one type of data. The |
635 | four macros to set the flags are: |
636 | |
637 | SvIOK_on |
638 | SvNOK_on |
639 | SvPOK_on |
640 | SvROK_on |
641 | |
642 | The particular macro you must use depends on which C<sv_set*v> routine |
643 | you called first. This is because every C<sv_set*v> routine turns on |
644 | only the bit for the particular type of data being set, and turns off |
645 | all the rest. |
646 | |
647 | For example, to create a new Perl variable called "dberror" that contains |
648 | both the numeric and descriptive string error values, you could use the |
649 | following code: |
650 | |
651 | extern int dberror; |
652 | extern char *dberror_list; |
653 | |
654 | SV* sv = perl_get_sv("dberror", TRUE); |
655 | sv_setiv(sv, (IV) dberror); |
656 | sv_setpv(sv, dberror_list[dberror]); |
657 | SvIOK_on(sv); |
658 | |
659 | If the order of C<sv_setiv> and C<sv_setpv> had been reversed, then the |
660 | macro C<SvPOK_on> would need to be called instead of C<SvIOK_on>. |
661 | |
662 | =head2 Magic Variables |
a0d0e21e |
663 | |
d1b91892 |
664 | [This section still under construction. Ignore everything here. Post no |
665 | bills. Everything not permitted is forbidden.] |
666 | |
d1b91892 |
667 | Any SV may be magical, that is, it has special features that a normal |
668 | SV does not have. These features are stored in the SV structure in a |
5f05dabc |
669 | linked list of C<struct magic>'s, typedef'ed to C<MAGIC>. |
d1b91892 |
670 | |
671 | struct magic { |
672 | MAGIC* mg_moremagic; |
673 | MGVTBL* mg_virtual; |
674 | U16 mg_private; |
675 | char mg_type; |
676 | U8 mg_flags; |
677 | SV* mg_obj; |
678 | char* mg_ptr; |
679 | I32 mg_len; |
680 | }; |
681 | |
682 | Note this is current as of patchlevel 0, and could change at any time. |
683 | |
684 | =head2 Assigning Magic |
685 | |
686 | Perl adds magic to an SV using the sv_magic function: |
687 | |
688 | void sv_magic(SV* sv, SV* obj, int how, char* name, I32 namlen); |
689 | |
690 | The C<sv> argument is a pointer to the SV that is to acquire a new magical |
691 | feature. |
692 | |
693 | If C<sv> is not already magical, Perl uses the C<SvUPGRADE> macro to |
694 | set the C<SVt_PVMG> flag for the C<sv>. Perl then continues by adding |
695 | it to the beginning of the linked list of magical features. Any prior |
696 | entry of the same type of magic is deleted. Note that this can be |
5fb8527f |
697 | overridden, and multiple instances of the same type of magic can be |
d1b91892 |
698 | associated with an SV. |
699 | |
54310121 |
700 | The C<name> and C<namlen> arguments are used to associate a string with |
701 | the magic, typically the name of a variable. C<namlen> is stored in the |
702 | C<mg_len> field and if C<name> is non-null and C<namlen> >= 0 a malloc'd |
d1b91892 |
703 | copy of the name is stored in C<mg_ptr> field. |
704 | |
705 | The sv_magic function uses C<how> to determine which, if any, predefined |
706 | "Magic Virtual Table" should be assigned to the C<mg_virtual> field. |
cb1a09d0 |
707 | See the "Magic Virtual Table" section below. The C<how> argument is also |
708 | stored in the C<mg_type> field. |
d1b91892 |
709 | |
710 | The C<obj> argument is stored in the C<mg_obj> field of the C<MAGIC> |
711 | structure. If it is not the same as the C<sv> argument, the reference |
712 | count of the C<obj> object is incremented. If it is the same, or if |
04343c6d |
713 | the C<how> argument is "#", or if it is a NULL pointer, then C<obj> is |
d1b91892 |
714 | merely stored, without the reference count being incremented. |
715 | |
cb1a09d0 |
716 | There is also a function to add magic to an C<HV>: |
717 | |
718 | void hv_magic(HV *hv, GV *gv, int how); |
719 | |
720 | This simply calls C<sv_magic> and coerces the C<gv> argument into an C<SV>. |
721 | |
722 | To remove the magic from an SV, call the function sv_unmagic: |
723 | |
724 | void sv_unmagic(SV *sv, int type); |
725 | |
726 | The C<type> argument should be equal to the C<how> value when the C<SV> |
727 | was initially made magical. |
728 | |
d1b91892 |
729 | =head2 Magic Virtual Tables |
730 | |
731 | The C<mg_virtual> field in the C<MAGIC> structure is a pointer to a |
732 | C<MGVTBL>, which is a structure of function pointers and stands for |
733 | "Magic Virtual Table" to handle the various operations that might be |
734 | applied to that variable. |
735 | |
736 | The C<MGVTBL> has five pointers to the following routine types: |
737 | |
738 | int (*svt_get)(SV* sv, MAGIC* mg); |
739 | int (*svt_set)(SV* sv, MAGIC* mg); |
740 | U32 (*svt_len)(SV* sv, MAGIC* mg); |
741 | int (*svt_clear)(SV* sv, MAGIC* mg); |
742 | int (*svt_free)(SV* sv, MAGIC* mg); |
743 | |
744 | This MGVTBL structure is set at compile-time in C<perl.h> and there are |
745 | currently 19 types (or 21 with overloading turned on). These different |
746 | structures contain pointers to various routines that perform additional |
747 | actions depending on which function is being called. |
748 | |
749 | Function pointer Action taken |
750 | ---------------- ------------ |
751 | svt_get Do something after the value of the SV is retrieved. |
752 | svt_set Do something after the SV is assigned a value. |
753 | svt_len Report on the SV's length. |
754 | svt_clear Clear something the SV represents. |
755 | svt_free Free any extra storage associated with the SV. |
756 | |
757 | For instance, the MGVTBL structure called C<vtbl_sv> (which corresponds |
758 | to an C<mg_type> of '\0') contains: |
759 | |
760 | { magic_get, magic_set, magic_len, 0, 0 } |
761 | |
762 | Thus, when an SV is determined to be magical and of type '\0', if a get |
763 | operation is being performed, the routine C<magic_get> is called. All |
764 | the various routines for the various magical types begin with C<magic_>. |
765 | |
766 | The current kinds of Magic Virtual Tables are: |
767 | |
bdbeb323 |
768 | mg_type MGVTBL Type of magic |
5f05dabc |
769 | ------- ------ ---------------------------- |
bdbeb323 |
770 | \0 vtbl_sv Special scalar variable |
771 | A vtbl_amagic %OVERLOAD hash |
772 | a vtbl_amagicelem %OVERLOAD hash element |
773 | c (none) Holds overload table (AMT) on stash |
774 | B vtbl_bm Boyer-Moore (fast string search) |
d1b91892 |
775 | E vtbl_env %ENV hash |
776 | e vtbl_envelem %ENV hash element |
bdbeb323 |
777 | f vtbl_fm Formline ('compiled' format) |
778 | g vtbl_mglob m//g target / study()ed string |
d1b91892 |
779 | I vtbl_isa @ISA array |
780 | i vtbl_isaelem @ISA array element |
bdbeb323 |
781 | k vtbl_nkeys scalar(keys()) lvalue |
782 | L (none) Debugger %_<filename |
783 | l vtbl_dbline Debugger %_<filename element |
44a8e56a |
784 | o vtbl_collxfrm Locale transformation |
bdbeb323 |
785 | P vtbl_pack Tied array or hash |
786 | p vtbl_packelem Tied array or hash element |
787 | q vtbl_packelem Tied scalar or handle |
788 | S vtbl_sig %SIG hash |
789 | s vtbl_sigelem %SIG hash element |
d1b91892 |
790 | t vtbl_taint Taintedness |
bdbeb323 |
791 | U vtbl_uvar Available for use by extensions |
792 | v vtbl_vec vec() lvalue |
793 | x vtbl_substr substr() lvalue |
794 | y vtbl_defelem Shadow "foreach" iterator variable / |
795 | smart parameter vivification |
796 | * vtbl_glob GV (typeglob) |
797 | # vtbl_arylen Array length ($#ary) |
798 | . vtbl_pos pos() lvalue |
799 | ~ (none) Available for use by extensions |
d1b91892 |
800 | |
68dc0745 |
801 | When an uppercase and lowercase letter both exist in the table, then the |
802 | uppercase letter is used to represent some kind of composite type (a list |
803 | or a hash), and the lowercase letter is used to represent an element of |
d1b91892 |
804 | that composite type. |
805 | |
bdbeb323 |
806 | The '~' and 'U' magic types are defined specifically for use by |
807 | extensions and will not be used by perl itself. Extensions can use |
808 | '~' magic to 'attach' private information to variables (typically |
809 | objects). This is especially useful because there is no way for |
810 | normal perl code to corrupt this private information (unlike using |
811 | extra elements of a hash object). |
812 | |
813 | Similarly, 'U' magic can be used much like tie() to call a C function |
814 | any time a scalar's value is used or changed. The C<MAGIC>'s |
815 | C<mg_ptr> field points to a C<ufuncs> structure: |
816 | |
817 | struct ufuncs { |
818 | I32 (*uf_val)(IV, SV*); |
819 | I32 (*uf_set)(IV, SV*); |
820 | IV uf_index; |
821 | }; |
822 | |
823 | When the SV is read from or written to, the C<uf_val> or C<uf_set> |
824 | function will be called with C<uf_index> as the first arg and a |
825 | pointer to the SV as the second. |
5f05dabc |
826 | |
bdbeb323 |
827 | Note that because multiple extensions may be using '~' or 'U' magic, |
828 | it is important for extensions to take extra care to avoid conflict. |
829 | Typically only using the magic on objects blessed into the same class |
830 | as the extension is sufficient. For '~' magic, it may also be |
831 | appropriate to add an I32 'signature' at the top of the private data |
832 | area and check that. |
5f05dabc |
833 | |
d1b91892 |
834 | =head2 Finding Magic |
835 | |
836 | MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */ |
837 | |
838 | This routine returns a pointer to the C<MAGIC> structure stored in the SV. |
839 | If the SV does not have that magical feature, C<NULL> is returned. Also, |
54310121 |
840 | if the SV is not of type SVt_PVMG, Perl may core dump. |
d1b91892 |
841 | |
842 | int mg_copy(SV* sv, SV* nsv, char* key, STRLEN klen); |
843 | |
844 | This routine checks to see what types of magic C<sv> has. If the mg_type |
68dc0745 |
845 | field is an uppercase letter, then the mg_obj is copied to C<nsv>, but |
846 | the mg_type field is changed to be the lowercase letter. |
a0d0e21e |
847 | |
04343c6d |
848 | =head2 Understanding the Magic of Tied Hashes and Arrays |
849 | |
850 | Tied hashes and arrays are magical beasts of the 'P' magic type. |
9edb2b46 |
851 | |
852 | WARNING: As of the 5.004 release, proper usage of the array and hash |
853 | access functions requires understanding a few caveats. Some |
854 | of these caveats are actually considered bugs in the API, to be fixed |
855 | in later releases, and are bracketed with [MAYCHANGE] below. If |
856 | you find yourself actually applying such information in this section, be |
857 | aware that the behavior may change in the future, umm, without warning. |
04343c6d |
858 | |
859 | The C<av_store> function, when given a tied array argument, merely |
860 | copies the magic of the array onto the value to be "stored", using |
861 | C<mg_copy>. It may also return NULL, indicating that the value did not |
9edb2b46 |
862 | actually need to be stored in the array. [MAYCHANGE] After a call to |
863 | C<av_store> on a tied array, the caller will usually need to call |
864 | C<mg_set(val)> to actually invoke the perl level "STORE" method on the |
865 | TIEARRAY object. If C<av_store> did return NULL, a call to |
866 | C<SvREFCNT_dec(val)> will also be usually necessary to avoid a memory |
867 | leak. [/MAYCHANGE] |
04343c6d |
868 | |
869 | The previous paragraph is applicable verbatim to tied hash access using the |
870 | C<hv_store> and C<hv_store_ent> functions as well. |
871 | |
872 | C<av_fetch> and the corresponding hash functions C<hv_fetch> and |
873 | C<hv_fetch_ent> actually return an undefined mortal value whose magic |
874 | has been initialized using C<mg_copy>. Note the value so returned does not |
9edb2b46 |
875 | need to be deallocated, as it is already mortal. [MAYCHANGE] But you will |
876 | need to call C<mg_get()> on the returned value in order to actually invoke |
877 | the perl level "FETCH" method on the underlying TIE object. Similarly, |
04343c6d |
878 | you may also call C<mg_set()> on the return value after possibly assigning |
879 | a suitable value to it using C<sv_setsv>, which will invoke the "STORE" |
9edb2b46 |
880 | method on the TIE object. [/MAYCHANGE] |
04343c6d |
881 | |
9edb2b46 |
882 | [MAYCHANGE] |
04343c6d |
883 | In other words, the array or hash fetch/store functions don't really |
884 | fetch and store actual values in the case of tied arrays and hashes. They |
885 | merely call C<mg_copy> to attach magic to the values that were meant to be |
886 | "stored" or "fetched". Later calls to C<mg_get> and C<mg_set> actually |
887 | do the job of invoking the TIE methods on the underlying objects. Thus |
9edb2b46 |
888 | the magic mechanism currently implements a kind of lazy access to arrays |
04343c6d |
889 | and hashes. |
890 | |
891 | Currently (as of perl version 5.004), use of the hash and array access |
892 | functions requires the user to be aware of whether they are operating on |
9edb2b46 |
893 | "normal" hashes and arrays, or on their tied variants. The API may be |
894 | changed to provide more transparent access to both tied and normal data |
895 | types in future versions. |
896 | [/MAYCHANGE] |
04343c6d |
897 | |
898 | You would do well to understand that the TIEARRAY and TIEHASH interfaces |
899 | are mere sugar to invoke some perl method calls while using the uniform hash |
900 | and array syntax. The use of this sugar imposes some overhead (typically |
901 | about two to four extra opcodes per FETCH/STORE operation, in addition to |
902 | the creation of all the mortal variables required to invoke the methods). |
903 | This overhead will be comparatively small if the TIE methods are themselves |
904 | substantial, but if they are only a few statements long, the overhead |
905 | will not be insignificant. |
906 | |
d1c897a1 |
907 | =head2 Localizing changes |
908 | |
909 | Perl has a very handy construction |
910 | |
911 | { |
912 | local $var = 2; |
913 | ... |
914 | } |
915 | |
916 | This construction is I<approximately> equivalent to |
917 | |
918 | { |
919 | my $oldvar = $var; |
920 | $var = 2; |
921 | ... |
922 | $var = $oldvar; |
923 | } |
924 | |
925 | The biggest difference is that the first construction would |
926 | reinstate the initial value of $var, irrespective of how control exits |
927 | the block: C<goto>, C<return>, C<die>/C<eval> etc. It is a little bit |
928 | more efficient as well. |
929 | |
930 | There is a way to achieve a similar task from C via Perl API: create a |
931 | I<pseudo-block>, and arrange for some changes to be automatically |
932 | undone at the end of it, either explicit, or via a non-local exit (via |
933 | die()). A I<block>-like construct is created by a pair of |
934 | C<ENTER>/C<LEAVE> macros (see L<perlcall/EXAMPLE/"Returning a |
935 | Scalar">). Such a construct may be created specially for some |
936 | important localized task, or an existing one (like boundaries of |
937 | enclosing Perl subroutine/block, or an existing pair for freeing TMPs) |
938 | may be used. (In the second case the overhead of additional |
939 | localization must be almost negligible.) Note that any XSUB is |
940 | automatically enclosed in an C<ENTER>/C<LEAVE> pair. |
941 | |
942 | Inside such a I<pseudo-block> the following service is available: |
943 | |
944 | =over |
945 | |
946 | =item C<SAVEINT(int i)> |
947 | |
948 | =item C<SAVEIV(IV i)> |
949 | |
950 | =item C<SAVEI32(I32 i)> |
951 | |
952 | =item C<SAVELONG(long i)> |
953 | |
954 | These macros arrange things to restore the value of integer variable |
955 | C<i> at the end of enclosing I<pseudo-block>. |
956 | |
957 | =item C<SAVESPTR(s)> |
958 | |
959 | =item C<SAVEPPTR(p)> |
960 | |
961 | These macros arrange things to restore the value of pointers C<s> and |
962 | C<p>. C<s> must be a pointer of a type which survives conversion to |
963 | C<SV*> and back, C<p> should be able to survive conversion to C<char*> |
964 | and back. |
965 | |
966 | =item C<SAVEFREESV(SV *sv)> |
967 | |
968 | The refcount of C<sv> would be decremented at the end of |
969 | I<pseudo-block>. This is similar to C<sv_2mortal>, which should (?) be |
970 | used instead. |
971 | |
972 | =item C<SAVEFREEOP(OP *op)> |
973 | |
974 | The C<OP *> is op_free()ed at the end of I<pseudo-block>. |
975 | |
976 | =item C<SAVEFREEPV(p)> |
977 | |
978 | The chunk of memory which is pointed to by C<p> is Safefree()ed at the |
979 | end of I<pseudo-block>. |
980 | |
981 | =item C<SAVECLEARSV(SV *sv)> |
982 | |
983 | Clears a slot in the current scratchpad which corresponds to C<sv> at |
984 | the end of I<pseudo-block>. |
985 | |
986 | =item C<SAVEDELETE(HV *hv, char *key, I32 length)> |
987 | |
988 | The key C<key> of C<hv> is deleted at the end of I<pseudo-block>. The |
989 | string pointed to by C<key> is Safefree()ed. If one has a I<key> in |
990 | short-lived storage, the corresponding string may be reallocated like |
991 | this: |
992 | |
993 | SAVEDELETE(defstash, savepv(tmpbuf), strlen(tmpbuf)); |
994 | |
995 | =item C<SAVEDESTRUCTOR(f,p)> |
996 | |
997 | At the end of I<pseudo-block> the function C<f> is called with the |
998 | only argument (of type C<void*>) C<p>. |
999 | |
1000 | =item C<SAVESTACK_POS()> |
1001 | |
1002 | The current offset on the Perl internal stack (cf. C<SP>) is restored |
1003 | at the end of I<pseudo-block>. |
1004 | |
1005 | =back |
1006 | |
1007 | The following API list contains functions, thus one needs to |
1008 | provide pointers to the modifiable data explicitly (either C pointers, |
1009 | or Perlish C<GV *>s). Where the above macros take C<int>, a similar |
1010 | function takes C<int *>. |
1011 | |
1012 | =over |
1013 | |
1014 | =item C<SV* save_scalar(GV *gv)> |
1015 | |
1016 | Equivalent to Perl code C<local $gv>. |
1017 | |
1018 | =item C<AV* save_ary(GV *gv)> |
1019 | |
1020 | =item C<HV* save_hash(GV *gv)> |
1021 | |
1022 | Similar to C<save_scalar>, but localize C<@gv> and C<%gv>. |
1023 | |
1024 | =item C<void save_item(SV *item)> |
1025 | |
1026 | Duplicates the current value of C<SV>, on the exit from the current |
1027 | C<ENTER>/C<LEAVE> I<pseudo-block> will restore the value of C<SV> |
1028 | using the stored value. |
1029 | |
1030 | =item C<void save_list(SV **sarg, I32 maxsarg)> |
1031 | |
1032 | A variant of C<save_item> which takes multiple arguments via an array |
1033 | C<sarg> of C<SV*> of length C<maxsarg>. |
1034 | |
1035 | =item C<SV* save_svref(SV **sptr)> |
1036 | |
1037 | Similar to C<save_scalar>, but will reinstate a C<SV *>. |
1038 | |
1039 | =item C<void save_aptr(AV **aptr)> |
1040 | |
1041 | =item C<void save_hptr(HV **hptr)> |
1042 | |
1043 | Similar to C<save_svref>, but localize C<AV *> and C<HV *>. |
1044 | |
1045 | =back |
1046 | |
1047 | The C<Alias> module implements localization of the basic types within the |
1048 | I<caller's scope>. People who are interested in how to localize things in |
1049 | the containing scope should take a look there too. |
1050 | |
0a753a76 |
1051 | =head1 Subroutines |
a0d0e21e |
1052 | |
68dc0745 |
1053 | =head2 XSUBs and the Argument Stack |
5f05dabc |
1054 | |
1055 | The XSUB mechanism is a simple way for Perl programs to access C subroutines. |
1056 | An XSUB routine will have a stack that contains the arguments from the Perl |
1057 | program, and a way to map from the Perl data structures to a C equivalent. |
1058 | |
1059 | The stack arguments are accessible through the C<ST(n)> macro, which returns |
1060 | the C<n>'th stack argument. Argument 0 is the first argument passed in the |
1061 | Perl subroutine call. These arguments are C<SV*>, and can be used anywhere |
1062 | an C<SV*> is used. |
1063 | |
1064 | Most of the time, output from the C routine can be handled through use of |
1065 | the RETVAL and OUTPUT directives. However, there are some cases where the |
1066 | argument stack is not already long enough to handle all the return values. |
1067 | An example is the POSIX tzname() call, which takes no arguments, but returns |
1068 | two, the local time zone's standard and summer time abbreviations. |
1069 | |
1070 | To handle this situation, the PPCODE directive is used and the stack is |
1071 | extended using the macro: |
1072 | |
1073 | EXTEND(sp, num); |
1074 | |
1075 | where C<sp> is the stack pointer, and C<num> is the number of elements the |
1076 | stack should be extended by. |
1077 | |
1078 | Now that there is room on the stack, values can be pushed on it using the |
54310121 |
1079 | macros to push IVs, doubles, strings, and SV pointers respectively: |
5f05dabc |
1080 | |
1081 | PUSHi(IV) |
1082 | PUSHn(double) |
1083 | PUSHp(char*, I32) |
1084 | PUSHs(SV*) |
1085 | |
1086 | And now the Perl program calling C<tzname>, the two values will be assigned |
1087 | as in: |
1088 | |
1089 | ($standard_abbrev, $summer_abbrev) = POSIX::tzname; |
1090 | |
1091 | An alternate (and possibly simpler) method to pushing values on the stack is |
1092 | to use the macros: |
1093 | |
1094 | XPUSHi(IV) |
1095 | XPUSHn(double) |
1096 | XPUSHp(char*, I32) |
1097 | XPUSHs(SV*) |
1098 | |
1099 | These macros automatically adjust the stack for you, if needed. Thus, you |
1100 | do not need to call C<EXTEND> to extend the stack. |
1101 | |
1102 | For more information, consult L<perlxs> and L<perlxstut>. |
1103 | |
1104 | =head2 Calling Perl Routines from within C Programs |
a0d0e21e |
1105 | |
1106 | There are four routines that can be used to call a Perl subroutine from |
1107 | within a C program. These four are: |
1108 | |
1109 | I32 perl_call_sv(SV*, I32); |
1110 | I32 perl_call_pv(char*, I32); |
1111 | I32 perl_call_method(char*, I32); |
1112 | I32 perl_call_argv(char*, I32, register char**); |
1113 | |
d1b91892 |
1114 | The routine most often used is C<perl_call_sv>. The C<SV*> argument |
1115 | contains either the name of the Perl subroutine to be called, or a |
1116 | reference to the subroutine. The second argument consists of flags |
1117 | that control the context in which the subroutine is called, whether |
1118 | or not the subroutine is being passed arguments, how errors should be |
1119 | trapped, and how to treat return values. |
a0d0e21e |
1120 | |
1121 | All four routines return the number of arguments that the subroutine returned |
1122 | on the Perl stack. |
1123 | |
d1b91892 |
1124 | When using any of these routines (except C<perl_call_argv>), the programmer |
1125 | must manipulate the Perl stack. These include the following macros and |
1126 | functions: |
a0d0e21e |
1127 | |
1128 | dSP |
1129 | PUSHMARK() |
1130 | PUTBACK |
1131 | SPAGAIN |
1132 | ENTER |
1133 | SAVETMPS |
1134 | FREETMPS |
1135 | LEAVE |
1136 | XPUSH*() |
cb1a09d0 |
1137 | POP*() |
a0d0e21e |
1138 | |
5f05dabc |
1139 | For a detailed description of calling conventions from C to Perl, |
1140 | consult L<perlcall>. |
a0d0e21e |
1141 | |
5f05dabc |
1142 | =head2 Memory Allocation |
a0d0e21e |
1143 | |
5f05dabc |
1144 | It is suggested that you use the version of malloc that is distributed |
1145 | with Perl. It keeps pools of various sizes of unallocated memory in |
07fa94a1 |
1146 | order to satisfy allocation requests more quickly. However, on some |
1147 | platforms, it may cause spurious malloc or free errors. |
d1b91892 |
1148 | |
1149 | New(x, pointer, number, type); |
1150 | Newc(x, pointer, number, type, cast); |
1151 | Newz(x, pointer, number, type); |
1152 | |
07fa94a1 |
1153 | These three macros are used to initially allocate memory. |
5f05dabc |
1154 | |
1155 | The first argument C<x> was a "magic cookie" that was used to keep track |
1156 | of who called the macro, to help when debugging memory problems. However, |
07fa94a1 |
1157 | the current code makes no use of this feature (most Perl developers now |
1158 | use run-time memory checkers), so this argument can be any number. |
5f05dabc |
1159 | |
1160 | The second argument C<pointer> should be the name of a variable that will |
1161 | point to the newly allocated memory. |
d1b91892 |
1162 | |
d1b91892 |
1163 | The third and fourth arguments C<number> and C<type> specify how many of |
1164 | the specified type of data structure should be allocated. The argument |
1165 | C<type> is passed to C<sizeof>. The final argument to C<Newc>, C<cast>, |
1166 | should be used if the C<pointer> argument is different from the C<type> |
1167 | argument. |
1168 | |
1169 | Unlike the C<New> and C<Newc> macros, the C<Newz> macro calls C<memzero> |
1170 | to zero out all the newly allocated memory. |
1171 | |
1172 | Renew(pointer, number, type); |
1173 | Renewc(pointer, number, type, cast); |
1174 | Safefree(pointer) |
1175 | |
1176 | These three macros are used to change a memory buffer size or to free a |
1177 | piece of memory no longer needed. The arguments to C<Renew> and C<Renewc> |
1178 | match those of C<New> and C<Newc> with the exception of not needing the |
1179 | "magic cookie" argument. |
1180 | |
1181 | Move(source, dest, number, type); |
1182 | Copy(source, dest, number, type); |
1183 | Zero(dest, number, type); |
1184 | |
1185 | These three macros are used to move, copy, or zero out previously allocated |
1186 | memory. The C<source> and C<dest> arguments point to the source and |
1187 | destination starting points. Perl will move, copy, or zero out C<number> |
1188 | instances of the size of the C<type> data structure (using the C<sizeof> |
1189 | function). |
a0d0e21e |
1190 | |
5f05dabc |
1191 | =head2 PerlIO |
ce3d39e2 |
1192 | |
5f05dabc |
1193 | The most recent development releases of Perl has been experimenting with |
1194 | removing Perl's dependency on the "normal" standard I/O suite and allowing |
1195 | other stdio implementations to be used. This involves creating a new |
1196 | abstraction layer that then calls whichever implementation of stdio Perl |
68dc0745 |
1197 | was compiled with. All XSUBs should now use the functions in the PerlIO |
5f05dabc |
1198 | abstraction layer and not make any assumptions about what kind of stdio |
1199 | is being used. |
1200 | |
1201 | For a complete description of the PerlIO abstraction, consult L<perlapio>. |
1202 | |
8ebc5c01 |
1203 | =head2 Putting a C value on Perl stack |
ce3d39e2 |
1204 | |
1205 | A lot of opcodes (this is an elementary operation in the internal perl |
1206 | stack machine) put an SV* on the stack. However, as an optimization |
1207 | the corresponding SV is (usually) not recreated each time. The opcodes |
1208 | reuse specially assigned SVs (I<target>s) which are (as a corollary) |
1209 | not constantly freed/created. |
1210 | |
0a753a76 |
1211 | Each of the targets is created only once (but see |
ce3d39e2 |
1212 | L<Scratchpads and recursion> below), and when an opcode needs to put |
1213 | an integer, a double, or a string on stack, it just sets the |
1214 | corresponding parts of its I<target> and puts the I<target> on stack. |
1215 | |
1216 | The macro to put this target on stack is C<PUSHTARG>, and it is |
1217 | directly used in some opcodes, as well as indirectly in zillions of |
1218 | others, which use it via C<(X)PUSH[pni]>. |
1219 | |
8ebc5c01 |
1220 | =head2 Scratchpads |
ce3d39e2 |
1221 | |
54310121 |
1222 | The question remains on when the SVs which are I<target>s for opcodes |
5f05dabc |
1223 | are created. The answer is that they are created when the current unit -- |
1224 | a subroutine or a file (for opcodes for statements outside of |
1225 | subroutines) -- is compiled. During this time a special anonymous Perl |
ce3d39e2 |
1226 | array is created, which is called a scratchpad for the current |
1227 | unit. |
1228 | |
54310121 |
1229 | A scratchpad keeps SVs which are lexicals for the current unit and are |
ce3d39e2 |
1230 | targets for opcodes. One can deduce that an SV lives on a scratchpad |
1231 | by looking on its flags: lexicals have C<SVs_PADMY> set, and |
1232 | I<target>s have C<SVs_PADTMP> set. |
1233 | |
54310121 |
1234 | The correspondence between OPs and I<target>s is not 1-to-1. Different |
1235 | OPs in the compile tree of the unit can use the same target, if this |
ce3d39e2 |
1236 | would not conflict with the expected life of the temporary. |
1237 | |
2ae324a7 |
1238 | =head2 Scratchpads and recursion |
ce3d39e2 |
1239 | |
1240 | In fact it is not 100% true that a compiled unit contains a pointer to |
1241 | the scratchpad AV. In fact it contains a pointer to an AV of |
1242 | (initially) one element, and this element is the scratchpad AV. Why do |
1243 | we need an extra level of indirection? |
1244 | |
1245 | The answer is B<recursion>, and maybe (sometime soon) B<threads>. Both |
1246 | these can create several execution pointers going into the same |
1247 | subroutine. For the subroutine-child not write over the temporaries |
1248 | for the subroutine-parent (lifespan of which covers the call to the |
1249 | child), the parent and the child should have different |
1250 | scratchpads. (I<And> the lexicals should be separate anyway!) |
1251 | |
5f05dabc |
1252 | So each subroutine is born with an array of scratchpads (of length 1). |
1253 | On each entry to the subroutine it is checked that the current |
ce3d39e2 |
1254 | depth of the recursion is not more than the length of this array, and |
1255 | if it is, new scratchpad is created and pushed into the array. |
1256 | |
1257 | The I<target>s on this scratchpad are C<undef>s, but they are already |
1258 | marked with correct flags. |
1259 | |
0a753a76 |
1260 | =head1 Compiled code |
1261 | |
1262 | =head2 Code tree |
1263 | |
1264 | Here we describe the internal form your code is converted to by |
1265 | Perl. Start with a simple example: |
1266 | |
1267 | $a = $b + $c; |
1268 | |
1269 | This is converted to a tree similar to this one: |
1270 | |
1271 | assign-to |
1272 | / \ |
1273 | + $a |
1274 | / \ |
1275 | $b $c |
1276 | |
1277 | (but slightly more complicated). This tree reflect the way Perl |
1278 | parsed your code, but has nothing to do with the execution order. |
1279 | There is an additional "thread" going through the nodes of the tree |
1280 | which shows the order of execution of the nodes. In our simplified |
1281 | example above it looks like: |
1282 | |
1283 | $b ---> $c ---> + ---> $a ---> assign-to |
1284 | |
1285 | But with the actual compile tree for C<$a = $b + $c> it is different: |
1286 | some nodes I<optimized away>. As a corollary, though the actual tree |
1287 | contains more nodes than our simplified example, the execution order |
1288 | is the same as in our example. |
1289 | |
1290 | =head2 Examining the tree |
1291 | |
1292 | If you have your perl compiled for debugging (usually done with C<-D |
1293 | optimize=-g> on C<Configure> command line), you may examine the |
1294 | compiled tree by specifying C<-Dx> on the Perl command line. The |
1295 | output takes several lines per node, and for C<$b+$c> it looks like |
1296 | this: |
1297 | |
1298 | 5 TYPE = add ===> 6 |
1299 | TARG = 1 |
1300 | FLAGS = (SCALAR,KIDS) |
1301 | { |
1302 | TYPE = null ===> (4) |
1303 | (was rv2sv) |
1304 | FLAGS = (SCALAR,KIDS) |
1305 | { |
1306 | 3 TYPE = gvsv ===> 4 |
1307 | FLAGS = (SCALAR) |
1308 | GV = main::b |
1309 | } |
1310 | } |
1311 | { |
1312 | TYPE = null ===> (5) |
1313 | (was rv2sv) |
1314 | FLAGS = (SCALAR,KIDS) |
1315 | { |
1316 | 4 TYPE = gvsv ===> 5 |
1317 | FLAGS = (SCALAR) |
1318 | GV = main::c |
1319 | } |
1320 | } |
1321 | |
1322 | This tree has 5 nodes (one per C<TYPE> specifier), only 3 of them are |
1323 | not optimized away (one per number in the left column). The immediate |
1324 | children of the given node correspond to C<{}> pairs on the same level |
1325 | of indentation, thus this listing corresponds to the tree: |
1326 | |
1327 | add |
1328 | / \ |
1329 | null null |
1330 | | | |
1331 | gvsv gvsv |
1332 | |
1333 | The execution order is indicated by C<===E<gt>> marks, thus it is C<3 |
1334 | 4 5 6> (node C<6> is not included into above listing), i.e., |
1335 | C<gvsv gvsv add whatever>. |
1336 | |
1337 | =head2 Compile pass 1: check routines |
1338 | |
1339 | The tree is created by the I<pseudo-compiler> while yacc code feeds it |
1340 | the constructions it recognizes. Since yacc works bottom-up, so does |
1341 | the first pass of perl compilation. |
1342 | |
1343 | What makes this pass interesting for perl developers is that some |
1344 | optimization may be performed on this pass. This is optimization by |
1345 | so-called I<check routines>. The correspondence between node names |
1346 | and corresponding check routines is described in F<opcode.pl> (do not |
1347 | forget to run C<make regen_headers> if you modify this file). |
1348 | |
1349 | A check routine is called when the node is fully constructed except |
1350 | for the execution-order thread. Since at this time there is no |
1351 | back-links to the currently constructed node, one can do most any |
1352 | operation to the top-level node, including freeing it and/or creating |
1353 | new nodes above/below it. |
1354 | |
1355 | The check routine returns the node which should be inserted into the |
1356 | tree (if the top-level node was not modified, check routine returns |
1357 | its argument). |
1358 | |
1359 | By convention, check routines have names C<ck_*>. They are usually |
1360 | called from C<new*OP> subroutines (or C<convert>) (which in turn are |
1361 | called from F<perly.y>). |
1362 | |
1363 | =head2 Compile pass 1a: constant folding |
1364 | |
1365 | Immediately after the check routine is called the returned node is |
1366 | checked for being compile-time executable. If it is (the value is |
1367 | judged to be constant) it is immediately executed, and a I<constant> |
1368 | node with the "return value" of the corresponding subtree is |
1369 | substituted instead. The subtree is deleted. |
1370 | |
1371 | If constant folding was not performed, the execution-order thread is |
1372 | created. |
1373 | |
1374 | =head2 Compile pass 2: context propagation |
1375 | |
1376 | When a context for a part of compile tree is known, it is propagated |
1377 | down through the tree. Aat this time the context can have 5 values |
1378 | (instead of 2 for runtime context): void, boolean, scalar, list, and |
1379 | lvalue. In contrast with the pass 1 this pass is processed from top |
1380 | to bottom: a node's context determines the context for its children. |
1381 | |
1382 | Additional context-dependent optimizations are performed at this time. |
1383 | Since at this moment the compile tree contains back-references (via |
1384 | "thread" pointers), nodes cannot be free()d now. To allow |
1385 | optimized-away nodes at this stage, such nodes are null()ified instead |
1386 | of free()ing (i.e. their type is changed to OP_NULL). |
1387 | |
1388 | =head2 Compile pass 3: peephole optimization |
1389 | |
1390 | After the compile tree for a subroutine (or for an C<eval> or a file) |
1391 | is created, an additional pass over the code is performed. This pass |
1392 | is neither top-down or bottom-up, but in the execution order (with |
1393 | additional compilications for conditionals). These optimizations are |
1394 | done in the subroutine peep(). Optimizations performed at this stage |
1395 | are subject to the same restrictions as in the pass 2. |
1396 | |
1397 | =head1 API LISTING |
a0d0e21e |
1398 | |
cb1a09d0 |
1399 | This is a listing of functions, macros, flags, and variables that may be |
1400 | useful to extension writers or that may be found while reading other |
1401 | extensions. |
a0d0e21e |
1402 | |
cb1a09d0 |
1403 | =over 8 |
a0d0e21e |
1404 | |
cb1a09d0 |
1405 | =item AvFILL |
1406 | |
1407 | See C<av_len>. |
1408 | |
1409 | =item av_clear |
1410 | |
0146554f |
1411 | Clears an array, making it empty. Does not free the memory used by the |
1412 | array itself. |
cb1a09d0 |
1413 | |
1414 | void av_clear _((AV* ar)); |
1415 | |
1416 | =item av_extend |
1417 | |
1418 | Pre-extend an array. The C<key> is the index to which the array should be |
1419 | extended. |
1420 | |
1421 | void av_extend _((AV* ar, I32 key)); |
1422 | |
1423 | =item av_fetch |
1424 | |
1425 | Returns the SV at the specified index in the array. The C<key> is the |
1426 | index. If C<lval> is set then the fetch will be part of a store. Check |
1427 | that the return value is non-null before dereferencing it to a C<SV*>. |
1428 | |
04343c6d |
1429 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1430 | information on how to use this function on tied arrays. |
1431 | |
cb1a09d0 |
1432 | SV** av_fetch _((AV* ar, I32 key, I32 lval)); |
1433 | |
1434 | =item av_len |
1435 | |
1436 | Returns the highest index in the array. Returns -1 if the array is empty. |
1437 | |
1438 | I32 av_len _((AV* ar)); |
1439 | |
1440 | =item av_make |
1441 | |
5fb8527f |
1442 | Creates a new AV and populates it with a list of SVs. The SVs are copied |
1443 | into the array, so they may be freed after the call to av_make. The new AV |
5f05dabc |
1444 | will have a reference count of 1. |
cb1a09d0 |
1445 | |
1446 | AV* av_make _((I32 size, SV** svp)); |
1447 | |
1448 | =item av_pop |
1449 | |
1450 | Pops an SV off the end of the array. Returns C<&sv_undef> if the array is |
1451 | empty. |
1452 | |
1453 | SV* av_pop _((AV* ar)); |
1454 | |
1455 | =item av_push |
1456 | |
5fb8527f |
1457 | Pushes an SV onto the end of the array. The array will grow automatically |
1458 | to accommodate the addition. |
cb1a09d0 |
1459 | |
1460 | void av_push _((AV* ar, SV* val)); |
1461 | |
1462 | =item av_shift |
1463 | |
1464 | Shifts an SV off the beginning of the array. |
1465 | |
1466 | SV* av_shift _((AV* ar)); |
1467 | |
1468 | =item av_store |
1469 | |
1470 | Stores an SV in an array. The array index is specified as C<key>. The |
04343c6d |
1471 | return value will be NULL if the operation failed or if the value did not |
1472 | need to be actually stored within the array (as in the case of tied arrays). |
1473 | Otherwise it can be dereferenced to get the original C<SV*>. Note that the |
1474 | caller is responsible for suitably incrementing the reference count of C<val> |
1475 | before the call, and decrementing it if the function returned NULL. |
1476 | |
1477 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1478 | information on how to use this function on tied arrays. |
cb1a09d0 |
1479 | |
1480 | SV** av_store _((AV* ar, I32 key, SV* val)); |
1481 | |
1482 | =item av_undef |
1483 | |
0146554f |
1484 | Undefines the array. Frees the memory used by the array itself. |
cb1a09d0 |
1485 | |
1486 | void av_undef _((AV* ar)); |
1487 | |
1488 | =item av_unshift |
1489 | |
0146554f |
1490 | Unshift the given number of C<undef> values onto the beginning of the |
1491 | array. The array will grow automatically to accommodate the addition. |
1492 | You must then use C<av_store> to assign values to these new elements. |
cb1a09d0 |
1493 | |
1494 | void av_unshift _((AV* ar, I32 num)); |
1495 | |
1496 | =item CLASS |
1497 | |
1498 | Variable which is setup by C<xsubpp> to indicate the class name for a C++ XS |
5fb8527f |
1499 | constructor. This is always a C<char*>. See C<THIS> and |
1500 | L<perlxs/"Using XS With C++">. |
cb1a09d0 |
1501 | |
1502 | =item Copy |
1503 | |
1504 | The XSUB-writer's interface to the C C<memcpy> function. The C<s> is the |
1505 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
0146554f |
1506 | the type. May fail on overlapping copies. See also C<Move>. |
cb1a09d0 |
1507 | |
1508 | (void) Copy( s, d, n, t ); |
1509 | |
1510 | =item croak |
1511 | |
1512 | This is the XSUB-writer's interface to Perl's C<die> function. Use this |
1513 | function the same way you use the C C<printf> function. See C<warn>. |
1514 | |
1515 | =item CvSTASH |
1516 | |
1517 | Returns the stash of the CV. |
1518 | |
1519 | HV * CvSTASH( SV* sv ) |
1520 | |
1521 | =item DBsingle |
1522 | |
1523 | When Perl is run in debugging mode, with the B<-d> switch, this SV is a |
1524 | boolean which indicates whether subs are being single-stepped. |
5fb8527f |
1525 | Single-stepping is automatically turned on after every step. This is the C |
1526 | variable which corresponds to Perl's $DB::single variable. See C<DBsub>. |
cb1a09d0 |
1527 | |
1528 | =item DBsub |
1529 | |
1530 | When Perl is run in debugging mode, with the B<-d> switch, this GV contains |
5fb8527f |
1531 | the SV which holds the name of the sub being debugged. This is the C |
1532 | variable which corresponds to Perl's $DB::sub variable. See C<DBsingle>. |
cb1a09d0 |
1533 | The sub name can be found by |
1534 | |
1535 | SvPV( GvSV( DBsub ), na ) |
1536 | |
5fb8527f |
1537 | =item DBtrace |
1538 | |
1539 | Trace variable used when Perl is run in debugging mode, with the B<-d> |
1540 | switch. This is the C variable which corresponds to Perl's $DB::trace |
1541 | variable. See C<DBsingle>. |
1542 | |
cb1a09d0 |
1543 | =item dMARK |
1544 | |
5fb8527f |
1545 | Declare a stack marker variable, C<mark>, for the XSUB. See C<MARK> and |
1546 | C<dORIGMARK>. |
cb1a09d0 |
1547 | |
1548 | =item dORIGMARK |
1549 | |
1550 | Saves the original stack mark for the XSUB. See C<ORIGMARK>. |
1551 | |
5fb8527f |
1552 | =item dowarn |
1553 | |
1554 | The C variable which corresponds to Perl's $^W warning variable. |
1555 | |
cb1a09d0 |
1556 | =item dSP |
1557 | |
5fb8527f |
1558 | Declares a stack pointer variable, C<sp>, for the XSUB. See C<SP>. |
cb1a09d0 |
1559 | |
1560 | =item dXSARGS |
1561 | |
1562 | Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is |
1563 | usually handled automatically by C<xsubpp>. Declares the C<items> variable |
1564 | to indicate the number of items on the stack. |
1565 | |
5fb8527f |
1566 | =item dXSI32 |
1567 | |
1568 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually |
1569 | handled automatically by C<xsubpp>. |
1570 | |
cb1a09d0 |
1571 | =item ENTER |
1572 | |
1573 | Opening bracket on a callback. See C<LEAVE> and L<perlcall>. |
1574 | |
1575 | ENTER; |
1576 | |
1577 | =item EXTEND |
1578 | |
1579 | Used to extend the argument stack for an XSUB's return values. |
1580 | |
1581 | EXTEND( sp, int x ); |
1582 | |
1583 | =item FREETMPS |
1584 | |
1585 | Closing bracket for temporaries on a callback. See C<SAVETMPS> and |
1586 | L<perlcall>. |
1587 | |
1588 | FREETMPS; |
1589 | |
1590 | =item G_ARRAY |
1591 | |
54310121 |
1592 | Used to indicate array context. See C<GIMME_V>, C<GIMME> and L<perlcall>. |
cb1a09d0 |
1593 | |
1594 | =item G_DISCARD |
1595 | |
1596 | Indicates that arguments returned from a callback should be discarded. See |
1597 | L<perlcall>. |
1598 | |
1599 | =item G_EVAL |
1600 | |
1601 | Used to force a Perl C<eval> wrapper around a callback. See L<perlcall>. |
1602 | |
1603 | =item GIMME |
1604 | |
54310121 |
1605 | A backward-compatible version of C<GIMME_V> which can only return |
1606 | C<G_SCALAR> or C<G_ARRAY>; in a void context, it returns C<G_SCALAR>. |
1607 | |
1608 | =item GIMME_V |
1609 | |
1610 | The XSUB-writer's equivalent to Perl's C<wantarray>. Returns |
1611 | C<G_VOID>, C<G_SCALAR> or C<G_ARRAY> for void, scalar or array |
1612 | context, respectively. |
cb1a09d0 |
1613 | |
1614 | =item G_NOARGS |
1615 | |
1616 | Indicates that no arguments are being sent to a callback. See L<perlcall>. |
1617 | |
1618 | =item G_SCALAR |
1619 | |
54310121 |
1620 | Used to indicate scalar context. See C<GIMME_V>, C<GIMME>, and L<perlcall>. |
1621 | |
1622 | =item G_VOID |
1623 | |
1624 | Used to indicate void context. See C<GIMME_V> and L<perlcall>. |
cb1a09d0 |
1625 | |
faed5253 |
1626 | =item gv_fetchmeth |
1627 | |
1628 | Returns the glob with the given C<name> and a defined subroutine or |
9607fc9c |
1629 | C<NULL>. The glob lives in the given C<stash>, or in the stashes |
1630 | accessable via @ISA and @<UNIVERSAL>. |
faed5253 |
1631 | |
9607fc9c |
1632 | The argument C<level> should be either 0 or -1. If C<level==0>, as a |
0a753a76 |
1633 | side-effect creates a glob with the given C<name> in the given |
1634 | C<stash> which in the case of success contains an alias for the |
1635 | subroutine, and sets up caching info for this glob. Similarly for all |
1636 | the searched stashes. |
1637 | |
9607fc9c |
1638 | This function grants C<"SUPER"> token as a postfix of the stash name. |
1639 | |
0a753a76 |
1640 | The GV returned from C<gv_fetchmeth> may be a method cache entry, |
1641 | which is not visible to Perl code. So when calling C<perl_call_sv>, |
1642 | you should not use the GV directly; instead, you should use the |
1643 | method's CV, which can be obtained from the GV with the C<GvCV> macro. |
faed5253 |
1644 | |
1645 | GV* gv_fetchmeth _((HV* stash, char* name, STRLEN len, I32 level)); |
1646 | |
1647 | =item gv_fetchmethod |
1648 | |
dc848c6f |
1649 | =item gv_fetchmethod_autoload |
1650 | |
faed5253 |
1651 | Returns the glob which contains the subroutine to call to invoke the |
dc848c6f |
1652 | method on the C<stash>. In fact in the presense of autoloading this may |
1653 | be the glob for "AUTOLOAD". In this case the corresponding variable |
faed5253 |
1654 | $AUTOLOAD is already setup. |
1655 | |
dc848c6f |
1656 | The third parameter of C<gv_fetchmethod_autoload> determines whether AUTOLOAD |
1657 | lookup is performed if the given method is not present: non-zero means |
1658 | yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling |
1659 | C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload> with a |
1660 | non-zero C<autoload> parameter. |
1661 | |
1662 | These functions grant C<"SUPER"> token as a prefix of the method name. |
1663 | |
1664 | Note that if you want to keep the returned glob for a long time, you |
1665 | need to check for it being "AUTOLOAD", since at the later time the call |
faed5253 |
1666 | may load a different subroutine due to $AUTOLOAD changing its value. |
1667 | Use the glob created via a side effect to do this. |
1668 | |
dc848c6f |
1669 | These functions have the same side-effects and as C<gv_fetchmeth> with |
1670 | C<level==0>. C<name> should be writable if contains C<':'> or C<'\''>. |
0a753a76 |
1671 | The warning against passing the GV returned by C<gv_fetchmeth> to |
dc848c6f |
1672 | C<perl_call_sv> apply equally to these functions. |
faed5253 |
1673 | |
1674 | GV* gv_fetchmethod _((HV* stash, char* name)); |
dc848c6f |
1675 | GV* gv_fetchmethod_autoload _((HV* stash, char* name, |
1676 | I32 autoload)); |
faed5253 |
1677 | |
cb1a09d0 |
1678 | =item gv_stashpv |
1679 | |
1680 | Returns a pointer to the stash for a specified package. If C<create> is set |
1681 | then the package will be created if it does not already exist. If C<create> |
1682 | is not set and the package does not exist then NULL is returned. |
1683 | |
1684 | HV* gv_stashpv _((char* name, I32 create)); |
1685 | |
1686 | =item gv_stashsv |
1687 | |
1688 | Returns a pointer to the stash for a specified package. See C<gv_stashpv>. |
1689 | |
1690 | HV* gv_stashsv _((SV* sv, I32 create)); |
1691 | |
e5581bf4 |
1692 | =item GvSV |
cb1a09d0 |
1693 | |
e5581bf4 |
1694 | Return the SV from the GV. |
44a8e56a |
1695 | |
1e422769 |
1696 | =item HEf_SVKEY |
1697 | |
1698 | This flag, used in the length slot of hash entries and magic |
1699 | structures, specifies the structure contains a C<SV*> pointer where a |
1700 | C<char*> pointer is to be expected. (For information only--not to be used). |
1701 | |
1e422769 |
1702 | =item HeHASH |
1703 | |
1704 | Returns the computed hash (type C<U32>) stored in the hash entry. |
1705 | |
1706 | HeHASH(HE* he) |
1707 | |
1708 | =item HeKEY |
1709 | |
1710 | Returns the actual pointer stored in the key slot of the hash entry. |
1711 | The pointer may be either C<char*> or C<SV*>, depending on the value of |
1712 | C<HeKLEN()>. Can be assigned to. The C<HePV()> or C<HeSVKEY()> macros |
1713 | are usually preferable for finding the value of a key. |
1714 | |
1715 | HeKEY(HE* he) |
1716 | |
1717 | =item HeKLEN |
1718 | |
1719 | If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry |
1720 | holds an C<SV*> key. Otherwise, holds the actual length of the key. |
1721 | Can be assigned to. The C<HePV()> macro is usually preferable for finding |
1722 | key lengths. |
1723 | |
1724 | HeKLEN(HE* he) |
1725 | |
1726 | =item HePV |
1727 | |
1728 | Returns the key slot of the hash entry as a C<char*> value, doing any |
1729 | necessary dereferencing of possibly C<SV*> keys. The length of |
1730 | the string is placed in C<len> (this is a macro, so do I<not> use |
1731 | C<&len>). If you do not care about what the length of the key is, |
1732 | you may use the global variable C<na>. Remember though, that hash |
1733 | keys in perl are free to contain embedded nulls, so using C<strlen()> |
1734 | or similar is not a good way to find the length of hash keys. |
1735 | This is very similar to the C<SvPV()> macro described elsewhere in |
1736 | this document. |
1737 | |
1738 | HePV(HE* he, STRLEN len) |
1739 | |
1740 | =item HeSVKEY |
1741 | |
1742 | Returns the key as an C<SV*>, or C<Nullsv> if the hash entry |
1743 | does not contain an C<SV*> key. |
1744 | |
1745 | HeSVKEY(HE* he) |
1746 | |
1747 | =item HeSVKEY_force |
1748 | |
1749 | Returns the key as an C<SV*>. Will create and return a temporary |
1750 | mortal C<SV*> if the hash entry contains only a C<char*> key. |
1751 | |
1752 | HeSVKEY_force(HE* he) |
1753 | |
1754 | =item HeSVKEY_set |
1755 | |
1756 | Sets the key to a given C<SV*>, taking care to set the appropriate flags |
1757 | to indicate the presence of an C<SV*> key, and returns the same C<SV*>. |
1758 | |
1759 | HeSVKEY_set(HE* he, SV* sv) |
1760 | |
1761 | =item HeVAL |
1762 | |
1763 | Returns the value slot (type C<SV*>) stored in the hash entry. |
1764 | |
1765 | HeVAL(HE* he) |
1766 | |
cb1a09d0 |
1767 | =item hv_clear |
1768 | |
1769 | Clears a hash, making it empty. |
1770 | |
1771 | void hv_clear _((HV* tb)); |
1772 | |
68dc0745 |
1773 | =item hv_delayfree_ent |
1774 | |
1775 | Releases a hash entry, such as while iterating though the hash, but |
1776 | delays actual freeing of key and value until the end of the current |
1777 | statement (or thereabouts) with C<sv_2mortal>. See C<hv_iternext> |
1778 | and C<hv_free_ent>. |
1779 | |
1780 | void hv_delayfree_ent _((HV* hv, HE* entry)); |
1781 | |
cb1a09d0 |
1782 | =item hv_delete |
1783 | |
1784 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
5fb8527f |
1785 | and returned to the caller. The C<klen> is the length of the key. The |
04343c6d |
1786 | C<flags> value will normally be zero; if set to G_DISCARD then NULL will be |
cb1a09d0 |
1787 | returned. |
1788 | |
1789 | SV* hv_delete _((HV* tb, char* key, U32 klen, I32 flags)); |
1790 | |
1e422769 |
1791 | =item hv_delete_ent |
1792 | |
1793 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
1794 | and returned to the caller. The C<flags> value will normally be zero; if set |
04343c6d |
1795 | to G_DISCARD then NULL will be returned. C<hash> can be a valid precomputed |
1e422769 |
1796 | hash value, or 0 to ask for it to be computed. |
1797 | |
1798 | SV* hv_delete_ent _((HV* tb, SV* key, I32 flags, U32 hash)); |
1799 | |
cb1a09d0 |
1800 | =item hv_exists |
1801 | |
1802 | Returns a boolean indicating whether the specified hash key exists. The |
5fb8527f |
1803 | C<klen> is the length of the key. |
cb1a09d0 |
1804 | |
1805 | bool hv_exists _((HV* tb, char* key, U32 klen)); |
1806 | |
1e422769 |
1807 | =item hv_exists_ent |
1808 | |
1809 | Returns a boolean indicating whether the specified hash key exists. C<hash> |
54310121 |
1810 | can be a valid precomputed hash value, or 0 to ask for it to be computed. |
1e422769 |
1811 | |
1812 | bool hv_exists_ent _((HV* tb, SV* key, U32 hash)); |
1813 | |
cb1a09d0 |
1814 | =item hv_fetch |
1815 | |
1816 | Returns the SV which corresponds to the specified key in the hash. The |
5fb8527f |
1817 | C<klen> is the length of the key. If C<lval> is set then the fetch will be |
cb1a09d0 |
1818 | part of a store. Check that the return value is non-null before |
1819 | dereferencing it to a C<SV*>. |
1820 | |
04343c6d |
1821 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1822 | information on how to use this function on tied hashes. |
1823 | |
cb1a09d0 |
1824 | SV** hv_fetch _((HV* tb, char* key, U32 klen, I32 lval)); |
1825 | |
1e422769 |
1826 | =item hv_fetch_ent |
1827 | |
1828 | Returns the hash entry which corresponds to the specified key in the hash. |
54310121 |
1829 | C<hash> must be a valid precomputed hash number for the given C<key>, or |
1e422769 |
1830 | 0 if you want the function to compute it. IF C<lval> is set then the |
1831 | fetch will be part of a store. Make sure the return value is non-null |
1832 | before accessing it. The return value when C<tb> is a tied hash |
1833 | is a pointer to a static location, so be sure to make a copy of the |
1834 | structure if you need to store it somewhere. |
1835 | |
04343c6d |
1836 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1837 | information on how to use this function on tied hashes. |
1838 | |
1e422769 |
1839 | HE* hv_fetch_ent _((HV* tb, SV* key, I32 lval, U32 hash)); |
1840 | |
68dc0745 |
1841 | =item hv_free_ent |
1842 | |
1843 | Releases a hash entry, such as while iterating though the hash. See |
1844 | C<hv_iternext> and C<hv_delayfree_ent>. |
1845 | |
1846 | void hv_free_ent _((HV* hv, HE* entry)); |
1847 | |
cb1a09d0 |
1848 | =item hv_iterinit |
1849 | |
1850 | Prepares a starting point to traverse a hash table. |
1851 | |
1852 | I32 hv_iterinit _((HV* tb)); |
1853 | |
1854 | =item hv_iterkey |
1855 | |
1856 | Returns the key from the current position of the hash iterator. See |
1857 | C<hv_iterinit>. |
1858 | |
1859 | char* hv_iterkey _((HE* entry, I32* retlen)); |
1860 | |
1e422769 |
1861 | =item hv_iterkeysv |
3fe9a6f1 |
1862 | |
1e422769 |
1863 | Returns the key as an C<SV*> from the current position of the hash |
1864 | iterator. The return value will always be a mortal copy of the |
1865 | key. Also see C<hv_iterinit>. |
1866 | |
1867 | SV* hv_iterkeysv _((HE* entry)); |
1868 | |
cb1a09d0 |
1869 | =item hv_iternext |
1870 | |
1871 | Returns entries from a hash iterator. See C<hv_iterinit>. |
1872 | |
1873 | HE* hv_iternext _((HV* tb)); |
1874 | |
1875 | =item hv_iternextsv |
1876 | |
1877 | Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one |
1878 | operation. |
1879 | |
1880 | SV * hv_iternextsv _((HV* hv, char** key, I32* retlen)); |
1881 | |
1882 | =item hv_iterval |
1883 | |
1884 | Returns the value from the current position of the hash iterator. See |
1885 | C<hv_iterkey>. |
1886 | |
1887 | SV* hv_iterval _((HV* tb, HE* entry)); |
1888 | |
1889 | =item hv_magic |
1890 | |
1891 | Adds magic to a hash. See C<sv_magic>. |
1892 | |
1893 | void hv_magic _((HV* hv, GV* gv, int how)); |
1894 | |
1895 | =item HvNAME |
1896 | |
1897 | Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>. |
1898 | |
1899 | char *HvNAME (HV* stash) |
1900 | |
1901 | =item hv_store |
1902 | |
1903 | Stores an SV in a hash. The hash key is specified as C<key> and C<klen> is |
54310121 |
1904 | the length of the key. The C<hash> parameter is the precomputed hash |
cb1a09d0 |
1905 | value; if it is zero then Perl will compute it. The return value will be |
04343c6d |
1906 | NULL if the operation failed or if the value did not need to be actually |
1907 | stored within the hash (as in the case of tied hashes). Otherwise it can |
1908 | be dereferenced to get the original C<SV*>. Note that the caller is |
1909 | responsible for suitably incrementing the reference count of C<val> |
1910 | before the call, and decrementing it if the function returned NULL. |
1911 | |
1912 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1913 | information on how to use this function on tied hashes. |
cb1a09d0 |
1914 | |
1915 | SV** hv_store _((HV* tb, char* key, U32 klen, SV* val, U32 hash)); |
1916 | |
1e422769 |
1917 | =item hv_store_ent |
1918 | |
1919 | Stores C<val> in a hash. The hash key is specified as C<key>. The C<hash> |
54310121 |
1920 | parameter is the precomputed hash value; if it is zero then Perl will |
1e422769 |
1921 | compute it. The return value is the new hash entry so created. It will be |
04343c6d |
1922 | NULL if the operation failed or if the value did not need to be actually |
1923 | stored within the hash (as in the case of tied hashes). Otherwise the |
1924 | contents of the return value can be accessed using the C<He???> macros |
1925 | described here. Note that the caller is responsible for suitably |
1926 | incrementing the reference count of C<val> before the call, and decrementing |
1927 | it if the function returned NULL. |
1928 | |
1929 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1930 | information on how to use this function on tied hashes. |
1e422769 |
1931 | |
1932 | HE* hv_store_ent _((HV* tb, SV* key, SV* val, U32 hash)); |
1933 | |
cb1a09d0 |
1934 | =item hv_undef |
1935 | |
1936 | Undefines the hash. |
1937 | |
1938 | void hv_undef _((HV* tb)); |
1939 | |
1940 | =item isALNUM |
1941 | |
1942 | Returns a boolean indicating whether the C C<char> is an ascii alphanumeric |
5f05dabc |
1943 | character or digit. |
cb1a09d0 |
1944 | |
1945 | int isALNUM (char c) |
1946 | |
1947 | =item isALPHA |
1948 | |
5fb8527f |
1949 | Returns a boolean indicating whether the C C<char> is an ascii alphabetic |
cb1a09d0 |
1950 | character. |
1951 | |
1952 | int isALPHA (char c) |
1953 | |
1954 | =item isDIGIT |
1955 | |
1956 | Returns a boolean indicating whether the C C<char> is an ascii digit. |
1957 | |
1958 | int isDIGIT (char c) |
1959 | |
1960 | =item isLOWER |
1961 | |
1962 | Returns a boolean indicating whether the C C<char> is a lowercase character. |
1963 | |
1964 | int isLOWER (char c) |
1965 | |
1966 | =item isSPACE |
1967 | |
1968 | Returns a boolean indicating whether the C C<char> is whitespace. |
1969 | |
1970 | int isSPACE (char c) |
1971 | |
1972 | =item isUPPER |
1973 | |
1974 | Returns a boolean indicating whether the C C<char> is an uppercase character. |
1975 | |
1976 | int isUPPER (char c) |
1977 | |
1978 | =item items |
1979 | |
1980 | Variable which is setup by C<xsubpp> to indicate the number of items on the |
5fb8527f |
1981 | stack. See L<perlxs/"Variable-length Parameter Lists">. |
1982 | |
1983 | =item ix |
1984 | |
1985 | Variable which is setup by C<xsubpp> to indicate which of an XSUB's aliases |
1986 | was used to invoke it. See L<perlxs/"The ALIAS: Keyword">. |
cb1a09d0 |
1987 | |
1988 | =item LEAVE |
1989 | |
1990 | Closing bracket on a callback. See C<ENTER> and L<perlcall>. |
1991 | |
1992 | LEAVE; |
1993 | |
1994 | =item MARK |
1995 | |
5fb8527f |
1996 | Stack marker variable for the XSUB. See C<dMARK>. |
cb1a09d0 |
1997 | |
1998 | =item mg_clear |
1999 | |
2000 | Clear something magical that the SV represents. See C<sv_magic>. |
2001 | |
2002 | int mg_clear _((SV* sv)); |
2003 | |
2004 | =item mg_copy |
2005 | |
2006 | Copies the magic from one SV to another. See C<sv_magic>. |
2007 | |
2008 | int mg_copy _((SV *, SV *, char *, STRLEN)); |
2009 | |
2010 | =item mg_find |
2011 | |
2012 | Finds the magic pointer for type matching the SV. See C<sv_magic>. |
2013 | |
2014 | MAGIC* mg_find _((SV* sv, int type)); |
2015 | |
2016 | =item mg_free |
2017 | |
2018 | Free any magic storage used by the SV. See C<sv_magic>. |
2019 | |
2020 | int mg_free _((SV* sv)); |
2021 | |
2022 | =item mg_get |
2023 | |
2024 | Do magic after a value is retrieved from the SV. See C<sv_magic>. |
2025 | |
2026 | int mg_get _((SV* sv)); |
2027 | |
2028 | =item mg_len |
2029 | |
2030 | Report on the SV's length. See C<sv_magic>. |
2031 | |
2032 | U32 mg_len _((SV* sv)); |
2033 | |
2034 | =item mg_magical |
2035 | |
2036 | Turns on the magical status of an SV. See C<sv_magic>. |
2037 | |
2038 | void mg_magical _((SV* sv)); |
2039 | |
2040 | =item mg_set |
2041 | |
2042 | Do magic after a value is assigned to the SV. See C<sv_magic>. |
2043 | |
2044 | int mg_set _((SV* sv)); |
2045 | |
2046 | =item Move |
2047 | |
2048 | The XSUB-writer's interface to the C C<memmove> function. The C<s> is the |
2049 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
0146554f |
2050 | the type. Can do overlapping moves. See also C<Copy>. |
cb1a09d0 |
2051 | |
2052 | (void) Move( s, d, n, t ); |
2053 | |
2054 | =item na |
2055 | |
2056 | A variable which may be used with C<SvPV> to tell Perl to calculate the |
2057 | string length. |
2058 | |
2059 | =item New |
2060 | |
2061 | The XSUB-writer's interface to the C C<malloc> function. |
2062 | |
2063 | void * New( x, void *ptr, int size, type ) |
2064 | |
2065 | =item Newc |
2066 | |
2067 | The XSUB-writer's interface to the C C<malloc> function, with cast. |
2068 | |
2069 | void * Newc( x, void *ptr, int size, type, cast ) |
2070 | |
2071 | =item Newz |
2072 | |
2073 | The XSUB-writer's interface to the C C<malloc> function. The allocated |
2074 | memory is zeroed with C<memzero>. |
2075 | |
2076 | void * Newz( x, void *ptr, int size, type ) |
2077 | |
2078 | =item newAV |
2079 | |
5f05dabc |
2080 | Creates a new AV. The reference count is set to 1. |
cb1a09d0 |
2081 | |
2082 | AV* newAV _((void)); |
2083 | |
2084 | =item newHV |
2085 | |
5f05dabc |
2086 | Creates a new HV. The reference count is set to 1. |
cb1a09d0 |
2087 | |
2088 | HV* newHV _((void)); |
2089 | |
5f05dabc |
2090 | =item newRV_inc |
cb1a09d0 |
2091 | |
5f05dabc |
2092 | Creates an RV wrapper for an SV. The reference count for the original SV is |
cb1a09d0 |
2093 | incremented. |
2094 | |
5f05dabc |
2095 | SV* newRV_inc _((SV* ref)); |
2096 | |
2097 | For historical reasons, "newRV" is a synonym for "newRV_inc". |
2098 | |
2099 | =item newRV_noinc |
2100 | |
2101 | Creates an RV wrapper for an SV. The reference count for the original |
2102 | SV is B<not> incremented. |
2103 | |
07fa94a1 |
2104 | SV* newRV_noinc _((SV* ref)); |
cb1a09d0 |
2105 | |
2106 | =item newSV |
2107 | |
2108 | Creates a new SV. The C<len> parameter indicates the number of bytes of |
68dc0745 |
2109 | preallocated string space the SV should have. The reference count for the |
07fa94a1 |
2110 | new SV is set to 1. |
cb1a09d0 |
2111 | |
2112 | SV* newSV _((STRLEN len)); |
2113 | |
2114 | =item newSViv |
2115 | |
07fa94a1 |
2116 | Creates a new SV and copies an integer into it. The reference count for the |
2117 | SV is set to 1. |
cb1a09d0 |
2118 | |
2119 | SV* newSViv _((IV i)); |
2120 | |
2121 | =item newSVnv |
2122 | |
07fa94a1 |
2123 | Creates a new SV and copies a double into it. The reference count for the |
2124 | SV is set to 1. |
cb1a09d0 |
2125 | |
2126 | SV* newSVnv _((NV i)); |
2127 | |
2128 | =item newSVpv |
2129 | |
07fa94a1 |
2130 | Creates a new SV and copies a string into it. The reference count for the |
2131 | SV is set to 1. If C<len> is zero then Perl will compute the length. |
cb1a09d0 |
2132 | |
2133 | SV* newSVpv _((char* s, STRLEN len)); |
2134 | |
2135 | =item newSVrv |
2136 | |
2137 | Creates a new SV for the RV, C<rv>, to point to. If C<rv> is not an RV then |
5fb8527f |
2138 | it will be upgraded to one. If C<classname> is non-null then the new SV will |
cb1a09d0 |
2139 | be blessed in the specified package. The new SV is returned and its |
5f05dabc |
2140 | reference count is 1. |
8ebc5c01 |
2141 | |
cb1a09d0 |
2142 | SV* newSVrv _((SV* rv, char* classname)); |
2143 | |
2144 | =item newSVsv |
2145 | |
5fb8527f |
2146 | Creates a new SV which is an exact duplicate of the original SV. |
cb1a09d0 |
2147 | |
2148 | SV* newSVsv _((SV* old)); |
2149 | |
2150 | =item newXS |
2151 | |
2152 | Used by C<xsubpp> to hook up XSUBs as Perl subs. |
2153 | |
2154 | =item newXSproto |
2155 | |
2156 | Used by C<xsubpp> to hook up XSUBs as Perl subs. Adds Perl prototypes to |
2157 | the subs. |
2158 | |
2159 | =item Nullav |
2160 | |
2161 | Null AV pointer. |
2162 | |
2163 | =item Nullch |
2164 | |
2165 | Null character pointer. |
2166 | |
2167 | =item Nullcv |
2168 | |
2169 | Null CV pointer. |
2170 | |
2171 | =item Nullhv |
2172 | |
2173 | Null HV pointer. |
2174 | |
2175 | =item Nullsv |
2176 | |
2177 | Null SV pointer. |
2178 | |
2179 | =item ORIGMARK |
2180 | |
2181 | The original stack mark for the XSUB. See C<dORIGMARK>. |
2182 | |
2183 | =item perl_alloc |
2184 | |
2185 | Allocates a new Perl interpreter. See L<perlembed>. |
2186 | |
2187 | =item perl_call_argv |
2188 | |
2189 | Performs a callback to the specified Perl sub. See L<perlcall>. |
2190 | |
2191 | I32 perl_call_argv _((char* subname, I32 flags, char** argv)); |
2192 | |
2193 | =item perl_call_method |
2194 | |
2195 | Performs a callback to the specified Perl method. The blessed object must |
2196 | be on the stack. See L<perlcall>. |
2197 | |
2198 | I32 perl_call_method _((char* methname, I32 flags)); |
2199 | |
2200 | =item perl_call_pv |
2201 | |
2202 | Performs a callback to the specified Perl sub. See L<perlcall>. |
2203 | |
2204 | I32 perl_call_pv _((char* subname, I32 flags)); |
2205 | |
2206 | =item perl_call_sv |
2207 | |
2208 | Performs a callback to the Perl sub whose name is in the SV. See |
2209 | L<perlcall>. |
2210 | |
2211 | I32 perl_call_sv _((SV* sv, I32 flags)); |
2212 | |
2213 | =item perl_construct |
2214 | |
2215 | Initializes a new Perl interpreter. See L<perlembed>. |
2216 | |
2217 | =item perl_destruct |
2218 | |
2219 | Shuts down a Perl interpreter. See L<perlembed>. |
2220 | |
2221 | =item perl_eval_sv |
2222 | |
2223 | Tells Perl to C<eval> the string in the SV. |
2224 | |
2225 | I32 perl_eval_sv _((SV* sv, I32 flags)); |
2226 | |
137443ea |
2227 | =item perl_eval_pv |
2228 | |
2229 | Tells Perl to C<eval> the given string and return an SV* result. |
2230 | |
2231 | SV* perl_eval_pv _((char* p, I32 croak_on_error)); |
2232 | |
cb1a09d0 |
2233 | =item perl_free |
2234 | |
2235 | Releases a Perl interpreter. See L<perlembed>. |
2236 | |
2237 | =item perl_get_av |
2238 | |
2239 | Returns the AV of the specified Perl array. If C<create> is set and the |
2240 | Perl variable does not exist then it will be created. If C<create> is not |
04343c6d |
2241 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2242 | |
2243 | AV* perl_get_av _((char* name, I32 create)); |
2244 | |
2245 | =item perl_get_cv |
2246 | |
2247 | Returns the CV of the specified Perl sub. If C<create> is set and the Perl |
2248 | variable does not exist then it will be created. If C<create> is not |
04343c6d |
2249 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2250 | |
2251 | CV* perl_get_cv _((char* name, I32 create)); |
2252 | |
2253 | =item perl_get_hv |
2254 | |
2255 | Returns the HV of the specified Perl hash. If C<create> is set and the Perl |
2256 | variable does not exist then it will be created. If C<create> is not |
04343c6d |
2257 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2258 | |
2259 | HV* perl_get_hv _((char* name, I32 create)); |
2260 | |
2261 | =item perl_get_sv |
2262 | |
2263 | Returns the SV of the specified Perl scalar. If C<create> is set and the |
2264 | Perl variable does not exist then it will be created. If C<create> is not |
04343c6d |
2265 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2266 | |
2267 | SV* perl_get_sv _((char* name, I32 create)); |
2268 | |
2269 | =item perl_parse |
2270 | |
2271 | Tells a Perl interpreter to parse a Perl script. See L<perlembed>. |
2272 | |
2273 | =item perl_require_pv |
2274 | |
2275 | Tells Perl to C<require> a module. |
2276 | |
2277 | void perl_require_pv _((char* pv)); |
2278 | |
2279 | =item perl_run |
2280 | |
2281 | Tells a Perl interpreter to run. See L<perlembed>. |
2282 | |
2283 | =item POPi |
2284 | |
2285 | Pops an integer off the stack. |
2286 | |
2287 | int POPi(); |
2288 | |
2289 | =item POPl |
2290 | |
2291 | Pops a long off the stack. |
2292 | |
2293 | long POPl(); |
2294 | |
2295 | =item POPp |
2296 | |
2297 | Pops a string off the stack. |
2298 | |
2299 | char * POPp(); |
2300 | |
2301 | =item POPn |
2302 | |
2303 | Pops a double off the stack. |
2304 | |
2305 | double POPn(); |
2306 | |
2307 | =item POPs |
2308 | |
2309 | Pops an SV off the stack. |
2310 | |
2311 | SV* POPs(); |
2312 | |
2313 | =item PUSHMARK |
2314 | |
2315 | Opening bracket for arguments on a callback. See C<PUTBACK> and L<perlcall>. |
2316 | |
2317 | PUSHMARK(p) |
2318 | |
2319 | =item PUSHi |
2320 | |
2321 | Push an integer onto the stack. The stack must have room for this element. |
2322 | See C<XPUSHi>. |
2323 | |
2324 | PUSHi(int d) |
2325 | |
2326 | =item PUSHn |
2327 | |
2328 | Push a double onto the stack. The stack must have room for this element. |
2329 | See C<XPUSHn>. |
2330 | |
2331 | PUSHn(double d) |
2332 | |
2333 | =item PUSHp |
2334 | |
2335 | Push a string onto the stack. The stack must have room for this element. |
2336 | The C<len> indicates the length of the string. See C<XPUSHp>. |
2337 | |
2338 | PUSHp(char *c, int len ) |
2339 | |
2340 | =item PUSHs |
2341 | |
2342 | Push an SV onto the stack. The stack must have room for this element. See |
2343 | C<XPUSHs>. |
2344 | |
2345 | PUSHs(sv) |
2346 | |
2347 | =item PUTBACK |
2348 | |
2349 | Closing bracket for XSUB arguments. This is usually handled by C<xsubpp>. |
2350 | See C<PUSHMARK> and L<perlcall> for other uses. |
2351 | |
2352 | PUTBACK; |
2353 | |
2354 | =item Renew |
2355 | |
2356 | The XSUB-writer's interface to the C C<realloc> function. |
2357 | |
2358 | void * Renew( void *ptr, int size, type ) |
2359 | |
2360 | =item Renewc |
2361 | |
2362 | The XSUB-writer's interface to the C C<realloc> function, with cast. |
2363 | |
2364 | void * Renewc( void *ptr, int size, type, cast ) |
2365 | |
2366 | =item RETVAL |
2367 | |
2368 | Variable which is setup by C<xsubpp> to hold the return value for an XSUB. |
5fb8527f |
2369 | This is always the proper type for the XSUB. |
2370 | See L<perlxs/"The RETVAL Variable">. |
cb1a09d0 |
2371 | |
2372 | =item safefree |
2373 | |
2374 | The XSUB-writer's interface to the C C<free> function. |
2375 | |
2376 | =item safemalloc |
2377 | |
2378 | The XSUB-writer's interface to the C C<malloc> function. |
2379 | |
2380 | =item saferealloc |
2381 | |
2382 | The XSUB-writer's interface to the C C<realloc> function. |
2383 | |
2384 | =item savepv |
2385 | |
2386 | Copy a string to a safe spot. This does not use an SV. |
2387 | |
2388 | char* savepv _((char* sv)); |
2389 | |
2390 | =item savepvn |
2391 | |
2392 | Copy a string to a safe spot. The C<len> indicates number of bytes to |
2393 | copy. This does not use an SV. |
2394 | |
2395 | char* savepvn _((char* sv, I32 len)); |
2396 | |
2397 | =item SAVETMPS |
2398 | |
2399 | Opening bracket for temporaries on a callback. See C<FREETMPS> and |
2400 | L<perlcall>. |
2401 | |
2402 | SAVETMPS; |
2403 | |
2404 | =item SP |
2405 | |
2406 | Stack pointer. This is usually handled by C<xsubpp>. See C<dSP> and |
2407 | C<SPAGAIN>. |
2408 | |
2409 | =item SPAGAIN |
2410 | |
54310121 |
2411 | Refetch the stack pointer. Used after a callback. See L<perlcall>. |
cb1a09d0 |
2412 | |
2413 | SPAGAIN; |
2414 | |
2415 | =item ST |
2416 | |
2417 | Used to access elements on the XSUB's stack. |
2418 | |
2419 | SV* ST(int x) |
2420 | |
2421 | =item strEQ |
2422 | |
2423 | Test two strings to see if they are equal. Returns true or false. |
2424 | |
2425 | int strEQ( char *s1, char *s2 ) |
2426 | |
2427 | =item strGE |
2428 | |
2429 | Test two strings to see if the first, C<s1>, is greater than or equal to the |
2430 | second, C<s2>. Returns true or false. |
2431 | |
2432 | int strGE( char *s1, char *s2 ) |
2433 | |
2434 | =item strGT |
2435 | |
2436 | Test two strings to see if the first, C<s1>, is greater than the second, |
2437 | C<s2>. Returns true or false. |
2438 | |
2439 | int strGT( char *s1, char *s2 ) |
2440 | |
2441 | =item strLE |
2442 | |
2443 | Test two strings to see if the first, C<s1>, is less than or equal to the |
2444 | second, C<s2>. Returns true or false. |
2445 | |
2446 | int strLE( char *s1, char *s2 ) |
2447 | |
2448 | =item strLT |
2449 | |
2450 | Test two strings to see if the first, C<s1>, is less than the second, |
2451 | C<s2>. Returns true or false. |
2452 | |
2453 | int strLT( char *s1, char *s2 ) |
2454 | |
2455 | =item strNE |
2456 | |
2457 | Test two strings to see if they are different. Returns true or false. |
2458 | |
2459 | int strNE( char *s1, char *s2 ) |
2460 | |
2461 | =item strnEQ |
2462 | |
2463 | Test two strings to see if they are equal. The C<len> parameter indicates |
2464 | the number of bytes to compare. Returns true or false. |
2465 | |
2466 | int strnEQ( char *s1, char *s2 ) |
2467 | |
2468 | =item strnNE |
2469 | |
2470 | Test two strings to see if they are different. The C<len> parameter |
2471 | indicates the number of bytes to compare. Returns true or false. |
2472 | |
2473 | int strnNE( char *s1, char *s2, int len ) |
2474 | |
2475 | =item sv_2mortal |
2476 | |
2477 | Marks an SV as mortal. The SV will be destroyed when the current context |
2478 | ends. |
2479 | |
2480 | SV* sv_2mortal _((SV* sv)); |
2481 | |
2482 | =item sv_bless |
2483 | |
2484 | Blesses an SV into a specified package. The SV must be an RV. The package |
07fa94a1 |
2485 | must be designated by its stash (see C<gv_stashpv()>). The reference count |
2486 | of the SV is unaffected. |
cb1a09d0 |
2487 | |
2488 | SV* sv_bless _((SV* sv, HV* stash)); |
2489 | |
2490 | =item sv_catpv |
2491 | |
2492 | Concatenates the string onto the end of the string which is in the SV. |
2493 | |
2494 | void sv_catpv _((SV* sv, char* ptr)); |
2495 | |
2496 | =item sv_catpvn |
2497 | |
2498 | Concatenates the string onto the end of the string which is in the SV. The |
2499 | C<len> indicates number of bytes to copy. |
2500 | |
2501 | void sv_catpvn _((SV* sv, char* ptr, STRLEN len)); |
2502 | |
46fc3d4c |
2503 | =item sv_catpvf |
2504 | |
2505 | Processes its arguments like C<sprintf> and appends the formatted output |
2506 | to an SV. |
2507 | |
2508 | void sv_catpvf _((SV* sv, const char* pat, ...)); |
2509 | |
cb1a09d0 |
2510 | =item sv_catsv |
2511 | |
5fb8527f |
2512 | Concatenates the string from SV C<ssv> onto the end of the string in SV |
cb1a09d0 |
2513 | C<dsv>. |
2514 | |
2515 | void sv_catsv _((SV* dsv, SV* ssv)); |
2516 | |
5fb8527f |
2517 | =item sv_cmp |
2518 | |
2519 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the |
2520 | string in C<sv1> is less than, equal to, or greater than the string in |
2521 | C<sv2>. |
2522 | |
2523 | I32 sv_cmp _((SV* sv1, SV* sv2)); |
2524 | |
cb1a09d0 |
2525 | =item SvCUR |
2526 | |
2527 | Returns the length of the string which is in the SV. See C<SvLEN>. |
2528 | |
2529 | int SvCUR (SV* sv) |
2530 | |
2531 | =item SvCUR_set |
2532 | |
2533 | Set the length of the string which is in the SV. See C<SvCUR>. |
2534 | |
2535 | SvCUR_set (SV* sv, int val ) |
2536 | |
5fb8527f |
2537 | =item sv_dec |
2538 | |
5f05dabc |
2539 | Auto-decrement of the value in the SV. |
5fb8527f |
2540 | |
2541 | void sv_dec _((SV* sv)); |
2542 | |
cb1a09d0 |
2543 | =item SvEND |
2544 | |
2545 | Returns a pointer to the last character in the string which is in the SV. |
2546 | See C<SvCUR>. Access the character as |
2547 | |
2548 | *SvEND(sv) |
2549 | |
5fb8527f |
2550 | =item sv_eq |
2551 | |
2552 | Returns a boolean indicating whether the strings in the two SVs are |
2553 | identical. |
2554 | |
2555 | I32 sv_eq _((SV* sv1, SV* sv2)); |
2556 | |
cb1a09d0 |
2557 | =item SvGROW |
2558 | |
5fb8527f |
2559 | Expands the character buffer in the SV. Calls C<sv_grow> to perform the |
2560 | expansion if necessary. Returns a pointer to the character buffer. |
cb1a09d0 |
2561 | |
2562 | char * SvGROW( SV* sv, int len ) |
2563 | |
5fb8527f |
2564 | =item sv_grow |
2565 | |
2566 | Expands the character buffer in the SV. This will use C<sv_unref> and will |
2567 | upgrade the SV to C<SVt_PV>. Returns a pointer to the character buffer. |
2568 | Use C<SvGROW>. |
2569 | |
2570 | =item sv_inc |
2571 | |
07fa94a1 |
2572 | Auto-increment of the value in the SV. |
5fb8527f |
2573 | |
2574 | void sv_inc _((SV* sv)); |
2575 | |
cb1a09d0 |
2576 | =item SvIOK |
2577 | |
2578 | Returns a boolean indicating whether the SV contains an integer. |
2579 | |
2580 | int SvIOK (SV* SV) |
2581 | |
2582 | =item SvIOK_off |
2583 | |
2584 | Unsets the IV status of an SV. |
2585 | |
2586 | SvIOK_off (SV* sv) |
2587 | |
2588 | =item SvIOK_on |
2589 | |
2590 | Tells an SV that it is an integer. |
2591 | |
2592 | SvIOK_on (SV* sv) |
2593 | |
5fb8527f |
2594 | =item SvIOK_only |
2595 | |
2596 | Tells an SV that it is an integer and disables all other OK bits. |
2597 | |
2598 | SvIOK_on (SV* sv) |
2599 | |
cb1a09d0 |
2600 | =item SvIOKp |
2601 | |
2602 | Returns a boolean indicating whether the SV contains an integer. Checks the |
2603 | B<private> setting. Use C<SvIOK>. |
2604 | |
2605 | int SvIOKp (SV* SV) |
2606 | |
2607 | =item sv_isa |
2608 | |
2609 | Returns a boolean indicating whether the SV is blessed into the specified |
2610 | class. This does not know how to check for subtype, so it doesn't work in |
2611 | an inheritance relationship. |
2612 | |
2613 | int sv_isa _((SV* sv, char* name)); |
2614 | |
2615 | =item SvIV |
2616 | |
2617 | Returns the integer which is in the SV. |
2618 | |
2619 | int SvIV (SV* sv) |
2620 | |
2621 | =item sv_isobject |
2622 | |
2623 | Returns a boolean indicating whether the SV is an RV pointing to a blessed |
2624 | object. If the SV is not an RV, or if the object is not blessed, then this |
2625 | will return false. |
2626 | |
2627 | int sv_isobject _((SV* sv)); |
2628 | |
2629 | =item SvIVX |
2630 | |
2631 | Returns the integer which is stored in the SV. |
2632 | |
2633 | int SvIVX (SV* sv); |
2634 | |
2635 | =item SvLEN |
2636 | |
2637 | Returns the size of the string buffer in the SV. See C<SvCUR>. |
2638 | |
2639 | int SvLEN (SV* sv) |
2640 | |
5fb8527f |
2641 | =item sv_len |
2642 | |
2643 | Returns the length of the string in the SV. Use C<SvCUR>. |
2644 | |
2645 | STRLEN sv_len _((SV* sv)); |
2646 | |
cb1a09d0 |
2647 | =item sv_magic |
2648 | |
2649 | Adds magic to an SV. |
2650 | |
2651 | void sv_magic _((SV* sv, SV* obj, int how, char* name, I32 namlen)); |
2652 | |
2653 | =item sv_mortalcopy |
2654 | |
2655 | Creates a new SV which is a copy of the original SV. The new SV is marked |
5f05dabc |
2656 | as mortal. |
cb1a09d0 |
2657 | |
2658 | SV* sv_mortalcopy _((SV* oldsv)); |
2659 | |
2660 | =item SvOK |
2661 | |
2662 | Returns a boolean indicating whether the value is an SV. |
2663 | |
2664 | int SvOK (SV* sv) |
2665 | |
2666 | =item sv_newmortal |
2667 | |
5f05dabc |
2668 | Creates a new SV which is mortal. The reference count of the SV is set to 1. |
cb1a09d0 |
2669 | |
2670 | SV* sv_newmortal _((void)); |
2671 | |
2672 | =item sv_no |
2673 | |
2674 | This is the C<false> SV. See C<sv_yes>. Always refer to this as C<&sv_no>. |
2675 | |
2676 | =item SvNIOK |
2677 | |
2678 | Returns a boolean indicating whether the SV contains a number, integer or |
2679 | double. |
2680 | |
2681 | int SvNIOK (SV* SV) |
2682 | |
2683 | =item SvNIOK_off |
2684 | |
2685 | Unsets the NV/IV status of an SV. |
2686 | |
2687 | SvNIOK_off (SV* sv) |
2688 | |
2689 | =item SvNIOKp |
2690 | |
2691 | Returns a boolean indicating whether the SV contains a number, integer or |
2692 | double. Checks the B<private> setting. Use C<SvNIOK>. |
2693 | |
2694 | int SvNIOKp (SV* SV) |
2695 | |
2696 | =item SvNOK |
2697 | |
2698 | Returns a boolean indicating whether the SV contains a double. |
2699 | |
2700 | int SvNOK (SV* SV) |
2701 | |
2702 | =item SvNOK_off |
2703 | |
2704 | Unsets the NV status of an SV. |
2705 | |
2706 | SvNOK_off (SV* sv) |
2707 | |
2708 | =item SvNOK_on |
2709 | |
2710 | Tells an SV that it is a double. |
2711 | |
2712 | SvNOK_on (SV* sv) |
2713 | |
5fb8527f |
2714 | =item SvNOK_only |
2715 | |
2716 | Tells an SV that it is a double and disables all other OK bits. |
2717 | |
2718 | SvNOK_on (SV* sv) |
2719 | |
cb1a09d0 |
2720 | =item SvNOKp |
2721 | |
2722 | Returns a boolean indicating whether the SV contains a double. Checks the |
2723 | B<private> setting. Use C<SvNOK>. |
2724 | |
2725 | int SvNOKp (SV* SV) |
2726 | |
2727 | =item SvNV |
2728 | |
2729 | Returns the double which is stored in the SV. |
2730 | |
2731 | double SvNV (SV* sv); |
2732 | |
2733 | =item SvNVX |
2734 | |
2735 | Returns the double which is stored in the SV. |
2736 | |
2737 | double SvNVX (SV* sv); |
2738 | |
2739 | =item SvPOK |
2740 | |
2741 | Returns a boolean indicating whether the SV contains a character string. |
2742 | |
2743 | int SvPOK (SV* SV) |
2744 | |
2745 | =item SvPOK_off |
2746 | |
2747 | Unsets the PV status of an SV. |
2748 | |
2749 | SvPOK_off (SV* sv) |
2750 | |
2751 | =item SvPOK_on |
2752 | |
2753 | Tells an SV that it is a string. |
2754 | |
2755 | SvPOK_on (SV* sv) |
2756 | |
5fb8527f |
2757 | =item SvPOK_only |
2758 | |
2759 | Tells an SV that it is a string and disables all other OK bits. |
2760 | |
2761 | SvPOK_on (SV* sv) |
2762 | |
cb1a09d0 |
2763 | =item SvPOKp |
2764 | |
2765 | Returns a boolean indicating whether the SV contains a character string. |
2766 | Checks the B<private> setting. Use C<SvPOK>. |
2767 | |
2768 | int SvPOKp (SV* SV) |
2769 | |
2770 | =item SvPV |
2771 | |
2772 | Returns a pointer to the string in the SV, or a stringified form of the SV |
2773 | if the SV does not contain a string. If C<len> is C<na> then Perl will |
2774 | handle the length on its own. |
2775 | |
2776 | char * SvPV (SV* sv, int len ) |
2777 | |
2778 | =item SvPVX |
2779 | |
2780 | Returns a pointer to the string in the SV. The SV must contain a string. |
2781 | |
2782 | char * SvPVX (SV* sv) |
2783 | |
2784 | =item SvREFCNT |
2785 | |
5f05dabc |
2786 | Returns the value of the object's reference count. |
cb1a09d0 |
2787 | |
2788 | int SvREFCNT (SV* sv); |
2789 | |
2790 | =item SvREFCNT_dec |
2791 | |
5f05dabc |
2792 | Decrements the reference count of the given SV. |
cb1a09d0 |
2793 | |
2794 | void SvREFCNT_dec (SV* sv) |
2795 | |
2796 | =item SvREFCNT_inc |
2797 | |
5f05dabc |
2798 | Increments the reference count of the given SV. |
cb1a09d0 |
2799 | |
2800 | void SvREFCNT_inc (SV* sv) |
2801 | |
2802 | =item SvROK |
2803 | |
2804 | Tests if the SV is an RV. |
2805 | |
2806 | int SvROK (SV* sv) |
2807 | |
2808 | =item SvROK_off |
2809 | |
2810 | Unsets the RV status of an SV. |
2811 | |
2812 | SvROK_off (SV* sv) |
2813 | |
2814 | =item SvROK_on |
2815 | |
2816 | Tells an SV that it is an RV. |
2817 | |
2818 | SvROK_on (SV* sv) |
2819 | |
2820 | =item SvRV |
2821 | |
2822 | Dereferences an RV to return the SV. |
2823 | |
2824 | SV* SvRV (SV* sv); |
2825 | |
2826 | =item sv_setiv |
2827 | |
2828 | Copies an integer into the given SV. |
2829 | |
2830 | void sv_setiv _((SV* sv, IV num)); |
2831 | |
2832 | =item sv_setnv |
2833 | |
2834 | Copies a double into the given SV. |
2835 | |
2836 | void sv_setnv _((SV* sv, double num)); |
2837 | |
2838 | =item sv_setpv |
2839 | |
2840 | Copies a string into an SV. The string must be null-terminated. |
2841 | |
2842 | void sv_setpv _((SV* sv, char* ptr)); |
2843 | |
2844 | =item sv_setpvn |
2845 | |
2846 | Copies a string into an SV. The C<len> parameter indicates the number of |
2847 | bytes to be copied. |
2848 | |
2849 | void sv_setpvn _((SV* sv, char* ptr, STRLEN len)); |
2850 | |
46fc3d4c |
2851 | =item sv_setpvf |
2852 | |
2853 | Processes its arguments like C<sprintf> and sets an SV to the formatted |
2854 | output. |
2855 | |
2856 | void sv_setpvf _((SV* sv, const char* pat, ...)); |
2857 | |
cb1a09d0 |
2858 | =item sv_setref_iv |
2859 | |
5fb8527f |
2860 | Copies an integer into a new SV, optionally blessing the SV. The C<rv> |
2861 | argument will be upgraded to an RV. That RV will be modified to point to |
2862 | the new SV. The C<classname> argument indicates the package for the |
2863 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
2864 | will be returned and will have a reference count of 1. |
cb1a09d0 |
2865 | |
2866 | SV* sv_setref_iv _((SV *rv, char *classname, IV iv)); |
2867 | |
2868 | =item sv_setref_nv |
2869 | |
5fb8527f |
2870 | Copies a double into a new SV, optionally blessing the SV. The C<rv> |
2871 | argument will be upgraded to an RV. That RV will be modified to point to |
2872 | the new SV. The C<classname> argument indicates the package for the |
2873 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
2874 | will be returned and will have a reference count of 1. |
cb1a09d0 |
2875 | |
2876 | SV* sv_setref_nv _((SV *rv, char *classname, double nv)); |
2877 | |
2878 | =item sv_setref_pv |
2879 | |
5fb8527f |
2880 | Copies a pointer into a new SV, optionally blessing the SV. The C<rv> |
2881 | argument will be upgraded to an RV. That RV will be modified to point to |
2882 | the new SV. If the C<pv> argument is NULL then C<sv_undef> will be placed |
2883 | into the SV. The C<classname> argument indicates the package for the |
2884 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
2885 | will be returned and will have a reference count of 1. |
cb1a09d0 |
2886 | |
2887 | SV* sv_setref_pv _((SV *rv, char *classname, void* pv)); |
2888 | |
2889 | Do not use with integral Perl types such as HV, AV, SV, CV, because those |
2890 | objects will become corrupted by the pointer copy process. |
2891 | |
2892 | Note that C<sv_setref_pvn> copies the string while this copies the pointer. |
2893 | |
2894 | =item sv_setref_pvn |
2895 | |
5fb8527f |
2896 | Copies a string into a new SV, optionally blessing the SV. The length of the |
2897 | string must be specified with C<n>. The C<rv> argument will be upgraded to |
2898 | an RV. That RV will be modified to point to the new SV. The C<classname> |
cb1a09d0 |
2899 | argument indicates the package for the blessing. Set C<classname> to |
2900 | C<Nullch> to avoid the blessing. The new SV will be returned and will have |
5f05dabc |
2901 | a reference count of 1. |
cb1a09d0 |
2902 | |
2903 | SV* sv_setref_pvn _((SV *rv, char *classname, char* pv, I32 n)); |
2904 | |
2905 | Note that C<sv_setref_pv> copies the pointer while this copies the string. |
2906 | |
2907 | =item sv_setsv |
2908 | |
2909 | Copies the contents of the source SV C<ssv> into the destination SV C<dsv>. |
5f05dabc |
2910 | The source SV may be destroyed if it is mortal. |
cb1a09d0 |
2911 | |
2912 | void sv_setsv _((SV* dsv, SV* ssv)); |
2913 | |
2914 | =item SvSTASH |
2915 | |
2916 | Returns the stash of the SV. |
2917 | |
2918 | HV * SvSTASH (SV* sv) |
2919 | |
2920 | =item SVt_IV |
2921 | |
2922 | Integer type flag for scalars. See C<svtype>. |
2923 | |
2924 | =item SVt_PV |
2925 | |
2926 | Pointer type flag for scalars. See C<svtype>. |
2927 | |
2928 | =item SVt_PVAV |
2929 | |
2930 | Type flag for arrays. See C<svtype>. |
2931 | |
2932 | =item SVt_PVCV |
2933 | |
2934 | Type flag for code refs. See C<svtype>. |
2935 | |
2936 | =item SVt_PVHV |
2937 | |
2938 | Type flag for hashes. See C<svtype>. |
2939 | |
2940 | =item SVt_PVMG |
2941 | |
2942 | Type flag for blessed scalars. See C<svtype>. |
2943 | |
2944 | =item SVt_NV |
2945 | |
2946 | Double type flag for scalars. See C<svtype>. |
2947 | |
2948 | =item SvTRUE |
2949 | |
2950 | Returns a boolean indicating whether Perl would evaluate the SV as true or |
2951 | false, defined or undefined. |
2952 | |
2953 | int SvTRUE (SV* sv) |
2954 | |
2955 | =item SvTYPE |
2956 | |
2957 | Returns the type of the SV. See C<svtype>. |
2958 | |
2959 | svtype SvTYPE (SV* sv) |
2960 | |
2961 | =item svtype |
2962 | |
2963 | An enum of flags for Perl types. These are found in the file B<sv.h> in the |
2964 | C<svtype> enum. Test these flags with the C<SvTYPE> macro. |
2965 | |
2966 | =item SvUPGRADE |
2967 | |
5fb8527f |
2968 | Used to upgrade an SV to a more complex form. Uses C<sv_upgrade> to perform |
2969 | the upgrade if necessary. See C<svtype>. |
2970 | |
2971 | bool SvUPGRADE _((SV* sv, svtype mt)); |
2972 | |
2973 | =item sv_upgrade |
2974 | |
2975 | Upgrade an SV to a more complex form. Use C<SvUPGRADE>. See C<svtype>. |
cb1a09d0 |
2976 | |
2977 | =item sv_undef |
2978 | |
2979 | This is the C<undef> SV. Always refer to this as C<&sv_undef>. |
2980 | |
5fb8527f |
2981 | =item sv_unref |
2982 | |
07fa94a1 |
2983 | Unsets the RV status of the SV, and decrements the reference count of |
2984 | whatever was being referenced by the RV. This can almost be thought of |
2985 | as a reversal of C<newSVrv>. See C<SvROK_off>. |
5fb8527f |
2986 | |
2987 | void sv_unref _((SV* sv)); |
2988 | |
cb1a09d0 |
2989 | =item sv_usepvn |
2990 | |
2991 | Tells an SV to use C<ptr> to find its string value. Normally the string is |
5fb8527f |
2992 | stored inside the SV but sv_usepvn allows the SV to use an outside string. |
2993 | The C<ptr> should point to memory that was allocated by C<malloc>. The |
cb1a09d0 |
2994 | string length, C<len>, must be supplied. This function will realloc the |
2995 | memory pointed to by C<ptr>, so that pointer should not be freed or used by |
2996 | the programmer after giving it to sv_usepvn. |
2997 | |
2998 | void sv_usepvn _((SV* sv, char* ptr, STRLEN len)); |
2999 | |
3000 | =item sv_yes |
3001 | |
3002 | This is the C<true> SV. See C<sv_no>. Always refer to this as C<&sv_yes>. |
3003 | |
3004 | =item THIS |
3005 | |
3006 | Variable which is setup by C<xsubpp> to designate the object in a C++ XSUB. |
3007 | This is always the proper type for the C++ object. See C<CLASS> and |
5fb8527f |
3008 | L<perlxs/"Using XS With C++">. |
cb1a09d0 |
3009 | |
3010 | =item toLOWER |
3011 | |
3012 | Converts the specified character to lowercase. |
3013 | |
3014 | int toLOWER (char c) |
3015 | |
3016 | =item toUPPER |
3017 | |
3018 | Converts the specified character to uppercase. |
3019 | |
3020 | int toUPPER (char c) |
3021 | |
3022 | =item warn |
3023 | |
3024 | This is the XSUB-writer's interface to Perl's C<warn> function. Use this |
3025 | function the same way you use the C C<printf> function. See C<croak()>. |
3026 | |
3027 | =item XPUSHi |
3028 | |
3029 | Push an integer onto the stack, extending the stack if necessary. See |
3030 | C<PUSHi>. |
3031 | |
3032 | XPUSHi(int d) |
3033 | |
3034 | =item XPUSHn |
3035 | |
3036 | Push a double onto the stack, extending the stack if necessary. See |
3037 | C<PUSHn>. |
3038 | |
3039 | XPUSHn(double d) |
3040 | |
3041 | =item XPUSHp |
3042 | |
3043 | Push a string onto the stack, extending the stack if necessary. The C<len> |
3044 | indicates the length of the string. See C<PUSHp>. |
3045 | |
3046 | XPUSHp(char *c, int len) |
3047 | |
3048 | =item XPUSHs |
3049 | |
3050 | Push an SV onto the stack, extending the stack if necessary. See C<PUSHs>. |
3051 | |
3052 | XPUSHs(sv) |
3053 | |
5fb8527f |
3054 | =item XS |
3055 | |
3056 | Macro to declare an XSUB and its C parameter list. This is handled by |
3057 | C<xsubpp>. |
3058 | |
cb1a09d0 |
3059 | =item XSRETURN |
3060 | |
3061 | Return from XSUB, indicating number of items on the stack. This is usually |
3062 | handled by C<xsubpp>. |
3063 | |
5fb8527f |
3064 | XSRETURN(int x); |
cb1a09d0 |
3065 | |
3066 | =item XSRETURN_EMPTY |
3067 | |
5fb8527f |
3068 | Return an empty list from an XSUB immediately. |
cb1a09d0 |
3069 | |
3070 | XSRETURN_EMPTY; |
3071 | |
5fb8527f |
3072 | =item XSRETURN_IV |
3073 | |
3074 | Return an integer from an XSUB immediately. Uses C<XST_mIV>. |
3075 | |
3076 | XSRETURN_IV(IV v); |
3077 | |
cb1a09d0 |
3078 | =item XSRETURN_NO |
3079 | |
5fb8527f |
3080 | Return C<&sv_no> from an XSUB immediately. Uses C<XST_mNO>. |
cb1a09d0 |
3081 | |
3082 | XSRETURN_NO; |
3083 | |
5fb8527f |
3084 | =item XSRETURN_NV |
3085 | |
3086 | Return an double from an XSUB immediately. Uses C<XST_mNV>. |
3087 | |
3088 | XSRETURN_NV(NV v); |
3089 | |
3090 | =item XSRETURN_PV |
3091 | |
3092 | Return a copy of a string from an XSUB immediately. Uses C<XST_mPV>. |
3093 | |
3094 | XSRETURN_PV(char *v); |
3095 | |
cb1a09d0 |
3096 | =item XSRETURN_UNDEF |
3097 | |
5fb8527f |
3098 | Return C<&sv_undef> from an XSUB immediately. Uses C<XST_mUNDEF>. |
cb1a09d0 |
3099 | |
3100 | XSRETURN_UNDEF; |
3101 | |
3102 | =item XSRETURN_YES |
3103 | |
5fb8527f |
3104 | Return C<&sv_yes> from an XSUB immediately. Uses C<XST_mYES>. |
cb1a09d0 |
3105 | |
3106 | XSRETURN_YES; |
3107 | |
5fb8527f |
3108 | =item XST_mIV |
3109 | |
3110 | Place an integer into the specified position C<i> on the stack. The value is |
3111 | stored in a new mortal SV. |
3112 | |
3113 | XST_mIV( int i, IV v ); |
3114 | |
3115 | =item XST_mNV |
3116 | |
3117 | Place a double into the specified position C<i> on the stack. The value is |
3118 | stored in a new mortal SV. |
3119 | |
3120 | XST_mNV( int i, NV v ); |
3121 | |
3122 | =item XST_mNO |
3123 | |
3124 | Place C<&sv_no> into the specified position C<i> on the stack. |
3125 | |
3126 | XST_mNO( int i ); |
3127 | |
3128 | =item XST_mPV |
3129 | |
3130 | Place a copy of a string into the specified position C<i> on the stack. The |
3131 | value is stored in a new mortal SV. |
3132 | |
3133 | XST_mPV( int i, char *v ); |
3134 | |
3135 | =item XST_mUNDEF |
3136 | |
3137 | Place C<&sv_undef> into the specified position C<i> on the stack. |
3138 | |
3139 | XST_mUNDEF( int i ); |
3140 | |
3141 | =item XST_mYES |
3142 | |
3143 | Place C<&sv_yes> into the specified position C<i> on the stack. |
3144 | |
3145 | XST_mYES( int i ); |
3146 | |
3147 | =item XS_VERSION |
3148 | |
3149 | The version identifier for an XS module. This is usually handled |
3150 | automatically by C<ExtUtils::MakeMaker>. See C<XS_VERSION_BOOTCHECK>. |
3151 | |
3152 | =item XS_VERSION_BOOTCHECK |
3153 | |
3154 | Macro to verify that a PM module's $VERSION variable matches the XS module's |
3155 | C<XS_VERSION> variable. This is usually handled automatically by |
3156 | C<xsubpp>. See L<perlxs/"The VERSIONCHECK: Keyword">. |
3157 | |
cb1a09d0 |
3158 | =item Zero |
3159 | |
3160 | The XSUB-writer's interface to the C C<memzero> function. The C<d> is the |
3161 | destination, C<n> is the number of items, and C<t> is the type. |
3162 | |
3163 | (void) Zero( d, n, t ); |
3164 | |
3165 | =back |
3166 | |
5f05dabc |
3167 | =head1 EDITOR |
cb1a09d0 |
3168 | |
9607fc9c |
3169 | Jeff Okamoto <F<okamoto@corp.hp.com>> |
cb1a09d0 |
3170 | |
3171 | With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, |
3172 | Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil |
bdbeb323 |
3173 | Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, and |
3174 | Stephen McCamant. |
cb1a09d0 |
3175 | |
9607fc9c |
3176 | API Listing by Dean Roehrich <F<roehrich@cray.com>>. |
cb1a09d0 |
3177 | |
3178 | =head1 DATE |
3179 | |
04343c6d |
3180 | Version 31.8: 1997/5/17 |