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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 six 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* newSVpvn(char*, int); |
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43 | SV* newSVpvf(const char*, ...); |
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44 | SV* newSVsv(SV*); |
45 | |
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46 | To change the value of an *already-existing* SV, there are seven routines: |
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47 | |
48 | void sv_setiv(SV*, IV); |
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49 | void sv_setuv(SV*, UV); |
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50 | void sv_setnv(SV*, double); |
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51 | void sv_setpv(SV*, char*); |
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52 | void sv_setpvn(SV*, char*, int) |
53 | void sv_setpvf(SV*, const char*, ...); |
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54 | void sv_setpvfn(SV*, const char*, STRLEN, va_list *, SV **, I32, bool); |
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55 | void sv_setsv(SV*, SV*); |
56 | |
57 | Notice that you can choose to specify the length of the string to be |
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58 | assigned by using C<sv_setpvn>, C<newSVpvn>, or C<newSVpv>, or you may |
59 | allow Perl to calculate the length by using C<sv_setpv> or by specifying |
60 | 0 as the second argument to C<newSVpv>. Be warned, though, that Perl will |
61 | determine the string's length by using C<strlen>, which depends on the |
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62 | string terminating with a NUL character. |
63 | |
64 | The arguments of C<sv_setpvf> are processed like C<sprintf>, and the |
65 | formatted output becomes the value. |
66 | |
67 | C<sv_setpvfn> is an analogue of C<vsprintf>, but it allows you to specify |
68 | either a pointer to a variable argument list or the address and length of |
69 | an array of SVs. The last argument points to a boolean; on return, if that |
70 | boolean is true, then locale-specific information has been used to format |
71 | the string, and the string's contents are therefore untrustworty (see |
72 | L<perlsec>). This pointer may be NULL if that information is not |
73 | important. Note that this function requires you to specify the length of |
74 | the format. |
75 | |
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76 | The C<sv_set*()> functions are not generic enough to operate on values |
77 | that have "magic". See L<Magic Virtual Tables> later in this document. |
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78 | |
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79 | All SVs that contain strings should be terminated with a NUL character. |
80 | If it is not NUL-terminated there is a risk of |
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81 | core dumps and corruptions from code which passes the string to C |
82 | functions or system calls which expect a NUL-terminated string. |
83 | Perl's own functions typically add a trailing NUL for this reason. |
84 | Nevertheless, you should be very careful when you pass a string stored |
85 | in an SV to a C function or system call. |
86 | |
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87 | To access the actual value that an SV points to, you can use the macros: |
88 | |
89 | SvIV(SV*) |
90 | SvNV(SV*) |
91 | SvPV(SV*, STRLEN len) |
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92 | SvPV_nolen(SV*) |
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93 | |
94 | which will automatically coerce the actual scalar type into an IV, double, |
95 | or string. |
96 | |
97 | In the C<SvPV> macro, the length of the string returned is placed into the |
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98 | variable C<len> (this is a macro, so you do I<not> use C<&len>). If you do |
99 | not care what the length of the data is, use the C<SvPV_nolen> macro. |
100 | Historically the C<SvPV> macro with the global variable C<PL_na> has been |
101 | used in this case. But that can be quite inefficient because C<PL_na> must |
102 | be accessed in thread-local storage in threaded Perl. In any case, remember |
103 | that Perl allows arbitrary strings of data that may both contain NULs and |
104 | might not be terminated by a NUL. |
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105 | |
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106 | Also remember that C doesn't allow you to safely say C<foo(SvPV(s, len), |
107 | len);>. It might work with your compiler, but it won't work for everyone. |
108 | Break this sort of statement up into separate assignments: |
109 | |
110 | STRLEN len; |
111 | char * ptr; |
112 | ptr = SvPV(len); |
113 | foo(ptr, len); |
114 | |
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115 | If you want to know if the scalar value is TRUE, you can use: |
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116 | |
117 | SvTRUE(SV*) |
118 | |
119 | Although Perl will automatically grow strings for you, if you need to force |
120 | Perl to allocate more memory for your SV, you can use the macro |
121 | |
122 | SvGROW(SV*, STRLEN newlen) |
123 | |
124 | which will determine if more memory needs to be allocated. If so, it will |
125 | call the function C<sv_grow>. Note that C<SvGROW> can only increase, not |
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126 | decrease, the allocated memory of an SV and that it does not automatically |
127 | add a byte for the a trailing NUL (perl's own string functions typically do |
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128 | C<SvGROW(sv, len + 1)>). |
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129 | |
130 | If you have an SV and want to know what kind of data Perl thinks is stored |
131 | in it, you can use the following macros to check the type of SV you have. |
132 | |
133 | SvIOK(SV*) |
134 | SvNOK(SV*) |
135 | SvPOK(SV*) |
136 | |
137 | You can get and set the current length of the string stored in an SV with |
138 | the following macros: |
139 | |
140 | SvCUR(SV*) |
141 | SvCUR_set(SV*, I32 val) |
142 | |
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143 | You can also get a pointer to the end of the string stored in the SV |
144 | with the macro: |
145 | |
146 | SvEND(SV*) |
147 | |
148 | But note that these last three macros are valid only if C<SvPOK()> is true. |
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149 | |
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150 | If you want to append something to the end of string stored in an C<SV*>, |
151 | you can use the following functions: |
152 | |
153 | void sv_catpv(SV*, char*); |
154 | void sv_catpvn(SV*, char*, int); |
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155 | void sv_catpvf(SV*, const char*, ...); |
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156 | void sv_catpvfn(SV*, const char*, STRLEN, va_list *, SV **, I32, bool); |
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157 | void sv_catsv(SV*, SV*); |
158 | |
159 | The first function calculates the length of the string to be appended by |
160 | using C<strlen>. In the second, you specify the length of the string |
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161 | yourself. The third function processes its arguments like C<sprintf> and |
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162 | appends the formatted output. The fourth function works like C<vsprintf>. |
163 | You can specify the address and length of an array of SVs instead of the |
164 | va_list argument. The fifth function extends the string stored in the first |
165 | SV with the string stored in the second SV. It also forces the second SV |
166 | to be interpreted as a string. |
167 | |
168 | The C<sv_cat*()> functions are not generic enough to operate on values that |
169 | have "magic". See L<Magic Virtual Tables> later in this document. |
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170 | |
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171 | If you know the name of a scalar variable, you can get a pointer to its SV |
172 | by using the following: |
173 | |
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174 | SV* perl_get_sv("package::varname", FALSE); |
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175 | |
176 | This returns NULL if the variable does not exist. |
177 | |
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178 | If you want to know if this variable (or any other SV) is actually C<defined>, |
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179 | you can call: |
180 | |
181 | SvOK(SV*) |
182 | |
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183 | The scalar C<undef> value is stored in an SV instance called C<PL_sv_undef>. Its |
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184 | address can be used whenever an C<SV*> is needed. |
185 | |
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186 | There are also the two values C<PL_sv_yes> and C<PL_sv_no>, which contain Boolean |
187 | TRUE and FALSE values, respectively. Like C<PL_sv_undef>, their addresses can |
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188 | be used whenever an C<SV*> is needed. |
189 | |
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190 | Do not be fooled into thinking that C<(SV *) 0> is the same as C<&PL_sv_undef>. |
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191 | Take this code: |
192 | |
193 | SV* sv = (SV*) 0; |
194 | if (I-am-to-return-a-real-value) { |
195 | sv = sv_2mortal(newSViv(42)); |
196 | } |
197 | sv_setsv(ST(0), sv); |
198 | |
199 | This code tries to return a new SV (which contains the value 42) if it should |
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200 | return a real value, or undef otherwise. Instead it has returned a NULL |
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201 | pointer which, somewhere down the line, will cause a segmentation violation, |
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202 | bus error, or just weird results. Change the zero to C<&PL_sv_undef> in the first |
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203 | line and all will be well. |
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204 | |
205 | To free an SV that you've created, call C<SvREFCNT_dec(SV*)>. Normally this |
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206 | call is not necessary (see L<Reference Counts and Mortality>). |
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207 | |
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208 | =head2 What's Really Stored in an SV? |
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209 | |
210 | Recall that the usual method of determining the type of scalar you have is |
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211 | to use C<Sv*OK> macros. Because a scalar can be both a number and a string, |
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212 | usually these macros will always return TRUE and calling the C<Sv*V> |
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213 | macros will do the appropriate conversion of string to integer/double or |
214 | integer/double to string. |
215 | |
216 | If you I<really> need to know if you have an integer, double, or string |
217 | pointer in an SV, you can use the following three macros instead: |
218 | |
219 | SvIOKp(SV*) |
220 | SvNOKp(SV*) |
221 | SvPOKp(SV*) |
222 | |
223 | These will tell you if you truly have an integer, double, or string pointer |
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224 | stored in your SV. The "p" stands for private. |
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225 | |
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226 | In general, though, it's best to use the C<Sv*V> macros. |
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227 | |
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228 | =head2 Working with AVs |
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229 | |
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230 | There are two ways to create and load an AV. The first method creates an |
231 | empty AV: |
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232 | |
233 | AV* newAV(); |
234 | |
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235 | The second method both creates the AV and initially populates it with SVs: |
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236 | |
237 | AV* av_make(I32 num, SV **ptr); |
238 | |
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239 | The second argument points to an array containing C<num> C<SV*>'s. Once the |
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240 | AV has been created, the SVs can be destroyed, if so desired. |
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241 | |
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242 | Once the AV has been created, the following operations are possible on AVs: |
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243 | |
244 | void av_push(AV*, SV*); |
245 | SV* av_pop(AV*); |
246 | SV* av_shift(AV*); |
247 | void av_unshift(AV*, I32 num); |
248 | |
249 | These should be familiar operations, with the exception of C<av_unshift>. |
250 | This routine adds C<num> elements at the front of the array with the C<undef> |
251 | value. You must then use C<av_store> (described below) to assign values |
252 | to these new elements. |
253 | |
254 | Here are some other functions: |
255 | |
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256 | I32 av_len(AV*); |
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257 | SV** av_fetch(AV*, I32 key, I32 lval); |
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258 | SV** av_store(AV*, I32 key, SV* val); |
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259 | |
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260 | The C<av_len> function returns the highest index value in array (just |
261 | like $#array in Perl). If the array is empty, -1 is returned. The |
262 | C<av_fetch> function returns the value at index C<key>, but if C<lval> |
263 | is non-zero, then C<av_fetch> will store an undef value at that index. |
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264 | The C<av_store> function stores the value C<val> at index C<key>, and does |
265 | not increment the reference count of C<val>. Thus the caller is responsible |
266 | for taking care of that, and if C<av_store> returns NULL, the caller will |
267 | have to decrement the reference count to avoid a memory leak. Note that |
268 | C<av_fetch> and C<av_store> both return C<SV**>'s, not C<SV*>'s as their |
269 | return value. |
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270 | |
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271 | void av_clear(AV*); |
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272 | void av_undef(AV*); |
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273 | void av_extend(AV*, I32 key); |
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274 | |
275 | The C<av_clear> function deletes all the elements in the AV* array, but |
276 | does not actually delete the array itself. The C<av_undef> function will |
277 | delete all the elements in the array plus the array itself. The |
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278 | C<av_extend> function extends the array so that it contains at least C<key+1> |
279 | elements. If C<key+1> is less than the currently allocated length of the array, |
280 | then nothing is done. |
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281 | |
282 | If you know the name of an array variable, you can get a pointer to its AV |
283 | by using the following: |
284 | |
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285 | AV* perl_get_av("package::varname", FALSE); |
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286 | |
287 | This returns NULL if the variable does not exist. |
288 | |
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289 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
290 | information on how to use the array access functions on tied arrays. |
291 | |
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292 | =head2 Working with HVs |
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293 | |
294 | To create an HV, you use the following routine: |
295 | |
296 | HV* newHV(); |
297 | |
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298 | Once the HV has been created, the following operations are possible on HVs: |
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299 | |
300 | SV** hv_store(HV*, char* key, U32 klen, SV* val, U32 hash); |
301 | SV** hv_fetch(HV*, char* key, U32 klen, I32 lval); |
302 | |
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303 | The C<klen> parameter is the length of the key being passed in (Note that |
304 | you cannot pass 0 in as a value of C<klen> to tell Perl to measure the |
305 | length of the key). The C<val> argument contains the SV pointer to the |
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306 | scalar being stored, and C<hash> is the precomputed hash value (zero if |
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307 | you want C<hv_store> to calculate it for you). The C<lval> parameter |
308 | indicates whether this fetch is actually a part of a store operation, in |
309 | which case a new undefined value will be added to the HV with the supplied |
310 | key and C<hv_fetch> will return as if the value had already existed. |
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311 | |
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312 | Remember that C<hv_store> and C<hv_fetch> return C<SV**>'s and not just |
313 | C<SV*>. To access the scalar value, you must first dereference the return |
314 | value. However, you should check to make sure that the return value is |
315 | not NULL before dereferencing it. |
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316 | |
317 | These two functions check if a hash table entry exists, and deletes it. |
318 | |
319 | bool hv_exists(HV*, char* key, U32 klen); |
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320 | SV* hv_delete(HV*, char* key, U32 klen, I32 flags); |
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321 | |
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322 | If C<flags> does not include the C<G_DISCARD> flag then C<hv_delete> will |
323 | create and return a mortal copy of the deleted value. |
324 | |
a0d0e21e |
325 | And more miscellaneous functions: |
326 | |
327 | void hv_clear(HV*); |
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328 | void hv_undef(HV*); |
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329 | |
330 | Like their AV counterparts, C<hv_clear> deletes all the entries in the hash |
331 | table but does not actually delete the hash table. The C<hv_undef> deletes |
332 | both the entries and the hash table itself. |
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333 | |
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334 | Perl keeps the actual data in linked list of structures with a typedef of HE. |
335 | These contain the actual key and value pointers (plus extra administrative |
336 | overhead). The key is a string pointer; the value is an C<SV*>. However, |
337 | once you have an C<HE*>, to get the actual key and value, use the routines |
338 | specified below. |
339 | |
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340 | I32 hv_iterinit(HV*); |
341 | /* Prepares starting point to traverse hash table */ |
342 | HE* hv_iternext(HV*); |
343 | /* Get the next entry, and return a pointer to a |
344 | structure that has both the key and value */ |
345 | char* hv_iterkey(HE* entry, I32* retlen); |
346 | /* Get the key from an HE structure and also return |
347 | the length of the key string */ |
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348 | SV* hv_iterval(HV*, HE* entry); |
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349 | /* Return a SV pointer to the value of the HE |
350 | structure */ |
cb1a09d0 |
351 | SV* hv_iternextsv(HV*, char** key, I32* retlen); |
d1b91892 |
352 | /* This convenience routine combines hv_iternext, |
353 | hv_iterkey, and hv_iterval. The key and retlen |
354 | arguments are return values for the key and its |
355 | length. The value is returned in the SV* argument */ |
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356 | |
357 | If you know the name of a hash variable, you can get a pointer to its HV |
358 | by using the following: |
359 | |
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360 | HV* perl_get_hv("package::varname", FALSE); |
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361 | |
362 | This returns NULL if the variable does not exist. |
363 | |
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364 | The hash algorithm is defined in the C<PERL_HASH(hash, key, klen)> macro: |
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365 | |
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366 | hash = 0; |
ab192400 |
367 | while (klen--) |
368 | hash = (hash * 33) + *key++; |
369 | hash = hash + (hash >> 5); /* after 5.006 */ |
370 | |
371 | The last step was added in version 5.006 to improve distribution of |
372 | lower bits in the resulting hash value. |
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373 | |
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374 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
375 | information on how to use the hash access functions on tied hashes. |
376 | |
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377 | =head2 Hash API Extensions |
378 | |
379 | Beginning with version 5.004, the following functions are also supported: |
380 | |
381 | HE* hv_fetch_ent (HV* tb, SV* key, I32 lval, U32 hash); |
382 | HE* hv_store_ent (HV* tb, SV* key, SV* val, U32 hash); |
383 | |
384 | bool hv_exists_ent (HV* tb, SV* key, U32 hash); |
385 | SV* hv_delete_ent (HV* tb, SV* key, I32 flags, U32 hash); |
386 | |
387 | SV* hv_iterkeysv (HE* entry); |
388 | |
389 | Note that these functions take C<SV*> keys, which simplifies writing |
390 | of extension code that deals with hash structures. These functions |
391 | also allow passing of C<SV*> keys to C<tie> functions without forcing |
392 | you to stringify the keys (unlike the previous set of functions). |
393 | |
394 | They also return and accept whole hash entries (C<HE*>), making their |
395 | use more efficient (since the hash number for a particular string |
396 | doesn't have to be recomputed every time). See L<API LISTING> later in |
397 | this document for detailed descriptions. |
398 | |
399 | The following macros must always be used to access the contents of hash |
400 | entries. Note that the arguments to these macros must be simple |
401 | variables, since they may get evaluated more than once. See |
402 | L<API LISTING> later in this document for detailed descriptions of these |
403 | macros. |
404 | |
405 | HePV(HE* he, STRLEN len) |
406 | HeVAL(HE* he) |
407 | HeHASH(HE* he) |
408 | HeSVKEY(HE* he) |
409 | HeSVKEY_force(HE* he) |
410 | HeSVKEY_set(HE* he, SV* sv) |
411 | |
412 | These two lower level macros are defined, but must only be used when |
413 | dealing with keys that are not C<SV*>s: |
414 | |
415 | HeKEY(HE* he) |
416 | HeKLEN(HE* he) |
417 | |
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418 | Note that both C<hv_store> and C<hv_store_ent> do not increment the |
419 | reference count of the stored C<val>, which is the caller's responsibility. |
420 | If these functions return a NULL value, the caller will usually have to |
421 | decrement the reference count of C<val> to avoid a memory leak. |
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422 | |
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423 | =head2 References |
424 | |
d1b91892 |
425 | References are a special type of scalar that point to other data types |
426 | (including references). |
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427 | |
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428 | To create a reference, use either of the following functions: |
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429 | |
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430 | SV* newRV_inc((SV*) thing); |
431 | SV* newRV_noinc((SV*) thing); |
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432 | |
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433 | The C<thing> argument can be any of an C<SV*>, C<AV*>, or C<HV*>. The |
07fa94a1 |
434 | functions are identical except that C<newRV_inc> increments the reference |
435 | count of the C<thing>, while C<newRV_noinc> does not. For historical |
436 | reasons, C<newRV> is a synonym for C<newRV_inc>. |
437 | |
438 | Once you have a reference, you can use the following macro to dereference |
439 | the reference: |
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440 | |
441 | SvRV(SV*) |
442 | |
443 | then call the appropriate routines, casting the returned C<SV*> to either an |
d1b91892 |
444 | C<AV*> or C<HV*>, if required. |
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445 | |
d1b91892 |
446 | To determine if an SV is a reference, you can use the following macro: |
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447 | |
448 | SvROK(SV*) |
449 | |
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450 | To discover what type of value the reference refers to, use the following |
451 | macro and then check the return value. |
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452 | |
453 | SvTYPE(SvRV(SV*)) |
454 | |
455 | The most useful types that will be returned are: |
456 | |
457 | SVt_IV Scalar |
458 | SVt_NV Scalar |
459 | SVt_PV Scalar |
5f05dabc |
460 | SVt_RV Scalar |
d1b91892 |
461 | SVt_PVAV Array |
462 | SVt_PVHV Hash |
463 | SVt_PVCV Code |
5f05dabc |
464 | SVt_PVGV Glob (possible a file handle) |
465 | SVt_PVMG Blessed or Magical Scalar |
466 | |
467 | See the sv.h header file for more details. |
d1b91892 |
468 | |
cb1a09d0 |
469 | =head2 Blessed References and Class Objects |
470 | |
471 | References are also used to support object-oriented programming. In the |
472 | OO lexicon, an object is simply a reference that has been blessed into a |
473 | package (or class). Once blessed, the programmer may now use the reference |
474 | to access the various methods in the class. |
475 | |
476 | A reference can be blessed into a package with the following function: |
477 | |
478 | SV* sv_bless(SV* sv, HV* stash); |
479 | |
480 | The C<sv> argument must be a reference. The C<stash> argument specifies |
3fe9a6f1 |
481 | which class the reference will belong to. See |
2ae324a7 |
482 | L<Stashes and Globs> for information on converting class names into stashes. |
cb1a09d0 |
483 | |
484 | /* Still under construction */ |
485 | |
486 | Upgrades rv to reference if not already one. Creates new SV for rv to |
8ebc5c01 |
487 | point to. If C<classname> is non-null, the SV is blessed into the specified |
488 | class. SV is returned. |
cb1a09d0 |
489 | |
490 | SV* newSVrv(SV* rv, char* classname); |
491 | |
8ebc5c01 |
492 | Copies integer or double into an SV whose reference is C<rv>. SV is blessed |
493 | if C<classname> is non-null. |
cb1a09d0 |
494 | |
495 | SV* sv_setref_iv(SV* rv, char* classname, IV iv); |
496 | SV* sv_setref_nv(SV* rv, char* classname, NV iv); |
497 | |
5f05dabc |
498 | Copies the pointer value (I<the address, not the string!>) into an SV whose |
8ebc5c01 |
499 | reference is rv. SV is blessed if C<classname> is non-null. |
cb1a09d0 |
500 | |
501 | SV* sv_setref_pv(SV* rv, char* classname, PV iv); |
502 | |
8ebc5c01 |
503 | Copies string into an SV whose reference is C<rv>. Set length to 0 to let |
504 | Perl calculate the string length. SV is blessed if C<classname> is non-null. |
cb1a09d0 |
505 | |
506 | SV* sv_setref_pvn(SV* rv, char* classname, PV iv, int length); |
507 | |
9abd00ed |
508 | Tests whether the SV is blessed into the specified class. It does not |
509 | check inheritance relationships. |
510 | |
511 | int sv_isa(SV* sv, char* name); |
512 | |
513 | Tests whether the SV is a reference to a blessed object. |
514 | |
515 | int sv_isobject(SV* sv); |
516 | |
517 | Tests whether the SV is derived from the specified class. SV can be either |
518 | a reference to a blessed object or a string containing a class name. This |
519 | is the function implementing the C<UNIVERSAL::isa> functionality. |
520 | |
521 | bool sv_derived_from(SV* sv, char* name); |
522 | |
523 | To check if you've got an object derived from a specific class you have |
524 | to write: |
525 | |
526 | if (sv_isobject(sv) && sv_derived_from(sv, class)) { ... } |
cb1a09d0 |
527 | |
5f05dabc |
528 | =head2 Creating New Variables |
cb1a09d0 |
529 | |
5f05dabc |
530 | To create a new Perl variable with an undef value which can be accessed from |
531 | your Perl script, use the following routines, depending on the variable type. |
cb1a09d0 |
532 | |
5f05dabc |
533 | SV* perl_get_sv("package::varname", TRUE); |
534 | AV* perl_get_av("package::varname", TRUE); |
535 | HV* perl_get_hv("package::varname", TRUE); |
cb1a09d0 |
536 | |
537 | Notice the use of TRUE as the second parameter. The new variable can now |
538 | be set, using the routines appropriate to the data type. |
539 | |
5f05dabc |
540 | There are additional macros whose values may be bitwise OR'ed with the |
541 | C<TRUE> argument to enable certain extra features. Those bits are: |
cb1a09d0 |
542 | |
5f05dabc |
543 | GV_ADDMULTI Marks the variable as multiply defined, thus preventing the |
54310121 |
544 | "Name <varname> used only once: possible typo" warning. |
07fa94a1 |
545 | GV_ADDWARN Issues the warning "Had to create <varname> unexpectedly" if |
546 | the variable did not exist before the function was called. |
cb1a09d0 |
547 | |
07fa94a1 |
548 | If you do not specify a package name, the variable is created in the current |
549 | package. |
cb1a09d0 |
550 | |
5f05dabc |
551 | =head2 Reference Counts and Mortality |
a0d0e21e |
552 | |
54310121 |
553 | Perl uses an reference count-driven garbage collection mechanism. SVs, |
554 | AVs, or HVs (xV for short in the following) start their life with a |
55497cff |
555 | reference count of 1. If the reference count of an xV ever drops to 0, |
07fa94a1 |
556 | then it will be destroyed and its memory made available for reuse. |
55497cff |
557 | |
558 | This normally doesn't happen at the Perl level unless a variable is |
5f05dabc |
559 | undef'ed or the last variable holding a reference to it is changed or |
560 | overwritten. At the internal level, however, reference counts can be |
55497cff |
561 | manipulated with the following macros: |
562 | |
563 | int SvREFCNT(SV* sv); |
5f05dabc |
564 | SV* SvREFCNT_inc(SV* sv); |
55497cff |
565 | void SvREFCNT_dec(SV* sv); |
566 | |
567 | However, there is one other function which manipulates the reference |
07fa94a1 |
568 | count of its argument. The C<newRV_inc> function, you will recall, |
569 | creates a reference to the specified argument. As a side effect, |
570 | it increments the argument's reference count. If this is not what |
571 | you want, use C<newRV_noinc> instead. |
572 | |
573 | For example, imagine you want to return a reference from an XSUB function. |
574 | Inside the XSUB routine, you create an SV which initially has a reference |
575 | count of one. Then you call C<newRV_inc>, passing it the just-created SV. |
5f05dabc |
576 | This returns the reference as a new SV, but the reference count of the |
577 | SV you passed to C<newRV_inc> has been incremented to two. Now you |
07fa94a1 |
578 | return the reference from the XSUB routine and forget about the SV. |
579 | But Perl hasn't! Whenever the returned reference is destroyed, the |
580 | reference count of the original SV is decreased to one and nothing happens. |
581 | The SV will hang around without any way to access it until Perl itself |
582 | terminates. This is a memory leak. |
5f05dabc |
583 | |
584 | The correct procedure, then, is to use C<newRV_noinc> instead of |
faed5253 |
585 | C<newRV_inc>. Then, if and when the last reference is destroyed, |
586 | the reference count of the SV will go to zero and it will be destroyed, |
07fa94a1 |
587 | stopping any memory leak. |
55497cff |
588 | |
5f05dabc |
589 | There are some convenience functions available that can help with the |
54310121 |
590 | destruction of xVs. These functions introduce the concept of "mortality". |
07fa94a1 |
591 | An xV that is mortal has had its reference count marked to be decremented, |
592 | but not actually decremented, until "a short time later". Generally the |
593 | term "short time later" means a single Perl statement, such as a call to |
54310121 |
594 | an XSUB function. The actual determinant for when mortal xVs have their |
07fa94a1 |
595 | reference count decremented depends on two macros, SAVETMPS and FREETMPS. |
596 | See L<perlcall> and L<perlxs> for more details on these macros. |
55497cff |
597 | |
598 | "Mortalization" then is at its simplest a deferred C<SvREFCNT_dec>. |
599 | However, if you mortalize a variable twice, the reference count will |
600 | later be decremented twice. |
601 | |
602 | You should be careful about creating mortal variables. Strange things |
603 | can happen if you make the same value mortal within multiple contexts, |
5f05dabc |
604 | or if you make a variable mortal multiple times. |
a0d0e21e |
605 | |
606 | To create a mortal variable, use the functions: |
607 | |
608 | SV* sv_newmortal() |
609 | SV* sv_2mortal(SV*) |
610 | SV* sv_mortalcopy(SV*) |
611 | |
5f05dabc |
612 | The first call creates a mortal SV, the second converts an existing |
613 | SV to a mortal SV (and thus defers a call to C<SvREFCNT_dec>), and the |
614 | third creates a mortal copy of an existing SV. |
a0d0e21e |
615 | |
54310121 |
616 | The mortal routines are not just for SVs -- AVs and HVs can be |
faed5253 |
617 | made mortal by passing their address (type-casted to C<SV*>) to the |
07fa94a1 |
618 | C<sv_2mortal> or C<sv_mortalcopy> routines. |
a0d0e21e |
619 | |
5f05dabc |
620 | =head2 Stashes and Globs |
a0d0e21e |
621 | |
aa689395 |
622 | A "stash" is a hash that contains all of the different objects that |
623 | are contained within a package. Each key of the stash is a symbol |
624 | name (shared by all the different types of objects that have the same |
625 | name), and each value in the hash table is a GV (Glob Value). This GV |
626 | in turn contains references to the various objects of that name, |
627 | including (but not limited to) the following: |
cb1a09d0 |
628 | |
a0d0e21e |
629 | Scalar Value |
630 | Array Value |
631 | Hash Value |
a3cb178b |
632 | I/O Handle |
a0d0e21e |
633 | Format |
634 | Subroutine |
635 | |
9cde0e7f |
636 | There is a single stash called "PL_defstash" that holds the items that exist |
5f05dabc |
637 | in the "main" package. To get at the items in other packages, append the |
638 | string "::" to the package name. The items in the "Foo" package are in |
9cde0e7f |
639 | the stash "Foo::" in PL_defstash. The items in the "Bar::Baz" package are |
5f05dabc |
640 | in the stash "Baz::" in "Bar::"'s stash. |
a0d0e21e |
641 | |
d1b91892 |
642 | To get the stash pointer for a particular package, use the function: |
a0d0e21e |
643 | |
644 | HV* gv_stashpv(char* name, I32 create) |
645 | HV* gv_stashsv(SV*, I32 create) |
646 | |
647 | The first function takes a literal string, the second uses the string stored |
d1b91892 |
648 | in the SV. Remember that a stash is just a hash table, so you get back an |
cb1a09d0 |
649 | C<HV*>. The C<create> flag will create a new package if it is set. |
a0d0e21e |
650 | |
651 | The name that C<gv_stash*v> wants is the name of the package whose symbol table |
652 | you want. The default package is called C<main>. If you have multiply nested |
d1b91892 |
653 | packages, pass their names to C<gv_stash*v>, separated by C<::> as in the Perl |
654 | language itself. |
a0d0e21e |
655 | |
656 | Alternately, if you have an SV that is a blessed reference, you can find |
657 | out the stash pointer by using: |
658 | |
659 | HV* SvSTASH(SvRV(SV*)); |
660 | |
661 | then use the following to get the package name itself: |
662 | |
663 | char* HvNAME(HV* stash); |
664 | |
5f05dabc |
665 | If you need to bless or re-bless an object you can use the following |
666 | function: |
a0d0e21e |
667 | |
668 | SV* sv_bless(SV*, HV* stash) |
669 | |
670 | where the first argument, an C<SV*>, must be a reference, and the second |
671 | argument is a stash. The returned C<SV*> can now be used in the same way |
672 | as any other SV. |
673 | |
d1b91892 |
674 | For more information on references and blessings, consult L<perlref>. |
675 | |
54310121 |
676 | =head2 Double-Typed SVs |
0a753a76 |
677 | |
678 | Scalar variables normally contain only one type of value, an integer, |
679 | double, pointer, or reference. Perl will automatically convert the |
680 | actual scalar data from the stored type into the requested type. |
681 | |
682 | Some scalar variables contain more than one type of scalar data. For |
683 | example, the variable C<$!> contains either the numeric value of C<errno> |
684 | or its string equivalent from either C<strerror> or C<sys_errlist[]>. |
685 | |
686 | To force multiple data values into an SV, you must do two things: use the |
687 | C<sv_set*v> routines to add the additional scalar type, then set a flag |
688 | so that Perl will believe it contains more than one type of data. The |
689 | four macros to set the flags are: |
690 | |
691 | SvIOK_on |
692 | SvNOK_on |
693 | SvPOK_on |
694 | SvROK_on |
695 | |
696 | The particular macro you must use depends on which C<sv_set*v> routine |
697 | you called first. This is because every C<sv_set*v> routine turns on |
698 | only the bit for the particular type of data being set, and turns off |
699 | all the rest. |
700 | |
701 | For example, to create a new Perl variable called "dberror" that contains |
702 | both the numeric and descriptive string error values, you could use the |
703 | following code: |
704 | |
705 | extern int dberror; |
706 | extern char *dberror_list; |
707 | |
708 | SV* sv = perl_get_sv("dberror", TRUE); |
709 | sv_setiv(sv, (IV) dberror); |
710 | sv_setpv(sv, dberror_list[dberror]); |
711 | SvIOK_on(sv); |
712 | |
713 | If the order of C<sv_setiv> and C<sv_setpv> had been reversed, then the |
714 | macro C<SvPOK_on> would need to be called instead of C<SvIOK_on>. |
715 | |
716 | =head2 Magic Variables |
a0d0e21e |
717 | |
d1b91892 |
718 | [This section still under construction. Ignore everything here. Post no |
719 | bills. Everything not permitted is forbidden.] |
720 | |
d1b91892 |
721 | Any SV may be magical, that is, it has special features that a normal |
722 | SV does not have. These features are stored in the SV structure in a |
5f05dabc |
723 | linked list of C<struct magic>'s, typedef'ed to C<MAGIC>. |
d1b91892 |
724 | |
725 | struct magic { |
726 | MAGIC* mg_moremagic; |
727 | MGVTBL* mg_virtual; |
728 | U16 mg_private; |
729 | char mg_type; |
730 | U8 mg_flags; |
731 | SV* mg_obj; |
732 | char* mg_ptr; |
733 | I32 mg_len; |
734 | }; |
735 | |
736 | Note this is current as of patchlevel 0, and could change at any time. |
737 | |
738 | =head2 Assigning Magic |
739 | |
740 | Perl adds magic to an SV using the sv_magic function: |
741 | |
742 | void sv_magic(SV* sv, SV* obj, int how, char* name, I32 namlen); |
743 | |
744 | The C<sv> argument is a pointer to the SV that is to acquire a new magical |
745 | feature. |
746 | |
747 | If C<sv> is not already magical, Perl uses the C<SvUPGRADE> macro to |
748 | set the C<SVt_PVMG> flag for the C<sv>. Perl then continues by adding |
749 | it to the beginning of the linked list of magical features. Any prior |
750 | entry of the same type of magic is deleted. Note that this can be |
5fb8527f |
751 | overridden, and multiple instances of the same type of magic can be |
d1b91892 |
752 | associated with an SV. |
753 | |
54310121 |
754 | The C<name> and C<namlen> arguments are used to associate a string with |
755 | the magic, typically the name of a variable. C<namlen> is stored in the |
756 | C<mg_len> field and if C<name> is non-null and C<namlen> >= 0 a malloc'd |
d1b91892 |
757 | copy of the name is stored in C<mg_ptr> field. |
758 | |
759 | The sv_magic function uses C<how> to determine which, if any, predefined |
760 | "Magic Virtual Table" should be assigned to the C<mg_virtual> field. |
cb1a09d0 |
761 | See the "Magic Virtual Table" section below. The C<how> argument is also |
762 | stored in the C<mg_type> field. |
d1b91892 |
763 | |
764 | The C<obj> argument is stored in the C<mg_obj> field of the C<MAGIC> |
765 | structure. If it is not the same as the C<sv> argument, the reference |
766 | count of the C<obj> object is incremented. If it is the same, or if |
04343c6d |
767 | the C<how> argument is "#", or if it is a NULL pointer, then C<obj> is |
d1b91892 |
768 | merely stored, without the reference count being incremented. |
769 | |
cb1a09d0 |
770 | There is also a function to add magic to an C<HV>: |
771 | |
772 | void hv_magic(HV *hv, GV *gv, int how); |
773 | |
774 | This simply calls C<sv_magic> and coerces the C<gv> argument into an C<SV>. |
775 | |
776 | To remove the magic from an SV, call the function sv_unmagic: |
777 | |
778 | void sv_unmagic(SV *sv, int type); |
779 | |
780 | The C<type> argument should be equal to the C<how> value when the C<SV> |
781 | was initially made magical. |
782 | |
d1b91892 |
783 | =head2 Magic Virtual Tables |
784 | |
785 | The C<mg_virtual> field in the C<MAGIC> structure is a pointer to a |
786 | C<MGVTBL>, which is a structure of function pointers and stands for |
787 | "Magic Virtual Table" to handle the various operations that might be |
788 | applied to that variable. |
789 | |
790 | The C<MGVTBL> has five pointers to the following routine types: |
791 | |
792 | int (*svt_get)(SV* sv, MAGIC* mg); |
793 | int (*svt_set)(SV* sv, MAGIC* mg); |
794 | U32 (*svt_len)(SV* sv, MAGIC* mg); |
795 | int (*svt_clear)(SV* sv, MAGIC* mg); |
796 | int (*svt_free)(SV* sv, MAGIC* mg); |
797 | |
798 | This MGVTBL structure is set at compile-time in C<perl.h> and there are |
799 | currently 19 types (or 21 with overloading turned on). These different |
800 | structures contain pointers to various routines that perform additional |
801 | actions depending on which function is being called. |
802 | |
803 | Function pointer Action taken |
804 | ---------------- ------------ |
805 | svt_get Do something after the value of the SV is retrieved. |
806 | svt_set Do something after the SV is assigned a value. |
807 | svt_len Report on the SV's length. |
808 | svt_clear Clear something the SV represents. |
809 | svt_free Free any extra storage associated with the SV. |
810 | |
811 | For instance, the MGVTBL structure called C<vtbl_sv> (which corresponds |
812 | to an C<mg_type> of '\0') contains: |
813 | |
814 | { magic_get, magic_set, magic_len, 0, 0 } |
815 | |
816 | Thus, when an SV is determined to be magical and of type '\0', if a get |
817 | operation is being performed, the routine C<magic_get> is called. All |
818 | the various routines for the various magical types begin with C<magic_>. |
819 | |
820 | The current kinds of Magic Virtual Tables are: |
821 | |
bdbeb323 |
822 | mg_type MGVTBL Type of magic |
5f05dabc |
823 | ------- ------ ---------------------------- |
bdbeb323 |
824 | \0 vtbl_sv Special scalar variable |
825 | A vtbl_amagic %OVERLOAD hash |
826 | a vtbl_amagicelem %OVERLOAD hash element |
827 | c (none) Holds overload table (AMT) on stash |
828 | B vtbl_bm Boyer-Moore (fast string search) |
d1b91892 |
829 | E vtbl_env %ENV hash |
830 | e vtbl_envelem %ENV hash element |
bdbeb323 |
831 | f vtbl_fm Formline ('compiled' format) |
832 | g vtbl_mglob m//g target / study()ed string |
d1b91892 |
833 | I vtbl_isa @ISA array |
834 | i vtbl_isaelem @ISA array element |
bdbeb323 |
835 | k vtbl_nkeys scalar(keys()) lvalue |
836 | L (none) Debugger %_<filename |
837 | l vtbl_dbline Debugger %_<filename element |
44a8e56a |
838 | o vtbl_collxfrm Locale transformation |
bdbeb323 |
839 | P vtbl_pack Tied array or hash |
840 | p vtbl_packelem Tied array or hash element |
841 | q vtbl_packelem Tied scalar or handle |
842 | S vtbl_sig %SIG hash |
843 | s vtbl_sigelem %SIG hash element |
d1b91892 |
844 | t vtbl_taint Taintedness |
bdbeb323 |
845 | U vtbl_uvar Available for use by extensions |
846 | v vtbl_vec vec() lvalue |
847 | x vtbl_substr substr() lvalue |
848 | y vtbl_defelem Shadow "foreach" iterator variable / |
849 | smart parameter vivification |
850 | * vtbl_glob GV (typeglob) |
851 | # vtbl_arylen Array length ($#ary) |
852 | . vtbl_pos pos() lvalue |
853 | ~ (none) Available for use by extensions |
d1b91892 |
854 | |
68dc0745 |
855 | When an uppercase and lowercase letter both exist in the table, then the |
856 | uppercase letter is used to represent some kind of composite type (a list |
857 | or a hash), and the lowercase letter is used to represent an element of |
d1b91892 |
858 | that composite type. |
859 | |
bdbeb323 |
860 | The '~' and 'U' magic types are defined specifically for use by |
861 | extensions and will not be used by perl itself. Extensions can use |
862 | '~' magic to 'attach' private information to variables (typically |
863 | objects). This is especially useful because there is no way for |
864 | normal perl code to corrupt this private information (unlike using |
865 | extra elements of a hash object). |
866 | |
867 | Similarly, 'U' magic can be used much like tie() to call a C function |
868 | any time a scalar's value is used or changed. The C<MAGIC>'s |
869 | C<mg_ptr> field points to a C<ufuncs> structure: |
870 | |
871 | struct ufuncs { |
872 | I32 (*uf_val)(IV, SV*); |
873 | I32 (*uf_set)(IV, SV*); |
874 | IV uf_index; |
875 | }; |
876 | |
877 | When the SV is read from or written to, the C<uf_val> or C<uf_set> |
878 | function will be called with C<uf_index> as the first arg and a |
1526ead6 |
879 | pointer to the SV as the second. A simple example of how to add 'U' |
880 | magic is shown below. Note that the ufuncs structure is copied by |
881 | sv_magic, so you can safely allocate it on the stack. |
882 | |
883 | void |
884 | Umagic(sv) |
885 | SV *sv; |
886 | PREINIT: |
887 | struct ufuncs uf; |
888 | CODE: |
889 | uf.uf_val = &my_get_fn; |
890 | uf.uf_set = &my_set_fn; |
891 | uf.uf_index = 0; |
892 | sv_magic(sv, 0, 'U', (char*)&uf, sizeof(uf)); |
5f05dabc |
893 | |
bdbeb323 |
894 | Note that because multiple extensions may be using '~' or 'U' magic, |
895 | it is important for extensions to take extra care to avoid conflict. |
896 | Typically only using the magic on objects blessed into the same class |
897 | as the extension is sufficient. For '~' magic, it may also be |
898 | appropriate to add an I32 'signature' at the top of the private data |
899 | area and check that. |
5f05dabc |
900 | |
ef50df4b |
901 | Also note that the C<sv_set*()> and C<sv_cat*()> functions described |
902 | earlier do B<not> invoke 'set' magic on their targets. This must |
903 | be done by the user either by calling the C<SvSETMAGIC()> macro after |
904 | calling these functions, or by using one of the C<sv_set*_mg()> or |
905 | C<sv_cat*_mg()> functions. Similarly, generic C code must call the |
906 | C<SvGETMAGIC()> macro to invoke any 'get' magic if they use an SV |
907 | obtained from external sources in functions that don't handle magic. |
908 | L<API LISTING> later in this document identifies such functions. |
189b2af5 |
909 | For example, calls to the C<sv_cat*()> functions typically need to be |
910 | followed by C<SvSETMAGIC()>, but they don't need a prior C<SvGETMAGIC()> |
911 | since their implementation handles 'get' magic. |
912 | |
d1b91892 |
913 | =head2 Finding Magic |
914 | |
915 | MAGIC* mg_find(SV*, int type); /* Finds the magic pointer of that type */ |
916 | |
917 | This routine returns a pointer to the C<MAGIC> structure stored in the SV. |
918 | If the SV does not have that magical feature, C<NULL> is returned. Also, |
54310121 |
919 | if the SV is not of type SVt_PVMG, Perl may core dump. |
d1b91892 |
920 | |
921 | int mg_copy(SV* sv, SV* nsv, char* key, STRLEN klen); |
922 | |
923 | This routine checks to see what types of magic C<sv> has. If the mg_type |
68dc0745 |
924 | field is an uppercase letter, then the mg_obj is copied to C<nsv>, but |
925 | the mg_type field is changed to be the lowercase letter. |
a0d0e21e |
926 | |
04343c6d |
927 | =head2 Understanding the Magic of Tied Hashes and Arrays |
928 | |
929 | Tied hashes and arrays are magical beasts of the 'P' magic type. |
9edb2b46 |
930 | |
931 | WARNING: As of the 5.004 release, proper usage of the array and hash |
932 | access functions requires understanding a few caveats. Some |
933 | of these caveats are actually considered bugs in the API, to be fixed |
934 | in later releases, and are bracketed with [MAYCHANGE] below. If |
935 | you find yourself actually applying such information in this section, be |
936 | aware that the behavior may change in the future, umm, without warning. |
04343c6d |
937 | |
1526ead6 |
938 | The perl tie function associates a variable with an object that implements |
939 | the various GET, SET etc methods. To perform the equivalent of the perl |
940 | tie function from an XSUB, you must mimic this behaviour. The code below |
941 | carries out the necessary steps - firstly it creates a new hash, and then |
942 | creates a second hash which it blesses into the class which will implement |
943 | the tie methods. Lastly it ties the two hashes together, and returns a |
944 | reference to the new tied hash. Note that the code below does NOT call the |
945 | TIEHASH method in the MyTie class - |
946 | see L<Calling Perl Routines from within C Programs> for details on how |
947 | to do this. |
948 | |
949 | SV* |
950 | mytie() |
951 | PREINIT: |
952 | HV *hash; |
953 | HV *stash; |
954 | SV *tie; |
955 | CODE: |
956 | hash = newHV(); |
957 | tie = newRV_noinc((SV*)newHV()); |
958 | stash = gv_stashpv("MyTie", TRUE); |
959 | sv_bless(tie, stash); |
960 | hv_magic(hash, tie, 'P'); |
961 | RETVAL = newRV_noinc(hash); |
962 | OUTPUT: |
963 | RETVAL |
964 | |
04343c6d |
965 | The C<av_store> function, when given a tied array argument, merely |
966 | copies the magic of the array onto the value to be "stored", using |
967 | C<mg_copy>. It may also return NULL, indicating that the value did not |
9edb2b46 |
968 | actually need to be stored in the array. [MAYCHANGE] After a call to |
969 | C<av_store> on a tied array, the caller will usually need to call |
970 | C<mg_set(val)> to actually invoke the perl level "STORE" method on the |
971 | TIEARRAY object. If C<av_store> did return NULL, a call to |
972 | C<SvREFCNT_dec(val)> will also be usually necessary to avoid a memory |
973 | leak. [/MAYCHANGE] |
04343c6d |
974 | |
975 | The previous paragraph is applicable verbatim to tied hash access using the |
976 | C<hv_store> and C<hv_store_ent> functions as well. |
977 | |
978 | C<av_fetch> and the corresponding hash functions C<hv_fetch> and |
979 | C<hv_fetch_ent> actually return an undefined mortal value whose magic |
980 | has been initialized using C<mg_copy>. Note the value so returned does not |
9edb2b46 |
981 | need to be deallocated, as it is already mortal. [MAYCHANGE] But you will |
982 | need to call C<mg_get()> on the returned value in order to actually invoke |
983 | the perl level "FETCH" method on the underlying TIE object. Similarly, |
04343c6d |
984 | you may also call C<mg_set()> on the return value after possibly assigning |
985 | a suitable value to it using C<sv_setsv>, which will invoke the "STORE" |
9edb2b46 |
986 | method on the TIE object. [/MAYCHANGE] |
04343c6d |
987 | |
9edb2b46 |
988 | [MAYCHANGE] |
04343c6d |
989 | In other words, the array or hash fetch/store functions don't really |
990 | fetch and store actual values in the case of tied arrays and hashes. They |
991 | merely call C<mg_copy> to attach magic to the values that were meant to be |
992 | "stored" or "fetched". Later calls to C<mg_get> and C<mg_set> actually |
993 | do the job of invoking the TIE methods on the underlying objects. Thus |
9edb2b46 |
994 | the magic mechanism currently implements a kind of lazy access to arrays |
04343c6d |
995 | and hashes. |
996 | |
997 | Currently (as of perl version 5.004), use of the hash and array access |
998 | functions requires the user to be aware of whether they are operating on |
9edb2b46 |
999 | "normal" hashes and arrays, or on their tied variants. The API may be |
1000 | changed to provide more transparent access to both tied and normal data |
1001 | types in future versions. |
1002 | [/MAYCHANGE] |
04343c6d |
1003 | |
1004 | You would do well to understand that the TIEARRAY and TIEHASH interfaces |
1005 | are mere sugar to invoke some perl method calls while using the uniform hash |
1006 | and array syntax. The use of this sugar imposes some overhead (typically |
1007 | about two to four extra opcodes per FETCH/STORE operation, in addition to |
1008 | the creation of all the mortal variables required to invoke the methods). |
1009 | This overhead will be comparatively small if the TIE methods are themselves |
1010 | substantial, but if they are only a few statements long, the overhead |
1011 | will not be insignificant. |
1012 | |
d1c897a1 |
1013 | =head2 Localizing changes |
1014 | |
1015 | Perl has a very handy construction |
1016 | |
1017 | { |
1018 | local $var = 2; |
1019 | ... |
1020 | } |
1021 | |
1022 | This construction is I<approximately> equivalent to |
1023 | |
1024 | { |
1025 | my $oldvar = $var; |
1026 | $var = 2; |
1027 | ... |
1028 | $var = $oldvar; |
1029 | } |
1030 | |
1031 | The biggest difference is that the first construction would |
1032 | reinstate the initial value of $var, irrespective of how control exits |
1033 | the block: C<goto>, C<return>, C<die>/C<eval> etc. It is a little bit |
1034 | more efficient as well. |
1035 | |
1036 | There is a way to achieve a similar task from C via Perl API: create a |
1037 | I<pseudo-block>, and arrange for some changes to be automatically |
1038 | undone at the end of it, either explicit, or via a non-local exit (via |
1039 | die()). A I<block>-like construct is created by a pair of |
b687b08b |
1040 | C<ENTER>/C<LEAVE> macros (see L<perlcall/"Returning a Scalar">). |
1041 | Such a construct may be created specially for some important localized |
1042 | task, or an existing one (like boundaries of enclosing Perl |
1043 | subroutine/block, or an existing pair for freeing TMPs) may be |
1044 | used. (In the second case the overhead of additional localization must |
1045 | be almost negligible.) Note that any XSUB is automatically enclosed in |
1046 | an C<ENTER>/C<LEAVE> pair. |
d1c897a1 |
1047 | |
1048 | Inside such a I<pseudo-block> the following service is available: |
1049 | |
1050 | =over |
1051 | |
1052 | =item C<SAVEINT(int i)> |
1053 | |
1054 | =item C<SAVEIV(IV i)> |
1055 | |
1056 | =item C<SAVEI32(I32 i)> |
1057 | |
1058 | =item C<SAVELONG(long i)> |
1059 | |
1060 | These macros arrange things to restore the value of integer variable |
1061 | C<i> at the end of enclosing I<pseudo-block>. |
1062 | |
1063 | =item C<SAVESPTR(s)> |
1064 | |
1065 | =item C<SAVEPPTR(p)> |
1066 | |
1067 | These macros arrange things to restore the value of pointers C<s> and |
1068 | C<p>. C<s> must be a pointer of a type which survives conversion to |
1069 | C<SV*> and back, C<p> should be able to survive conversion to C<char*> |
1070 | and back. |
1071 | |
1072 | =item C<SAVEFREESV(SV *sv)> |
1073 | |
1074 | The refcount of C<sv> would be decremented at the end of |
1075 | I<pseudo-block>. This is similar to C<sv_2mortal>, which should (?) be |
1076 | used instead. |
1077 | |
1078 | =item C<SAVEFREEOP(OP *op)> |
1079 | |
1080 | The C<OP *> is op_free()ed at the end of I<pseudo-block>. |
1081 | |
1082 | =item C<SAVEFREEPV(p)> |
1083 | |
1084 | The chunk of memory which is pointed to by C<p> is Safefree()ed at the |
1085 | end of I<pseudo-block>. |
1086 | |
1087 | =item C<SAVECLEARSV(SV *sv)> |
1088 | |
1089 | Clears a slot in the current scratchpad which corresponds to C<sv> at |
1090 | the end of I<pseudo-block>. |
1091 | |
1092 | =item C<SAVEDELETE(HV *hv, char *key, I32 length)> |
1093 | |
1094 | The key C<key> of C<hv> is deleted at the end of I<pseudo-block>. The |
1095 | string pointed to by C<key> is Safefree()ed. If one has a I<key> in |
1096 | short-lived storage, the corresponding string may be reallocated like |
1097 | this: |
1098 | |
9cde0e7f |
1099 | SAVEDELETE(PL_defstash, savepv(tmpbuf), strlen(tmpbuf)); |
d1c897a1 |
1100 | |
1101 | =item C<SAVEDESTRUCTOR(f,p)> |
1102 | |
1103 | At the end of I<pseudo-block> the function C<f> is called with the |
1104 | only argument (of type C<void*>) C<p>. |
1105 | |
1106 | =item C<SAVESTACK_POS()> |
1107 | |
1108 | The current offset on the Perl internal stack (cf. C<SP>) is restored |
1109 | at the end of I<pseudo-block>. |
1110 | |
1111 | =back |
1112 | |
1113 | The following API list contains functions, thus one needs to |
1114 | provide pointers to the modifiable data explicitly (either C pointers, |
1115 | or Perlish C<GV *>s). Where the above macros take C<int>, a similar |
1116 | function takes C<int *>. |
1117 | |
1118 | =over |
1119 | |
1120 | =item C<SV* save_scalar(GV *gv)> |
1121 | |
1122 | Equivalent to Perl code C<local $gv>. |
1123 | |
1124 | =item C<AV* save_ary(GV *gv)> |
1125 | |
1126 | =item C<HV* save_hash(GV *gv)> |
1127 | |
1128 | Similar to C<save_scalar>, but localize C<@gv> and C<%gv>. |
1129 | |
1130 | =item C<void save_item(SV *item)> |
1131 | |
1132 | Duplicates the current value of C<SV>, on the exit from the current |
1133 | C<ENTER>/C<LEAVE> I<pseudo-block> will restore the value of C<SV> |
1134 | using the stored value. |
1135 | |
1136 | =item C<void save_list(SV **sarg, I32 maxsarg)> |
1137 | |
1138 | A variant of C<save_item> which takes multiple arguments via an array |
1139 | C<sarg> of C<SV*> of length C<maxsarg>. |
1140 | |
1141 | =item C<SV* save_svref(SV **sptr)> |
1142 | |
1143 | Similar to C<save_scalar>, but will reinstate a C<SV *>. |
1144 | |
1145 | =item C<void save_aptr(AV **aptr)> |
1146 | |
1147 | =item C<void save_hptr(HV **hptr)> |
1148 | |
1149 | Similar to C<save_svref>, but localize C<AV *> and C<HV *>. |
1150 | |
1151 | =back |
1152 | |
1153 | The C<Alias> module implements localization of the basic types within the |
1154 | I<caller's scope>. People who are interested in how to localize things in |
1155 | the containing scope should take a look there too. |
1156 | |
0a753a76 |
1157 | =head1 Subroutines |
a0d0e21e |
1158 | |
68dc0745 |
1159 | =head2 XSUBs and the Argument Stack |
5f05dabc |
1160 | |
1161 | The XSUB mechanism is a simple way for Perl programs to access C subroutines. |
1162 | An XSUB routine will have a stack that contains the arguments from the Perl |
1163 | program, and a way to map from the Perl data structures to a C equivalent. |
1164 | |
1165 | The stack arguments are accessible through the C<ST(n)> macro, which returns |
1166 | the C<n>'th stack argument. Argument 0 is the first argument passed in the |
1167 | Perl subroutine call. These arguments are C<SV*>, and can be used anywhere |
1168 | an C<SV*> is used. |
1169 | |
1170 | Most of the time, output from the C routine can be handled through use of |
1171 | the RETVAL and OUTPUT directives. However, there are some cases where the |
1172 | argument stack is not already long enough to handle all the return values. |
1173 | An example is the POSIX tzname() call, which takes no arguments, but returns |
1174 | two, the local time zone's standard and summer time abbreviations. |
1175 | |
1176 | To handle this situation, the PPCODE directive is used and the stack is |
1177 | extended using the macro: |
1178 | |
924508f0 |
1179 | EXTEND(SP, num); |
5f05dabc |
1180 | |
924508f0 |
1181 | where C<SP> is the macro that represents the local copy of the stack pointer, |
1182 | and C<num> is the number of elements the stack should be extended by. |
5f05dabc |
1183 | |
1184 | Now that there is room on the stack, values can be pushed on it using the |
54310121 |
1185 | macros to push IVs, doubles, strings, and SV pointers respectively: |
5f05dabc |
1186 | |
1187 | PUSHi(IV) |
1188 | PUSHn(double) |
1189 | PUSHp(char*, I32) |
1190 | PUSHs(SV*) |
1191 | |
1192 | And now the Perl program calling C<tzname>, the two values will be assigned |
1193 | as in: |
1194 | |
1195 | ($standard_abbrev, $summer_abbrev) = POSIX::tzname; |
1196 | |
1197 | An alternate (and possibly simpler) method to pushing values on the stack is |
1198 | to use the macros: |
1199 | |
1200 | XPUSHi(IV) |
1201 | XPUSHn(double) |
1202 | XPUSHp(char*, I32) |
1203 | XPUSHs(SV*) |
1204 | |
1205 | These macros automatically adjust the stack for you, if needed. Thus, you |
1206 | do not need to call C<EXTEND> to extend the stack. |
1207 | |
1208 | For more information, consult L<perlxs> and L<perlxstut>. |
1209 | |
1210 | =head2 Calling Perl Routines from within C Programs |
a0d0e21e |
1211 | |
1212 | There are four routines that can be used to call a Perl subroutine from |
1213 | within a C program. These four are: |
1214 | |
1215 | I32 perl_call_sv(SV*, I32); |
1216 | I32 perl_call_pv(char*, I32); |
1217 | I32 perl_call_method(char*, I32); |
1218 | I32 perl_call_argv(char*, I32, register char**); |
1219 | |
d1b91892 |
1220 | The routine most often used is C<perl_call_sv>. The C<SV*> argument |
1221 | contains either the name of the Perl subroutine to be called, or a |
1222 | reference to the subroutine. The second argument consists of flags |
1223 | that control the context in which the subroutine is called, whether |
1224 | or not the subroutine is being passed arguments, how errors should be |
1225 | trapped, and how to treat return values. |
a0d0e21e |
1226 | |
1227 | All four routines return the number of arguments that the subroutine returned |
1228 | on the Perl stack. |
1229 | |
d1b91892 |
1230 | When using any of these routines (except C<perl_call_argv>), the programmer |
1231 | must manipulate the Perl stack. These include the following macros and |
1232 | functions: |
a0d0e21e |
1233 | |
1234 | dSP |
924508f0 |
1235 | SP |
a0d0e21e |
1236 | PUSHMARK() |
1237 | PUTBACK |
1238 | SPAGAIN |
1239 | ENTER |
1240 | SAVETMPS |
1241 | FREETMPS |
1242 | LEAVE |
1243 | XPUSH*() |
cb1a09d0 |
1244 | POP*() |
a0d0e21e |
1245 | |
5f05dabc |
1246 | For a detailed description of calling conventions from C to Perl, |
1247 | consult L<perlcall>. |
a0d0e21e |
1248 | |
5f05dabc |
1249 | =head2 Memory Allocation |
a0d0e21e |
1250 | |
86058a2d |
1251 | All memory meant to be used with the Perl API functions should be manipulated |
1252 | using the macros described in this section. The macros provide the necessary |
1253 | transparency between differences in the actual malloc implementation that is |
1254 | used within perl. |
1255 | |
1256 | It is suggested that you enable the version of malloc that is distributed |
5f05dabc |
1257 | with Perl. It keeps pools of various sizes of unallocated memory in |
07fa94a1 |
1258 | order to satisfy allocation requests more quickly. However, on some |
1259 | platforms, it may cause spurious malloc or free errors. |
d1b91892 |
1260 | |
1261 | New(x, pointer, number, type); |
1262 | Newc(x, pointer, number, type, cast); |
1263 | Newz(x, pointer, number, type); |
1264 | |
07fa94a1 |
1265 | These three macros are used to initially allocate memory. |
5f05dabc |
1266 | |
1267 | The first argument C<x> was a "magic cookie" that was used to keep track |
1268 | of who called the macro, to help when debugging memory problems. However, |
07fa94a1 |
1269 | the current code makes no use of this feature (most Perl developers now |
1270 | use run-time memory checkers), so this argument can be any number. |
5f05dabc |
1271 | |
1272 | The second argument C<pointer> should be the name of a variable that will |
1273 | point to the newly allocated memory. |
d1b91892 |
1274 | |
d1b91892 |
1275 | The third and fourth arguments C<number> and C<type> specify how many of |
1276 | the specified type of data structure should be allocated. The argument |
1277 | C<type> is passed to C<sizeof>. The final argument to C<Newc>, C<cast>, |
1278 | should be used if the C<pointer> argument is different from the C<type> |
1279 | argument. |
1280 | |
1281 | Unlike the C<New> and C<Newc> macros, the C<Newz> macro calls C<memzero> |
1282 | to zero out all the newly allocated memory. |
1283 | |
1284 | Renew(pointer, number, type); |
1285 | Renewc(pointer, number, type, cast); |
1286 | Safefree(pointer) |
1287 | |
1288 | These three macros are used to change a memory buffer size or to free a |
1289 | piece of memory no longer needed. The arguments to C<Renew> and C<Renewc> |
1290 | match those of C<New> and C<Newc> with the exception of not needing the |
1291 | "magic cookie" argument. |
1292 | |
1293 | Move(source, dest, number, type); |
1294 | Copy(source, dest, number, type); |
1295 | Zero(dest, number, type); |
1296 | |
1297 | These three macros are used to move, copy, or zero out previously allocated |
1298 | memory. The C<source> and C<dest> arguments point to the source and |
1299 | destination starting points. Perl will move, copy, or zero out C<number> |
1300 | instances of the size of the C<type> data structure (using the C<sizeof> |
1301 | function). |
a0d0e21e |
1302 | |
5f05dabc |
1303 | =head2 PerlIO |
ce3d39e2 |
1304 | |
5f05dabc |
1305 | The most recent development releases of Perl has been experimenting with |
1306 | removing Perl's dependency on the "normal" standard I/O suite and allowing |
1307 | other stdio implementations to be used. This involves creating a new |
1308 | abstraction layer that then calls whichever implementation of stdio Perl |
68dc0745 |
1309 | was compiled with. All XSUBs should now use the functions in the PerlIO |
5f05dabc |
1310 | abstraction layer and not make any assumptions about what kind of stdio |
1311 | is being used. |
1312 | |
1313 | For a complete description of the PerlIO abstraction, consult L<perlapio>. |
1314 | |
8ebc5c01 |
1315 | =head2 Putting a C value on Perl stack |
ce3d39e2 |
1316 | |
1317 | A lot of opcodes (this is an elementary operation in the internal perl |
1318 | stack machine) put an SV* on the stack. However, as an optimization |
1319 | the corresponding SV is (usually) not recreated each time. The opcodes |
1320 | reuse specially assigned SVs (I<target>s) which are (as a corollary) |
1321 | not constantly freed/created. |
1322 | |
0a753a76 |
1323 | Each of the targets is created only once (but see |
ce3d39e2 |
1324 | L<Scratchpads and recursion> below), and when an opcode needs to put |
1325 | an integer, a double, or a string on stack, it just sets the |
1326 | corresponding parts of its I<target> and puts the I<target> on stack. |
1327 | |
1328 | The macro to put this target on stack is C<PUSHTARG>, and it is |
1329 | directly used in some opcodes, as well as indirectly in zillions of |
1330 | others, which use it via C<(X)PUSH[pni]>. |
1331 | |
8ebc5c01 |
1332 | =head2 Scratchpads |
ce3d39e2 |
1333 | |
54310121 |
1334 | The question remains on when the SVs which are I<target>s for opcodes |
5f05dabc |
1335 | are created. The answer is that they are created when the current unit -- |
1336 | a subroutine or a file (for opcodes for statements outside of |
1337 | subroutines) -- is compiled. During this time a special anonymous Perl |
ce3d39e2 |
1338 | array is created, which is called a scratchpad for the current |
1339 | unit. |
1340 | |
54310121 |
1341 | A scratchpad keeps SVs which are lexicals for the current unit and are |
ce3d39e2 |
1342 | targets for opcodes. One can deduce that an SV lives on a scratchpad |
1343 | by looking on its flags: lexicals have C<SVs_PADMY> set, and |
1344 | I<target>s have C<SVs_PADTMP> set. |
1345 | |
54310121 |
1346 | The correspondence between OPs and I<target>s is not 1-to-1. Different |
1347 | OPs in the compile tree of the unit can use the same target, if this |
ce3d39e2 |
1348 | would not conflict with the expected life of the temporary. |
1349 | |
2ae324a7 |
1350 | =head2 Scratchpads and recursion |
ce3d39e2 |
1351 | |
1352 | In fact it is not 100% true that a compiled unit contains a pointer to |
1353 | the scratchpad AV. In fact it contains a pointer to an AV of |
1354 | (initially) one element, and this element is the scratchpad AV. Why do |
1355 | we need an extra level of indirection? |
1356 | |
1357 | The answer is B<recursion>, and maybe (sometime soon) B<threads>. Both |
1358 | these can create several execution pointers going into the same |
1359 | subroutine. For the subroutine-child not write over the temporaries |
1360 | for the subroutine-parent (lifespan of which covers the call to the |
1361 | child), the parent and the child should have different |
1362 | scratchpads. (I<And> the lexicals should be separate anyway!) |
1363 | |
5f05dabc |
1364 | So each subroutine is born with an array of scratchpads (of length 1). |
1365 | On each entry to the subroutine it is checked that the current |
ce3d39e2 |
1366 | depth of the recursion is not more than the length of this array, and |
1367 | if it is, new scratchpad is created and pushed into the array. |
1368 | |
1369 | The I<target>s on this scratchpad are C<undef>s, but they are already |
1370 | marked with correct flags. |
1371 | |
0a753a76 |
1372 | =head1 Compiled code |
1373 | |
1374 | =head2 Code tree |
1375 | |
1376 | Here we describe the internal form your code is converted to by |
1377 | Perl. Start with a simple example: |
1378 | |
1379 | $a = $b + $c; |
1380 | |
1381 | This is converted to a tree similar to this one: |
1382 | |
1383 | assign-to |
1384 | / \ |
1385 | + $a |
1386 | / \ |
1387 | $b $c |
1388 | |
7b8d334a |
1389 | (but slightly more complicated). This tree reflects the way Perl |
0a753a76 |
1390 | parsed your code, but has nothing to do with the execution order. |
1391 | There is an additional "thread" going through the nodes of the tree |
1392 | which shows the order of execution of the nodes. In our simplified |
1393 | example above it looks like: |
1394 | |
1395 | $b ---> $c ---> + ---> $a ---> assign-to |
1396 | |
1397 | But with the actual compile tree for C<$a = $b + $c> it is different: |
1398 | some nodes I<optimized away>. As a corollary, though the actual tree |
1399 | contains more nodes than our simplified example, the execution order |
1400 | is the same as in our example. |
1401 | |
1402 | =head2 Examining the tree |
1403 | |
1404 | If you have your perl compiled for debugging (usually done with C<-D |
1405 | optimize=-g> on C<Configure> command line), you may examine the |
1406 | compiled tree by specifying C<-Dx> on the Perl command line. The |
1407 | output takes several lines per node, and for C<$b+$c> it looks like |
1408 | this: |
1409 | |
1410 | 5 TYPE = add ===> 6 |
1411 | TARG = 1 |
1412 | FLAGS = (SCALAR,KIDS) |
1413 | { |
1414 | TYPE = null ===> (4) |
1415 | (was rv2sv) |
1416 | FLAGS = (SCALAR,KIDS) |
1417 | { |
1418 | 3 TYPE = gvsv ===> 4 |
1419 | FLAGS = (SCALAR) |
1420 | GV = main::b |
1421 | } |
1422 | } |
1423 | { |
1424 | TYPE = null ===> (5) |
1425 | (was rv2sv) |
1426 | FLAGS = (SCALAR,KIDS) |
1427 | { |
1428 | 4 TYPE = gvsv ===> 5 |
1429 | FLAGS = (SCALAR) |
1430 | GV = main::c |
1431 | } |
1432 | } |
1433 | |
1434 | This tree has 5 nodes (one per C<TYPE> specifier), only 3 of them are |
1435 | not optimized away (one per number in the left column). The immediate |
1436 | children of the given node correspond to C<{}> pairs on the same level |
1437 | of indentation, thus this listing corresponds to the tree: |
1438 | |
1439 | add |
1440 | / \ |
1441 | null null |
1442 | | | |
1443 | gvsv gvsv |
1444 | |
1445 | The execution order is indicated by C<===E<gt>> marks, thus it is C<3 |
1446 | 4 5 6> (node C<6> is not included into above listing), i.e., |
1447 | C<gvsv gvsv add whatever>. |
1448 | |
1449 | =head2 Compile pass 1: check routines |
1450 | |
1451 | The tree is created by the I<pseudo-compiler> while yacc code feeds it |
1452 | the constructions it recognizes. Since yacc works bottom-up, so does |
1453 | the first pass of perl compilation. |
1454 | |
1455 | What makes this pass interesting for perl developers is that some |
1456 | optimization may be performed on this pass. This is optimization by |
1457 | so-called I<check routines>. The correspondence between node names |
1458 | and corresponding check routines is described in F<opcode.pl> (do not |
1459 | forget to run C<make regen_headers> if you modify this file). |
1460 | |
1461 | A check routine is called when the node is fully constructed except |
7b8d334a |
1462 | for the execution-order thread. Since at this time there are no |
0a753a76 |
1463 | back-links to the currently constructed node, one can do most any |
1464 | operation to the top-level node, including freeing it and/or creating |
1465 | new nodes above/below it. |
1466 | |
1467 | The check routine returns the node which should be inserted into the |
1468 | tree (if the top-level node was not modified, check routine returns |
1469 | its argument). |
1470 | |
1471 | By convention, check routines have names C<ck_*>. They are usually |
1472 | called from C<new*OP> subroutines (or C<convert>) (which in turn are |
1473 | called from F<perly.y>). |
1474 | |
1475 | =head2 Compile pass 1a: constant folding |
1476 | |
1477 | Immediately after the check routine is called the returned node is |
1478 | checked for being compile-time executable. If it is (the value is |
1479 | judged to be constant) it is immediately executed, and a I<constant> |
1480 | node with the "return value" of the corresponding subtree is |
1481 | substituted instead. The subtree is deleted. |
1482 | |
1483 | If constant folding was not performed, the execution-order thread is |
1484 | created. |
1485 | |
1486 | =head2 Compile pass 2: context propagation |
1487 | |
1488 | When a context for a part of compile tree is known, it is propagated |
a3cb178b |
1489 | down through the tree. At this time the context can have 5 values |
0a753a76 |
1490 | (instead of 2 for runtime context): void, boolean, scalar, list, and |
1491 | lvalue. In contrast with the pass 1 this pass is processed from top |
1492 | to bottom: a node's context determines the context for its children. |
1493 | |
1494 | Additional context-dependent optimizations are performed at this time. |
1495 | Since at this moment the compile tree contains back-references (via |
1496 | "thread" pointers), nodes cannot be free()d now. To allow |
1497 | optimized-away nodes at this stage, such nodes are null()ified instead |
1498 | of free()ing (i.e. their type is changed to OP_NULL). |
1499 | |
1500 | =head2 Compile pass 3: peephole optimization |
1501 | |
1502 | After the compile tree for a subroutine (or for an C<eval> or a file) |
1503 | is created, an additional pass over the code is performed. This pass |
1504 | is neither top-down or bottom-up, but in the execution order (with |
7b8d334a |
1505 | additional complications for conditionals). These optimizations are |
0a753a76 |
1506 | done in the subroutine peep(). Optimizations performed at this stage |
1507 | are subject to the same restrictions as in the pass 2. |
1508 | |
1509 | =head1 API LISTING |
a0d0e21e |
1510 | |
cb1a09d0 |
1511 | This is a listing of functions, macros, flags, and variables that may be |
1512 | useful to extension writers or that may be found while reading other |
1513 | extensions. |
9cde0e7f |
1514 | |
1515 | Note that all Perl API global variables must be referenced with the C<PL_> |
1516 | prefix. Some macros are provided for compatibility with the older, |
1517 | unadorned names, but this support will be removed in a future release. |
1518 | |
1519 | It is strongly recommended that all Perl API functions that don't begin |
1520 | with C<perl> be referenced with an explicit C<Perl_> prefix. |
1521 | |
e89caa19 |
1522 | The sort order of the listing is case insensitive, with any |
b5a41e52 |
1523 | occurrences of '_' ignored for the purpose of sorting. |
a0d0e21e |
1524 | |
cb1a09d0 |
1525 | =over 8 |
a0d0e21e |
1526 | |
cb1a09d0 |
1527 | =item av_clear |
1528 | |
0146554f |
1529 | Clears an array, making it empty. Does not free the memory used by the |
1530 | array itself. |
cb1a09d0 |
1531 | |
ef50df4b |
1532 | void av_clear (AV* ar) |
cb1a09d0 |
1533 | |
1534 | =item av_extend |
1535 | |
1536 | Pre-extend an array. The C<key> is the index to which the array should be |
1537 | extended. |
1538 | |
ef50df4b |
1539 | void av_extend (AV* ar, I32 key) |
cb1a09d0 |
1540 | |
1541 | =item av_fetch |
1542 | |
1543 | Returns the SV at the specified index in the array. The C<key> is the |
1544 | index. If C<lval> is set then the fetch will be part of a store. Check |
1545 | that the return value is non-null before dereferencing it to a C<SV*>. |
1546 | |
04343c6d |
1547 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1548 | information on how to use this function on tied arrays. |
1549 | |
ef50df4b |
1550 | SV** av_fetch (AV* ar, I32 key, I32 lval) |
cb1a09d0 |
1551 | |
e89caa19 |
1552 | =item AvFILL |
1553 | |
95906810 |
1554 | Same as C<av_len()>. Deprecated, use C<av_len()> instead. |
e89caa19 |
1555 | |
cb1a09d0 |
1556 | =item av_len |
1557 | |
1558 | Returns the highest index in the array. Returns -1 if the array is empty. |
1559 | |
ef50df4b |
1560 | I32 av_len (AV* ar) |
cb1a09d0 |
1561 | |
1562 | =item av_make |
1563 | |
5fb8527f |
1564 | Creates a new AV and populates it with a list of SVs. The SVs are copied |
1565 | into the array, so they may be freed after the call to av_make. The new AV |
5f05dabc |
1566 | will have a reference count of 1. |
cb1a09d0 |
1567 | |
ef50df4b |
1568 | AV* av_make (I32 size, SV** svp) |
cb1a09d0 |
1569 | |
1570 | =item av_pop |
1571 | |
9cde0e7f |
1572 | Pops an SV off the end of the array. Returns C<&PL_sv_undef> if the array is |
cb1a09d0 |
1573 | empty. |
1574 | |
ef50df4b |
1575 | SV* av_pop (AV* ar) |
cb1a09d0 |
1576 | |
1577 | =item av_push |
1578 | |
5fb8527f |
1579 | Pushes an SV onto the end of the array. The array will grow automatically |
1580 | to accommodate the addition. |
cb1a09d0 |
1581 | |
ef50df4b |
1582 | void av_push (AV* ar, SV* val) |
cb1a09d0 |
1583 | |
1584 | =item av_shift |
1585 | |
1586 | Shifts an SV off the beginning of the array. |
1587 | |
ef50df4b |
1588 | SV* av_shift (AV* ar) |
cb1a09d0 |
1589 | |
1590 | =item av_store |
1591 | |
1592 | Stores an SV in an array. The array index is specified as C<key>. The |
04343c6d |
1593 | return value will be NULL if the operation failed or if the value did not |
1594 | need to be actually stored within the array (as in the case of tied arrays). |
1595 | Otherwise it can be dereferenced to get the original C<SV*>. Note that the |
1596 | caller is responsible for suitably incrementing the reference count of C<val> |
1597 | before the call, and decrementing it if the function returned NULL. |
1598 | |
1599 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1600 | information on how to use this function on tied arrays. |
cb1a09d0 |
1601 | |
ef50df4b |
1602 | SV** av_store (AV* ar, I32 key, SV* val) |
cb1a09d0 |
1603 | |
1604 | =item av_undef |
1605 | |
0146554f |
1606 | Undefines the array. Frees the memory used by the array itself. |
cb1a09d0 |
1607 | |
ef50df4b |
1608 | void av_undef (AV* ar) |
cb1a09d0 |
1609 | |
1610 | =item av_unshift |
1611 | |
0146554f |
1612 | Unshift the given number of C<undef> values onto the beginning of the |
1613 | array. The array will grow automatically to accommodate the addition. |
1614 | You must then use C<av_store> to assign values to these new elements. |
cb1a09d0 |
1615 | |
ef50df4b |
1616 | void av_unshift (AV* ar, I32 num) |
cb1a09d0 |
1617 | |
1618 | =item CLASS |
1619 | |
1620 | Variable which is setup by C<xsubpp> to indicate the class name for a C++ XS |
5fb8527f |
1621 | constructor. This is always a C<char*>. See C<THIS> and |
1622 | L<perlxs/"Using XS With C++">. |
cb1a09d0 |
1623 | |
1624 | =item Copy |
1625 | |
1626 | The XSUB-writer's interface to the C C<memcpy> function. The C<s> is the |
1627 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
0146554f |
1628 | the type. May fail on overlapping copies. See also C<Move>. |
cb1a09d0 |
1629 | |
e89caa19 |
1630 | void Copy( s, d, n, t ) |
cb1a09d0 |
1631 | |
1632 | =item croak |
1633 | |
1634 | This is the XSUB-writer's interface to Perl's C<die> function. Use this |
1635 | function the same way you use the C C<printf> function. See C<warn>. |
1636 | |
1637 | =item CvSTASH |
1638 | |
1639 | Returns the stash of the CV. |
1640 | |
e89caa19 |
1641 | HV* CvSTASH( SV* sv ) |
cb1a09d0 |
1642 | |
9cde0e7f |
1643 | =item PL_DBsingle |
cb1a09d0 |
1644 | |
1645 | When Perl is run in debugging mode, with the B<-d> switch, this SV is a |
1646 | boolean which indicates whether subs are being single-stepped. |
5fb8527f |
1647 | Single-stepping is automatically turned on after every step. This is the C |
9cde0e7f |
1648 | variable which corresponds to Perl's $DB::single variable. See C<PL_DBsub>. |
cb1a09d0 |
1649 | |
9cde0e7f |
1650 | =item PL_DBsub |
cb1a09d0 |
1651 | |
1652 | When Perl is run in debugging mode, with the B<-d> switch, this GV contains |
5fb8527f |
1653 | the SV which holds the name of the sub being debugged. This is the C |
9cde0e7f |
1654 | variable which corresponds to Perl's $DB::sub variable. See C<PL_DBsingle>. |
cb1a09d0 |
1655 | The sub name can be found by |
1656 | |
2d8e6c8d |
1657 | SvPV( GvSV( PL_DBsub ), len ) |
cb1a09d0 |
1658 | |
9cde0e7f |
1659 | =item PL_DBtrace |
5fb8527f |
1660 | |
1661 | Trace variable used when Perl is run in debugging mode, with the B<-d> |
1662 | switch. This is the C variable which corresponds to Perl's $DB::trace |
9cde0e7f |
1663 | variable. See C<PL_DBsingle>. |
5fb8527f |
1664 | |
cb1a09d0 |
1665 | =item dMARK |
1666 | |
5fb8527f |
1667 | Declare a stack marker variable, C<mark>, for the XSUB. See C<MARK> and |
1668 | C<dORIGMARK>. |
cb1a09d0 |
1669 | |
1670 | =item dORIGMARK |
1671 | |
1672 | Saves the original stack mark for the XSUB. See C<ORIGMARK>. |
1673 | |
9cde0e7f |
1674 | =item PL_dowarn |
5fb8527f |
1675 | |
1676 | The C variable which corresponds to Perl's $^W warning variable. |
1677 | |
cb1a09d0 |
1678 | =item dSP |
1679 | |
924508f0 |
1680 | Declares a local copy of perl's stack pointer for the XSUB, available via |
1681 | the C<SP> macro. See C<SP>. |
cb1a09d0 |
1682 | |
1683 | =item dXSARGS |
1684 | |
1685 | Sets up stack and mark pointers for an XSUB, calling dSP and dMARK. This is |
1686 | usually handled automatically by C<xsubpp>. Declares the C<items> variable |
1687 | to indicate the number of items on the stack. |
1688 | |
5fb8527f |
1689 | =item dXSI32 |
1690 | |
1691 | Sets up the C<ix> variable for an XSUB which has aliases. This is usually |
1692 | handled automatically by C<xsubpp>. |
1693 | |
491527d0 |
1694 | =item do_binmode |
1695 | |
1696 | Switches filehandle to binmode. C<iotype> is what C<IoTYPE(io)> would |
1697 | contain. |
1698 | |
1699 | do_binmode(fp, iotype, TRUE); |
1700 | |
cb1a09d0 |
1701 | =item ENTER |
1702 | |
1703 | Opening bracket on a callback. See C<LEAVE> and L<perlcall>. |
1704 | |
1705 | ENTER; |
1706 | |
1707 | =item EXTEND |
1708 | |
1709 | Used to extend the argument stack for an XSUB's return values. |
1710 | |
ef50df4b |
1711 | EXTEND( sp, int x ) |
cb1a09d0 |
1712 | |
e89caa19 |
1713 | =item fbm_compile |
1714 | |
1715 | Analyses the string in order to make fast searches on it using fbm_instr() -- |
1716 | the Boyer-Moore algorithm. |
1717 | |
411d5715 |
1718 | void fbm_compile(SV* sv, U32 flags) |
e89caa19 |
1719 | |
1720 | =item fbm_instr |
1721 | |
1722 | Returns the location of the SV in the string delimited by C<str> and |
1723 | C<strend>. It returns C<Nullch> if the string can't be found. The |
1724 | C<sv> does not have to be fbm_compiled, but the search will not be as |
1725 | fast then. |
1726 | |
411d5715 |
1727 | char* fbm_instr(char *str, char *strend, SV *sv, U32 flags) |
e89caa19 |
1728 | |
cb1a09d0 |
1729 | =item FREETMPS |
1730 | |
1731 | Closing bracket for temporaries on a callback. See C<SAVETMPS> and |
1732 | L<perlcall>. |
1733 | |
1734 | FREETMPS; |
1735 | |
1736 | =item G_ARRAY |
1737 | |
54310121 |
1738 | Used to indicate array context. See C<GIMME_V>, C<GIMME> and L<perlcall>. |
cb1a09d0 |
1739 | |
1740 | =item G_DISCARD |
1741 | |
1742 | Indicates that arguments returned from a callback should be discarded. See |
1743 | L<perlcall>. |
1744 | |
1745 | =item G_EVAL |
1746 | |
1747 | Used to force a Perl C<eval> wrapper around a callback. See L<perlcall>. |
1748 | |
1749 | =item GIMME |
1750 | |
54310121 |
1751 | A backward-compatible version of C<GIMME_V> which can only return |
1752 | C<G_SCALAR> or C<G_ARRAY>; in a void context, it returns C<G_SCALAR>. |
1753 | |
1754 | =item GIMME_V |
1755 | |
1756 | The XSUB-writer's equivalent to Perl's C<wantarray>. Returns |
1757 | C<G_VOID>, C<G_SCALAR> or C<G_ARRAY> for void, scalar or array |
1758 | context, respectively. |
cb1a09d0 |
1759 | |
1760 | =item G_NOARGS |
1761 | |
1762 | Indicates that no arguments are being sent to a callback. See L<perlcall>. |
1763 | |
1764 | =item G_SCALAR |
1765 | |
54310121 |
1766 | Used to indicate scalar context. See C<GIMME_V>, C<GIMME>, and L<perlcall>. |
1767 | |
faed5253 |
1768 | =item gv_fetchmeth |
1769 | |
1770 | Returns the glob with the given C<name> and a defined subroutine or |
9607fc9c |
1771 | C<NULL>. The glob lives in the given C<stash>, or in the stashes |
f86cebdf |
1772 | accessible via @ISA and @UNIVERSAL. |
faed5253 |
1773 | |
9607fc9c |
1774 | The argument C<level> should be either 0 or -1. If C<level==0>, as a |
0a753a76 |
1775 | side-effect creates a glob with the given C<name> in the given |
1776 | C<stash> which in the case of success contains an alias for the |
1777 | subroutine, and sets up caching info for this glob. Similarly for all |
1778 | the searched stashes. |
1779 | |
9607fc9c |
1780 | This function grants C<"SUPER"> token as a postfix of the stash name. |
1781 | |
0a753a76 |
1782 | The GV returned from C<gv_fetchmeth> may be a method cache entry, |
1783 | which is not visible to Perl code. So when calling C<perl_call_sv>, |
1784 | you should not use the GV directly; instead, you should use the |
1785 | method's CV, which can be obtained from the GV with the C<GvCV> macro. |
faed5253 |
1786 | |
ef50df4b |
1787 | GV* gv_fetchmeth (HV* stash, char* name, STRLEN len, I32 level) |
faed5253 |
1788 | |
1789 | =item gv_fetchmethod |
1790 | |
dc848c6f |
1791 | =item gv_fetchmethod_autoload |
1792 | |
faed5253 |
1793 | Returns the glob which contains the subroutine to call to invoke the |
dc848c6f |
1794 | method on the C<stash>. In fact in the presense of autoloading this may |
1795 | be the glob for "AUTOLOAD". In this case the corresponding variable |
faed5253 |
1796 | $AUTOLOAD is already setup. |
1797 | |
dc848c6f |
1798 | The third parameter of C<gv_fetchmethod_autoload> determines whether AUTOLOAD |
1799 | lookup is performed if the given method is not present: non-zero means |
1800 | yes, look for AUTOLOAD; zero means no, don't look for AUTOLOAD. Calling |
1801 | C<gv_fetchmethod> is equivalent to calling C<gv_fetchmethod_autoload> with a |
1802 | non-zero C<autoload> parameter. |
1803 | |
1804 | These functions grant C<"SUPER"> token as a prefix of the method name. |
1805 | |
1806 | Note that if you want to keep the returned glob for a long time, you |
1807 | need to check for it being "AUTOLOAD", since at the later time the call |
faed5253 |
1808 | may load a different subroutine due to $AUTOLOAD changing its value. |
1809 | Use the glob created via a side effect to do this. |
1810 | |
dc848c6f |
1811 | These functions have the same side-effects and as C<gv_fetchmeth> with |
1812 | C<level==0>. C<name> should be writable if contains C<':'> or C<'\''>. |
0a753a76 |
1813 | The warning against passing the GV returned by C<gv_fetchmeth> to |
dc848c6f |
1814 | C<perl_call_sv> apply equally to these functions. |
faed5253 |
1815 | |
ef50df4b |
1816 | GV* gv_fetchmethod (HV* stash, char* name) |
1817 | GV* gv_fetchmethod_autoload (HV* stash, char* name, I32 autoload) |
faed5253 |
1818 | |
e89caa19 |
1819 | =item G_VOID |
1820 | |
1821 | Used to indicate void context. See C<GIMME_V> and L<perlcall>. |
1822 | |
cb1a09d0 |
1823 | =item gv_stashpv |
1824 | |
1825 | Returns a pointer to the stash for a specified package. If C<create> is set |
1826 | then the package will be created if it does not already exist. If C<create> |
1827 | is not set and the package does not exist then NULL is returned. |
1828 | |
ef50df4b |
1829 | HV* gv_stashpv (char* name, I32 create) |
cb1a09d0 |
1830 | |
1831 | =item gv_stashsv |
1832 | |
1833 | Returns a pointer to the stash for a specified package. See C<gv_stashpv>. |
1834 | |
ef50df4b |
1835 | HV* gv_stashsv (SV* sv, I32 create) |
cb1a09d0 |
1836 | |
e5581bf4 |
1837 | =item GvSV |
cb1a09d0 |
1838 | |
e5581bf4 |
1839 | Return the SV from the GV. |
44a8e56a |
1840 | |
1e422769 |
1841 | =item HEf_SVKEY |
1842 | |
1843 | This flag, used in the length slot of hash entries and magic |
1844 | structures, specifies the structure contains a C<SV*> pointer where a |
1845 | C<char*> pointer is to be expected. (For information only--not to be used). |
1846 | |
1e422769 |
1847 | =item HeHASH |
1848 | |
e89caa19 |
1849 | Returns the computed hash stored in the hash entry. |
1e422769 |
1850 | |
e89caa19 |
1851 | U32 HeHASH(HE* he) |
1e422769 |
1852 | |
1853 | =item HeKEY |
1854 | |
1855 | Returns the actual pointer stored in the key slot of the hash entry. |
1856 | The pointer may be either C<char*> or C<SV*>, depending on the value of |
1857 | C<HeKLEN()>. Can be assigned to. The C<HePV()> or C<HeSVKEY()> macros |
1858 | are usually preferable for finding the value of a key. |
1859 | |
e89caa19 |
1860 | char* HeKEY(HE* he) |
1e422769 |
1861 | |
1862 | =item HeKLEN |
1863 | |
1864 | If this is negative, and amounts to C<HEf_SVKEY>, it indicates the entry |
1865 | holds an C<SV*> key. Otherwise, holds the actual length of the key. |
1866 | Can be assigned to. The C<HePV()> macro is usually preferable for finding |
1867 | key lengths. |
1868 | |
e89caa19 |
1869 | int HeKLEN(HE* he) |
1e422769 |
1870 | |
1871 | =item HePV |
1872 | |
1873 | Returns the key slot of the hash entry as a C<char*> value, doing any |
1874 | necessary dereferencing of possibly C<SV*> keys. The length of |
1875 | the string is placed in C<len> (this is a macro, so do I<not> use |
1876 | C<&len>). If you do not care about what the length of the key is, |
2d8e6c8d |
1877 | you may use the global variable C<PL_na>, though this is rather less |
1878 | efficient than using a local variable. Remember though, that hash |
1e422769 |
1879 | keys in perl are free to contain embedded nulls, so using C<strlen()> |
1880 | or similar is not a good way to find the length of hash keys. |
1881 | This is very similar to the C<SvPV()> macro described elsewhere in |
1882 | this document. |
1883 | |
e89caa19 |
1884 | char* HePV(HE* he, STRLEN len) |
1e422769 |
1885 | |
1886 | =item HeSVKEY |
1887 | |
1888 | Returns the key as an C<SV*>, or C<Nullsv> if the hash entry |
1889 | does not contain an C<SV*> key. |
1890 | |
1891 | HeSVKEY(HE* he) |
1892 | |
1893 | =item HeSVKEY_force |
1894 | |
1895 | Returns the key as an C<SV*>. Will create and return a temporary |
1896 | mortal C<SV*> if the hash entry contains only a C<char*> key. |
1897 | |
1898 | HeSVKEY_force(HE* he) |
1899 | |
1900 | =item HeSVKEY_set |
1901 | |
1902 | Sets the key to a given C<SV*>, taking care to set the appropriate flags |
1903 | to indicate the presence of an C<SV*> key, and returns the same C<SV*>. |
1904 | |
1905 | HeSVKEY_set(HE* he, SV* sv) |
1906 | |
1907 | =item HeVAL |
1908 | |
1909 | Returns the value slot (type C<SV*>) stored in the hash entry. |
1910 | |
1911 | HeVAL(HE* he) |
1912 | |
cb1a09d0 |
1913 | =item hv_clear |
1914 | |
1915 | Clears a hash, making it empty. |
1916 | |
ef50df4b |
1917 | void hv_clear (HV* tb) |
cb1a09d0 |
1918 | |
1919 | =item hv_delete |
1920 | |
1921 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
5fb8527f |
1922 | and returned to the caller. The C<klen> is the length of the key. The |
04343c6d |
1923 | C<flags> value will normally be zero; if set to G_DISCARD then NULL will be |
cb1a09d0 |
1924 | returned. |
1925 | |
ef50df4b |
1926 | SV* hv_delete (HV* tb, char* key, U32 klen, I32 flags) |
cb1a09d0 |
1927 | |
1e422769 |
1928 | =item hv_delete_ent |
1929 | |
1930 | Deletes a key/value pair in the hash. The value SV is removed from the hash |
1931 | and returned to the caller. The C<flags> value will normally be zero; if set |
04343c6d |
1932 | to G_DISCARD then NULL will be returned. C<hash> can be a valid precomputed |
1e422769 |
1933 | hash value, or 0 to ask for it to be computed. |
1934 | |
ef50df4b |
1935 | SV* hv_delete_ent (HV* tb, SV* key, I32 flags, U32 hash) |
1e422769 |
1936 | |
cb1a09d0 |
1937 | =item hv_exists |
1938 | |
1939 | Returns a boolean indicating whether the specified hash key exists. The |
5fb8527f |
1940 | C<klen> is the length of the key. |
cb1a09d0 |
1941 | |
ef50df4b |
1942 | bool hv_exists (HV* tb, char* key, U32 klen) |
cb1a09d0 |
1943 | |
1e422769 |
1944 | =item hv_exists_ent |
1945 | |
1946 | Returns a boolean indicating whether the specified hash key exists. C<hash> |
54310121 |
1947 | can be a valid precomputed hash value, or 0 to ask for it to be computed. |
1e422769 |
1948 | |
ef50df4b |
1949 | bool hv_exists_ent (HV* tb, SV* key, U32 hash) |
1e422769 |
1950 | |
cb1a09d0 |
1951 | =item hv_fetch |
1952 | |
1953 | Returns the SV which corresponds to the specified key in the hash. The |
5fb8527f |
1954 | C<klen> is the length of the key. If C<lval> is set then the fetch will be |
cb1a09d0 |
1955 | part of a store. Check that the return value is non-null before |
1956 | dereferencing it to a C<SV*>. |
1957 | |
04343c6d |
1958 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1959 | information on how to use this function on tied hashes. |
1960 | |
ef50df4b |
1961 | SV** hv_fetch (HV* tb, char* key, U32 klen, I32 lval) |
cb1a09d0 |
1962 | |
1e422769 |
1963 | =item hv_fetch_ent |
1964 | |
1965 | Returns the hash entry which corresponds to the specified key in the hash. |
54310121 |
1966 | C<hash> must be a valid precomputed hash number for the given C<key>, or |
1e422769 |
1967 | 0 if you want the function to compute it. IF C<lval> is set then the |
1968 | fetch will be part of a store. Make sure the return value is non-null |
1969 | before accessing it. The return value when C<tb> is a tied hash |
1970 | is a pointer to a static location, so be sure to make a copy of the |
1971 | structure if you need to store it somewhere. |
1972 | |
04343c6d |
1973 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
1974 | information on how to use this function on tied hashes. |
1975 | |
ef50df4b |
1976 | HE* hv_fetch_ent (HV* tb, SV* key, I32 lval, U32 hash) |
1e422769 |
1977 | |
cb1a09d0 |
1978 | =item hv_iterinit |
1979 | |
1980 | Prepares a starting point to traverse a hash table. |
1981 | |
ef50df4b |
1982 | I32 hv_iterinit (HV* tb) |
cb1a09d0 |
1983 | |
c6601927 |
1984 | Returns the number of keys in the hash (i.e. the same as C<HvKEYS(tb)>). |
1985 | The return value is currently only meaningful for hashes without tie |
1986 | magic. |
1987 | |
1988 | NOTE: Before version 5.004_65, C<hv_iterinit> used to return the number |
1989 | of hash buckets that happen to be in use. If you still need that |
1990 | esoteric value, you can get it through the macro C<HvFILL(tb)>. |
fb73857a |
1991 | |
cb1a09d0 |
1992 | =item hv_iterkey |
1993 | |
1994 | Returns the key from the current position of the hash iterator. See |
1995 | C<hv_iterinit>. |
1996 | |
ef50df4b |
1997 | char* hv_iterkey (HE* entry, I32* retlen) |
cb1a09d0 |
1998 | |
1e422769 |
1999 | =item hv_iterkeysv |
3fe9a6f1 |
2000 | |
1e422769 |
2001 | Returns the key as an C<SV*> from the current position of the hash |
2002 | iterator. The return value will always be a mortal copy of the |
2003 | key. Also see C<hv_iterinit>. |
2004 | |
ef50df4b |
2005 | SV* hv_iterkeysv (HE* entry) |
1e422769 |
2006 | |
cb1a09d0 |
2007 | =item hv_iternext |
2008 | |
2009 | Returns entries from a hash iterator. See C<hv_iterinit>. |
2010 | |
ef50df4b |
2011 | HE* hv_iternext (HV* tb) |
cb1a09d0 |
2012 | |
2013 | =item hv_iternextsv |
2014 | |
2015 | Performs an C<hv_iternext>, C<hv_iterkey>, and C<hv_iterval> in one |
2016 | operation. |
2017 | |
e89caa19 |
2018 | SV* hv_iternextsv (HV* hv, char** key, I32* retlen) |
cb1a09d0 |
2019 | |
2020 | =item hv_iterval |
2021 | |
2022 | Returns the value from the current position of the hash iterator. See |
2023 | C<hv_iterkey>. |
2024 | |
ef50df4b |
2025 | SV* hv_iterval (HV* tb, HE* entry) |
cb1a09d0 |
2026 | |
2027 | =item hv_magic |
2028 | |
2029 | Adds magic to a hash. See C<sv_magic>. |
2030 | |
ef50df4b |
2031 | void hv_magic (HV* hv, GV* gv, int how) |
cb1a09d0 |
2032 | |
2033 | =item HvNAME |
2034 | |
2035 | Returns the package name of a stash. See C<SvSTASH>, C<CvSTASH>. |
2036 | |
e89caa19 |
2037 | char* HvNAME (HV* stash) |
cb1a09d0 |
2038 | |
2039 | =item hv_store |
2040 | |
2041 | Stores an SV in a hash. The hash key is specified as C<key> and C<klen> is |
54310121 |
2042 | the length of the key. The C<hash> parameter is the precomputed hash |
cb1a09d0 |
2043 | value; if it is zero then Perl will compute it. The return value will be |
04343c6d |
2044 | NULL if the operation failed or if the value did not need to be actually |
2045 | stored within the hash (as in the case of tied hashes). Otherwise it can |
2046 | be dereferenced to get the original C<SV*>. Note that the caller is |
2047 | responsible for suitably incrementing the reference count of C<val> |
2048 | before the call, and decrementing it if the function returned NULL. |
2049 | |
2050 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
2051 | information on how to use this function on tied hashes. |
cb1a09d0 |
2052 | |
ef50df4b |
2053 | SV** hv_store (HV* tb, char* key, U32 klen, SV* val, U32 hash) |
cb1a09d0 |
2054 | |
1e422769 |
2055 | =item hv_store_ent |
2056 | |
2057 | Stores C<val> in a hash. The hash key is specified as C<key>. The C<hash> |
54310121 |
2058 | parameter is the precomputed hash value; if it is zero then Perl will |
1e422769 |
2059 | compute it. The return value is the new hash entry so created. It will be |
04343c6d |
2060 | NULL if the operation failed or if the value did not need to be actually |
2061 | stored within the hash (as in the case of tied hashes). Otherwise the |
2062 | contents of the return value can be accessed using the C<He???> macros |
2063 | described here. Note that the caller is responsible for suitably |
2064 | incrementing the reference count of C<val> before the call, and decrementing |
2065 | it if the function returned NULL. |
2066 | |
2067 | See L<Understanding the Magic of Tied Hashes and Arrays> for more |
2068 | information on how to use this function on tied hashes. |
1e422769 |
2069 | |
ef50df4b |
2070 | HE* hv_store_ent (HV* tb, SV* key, SV* val, U32 hash) |
1e422769 |
2071 | |
cb1a09d0 |
2072 | =item hv_undef |
2073 | |
2074 | Undefines the hash. |
2075 | |
ef50df4b |
2076 | void hv_undef (HV* tb) |
cb1a09d0 |
2077 | |
2078 | =item isALNUM |
2079 | |
2080 | Returns a boolean indicating whether the C C<char> is an ascii alphanumeric |
5f05dabc |
2081 | character or digit. |
cb1a09d0 |
2082 | |
e89caa19 |
2083 | int isALNUM (char c) |
cb1a09d0 |
2084 | |
2085 | =item isALPHA |
2086 | |
5fb8527f |
2087 | Returns a boolean indicating whether the C C<char> is an ascii alphabetic |
cb1a09d0 |
2088 | character. |
2089 | |
e89caa19 |
2090 | int isALPHA (char c) |
cb1a09d0 |
2091 | |
2092 | =item isDIGIT |
2093 | |
2094 | Returns a boolean indicating whether the C C<char> is an ascii digit. |
2095 | |
e89caa19 |
2096 | int isDIGIT (char c) |
cb1a09d0 |
2097 | |
2098 | =item isLOWER |
2099 | |
2100 | Returns a boolean indicating whether the C C<char> is a lowercase character. |
2101 | |
e89caa19 |
2102 | int isLOWER (char c) |
cb1a09d0 |
2103 | |
2104 | =item isSPACE |
2105 | |
2106 | Returns a boolean indicating whether the C C<char> is whitespace. |
2107 | |
e89caa19 |
2108 | int isSPACE (char c) |
cb1a09d0 |
2109 | |
2110 | =item isUPPER |
2111 | |
2112 | Returns a boolean indicating whether the C C<char> is an uppercase character. |
2113 | |
e89caa19 |
2114 | int isUPPER (char c) |
cb1a09d0 |
2115 | |
2116 | =item items |
2117 | |
2118 | Variable which is setup by C<xsubpp> to indicate the number of items on the |
5fb8527f |
2119 | stack. See L<perlxs/"Variable-length Parameter Lists">. |
2120 | |
2121 | =item ix |
2122 | |
2123 | Variable which is setup by C<xsubpp> to indicate which of an XSUB's aliases |
2124 | was used to invoke it. See L<perlxs/"The ALIAS: Keyword">. |
cb1a09d0 |
2125 | |
2126 | =item LEAVE |
2127 | |
2128 | Closing bracket on a callback. See C<ENTER> and L<perlcall>. |
2129 | |
2130 | LEAVE; |
2131 | |
e89caa19 |
2132 | =item looks_like_number |
2133 | |
2134 | Test if an the content of an SV looks like a number (or is a number). |
2135 | |
2136 | int looks_like_number(SV*) |
2137 | |
2138 | |
cb1a09d0 |
2139 | =item MARK |
2140 | |
5fb8527f |
2141 | Stack marker variable for the XSUB. See C<dMARK>. |
cb1a09d0 |
2142 | |
2143 | =item mg_clear |
2144 | |
2145 | Clear something magical that the SV represents. See C<sv_magic>. |
2146 | |
ef50df4b |
2147 | int mg_clear (SV* sv) |
cb1a09d0 |
2148 | |
2149 | =item mg_copy |
2150 | |
2151 | Copies the magic from one SV to another. See C<sv_magic>. |
2152 | |
ef50df4b |
2153 | int mg_copy (SV *, SV *, char *, STRLEN) |
cb1a09d0 |
2154 | |
2155 | =item mg_find |
2156 | |
2157 | Finds the magic pointer for type matching the SV. See C<sv_magic>. |
2158 | |
ef50df4b |
2159 | MAGIC* mg_find (SV* sv, int type) |
cb1a09d0 |
2160 | |
2161 | =item mg_free |
2162 | |
2163 | Free any magic storage used by the SV. See C<sv_magic>. |
2164 | |
ef50df4b |
2165 | int mg_free (SV* sv) |
cb1a09d0 |
2166 | |
2167 | =item mg_get |
2168 | |
2169 | Do magic after a value is retrieved from the SV. See C<sv_magic>. |
2170 | |
ef50df4b |
2171 | int mg_get (SV* sv) |
cb1a09d0 |
2172 | |
2173 | =item mg_len |
2174 | |
2175 | Report on the SV's length. See C<sv_magic>. |
2176 | |
ef50df4b |
2177 | U32 mg_len (SV* sv) |
cb1a09d0 |
2178 | |
2179 | =item mg_magical |
2180 | |
2181 | Turns on the magical status of an SV. See C<sv_magic>. |
2182 | |
ef50df4b |
2183 | void mg_magical (SV* sv) |
cb1a09d0 |
2184 | |
2185 | =item mg_set |
2186 | |
2187 | Do magic after a value is assigned to the SV. See C<sv_magic>. |
2188 | |
ef50df4b |
2189 | int mg_set (SV* sv) |
cb1a09d0 |
2190 | |
b0fffe30 |
2191 | =item modglobal |
2192 | |
2193 | C<modglobal> is a general purpose, interpreter global HV for use by |
db696efe |
2194 | extensions that need to keep information on a per-interpreter basis. |
2195 | In a pinch, it can also be used as a symbol table for extensions |
2196 | to share data among each other. It is a good idea to use keys |
2197 | prefixed by the package name of the extension that owns the data. |
b0fffe30 |
2198 | |
cb1a09d0 |
2199 | =item Move |
2200 | |
2201 | The XSUB-writer's interface to the C C<memmove> function. The C<s> is the |
2202 | source, C<d> is the destination, C<n> is the number of items, and C<t> is |
0146554f |
2203 | the type. Can do overlapping moves. See also C<Copy>. |
cb1a09d0 |
2204 | |
e89caa19 |
2205 | void Move( s, d, n, t ) |
cb1a09d0 |
2206 | |
9cde0e7f |
2207 | =item PL_na |
cb1a09d0 |
2208 | |
2d8e6c8d |
2209 | A convenience variable which is typically used with C<SvPV> when one doesn't |
2210 | care about the length of the string. It is usually more efficient to |
1fa8b10d |
2211 | either declare a local variable and use that instead or to use the C<SvPV_nolen> |
2212 | macro. |
cb1a09d0 |
2213 | |
2214 | =item New |
2215 | |
2216 | The XSUB-writer's interface to the C C<malloc> function. |
2217 | |
e89caa19 |
2218 | void* New( x, void *ptr, int size, type ) |
cb1a09d0 |
2219 | |
2220 | =item newAV |
2221 | |
5f05dabc |
2222 | Creates a new AV. The reference count is set to 1. |
cb1a09d0 |
2223 | |
ef50df4b |
2224 | AV* newAV (void) |
cb1a09d0 |
2225 | |
e89caa19 |
2226 | =item Newc |
2227 | |
2228 | The XSUB-writer's interface to the C C<malloc> function, with cast. |
2229 | |
2230 | void* Newc( x, void *ptr, int size, type, cast ) |
2231 | |
5476c433 |
2232 | =item newCONSTSUB |
2233 | |
2234 | Creates a constant sub equivalent to Perl C<sub FOO () { 123 }> |
2235 | which is eligible for inlining at compile-time. |
2236 | |
2237 | void newCONSTSUB(HV* stash, char* name, SV* sv) |
2238 | |
cb1a09d0 |
2239 | =item newHV |
2240 | |
5f05dabc |
2241 | Creates a new HV. The reference count is set to 1. |
cb1a09d0 |
2242 | |
ef50df4b |
2243 | HV* newHV (void) |
cb1a09d0 |
2244 | |
5f05dabc |
2245 | =item newRV_inc |
cb1a09d0 |
2246 | |
5f05dabc |
2247 | Creates an RV wrapper for an SV. The reference count for the original SV is |
cb1a09d0 |
2248 | incremented. |
2249 | |
ef50df4b |
2250 | SV* newRV_inc (SV* ref) |
5f05dabc |
2251 | |
2252 | For historical reasons, "newRV" is a synonym for "newRV_inc". |
2253 | |
2254 | =item newRV_noinc |
2255 | |
2256 | Creates an RV wrapper for an SV. The reference count for the original |
2257 | SV is B<not> incremented. |
2258 | |
ef50df4b |
2259 | SV* newRV_noinc (SV* ref) |
cb1a09d0 |
2260 | |
8c52afec |
2261 | =item NEWSV |
cb1a09d0 |
2262 | |
e89caa19 |
2263 | Creates a new SV. A non-zero C<len> parameter indicates the number of |
2264 | bytes of preallocated string space the SV should have. An extra byte |
2265 | for a tailing NUL is also reserved. (SvPOK is not set for the SV even |
2266 | if string space is allocated.) The reference count for the new SV is |
2267 | set to 1. C<id> is an integer id between 0 and 1299 (used to identify |
2268 | leaks). |
cb1a09d0 |
2269 | |
ef50df4b |
2270 | SV* NEWSV (int id, STRLEN len) |
cb1a09d0 |
2271 | |
2272 | =item newSViv |
2273 | |
07fa94a1 |
2274 | Creates a new SV and copies an integer into it. The reference count for the |
2275 | SV is set to 1. |
cb1a09d0 |
2276 | |
ef50df4b |
2277 | SV* newSViv (IV i) |
cb1a09d0 |
2278 | |
2279 | =item newSVnv |
2280 | |
07fa94a1 |
2281 | Creates a new SV and copies a double into it. The reference count for the |
2282 | SV is set to 1. |
cb1a09d0 |
2283 | |
ef50df4b |
2284 | SV* newSVnv (NV i) |
cb1a09d0 |
2285 | |
2286 | =item newSVpv |
2287 | |
07fa94a1 |
2288 | Creates a new SV and copies a string into it. The reference count for the |
2289 | SV is set to 1. If C<len> is zero then Perl will compute the length. |
cb1a09d0 |
2290 | |
ef50df4b |
2291 | SV* newSVpv (char* s, STRLEN len) |
cb1a09d0 |
2292 | |
e89caa19 |
2293 | =item newSVpvf |
2294 | |
2295 | Creates a new SV an initialize it with the string formatted like |
2296 | C<sprintf>. |
2297 | |
2298 | SV* newSVpvf(const char* pat, ...); |
2299 | |
9da1e3b5 |
2300 | =item newSVpvn |
2301 | |
2302 | Creates a new SV and copies a string into it. The reference count for the |
2303 | SV is set to 1. If C<len> is zero then Perl will create a zero length |
2304 | string. |
2305 | |
ef50df4b |
2306 | SV* newSVpvn (char* s, STRLEN len) |
9da1e3b5 |
2307 | |
cb1a09d0 |
2308 | =item newSVrv |
2309 | |
2310 | Creates a new SV for the RV, C<rv>, to point to. If C<rv> is not an RV then |
5fb8527f |
2311 | it will be upgraded to one. If C<classname> is non-null then the new SV will |
cb1a09d0 |
2312 | be blessed in the specified package. The new SV is returned and its |
5f05dabc |
2313 | reference count is 1. |
8ebc5c01 |
2314 | |
ef50df4b |
2315 | SV* newSVrv (SV* rv, char* classname) |
cb1a09d0 |
2316 | |
2317 | =item newSVsv |
2318 | |
5fb8527f |
2319 | Creates a new SV which is an exact duplicate of the original SV. |
cb1a09d0 |
2320 | |
ef50df4b |
2321 | SV* newSVsv (SV* old) |
cb1a09d0 |
2322 | |
2323 | =item newXS |
2324 | |
2325 | Used by C<xsubpp> to hook up XSUBs as Perl subs. |
2326 | |
2327 | =item newXSproto |
2328 | |
2329 | Used by C<xsubpp> to hook up XSUBs as Perl subs. Adds Perl prototypes to |
2330 | the subs. |
2331 | |
e89caa19 |
2332 | =item Newz |
2333 | |
2334 | The XSUB-writer's interface to the C C<malloc> function. The allocated |
2335 | memory is zeroed with C<memzero>. |
2336 | |
2337 | void* Newz( x, void *ptr, int size, type ) |
2338 | |
cb1a09d0 |
2339 | =item Nullav |
2340 | |
2341 | Null AV pointer. |
2342 | |
2343 | =item Nullch |
2344 | |
2345 | Null character pointer. |
2346 | |
2347 | =item Nullcv |
2348 | |
2349 | Null CV pointer. |
2350 | |
2351 | =item Nullhv |
2352 | |
2353 | Null HV pointer. |
2354 | |
2355 | =item Nullsv |
2356 | |
2357 | Null SV pointer. |
2358 | |
2359 | =item ORIGMARK |
2360 | |
2361 | The original stack mark for the XSUB. See C<dORIGMARK>. |
2362 | |
2363 | =item perl_alloc |
2364 | |
2365 | Allocates a new Perl interpreter. See L<perlembed>. |
2366 | |
2367 | =item perl_call_argv |
2368 | |
2369 | Performs a callback to the specified Perl sub. See L<perlcall>. |
2370 | |
ef50df4b |
2371 | I32 perl_call_argv (char* subname, I32 flags, char** argv) |
cb1a09d0 |
2372 | |
2373 | =item perl_call_method |
2374 | |
2375 | Performs a callback to the specified Perl method. The blessed object must |
2376 | be on the stack. See L<perlcall>. |
2377 | |
ef50df4b |
2378 | I32 perl_call_method (char* methname, I32 flags) |
cb1a09d0 |
2379 | |
2380 | =item perl_call_pv |
2381 | |
2382 | Performs a callback to the specified Perl sub. See L<perlcall>. |
2383 | |
ef50df4b |
2384 | I32 perl_call_pv (char* subname, I32 flags) |
cb1a09d0 |
2385 | |
2386 | =item perl_call_sv |
2387 | |
2388 | Performs a callback to the Perl sub whose name is in the SV. See |
2389 | L<perlcall>. |
2390 | |
ef50df4b |
2391 | I32 perl_call_sv (SV* sv, I32 flags) |
cb1a09d0 |
2392 | |
2393 | =item perl_construct |
2394 | |
2395 | Initializes a new Perl interpreter. See L<perlembed>. |
2396 | |
2397 | =item perl_destruct |
2398 | |
2399 | Shuts down a Perl interpreter. See L<perlembed>. |
2400 | |
2401 | =item perl_eval_sv |
2402 | |
2403 | Tells Perl to C<eval> the string in the SV. |
2404 | |
ef50df4b |
2405 | I32 perl_eval_sv (SV* sv, I32 flags) |
cb1a09d0 |
2406 | |
137443ea |
2407 | =item perl_eval_pv |
2408 | |
2409 | Tells Perl to C<eval> the given string and return an SV* result. |
2410 | |
ef50df4b |
2411 | SV* perl_eval_pv (char* p, I32 croak_on_error) |
137443ea |
2412 | |
cb1a09d0 |
2413 | =item perl_free |
2414 | |
2415 | Releases a Perl interpreter. See L<perlembed>. |
2416 | |
2417 | =item perl_get_av |
2418 | |
2419 | Returns the AV of the specified Perl array. If C<create> is set and the |
2420 | Perl variable does not exist then it will be created. If C<create> is not |
04343c6d |
2421 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2422 | |
ef50df4b |
2423 | AV* perl_get_av (char* name, I32 create) |
cb1a09d0 |
2424 | |
2425 | =item perl_get_cv |
2426 | |
2427 | Returns the CV of the specified Perl sub. If C<create> is set and the Perl |
2428 | variable does not exist then it will be created. If C<create> is not |
04343c6d |
2429 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2430 | |
ef50df4b |
2431 | CV* perl_get_cv (char* name, I32 create) |
cb1a09d0 |
2432 | |
2433 | =item perl_get_hv |
2434 | |
2435 | Returns the HV of the specified Perl hash. If C<create> is set and the Perl |
2436 | variable does not exist then it will be created. If C<create> is not |
04343c6d |
2437 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2438 | |
ef50df4b |
2439 | HV* perl_get_hv (char* name, I32 create) |
cb1a09d0 |
2440 | |
2441 | =item perl_get_sv |
2442 | |
2443 | Returns the SV of the specified Perl scalar. If C<create> is set and the |
2444 | Perl variable does not exist then it will be created. If C<create> is not |
04343c6d |
2445 | set and the variable does not exist then NULL is returned. |
cb1a09d0 |
2446 | |
ef50df4b |
2447 | SV* perl_get_sv (char* name, I32 create) |
cb1a09d0 |
2448 | |
2449 | =item perl_parse |
2450 | |
2451 | Tells a Perl interpreter to parse a Perl script. See L<perlembed>. |
2452 | |
2453 | =item perl_require_pv |
2454 | |
2455 | Tells Perl to C<require> a module. |
2456 | |
ef50df4b |
2457 | void perl_require_pv (char* pv) |
cb1a09d0 |
2458 | |
2459 | =item perl_run |
2460 | |
2461 | Tells a Perl interpreter to run. See L<perlembed>. |
2462 | |
2463 | =item POPi |
2464 | |
2465 | Pops an integer off the stack. |
2466 | |
e89caa19 |
2467 | int POPi() |
cb1a09d0 |
2468 | |
2469 | =item POPl |
2470 | |
2471 | Pops a long off the stack. |
2472 | |
e89caa19 |
2473 | long POPl() |
cb1a09d0 |
2474 | |
2475 | =item POPp |
2476 | |
2477 | Pops a string off the stack. |
2478 | |
e89caa19 |
2479 | char* POPp() |
cb1a09d0 |
2480 | |
2481 | =item POPn |
2482 | |
2483 | Pops a double off the stack. |
2484 | |
e89caa19 |
2485 | double POPn() |
cb1a09d0 |
2486 | |
2487 | =item POPs |
2488 | |
2489 | Pops an SV off the stack. |
2490 | |
e89caa19 |
2491 | SV* POPs() |
cb1a09d0 |
2492 | |
2493 | =item PUSHMARK |
2494 | |
2495 | Opening bracket for arguments on a callback. See C<PUTBACK> and L<perlcall>. |
2496 | |
2497 | PUSHMARK(p) |
2498 | |
2499 | =item PUSHi |
2500 | |
2501 | Push an integer onto the stack. The stack must have room for this element. |
189b2af5 |
2502 | Handles 'set' magic. See C<XPUSHi>. |
cb1a09d0 |
2503 | |
e89caa19 |
2504 | void PUSHi(int d) |
cb1a09d0 |
2505 | |
2506 | =item PUSHn |
2507 | |
2508 | Push a double onto the stack. The stack must have room for this element. |
189b2af5 |
2509 | Handles 'set' magic. See C<XPUSHn>. |
cb1a09d0 |
2510 | |
e89caa19 |
2511 | void PUSHn(double d) |
cb1a09d0 |
2512 | |
2513 | =item PUSHp |
2514 | |
2515 | Push a string onto the stack. The stack must have room for this element. |
189b2af5 |
2516 | The C<len> indicates the length of the string. Handles 'set' magic. See |
2517 | C<XPUSHp>. |
cb1a09d0 |
2518 | |
e89caa19 |
2519 | void PUSHp(char *c, int len ) |
cb1a09d0 |
2520 | |
2521 | =item PUSHs |
2522 | |
189b2af5 |
2523 | Push an SV onto the stack. The stack must have room for this element. Does |
2524 | not handle 'set' magic. See C<XPUSHs>. |
cb1a09d0 |
2525 | |
e89caa19 |
2526 | void PUSHs(sv) |
2527 | |
2528 | =item PUSHu |
2529 | |
2530 | Push an unsigned integer onto the stack. The stack must have room for |
2531 | this element. See C<XPUSHu>. |
2532 | |
2533 | void PUSHu(unsigned int d) |
2534 | |
cb1a09d0 |
2535 | |
2536 | =item PUTBACK |
2537 | |
2538 | Closing bracket for XSUB arguments. This is usually handled by C<xsubpp>. |
2539 | See C<PUSHMARK> and L<perlcall> for other uses. |
2540 | |
2541 | PUTBACK; |
2542 | |
2543 | =item Renew |
2544 | |
2545 | The XSUB-writer's interface to the C C<realloc> function. |
2546 | |
e89caa19 |
2547 | void* Renew( void *ptr, int size, type ) |
cb1a09d0 |
2548 | |
2549 | =item Renewc |
2550 | |
2551 | The XSUB-writer's interface to the C C<realloc> function, with cast. |
2552 | |
e89caa19 |
2553 | void* Renewc( void *ptr, int size, type, cast ) |
cb1a09d0 |
2554 | |
2555 | =item RETVAL |
2556 | |
2557 | Variable which is setup by C<xsubpp> to hold the return value for an XSUB. |
5fb8527f |
2558 | This is always the proper type for the XSUB. |
2559 | See L<perlxs/"The RETVAL Variable">. |
cb1a09d0 |
2560 | |
2561 | =item safefree |
2562 | |
2563 | The XSUB-writer's interface to the C C<free> function. |
2564 | |
2565 | =item safemalloc |
2566 | |
2567 | The XSUB-writer's interface to the C C<malloc> function. |
2568 | |
2569 | =item saferealloc |
2570 | |
2571 | The XSUB-writer's interface to the C C<realloc> function. |
2572 | |
2573 | =item savepv |
2574 | |
2575 | Copy a string to a safe spot. This does not use an SV. |
2576 | |
ef50df4b |
2577 | char* savepv (char* sv) |
cb1a09d0 |
2578 | |
2579 | =item savepvn |
2580 | |
2581 | Copy a string to a safe spot. The C<len> indicates number of bytes to |
2582 | copy. This does not use an SV. |
2583 | |
ef50df4b |
2584 | char* savepvn (char* sv, I32 len) |
cb1a09d0 |
2585 | |
2586 | =item SAVETMPS |
2587 | |
2588 | Opening bracket for temporaries on a callback. See C<FREETMPS> and |
2589 | L<perlcall>. |
2590 | |
2591 | SAVETMPS; |
2592 | |
2593 | =item SP |
2594 | |
2595 | Stack pointer. This is usually handled by C<xsubpp>. See C<dSP> and |
2596 | C<SPAGAIN>. |
2597 | |
2598 | =item SPAGAIN |
2599 | |
54310121 |
2600 | Refetch the stack pointer. Used after a callback. See L<perlcall>. |
cb1a09d0 |
2601 | |
2602 | SPAGAIN; |
2603 | |
2604 | =item ST |
2605 | |
2606 | Used to access elements on the XSUB's stack. |
2607 | |
e89caa19 |
2608 | SV* ST(int x) |
cb1a09d0 |
2609 | |
2610 | =item strEQ |
2611 | |
2612 | Test two strings to see if they are equal. Returns true or false. |
2613 | |
e89caa19 |
2614 | int strEQ( char *s1, char *s2 ) |
cb1a09d0 |
2615 | |
2616 | =item strGE |
2617 | |
2618 | Test two strings to see if the first, C<s1>, is greater than or equal to the |
2619 | second, C<s2>. Returns true or false. |
2620 | |
e89caa19 |
2621 | int strGE( char *s1, char *s2 ) |
cb1a09d0 |
2622 | |
2623 | =item strGT |
2624 | |
2625 | Test two strings to see if the first, C<s1>, is greater than the second, |
2626 | C<s2>. Returns true or false. |
2627 | |
e89caa19 |
2628 | int strGT( char *s1, char *s2 ) |
cb1a09d0 |
2629 | |
2630 | =item strLE |
2631 | |
2632 | Test two strings to see if the first, C<s1>, is less than or equal to the |
2633 | second, C<s2>. Returns true or false. |
2634 | |
e89caa19 |
2635 | int strLE( char *s1, char *s2 ) |
cb1a09d0 |
2636 | |
2637 | =item strLT |
2638 | |
2639 | Test two strings to see if the first, C<s1>, is less than the second, |
2640 | C<s2>. Returns true or false. |
2641 | |
e89caa19 |
2642 | int strLT( char *s1, char *s2 ) |
cb1a09d0 |
2643 | |
2644 | =item strNE |
2645 | |
2646 | Test two strings to see if they are different. Returns true or false. |
2647 | |
e89caa19 |
2648 | int strNE( char *s1, char *s2 ) |
cb1a09d0 |
2649 | |
2650 | =item strnEQ |
2651 | |
2652 | Test two strings to see if they are equal. The C<len> parameter indicates |
2653 | the number of bytes to compare. Returns true or false. |
2654 | |
e89caa19 |
2655 | int strnEQ( char *s1, char *s2 ) |
cb1a09d0 |
2656 | |
2657 | =item strnNE |
2658 | |
2659 | Test two strings to see if they are different. The C<len> parameter |
2660 | indicates the number of bytes to compare. Returns true or false. |
2661 | |
e89caa19 |
2662 | int strnNE( char *s1, char *s2, int len ) |
cb1a09d0 |
2663 | |
2664 | =item sv_2mortal |
2665 | |
2666 | Marks an SV as mortal. The SV will be destroyed when the current context |
2667 | ends. |
2668 | |
ef50df4b |
2669 | SV* sv_2mortal (SV* sv) |
cb1a09d0 |
2670 | |
2671 | =item sv_bless |
2672 | |
2673 | Blesses an SV into a specified package. The SV must be an RV. The package |
07fa94a1 |
2674 | must be designated by its stash (see C<gv_stashpv()>). The reference count |
2675 | of the SV is unaffected. |
cb1a09d0 |
2676 | |
ef50df4b |
2677 | SV* sv_bless (SV* sv, HV* stash) |
cb1a09d0 |
2678 | |
ef50df4b |
2679 | =item sv_catpv |
189b2af5 |
2680 | |
ef50df4b |
2681 | Concatenates the string onto the end of the string which is in the SV. |
2682 | Handles 'get' magic, but not 'set' magic. See C<sv_catpv_mg>. |
189b2af5 |
2683 | |
ef50df4b |
2684 | void sv_catpv (SV* sv, char* ptr) |
189b2af5 |
2685 | |
ef50df4b |
2686 | =item sv_catpv_mg |
cb1a09d0 |
2687 | |
ef50df4b |
2688 | Like C<sv_catpv>, but also handles 'set' magic. |
cb1a09d0 |
2689 | |
ef50df4b |
2690 | void sv_catpvn (SV* sv, char* ptr) |
cb1a09d0 |
2691 | |
2692 | =item sv_catpvn |
2693 | |
2694 | Concatenates the string onto the end of the string which is in the SV. The |
189b2af5 |
2695 | C<len> indicates number of bytes to copy. Handles 'get' magic, but not |
ef50df4b |
2696 | 'set' magic. See C<sv_catpvn_mg>. |
cb1a09d0 |
2697 | |
ef50df4b |
2698 | void sv_catpvn (SV* sv, char* ptr, STRLEN len) |
2699 | |
2700 | =item sv_catpvn_mg |
2701 | |
2702 | Like C<sv_catpvn>, but also handles 'set' magic. |
2703 | |
2704 | void sv_catpvn_mg (SV* sv, char* ptr, STRLEN len) |
cb1a09d0 |
2705 | |
46fc3d4c |
2706 | =item sv_catpvf |
2707 | |
2708 | Processes its arguments like C<sprintf> and appends the formatted output |
189b2af5 |
2709 | to an SV. Handles 'get' magic, but not 'set' magic. C<SvSETMAGIC()> must |
2710 | typically be called after calling this function to handle 'set' magic. |
46fc3d4c |
2711 | |
ef50df4b |
2712 | void sv_catpvf (SV* sv, const char* pat, ...) |
2713 | |
2714 | =item sv_catpvf_mg |
2715 | |
2716 | Like C<sv_catpvf>, but also handles 'set' magic. |
2717 | |
2718 | void sv_catpvf_mg (SV* sv, const char* pat, ...) |
46fc3d4c |
2719 | |
cb1a09d0 |
2720 | =item sv_catsv |
2721 | |
5fb8527f |
2722 | Concatenates the string from SV C<ssv> onto the end of the string in SV |
ef50df4b |
2723 | C<dsv>. Handles 'get' magic, but not 'set' magic. See C<sv_catsv_mg>. |
2724 | |
2725 | void sv_catsv (SV* dsv, SV* ssv) |
2726 | |
2727 | =item sv_catsv_mg |
cb1a09d0 |
2728 | |
ef50df4b |
2729 | Like C<sv_catsv>, but also handles 'set' magic. |
2730 | |
2731 | void sv_catsv_mg (SV* dsv, SV* ssv) |
cb1a09d0 |
2732 | |
e89caa19 |
2733 | =item sv_chop |
2734 | |
2735 | Efficient removal of characters from the beginning of the string |
2736 | buffer. SvPOK(sv) must be true and the C<ptr> must be a pointer to |
2737 | somewhere inside the string buffer. The C<ptr> becomes the first |
2738 | character of the adjusted string. |
2739 | |
2740 | void sv_chop(SV* sv, char *ptr) |
2741 | |
2742 | |
5fb8527f |
2743 | =item sv_cmp |
2744 | |
2745 | Compares the strings in two SVs. Returns -1, 0, or 1 indicating whether the |
2746 | string in C<sv1> is less than, equal to, or greater than the string in |
2747 | C<sv2>. |
2748 | |
ef50df4b |
2749 | I32 sv_cmp (SV* sv1, SV* sv2) |
5fb8527f |
2750 | |
cb1a09d0 |
2751 | =item SvCUR |
2752 | |
2753 | Returns the length of the string which is in the SV. See C<SvLEN>. |
2754 | |
e89caa19 |
2755 | int SvCUR (SV* sv) |
cb1a09d0 |
2756 | |
2757 | =item SvCUR_set |
2758 | |
2759 | Set the length of the string which is in the SV. See C<SvCUR>. |
2760 | |
e89caa19 |
2761 | void SvCUR_set (SV* sv, int val ) |
cb1a09d0 |
2762 | |
5fb8527f |
2763 | =item sv_dec |
2764 | |
5f05dabc |
2765 | Auto-decrement of the value in the SV. |
5fb8527f |
2766 | |
ef50df4b |
2767 | void sv_dec (SV* sv) |
5fb8527f |
2768 | |
e89caa19 |
2769 | =item sv_derived_from |
2770 | |
2771 | Returns a boolean indicating whether the SV is a subclass of the |
2772 | specified class. |
2773 | |
2774 | int sv_derived_from(SV* sv, char* class) |
2775 | |
9abd00ed |
2776 | =item sv_derived_from |
2777 | |
2778 | Returns a boolean indicating whether the SV is derived from the specified |
2779 | class. This is the function that implements C<UNIVERSAL::isa>. It works |
2780 | for class names as well as for objects. |
2781 | |
2782 | bool sv_derived_from _((SV* sv, char* name)); |
2783 | |
cb1a09d0 |
2784 | =item SvEND |
2785 | |
2786 | Returns a pointer to the last character in the string which is in the SV. |
2787 | See C<SvCUR>. Access the character as |
2788 | |
e89caa19 |
2789 | char* SvEND(sv) |
cb1a09d0 |
2790 | |
5fb8527f |
2791 | =item sv_eq |
2792 | |
2793 | Returns a boolean indicating whether the strings in the two SVs are |
2794 | identical. |
2795 | |
ef50df4b |
2796 | I32 sv_eq (SV* sv1, SV* sv2) |
5fb8527f |
2797 | |
189b2af5 |
2798 | =item SvGETMAGIC |
2799 | |
2800 | Invokes C<mg_get> on an SV if it has 'get' magic. This macro evaluates |
2801 | its argument more than once. |
2802 | |
2803 | void SvGETMAGIC( SV *sv ) |
2804 | |
cb1a09d0 |
2805 | =item SvGROW |
2806 | |
e89caa19 |
2807 | Expands the character buffer in the SV so that it has room for the |
2808 | indicated number of bytes (remember to reserve space for an extra |
2809 | trailing NUL character). Calls C<sv_grow> to perform the expansion if |
2810 | necessary. Returns a pointer to the character buffer. |
cb1a09d0 |
2811 | |
22c35a8c |
2812 | char* SvGROW( SV* sv, STRLEN len ) |
cb1a09d0 |
2813 | |
5fb8527f |
2814 | =item sv_grow |
2815 | |
2816 | Expands the character buffer in the SV. This will use C<sv_unref> and will |
2817 | upgrade the SV to C<SVt_PV>. Returns a pointer to the character buffer. |
2818 | Use C<SvGROW>. |
2819 | |
2820 | =item sv_inc |
2821 | |
07fa94a1 |
2822 | Auto-increment of the value in the SV. |
5fb8527f |
2823 | |
ef50df4b |
2824 | void sv_inc (SV* sv) |
5fb8527f |
2825 | |
e89caa19 |
2826 | =item sv_insert |
2827 | |
2828 | Inserts a string at the specified offset/length within the SV. |
2829 | Similar to the Perl substr() function. |
2830 | |
2831 | void sv_insert(SV *sv, STRLEN offset, STRLEN len, |
2832 | char *str, STRLEN strlen) |
2833 | |
cb1a09d0 |
2834 | =item SvIOK |
2835 | |
2836 | Returns a boolean indicating whether the SV contains an integer. |
2837 | |
e89caa19 |
2838 | int SvIOK (SV* SV) |
cb1a09d0 |
2839 | |
2840 | =item SvIOK_off |
2841 | |
2842 | Unsets the IV status of an SV. |
2843 | |
e89caa19 |
2844 | void SvIOK_off (SV* sv) |
cb1a09d0 |
2845 | |
2846 | =item SvIOK_on |
2847 | |
2848 | Tells an SV that it is an integer. |
2849 | |
e89caa19 |
2850 | void SvIOK_on (SV* sv) |
cb1a09d0 |
2851 | |
5fb8527f |
2852 | =item SvIOK_only |
2853 | |
2854 | Tells an SV that it is an integer and disables all other OK bits. |
2855 | |
e89caa19 |
2856 | void SvIOK_only (SV* sv) |
5fb8527f |
2857 | |
cb1a09d0 |
2858 | =item SvIOKp |
2859 | |
2860 | Returns a boolean indicating whether the SV contains an integer. Checks the |
2861 | B<private> setting. Use C<SvIOK>. |
2862 | |
e89caa19 |
2863 | int SvIOKp (SV* SV) |
cb1a09d0 |
2864 | |
2865 | =item sv_isa |
2866 | |
2867 | Returns a boolean indicating whether the SV is blessed into the specified |
9abd00ed |
2868 | class. This does not check for subtypes; use C<sv_derived_from> to verify |
cb1a09d0 |
2869 | an inheritance relationship. |
2870 | |
ef50df4b |
2871 | int sv_isa (SV* sv, char* name) |
cb1a09d0 |
2872 | |
cb1a09d0 |
2873 | =item sv_isobject |
2874 | |
2875 | Returns a boolean indicating whether the SV is an RV pointing to a blessed |
2876 | object. If the SV is not an RV, or if the object is not blessed, then this |
2877 | will return false. |
2878 | |
ef50df4b |
2879 | int sv_isobject (SV* sv) |
cb1a09d0 |
2880 | |
e89caa19 |
2881 | =item SvIV |
2882 | |
5c68b227 |
2883 | Coerces the given SV to an integer and returns it. |
e89caa19 |
2884 | |
9abd00ed |
2885 | int SvIV (SV* sv) |
a59f3522 |
2886 | |
cb1a09d0 |
2887 | =item SvIVX |
2888 | |
5c68b227 |
2889 | Returns the integer which is stored in the SV, assuming SvIOK is true. |
cb1a09d0 |
2890 | |
e89caa19 |
2891 | int SvIVX (SV* sv) |
cb1a09d0 |
2892 | |
2893 | =item SvLEN |
2894 | |
2895 | Returns the size of the string buffer in the SV. See C<SvCUR>. |
2896 | |
e89caa19 |
2897 | int SvLEN (SV* sv) |
cb1a09d0 |
2898 | |
5fb8527f |
2899 | =item sv_len |
2900 | |
2901 | Returns the length of the string in the SV. Use C<SvCUR>. |
2902 | |
ef50df4b |
2903 | STRLEN sv_len (SV* sv) |
5fb8527f |
2904 | |
cb1a09d0 |
2905 | =item sv_magic |
2906 | |
2907 | Adds magic to an SV. |
2908 | |
ef50df4b |
2909 | void sv_magic (SV* sv, SV* obj, int how, char* name, I32 namlen) |
cb1a09d0 |
2910 | |
2911 | =item sv_mortalcopy |
2912 | |
2913 | Creates a new SV which is a copy of the original SV. The new SV is marked |
5f05dabc |
2914 | as mortal. |
cb1a09d0 |
2915 | |
ef50df4b |
2916 | SV* sv_mortalcopy (SV* oldsv) |
cb1a09d0 |
2917 | |
cb1a09d0 |
2918 | =item sv_newmortal |
2919 | |
5f05dabc |
2920 | Creates a new SV which is mortal. The reference count of the SV is set to 1. |
cb1a09d0 |
2921 | |
ef50df4b |
2922 | SV* sv_newmortal (void) |
cb1a09d0 |
2923 | |
cb1a09d0 |
2924 | =item SvNIOK |
2925 | |
2926 | Returns a boolean indicating whether the SV contains a number, integer or |
2927 | double. |
2928 | |
e89caa19 |
2929 | int SvNIOK (SV* SV) |
cb1a09d0 |
2930 | |
2931 | =item SvNIOK_off |
2932 | |
2933 | Unsets the NV/IV status of an SV. |
2934 | |
e89caa19 |
2935 | void SvNIOK_off (SV* sv) |
cb1a09d0 |
2936 | |
2937 | =item SvNIOKp |
2938 | |
2939 | Returns a boolean indicating whether the SV contains a number, integer or |
2940 | double. Checks the B<private> setting. Use C<SvNIOK>. |
2941 | |
e89caa19 |
2942 | int SvNIOKp (SV* SV) |
2943 | |
9cde0e7f |
2944 | =item PL_sv_no |
e89caa19 |
2945 | |
9cde0e7f |
2946 | This is the C<false> SV. See C<PL_sv_yes>. Always refer to this as C<&PL_sv_no>. |
cb1a09d0 |
2947 | |
2948 | =item SvNOK |
2949 | |
2950 | Returns a boolean indicating whether the SV contains a double. |
2951 | |
e89caa19 |
2952 | int SvNOK (SV* SV) |
cb1a09d0 |
2953 | |
2954 | =item SvNOK_off |
2955 | |
2956 | Unsets the NV status of an SV. |
2957 | |
e89caa19 |
2958 | void SvNOK_off (SV* sv) |
cb1a09d0 |
2959 | |
2960 | =item SvNOK_on |
2961 | |
2962 | Tells an SV that it is a double. |
2963 | |
e89caa19 |
2964 | void SvNOK_on (SV* sv) |
cb1a09d0 |
2965 | |
5fb8527f |
2966 | =item SvNOK_only |
2967 | |
2968 | Tells an SV that it is a double and disables all other OK bits. |
2969 | |
e89caa19 |
2970 | void SvNOK_only (SV* sv) |
5fb8527f |
2971 | |
cb1a09d0 |
2972 | =item SvNOKp |
2973 | |
2974 | Returns a boolean indicating whether the SV contains a double. Checks the |
2975 | B<private> setting. Use C<SvNOK>. |
2976 | |
e89caa19 |
2977 | int SvNOKp (SV* SV) |
cb1a09d0 |
2978 | |
2979 | =item SvNV |
2980 | |
5c68b227 |
2981 | Coerce the given SV to a double and return it. |
cb1a09d0 |
2982 | |
e89caa19 |
2983 | double SvNV (SV* sv) |
cb1a09d0 |
2984 | |
2985 | =item SvNVX |
2986 | |
5c68b227 |
2987 | Returns the double which is stored in the SV, assuming SvNOK is true. |
cb1a09d0 |
2988 | |
e89caa19 |
2989 | double SvNVX (SV* sv) |
2990 | |
2991 | =item SvOK |
2992 | |
2993 | Returns a boolean indicating whether the value is an SV. |
2994 | |
2995 | int SvOK (SV* sv) |
2996 | |
2997 | =item SvOOK |
2998 | |
2999 | Returns a boolean indicating whether the SvIVX is a valid offset value |
3000 | for the SvPVX. This hack is used internally to speed up removal of |
3001 | characters from the beginning of a SvPV. When SvOOK is true, then the |
3002 | start of the allocated string buffer is really (SvPVX - SvIVX). |
3003 | |
9cde0e7f |
3004 | int SvOOK(SV* sv) |
cb1a09d0 |
3005 | |
3006 | =item SvPOK |
3007 | |
3008 | Returns a boolean indicating whether the SV contains a character string. |
3009 | |
e89caa19 |
3010 | int SvPOK (SV* SV) |
cb1a09d0 |
3011 | |
3012 | =item SvPOK_off |
3013 | |
3014 | Unsets the PV status of an SV. |
3015 | |
e89caa19 |
3016 | void SvPOK_off (SV* sv) |
cb1a09d0 |
3017 | |
3018 | =item SvPOK_on |
3019 | |
3020 | Tells an SV that it is a string. |
3021 | |
e89caa19 |
3022 | void SvPOK_on (SV* sv) |
cb1a09d0 |
3023 | |
5fb8527f |
3024 | =item SvPOK_only |
3025 | |
3026 | Tells an SV that it is a string and disables all other OK bits. |
3027 | |
e89caa19 |
3028 | void SvPOK_only (SV* sv) |
5fb8527f |
3029 | |
cb1a09d0 |
3030 | =item SvPOKp |
3031 | |
3032 | Returns a boolean indicating whether the SV contains a character string. |
3033 | Checks the B<private> setting. Use C<SvPOK>. |
3034 | |
e89caa19 |
3035 | int SvPOKp (SV* SV) |
cb1a09d0 |
3036 | |
3037 | =item SvPV |
3038 | |
3039 | Returns a pointer to the string in the SV, or a stringified form of the SV |
2d8e6c8d |
3040 | if the SV does not contain a string. Handles 'get' magic. |
cb1a09d0 |
3041 | |
1fa8b10d |
3042 | char* SvPV (SV* sv, int len) |
e89caa19 |
3043 | |
3044 | =item SvPV_force |
3045 | |
3046 | Like <SvPV> but will force the SV into becoming a string (SvPOK). You |
3047 | want force if you are going to update the SvPVX directly. |
3048 | |
3049 | char* SvPV_force(SV* sv, int len) |
3050 | |
1fa8b10d |
3051 | =item SvPV_nolen |
3052 | |
3053 | Returns a pointer to the string in the SV, or a stringified form of the SV |
3054 | if the SV does not contain a string. Handles 'get' magic. |
3055 | |
3056 | char* SvPV (SV* sv) |
cb1a09d0 |
3057 | |
3058 | =item SvPVX |
3059 | |
3060 | Returns a pointer to the string in the SV. The SV must contain a string. |
3061 | |
e89caa19 |
3062 | char* SvPVX (SV* sv) |
cb1a09d0 |
3063 | |
3064 | =item SvREFCNT |
3065 | |
5f05dabc |
3066 | Returns the value of the object's reference count. |
cb1a09d0 |
3067 | |
e89caa19 |
3068 | int SvREFCNT (SV* sv) |
cb1a09d0 |
3069 | |
3070 | =item SvREFCNT_dec |
3071 | |
5f05dabc |
3072 | Decrements the reference count of the given SV. |
cb1a09d0 |
3073 | |
e89caa19 |
3074 | void SvREFCNT_dec (SV* sv) |
cb1a09d0 |
3075 | |
3076 | =item SvREFCNT_inc |
3077 | |
5f05dabc |
3078 | Increments the reference count of the given SV. |
cb1a09d0 |
3079 | |
e89caa19 |
3080 | void SvREFCNT_inc (SV* sv) |
cb1a09d0 |
3081 | |
3082 | =item SvROK |
3083 | |
3084 | Tests if the SV is an RV. |
3085 | |
e89caa19 |
3086 | int SvROK (SV* sv) |
cb1a09d0 |
3087 | |
3088 | =item SvROK_off |
3089 | |
3090 | Unsets the RV status of an SV. |
3091 | |
e89caa19 |
3092 | void SvROK_off (SV* sv) |
cb1a09d0 |
3093 | |
3094 | =item SvROK_on |
3095 | |
3096 | Tells an SV that it is an RV. |
3097 | |
e89caa19 |
3098 | void SvROK_on (SV* sv) |
cb1a09d0 |
3099 | |
3100 | =item SvRV |
3101 | |
3102 | Dereferences an RV to return the SV. |
3103 | |
ef50df4b |
3104 | SV* SvRV (SV* sv) |
cb1a09d0 |
3105 | |
189b2af5 |
3106 | =item SvSETMAGIC |
3107 | |
3108 | Invokes C<mg_set> on an SV if it has 'set' magic. This macro evaluates |
3109 | its argument more than once. |
3110 | |
3111 | void SvSETMAGIC( SV *sv ) |
3112 | |
ef50df4b |
3113 | =item sv_setiv |
189b2af5 |
3114 | |
ef50df4b |
3115 | Copies an integer into the given SV. Does not handle 'set' magic. |
3116 | See C<sv_setiv_mg>. |
189b2af5 |
3117 | |
ef50df4b |
3118 | void sv_setiv (SV* sv, IV num) |
189b2af5 |
3119 | |
ef50df4b |
3120 | =item sv_setiv_mg |
189b2af5 |
3121 | |
ef50df4b |
3122 | Like C<sv_setiv>, but also handles 'set' magic. |
189b2af5 |
3123 | |
ef50df4b |
3124 | void sv_setiv_mg (SV* sv, IV num) |
189b2af5 |
3125 | |
ef50df4b |
3126 | =item sv_setnv |
189b2af5 |
3127 | |
ef50df4b |
3128 | Copies a double into the given SV. Does not handle 'set' magic. |
3129 | See C<sv_setnv_mg>. |
189b2af5 |
3130 | |
ef50df4b |
3131 | void sv_setnv (SV* sv, double num) |
189b2af5 |
3132 | |
ef50df4b |
3133 | =item sv_setnv_mg |
189b2af5 |
3134 | |
ef50df4b |
3135 | Like C<sv_setnv>, but also handles 'set' magic. |
189b2af5 |
3136 | |
ef50df4b |
3137 | void sv_setnv_mg (SV* sv, double num) |
189b2af5 |
3138 | |
ef50df4b |
3139 | =item sv_setpv |
189b2af5 |
3140 | |
ef50df4b |
3141 | Copies a string into an SV. The string must be null-terminated. |
3142 | Does not handle 'set' magic. See C<sv_setpv_mg>. |
189b2af5 |
3143 | |
ef50df4b |
3144 | void sv_setpv (SV* sv, char* ptr) |
189b2af5 |
3145 | |
ef50df4b |
3146 | =item sv_setpv_mg |
189b2af5 |
3147 | |
ef50df4b |
3148 | Like C<sv_setpv>, but also handles 'set' magic. |
189b2af5 |
3149 | |
ef50df4b |
3150 | void sv_setpv_mg (SV* sv, char* ptr) |
189b2af5 |
3151 | |
ef50df4b |
3152 | =item sv_setpviv |
cb1a09d0 |
3153 | |
ef50df4b |
3154 | Copies an integer into the given SV, also updating its string value. |
3155 | Does not handle 'set' magic. See C<sv_setpviv_mg>. |
cb1a09d0 |
3156 | |
ef50df4b |
3157 | void sv_setpviv (SV* sv, IV num) |
cb1a09d0 |
3158 | |
ef50df4b |
3159 | =item sv_setpviv_mg |
cb1a09d0 |
3160 | |
ef50df4b |
3161 | Like C<sv_setpviv>, but also handles 'set' magic. |
cb1a09d0 |
3162 | |
ef50df4b |
3163 | void sv_setpviv_mg (SV* sv, IV num) |
cb1a09d0 |
3164 | |
ef50df4b |
3165 | =item sv_setpvn |
cb1a09d0 |
3166 | |
ef50df4b |
3167 | Copies a string into an SV. The C<len> parameter indicates the number of |
3168 | bytes to be copied. Does not handle 'set' magic. See C<sv_setpvn_mg>. |
cb1a09d0 |
3169 | |
ef50df4b |
3170 | void sv_setpvn (SV* sv, char* ptr, STRLEN len) |
cb1a09d0 |
3171 | |
ef50df4b |
3172 | =item sv_setpvn_mg |
189b2af5 |
3173 | |
ef50df4b |
3174 | Like C<sv_setpvn>, but also handles 'set' magic. |
189b2af5 |
3175 | |
ef50df4b |
3176 | void sv_setpvn_mg (SV* sv, char* ptr, STRLEN len) |
189b2af5 |
3177 | |
ef50df4b |
3178 | =item sv_setpvf |
cb1a09d0 |
3179 | |
ef50df4b |
3180 | Processes its arguments like C<sprintf> and sets an SV to the formatted |
3181 | output. Does not handle 'set' magic. See C<sv_setpvf_mg>. |
cb1a09d0 |
3182 | |
ef50df4b |
3183 | void sv_setpvf (SV* sv, const char* pat, ...) |
cb1a09d0 |
3184 | |
ef50df4b |
3185 | =item sv_setpvf_mg |
46fc3d4c |
3186 | |
ef50df4b |
3187 | Like C<sv_setpvf>, but also handles 'set' magic. |
46fc3d4c |
3188 | |
ef50df4b |
3189 | void sv_setpvf_mg (SV* sv, const char* pat, ...) |
46fc3d4c |
3190 | |
cb1a09d0 |
3191 | =item sv_setref_iv |
3192 | |
5fb8527f |
3193 | Copies an integer into a new SV, optionally blessing the SV. The C<rv> |
3194 | argument will be upgraded to an RV. That RV will be modified to point to |
3195 | the new SV. The C<classname> argument indicates the package for the |
3196 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
3197 | will be returned and will have a reference count of 1. |
cb1a09d0 |
3198 | |
ef50df4b |
3199 | SV* sv_setref_iv (SV *rv, char *classname, IV iv) |
cb1a09d0 |
3200 | |
3201 | =item sv_setref_nv |
3202 | |
5fb8527f |
3203 | Copies a double into a new SV, optionally blessing the SV. The C<rv> |
3204 | argument will be upgraded to an RV. That RV will be modified to point to |
3205 | the new SV. The C<classname> argument indicates the package for the |
3206 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
3207 | will be returned and will have a reference count of 1. |
cb1a09d0 |
3208 | |
ef50df4b |
3209 | SV* sv_setref_nv (SV *rv, char *classname, double nv) |
cb1a09d0 |
3210 | |
3211 | =item sv_setref_pv |
3212 | |
5fb8527f |
3213 | Copies a pointer into a new SV, optionally blessing the SV. The C<rv> |
3214 | argument will be upgraded to an RV. That RV will be modified to point to |
9cde0e7f |
3215 | the new SV. If the C<pv> argument is NULL then C<PL_sv_undef> will be placed |
5fb8527f |
3216 | into the SV. The C<classname> argument indicates the package for the |
3217 | blessing. Set C<classname> to C<Nullch> to avoid the blessing. The new SV |
5f05dabc |
3218 | will be returned and will have a reference count of 1. |
cb1a09d0 |
3219 | |
ef50df4b |
3220 | SV* sv_setref_pv (SV *rv, char *classname, void* pv) |
cb1a09d0 |
3221 | |
3222 | Do not use with integral Perl types such as HV, AV, SV, CV, because those |
3223 | objects will become corrupted by the pointer copy process. |
3224 | |
3225 | Note that C<sv_setref_pvn> copies the string while this copies the pointer. |
3226 | |
3227 | =item sv_setref_pvn |
3228 | |
5fb8527f |
3229 | Copies a string into a new SV, optionally blessing the SV. The length of the |
3230 | string must be specified with C<n>. The C<rv> argument will be upgraded to |
3231 | an RV. That RV will be modified to point to the new SV. The C<classname> |
cb1a09d0 |
3232 | argument indicates the package for the blessing. Set C<classname> to |
3233 | C<Nullch> to avoid the blessing. The new SV will be returned and will have |
5f05dabc |
3234 | a reference count of 1. |
cb1a09d0 |
3235 | |
ef50df4b |
3236 | SV* sv_setref_pvn (SV *rv, char *classname, char* pv, I32 n) |
cb1a09d0 |
3237 | |
3238 | Note that C<sv_setref_pv> copies the pointer while this copies the string. |
3239 | |
189b2af5 |
3240 | =item SvSetSV |
3241 | |
3242 | Calls C<sv_setsv> if dsv is not the same as ssv. May evaluate arguments |
3243 | more than once. |
3244 | |
3245 | void SvSetSV (SV* dsv, SV* ssv) |
3246 | |
3247 | =item SvSetSV_nosteal |
3248 | |
3249 | Calls a non-destructive version of C<sv_setsv> if dsv is not the same as ssv. |
3250 | May evaluate arguments more than once. |
3251 | |
3252 | void SvSetSV_nosteal (SV* dsv, SV* ssv) |
3253 | |
cb1a09d0 |
3254 | =item sv_setsv |
3255 | |
3256 | Copies the contents of the source SV C<ssv> into the destination SV C<dsv>. |
189b2af5 |
3257 | The source SV may be destroyed if it is mortal. Does not handle 'set' magic. |
ef50df4b |
3258 | See the macro forms C<SvSetSV>, C<SvSetSV_nosteal> and C<sv_setsv_mg>. |
3259 | |
3260 | void sv_setsv (SV* dsv, SV* ssv) |
3261 | |
3262 | =item sv_setsv_mg |
3263 | |
3264 | Like C<sv_setsv>, but also handles 'set' magic. |
cb1a09d0 |
3265 | |
ef50df4b |
3266 | void sv_setsv_mg (SV* dsv, SV* ssv) |
cb1a09d0 |
3267 | |
189b2af5 |
3268 | =item sv_setuv |
3269 | |
3270 | Copies an unsigned integer into the given SV. Does not handle 'set' magic. |
ef50df4b |
3271 | See C<sv_setuv_mg>. |
189b2af5 |
3272 | |
ef50df4b |
3273 | void sv_setuv (SV* sv, UV num) |
3274 | |
3275 | =item sv_setuv_mg |
3276 | |
3277 | Like C<sv_setuv>, but also handles 'set' magic. |
3278 | |
3279 | void sv_setuv_mg (SV* sv, UV num) |
189b2af5 |
3280 | |
cb1a09d0 |
3281 | =item SvSTASH |
3282 | |
3283 | Returns the stash of the SV. |
3284 | |
e89caa19 |
3285 | HV* SvSTASH (SV* sv) |
3286 | |
3287 | =item SvTAINT |
3288 | |
3289 | Taints an SV if tainting is enabled |
3290 | |
3291 | void SvTAINT (SV* sv) |
3292 | |
3293 | =item SvTAINTED |
3294 | |
3295 | Checks to see if an SV is tainted. Returns TRUE if it is, FALSE if not. |
3296 | |
3297 | int SvTAINTED (SV* sv) |
3298 | |
3299 | =item SvTAINTED_off |
3300 | |
3301 | Untaints an SV. Be I<very> careful with this routine, as it short-circuits |
3302 | some of Perl's fundamental security features. XS module authors should |
3303 | not use this function unless they fully understand all the implications |
3304 | of unconditionally untainting the value. Untainting should be done in |
3305 | the standard perl fashion, via a carefully crafted regexp, rather than |
3306 | directly untainting variables. |
3307 | |
3308 | void SvTAINTED_off (SV* sv) |
3309 | |
3310 | =item SvTAINTED_on |
3311 | |
3312 | Marks an SV as tainted. |
3313 | |
3314 | void SvTAINTED_on (SV* sv) |
cb1a09d0 |
3315 | |
3316 | =item SVt_IV |
3317 | |
3318 | Integer type flag for scalars. See C<svtype>. |
3319 | |
3320 | =item SVt_PV |
3321 | |
3322 | Pointer type flag for scalars. See C<svtype>. |
3323 | |
3324 | =item SVt_PVAV |
3325 | |
3326 | Type flag for arrays. See C<svtype>. |
3327 | |
3328 | =item SVt_PVCV |
3329 | |
3330 | Type flag for code refs. See C<svtype>. |
3331 | |
3332 | =item SVt_PVHV |
3333 | |
3334 | Type flag for hashes. See C<svtype>. |
3335 | |
3336 | =item SVt_PVMG |
3337 | |
3338 | Type flag for blessed scalars. See C<svtype>. |
3339 | |
3340 | =item SVt_NV |
3341 | |
3342 | Double type flag for scalars. See C<svtype>. |
3343 | |
3344 | =item SvTRUE |
3345 | |
3346 | Returns a boolean indicating whether Perl would evaluate the SV as true or |
189b2af5 |
3347 | false, defined or undefined. Does not handle 'get' magic. |
cb1a09d0 |
3348 | |
e89caa19 |
3349 | int SvTRUE (SV* sv) |
cb1a09d0 |
3350 | |
3351 | =item SvTYPE |
3352 | |
3353 | Returns the type of the SV. See C<svtype>. |
3354 | |
3355 | svtype SvTYPE (SV* sv) |
3356 | |
3357 | =item svtype |
3358 | |
3359 | An enum of flags for Perl types. These are found in the file B<sv.h> in the |
3360 | C<svtype> enum. Test these flags with the C<SvTYPE> macro. |
3361 | |
9cde0e7f |
3362 | =item PL_sv_undef |
cb1a09d0 |
3363 | |
9cde0e7f |
3364 | This is the C<undef> SV. Always refer to this as C<&PL_sv_undef>. |
cb1a09d0 |
3365 | |
5fb8527f |
3366 | =item sv_unref |
3367 | |
07fa94a1 |
3368 | Unsets the RV status of the SV, and decrements the reference count of |
3369 | whatever was being referenced by the RV. This can almost be thought of |
3370 | as a reversal of C<newSVrv>. See C<SvROK_off>. |
5fb8527f |
3371 | |
ef50df4b |
3372 | void sv_unref (SV* sv) |
189b2af5 |
3373 | |
e89caa19 |
3374 | =item SvUPGRADE |
3375 | |
3376 | Used to upgrade an SV to a more complex form. Uses C<sv_upgrade> to perform |
3377 | the upgrade if necessary. See C<svtype>. |
3378 | |
3379 | bool SvUPGRADE (SV* sv, svtype mt) |
3380 | |
3381 | =item sv_upgrade |
3382 | |
3383 | Upgrade an SV to a more complex form. Use C<SvUPGRADE>. See C<svtype>. |
3384 | |
cb1a09d0 |
3385 | =item sv_usepvn |
3386 | |
3387 | Tells an SV to use C<ptr> to find its string value. Normally the string is |
5fb8527f |
3388 | stored inside the SV but sv_usepvn allows the SV to use an outside string. |
3389 | The C<ptr> should point to memory that was allocated by C<malloc>. The |
cb1a09d0 |
3390 | string length, C<len>, must be supplied. This function will realloc the |
3391 | memory pointed to by C<ptr>, so that pointer should not be freed or used by |
189b2af5 |
3392 | the programmer after giving it to sv_usepvn. Does not handle 'set' magic. |
ef50df4b |
3393 | See C<sv_usepvn_mg>. |
3394 | |
3395 | void sv_usepvn (SV* sv, char* ptr, STRLEN len) |
3396 | |
3397 | =item sv_usepvn_mg |
3398 | |
3399 | Like C<sv_usepvn>, but also handles 'set' magic. |
cb1a09d0 |
3400 | |
ef50df4b |
3401 | void sv_usepvn_mg (SV* sv, char* ptr, STRLEN len) |
cb1a09d0 |
3402 | |
9abd00ed |
3403 | =item sv_vcatpvfn(sv, pat, patlen, args, svargs, svmax, used_locale) |
3404 | |
3405 | Processes its arguments like C<vsprintf> and appends the formatted output |
3406 | to an SV. Uses an array of SVs if the C style variable argument list is |
3407 | missing (NULL). Indicates if locale information has been used for formatting. |
3408 | |
3409 | void sv_catpvfn _((SV* sv, const char* pat, STRLEN patlen, |
3410 | va_list *args, SV **svargs, I32 svmax, |
3411 | bool *used_locale)); |
3412 | |
3413 | =item sv_vsetpvfn(sv, pat, patlen, args, svargs, svmax, used_locale) |
3414 | |
3415 | Works like C<vcatpvfn> but copies the text into the SV instead of |
3416 | appending it. |
3417 | |
3418 | void sv_setpvfn _((SV* sv, const char* pat, STRLEN patlen, |
3419 | va_list *args, SV **svargs, I32 svmax, |
3420 | bool *used_locale)); |
3421 | |
e89caa19 |
3422 | =item SvUV |
3423 | |
5c68b227 |
3424 | Coerces the given SV to an unsigned integer and returns it. |
e89caa19 |
3425 | |
3426 | UV SvUV(SV* sv) |
3427 | |
3428 | =item SvUVX |
3429 | |
5c68b227 |
3430 | Returns the unsigned integer which is stored in the SV, assuming SvIOK is true. |
e89caa19 |
3431 | |
3432 | UV SvUVX(SV* sv) |
3433 | |
9cde0e7f |
3434 | =item PL_sv_yes |
cb1a09d0 |
3435 | |
9cde0e7f |
3436 | This is the C<true> SV. See C<PL_sv_no>. Always refer to this as C<&PL_sv_yes>. |
cb1a09d0 |
3437 | |
3438 | =item THIS |
3439 | |
3440 | Variable which is setup by C<xsubpp> to designate the object in a C++ XSUB. |
3441 | This is always the proper type for the C++ object. See C<CLASS> and |
5fb8527f |
3442 | L<perlxs/"Using XS With C++">. |
cb1a09d0 |
3443 | |
3444 | =item toLOWER |
3445 | |
3446 | Converts the specified character to lowercase. |
3447 | |
e89caa19 |
3448 | int toLOWER (char c) |
cb1a09d0 |
3449 | |
3450 | =item toUPPER |
3451 | |
3452 | Converts the specified character to uppercase. |
3453 | |
e89caa19 |
3454 | int toUPPER (char c) |
cb1a09d0 |
3455 | |
3456 | =item warn |
3457 | |
3458 | This is the XSUB-writer's interface to Perl's C<warn> function. Use this |
3459 | function the same way you use the C C<printf> function. See C<croak()>. |
3460 | |
3461 | =item XPUSHi |
3462 | |
189b2af5 |
3463 | Push an integer onto the stack, extending the stack if necessary. Handles |
3464 | 'set' magic. See C<PUSHi>. |
cb1a09d0 |
3465 | |
3466 | XPUSHi(int d) |
3467 | |
3468 | =item XPUSHn |
3469 | |
189b2af5 |
3470 | Push a double onto the stack, extending the stack if necessary. Handles 'set' |
3471 | magic. See C<PUSHn>. |
cb1a09d0 |
3472 | |
3473 | XPUSHn(double d) |
3474 | |
3475 | =item XPUSHp |
3476 | |
3477 | Push a string onto the stack, extending the stack if necessary. The C<len> |
189b2af5 |
3478 | indicates the length of the string. Handles 'set' magic. See C<PUSHp>. |
cb1a09d0 |
3479 | |
3480 | XPUSHp(char *c, int len) |
3481 | |
3482 | =item XPUSHs |
3483 | |
189b2af5 |
3484 | Push an SV onto the stack, extending the stack if necessary. Does not |
3485 | handle 'set' magic. See C<PUSHs>. |
cb1a09d0 |
3486 | |
3487 | XPUSHs(sv) |
3488 | |
e89caa19 |
3489 | =item XPUSHu |
3490 | |
3491 | Push an unsigned integer onto the stack, extending the stack if |
3492 | necessary. See C<PUSHu>. |
3493 | |
5fb8527f |
3494 | =item XS |
3495 | |
3496 | Macro to declare an XSUB and its C parameter list. This is handled by |
3497 | C<xsubpp>. |
3498 | |
cb1a09d0 |
3499 | =item XSRETURN |
3500 | |
3501 | Return from XSUB, indicating number of items on the stack. This is usually |
3502 | handled by C<xsubpp>. |
3503 | |
ef50df4b |
3504 | XSRETURN(int x) |
cb1a09d0 |
3505 | |
3506 | =item XSRETURN_EMPTY |
3507 | |
5fb8527f |
3508 | Return an empty list from an XSUB immediately. |
cb1a09d0 |
3509 | |
3510 | XSRETURN_EMPTY; |
3511 | |
5fb8527f |
3512 | =item XSRETURN_IV |
3513 | |
3514 | Return an integer from an XSUB immediately. Uses C<XST_mIV>. |
3515 | |
ef50df4b |
3516 | XSRETURN_IV(IV v) |
5fb8527f |
3517 | |
cb1a09d0 |
3518 | =item XSRETURN_NO |
3519 | |
9cde0e7f |
3520 | Return C<&PL_sv_no> from an XSUB immediately. Uses C<XST_mNO>. |
cb1a09d0 |
3521 | |
3522 | XSRETURN_NO; |
3523 | |
5fb8527f |
3524 | =item XSRETURN_NV |
3525 | |
3526 | Return an double from an XSUB immediately. Uses C<XST_mNV>. |
3527 | |
ef50df4b |
3528 | XSRETURN_NV(NV v) |
5fb8527f |
3529 | |
3530 | =item XSRETURN_PV |
3531 | |
3532 | Return a copy of a string from an XSUB immediately. Uses C<XST_mPV>. |
3533 | |
ef50df4b |
3534 | XSRETURN_PV(char *v) |
5fb8527f |
3535 | |
cb1a09d0 |
3536 | =item XSRETURN_UNDEF |
3537 | |
9cde0e7f |
3538 | Return C<&PL_sv_undef> from an XSUB immediately. Uses C<XST_mUNDEF>. |
cb1a09d0 |
3539 | |
3540 | XSRETURN_UNDEF; |
3541 | |
3542 | =item XSRETURN_YES |
3543 | |
9cde0e7f |
3544 | Return C<&PL_sv_yes> from an XSUB immediately. Uses C<XST_mYES>. |
cb1a09d0 |
3545 | |
3546 | XSRETURN_YES; |
3547 | |
5fb8527f |
3548 | =item XST_mIV |
3549 | |
3550 | Place an integer into the specified position C<i> on the stack. The value is |
3551 | stored in a new mortal SV. |
3552 | |
ef50df4b |
3553 | XST_mIV( int i, IV v ) |
5fb8527f |
3554 | |
3555 | =item XST_mNV |
3556 | |
3557 | Place a double into the specified position C<i> on the stack. The value is |
3558 | stored in a new mortal SV. |
3559 | |
ef50df4b |
3560 | XST_mNV( int i, NV v ) |
5fb8527f |
3561 | |
3562 | =item XST_mNO |
3563 | |
9cde0e7f |
3564 | Place C<&PL_sv_no> into the specified position C<i> on the stack. |
5fb8527f |
3565 | |
ef50df4b |
3566 | XST_mNO( int i ) |
5fb8527f |
3567 | |
3568 | =item XST_mPV |
3569 | |
3570 | Place a copy of a string into the specified position C<i> on the stack. The |
3571 | value is stored in a new mortal SV. |
3572 | |
ef50df4b |
3573 | XST_mPV( int i, char *v ) |
5fb8527f |
3574 | |
3575 | =item XST_mUNDEF |
3576 | |
9cde0e7f |
3577 | Place C<&PL_sv_undef> into the specified position C<i> on the stack. |
5fb8527f |
3578 | |
ef50df4b |
3579 | XST_mUNDEF( int i ) |
5fb8527f |
3580 | |
3581 | =item XST_mYES |
3582 | |
9cde0e7f |
3583 | Place C<&PL_sv_yes> into the specified position C<i> on the stack. |
5fb8527f |
3584 | |
ef50df4b |
3585 | XST_mYES( int i ) |
5fb8527f |
3586 | |
3587 | =item XS_VERSION |
3588 | |
3589 | The version identifier for an XS module. This is usually handled |
3590 | automatically by C<ExtUtils::MakeMaker>. See C<XS_VERSION_BOOTCHECK>. |
3591 | |
3592 | =item XS_VERSION_BOOTCHECK |
3593 | |
3594 | Macro to verify that a PM module's $VERSION variable matches the XS module's |
3595 | C<XS_VERSION> variable. This is usually handled automatically by |
3596 | C<xsubpp>. See L<perlxs/"The VERSIONCHECK: Keyword">. |
3597 | |
cb1a09d0 |
3598 | =item Zero |
3599 | |
3600 | The XSUB-writer's interface to the C C<memzero> function. The C<d> is the |
3601 | destination, C<n> is the number of items, and C<t> is the type. |
3602 | |
e89caa19 |
3603 | void Zero( d, n, t ) |
cb1a09d0 |
3604 | |
3605 | =back |
3606 | |
9cecd9f2 |
3607 | =head1 AUTHORS |
cb1a09d0 |
3608 | |
9cecd9f2 |
3609 | Until May 1997, this document was maintained by Jeff Okamoto |
3610 | <okamoto@corp.hp.com>. It is now maintained as part of Perl itself. |
cb1a09d0 |
3611 | |
3612 | With lots of help and suggestions from Dean Roehrich, Malcolm Beattie, |
3613 | Andreas Koenig, Paul Hudson, Ilya Zakharevich, Paul Marquess, Neil |
189b2af5 |
3614 | Bowers, Matthew Green, Tim Bunce, Spider Boardman, Ulrich Pfeifer, |
3615 | Stephen McCamant, and Gurusamy Sarathy. |
cb1a09d0 |
3616 | |
9cecd9f2 |
3617 | API Listing originally by Dean Roehrich <roehrich@cray.com>. |