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69bcf1d3 FC |
1 | #!/usr/bin/perl |
2 | # | |
3 | # Regenerate (overwriting only if changed): | |
4 | # | |
5 | # lib/feature.pm | |
f2c01b15 | 6 | # feature.h |
69bcf1d3 | 7 | # |
3489ea76 | 8 | # from information hardcoded into this script and from two #defines |
d73d634c | 9 | # in perl.h. |
69bcf1d3 FC |
10 | # |
11 | # This script is normally invoked from regen.pl. | |
12 | ||
13 | BEGIN { | |
3d7c117d | 14 | require './regen/regen_lib.pl'; |
69bcf1d3 FC |
15 | push @INC, './lib'; |
16 | } | |
69bcf1d3 | 17 | |
3b8e6999 N |
18 | use strict; |
19 | use warnings; | |
c452a42f FC |
20 | |
21 | ########################################################################### | |
22 | # Hand-editable data | |
23 | ||
c6b36e45 | 24 | # (feature name) => (internal name, used in %^H and macro names) |
69bcf1d3 | 25 | my %feature = ( |
67bdaa9e FC |
26 | say => 'say', |
27 | state => 'state', | |
28 | switch => 'switch', | |
cec892e7 | 29 | bitwise => 'bitwise', |
67bdaa9e FC |
30 | evalbytes => 'evalbytes', |
31 | current_sub => '__SUB__', | |
baabe3fb | 32 | refaliasing => 'refaliasing', |
158becca | 33 | postderef_qq => 'postderef_qq', |
67bdaa9e | 34 | unicode_eval => 'unieval', |
82d83da3 | 35 | declared_refs => 'myref', |
67bdaa9e | 36 | unicode_strings => 'unicode', |
2a4315f8 | 37 | fc => 'fc', |
30d9c59b | 38 | signatures => 'signatures', |
813e85a0 | 39 | isa => 'isa', |
0b657b19 | 40 | indirect => 'indirect', |
1ad5a39c | 41 | multidimensional => 'multidimensional', |
69bcf1d3 FC |
42 | ); |
43 | ||
40e4d872 FC |
44 | # NOTE: If a feature is ever enabled in a non-contiguous range of Perl |
45 | # versions, any code below that uses %BundleRanges will have to | |
46 | # be changed to account. | |
47 | ||
52fc5c56 | 48 | # 5.odd implies the next 5.even, but an explicit 5.even can override it. |
3b8e6999 N |
49 | |
50 | # features bundles | |
1ad5a39c | 51 | use constant V5_9_5 => sort qw{say state switch indirect multidimensional}; |
3b8e6999 N |
52 | use constant V5_11 => sort ( +V5_9_5, qw{unicode_strings} ); |
53 | use constant V5_15 => sort ( +V5_11, qw{unicode_eval evalbytes current_sub fc} ); | |
54 | use constant V5_23 => sort ( +V5_15, qw{postderef_qq} ); | |
55 | use constant V5_27 => sort ( +V5_23, qw{bitwise} ); | |
56 | ||
69bcf1d3 | 57 | my %feature_bundle = ( |
3b8e6999 | 58 | all => [ sort keys %feature ], |
1ad5a39c | 59 | default => [ qw{indirect multidimensional} ], |
3b8e6999 N |
60 | # using 5.9.5 features bundle |
61 | "5.9.5" => [ +V5_9_5 ], | |
62 | "5.10" => [ +V5_9_5 ], | |
63 | # using 5.11 features bundle | |
64 | "5.11" => [ +V5_11 ], | |
65 | "5.13" => [ +V5_11 ], | |
66 | # using 5.15 features bundle | |
67 | "5.15" => [ +V5_15 ], | |
68 | "5.17" => [ +V5_15 ], | |
69 | "5.19" => [ +V5_15 ], | |
70 | "5.21" => [ +V5_15 ], | |
71 | # using 5.23 features bundle | |
72 | "5.23" => [ +V5_23 ], | |
73 | "5.25" => [ +V5_23 ], | |
74 | # using 5.27 features bundle | |
75 | "5.27" => [ +V5_27 ], | |
76 | "5.29" => [ +V5_27 ], | |
77 | "5.31" => [ +V5_27 ], | |
78 | "5.33" => [ +V5_27 ], | |
69bcf1d3 FC |
79 | ); |
80 | ||
db629560 | 81 | my @noops = qw( postderef lexical_subs ); |
c22e17d0 | 82 | my @removed = qw( array_base ); |
db629560 | 83 | |
c452a42f | 84 | |
69bcf1d3 | 85 | ########################################################################### |
c452a42f | 86 | # More data generated from the above |
69bcf1d3 | 87 | |
9f601cf3 TC |
88 | if (keys %feature > 32) { |
89 | die "cop_features only has room for 32 features"; | |
90 | } | |
91 | ||
92 | my %feature_bits; | |
93 | my $mask = 1; | |
94 | for my $feature (sort keys %feature) { | |
95 | $feature_bits{$feature} = $mask; | |
96 | $mask <<= 1; | |
97 | } | |
98 | ||
52fc5c56 FC |
99 | for (keys %feature_bundle) { |
100 | next unless /^5\.(\d*[13579])\z/; | |
101 | $feature_bundle{"5.".($1+1)} ||= $feature_bundle{$_}; | |
102 | } | |
103 | ||
f2c01b15 FC |
104 | my %UniqueBundles; # "say state switch" => 5.10 |
105 | my %Aliases; # 5.12 => 5.11 | |
106 | for( sort keys %feature_bundle ) { | |
107 | my $value = join(' ', sort @{$feature_bundle{$_}}); | |
108 | if (exists $UniqueBundles{$value}) { | |
109 | $Aliases{$_} = $UniqueBundles{$value}; | |
110 | } | |
111 | else { | |
112 | $UniqueBundles{$value} = $_; | |
113 | } | |
114 | } | |
40e4d872 FC |
115 | # start end |
116 | my %BundleRanges; # say => ['5.10', '5.15'] # unique bundles for values | |
117 | for my $bund ( | |
118 | sort { $a eq 'default' ? -1 : $b eq 'default' ? 1 : $a cmp $b } | |
119 | values %UniqueBundles | |
120 | ) { | |
03222170 | 121 | next if $bund =~ /[^\d.]/ and $bund ne 'default'; |
40e4d872 FC |
122 | for (@{$feature_bundle{$bund}}) { |
123 | if (@{$BundleRanges{$_} ||= []} == 2) { | |
124 | $BundleRanges{$_}[1] = $bund | |
125 | } | |
126 | else { | |
127 | push @{$BundleRanges{$_}}, $bund; | |
128 | } | |
129 | } | |
130 | } | |
69bcf1d3 | 131 | |
47222a2d | 132 | my $HintShift; |
ada44f8c | 133 | my $HintMask; |
3489ea76 | 134 | my $Uni8Bit; |
47222a2d | 135 | |
1ae6ead9 | 136 | open "perl.h", "<", "perl.h" or die "$0 cannot open perl.h: $!"; |
3489ea76 FC |
137 | while (readline "perl.h") { |
138 | next unless /#\s*define\s+(HINT_FEATURE_MASK|HINT_UNI_8_BIT)/; | |
139 | my $is_u8b = $1 =~ 8; | |
140 | /(0x[A-Fa-f0-9]+)/ or die "No hex number in:\n\n$_\n "; | |
141 | if ($is_u8b) { | |
142 | $Uni8Bit = $1; | |
143 | } | |
144 | else { | |
ada44f8c | 145 | my $hex = $HintMask = $1; |
47222a2d FC |
146 | my $bits = sprintf "%b", oct $1; |
147 | $bits =~ /^0*1+(0*)\z/ | |
148 | or die "Non-contiguous bits in $bits (binary for $hex):\n\n$_\n "; | |
149 | $HintShift = length $1; | |
150 | my $bits_needed = | |
151 | length sprintf "%b", scalar keys %UniqueBundles; | |
152 | $bits =~ /1{$bits_needed}/ | |
153 | or die "Not enough bits (need $bits_needed)" | |
5d826eae | 154 | . " in $bits (binary for $hex):\n\n$_\n "; |
47222a2d | 155 | } |
3489ea76 | 156 | if ($Uni8Bit && $HintMask) { last } |
47222a2d | 157 | } |
3489ea76 FC |
158 | die "No HINT_FEATURE_MASK defined in perl.h" unless $HintMask; |
159 | die "No HINT_UNI_8_BIT defined in perl.h" unless $Uni8Bit; | |
160 | ||
47222a2d FC |
161 | close "perl.h"; |
162 | ||
ada44f8c FC |
163 | my @HintedBundles = |
164 | ('default', grep !/[^\d.]/, sort values %UniqueBundles); | |
165 | ||
47222a2d | 166 | |
f2c01b15 | 167 | ########################################################################### |
c452a42f | 168 | # Open files to be generated |
f2c01b15 FC |
169 | |
170 | my ($pm, $h) = map { | |
69bcf1d3 | 171 | open_new($_, '>', { by => 'regen/feature.pl' }); |
f2c01b15 | 172 | } 'lib/feature.pm', 'feature.h'; |
69bcf1d3 FC |
173 | |
174 | ||
c452a42f FC |
175 | ########################################################################### |
176 | # Generate lib/feature.pm | |
177 | ||
69bcf1d3 FC |
178 | while (<DATA>) { |
179 | last if /^FEATURES$/ ; | |
180 | print $pm $_ ; | |
181 | } | |
182 | ||
183 | sub longest { | |
184 | my $long; | |
185 | for(@_) { | |
186 | if (!defined $long or length $long < length) { | |
187 | $long = $_; | |
188 | } | |
189 | } | |
190 | $long; | |
191 | } | |
192 | ||
0bb01b05 | 193 | print $pm "our %feature = (\n"; |
69bcf1d3 | 194 | my $width = length longest keys %feature; |
ebd25686 | 195 | for(sort { length $a <=> length $b || $a cmp $b } keys %feature) { |
67bdaa9e FC |
196 | print $pm " $_" . " "x($width-length) |
197 | . " => 'feature_$feature{$_}',\n"; | |
69bcf1d3 FC |
198 | } |
199 | print $pm ");\n\n"; | |
200 | ||
69bcf1d3 | 201 | print $pm "our %feature_bundle = (\n"; |
9f601cf3 | 202 | my $bund_width = length longest values %UniqueBundles; |
88da30d7 FC |
203 | for( sort { $UniqueBundles{$a} cmp $UniqueBundles{$b} } |
204 | keys %UniqueBundles ) { | |
205 | my $bund = $UniqueBundles{$_}; | |
9f601cf3 | 206 | print $pm qq' "$bund"' . " "x($bund_width-length $bund) |
88da30d7 | 207 | . qq' => [qw($_)],\n'; |
69bcf1d3 FC |
208 | } |
209 | print $pm ");\n\n"; | |
210 | ||
88da30d7 FC |
211 | for (sort keys %Aliases) { |
212 | print $pm | |
213 | qq'\$feature_bundle{"$_"} = \$feature_bundle{"$Aliases{$_}"};\n'; | |
214 | }; | |
69bcf1d3 | 215 | |
db629560 FC |
216 | print $pm "my \%noops = (\n"; |
217 | print $pm " $_ => 1,\n", for @noops; | |
218 | print $pm ");\n"; | |
219 | ||
c22e17d0 DIM |
220 | print $pm "my \%removed = (\n"; |
221 | print $pm " $_ => 1,\n", for @removed; | |
222 | print $pm ");\n"; | |
223 | ||
ada44f8c FC |
224 | print $pm <<EOPM; |
225 | ||
0bb01b05 FC |
226 | our \$hint_shift = $HintShift; |
227 | our \$hint_mask = $HintMask; | |
228 | our \@hint_bundles = qw( @HintedBundles ); | |
3489ea76 FC |
229 | |
230 | # This gets set (for now) in \$^H as well as in %^H, | |
231 | # for runtime speed of the uc/lc/ucfirst/lcfirst functions. | |
232 | # See HINT_UNI_8_BIT in perl.h. | |
233 | our \$hint_uni8bit = $Uni8Bit; | |
ada44f8c FC |
234 | EOPM |
235 | ||
69bcf1d3 FC |
236 | |
237 | while (<DATA>) { | |
2b3fe414 FC |
238 | last if /^PODTURES$/ ; |
239 | print $pm $_ ; | |
240 | } | |
241 | ||
242 | select +(select($pm), $~ = 'PODTURES')[0]; | |
243 | format PODTURES = | |
244 | ^<<<<<<<< ^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<~~ | |
245 | $::bundle, $::feature | |
246 | . | |
247 | ||
248 | for ('default', sort grep /\.\d[02468]/, keys %feature_bundle) { | |
249 | $::bundle = ":$_"; | |
250 | $::feature = join ' ', @{$feature_bundle{$_}}; | |
251 | write $pm; | |
252 | print $pm "\n"; | |
253 | } | |
254 | ||
255 | while (<DATA>) { | |
69bcf1d3 FC |
256 | print $pm $_ ; |
257 | } | |
258 | ||
259 | read_only_bottom_close_and_rename($pm); | |
260 | ||
c452a42f FC |
261 | |
262 | ########################################################################### | |
263 | # Generate feature.h | |
264 | ||
f2c01b15 FC |
265 | print $h <<EOH; |
266 | ||
3dd7db29 JK |
267 | #ifndef PERL_FEATURE_H_ |
268 | #define PERL_FEATURE_H_ | |
269 | ||
f2c01b15 FC |
270 | #if defined(PERL_CORE) || defined (PERL_EXT) |
271 | ||
272 | #define HINT_FEATURE_SHIFT $HintShift | |
273 | ||
f2c01b15 FC |
274 | EOH |
275 | ||
9f601cf3 TC |
276 | for (sort keys %feature_bits) { |
277 | printf $h "#define FEATURE_%s_BIT%*s %#06x\n", uc($feature{$_}), | |
278 | $width-length($feature{$_}), "", $feature_bits{$_}; | |
279 | } | |
280 | print $h "\n"; | |
281 | ||
f2c01b15 | 282 | my $count; |
016d11cb FC |
283 | for (@HintedBundles) { |
284 | (my $key = uc) =~ y/.//d; | |
285 | print $h "#define FEATURE_BUNDLE_$key ", $count++, "\n"; | |
f2c01b15 FC |
286 | } |
287 | ||
7d058bc9 | 288 | print $h <<'EOH'; |
2b9e0ab7 | 289 | #define FEATURE_BUNDLE_CUSTOM (HINT_FEATURE_MASK >> HINT_FEATURE_SHIFT) |
f2c01b15 | 290 | |
7d058bc9 | 291 | #define CURRENT_HINTS \ |
d1fd0100 | 292 | (PL_curcop == &PL_compiling ? PL_hints : PL_curcop->cop_hints) |
035b6821 FC |
293 | #define CURRENT_FEATURE_BUNDLE \ |
294 | ((CURRENT_HINTS & HINT_FEATURE_MASK) >> HINT_FEATURE_SHIFT) | |
d1fd0100 | 295 | |
9f601cf3 TC |
296 | #define FEATURE_IS_ENABLED_MASK(mask) \ |
297 | ((CURRENT_HINTS & HINT_LOCALIZE_HH) \ | |
298 | ? (PL_curcop->cop_features & (mask)) : FALSE) | |
299 | ||
7d058bc9 | 300 | /* The longest string we pass in. */ |
03222170 FC |
301 | EOH |
302 | ||
1b6e8741 FC |
303 | my $longest_internal_feature_name = longest values %feature; |
304 | print $h <<EOL; | |
305 | #define MAX_FEATURE_LEN (sizeof("$longest_internal_feature_name")-1) | |
306 | ||
307 | EOL | |
308 | ||
03222170 | 309 | for ( |
ebd25686 | 310 | sort { length $a <=> length $b || $a cmp $b } keys %feature |
03222170 FC |
311 | ) { |
312 | my($first,$last) = | |
313 | map { (my $__ = uc) =~ y/.//d; $__ } @{$BundleRanges{$_}}; | |
3fff3427 | 314 | my $name = $feature{$_}; |
03222170 | 315 | my $NAME = uc $name; |
f298f061 | 316 | if ($last && $first eq 'DEFAULT') { # '>= DEFAULT' warns |
beda0318 | 317 | print $h <<EOI; |
23fa16fc | 318 | #define FEATURE_${NAME}_IS_ENABLED \\ |
beda0318 FC |
319 | ( \\ |
320 | CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_$last \\ | |
321 | || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \\ | |
23fa16fc | 322 | FEATURE_IS_ENABLED_MASK(FEATURE_${NAME}_BIT)) \\ |
beda0318 FC |
323 | ) |
324 | ||
325 | EOI | |
326 | } | |
327 | elsif ($last) { | |
03222170 | 328 | print $h <<EOH3; |
23fa16fc | 329 | #define FEATURE_${NAME}_IS_ENABLED \\ |
03222170 FC |
330 | ( \\ |
331 | (CURRENT_FEATURE_BUNDLE >= FEATURE_BUNDLE_$first && \\ | |
332 | CURRENT_FEATURE_BUNDLE <= FEATURE_BUNDLE_$last) \\ | |
333 | || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \\ | |
23fa16fc | 334 | FEATURE_IS_ENABLED_MASK(FEATURE_${NAME}_BIT)) \\ |
03222170 FC |
335 | ) |
336 | ||
337 | EOH3 | |
338 | } | |
ebd25686 | 339 | elsif ($first) { |
03222170 | 340 | print $h <<EOH4; |
23fa16fc | 341 | #define FEATURE_${NAME}_IS_ENABLED \\ |
03222170 FC |
342 | ( \\ |
343 | CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_$first \\ | |
344 | || (CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \\ | |
23fa16fc | 345 | FEATURE_IS_ENABLED_MASK(FEATURE_${NAME}_BIT)) \\ |
03222170 FC |
346 | ) |
347 | ||
348 | EOH4 | |
349 | } | |
ebd25686 FC |
350 | else { |
351 | print $h <<EOH5; | |
23fa16fc | 352 | #define FEATURE_${NAME}_IS_ENABLED \\ |
ebd25686 FC |
353 | ( \\ |
354 | CURRENT_FEATURE_BUNDLE == FEATURE_BUNDLE_CUSTOM && \\ | |
23fa16fc | 355 | FEATURE_IS_ENABLED_MASK(FEATURE_${NAME}_BIT) \\ |
ebd25686 FC |
356 | ) |
357 | ||
358 | EOH5 | |
359 | } | |
03222170 FC |
360 | } |
361 | ||
362 | print $h <<EOH; | |
363 | ||
9f601cf3 TC |
364 | #define SAVEFEATUREBITS() SAVEI32(PL_compiling.cop_features) |
365 | ||
366 | #define CLEARFEATUREBITS() (PL_compiling.cop_features = 0) | |
367 | ||
368 | #define STOREFEATUREBITSHH(hh) \\ | |
369 | (hv_stores((hh), "feature/bits", newSVuv(PL_compiling.cop_features))) | |
370 | ||
371 | #define FETCHFEATUREBITSHH(hh) \\ | |
372 | STMT_START { \\ | |
373 | SV **fbsv = hv_fetchs((hh), "feature/bits", FALSE); \\ | |
374 | PL_compiling.cop_features = fbsv ? SvUV(*fbsv) : 0; \\ | |
375 | } STMT_END | |
376 | ||
f2c01b15 | 377 | #endif /* PERL_CORE or PERL_EXT */ |
4160ddbd FC |
378 | |
379 | #ifdef PERL_IN_OP_C | |
380 | PERL_STATIC_INLINE void | |
381 | S_enable_feature_bundle(pTHX_ SV *ver) | |
382 | { | |
383 | SV *comp_ver = sv_newmortal(); | |
384 | PL_hints = (PL_hints &~ HINT_FEATURE_MASK) | |
385 | | ( | |
f2c01b15 FC |
386 | EOH |
387 | ||
4160ddbd FC |
388 | for (reverse @HintedBundles[1..$#HintedBundles]) { # skip default |
389 | my $numver = $_; | |
390 | if ($numver eq '5.10') { $numver = '5.009005' } # special case | |
391 | else { $numver =~ s/\./.0/ } # 5.11 => 5.011 | |
392 | (my $macrover = $_) =~ y/.//d; | |
393 | print $h <<" EOK"; | |
394 | (sv_setnv(comp_ver, $numver), | |
395 | vcmp(ver, upg_version(comp_ver, FALSE)) >= 0) | |
396 | ? FEATURE_BUNDLE_$macrover : | |
397 | EOK | |
398 | } | |
399 | ||
400 | print $h <<EOJ; | |
401 | FEATURE_BUNDLE_DEFAULT | |
402 | ) << HINT_FEATURE_SHIFT; | |
6389c777 FC |
403 | /* special case */ |
404 | assert(PL_curcop == &PL_compiling); | |
405 | if (FEATURE_UNICODE_IS_ENABLED) PL_hints |= HINT_UNI_8_BIT; | |
406 | else PL_hints &= ~HINT_UNI_8_BIT; | |
4160ddbd FC |
407 | } |
408 | #endif /* PERL_IN_OP_C */ | |
3dd7db29 | 409 | |
b34c1a7e TC |
410 | #ifdef PERL_IN_MG_C |
411 | ||
412 | #define magic_sethint_feature(keysv, keypv, keylen, valsv, valbool) \\ | |
413 | S_magic_sethint_feature(aTHX_ (keysv), (keypv), (keylen), (valsv), (valbool)) | |
414 | PERL_STATIC_INLINE void | |
415 | S_magic_sethint_feature(pTHX_ SV *keysv, const char *keypv, STRLEN keylen, | |
416 | SV *valsv, bool valbool) { | |
417 | if (keysv) | |
418 | keypv = SvPV_const(keysv, keylen); | |
419 | ||
420 | if (memBEGINs(keypv, keylen, "feature_")) { | |
421 | const char *subf = keypv + (sizeof("feature_")-1); | |
422 | U32 mask = 0; | |
423 | switch (*subf) { | |
424 | EOJ | |
425 | ||
426 | my %pref; | |
427 | for my $key (sort values %feature) { | |
428 | push @{$pref{substr($key, 0, 1)}}, $key; | |
429 | } | |
430 | ||
431 | for my $pref (sort keys %pref) { | |
432 | print $h <<EOS; | |
433 | case '$pref': | |
434 | EOS | |
435 | my $first = 1; | |
436 | for my $subkey (@{$pref{$pref}}) { | |
437 | my $rest = substr($subkey, 1); | |
438 | my $if = $first ? "if" : "else if"; | |
439 | print $h <<EOJ; | |
440 | $if (keylen == sizeof("feature_$subkey")-1 | |
441 | && memcmp(subf+1, "$rest", keylen - sizeof("feature_")) == 0) { | |
442 | mask = FEATURE_\U${subkey}\E_BIT; | |
443 | break; | |
444 | } | |
445 | EOJ | |
446 | ||
447 | $first = 0; | |
448 | } | |
449 | print $h <<EOS; | |
450 | return; | |
451 | ||
452 | EOS | |
453 | } | |
454 | ||
455 | print $h <<EOJ; | |
456 | default: | |
457 | return; | |
458 | } | |
459 | if (valsv ? SvTRUE(valsv) : valbool) | |
460 | PL_compiling.cop_features |= mask; | |
461 | else | |
462 | PL_compiling.cop_features &= ~mask; | |
463 | } | |
464 | } | |
465 | #endif /* PERL_IN_MG_C */ | |
466 | ||
3dd7db29 | 467 | #endif /* PERL_FEATURE_H_ */ |
4160ddbd FC |
468 | EOJ |
469 | ||
f2c01b15 FC |
470 | read_only_bottom_close_and_rename($h); |
471 | ||
c452a42f FC |
472 | |
473 | ########################################################################### | |
474 | # Template for feature.pm | |
475 | ||
69bcf1d3 FC |
476 | __END__ |
477 | package feature; | |
478 | ||
3b8e6999 | 479 | our $VERSION = '1.60'; |
69bcf1d3 FC |
480 | |
481 | FEATURES | |
482 | ||
69bcf1d3 FC |
483 | # TODO: |
484 | # - think about versioned features (use feature switch => 2) | |
485 | ||
486 | =head1 NAME | |
487 | ||
488 | feature - Perl pragma to enable new features | |
489 | ||
490 | =head1 SYNOPSIS | |
491 | ||
492 | use feature qw(say switch); | |
493 | given ($foo) { | |
494 | when (1) { say "\$foo == 1" } | |
495 | when ([2,3]) { say "\$foo == 2 || \$foo == 3" } | |
496 | when (/^a[bc]d$/) { say "\$foo eq 'abd' || \$foo eq 'acd'" } | |
497 | when ($_ > 100) { say "\$foo > 100" } | |
498 | default { say "None of the above" } | |
499 | } | |
500 | ||
501 | use feature ':5.10'; # loads all features available in perl 5.10 | |
502 | ||
503 | use v5.10; # implicitly loads :5.10 feature bundle | |
504 | ||
505 | =head1 DESCRIPTION | |
506 | ||
507 | It is usually impossible to add new syntax to Perl without breaking | |
508 | some existing programs. This pragma provides a way to minimize that | |
509 | risk. New syntactic constructs, or new semantic meanings to older | |
510 | constructs, can be enabled by C<use feature 'foo'>, and will be parsed | |
511 | only when the appropriate feature pragma is in scope. (Nevertheless, the | |
512 | C<CORE::> prefix provides access to all Perl keywords, regardless of this | |
513 | pragma.) | |
514 | ||
515 | =head2 Lexical effect | |
516 | ||
517 | Like other pragmas (C<use strict>, for example), features have a lexical | |
301381dc | 518 | effect. C<use feature qw(foo)> will only make the feature "foo" available |
69bcf1d3 FC |
519 | from that point to the end of the enclosing block. |
520 | ||
521 | { | |
522 | use feature 'say'; | |
523 | say "say is available here"; | |
524 | } | |
525 | print "But not here.\n"; | |
526 | ||
527 | =head2 C<no feature> | |
528 | ||
529 | Features can also be turned off by using C<no feature "foo">. This too | |
530 | has lexical effect. | |
531 | ||
532 | use feature 'say'; | |
533 | say "say is available here"; | |
534 | { | |
535 | no feature 'say'; | |
536 | print "But not here.\n"; | |
537 | } | |
538 | say "Yet it is here."; | |
539 | ||
39ec54a5 RS |
540 | C<no feature> with no features specified will reset to the default group. To |
541 | disable I<all> features (an unusual request!) use C<no feature ':all'>. | |
69bcf1d3 FC |
542 | |
543 | =head1 AVAILABLE FEATURES | |
544 | ||
545 | =head2 The 'say' feature | |
546 | ||
547 | C<use feature 'say'> tells the compiler to enable the Perl 6 style | |
548 | C<say> function. | |
549 | ||
550 | See L<perlfunc/say> for details. | |
551 | ||
552 | This feature is available starting with Perl 5.10. | |
553 | ||
554 | =head2 The 'state' feature | |
555 | ||
556 | C<use feature 'state'> tells the compiler to enable C<state> | |
557 | variables. | |
558 | ||
559 | See L<perlsub/"Persistent Private Variables"> for details. | |
560 | ||
561 | This feature is available starting with Perl 5.10. | |
562 | ||
563 | =head2 The 'switch' feature | |
564 | ||
7caca87c DB |
565 | B<WARNING>: Because the L<smartmatch operator|perlop/"Smartmatch Operator"> is |
566 | experimental, Perl will warn when you use this feature, unless you have | |
567 | explicitly disabled the warning: | |
568 | ||
569 | no warnings "experimental::smartmatch"; | |
570 | ||
7896dde7 | 571 | C<use feature 'switch'> tells the compiler to enable the Perl 6 |
69bcf1d3 FC |
572 | given/when construct. |
573 | ||
48238296 | 574 | See L<perlsyn/"Switch Statements"> for details. |
69bcf1d3 FC |
575 | |
576 | This feature is available starting with Perl 5.10. | |
577 | ||
578 | =head2 The 'unicode_strings' feature | |
579 | ||
850b7ec9 | 580 | C<use feature 'unicode_strings'> tells the compiler to use Unicode rules |
69bcf1d3 FC |
581 | in all string operations executed within its scope (unless they are also |
582 | within the scope of either C<use locale> or C<use bytes>). The same applies | |
583 | to all regular expressions compiled within the scope, even if executed outside | |
2269d15c KW |
584 | it. It does not change the internal representation of strings, but only how |
585 | they are interpreted. | |
69bcf1d3 FC |
586 | |
587 | C<no feature 'unicode_strings'> tells the compiler to use the traditional | |
850b7ec9 | 588 | Perl rules wherein the native character set rules is used unless it is |
69bcf1d3 FC |
589 | clear to Perl that Unicode is desired. This can lead to some surprises |
590 | when the behavior suddenly changes. (See | |
591 | L<perlunicode/The "Unicode Bug"> for details.) For this reason, if you are | |
592 | potentially using Unicode in your program, the | |
593 | C<use feature 'unicode_strings'> subpragma is B<strongly> recommended. | |
594 | ||
2e2b2571 | 595 | This feature is available starting with Perl 5.12; was almost fully |
d6c970c7 | 596 | implemented in Perl 5.14; and extended in Perl 5.16 to cover C<quotemeta>; |
20ae58f7 AC |
597 | was extended further in Perl 5.26 to cover L<the range |
598 | operator|perlop/Range Operators>; and was extended again in Perl 5.28 to | |
599 | cover L<special-cased whitespace splitting|perlfunc/split>. | |
69bcf1d3 FC |
600 | |
601 | =head2 The 'unicode_eval' and 'evalbytes' features | |
602 | ||
9891e9b7 KW |
603 | Together, these two features are intended to replace the legacy string |
604 | C<eval> function, which behaves problematically in some instances. They are | |
605 | available starting with Perl 5.16, and are enabled by default by a | |
606 | S<C<use 5.16>> or higher declaration. | |
607 | ||
608 | C<unicode_eval> changes the behavior of plain string C<eval> to work more | |
609 | consistently, especially in the Unicode world. Certain (mis)behaviors | |
610 | couldn't be changed without breaking some things that had come to rely on | |
611 | them, so the feature can be enabled and disabled. Details are at | |
612 | L<perlfunc/Under the "unicode_eval" feature>. | |
613 | ||
614 | C<evalbytes> is like string C<eval>, but operating on a byte stream that is | |
615 | not UTF-8 encoded. Details are at L<perlfunc/evalbytes EXPR>. Without a | |
616 | S<C<use feature 'evalbytes'>> nor a S<C<use v5.16>> (or higher) declaration in | |
617 | the current scope, you can still access it by instead writing | |
618 | C<CORE::evalbytes>. | |
69bcf1d3 FC |
619 | |
620 | =head2 The 'current_sub' feature | |
621 | ||
622 | This provides the C<__SUB__> token that returns a reference to the current | |
623 | subroutine or C<undef> outside of a subroutine. | |
624 | ||
625 | This feature is available starting with Perl 5.16. | |
626 | ||
627 | =head2 The 'array_base' feature | |
628 | ||
c22e17d0 DIM |
629 | This feature supported the legacy C<$[> variable. See L<perlvar/$[>. |
630 | It was on by default but disabled under C<use v5.16> (see | |
631 | L</IMPLICIT LOADING>, below) and unavailable since perl 5.30. | |
69bcf1d3 FC |
632 | |
633 | This feature is available under this name starting with Perl 5.16. In | |
634 | previous versions, it was simply on all the time, and this pragma knew | |
635 | nothing about it. | |
636 | ||
2a4315f8 BF |
637 | =head2 The 'fc' feature |
638 | ||
639 | C<use feature 'fc'> tells the compiler to enable the C<fc> function, | |
640 | which implements Unicode casefolding. | |
641 | ||
642 | See L<perlfunc/fc> for details. | |
643 | ||
644 | This feature is available from Perl 5.16 onwards. | |
645 | ||
ca40957e FC |
646 | =head2 The 'lexical_subs' feature |
647 | ||
8f7d85af FC |
648 | In Perl versions prior to 5.26, this feature enabled |
649 | declaration of subroutines via C<my sub foo>, C<state sub foo> | |
650 | and C<our sub foo> syntax. See L<perlsub/Lexical Subroutines> for details. | |
ca40957e | 651 | |
8f7d85af FC |
652 | This feature is available from Perl 5.18 onwards. From Perl 5.18 to 5.24, |
653 | it was classed as experimental, and Perl emitted a warning for its | |
654 | usage, except when explicitly disabled: | |
ca40957e | 655 | |
8f7d85af | 656 | no warnings "experimental::lexical_subs"; |
ca40957e | 657 | |
8f7d85af FC |
658 | As of Perl 5.26, use of this feature no longer triggers a warning, though |
659 | the C<experimental::lexical_subs> warning category still exists (for | |
660 | compatibility with code that disables it). In addition, this syntax is | |
661 | not only no longer experimental, but it is enabled for all Perl code, | |
662 | regardless of what feature declarations are in scope. | |
ca40957e | 663 | |
f86d720e RS |
664 | =head2 The 'postderef' and 'postderef_qq' features |
665 | ||
1c2511e0 AC |
666 | The 'postderef_qq' feature extends the applicability of L<postfix |
667 | dereference syntax|perlref/Postfix Dereference Syntax> so that postfix array | |
668 | and scalar dereference are available in double-quotish interpolations. For | |
669 | example, it makes the following two statements equivalent: | |
f86d720e | 670 | |
1c2511e0 AC |
671 | my $s = "[@{ $h->{a} }]"; |
672 | my $s = "[$h->{a}->@*]"; | |
f86d720e | 673 | |
1c2511e0 AC |
674 | This feature is available from Perl 5.20 onwards. In Perl 5.20 and 5.22, it |
675 | was classed as experimental, and Perl emitted a warning for its | |
2ad792cd AC |
676 | usage, except when explicitly disabled: |
677 | ||
678 | no warnings "experimental::postderef"; | |
679 | ||
1c2511e0 | 680 | As of Perl 5.24, use of this feature no longer triggers a warning, though |
2ad792cd AC |
681 | the C<experimental::postderef> warning category still exists (for |
682 | compatibility with code that disables it). | |
f86d720e | 683 | |
1c2511e0 AC |
684 | The 'postderef' feature was used in Perl 5.20 and Perl 5.22 to enable |
685 | postfix dereference syntax outside double-quotish interpolations. In those | |
686 | versions, using it triggered the C<experimental::postderef> warning in the | |
687 | same way as the 'postderef_qq' feature did. As of Perl 5.24, this syntax is | |
688 | not only no longer experimental, but it is enabled for all Perl code, | |
689 | regardless of what feature declarations are in scope. | |
690 | ||
30d9c59b Z |
691 | =head2 The 'signatures' feature |
692 | ||
693 | B<WARNING>: This feature is still experimental and the implementation may | |
694 | change in future versions of Perl. For this reason, Perl will | |
695 | warn when you use the feature, unless you have explicitly disabled the | |
696 | warning: | |
697 | ||
698 | no warnings "experimental::signatures"; | |
699 | ||
700 | This enables unpacking of subroutine arguments into lexical variables | |
701 | by syntax such as | |
702 | ||
703 | sub foo ($left, $right) { | |
704 | return $left + $right; | |
705 | } | |
706 | ||
707 | See L<perlsub/Signatures> for details. | |
708 | ||
709 | This feature is available from Perl 5.20 onwards. | |
710 | ||
baabe3fb | 711 | =head2 The 'refaliasing' feature |
82848c10 FC |
712 | |
713 | B<WARNING>: This feature is still experimental and the implementation may | |
714 | change in future versions of Perl. For this reason, Perl will | |
715 | warn when you use the feature, unless you have explicitly disabled the | |
716 | warning: | |
717 | ||
baabe3fb | 718 | no warnings "experimental::refaliasing"; |
82848c10 FC |
719 | |
720 | This enables aliasing via assignment to references: | |
721 | ||
722 | \$a = \$b; # $a and $b now point to the same scalar | |
723 | \@a = \@b; # to the same array | |
724 | \%a = \%b; | |
725 | \&a = \&b; | |
726 | foreach \%hash (@array_of_hash_refs) { | |
727 | ... | |
728 | } | |
729 | ||
730 | See L<perlref/Assigning to References> for details. | |
731 | ||
732 | This feature is available from Perl 5.22 onwards. | |
733 | ||
70ea8edf FC |
734 | =head2 The 'bitwise' feature |
735 | ||
70ea8edf FC |
736 | This makes the four standard bitwise operators (C<& | ^ ~>) treat their |
737 | operands consistently as numbers, and introduces four new dotted operators | |
738 | (C<&. |. ^. ~.>) that treat their operands consistently as strings. The | |
739 | same applies to the assignment variants (C<&= |= ^= &.= |.= ^.=>). | |
740 | ||
741 | See L<perlop/Bitwise String Operators> for details. | |
742 | ||
193789ac FC |
743 | This feature is available from Perl 5.22 onwards. Starting in Perl 5.28, |
744 | C<use v5.28> will enable the feature. Before 5.28, it was still | |
745 | experimental and would emit a warning in the "experimental::bitwise" | |
746 | category. | |
70ea8edf | 747 | |
5c703779 FC |
748 | =head2 The 'declared_refs' feature |
749 | ||
750 | B<WARNING>: This feature is still experimental and the implementation may | |
751 | change in future versions of Perl. For this reason, Perl will | |
752 | warn when you use the feature, unless you have explicitly disabled the | |
753 | warning: | |
754 | ||
755 | no warnings "experimental::declared_refs"; | |
756 | ||
757 | This allows a reference to a variable to be declared with C<my>, C<state>, | |
758 | our C<our>, or localized with C<local>. It is intended mainly for use in | |
759 | conjunction with the "refaliasing" feature. See L<perlref/Declaring a | |
760 | Reference to a Variable> for examples. | |
761 | ||
762 | This feature is available from Perl 5.26 onwards. | |
763 | ||
813e85a0 PE |
764 | =head2 The 'isa' feature |
765 | ||
766 | This allows the use of the C<isa> infix operator, which tests whether the | |
767 | scalar given by the left operand is an object of the class given by the | |
768 | right operand. See L<perlop/Class Instance Operator> for more details. | |
769 | ||
770 | This feature is available from Perl 5.32 onwards. | |
771 | ||
0b657b19 DIM |
772 | =head2 The 'indirect' feature |
773 | ||
774 | This feature allows the use of L<indirect object | |
775 | syntax|perlobj/Indirect Object Syntax> for method calls, e.g. C<new | |
776 | Foo 1, 2;>. It is enabled by default, but can be turned off to | |
777 | disallow indirect object syntax. | |
778 | ||
779 | This feature is available under this name from Perl 5.32 onwards. In | |
780 | previous versions, it was simply on all the time. To disallow (or | |
781 | warn on) indirect object syntax on older Perls, see the L<indirect> | |
782 | CPAN module. | |
783 | ||
1ad5a39c TC |
784 | =head2 The 'multidimensional' feature |
785 | ||
786 | This feature enables multidimensional array emulation, a perl 4 (or | |
787 | earlier) feature that was used to emulate multidimensional arrays with | |
788 | hashes. This works by converting code like C<< $foo{$x, y} >> into | |
789 | C<< $foo{join($;, $x, $y} >>. It is enabled by default, but can be | |
790 | turned off to disable multidimensional array emulation. | |
791 | ||
792 | When this feature is disabled the syntax that is normally replaced | |
793 | will report a compilation error. | |
794 | ||
795 | This feature is available under this name from Perl 5.34 onwards. In | |
796 | previous versions, it was simply on all the time. | |
797 | ||
798 | You can use the L<multidimensional> module on CPAN to disable | |
799 | multidimensional array emulation for older versions of Perl. | |
800 | ||
69bcf1d3 FC |
801 | =head1 FEATURE BUNDLES |
802 | ||
803 | It's possible to load multiple features together, using | |
804 | a I<feature bundle>. The name of a feature bundle is prefixed with | |
805 | a colon, to distinguish it from an actual feature. | |
806 | ||
807 | use feature ":5.10"; | |
808 | ||
809 | The following feature bundles are available: | |
810 | ||
811 | bundle features included | |
812 | --------- ----------------- | |
2b3fe414 | 813 | PODTURES |
69bcf1d3 FC |
814 | The C<:default> bundle represents the feature set that is enabled before |
815 | any C<use feature> or C<no feature> declaration. | |
816 | ||
817 | Specifying sub-versions such as the C<0> in C<5.14.0> in feature bundles has | |
818 | no effect. Feature bundles are guaranteed to be the same for all sub-versions. | |
819 | ||
820 | use feature ":5.14.0"; # same as ":5.14" | |
821 | use feature ":5.14.1"; # same as ":5.14" | |
822 | ||
823 | =head1 IMPLICIT LOADING | |
824 | ||
825 | Instead of loading feature bundles by name, it is easier to let Perl do | |
826 | implicit loading of a feature bundle for you. | |
827 | ||
828 | There are two ways to load the C<feature> pragma implicitly: | |
829 | ||
830 | =over 4 | |
831 | ||
832 | =item * | |
833 | ||
834 | By using the C<-E> switch on the Perl command-line instead of C<-e>. | |
835 | That will enable the feature bundle for that version of Perl in the | |
836 | main compilation unit (that is, the one-liner that follows C<-E>). | |
837 | ||
838 | =item * | |
839 | ||
840 | By explicitly requiring a minimum Perl version number for your program, with | |
841 | the C<use VERSION> construct. That is, | |
842 | ||
843 | use v5.10.0; | |
844 | ||
845 | will do an implicit | |
846 | ||
39ec54a5 | 847 | no feature ':all'; |
69bcf1d3 FC |
848 | use feature ':5.10'; |
849 | ||
850 | and so on. Note how the trailing sub-version | |
851 | is automatically stripped from the | |
852 | version. | |
853 | ||
854 | But to avoid portability warnings (see L<perlfunc/use>), you may prefer: | |
855 | ||
856 | use 5.010; | |
857 | ||
858 | with the same effect. | |
859 | ||
860 | If the required version is older than Perl 5.10, the ":default" feature | |
861 | bundle is automatically loaded instead. | |
862 | ||
affe54fa AC |
863 | Unlike C<use feature ":5.12">, saying C<use v5.12> (or any higher version) |
864 | also does the equivalent of C<use strict>; see L<perlfunc/use> for details. | |
865 | ||
69bcf1d3 FC |
866 | =back |
867 | ||
868 | =cut | |
869 | ||
870 | sub import { | |
22055af9 | 871 | shift; |
36143a0c NC |
872 | |
873 | if (!@_) { | |
69bcf1d3 FC |
874 | croak("No features specified"); |
875 | } | |
36143a0c | 876 | |
d3757264 | 877 | __common(1, @_); |
69bcf1d3 FC |
878 | } |
879 | ||
880 | sub unimport { | |
22055af9 | 881 | shift; |
69bcf1d3 | 882 | |
39ec54a5 | 883 | # A bare C<no feature> should reset to the default bundle |
69bcf1d3 | 884 | if (!@_) { |
39ec54a5 RS |
885 | $^H &= ~($hint_uni8bit|$hint_mask); |
886 | return; | |
69bcf1d3 FC |
887 | } |
888 | ||
d3757264 NC |
889 | __common(0, @_); |
890 | } | |
891 | ||
892 | ||
893 | sub __common { | |
894 | my $import = shift; | |
0c8d5017 NC |
895 | my $bundle_number = $^H & $hint_mask; |
896 | my $features = $bundle_number != $hint_mask | |
9f601cf3 | 897 | && $feature_bundle{$hint_bundles[$bundle_number >> $hint_shift]}; |
0c8d5017 | 898 | if ($features) { |
da5b5421 | 899 | # Features are enabled implicitly via bundle hints. |
d9ee6ccb NC |
900 | # Delete any keys that may be left over from last time. |
901 | delete @^H{ values(%feature) }; | |
902 | $^H |= $hint_mask; | |
903 | for (@$features) { | |
904 | $^H{$feature{$_}} = 1; | |
905 | $^H |= $hint_uni8bit if $_ eq 'unicode_strings'; | |
906 | } | |
da5b5421 | 907 | } |
69bcf1d3 FC |
908 | while (@_) { |
909 | my $name = shift; | |
910 | if (substr($name, 0, 1) eq ":") { | |
911 | my $v = substr($name, 1); | |
912 | if (!exists $feature_bundle{$v}) { | |
913 | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; | |
914 | if (!exists $feature_bundle{$v}) { | |
915 | unknown_feature_bundle(substr($name, 1)); | |
916 | } | |
917 | } | |
918 | unshift @_, @{$feature_bundle{$v}}; | |
919 | next; | |
920 | } | |
36143a0c | 921 | if (!exists $feature{$name}) { |
db629560 FC |
922 | if (exists $noops{$name}) { |
923 | next; | |
924 | } | |
c22e17d0 DIM |
925 | if (!$import && exists $removed{$name}) { |
926 | next; | |
927 | } | |
69bcf1d3 | 928 | unknown_feature($name); |
69bcf1d3 | 929 | } |
d3757264 NC |
930 | if ($import) { |
931 | $^H{$feature{$name}} = 1; | |
932 | $^H |= $hint_uni8bit if $name eq 'unicode_strings'; | |
933 | } else { | |
69bcf1d3 FC |
934 | delete $^H{$feature{$name}}; |
935 | $^H &= ~ $hint_uni8bit if $name eq 'unicode_strings'; | |
936 | } | |
937 | } | |
938 | } | |
939 | ||
940 | sub unknown_feature { | |
941 | my $feature = shift; | |
942 | croak(sprintf('Feature "%s" is not supported by Perl %vd', | |
943 | $feature, $^V)); | |
944 | } | |
945 | ||
946 | sub unknown_feature_bundle { | |
947 | my $feature = shift; | |
948 | croak(sprintf('Feature bundle "%s" is not supported by Perl %vd', | |
949 | $feature, $^V)); | |
950 | } | |
951 | ||
952 | sub croak { | |
953 | require Carp; | |
954 | Carp::croak(@_); | |
955 | } | |
956 | ||
957 | 1; |