Filename | /2home/ss5/perl5/perlbrew/perls/perl-5.12.3/lib/5.12.3/feature.pm |
Statements | Executed 656 statements in 1.32ms |
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25 | 25 | 25 | 987µs | 1.23ms | import | feature::
25 | 1 | 1 | 181µs | 181µs | CORE:subst (opcode) | feature::
50 | 1 | 1 | 62µs | 62µs | CORE:substcont (opcode) | feature::
0 | 0 | 0 | 0s | 0s | croak | feature::
0 | 0 | 0 | 0s | 0s | unimport | feature::
0 | 0 | 0 | 0s | 0s | unknown_feature | feature::
0 | 0 | 0 | 0s | 0s | unknown_feature_bundle | feature::
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1 | package feature; | ||||
2 | |||||
3 | 1 | 400ns | our $VERSION = '1.16'; | ||
4 | |||||
5 | # (feature name) => (internal name, used in %^H) | ||||
6 | 1 | 2µs | my %feature = ( | ||
7 | switch => 'feature_switch', | ||||
8 | say => "feature_say", | ||||
9 | state => "feature_state", | ||||
10 | unicode_strings => "feature_unicode", | ||||
11 | ); | ||||
12 | |||||
13 | # This gets set (for now) in $^H as well as in %^H, | ||||
14 | # for runtime speed of the uc/lc/ucfirst/lcfirst functions. | ||||
15 | # See HINT_UNI_8_BIT in perl.h. | ||||
16 | 1 | 200ns | our $hint_uni8bit = 0x00000800; | ||
17 | |||||
18 | # NB. the latest bundle must be loaded by the -E switch (see toke.c) | ||||
19 | |||||
20 | 1 | 4µs | my %feature_bundle = ( | ||
21 | "5.10" => [qw(switch say state)], | ||||
22 | "5.11" => [qw(switch say state unicode_strings)], | ||||
23 | "5.12" => [qw(switch say state unicode_strings)], | ||||
24 | ); | ||||
25 | |||||
26 | # special case | ||||
27 | 1 | 700ns | $feature_bundle{"5.9.5"} = $feature_bundle{"5.10"}; | ||
28 | |||||
29 | # TODO: | ||||
30 | # - think about versioned features (use feature switch => 2) | ||||
31 | |||||
32 | =head1 NAME | ||||
33 | |||||
34 | feature - Perl pragma to enable new features | ||||
35 | |||||
36 | =head1 SYNOPSIS | ||||
37 | |||||
38 | use feature qw(switch say); | ||||
39 | given ($foo) { | ||||
40 | when (1) { say "\$foo == 1" } | ||||
41 | when ([2,3]) { say "\$foo == 2 || \$foo == 3" } | ||||
42 | when (/^a[bc]d$/) { say "\$foo eq 'abd' || \$foo eq 'acd'" } | ||||
43 | when ($_ > 100) { say "\$foo > 100" } | ||||
44 | default { say "None of the above" } | ||||
45 | } | ||||
46 | |||||
47 | use feature ':5.10'; # loads all features available in perl 5.10 | ||||
48 | |||||
49 | =head1 DESCRIPTION | ||||
50 | |||||
51 | It is usually impossible to add new syntax to Perl without breaking | ||||
52 | some existing programs. This pragma provides a way to minimize that | ||||
53 | risk. New syntactic constructs, or new semantic meanings to older | ||||
54 | constructs, can be enabled by C<use feature 'foo'>, and will be parsed | ||||
55 | only when the appropriate feature pragma is in scope. | ||||
56 | |||||
57 | =head2 Lexical effect | ||||
58 | |||||
59 | Like other pragmas (C<use strict>, for example), features have a lexical | ||||
60 | effect. C<use feature qw(foo)> will only make the feature "foo" available | ||||
61 | from that point to the end of the enclosing block. | ||||
62 | |||||
63 | { | ||||
64 | use feature 'say'; | ||||
65 | say "say is available here"; | ||||
66 | } | ||||
67 | print "But not here.\n"; | ||||
68 | |||||
69 | =head2 C<no feature> | ||||
70 | |||||
71 | Features can also be turned off by using C<no feature "foo">. This too | ||||
72 | has lexical effect. | ||||
73 | |||||
74 | use feature 'say'; | ||||
75 | say "say is available here"; | ||||
76 | { | ||||
77 | no feature 'say'; | ||||
78 | print "But not here.\n"; | ||||
79 | } | ||||
80 | say "Yet it is here."; | ||||
81 | |||||
82 | C<no feature> with no features specified will turn off all features. | ||||
83 | |||||
84 | =head2 The 'switch' feature | ||||
85 | |||||
86 | C<use feature 'switch'> tells the compiler to enable the Perl 6 | ||||
87 | given/when construct. | ||||
88 | |||||
89 | See L<perlsyn/"Switch statements"> for details. | ||||
90 | |||||
91 | =head2 The 'say' feature | ||||
92 | |||||
93 | C<use feature 'say'> tells the compiler to enable the Perl 6 | ||||
94 | C<say> function. | ||||
95 | |||||
96 | See L<perlfunc/say> for details. | ||||
97 | |||||
98 | =head2 the 'state' feature | ||||
99 | |||||
100 | C<use feature 'state'> tells the compiler to enable C<state> | ||||
101 | variables. | ||||
102 | |||||
103 | See L<perlsub/"Persistent Private Variables"> for details. | ||||
104 | |||||
105 | =head2 the 'unicode_strings' feature | ||||
106 | |||||
107 | C<use feature 'unicode_strings'> tells the compiler to treat | ||||
108 | all strings outside of C<use locale> and C<use bytes> as Unicode. It is | ||||
109 | available starting with Perl 5.11.3. | ||||
110 | |||||
111 | See L<perlunicode/The "Unicode Bug"> for details. | ||||
112 | |||||
113 | =head1 FEATURE BUNDLES | ||||
114 | |||||
115 | It's possible to load a whole slew of features in one go, using | ||||
116 | a I<feature bundle>. The name of a feature bundle is prefixed with | ||||
117 | a colon, to distinguish it from an actual feature. At present, the | ||||
118 | only feature bundle is C<use feature ":5.10"> which is equivalent | ||||
119 | to C<use feature qw(switch say state)>. | ||||
120 | |||||
121 | Specifying sub-versions such as the C<0> in C<5.10.0> in feature bundles has | ||||
122 | no effect: feature bundles are guaranteed to be the same for all sub-versions. | ||||
123 | |||||
124 | =head1 IMPLICIT LOADING | ||||
125 | |||||
126 | There are two ways to load the C<feature> pragma implicitly : | ||||
127 | |||||
128 | =over 4 | ||||
129 | |||||
130 | =item * | ||||
131 | |||||
132 | By using the C<-E> switch on the command-line instead of C<-e>. It enables | ||||
133 | all available features in the main compilation unit (that is, the one-liner.) | ||||
134 | |||||
135 | =item * | ||||
136 | |||||
137 | By requiring explicitly a minimal Perl version number for your program, with | ||||
138 | the C<use VERSION> construct, and when the version is higher than or equal to | ||||
139 | 5.10.0. That is, | ||||
140 | |||||
141 | use 5.10.0; | ||||
142 | |||||
143 | will do an implicit | ||||
144 | |||||
145 | use feature ':5.10'; | ||||
146 | |||||
147 | and so on. Note how the trailing sub-version is automatically stripped from the | ||||
148 | version. | ||||
149 | |||||
150 | But to avoid portability warnings (see L<perlfunc/use>), you may prefer: | ||||
151 | |||||
152 | use 5.010; | ||||
153 | |||||
154 | with the same effect. | ||||
155 | |||||
156 | =back | ||||
157 | |||||
158 | =cut | ||||
159 | |||||
160 | # spent 1.23ms (987µs+243µs) within feature::import which was called 25 times, avg 49µs/call:
# once (86µs+21µs) by Tapper::MCP::Scheduler::PrioQueue::BEGIN@5.8 at line 5 of lib/Tapper/MCP/Scheduler/PrioQueue.pm
# once (77µs+7µs) by Tapper::Schema::TestrunDB::Result::Testrun::BEGIN@9.21 at line 9 of Tapper/Schema/TestrunDB/Result/Testrun.pm
# once (52µs+8µs) by Tapper::Schema::ReportsDB::Result::Tap::BEGIN@9.29 at line 9 of Tapper/Schema/ReportsDB/Result/Tap.pm
# once (52µs+7µs) by Tapper::Schema::ReportsDB::Result::View020TestrunOverview::BEGIN@10.30 at line 10 of Tapper/Schema/ReportsDB/Result/View020TestrunOverview.pm
# once (38µs+15µs) by Tapper::Schema::TestrunDB::BEGIN@6.17 at line 6 of Tapper/Schema/TestrunDB.pm
# once (36µs+15µs) by Tapper::MCP::Scheduler::Controller::BEGIN@5.1 at line 5 of lib/Tapper/MCP/Scheduler/Controller.pm
# once (36µs+13µs) by Tapper::Schema::TestrunDB::Result::Scenario::BEGIN@9.19 at line 9 of Tapper/Schema/TestrunDB/Result/Scenario.pm
# once (37µs+12µs) by Tapper::Schema::TestrunDB::ResultSet::Host::BEGIN@9.25 at line 9 of Tapper/Schema/TestrunDB/ResultSet/Host.pm
# once (36µs+13µs) by Tapper::Schema::ReportsDB::BEGIN@6.26 at line 6 of Tapper/Schema/ReportsDB.pm
# once (37µs+10µs) by Tapper::Schema::TestrunDB::ResultSet::TestrunScheduling::BEGIN@9.23 at line 9 of Tapper/Schema/TestrunDB/ResultSet/TestrunScheduling.pm
# once (33µs+12µs) by Tapper::Model::BEGIN@13.3 at line 13 of Tapper/Model.pm
# once (36µs+9µs) by Tapper::Schema::ReportsDB::Result::Report::BEGIN@9.32 at line 9 of Tapper/Schema/ReportsDB/Result/Report.pm
# once (36µs+8µs) by Tapper::Schema::ReportsDB::Result::View010TestrunOverviewReports::BEGIN@10.28 at line 10 of Tapper/Schema/ReportsDB/Result/View010TestrunOverviewReports.pm
# once (37µs+6µs) by Tapper::MCP::Net::TAP::BEGIN@3.13 at line 3 of lib/Tapper/MCP/Net/TAP.pm
# once (33µs+10µs) by Tapper::MCP::Scheduler::Algorithm::WFQ::BEGIN@6.16 at line 6 of lib/Tapper/MCP/Scheduler/Algorithm/WFQ.pm
# once (35µs+8µs) by Tapper::Schema::ReportsDB::Result::ReportgroupTestrun::BEGIN@9.27 at line 9 of Tapper/Schema/ReportsDB/Result/ReportgroupTestrun.pm
# once (33µs+9µs) by Tapper::Base::BEGIN@16.2 at line 16 of Tapper/Base.pm
# once (35µs+7µs) by Tapper::Schema::TestrunDB::Result::ScenarioElement::BEGIN@9.20 at line 9 of Tapper/Schema/TestrunDB/Result/ScenarioElement.pm
# once (33µs+9µs) by Tapper::Config::BEGIN@10.4 at line 10 of Tapper/Config.pm
# once (35µs+7µs) by Tapper::Schema::TestrunDB::Result::HostFeature::BEGIN@9.18 at line 9 of Tapper/Schema/TestrunDB/Result/HostFeature.pm
# once (34µs+7µs) by Tapper::Schema::TestrunDB::Result::Host::BEGIN@9.22 at line 9 of Tapper/Schema/TestrunDB/Result/Host.pm
# once (34µs+7µs) by Tapper::MCP::Net::BEGIN@7.9 at line 7 of lib/Tapper/MCP/Net.pm
# once (31µs+8µs) by Tapper::Schema::ReportsDB::Result::ReportgroupTestrunStats::BEGIN@9.31 at line 9 of Tapper/Schema/ReportsDB/Result/ReportgroupTestrunStats.pm
# once (31µs+9µs) by Tapper::MCP::Scheduler::Algorithm::BEGIN@5.5 at line 5 of lib/Tapper/MCP/Scheduler/Algorithm.pm
# once (22µs+4µs) by Tapper::Schema::TestrunDB::ResultSet::Queue::BEGIN@9.24 at line 9 of Tapper/Schema/TestrunDB/ResultSet/Queue.pm | ||||
161 | 75 | 176µs | my $class = shift; | ||
162 | if (@_ == 0) { | ||||
163 | croak("No features specified"); | ||||
164 | } | ||||
165 | while (@_) { | ||||
166 | 425 | 451µs | my $name = shift(@_); | ||
167 | 100 | 149µs | if (substr($name, 0, 1) eq ":") { | ||
168 | my $v = substr($name, 1); | ||||
169 | 50 | 530µs | if (!exists $feature_bundle{$v}) { | ||
170 | 75 | 243µs | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; # spent 181µs making 25 calls to feature::CORE:subst, avg 7µs/call
# spent 62µs making 50 calls to feature::CORE:substcont, avg 1µs/call | ||
171 | if (!exists $feature_bundle{$v}) { | ||||
172 | unknown_feature_bundle(substr($name, 1)); | ||||
173 | } | ||||
174 | } | ||||
175 | unshift @_, @{$feature_bundle{$v}}; | ||||
176 | next; | ||||
177 | } | ||||
178 | if (!exists $feature{$name}) { | ||||
179 | unknown_feature($name); | ||||
180 | } | ||||
181 | $^H{$feature{$name}} = 1; | ||||
182 | $^H |= $hint_uni8bit if $name eq 'unicode_strings'; | ||||
183 | } | ||||
184 | } | ||||
185 | |||||
186 | sub unimport { | ||||
187 | my $class = shift; | ||||
188 | |||||
189 | # A bare C<no feature> should disable *all* features | ||||
190 | if (!@_) { | ||||
191 | delete @^H{ values(%feature) }; | ||||
192 | $^H &= ~ $hint_uni8bit; | ||||
193 | return; | ||||
194 | } | ||||
195 | |||||
196 | while (@_) { | ||||
197 | my $name = shift; | ||||
198 | if (substr($name, 0, 1) eq ":") { | ||||
199 | my $v = substr($name, 1); | ||||
200 | if (!exists $feature_bundle{$v}) { | ||||
201 | $v =~ s/^([0-9]+)\.([0-9]+).[0-9]+$/$1.$2/; | ||||
202 | if (!exists $feature_bundle{$v}) { | ||||
203 | unknown_feature_bundle(substr($name, 1)); | ||||
204 | } | ||||
205 | } | ||||
206 | unshift @_, @{$feature_bundle{$v}}; | ||||
207 | next; | ||||
208 | } | ||||
209 | if (!exists($feature{$name})) { | ||||
210 | unknown_feature($name); | ||||
211 | } | ||||
212 | else { | ||||
213 | delete $^H{$feature{$name}}; | ||||
214 | $^H &= ~ $hint_uni8bit if $name eq 'unicode_strings'; | ||||
215 | } | ||||
216 | } | ||||
217 | } | ||||
218 | |||||
219 | sub unknown_feature { | ||||
220 | my $feature = shift; | ||||
221 | croak(sprintf('Feature "%s" is not supported by Perl %vd', | ||||
222 | $feature, $^V)); | ||||
223 | } | ||||
224 | |||||
225 | sub unknown_feature_bundle { | ||||
226 | my $feature = shift; | ||||
227 | croak(sprintf('Feature bundle "%s" is not supported by Perl %vd', | ||||
228 | $feature, $^V)); | ||||
229 | } | ||||
230 | |||||
231 | sub croak { | ||||
232 | require Carp; | ||||
233 | Carp::croak(@_); | ||||
234 | } | ||||
235 | |||||
236 | 1 | 6µs | 1; | ||
# spent 181µs within feature::CORE:subst which was called 25 times, avg 7µs/call:
# 25 times (181µs+0s) by feature::import at line 170, avg 7µs/call | |||||
# spent 62µs within feature::CORE:substcont which was called 50 times, avg 1µs/call:
# 50 times (62µs+0s) by feature::import at line 170, avg 1µs/call |