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Fix a couple of typos and standardize on using 'regexp' instead of
[perl5.git] / ext / re / re.pm
CommitLineData
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1package re;
2
99cc5cc6 3# pragma for controlling the regexp engine
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4use strict;
5use warnings;
6
ec781434 7our $VERSION = "0.10";
de8c5301 8our @ISA = qw(Exporter);
ec781434 9our @EXPORT_OK = ('regmust',
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10 qw(is_regexp regexp_pattern
11 regname regnames regnames_count));
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12our %EXPORT_OK = map { $_ => 1 } @EXPORT_OK;
13
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14my %bitmask = (
15 taint => 0x00100000, # HINT_RE_TAINT
16 eval => 0x00200000, # HINT_RE_EVAL
17);
18
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19sub setcolor {
20 eval { # Ignore errors
21 require Term::Cap;
22
23 my $terminal = Tgetent Term::Cap ({OSPEED => 9600}); # Avoid warning.
24 my $props = $ENV{PERL_RE_TC} || 'md,me,so,se,us,ue';
25 my @props = split /,/, $props;
26 my $colors = join "\t", map {$terminal->Tputs($_,1)} @props;
27
28 $colors =~ s/\0//g;
29 $ENV{PERL_RE_COLORS} = $colors;
30 };
31 if ($@) {
32 $ENV{PERL_RE_COLORS} ||= qq'\t\t> <\t> <\t\t';
33 }
34
35}
36
37my %flags = (
38 COMPILE => 0x0000FF,
39 PARSE => 0x000001,
40 OPTIMISE => 0x000002,
41 TRIEC => 0x000004,
42 DUMP => 0x000008,
f7819f85 43 FLAGS => 0x000010,
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44
45 EXECUTE => 0x00FF00,
46 INTUIT => 0x000100,
47 MATCH => 0x000200,
48 TRIEE => 0x000400,
49
50 EXTRA => 0xFF0000,
51 TRIEM => 0x010000,
52 OFFSETS => 0x020000,
53 OFFSETSDBG => 0x040000,
54 STATE => 0x080000,
55 OPTIMISEM => 0x100000,
56 STACK => 0x280000,
e7707071 57 BUFFERS => 0x400000,
2c296965 58 GPOS => 0x800000,
de8c5301 59);
e7707071 60$flags{ALL} = -1 & ~($flags{OFFSETS}|$flags{OFFSETSDBG}|$flags{BUFFERS});
de8c5301 61$flags{All} = $flags{all} = $flags{DUMP} | $flags{EXECUTE};
2c296965 62$flags{Extra} = $flags{EXECUTE} | $flags{COMPILE} | $flags{GPOS};
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63$flags{More} = $flags{MORE} = $flags{All} | $flags{TRIEC} | $flags{TRIEM} | $flags{STATE};
64$flags{State} = $flags{DUMP} | $flags{EXECUTE} | $flags{STATE};
65$flags{TRIE} = $flags{DUMP} | $flags{EXECUTE} | $flags{TRIEC};
66
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67if (defined &DynaLoader::boot_DynaLoader) {
68 require XSLoader;
69 XSLoader::load( __PACKAGE__, $VERSION);
de8c5301 70}
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71# else we're miniperl
72# We need to work for miniperl, because the XS toolchain uses Text::Wrap, which
73# uses re 'taint'.
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74
75sub _load_unload {
76 my ($on)= @_;
77 if ($on) {
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78 # We call install() every time, as if we didn't, we wouldn't
79 # "see" any changes to the color environment var since
80 # the last time it was called.
81
82 # install() returns an integer, which if casted properly
99cc5cc6 83 # in C resolves to a structure containing the regexp
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84 # hooks. Setting it to a random integer will guarantee
85 # segfaults.
86 $^H{regcomp} = install();
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87 } else {
88 delete $^H{regcomp};
89 }
90}
91
92sub bits {
93 my $on = shift;
94 my $bits = 0;
95 unless (@_) {
96 require Carp;
97 Carp::carp("Useless use of \"re\" pragma");
98 }
99 foreach my $idx (0..$#_){
100 my $s=$_[$idx];
101 if ($s eq 'Debug' or $s eq 'Debugcolor') {
102 setcolor() if $s =~/color/i;
103 ${^RE_DEBUG_FLAGS} = 0 unless defined ${^RE_DEBUG_FLAGS};
104 for my $idx ($idx+1..$#_) {
105 if ($flags{$_[$idx]}) {
106 if ($on) {
107 ${^RE_DEBUG_FLAGS} |= $flags{$_[$idx]};
108 } else {
109 ${^RE_DEBUG_FLAGS} &= ~ $flags{$_[$idx]};
110 }
111 } else {
112 require Carp;
113 Carp::carp("Unknown \"re\" Debug flag '$_[$idx]', possible flags: ",
114 join(", ",sort keys %flags ) );
115 }
116 }
117 _load_unload($on ? 1 : ${^RE_DEBUG_FLAGS});
118 last;
119 } elsif ($s eq 'debug' or $s eq 'debugcolor') {
120 setcolor() if $s =~/color/i;
121 _load_unload($on);
66e6b4c5 122 last;
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123 } elsif (exists $bitmask{$s}) {
124 $bits |= $bitmask{$s};
125 } elsif ($EXPORT_OK{$s}) {
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126 require Exporter;
127 re->export_to_level(2, 're', $s);
128 } else {
129 require Carp;
130 Carp::carp("Unknown \"re\" subpragma '$s' (known ones are: ",
131 join(', ', map {qq('$_')} 'debug', 'debugcolor', sort keys %bitmask),
132 ")");
133 }
134 }
135 $bits;
136}
137
138sub import {
139 shift;
140 $^H |= bits(1, @_);
141}
142
143sub unimport {
144 shift;
145 $^H &= ~ bits(0, @_);
146}
147
1481;
149
150__END__
56953603 151
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152=head1 NAME
153
154re - Perl pragma to alter regular expression behaviour
155
156=head1 SYNOPSIS
157
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158 use re 'taint';
159 ($x) = ($^X =~ /^(.*)$/s); # $x is tainted here
b3eb6a9b 160
2cd61cdb 161 $pat = '(?{ $foo = 1 })';
e4d48cc9 162 use re 'eval';
2cd61cdb 163 /foo${pat}bar/; # won't fail (when not under -T switch)
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164
165 {
166 no re 'taint'; # the default
167 ($x) = ($^X =~ /^(.*)$/s); # $x is not tainted here
168
169 no re 'eval'; # the default
2cd61cdb 170 /foo${pat}bar/; # disallowed (with or without -T switch)
e4d48cc9 171 }
b3eb6a9b 172
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173 use re 'debug'; # output debugging info during
174 /^(.*)$/s; # compile and run time
175
2cd61cdb 176
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177 use re 'debugcolor'; # same as 'debug', but with colored output
178 ...
179
a3621e74 180 use re qw(Debug All); # Finer tuned debugging options.
4ee9a43f 181 use re qw(Debug More);
fe759410 182 no re qw(Debug ALL); # Turn of all re debugging in this scope
4ee9a43f 183
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184 use re qw(is_regexp regexp_pattern); # import utility functions
185 my ($pat,$mods)=regexp_pattern(qr/foo/i);
186 if (is_regexp($obj)) {
187 print "Got regexp: ",
188 scalar regexp_pattern($obj); # just as perl would stringify it
189 } # but no hassle with blessed re's.
a3621e74 190
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191(We use $^X in these examples because it's tainted by default.)
192
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193=head1 DESCRIPTION
194
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195=head2 'taint' mode
196
b3eb6a9b 197When C<use re 'taint'> is in effect, and a tainted string is the target
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198of a regexp, the regexp memories (or values returned by the m// operator
199in list context) are tainted. This feature is useful when regexp operations
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200on tainted data aren't meant to extract safe substrings, but to perform
201other transformations.
b3eb6a9b 202
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203=head2 'eval' mode
204
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205When C<use re 'eval'> is in effect, a regexp is allowed to contain
206C<(?{ ... })> zero-width assertions even if the regular expression contains
ffbc6a93 207variable interpolation. That is normally disallowed, since it is a
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208potential security risk. Note that this pragma is ignored when the regular
209expression is obtained from tainted data, i.e. evaluation is always
3c4b39be 210disallowed with tainted regular expressions. See L<perlre/(?{ code })>.
2cd61cdb 211
ffbc6a93 212For the purpose of this pragma, interpolation of precompiled regular
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213expressions (i.e., the result of C<qr//>) is I<not> considered variable
214interpolation. Thus:
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215
216 /foo${pat}bar/
217
ffbc6a93 218I<is> allowed if $pat is a precompiled regular expression, even
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219if $pat contains C<(?{ ... })> assertions.
220
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221=head2 'debug' mode
222
ffbc6a93 223When C<use re 'debug'> is in effect, perl emits debugging messages when
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224compiling and using regular expressions. The output is the same as that
225obtained by running a C<-DDEBUGGING>-enabled perl interpreter with the
226B<-Dr> switch. It may be quite voluminous depending on the complexity
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227of the match. Using C<debugcolor> instead of C<debug> enables a
228form of output that can be used to get a colorful display on terminals
229that understand termcap color sequences. Set C<$ENV{PERL_RE_TC}> to a
230comma-separated list of C<termcap> properties to use for highlighting
ffbc6a93 231strings on/off, pre-point part on/off.
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232See L<perldebug/"Debugging regular expressions"> for additional info.
233
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234As of 5.9.5 the directive C<use re 'debug'> and its equivalents are
235lexically scoped, as the other directives are. However they have both
236compile-time and run-time effects.
237
238See L<perlmodlib/Pragmatic Modules>.
239
240=head2 'Debug' mode
241
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242Similarly C<use re 'Debug'> produces debugging output, the difference
243being that it allows the fine tuning of what debugging output will be
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244emitted. Options are divided into three groups, those related to
245compilation, those related to execution and those related to special
246purposes. The options are as follows:
247
248=over 4
249
250=item Compile related options
251
252=over 4
253
254=item COMPILE
255
256Turns on all compile related debug options.
257
258=item PARSE
259
260Turns on debug output related to the process of parsing the pattern.
261
262=item OPTIMISE
263
264Enables output related to the optimisation phase of compilation.
265
24b23f37 266=item TRIEC
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267
268Detailed info about trie compilation.
269
270=item DUMP
271
272Dump the final program out after it is compiled and optimised.
273
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274=back
275
276=item Execute related options
277
278=over 4
279
280=item EXECUTE
281
282Turns on all execute related debug options.
283
284=item MATCH
285
286Turns on debugging of the main matching loop.
287
24b23f37 288=item TRIEE
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289
290Extra debugging of how tries execute.
291
292=item INTUIT
293
294Enable debugging of start point optimisations.
295
296=back
297
298=item Extra debugging options
299
300=over 4
301
302=item EXTRA
303
304Turns on all "extra" debugging options.
305
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306=item BUFFERS
307
308Enable debugging the capture buffer storage during match. Warning,
309this can potentially produce extremely large output.
310
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311=item TRIEM
312
313Enable enhanced TRIE debugging. Enhances both TRIEE
314and TRIEC.
315
316=item STATE
317
4ee9a43f 318Enable debugging of states in the engine.
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319
320=item STACK
be8e71aa 321
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322Enable debugging of the recursion stack in the engine. Enabling
323or disabling this option automatically does the same for debugging
324states as well. This output from this can be quite large.
325
326=item OPTIMISEM
327
328Enable enhanced optimisation debugging and start point optimisations.
99cc5cc6 329Probably not useful except when debugging the regexp engine itself.
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330
331=item OFFSETS
332
333Dump offset information. This can be used to see how regops correlate
334to the pattern. Output format is
335
336 NODENUM:POSITION[LENGTH]
337
338Where 1 is the position of the first char in the string. Note that position
339can be 0, or larger than the actual length of the pattern, likewise length
340can be zero.
be8e71aa 341
24b23f37 342=item OFFSETSDBG
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343
344Enable debugging of offsets information. This emits copious
fe759410 345amounts of trace information and doesn't mesh well with other
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346debug options.
347
fe759410 348Almost definitely only useful to people hacking
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349on the offsets part of the debug engine.
350
351=back
352
353=item Other useful flags
354
355These are useful shortcuts to save on the typing.
356
357=over 4
358
359=item ALL
360
e7707071 361Enable all options at once except OFFSETS, OFFSETSDBG and BUFFERS
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362
363=item All
364
fe759410 365Enable DUMP and all execute options. Equivalent to:
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366
367 use re 'debug';
368
369=item MORE
370
371=item More
372
24b23f37 373Enable TRIEM and all execute compile and execute options.
be8e71aa 374
dba3f186 375=back
be8e71aa 376
dba3f186 377=back
a3621e74 378
1e2e3d02 379As of 5.9.5 the directive C<use re 'debug'> and its equivalents are
4ee9a43f 380lexically scoped, as the other directives are. However they have both
1e2e3d02 381compile-time and run-time effects.
b3eb6a9b 382
de8c5301 383=head2 Exportable Functions
b3eb6a9b 384
de8c5301 385As of perl 5.9.5 're' debug contains a number of utility functions that
4ee9a43f 386may be optionally exported into the caller's namespace. They are listed
de8c5301 387below.
b3eb6a9b 388
de8c5301 389=over 4
b3eb6a9b 390
de8c5301 391=item is_regexp($ref)
02ea72ae 392
de8c5301 393Returns true if the argument is a compiled regular expression as returned
4ee9a43f 394by C<qr//>, false if it is not.
02ea72ae 395
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396This function will not be confused by overloading or blessing. In
397internals terms, this extracts the regexp pointer out of the
de8c5301 398PERL_MAGIC_qr structure so it it cannot be fooled.
894be9b7 399
de8c5301 400=item regexp_pattern($ref)
02ea72ae 401
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402If the argument is a compiled regular expression as returned by C<qr//>,
403then this function returns the pattern.
be8e71aa 404
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405In list context it returns a two element list, the first element
406containing the pattern and the second containing the modifiers used when
407the pattern was compiled.
be8e71aa 408
4ee9a43f 409 my ($pat, $mods) = regexp_pattern($ref);
a3621e74 410
99cc5cc6 411In scalar context it returns the same as perl would when stringifying a raw
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412C<qr//> with the same pattern inside. If the argument is not a compiled
413reference then this routine returns false but defined in scalar context,
414and the empty list in list context. Thus the following
f9f4320a 415
de8c5301 416 if (regexp_pattern($ref) eq '(?i-xsm:foo)')
dba3f186 417
de8c5301 418will be warning free regardless of what $ref actually is.
380e0b81 419
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420Like C<is_regexp> this function will not be confused by overloading
421or blessing of the object.
b3eb6a9b 422
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423=item regmust($ref)
424
432acd5f 425If the argument is a compiled regular expression as returned by C<qr//>,
99cc5cc6 426then this function returns what the optimiser considers to be the longest
432acd5f
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427anchored fixed string and longest floating fixed string in the pattern.
428
429A I<fixed string> is defined as being a substring that must appear for the
430pattern to match. An I<anchored fixed string> is a fixed string that must
431appear at a particular offset from the beginning of the match. A I<floating
432fixed string> is defined as a fixed string that can appear at any point in
433a range of positions relative to the start of the match. For example,
434
435 my $qr = qr/here .* there/x;
436 my ($anchored, $floating) = regmust($qr);
256ddcd0 437 print "anchored:'$anchored'\nfloating:'$floating'\n";
432acd5f 438
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439results in
440
441 anchored:'here'
442 floating:'there'
443
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444Because the C<here> is before the C<.*> in the pattern, its position
445can be determined exactly. That's not true, however, for the C<there>;
446it could appear at any point after where the anchored string appeared.
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447Perl uses both for its optimisations, prefering the longer, or, if they are
448equal, the floating.
449
450B<NOTE:> This may not necessarily be the definitive longest anchored and
432acd5f 451floating string. This will be what the optimiser of the Perl that you
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452are using thinks is the longest. If you believe that the result is wrong
453please report it via the L<perlbug> utility.
454
28d8d7f4 455=item regname($name,$all)
44a2ac75 456
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457Returns the contents of a named buffer of the last successful match. If
458$all is true, then returns an array ref containing one entry per buffer,
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459otherwise returns the first defined buffer.
460
28d8d7f4 461=item regnames($all)
44a2ac75 462
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463Returns a list of all of the named buffers defined in the last successful
464match. If $all is true, then it returns all names defined, if not it returns
465only names which were involved in the match.
44a2ac75 466
28d8d7f4 467=item regnames_count()
44a2ac75 468
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469Returns the number of distinct names defined in the pattern used
470for the last successful match.
44a2ac75 471
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472B<Note:> this result is always the actual number of distinct
473named buffers defined, it may not actually match that which is
474returned by C<regnames()> and related routines when those routines
475have not been called with the $all parameter set.
44a2ac75 476
de8c5301 477=back
b3eb6a9b 478
de8c5301 479=head1 SEE ALSO
b3eb6a9b 480
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481L<perlmodlib/Pragmatic Modules>.
482
483=cut