1package re; 2 3# pragma for controlling the regexp engine 4use strict; 5use warnings; 6 7our $VERSION = "0.26"; 8our @ISA = qw(Exporter); 9our @EXPORT_OK = ('regmust', 10 qw(is_regexp regexp_pattern 11 regname regnames regnames_count)); 12our %EXPORT_OK = map { $_ => 1 } @EXPORT_OK; 13 14my %bitmask = ( 15 taint => 0x00100000, # HINT_RE_TAINT 16 eval => 0x00200000, # HINT_RE_EVAL 17); 18 19my $flags_hint = 0x02000000; # HINT_RE_FLAGS 20my $PMMOD_SHIFT = 0; 21my %reflags = ( 22 m => 1 << ($PMMOD_SHIFT + 0), 23 s => 1 << ($PMMOD_SHIFT + 1), 24 i => 1 << ($PMMOD_SHIFT + 2), 25 x => 1 << ($PMMOD_SHIFT + 3), 26 p => 1 << ($PMMOD_SHIFT + 4), 27# special cases: 28 d => 0, 29 l => 1, 30 u => 2, 31 a => 3, 32 aa => 4, 33); 34 35sub setcolor { 36 eval { # Ignore errors 37 require Term::Cap; 38 39 my $terminal = Tgetent Term::Cap ({OSPEED => 9600}); # Avoid warning. 40 my $props = $ENV{PERL_RE_TC} || 'md,me,so,se,us,ue'; 41 my @props = split /,/, $props; 42 my $colors = join "\t", map {$terminal->Tputs($_,1)} @props; 43 44 $colors =~ s/\0//g; 45 $ENV{PERL_RE_COLORS} = $colors; 46 }; 47 if ($@) { 48 $ENV{PERL_RE_COLORS} ||= qq'\t\t> <\t> <\t\t'; 49 } 50 51} 52 53my %flags = ( 54 COMPILE => 0x0000FF, 55 PARSE => 0x000001, 56 OPTIMISE => 0x000002, 57 TRIEC => 0x000004, 58 DUMP => 0x000008, 59 FLAGS => 0x000010, 60 61 EXECUTE => 0x00FF00, 62 INTUIT => 0x000100, 63 MATCH => 0x000200, 64 TRIEE => 0x000400, 65 66 EXTRA => 0xFF0000, 67 TRIEM => 0x010000, 68 OFFSETS => 0x020000, 69 OFFSETSDBG => 0x040000, 70 STATE => 0x080000, 71 OPTIMISEM => 0x100000, 72 STACK => 0x280000, 73 BUFFERS => 0x400000, 74 GPOS => 0x800000, 75); 76$flags{ALL} = -1 & ~($flags{OFFSETS}|$flags{OFFSETSDBG}|$flags{BUFFERS}); 77$flags{All} = $flags{all} = $flags{DUMP} | $flags{EXECUTE}; 78$flags{Extra} = $flags{EXECUTE} | $flags{COMPILE} | $flags{GPOS}; 79$flags{More} = $flags{MORE} = $flags{All} | $flags{TRIEC} | $flags{TRIEM} | $flags{STATE}; 80$flags{State} = $flags{DUMP} | $flags{EXECUTE} | $flags{STATE}; 81$flags{TRIE} = $flags{DUMP} | $flags{EXECUTE} | $flags{TRIEC}; 82 83if (defined &DynaLoader::boot_DynaLoader) { 84 require XSLoader; 85 XSLoader::load(); 86} 87# else we're miniperl 88# We need to work for miniperl, because the XS toolchain uses Text::Wrap, which 89# uses re 'taint'. 90 91sub _load_unload { 92 my ($on)= @_; 93 if ($on) { 94 # We call install() every time, as if we didn't, we wouldn't 95 # "see" any changes to the color environment var since 96 # the last time it was called. 97 98 # install() returns an integer, which if casted properly 99 # in C resolves to a structure containing the regexp 100 # hooks. Setting it to a random integer will guarantee 101 # segfaults. 102 $^H{regcomp} = install(); 103 } else { 104 delete $^H{regcomp}; 105 } 106} 107 108sub bits { 109 my $on = shift; 110 my $bits = 0; 111 ARG: 112 foreach my $idx (0..$#_){ 113 my $s=$_[$idx]; 114 if ($s eq 'Debug' or $s eq 'Debugcolor') { 115 setcolor() if $s =~/color/i; 116 ${^RE_DEBUG_FLAGS} = 0 unless defined ${^RE_DEBUG_FLAGS}; 117 for my $idx ($idx+1..$#_) { 118 if ($flags{$_[$idx]}) { 119 if ($on) { 120 ${^RE_DEBUG_FLAGS} |= $flags{$_[$idx]}; 121 } else { 122 ${^RE_DEBUG_FLAGS} &= ~ $flags{$_[$idx]}; 123 } 124 } else { 125 require Carp; 126 Carp::carp("Unknown \"re\" Debug flag '$_[$idx]', possible flags: ", 127 join(", ",sort keys %flags ) ); 128 } 129 } 130 _load_unload($on ? 1 : ${^RE_DEBUG_FLAGS}); 131 last; 132 } elsif ($s eq 'debug' or $s eq 'debugcolor') { 133 setcolor() if $s =~/color/i; 134 _load_unload($on); 135 last; 136 } elsif (exists $bitmask{$s}) { 137 $bits |= $bitmask{$s}; 138 } elsif ($EXPORT_OK{$s}) { 139 require Exporter; 140 re->export_to_level(2, 're', $s); 141 } elsif ($s =~ s/^\///) { 142 my $reflags = $^H{reflags} || 0; 143 my $seen_charset; 144 while ($s =~ m/( . )/gx) { 145 local $_ = $1; 146 if (/[adul]/) { 147 # The 'a' may be repeated; hide this from the rest of the 148 # code by counting and getting rid of all of them, then 149 # changing to 'aa' if there is a repeat. 150 if ($_ eq 'a') { 151 my $sav_pos = pos $s; 152 my $a_count = $s =~ s/a//g; 153 pos $s = $sav_pos - 1; # -1 because got rid of the 'a' 154 if ($a_count > 2) { 155 require Carp; 156 Carp::carp( 157 qq 'The "a" flag may only appear a maximum of twice' 158 ); 159 } 160 elsif ($a_count == 2) { 161 $_ = 'aa'; 162 } 163 } 164 if ($on) { 165 if ($seen_charset) { 166 require Carp; 167 if ($seen_charset ne $_) { 168 Carp::carp( 169 qq 'The "$seen_charset" and "$_" flags ' 170 .qq 'are exclusive' 171 ); 172 } 173 else { 174 Carp::carp( 175 qq 'The "$seen_charset" flag may not appear ' 176 .qq 'twice' 177 ); 178 } 179 } 180 $^H{reflags_charset} = $reflags{$_}; 181 $seen_charset = $_; 182 } 183 else { 184 delete $^H{reflags_charset} 185 if defined $^H{reflags_charset} 186 && $^H{reflags_charset} == $reflags{$_}; 187 } 188 } elsif (exists $reflags{$_}) { 189 $on 190 ? $reflags |= $reflags{$_} 191 : ($reflags &= ~$reflags{$_}); 192 } else { 193 require Carp; 194 Carp::carp( 195 qq'Unknown regular expression flag "$_"' 196 ); 197 next ARG; 198 } 199 } 200 ($^H{reflags} = $reflags or defined $^H{reflags_charset}) 201 ? $^H |= $flags_hint 202 : ($^H &= ~$flags_hint); 203 } else { 204 require Carp; 205 Carp::carp("Unknown \"re\" subpragma '$s' (known ones are: ", 206 join(', ', map {qq('$_')} 'debug', 'debugcolor', sort keys %bitmask), 207 ")"); 208 } 209 } 210 $bits; 211} 212 213sub import { 214 shift; 215 $^H |= bits(1, @_); 216} 217 218sub unimport { 219 shift; 220 $^H &= ~ bits(0, @_); 221} 222 2231; 224 225__END__ 226 227=head1 NAME 228 229re - Perl pragma to alter regular expression behaviour 230 231=head1 SYNOPSIS 232 233 use re 'taint'; 234 ($x) = ($^X =~ /^(.*)$/s); # $x is tainted here 235 236 $pat = '(?{ $foo = 1 })'; 237 use re 'eval'; 238 /foo${pat}bar/; # won't fail (when not under -T 239 # switch) 240 241 { 242 no re 'taint'; # the default 243 ($x) = ($^X =~ /^(.*)$/s); # $x is not tainted here 244 245 no re 'eval'; # the default 246 /foo${pat}bar/; # disallowed (with or without -T 247 # switch) 248 } 249 250 use re '/ix'; 251 "FOO" =~ / foo /; # /ix implied 252 no re '/x'; 253 "FOO" =~ /foo/; # just /i implied 254 255 use re 'debug'; # output debugging info during 256 /^(.*)$/s; # compile and run time 257 258 259 use re 'debugcolor'; # same as 'debug', but with colored 260 # output 261 ... 262 263 use re qw(Debug All); # Same as "use re 'debug'", but you 264 # can use "Debug" with things other 265 # than 'All' 266 use re qw(Debug More); # 'All' plus output more details 267 no re qw(Debug ALL); # Turn on (almost) all re debugging 268 # in this scope 269 270 use re qw(is_regexp regexp_pattern); # import utility functions 271 my ($pat,$mods)=regexp_pattern(qr/foo/i); 272 if (is_regexp($obj)) { 273 print "Got regexp: ", 274 scalar regexp_pattern($obj); # just as perl would stringify 275 } # it but no hassle with blessed 276 # re's. 277 278(We use $^X in these examples because it's tainted by default.) 279 280=head1 DESCRIPTION 281 282=head2 'taint' mode 283 284When C<use re 'taint'> is in effect, and a tainted string is the target 285of a regexp, the regexp memories (or values returned by the m// operator 286in list context) are tainted. This feature is useful when regexp operations 287on tainted data aren't meant to extract safe substrings, but to perform 288other transformations. 289 290=head2 'eval' mode 291 292When C<use re 'eval'> is in effect, a regexp is allowed to contain 293C<(?{ ... })> zero-width assertions and C<(??{ ... })> postponed 294subexpressions that are derived from variable interpolation, rather than 295appearing literally within the regexp. That is normally disallowed, since 296it is a 297potential security risk. Note that this pragma is ignored when the regular 298expression is obtained from tainted data, i.e. evaluation is always 299disallowed with tainted regular expressions. See L<perlre/(?{ code })> 300and L<perlre/(??{ code })>. 301 302For the purpose of this pragma, interpolation of precompiled regular 303expressions (i.e., the result of C<qr//>) is I<not> considered variable 304interpolation. Thus: 305 306 /foo${pat}bar/ 307 308I<is> allowed if $pat is a precompiled regular expression, even 309if $pat contains C<(?{ ... })> assertions or C<(??{ ... })> subexpressions. 310 311=head2 '/flags' mode 312 313When C<use re '/flags'> is specified, the given flags are automatically 314added to every regular expression till the end of the lexical scope. 315 316C<no re '/flags'> will turn off the effect of C<use re '/flags'> for the 317given flags. 318 319For example, if you want all your regular expressions to have /msx on by 320default, simply put 321 322 use re '/msx'; 323 324at the top of your code. 325 326The character set /adul flags cancel each other out. So, in this example, 327 328 use re "/u"; 329 "ss" =~ /\xdf/; 330 use re "/d"; 331 "ss" =~ /\xdf/; 332 333the second C<use re> does an implicit C<no re '/u'>. 334 335Turning on one of the character set flags with C<use re> takes precedence over the 336C<locale> pragma and the 'unicode_strings' C<feature>, for regular 337expressions. Turning off one of these flags when it is active reverts to 338the behaviour specified by whatever other pragmata are in scope. For 339example: 340 341 use feature "unicode_strings"; 342 no re "/u"; # does nothing 343 use re "/l"; 344 no re "/l"; # reverts to unicode_strings behaviour 345 346=head2 'debug' mode 347 348When C<use re 'debug'> is in effect, perl emits debugging messages when 349compiling and using regular expressions. The output is the same as that 350obtained by running a C<-DDEBUGGING>-enabled perl interpreter with the 351B<-Dr> switch. It may be quite voluminous depending on the complexity 352of the match. Using C<debugcolor> instead of C<debug> enables a 353form of output that can be used to get a colorful display on terminals 354that understand termcap color sequences. Set C<$ENV{PERL_RE_TC}> to a 355comma-separated list of C<termcap> properties to use for highlighting 356strings on/off, pre-point part on/off. 357See L<perldebug/"Debugging Regular Expressions"> for additional info. 358 359As of 5.9.5 the directive C<use re 'debug'> and its equivalents are 360lexically scoped, as the other directives are. However they have both 361compile-time and run-time effects. 362 363See L<perlmodlib/Pragmatic Modules>. 364 365=head2 'Debug' mode 366 367Similarly C<use re 'Debug'> produces debugging output, the difference 368being that it allows the fine tuning of what debugging output will be 369emitted. Options are divided into three groups, those related to 370compilation, those related to execution and those related to special 371purposes. The options are as follows: 372 373=over 4 374 375=item Compile related options 376 377=over 4 378 379=item COMPILE 380 381Turns on all compile related debug options. 382 383=item PARSE 384 385Turns on debug output related to the process of parsing the pattern. 386 387=item OPTIMISE 388 389Enables output related to the optimisation phase of compilation. 390 391=item TRIEC 392 393Detailed info about trie compilation. 394 395=item DUMP 396 397Dump the final program out after it is compiled and optimised. 398 399=back 400 401=item Execute related options 402 403=over 4 404 405=item EXECUTE 406 407Turns on all execute related debug options. 408 409=item MATCH 410 411Turns on debugging of the main matching loop. 412 413=item TRIEE 414 415Extra debugging of how tries execute. 416 417=item INTUIT 418 419Enable debugging of start-point optimisations. 420 421=back 422 423=item Extra debugging options 424 425=over 4 426 427=item EXTRA 428 429Turns on all "extra" debugging options. 430 431=item BUFFERS 432 433Enable debugging the capture group storage during match. Warning, 434this can potentially produce extremely large output. 435 436=item TRIEM 437 438Enable enhanced TRIE debugging. Enhances both TRIEE 439and TRIEC. 440 441=item STATE 442 443Enable debugging of states in the engine. 444 445=item STACK 446 447Enable debugging of the recursion stack in the engine. Enabling 448or disabling this option automatically does the same for debugging 449states as well. This output from this can be quite large. 450 451=item OPTIMISEM 452 453Enable enhanced optimisation debugging and start-point optimisations. 454Probably not useful except when debugging the regexp engine itself. 455 456=item OFFSETS 457 458Dump offset information. This can be used to see how regops correlate 459to the pattern. Output format is 460 461 NODENUM:POSITION[LENGTH] 462 463Where 1 is the position of the first char in the string. Note that position 464can be 0, or larger than the actual length of the pattern, likewise length 465can be zero. 466 467=item OFFSETSDBG 468 469Enable debugging of offsets information. This emits copious 470amounts of trace information and doesn't mesh well with other 471debug options. 472 473Almost definitely only useful to people hacking 474on the offsets part of the debug engine. 475 476=back 477 478=item Other useful flags 479 480These are useful shortcuts to save on the typing. 481 482=over 4 483 484=item ALL 485 486Enable all options at once except OFFSETS, OFFSETSDBG and BUFFERS. 487(To get every single option without exception, use both ALL and EXTRA.) 488 489=item All 490 491Enable DUMP and all execute options. Equivalent to: 492 493 use re 'debug'; 494 495=item MORE 496 497=item More 498 499Enable the options enabled by "All", plus STATE, TRIEC, and TRIEM. 500 501=back 502 503=back 504 505As of 5.9.5 the directive C<use re 'debug'> and its equivalents are 506lexically scoped, as are the other directives. However they have both 507compile-time and run-time effects. 508 509=head2 Exportable Functions 510 511As of perl 5.9.5 're' debug contains a number of utility functions that 512may be optionally exported into the caller's namespace. They are listed 513below. 514 515=over 4 516 517=item is_regexp($ref) 518 519Returns true if the argument is a compiled regular expression as returned 520by C<qr//>, false if it is not. 521 522This function will not be confused by overloading or blessing. In 523internals terms, this extracts the regexp pointer out of the 524PERL_MAGIC_qr structure so it cannot be fooled. 525 526=item regexp_pattern($ref) 527 528If the argument is a compiled regular expression as returned by C<qr//>, 529then this function returns the pattern. 530 531In list context it returns a two element list, the first element 532containing the pattern and the second containing the modifiers used when 533the pattern was compiled. 534 535 my ($pat, $mods) = regexp_pattern($ref); 536 537In scalar context it returns the same as perl would when stringifying a raw 538C<qr//> with the same pattern inside. If the argument is not a compiled 539reference then this routine returns false but defined in scalar context, 540and the empty list in list context. Thus the following 541 542 if (regexp_pattern($ref) eq '(?^i:foo)') 543 544will be warning free regardless of what $ref actually is. 545 546Like C<is_regexp> this function will not be confused by overloading 547or blessing of the object. 548 549=item regmust($ref) 550 551If the argument is a compiled regular expression as returned by C<qr//>, 552then this function returns what the optimiser considers to be the longest 553anchored fixed string and longest floating fixed string in the pattern. 554 555A I<fixed string> is defined as being a substring that must appear for the 556pattern to match. An I<anchored fixed string> is a fixed string that must 557appear at a particular offset from the beginning of the match. A I<floating 558fixed string> is defined as a fixed string that can appear at any point in 559a range of positions relative to the start of the match. For example, 560 561 my $qr = qr/here .* there/x; 562 my ($anchored, $floating) = regmust($qr); 563 print "anchored:'$anchored'\nfloating:'$floating'\n"; 564 565results in 566 567 anchored:'here' 568 floating:'there' 569 570Because the C<here> is before the C<.*> in the pattern, its position 571can be determined exactly. That's not true, however, for the C<there>; 572it could appear at any point after where the anchored string appeared. 573Perl uses both for its optimisations, preferring the longer, or, if they are 574equal, the floating. 575 576B<NOTE:> This may not necessarily be the definitive longest anchored and 577floating string. This will be what the optimiser of the Perl that you 578are using thinks is the longest. If you believe that the result is wrong 579please report it via the L<perlbug> utility. 580 581=item regname($name,$all) 582 583Returns the contents of a named buffer of the last successful match. If 584$all is true, then returns an array ref containing one entry per buffer, 585otherwise returns the first defined buffer. 586 587=item regnames($all) 588 589Returns a list of all of the named buffers defined in the last successful 590match. If $all is true, then it returns all names defined, if not it returns 591only names which were involved in the match. 592 593=item regnames_count() 594 595Returns the number of distinct names defined in the pattern used 596for the last successful match. 597 598B<Note:> this result is always the actual number of distinct 599named buffers defined, it may not actually match that which is 600returned by C<regnames()> and related routines when those routines 601have not been called with the $all parameter set. 602 603=back 604 605=head1 SEE ALSO 606 607L<perlmodlib/Pragmatic Modules>. 608 609=cut 610