1package re; 2 3# pragma for controlling the regexp engine 4use strict; 5use warnings; 6 7our $VERSION = "0.11"; 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 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 $ENV{PERL_RE_COLORS} ||= qq'\t\t> <\t> <\t\t'; 33 } 34 35} 36 37my %flags = ( 38 COMPILE => 0x0000FF, 39 PARSE => 0x000001, 40 OPTIMISE => 0x000002, 41 TRIEC => 0x000004, 42 DUMP => 0x000008, 43 FLAGS => 0x000010, 44 45 EXECUTE => 0x00FF00, 46 INTUIT => 0x000100, 47 MATCH => 0x000200, 48 TRIEE => 0x000400, 49 50 EXTRA => 0xFF0000, 51 TRIEM => 0x010000, 52 OFFSETS => 0x020000, 53 OFFSETSDBG => 0x040000, 54 STATE => 0x080000, 55 OPTIMISEM => 0x100000, 56 STACK => 0x280000, 57 BUFFERS => 0x400000, 58 GPOS => 0x800000, 59); 60$flags{ALL} = -1 & ~($flags{OFFSETS}|$flags{OFFSETSDBG}|$flags{BUFFERS}); 61$flags{All} = $flags{all} = $flags{DUMP} | $flags{EXECUTE}; 62$flags{Extra} = $flags{EXECUTE} | $flags{COMPILE} | $flags{GPOS}; 63$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 67if (defined &DynaLoader::boot_DynaLoader) { 68 require XSLoader; 69 XSLoader::load( __PACKAGE__, $VERSION); 70} 71# else we're miniperl 72# We need to work for miniperl, because the XS toolchain uses Text::Wrap, which 73# uses re 'taint'. 74 75sub _load_unload { 76 my ($on)= @_; 77 if ($on) { 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 83 # in C resolves to a structure containing the regexp 84 # hooks. Setting it to a random integer will guarantee 85 # segfaults. 86 $^H{regcomp} = install(); 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); 122 last; 123 } elsif (exists $bitmask{$s}) { 124 $bits |= $bitmask{$s}; 125 } elsif ($EXPORT_OK{$s}) { 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 $^H &= ~ bits(0, @_); 146} 147 1481; 149 150__END__ 151 152=head1 NAME 153 154re - Perl pragma to alter regular expression behaviour 155 156=head1 SYNOPSIS 157 158 use re 'taint'; 159 ($x) = ($^X =~ /^(.*)$/s); # $x is tainted here 160 161 $pat = '(?{ $foo = 1 })'; 162 use re 'eval'; 163 /foo${pat}bar/; # won't fail (when not under -T switch) 164 165 { 166 no re 'taint'; # the default 167 ($x) = ($^X =~ /^(.*)$/s); # $x is not tainted here 168 169 no re 'eval'; # the default 170 /foo${pat}bar/; # disallowed (with or without -T switch) 171 } 172 173 use re 'debug'; # output debugging info during 174 /^(.*)$/s; # compile and run time 175 176 177 use re 'debugcolor'; # same as 'debug', but with colored output 178 ... 179 180 use re qw(Debug All); # Finer tuned debugging options. 181 use re qw(Debug More); 182 no re qw(Debug ALL); # Turn of all re debugging in this scope 183 184 use re qw(is_regexp regexp_pattern); # import utility functions 185 my ($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. 190 191(We use $^X in these examples because it's tainted by default.) 192 193=head1 DESCRIPTION 194 195=head2 'taint' mode 196 197When C<use re 'taint'> is in effect, and a tainted string is the target 198of a regexp, the regexp memories (or values returned by the m// operator 199in list context) are tainted. This feature is useful when regexp operations 200on tainted data aren't meant to extract safe substrings, but to perform 201other transformations. 202 203=head2 'eval' mode 204 205When C<use re 'eval'> is in effect, a regexp is allowed to contain 206C<(?{ ... })> zero-width assertions and C<(??{ ... })> postponed 207subexpressions, even if the regular expression contains 208variable interpolation. That is normally disallowed, since it is a 209potential security risk. Note that this pragma is ignored when the regular 210expression is obtained from tainted data, i.e. evaluation is always 211disallowed with tainted regular expressions. See L<perlre/(?{ code })> 212and L<perlre/(??{ code })>. 213 214For the purpose of this pragma, interpolation of precompiled regular 215expressions (i.e., the result of C<qr//>) is I<not> considered variable 216interpolation. Thus: 217 218 /foo${pat}bar/ 219 220I<is> allowed if $pat is a precompiled regular expression, even 221if $pat contains C<(?{ ... })> assertions or C<(??{ ... })> subexpressions. 222 223=head2 'debug' mode 224 225When C<use re 'debug'> is in effect, perl emits debugging messages when 226compiling and using regular expressions. The output is the same as that 227obtained by running a C<-DDEBUGGING>-enabled perl interpreter with the 228B<-Dr> switch. It may be quite voluminous depending on the complexity 229of the match. Using C<debugcolor> instead of C<debug> enables a 230form of output that can be used to get a colorful display on terminals 231that understand termcap color sequences. Set C<$ENV{PERL_RE_TC}> to a 232comma-separated list of C<termcap> properties to use for highlighting 233strings on/off, pre-point part on/off. 234See L<perldebug/"Debugging regular expressions"> for additional info. 235 236As of 5.9.5 the directive C<use re 'debug'> and its equivalents are 237lexically scoped, as the other directives are. However they have both 238compile-time and run-time effects. 239 240See L<perlmodlib/Pragmatic Modules>. 241 242=head2 'Debug' mode 243 244Similarly C<use re 'Debug'> produces debugging output, the difference 245being that it allows the fine tuning of what debugging output will be 246emitted. Options are divided into three groups, those related to 247compilation, those related to execution and those related to special 248purposes. The options are as follows: 249 250=over 4 251 252=item Compile related options 253 254=over 4 255 256=item COMPILE 257 258Turns on all compile related debug options. 259 260=item PARSE 261 262Turns on debug output related to the process of parsing the pattern. 263 264=item OPTIMISE 265 266Enables output related to the optimisation phase of compilation. 267 268=item TRIEC 269 270Detailed info about trie compilation. 271 272=item DUMP 273 274Dump the final program out after it is compiled and optimised. 275 276=back 277 278=item Execute related options 279 280=over 4 281 282=item EXECUTE 283 284Turns on all execute related debug options. 285 286=item MATCH 287 288Turns on debugging of the main matching loop. 289 290=item TRIEE 291 292Extra debugging of how tries execute. 293 294=item INTUIT 295 296Enable debugging of start point optimisations. 297 298=back 299 300=item Extra debugging options 301 302=over 4 303 304=item EXTRA 305 306Turns on all "extra" debugging options. 307 308=item BUFFERS 309 310Enable debugging the capture buffer storage during match. Warning, 311this can potentially produce extremely large output. 312 313=item TRIEM 314 315Enable enhanced TRIE debugging. Enhances both TRIEE 316and TRIEC. 317 318=item STATE 319 320Enable debugging of states in the engine. 321 322=item STACK 323 324Enable debugging of the recursion stack in the engine. Enabling 325or disabling this option automatically does the same for debugging 326states as well. This output from this can be quite large. 327 328=item OPTIMISEM 329 330Enable enhanced optimisation debugging and start point optimisations. 331Probably not useful except when debugging the regexp engine itself. 332 333=item OFFSETS 334 335Dump offset information. This can be used to see how regops correlate 336to the pattern. Output format is 337 338 NODENUM:POSITION[LENGTH] 339 340Where 1 is the position of the first char in the string. Note that position 341can be 0, or larger than the actual length of the pattern, likewise length 342can be zero. 343 344=item OFFSETSDBG 345 346Enable debugging of offsets information. This emits copious 347amounts of trace information and doesn't mesh well with other 348debug options. 349 350Almost definitely only useful to people hacking 351on the offsets part of the debug engine. 352 353=back 354 355=item Other useful flags 356 357These are useful shortcuts to save on the typing. 358 359=over 4 360 361=item ALL 362 363Enable all options at once except OFFSETS, OFFSETSDBG and BUFFERS 364 365=item All 366 367Enable DUMP and all execute options. Equivalent to: 368 369 use re 'debug'; 370 371=item MORE 372 373=item More 374 375Enable TRIEM and all execute compile and execute options. 376 377=back 378 379=back 380 381As of 5.9.5 the directive C<use re 'debug'> and its equivalents are 382lexically scoped, as the other directives are. However they have both 383compile-time and run-time effects. 384 385=head2 Exportable Functions 386 387As of perl 5.9.5 're' debug contains a number of utility functions that 388may be optionally exported into the caller's namespace. They are listed 389below. 390 391=over 4 392 393=item is_regexp($ref) 394 395Returns true if the argument is a compiled regular expression as returned 396by C<qr//>, false if it is not. 397 398This function will not be confused by overloading or blessing. In 399internals terms, this extracts the regexp pointer out of the 400PERL_MAGIC_qr structure so it it cannot be fooled. 401 402=item regexp_pattern($ref) 403 404If the argument is a compiled regular expression as returned by C<qr//>, 405then this function returns the pattern. 406 407In list context it returns a two element list, the first element 408containing the pattern and the second containing the modifiers used when 409the pattern was compiled. 410 411 my ($pat, $mods) = regexp_pattern($ref); 412 413In scalar context it returns the same as perl would when stringifying a raw 414C<qr//> with the same pattern inside. If the argument is not a compiled 415reference then this routine returns false but defined in scalar context, 416and the empty list in list context. Thus the following 417 418 if (regexp_pattern($ref) eq '(?i-xsm:foo)') 419 420will be warning free regardless of what $ref actually is. 421 422Like C<is_regexp> this function will not be confused by overloading 423or blessing of the object. 424 425=item regmust($ref) 426 427If the argument is a compiled regular expression as returned by C<qr//>, 428then this function returns what the optimiser considers to be the longest 429anchored fixed string and longest floating fixed string in the pattern. 430 431A I<fixed string> is defined as being a substring that must appear for the 432pattern to match. An I<anchored fixed string> is a fixed string that must 433appear at a particular offset from the beginning of the match. A I<floating 434fixed string> is defined as a fixed string that can appear at any point in 435a range of positions relative to the start of the match. For example, 436 437 my $qr = qr/here .* there/x; 438 my ($anchored, $floating) = regmust($qr); 439 print "anchored:'$anchored'\nfloating:'$floating'\n"; 440 441results in 442 443 anchored:'here' 444 floating:'there' 445 446Because the C<here> is before the C<.*> in the pattern, its position 447can be determined exactly. That's not true, however, for the C<there>; 448it could appear at any point after where the anchored string appeared. 449Perl uses both for its optimisations, prefering the longer, or, if they are 450equal, the floating. 451 452B<NOTE:> This may not necessarily be the definitive longest anchored and 453floating string. This will be what the optimiser of the Perl that you 454are using thinks is the longest. If you believe that the result is wrong 455please report it via the L<perlbug> utility. 456 457=item regname($name,$all) 458 459Returns the contents of a named buffer of the last successful match. If 460$all is true, then returns an array ref containing one entry per buffer, 461otherwise returns the first defined buffer. 462 463=item regnames($all) 464 465Returns a list of all of the named buffers defined in the last successful 466match. If $all is true, then it returns all names defined, if not it returns 467only names which were involved in the match. 468 469=item regnames_count() 470 471Returns the number of distinct names defined in the pattern used 472for the last successful match. 473 474B<Note:> this result is always the actual number of distinct 475named buffers defined, it may not actually match that which is 476returned by C<regnames()> and related routines when those routines 477have not been called with the $all parameter set. 478 479=back 480 481=head1 SEE ALSO 482 483L<perlmodlib/Pragmatic Modules>. 484 485=cut 486