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86530b38 AT |
1 | # EXTRACT VARIOUSLY DELIMITED TEXT SEQUENCES FROM STRINGS. |
2 | # FOR FULL DOCUMENTATION SEE Balanced.pod | |
3 | ||
4 | use 5.005; | |
5 | use strict; | |
6 | ||
7 | package Text::Balanced; | |
8 | ||
9 | use Exporter; | |
10 | use SelfLoader; | |
11 | use vars qw { $VERSION @ISA %EXPORT_TAGS }; | |
12 | ||
13 | $VERSION = '1.89'; | |
14 | @ISA = qw ( Exporter ); | |
15 | ||
16 | %EXPORT_TAGS = ( ALL => [ qw( | |
17 | &extract_delimited | |
18 | &extract_bracketed | |
19 | &extract_quotelike | |
20 | &extract_codeblock | |
21 | &extract_variable | |
22 | &extract_tagged | |
23 | &extract_multiple | |
24 | ||
25 | &gen_delimited_pat | |
26 | &gen_extract_tagged | |
27 | ||
28 | &delimited_pat | |
29 | ) ] ); | |
30 | ||
31 | Exporter::export_ok_tags('ALL'); | |
32 | ||
33 | ## | |
34 | ## These shenanagins are to avoid using $& in perl5.6+ | |
35 | ## | |
36 | my $GetMatchedText = ($] < 5.006) ? eval 'sub { $& } ' | |
37 | : eval 'sub { | |
38 | substr($_[0], $-[0], $+[0] - $-[0]) | |
39 | }'; | |
40 | ||
41 | ||
42 | # PROTOTYPES | |
43 | ||
44 | sub _match_bracketed($$$$$$); | |
45 | sub _match_variable($$); | |
46 | sub _match_codeblock($$$$$$$); | |
47 | sub _match_quotelike($$$$); | |
48 | ||
49 | # HANDLE RETURN VALUES IN VARIOUS CONTEXTS | |
50 | ||
51 | sub _failmsg { | |
52 | my ($message, $pos) = @_; | |
53 | $@ = bless { error=>$message, pos=>$pos }, "Text::Balanced::ErrorMsg"; | |
54 | } | |
55 | ||
56 | sub _fail | |
57 | { | |
58 | my ($wantarray, $textref, $message, $pos) = @_; | |
59 | _failmsg $message, $pos if $message; | |
60 | return ("",$$textref,"") if $wantarray; | |
61 | return undef; | |
62 | } | |
63 | ||
64 | sub _succeed | |
65 | { | |
66 | $@ = undef; | |
67 | my ($wantarray,$textref) = splice @_, 0, 2; | |
68 | my ($extrapos, $extralen) = @_>18 ? splice(@_, -2, 2) : (0,0); | |
69 | my ($startlen) = $_[5]; | |
70 | my $remainderpos = $_[2]; | |
71 | if ($wantarray) | |
72 | { | |
73 | my @res; | |
74 | while (my ($from, $len) = splice @_, 0, 2) | |
75 | { | |
76 | push @res, substr($$textref,$from,$len); | |
77 | } | |
78 | if ($extralen) { # CORRECT FILLET | |
79 | my $extra = substr($res[0], $extrapos-$startlen, $extralen, "\n"); | |
80 | $res[1] = "$extra$res[1]"; | |
81 | eval { substr($$textref,$remainderpos,0) = $extra; | |
82 | substr($$textref,$extrapos,$extralen,"\n")} ; | |
83 | #REARRANGE HERE DOC AND FILLET IF POSSIBLE | |
84 | pos($$textref) = $remainderpos-$extralen+1; # RESET \G | |
85 | } | |
86 | else { | |
87 | pos($$textref) = $remainderpos; # RESET \G | |
88 | } | |
89 | return @res; | |
90 | } | |
91 | else | |
92 | { | |
93 | my $match = substr($$textref,$_[0],$_[1]); | |
94 | substr($match,$extrapos-$_[0]-$startlen,$extralen,"") if $extralen; | |
95 | my $extra = $extralen | |
96 | ? substr($$textref, $extrapos, $extralen)."\n" : ""; | |
97 | eval {substr($$textref,$_[4],$_[1]+$_[5])=$extra} ; #CHOP OUT PREFIX & MATCH, IF POSSIBLE | |
98 | pos($$textref) = $_[4]; # RESET \G | |
99 | return $match; | |
100 | } | |
101 | } | |
102 | ||
103 | # BUILD A PATTERN MATCHING A SIMPLE DELIMITED STRING | |
104 | ||
105 | sub gen_delimited_pat($;$) # ($delimiters;$escapes) | |
106 | { | |
107 | my ($dels, $escs) = @_; | |
108 | return "" unless $dels =~ /\S/; | |
109 | $escs = '\\' unless $escs; | |
110 | $escs .= substr($escs,-1) x (length($dels)-length($escs)); | |
111 | my @pat = (); | |
112 | my $i; | |
113 | for ($i=0; $i<length $dels; $i++) | |
114 | { | |
115 | my $del = quotemeta substr($dels,$i,1); | |
116 | my $esc = quotemeta substr($escs,$i,1); | |
117 | if ($del eq $esc) | |
118 | { | |
119 | push @pat, "$del(?:[^$del]*(?:(?:$del$del)[^$del]*)*)$del"; | |
120 | } | |
121 | else | |
122 | { | |
123 | push @pat, "$del(?:[^$esc$del]*(?:$esc.[^$esc$del]*)*)$del"; | |
124 | } | |
125 | } | |
126 | my $pat = join '|', @pat; | |
127 | return "(?:$pat)"; | |
128 | } | |
129 | ||
130 | *delimited_pat = \&gen_delimited_pat; | |
131 | ||
132 | ||
133 | # THE EXTRACTION FUNCTIONS | |
134 | ||
135 | sub extract_delimited (;$$$$) | |
136 | { | |
137 | my $textref = defined $_[0] ? \$_[0] : \$_; | |
138 | my $wantarray = wantarray; | |
139 | my $del = defined $_[1] ? $_[1] : qq{\'\"\`}; | |
140 | my $pre = defined $_[2] ? $_[2] : '\s*'; | |
141 | my $esc = defined $_[3] ? $_[3] : qq{\\}; | |
142 | my $pat = gen_delimited_pat($del, $esc); | |
143 | my $startpos = pos $$textref || 0; | |
144 | return _fail($wantarray, $textref, "Not a delimited pattern", 0) | |
145 | unless $$textref =~ m/\G($pre)($pat)/gc; | |
146 | my $prelen = length($1); | |
147 | my $matchpos = $startpos+$prelen; | |
148 | my $endpos = pos $$textref; | |
149 | return _succeed $wantarray, $textref, | |
150 | $matchpos, $endpos-$matchpos, # MATCH | |
151 | $endpos, length($$textref)-$endpos, # REMAINDER | |
152 | $startpos, $prelen; # PREFIX | |
153 | } | |
154 | ||
155 | sub extract_bracketed (;$$$) | |
156 | { | |
157 | my $textref = defined $_[0] ? \$_[0] : \$_; | |
158 | my $ldel = defined $_[1] ? $_[1] : '{([<'; | |
159 | my $pre = defined $_[2] ? $_[2] : '\s*'; | |
160 | my $wantarray = wantarray; | |
161 | my $qdel = ""; | |
162 | my $quotelike; | |
163 | $ldel =~ s/'//g and $qdel .= q{'}; | |
164 | $ldel =~ s/"//g and $qdel .= q{"}; | |
165 | $ldel =~ s/`//g and $qdel .= q{`}; | |
166 | $ldel =~ s/q//g and $quotelike = 1; | |
167 | $ldel =~ tr/[](){}<>\0-\377/[[(({{<</ds; | |
168 | my $rdel = $ldel; | |
169 | unless ($rdel =~ tr/[({</])}>/) | |
170 | { | |
171 | return _fail $wantarray, $textref, | |
172 | "Did not find a suitable bracket in delimiter: \"$_[1]\"", | |
173 | 0; | |
174 | } | |
175 | my $posbug = pos; | |
176 | $ldel = join('|', map { quotemeta $_ } split('', $ldel)); | |
177 | $rdel = join('|', map { quotemeta $_ } split('', $rdel)); | |
178 | pos = $posbug; | |
179 | ||
180 | my $startpos = pos $$textref || 0; | |
181 | my @match = _match_bracketed($textref,$pre, $ldel, $qdel, $quotelike, $rdel); | |
182 | ||
183 | return _fail ($wantarray, $textref) unless @match; | |
184 | ||
185 | return _succeed ( $wantarray, $textref, | |
186 | $match[2], $match[5]+2, # MATCH | |
187 | @match[8,9], # REMAINDER | |
188 | @match[0,1], # PREFIX | |
189 | ); | |
190 | } | |
191 | ||
192 | sub _match_bracketed($$$$$$) # $textref, $pre, $ldel, $qdel, $quotelike, $rdel | |
193 | { | |
194 | my ($textref, $pre, $ldel, $qdel, $quotelike, $rdel) = @_; | |
195 | my ($startpos, $ldelpos, $endpos) = (pos $$textref = pos $$textref||0); | |
196 | unless ($$textref =~ m/\G$pre/gc) | |
197 | { | |
198 | _failmsg "Did not find prefix: /$pre/", $startpos; | |
199 | return; | |
200 | } | |
201 | ||
202 | $ldelpos = pos $$textref; | |
203 | ||
204 | unless ($$textref =~ m/\G($ldel)/gc) | |
205 | { | |
206 | _failmsg "Did not find opening bracket after prefix: \"$pre\"", | |
207 | pos $$textref; | |
208 | pos $$textref = $startpos; | |
209 | return; | |
210 | } | |
211 | ||
212 | my @nesting = ( $1 ); | |
213 | my $textlen = length $$textref; | |
214 | while (pos $$textref < $textlen) | |
215 | { | |
216 | next if $$textref =~ m/\G\\./gcs; | |
217 | ||
218 | if ($$textref =~ m/\G($ldel)/gc) | |
219 | { | |
220 | push @nesting, $1; | |
221 | } | |
222 | elsif ($$textref =~ m/\G($rdel)/gc) | |
223 | { | |
224 | my ($found, $brackettype) = ($1, $1); | |
225 | if ($#nesting < 0) | |
226 | { | |
227 | _failmsg "Unmatched closing bracket: \"$found\"", | |
228 | pos $$textref; | |
229 | pos $$textref = $startpos; | |
230 | return; | |
231 | } | |
232 | my $expected = pop(@nesting); | |
233 | $expected =~ tr/({[</)}]>/; | |
234 | if ($expected ne $brackettype) | |
235 | { | |
236 | _failmsg qq{Mismatched closing bracket: expected "$expected" but found "$found"}, | |
237 | pos $$textref; | |
238 | pos $$textref = $startpos; | |
239 | return; | |
240 | } | |
241 | last if $#nesting < 0; | |
242 | } | |
243 | elsif ($qdel && $$textref =~ m/\G([$qdel])/gc) | |
244 | { | |
245 | $$textref =~ m/\G[^\\$1]*(?:\\.[^\\$1]*)*(\Q$1\E)/gsc and next; | |
246 | _failmsg "Unmatched embedded quote ($1)", | |
247 | pos $$textref; | |
248 | pos $$textref = $startpos; | |
249 | return; | |
250 | } | |
251 | elsif ($quotelike && _match_quotelike($textref,"",1,0)) | |
252 | { | |
253 | next; | |
254 | } | |
255 | ||
256 | else { $$textref =~ m/\G(?:[a-zA-Z0-9]+|.)/gcs } | |
257 | } | |
258 | if ($#nesting>=0) | |
259 | { | |
260 | _failmsg "Unmatched opening bracket(s): " | |
261 | . join("..",@nesting)."..", | |
262 | pos $$textref; | |
263 | pos $$textref = $startpos; | |
264 | return; | |
265 | } | |
266 | ||
267 | $endpos = pos $$textref; | |
268 | ||
269 | return ( | |
270 | $startpos, $ldelpos-$startpos, # PREFIX | |
271 | $ldelpos, 1, # OPENING BRACKET | |
272 | $ldelpos+1, $endpos-$ldelpos-2, # CONTENTS | |
273 | $endpos-1, 1, # CLOSING BRACKET | |
274 | $endpos, length($$textref)-$endpos, # REMAINDER | |
275 | ); | |
276 | } | |
277 | ||
278 | sub revbracket($) | |
279 | { | |
280 | my $brack = reverse $_[0]; | |
281 | $brack =~ tr/[({</])}>/; | |
282 | return $brack; | |
283 | } | |
284 | ||
285 | my $XMLNAME = q{[a-zA-Z_:][a-zA-Z0-9_:.-]*}; | |
286 | ||
287 | sub extract_tagged (;$$$$$) # ($text, $opentag, $closetag, $pre, \%options) | |
288 | { | |
289 | my $textref = defined $_[0] ? \$_[0] : \$_; | |
290 | my $ldel = $_[1]; | |
291 | my $rdel = $_[2]; | |
292 | my $pre = defined $_[3] ? $_[3] : '\s*'; | |
293 | my %options = defined $_[4] ? %{$_[4]} : (); | |
294 | my $omode = defined $options{fail} ? $options{fail} : ''; | |
295 | my $bad = ref($options{reject}) eq 'ARRAY' ? join('|', @{$options{reject}}) | |
296 | : defined($options{reject}) ? $options{reject} | |
297 | : '' | |
298 | ; | |
299 | my $ignore = ref($options{ignore}) eq 'ARRAY' ? join('|', @{$options{ignore}}) | |
300 | : defined($options{ignore}) ? $options{ignore} | |
301 | : '' | |
302 | ; | |
303 | ||
304 | if (!defined $ldel) { $ldel = '<\w+(?:' . gen_delimited_pat(q{'"}) . '|[^>])*>'; } | |
305 | $@ = undef; | |
306 | ||
307 | my @match = _match_tagged($textref, $pre, $ldel, $rdel, $omode, $bad, $ignore); | |
308 | ||
309 | return _fail(wantarray, $textref) unless @match; | |
310 | return _succeed wantarray, $textref, | |
311 | $match[2], $match[3]+$match[5]+$match[7], # MATCH | |
312 | @match[8..9,0..1,2..7]; # REM, PRE, BITS | |
313 | } | |
314 | ||
315 | sub _match_tagged # ($$$$$$$) | |
316 | { | |
317 | my ($textref, $pre, $ldel, $rdel, $omode, $bad, $ignore) = @_; | |
318 | my $rdelspec; | |
319 | ||
320 | my ($startpos, $opentagpos, $textpos, $parapos, $closetagpos, $endpos) = ( pos($$textref) = pos($$textref)||0 ); | |
321 | ||
322 | unless ($$textref =~ m/\G($pre)/gc) | |
323 | { | |
324 | _failmsg "Did not find prefix: /$pre/", pos $$textref; | |
325 | goto failed; | |
326 | } | |
327 | ||
328 | $opentagpos = pos($$textref); | |
329 | ||
330 | unless ($$textref =~ m/\G$ldel/gc) | |
331 | { | |
332 | _failmsg "Did not find opening tag: /$ldel/", pos $$textref; | |
333 | goto failed; | |
334 | } | |
335 | ||
336 | $textpos = pos($$textref); | |
337 | ||
338 | if (!defined $rdel) | |
339 | { | |
340 | $rdelspec = &$GetMatchedText($$textref); | |
341 | ||
342 | unless ($rdelspec =~ s/\A([[(<{]+)($XMLNAME).*/ quotemeta "$1\/$2". revbracket($1) /oes) | |
343 | { | |
344 | _failmsg "Unable to construct closing tag to match: $rdel", | |
345 | pos $$textref; | |
346 | goto failed; | |
347 | } | |
348 | } | |
349 | else | |
350 | { | |
351 | $rdelspec = eval "qq{$rdel}"; | |
352 | } | |
353 | ||
354 | while (pos($$textref) < length($$textref)) | |
355 | { | |
356 | next if $$textref =~ m/\G\\./gc; | |
357 | ||
358 | if ($$textref =~ m/\G(\n[ \t]*\n)/gc ) | |
359 | { | |
360 | $parapos = pos($$textref) - length($1) | |
361 | unless defined $parapos; | |
362 | } | |
363 | elsif ($$textref =~ m/\G($rdelspec)/gc ) | |
364 | { | |
365 | $closetagpos = pos($$textref)-length($1); | |
366 | goto matched; | |
367 | } | |
368 | elsif ($ignore && $$textref =~ m/\G(?:$ignore)/gc) | |
369 | { | |
370 | next; | |
371 | } | |
372 | elsif ($bad && $$textref =~ m/\G($bad)/gcs) | |
373 | { | |
374 | pos($$textref) -= length($1); # CUT OFF WHATEVER CAUSED THE SHORTNESS | |
375 | goto short if ($omode eq 'PARA' || $omode eq 'MAX'); | |
376 | _failmsg "Found invalid nested tag: $1", pos $$textref; | |
377 | goto failed; | |
378 | } | |
379 | elsif ($$textref =~ m/\G($ldel)/gc) | |
380 | { | |
381 | my $tag = $1; | |
382 | pos($$textref) -= length($tag); # REWIND TO NESTED TAG | |
383 | unless (_match_tagged(@_)) # MATCH NESTED TAG | |
384 | { | |
385 | goto short if $omode eq 'PARA' || $omode eq 'MAX'; | |
386 | _failmsg "Found unbalanced nested tag: $tag", | |
387 | pos $$textref; | |
388 | goto failed; | |
389 | } | |
390 | } | |
391 | else { $$textref =~ m/./gcs } | |
392 | } | |
393 | ||
394 | short: | |
395 | $closetagpos = pos($$textref); | |
396 | goto matched if $omode eq 'MAX'; | |
397 | goto failed unless $omode eq 'PARA'; | |
398 | ||
399 | if (defined $parapos) { pos($$textref) = $parapos } | |
400 | else { $parapos = pos($$textref) } | |
401 | ||
402 | return ( | |
403 | $startpos, $opentagpos-$startpos, # PREFIX | |
404 | $opentagpos, $textpos-$opentagpos, # OPENING TAG | |
405 | $textpos, $parapos-$textpos, # TEXT | |
406 | $parapos, 0, # NO CLOSING TAG | |
407 | $parapos, length($$textref)-$parapos, # REMAINDER | |
408 | ); | |
409 | ||
410 | matched: | |
411 | $endpos = pos($$textref); | |
412 | return ( | |
413 | $startpos, $opentagpos-$startpos, # PREFIX | |
414 | $opentagpos, $textpos-$opentagpos, # OPENING TAG | |
415 | $textpos, $closetagpos-$textpos, # TEXT | |
416 | $closetagpos, $endpos-$closetagpos, # CLOSING TAG | |
417 | $endpos, length($$textref)-$endpos, # REMAINDER | |
418 | ); | |
419 | ||
420 | failed: | |
421 | _failmsg "Did not find closing tag", pos $$textref unless $@; | |
422 | pos($$textref) = $startpos; | |
423 | return; | |
424 | } | |
425 | ||
426 | sub extract_variable (;$$) | |
427 | { | |
428 | my $textref = defined $_[0] ? \$_[0] : \$_; | |
429 | return ("","","") unless defined $$textref; | |
430 | my $pre = defined $_[1] ? $_[1] : '\s*'; | |
431 | ||
432 | my @match = _match_variable($textref,$pre); | |
433 | ||
434 | return _fail wantarray, $textref unless @match; | |
435 | ||
436 | return _succeed wantarray, $textref, | |
437 | @match[2..3,4..5,0..1]; # MATCH, REMAINDER, PREFIX | |
438 | } | |
439 | ||
440 | sub _match_variable($$) | |
441 | { | |
442 | # $# | |
443 | # $^ | |
444 | # $$ | |
445 | my ($textref, $pre) = @_; | |
446 | my $startpos = pos($$textref) = pos($$textref)||0; | |
447 | unless ($$textref =~ m/\G($pre)/gc) | |
448 | { | |
449 | _failmsg "Did not find prefix: /$pre/", pos $$textref; | |
450 | return; | |
451 | } | |
452 | my $varpos = pos($$textref); | |
453 | unless ($$textref =~ m{\G\$\s*(\d+|[][&`'+*./|,";%=~:?!\@<>()-]|\^[a-z]?)}gci) | |
454 | { | |
455 | unless ($$textref =~ m/\G((\$#?|[*\@\%]|\\&)+)/gc) | |
456 | { | |
457 | _failmsg "Did not find leading dereferencer", pos $$textref; | |
458 | pos $$textref = $startpos; | |
459 | return; | |
460 | } | |
461 | my $deref = $1; | |
462 | ||
463 | unless ($$textref =~ m/\G\s*(?:::|')?(?:[_a-z]\w*(?:::|'))*[_a-z]\w*/gci | |
464 | or _match_codeblock($textref, "", '\{', '\}', '\{', '\}', 0) | |
465 | or $deref eq '$#' or $deref eq '$$' ) | |
466 | { | |
467 | _failmsg "Bad identifier after dereferencer", pos $$textref; | |
468 | pos $$textref = $startpos; | |
469 | return; | |
470 | } | |
471 | } | |
472 | ||
473 | while (1) | |
474 | { | |
475 | next if _match_codeblock($textref, | |
476 | qr/\s*->\s*(?:[_a-zA-Z]\w+\s*)?/, | |
477 | qr/[({[]/, qr/[)}\]]/, | |
478 | qr/[({[]/, qr/[)}\]]/, 0); | |
479 | next if _match_codeblock($textref, | |
480 | qr/\s*/, qr/[{[]/, qr/[}\]]/, | |
481 | qr/[{[]/, qr/[}\]]/, 0); | |
482 | next if _match_variable($textref,'\s*->\s*'); | |
483 | next if $$textref =~ m/\G\s*->\s*\w+(?![{([])/gc; | |
484 | last; | |
485 | } | |
486 | ||
487 | my $endpos = pos($$textref); | |
488 | return ($startpos, $varpos-$startpos, | |
489 | $varpos, $endpos-$varpos, | |
490 | $endpos, length($$textref)-$endpos | |
491 | ); | |
492 | } | |
493 | ||
494 | sub extract_codeblock (;$$$$$) | |
495 | { | |
496 | my $textref = defined $_[0] ? \$_[0] : \$_; | |
497 | my $wantarray = wantarray; | |
498 | my $ldel_inner = defined $_[1] ? $_[1] : '{'; | |
499 | my $pre = defined $_[2] ? $_[2] : '\s*'; | |
500 | my $ldel_outer = defined $_[3] ? $_[3] : $ldel_inner; | |
501 | my $rd = $_[4]; | |
502 | my $rdel_inner = $ldel_inner; | |
503 | my $rdel_outer = $ldel_outer; | |
504 | my $posbug = pos; | |
505 | for ($ldel_inner, $ldel_outer) { tr/[]()<>{}\0-\377/[[((<<{{/ds } | |
506 | for ($rdel_inner, $rdel_outer) { tr/[]()<>{}\0-\377/]]))>>}}/ds } | |
507 | for ($ldel_inner, $ldel_outer, $rdel_inner, $rdel_outer) | |
508 | { | |
509 | $_ = '('.join('|',map { quotemeta $_ } split('',$_)).')' | |
510 | } | |
511 | pos = $posbug; | |
512 | ||
513 | my @match = _match_codeblock($textref, $pre, | |
514 | $ldel_outer, $rdel_outer, | |
515 | $ldel_inner, $rdel_inner, | |
516 | $rd); | |
517 | return _fail($wantarray, $textref) unless @match; | |
518 | return _succeed($wantarray, $textref, | |
519 | @match[2..3,4..5,0..1] # MATCH, REMAINDER, PREFIX | |
520 | ); | |
521 | ||
522 | } | |
523 | ||
524 | sub _match_codeblock($$$$$$$) | |
525 | { | |
526 | my ($textref, $pre, $ldel_outer, $rdel_outer, $ldel_inner, $rdel_inner, $rd) = @_; | |
527 | my $startpos = pos($$textref) = pos($$textref) || 0; | |
528 | unless ($$textref =~ m/\G($pre)/gc) | |
529 | { | |
530 | _failmsg qq{Did not match prefix /$pre/ at"} . | |
531 | substr($$textref,pos($$textref),20) . | |
532 | q{..."}, | |
533 | pos $$textref; | |
534 | return; | |
535 | } | |
536 | my $codepos = pos($$textref); | |
537 | unless ($$textref =~ m/\G($ldel_outer)/gc) # OUTERMOST DELIMITER | |
538 | { | |
539 | _failmsg qq{Did not find expected opening bracket at "} . | |
540 | substr($$textref,pos($$textref),20) . | |
541 | q{..."}, | |
542 | pos $$textref; | |
543 | pos $$textref = $startpos; | |
544 | return; | |
545 | } | |
546 | my $closing = $1; | |
547 | $closing =~ tr/([<{/)]>}/; | |
548 | my $matched; | |
549 | my $patvalid = 1; | |
550 | while (pos($$textref) < length($$textref)) | |
551 | { | |
552 | $matched = ''; | |
553 | if ($rd && $$textref =~ m#\G(\Q(?)\E|\Q(s?)\E|\Q(s)\E)#gc) | |
554 | { | |
555 | $patvalid = 0; | |
556 | next; | |
557 | } | |
558 | ||
559 | if ($$textref =~ m/\G\s*#.*/gc) | |
560 | { | |
561 | next; | |
562 | } | |
563 | ||
564 | if ($$textref =~ m/\G\s*($rdel_outer)/gc) | |
565 | { | |
566 | unless ($matched = ($closing && $1 eq $closing) ) | |
567 | { | |
568 | next if $1 eq '>'; # MIGHT BE A "LESS THAN" | |
569 | _failmsg q{Mismatched closing bracket at "} . | |
570 | substr($$textref,pos($$textref),20) . | |
571 | qq{...". Expected '$closing'}, | |
572 | pos $$textref; | |
573 | } | |
574 | last; | |
575 | } | |
576 | ||
577 | if (_match_variable($textref,'\s*') || | |
578 | _match_quotelike($textref,'\s*',$patvalid,$patvalid) ) | |
579 | { | |
580 | $patvalid = 0; | |
581 | next; | |
582 | } | |
583 | ||
584 | ||
585 | # NEED TO COVER MANY MORE CASES HERE!!! | |
586 | if ($$textref =~ m#\G\s*( [-+*x/%^&|.]=? | |
587 | | [!=]~ | |
588 | | =(?!>) | |
589 | | (\*\*|&&|\|\||<<|>>)=? | |
590 | | split|grep|map|return | |
591 | )#gcx) | |
592 | { | |
593 | $patvalid = 1; | |
594 | next; | |
595 | } | |
596 | ||
597 | if ( _match_codeblock($textref, '\s*', $ldel_inner, $rdel_inner, $ldel_inner, $rdel_inner, $rd) ) | |
598 | { | |
599 | $patvalid = 1; | |
600 | next; | |
601 | } | |
602 | ||
603 | if ($$textref =~ m/\G\s*$ldel_outer/gc) | |
604 | { | |
605 | _failmsg q{Improperly nested codeblock at "} . | |
606 | substr($$textref,pos($$textref),20) . | |
607 | q{..."}, | |
608 | pos $$textref; | |
609 | last; | |
610 | } | |
611 | ||
612 | $patvalid = 0; | |
613 | $$textref =~ m/\G\s*(\w+|[-=>]>|.|\Z)/gc; | |
614 | } | |
615 | continue { $@ = undef } | |
616 | ||
617 | unless ($matched) | |
618 | { | |
619 | _failmsg 'No match found for opening bracket', pos $$textref | |
620 | unless $@; | |
621 | return; | |
622 | } | |
623 | ||
624 | my $endpos = pos($$textref); | |
625 | return ( $startpos, $codepos-$startpos, | |
626 | $codepos, $endpos-$codepos, | |
627 | $endpos, length($$textref)-$endpos, | |
628 | ); | |
629 | } | |
630 | ||
631 | ||
632 | my %mods = ( | |
633 | 'none' => '[cgimsox]*', | |
634 | 'm' => '[cgimsox]*', | |
635 | 's' => '[cegimsox]*', | |
636 | 'tr' => '[cds]*', | |
637 | 'y' => '[cds]*', | |
638 | 'qq' => '', | |
639 | 'qx' => '', | |
640 | 'qw' => '', | |
641 | 'qr' => '[imsx]*', | |
642 | 'q' => '', | |
643 | ); | |
644 | ||
645 | sub extract_quotelike (;$$) | |
646 | { | |
647 | my $textref = $_[0] ? \$_[0] : \$_; | |
648 | my $wantarray = wantarray; | |
649 | my $pre = defined $_[1] ? $_[1] : '\s*'; | |
650 | ||
651 | my @match = _match_quotelike($textref,$pre,1,0); | |
652 | return _fail($wantarray, $textref) unless @match; | |
653 | return _succeed($wantarray, $textref, | |
654 | $match[2], $match[18]-$match[2], # MATCH | |
655 | @match[18,19], # REMAINDER | |
656 | @match[0,1], # PREFIX | |
657 | @match[2..17], # THE BITS | |
658 | @match[20,21], # ANY FILLET? | |
659 | ); | |
660 | }; | |
661 | ||
662 | sub _match_quotelike($$$$) # ($textref, $prepat, $allow_raw_match) | |
663 | { | |
664 | my ($textref, $pre, $rawmatch, $qmark) = @_; | |
665 | ||
666 | my ($textlen,$startpos, | |
667 | $oppos, | |
668 | $preld1pos,$ld1pos,$str1pos,$rd1pos, | |
669 | $preld2pos,$ld2pos,$str2pos,$rd2pos, | |
670 | $modpos) = ( length($$textref), pos($$textref) = pos($$textref) || 0 ); | |
671 | ||
672 | unless ($$textref =~ m/\G($pre)/gc) | |
673 | { | |
674 | _failmsg qq{Did not find prefix /$pre/ at "} . | |
675 | substr($$textref, pos($$textref), 20) . | |
676 | q{..."}, | |
677 | pos $$textref; | |
678 | return; | |
679 | } | |
680 | $oppos = pos($$textref); | |
681 | ||
682 | my $initial = substr($$textref,$oppos,1); | |
683 | ||
684 | if ($initial && $initial =~ m|^[\"\'\`]| | |
685 | || $rawmatch && $initial =~ m|^/| | |
686 | || $qmark && $initial =~ m|^\?|) | |
687 | { | |
688 | unless ($$textref =~ m/ \Q$initial\E [^\\$initial]* (\\.[^\\$initial]*)* \Q$initial\E /gcsx) | |
689 | { | |
690 | _failmsg qq{Did not find closing delimiter to match '$initial' at "} . | |
691 | substr($$textref, $oppos, 20) . | |
692 | q{..."}, | |
693 | pos $$textref; | |
694 | pos $$textref = $startpos; | |
695 | return; | |
696 | } | |
697 | $modpos= pos($$textref); | |
698 | $rd1pos = $modpos-1; | |
699 | ||
700 | if ($initial eq '/' || $initial eq '?') | |
701 | { | |
702 | $$textref =~ m/\G$mods{none}/gc | |
703 | } | |
704 | ||
705 | my $endpos = pos($$textref); | |
706 | return ( | |
707 | $startpos, $oppos-$startpos, # PREFIX | |
708 | $oppos, 0, # NO OPERATOR | |
709 | $oppos, 1, # LEFT DEL | |
710 | $oppos+1, $rd1pos-$oppos-1, # STR/PAT | |
711 | $rd1pos, 1, # RIGHT DEL | |
712 | $modpos, 0, # NO 2ND LDEL | |
713 | $modpos, 0, # NO 2ND STR | |
714 | $modpos, 0, # NO 2ND RDEL | |
715 | $modpos, $endpos-$modpos, # MODIFIERS | |
716 | $endpos, $textlen-$endpos, # REMAINDER | |
717 | ); | |
718 | } | |
719 | ||
720 | unless ($$textref =~ m{\G((?:m|s|qq|qx|qw|q|qr|tr|y)\b(?=\s*\S)|<<)}gc) | |
721 | { | |
722 | _failmsg q{No quotelike operator found after prefix at "} . | |
723 | substr($$textref, pos($$textref), 20) . | |
724 | q{..."}, | |
725 | pos $$textref; | |
726 | pos $$textref = $startpos; | |
727 | return; | |
728 | } | |
729 | ||
730 | my $op = $1; | |
731 | $preld1pos = pos($$textref); | |
732 | if ($op eq '<<') { | |
733 | $ld1pos = pos($$textref); | |
734 | my $label; | |
735 | if ($$textref =~ m{\G([A-Za-z_]\w*)}gc) { | |
736 | $label = $1; | |
737 | } | |
738 | elsif ($$textref =~ m{ \G ' ([^'\\]* (?:\\.[^'\\]*)*) ' | |
739 | | \G " ([^"\\]* (?:\\.[^"\\]*)*) " | |
740 | | \G ` ([^`\\]* (?:\\.[^`\\]*)*) ` | |
741 | }gcsx) { | |
742 | $label = $+; | |
743 | } | |
744 | else { | |
745 | $label = ""; | |
746 | } | |
747 | my $extrapos = pos($$textref); | |
748 | $$textref =~ m{.*\n}gc; | |
749 | $str1pos = pos($$textref); | |
750 | unless ($$textref =~ m{.*?\n(?=$label\n)}gc) { | |
751 | _failmsg qq{Missing here doc terminator ('$label') after "} . | |
752 | substr($$textref, $startpos, 20) . | |
753 | q{..."}, | |
754 | pos $$textref; | |
755 | pos $$textref = $startpos; | |
756 | return; | |
757 | } | |
758 | $rd1pos = pos($$textref); | |
759 | $$textref =~ m{$label\n}gc; | |
760 | $ld2pos = pos($$textref); | |
761 | return ( | |
762 | $startpos, $oppos-$startpos, # PREFIX | |
763 | $oppos, length($op), # OPERATOR | |
764 | $ld1pos, $extrapos-$ld1pos, # LEFT DEL | |
765 | $str1pos, $rd1pos-$str1pos, # STR/PAT | |
766 | $rd1pos, $ld2pos-$rd1pos, # RIGHT DEL | |
767 | $ld2pos, 0, # NO 2ND LDEL | |
768 | $ld2pos, 0, # NO 2ND STR | |
769 | $ld2pos, 0, # NO 2ND RDEL | |
770 | $ld2pos, 0, # NO MODIFIERS | |
771 | $ld2pos, $textlen-$ld2pos, # REMAINDER | |
772 | $extrapos, $str1pos-$extrapos, # FILLETED BIT | |
773 | ); | |
774 | } | |
775 | ||
776 | $$textref =~ m/\G\s*/gc; | |
777 | $ld1pos = pos($$textref); | |
778 | $str1pos = $ld1pos+1; | |
779 | ||
780 | unless ($$textref =~ m/\G(\S)/gc) # SHOULD USE LOOKAHEAD | |
781 | { | |
782 | _failmsg "No block delimiter found after quotelike $op", | |
783 | pos $$textref; | |
784 | pos $$textref = $startpos; | |
785 | return; | |
786 | } | |
787 | pos($$textref) = $ld1pos; # HAVE TO DO THIS BECAUSE LOOKAHEAD BROKEN | |
788 | my ($ldel1, $rdel1) = ("\Q$1","\Q$1"); | |
789 | if ($ldel1 =~ /[[(<{]/) | |
790 | { | |
791 | $rdel1 =~ tr/[({</])}>/; | |
792 | _match_bracketed($textref,"",$ldel1,"","",$rdel1) | |
793 | || do { pos $$textref = $startpos; return }; | |
794 | } | |
795 | else | |
796 | { | |
797 | $$textref =~ /$ldel1[^\\$ldel1]*(\\.[^\\$ldel1]*)*$ldel1/gcs | |
798 | || do { pos $$textref = $startpos; return }; | |
799 | } | |
800 | $ld2pos = $rd1pos = pos($$textref)-1; | |
801 | ||
802 | my $second_arg = $op =~ /s|tr|y/ ? 1 : 0; | |
803 | if ($second_arg) | |
804 | { | |
805 | my ($ldel2, $rdel2); | |
806 | if ($ldel1 =~ /[[(<{]/) | |
807 | { | |
808 | unless ($$textref =~ /\G\s*(\S)/gc) # SHOULD USE LOOKAHEAD | |
809 | { | |
810 | _failmsg "Missing second block for quotelike $op", | |
811 | pos $$textref; | |
812 | pos $$textref = $startpos; | |
813 | return; | |
814 | } | |
815 | $ldel2 = $rdel2 = "\Q$1"; | |
816 | $rdel2 =~ tr/[({</])}>/; | |
817 | } | |
818 | else | |
819 | { | |
820 | $ldel2 = $rdel2 = $ldel1; | |
821 | } | |
822 | $str2pos = $ld2pos+1; | |
823 | ||
824 | if ($ldel2 =~ /[[(<{]/) | |
825 | { | |
826 | pos($$textref)--; # OVERCOME BROKEN LOOKAHEAD | |
827 | _match_bracketed($textref,"",$ldel2,"","",$rdel2) | |
828 | || do { pos $$textref = $startpos; return }; | |
829 | } | |
830 | else | |
831 | { | |
832 | $$textref =~ /[^\\$ldel2]*(\\.[^\\$ldel2]*)*$ldel2/gcs | |
833 | || do { pos $$textref = $startpos; return }; | |
834 | } | |
835 | $rd2pos = pos($$textref)-1; | |
836 | } | |
837 | else | |
838 | { | |
839 | $ld2pos = $str2pos = $rd2pos = $rd1pos; | |
840 | } | |
841 | ||
842 | $modpos = pos $$textref; | |
843 | ||
844 | $$textref =~ m/\G($mods{$op})/gc; | |
845 | my $endpos = pos $$textref; | |
846 | ||
847 | return ( | |
848 | $startpos, $oppos-$startpos, # PREFIX | |
849 | $oppos, length($op), # OPERATOR | |
850 | $ld1pos, 1, # LEFT DEL | |
851 | $str1pos, $rd1pos-$str1pos, # STR/PAT | |
852 | $rd1pos, 1, # RIGHT DEL | |
853 | $ld2pos, $second_arg, # 2ND LDEL (MAYBE) | |
854 | $str2pos, $rd2pos-$str2pos, # 2ND STR (MAYBE) | |
855 | $rd2pos, $second_arg, # 2ND RDEL (MAYBE) | |
856 | $modpos, $endpos-$modpos, # MODIFIERS | |
857 | $endpos, $textlen-$endpos, # REMAINDER | |
858 | ); | |
859 | } | |
860 | ||
861 | my $def_func = | |
862 | [ | |
863 | sub { extract_variable($_[0], '') }, | |
864 | sub { extract_quotelike($_[0],'') }, | |
865 | sub { extract_codeblock($_[0],'{}','') }, | |
866 | ]; | |
867 | ||
868 | sub extract_multiple (;$$$$) # ($text, $functions_ref, $max_fields, $ignoreunknown) | |
869 | { | |
870 | my $textref = defined($_[0]) ? \$_[0] : \$_; | |
871 | my $posbug = pos; | |
872 | my ($lastpos, $firstpos); | |
873 | my @fields = (); | |
874 | ||
875 | #for ($$textref) | |
876 | { | |
877 | my @func = defined $_[1] ? @{$_[1]} : @{$def_func}; | |
878 | my $max = defined $_[2] && $_[2]>0 ? $_[2] : 1_000_000_000; | |
879 | my $igunk = $_[3]; | |
880 | ||
881 | pos $$textref ||= 0; | |
882 | ||
883 | unless (wantarray) | |
884 | { | |
885 | use Carp; | |
886 | carp "extract_multiple reset maximal count to 1 in scalar context" | |
887 | if $^W && defined($_[2]) && $max > 1; | |
888 | $max = 1 | |
889 | } | |
890 | ||
891 | my $unkpos; | |
892 | my $func; | |
893 | my $class; | |
894 | ||
895 | my @class; | |
896 | foreach $func ( @func ) | |
897 | { | |
898 | if (ref($func) eq 'HASH') | |
899 | { | |
900 | push @class, (keys %$func)[0]; | |
901 | $func = (values %$func)[0]; | |
902 | } | |
903 | else | |
904 | { | |
905 | push @class, undef; | |
906 | } | |
907 | } | |
908 | ||
909 | FIELD: while (pos($$textref) < length($$textref)) | |
910 | { | |
911 | my $field; | |
912 | my @bits; | |
913 | foreach my $i ( 0..$#func ) | |
914 | { | |
915 | my $pref; | |
916 | $func = $func[$i]; | |
917 | $class = $class[$i]; | |
918 | $lastpos = pos $$textref; | |
919 | if (ref($func) eq 'CODE') | |
920 | { ($field,undef,$pref) = @bits = $func->($$textref) } | |
921 | elsif (ref($func) eq 'Text::Balanced::Extractor') | |
922 | { @bits = $field = $func->extract($$textref) } | |
923 | elsif( $$textref =~ m/\G$func/gc ) | |
924 | { @bits = $field = defined($1) ? $1 : &$GetMatchedText($$textref) } | |
925 | # substr() on previous line is "$&", without the pain | |
926 | $pref ||= ""; | |
927 | if (defined($field) && length($field)) | |
928 | { | |
929 | if (!$igunk) { | |
930 | $unkpos = pos $$textref | |
931 | if length($pref) && !defined($unkpos); | |
932 | if (defined $unkpos) | |
933 | { | |
934 | push @fields, substr($$textref, $unkpos, $lastpos-$unkpos).$pref; | |
935 | $firstpos = $unkpos unless defined $firstpos; | |
936 | undef $unkpos; | |
937 | last FIELD if @fields == $max; | |
938 | } | |
939 | } | |
940 | push @fields, $class | |
941 | ? bless (\$field, $class) | |
942 | : $field; | |
943 | $firstpos = $lastpos unless defined $firstpos; | |
944 | $lastpos = pos $$textref; | |
945 | last FIELD if @fields == $max; | |
946 | next FIELD; | |
947 | } | |
948 | } | |
949 | if ($$textref =~ /\G(.)/gcs) | |
950 | { | |
951 | $unkpos = pos($$textref)-1 | |
952 | unless $igunk || defined $unkpos; | |
953 | } | |
954 | } | |
955 | ||
956 | if (defined $unkpos) | |
957 | { | |
958 | push @fields, substr($$textref, $unkpos); | |
959 | $firstpos = $unkpos unless defined $firstpos; | |
960 | $lastpos = length $$textref; | |
961 | } | |
962 | last; | |
963 | } | |
964 | ||
965 | pos $$textref = $lastpos; | |
966 | return @fields if wantarray; | |
967 | ||
968 | $firstpos ||= 0; | |
969 | eval { substr($$textref,$firstpos,$lastpos-$firstpos)=""; | |
970 | pos $$textref = $firstpos }; | |
971 | return $fields[0]; | |
972 | } | |
973 | ||
974 | ||
975 | sub gen_extract_tagged # ($opentag, $closetag, $pre, \%options) | |
976 | { | |
977 | my $ldel = $_[0]; | |
978 | my $rdel = $_[1]; | |
979 | my $pre = defined $_[2] ? $_[2] : '\s*'; | |
980 | my %options = defined $_[3] ? %{$_[3]} : (); | |
981 | my $omode = defined $options{fail} ? $options{fail} : ''; | |
982 | my $bad = ref($options{reject}) eq 'ARRAY' ? join('|', @{$options{reject}}) | |
983 | : defined($options{reject}) ? $options{reject} | |
984 | : '' | |
985 | ; | |
986 | my $ignore = ref($options{ignore}) eq 'ARRAY' ? join('|', @{$options{ignore}}) | |
987 | : defined($options{ignore}) ? $options{ignore} | |
988 | : '' | |
989 | ; | |
990 | ||
991 | if (!defined $ldel) { $ldel = '<\w+(?:' . gen_delimited_pat(q{'"}) . '|[^>])*>'; } | |
992 | ||
993 | my $posbug = pos; | |
994 | for ($ldel, $pre, $bad, $ignore) { $_ = qr/$_/ if $_ } | |
995 | pos = $posbug; | |
996 | ||
997 | my $closure = sub | |
998 | { | |
999 | my $textref = defined $_[0] ? \$_[0] : \$_; | |
1000 | my @match = Text::Balanced::_match_tagged($textref, $pre, $ldel, $rdel, $omode, $bad, $ignore); | |
1001 | ||
1002 | return _fail(wantarray, $textref) unless @match; | |
1003 | return _succeed wantarray, $textref, | |
1004 | $match[2], $match[3]+$match[5]+$match[7], # MATCH | |
1005 | @match[8..9,0..1,2..7]; # REM, PRE, BITS | |
1006 | }; | |
1007 | ||
1008 | bless $closure, 'Text::Balanced::Extractor'; | |
1009 | } | |
1010 | ||
1011 | package Text::Balanced::Extractor; | |
1012 | ||
1013 | sub extract($$) # ($self, $text) | |
1014 | { | |
1015 | &{$_[0]}($_[1]); | |
1016 | } | |
1017 | ||
1018 | package Text::Balanced::ErrorMsg; | |
1019 | ||
1020 | use overload '""' => sub { "$_[0]->{error}, detected at offset $_[0]->{pos}" }; | |
1021 | ||
1022 | 1; | |
1023 | ||
1024 | __END__ | |
1025 | ||
1026 | =head1 NAME | |
1027 | ||
1028 | Text::Balanced - Extract delimited text sequences from strings. | |
1029 | ||
1030 | ||
1031 | =head1 SYNOPSIS | |
1032 | ||
1033 | use Text::Balanced qw ( | |
1034 | extract_delimited | |
1035 | extract_bracketed | |
1036 | extract_quotelike | |
1037 | extract_codeblock | |
1038 | extract_variable | |
1039 | extract_tagged | |
1040 | extract_multiple | |
1041 | ||
1042 | gen_delimited_pat | |
1043 | gen_extract_tagged | |
1044 | ); | |
1045 | ||
1046 | # Extract the initial substring of $text that is delimited by | |
1047 | # two (unescaped) instances of the first character in $delim. | |
1048 | ||
1049 | ($extracted, $remainder) = extract_delimited($text,$delim); | |
1050 | ||
1051 | ||
1052 | # Extract the initial substring of $text that is bracketed | |
1053 | # with a delimiter(s) specified by $delim (where the string | |
1054 | # in $delim contains one or more of '(){}[]<>'). | |
1055 | ||
1056 | ($extracted, $remainder) = extract_bracketed($text,$delim); | |
1057 | ||
1058 | ||
1059 | # Extract the initial substring of $text that is bounded by | |
1060 | # an HTML/XML tag. | |
1061 | ||
1062 | ($extracted, $remainder) = extract_tagged($text); | |
1063 | ||
1064 | ||
1065 | # Extract the initial substring of $text that is bounded by | |
1066 | # a C<BEGIN>...C<END> pair. Don't allow nested C<BEGIN> tags | |
1067 | ||
1068 | ($extracted, $remainder) = | |
1069 | extract_tagged($text,"BEGIN","END",undef,{bad=>["BEGIN"]}); | |
1070 | ||
1071 | ||
1072 | # Extract the initial substring of $text that represents a | |
1073 | # Perl "quote or quote-like operation" | |
1074 | ||
1075 | ($extracted, $remainder) = extract_quotelike($text); | |
1076 | ||
1077 | ||
1078 | # Extract the initial substring of $text that represents a block | |
1079 | # of Perl code, bracketed by any of character(s) specified by $delim | |
1080 | # (where the string $delim contains one or more of '(){}[]<>'). | |
1081 | ||
1082 | ($extracted, $remainder) = extract_codeblock($text,$delim); | |
1083 | ||
1084 | ||
1085 | # Extract the initial substrings of $text that would be extracted by | |
1086 | # one or more sequential applications of the specified functions | |
1087 | # or regular expressions | |
1088 | ||
1089 | @extracted = extract_multiple($text, | |
1090 | [ \&extract_bracketed, | |
1091 | \&extract_quotelike, | |
1092 | \&some_other_extractor_sub, | |
1093 | qr/[xyz]*/, | |
1094 | 'literal', | |
1095 | ]); | |
1096 | ||
1097 | # Create a string representing an optimized pattern (a la Friedl) | |
1098 | # that matches a substring delimited by any of the specified characters | |
1099 | # (in this case: any type of quote or a slash) | |
1100 | ||
1101 | $patstring = gen_delimited_pat(q{'"`/}); | |
1102 | ||
1103 | ||
1104 | # Generate a reference to an anonymous sub that is just like extract_tagged | |
1105 | # but pre-compiled and optimized for a specific pair of tags, and consequently | |
1106 | # much faster (i.e. 3 times faster). It uses qr// for better performance on | |
1107 | # repeated calls, so it only works under Perl 5.005 or later. | |
1108 | ||
1109 | $extract_head = gen_extract_tagged('<HEAD>','</HEAD>'); | |
1110 | ||
1111 | ($extracted, $remainder) = $extract_head->($text); | |
1112 | ||
1113 | ||
1114 | =head1 DESCRIPTION | |
1115 | ||
1116 | The various C<extract_...> subroutines may be used to extract a | |
1117 | delimited string (possibly after skipping a specified prefix string). | |
1118 | The search for the string always begins at the current C<pos> | |
1119 | location of the string's variable (or at index zero, if no C<pos> | |
1120 | position is defined). | |
1121 | ||
1122 | =head2 General behaviour in list contexts | |
1123 | ||
1124 | In a list context, all the subroutines return a list, the first three | |
1125 | elements of which are always: | |
1126 | ||
1127 | =over 4 | |
1128 | ||
1129 | =item [0] | |
1130 | ||
1131 | The extracted string, including the specified delimiters. | |
1132 | If the extraction fails an empty string is returned. | |
1133 | ||
1134 | =item [1] | |
1135 | ||
1136 | The remainder of the input string (i.e. the characters after the | |
1137 | extracted string). On failure, the entire string is returned. | |
1138 | ||
1139 | =item [2] | |
1140 | ||
1141 | The skipped prefix (i.e. the characters before the extracted string). | |
1142 | On failure, the empty string is returned. | |
1143 | ||
1144 | =back | |
1145 | ||
1146 | Note that in a list context, the contents of the original input text (the first | |
1147 | argument) are not modified in any way. | |
1148 | ||
1149 | However, if the input text was passed in a variable, that variable's | |
1150 | C<pos> value is updated to point at the first character after the | |
1151 | extracted text. That means that in a list context the various | |
1152 | subroutines can be used much like regular expressions. For example: | |
1153 | ||
1154 | while ( $next = (extract_quotelike($text))[0] ) | |
1155 | { | |
1156 | # process next quote-like (in $next) | |
1157 | } | |
1158 | ||
1159 | ||
1160 | =head2 General behaviour in scalar and void contexts | |
1161 | ||
1162 | In a scalar context, the extracted string is returned, having first been | |
1163 | removed from the input text. Thus, the following code also processes | |
1164 | each quote-like operation, but actually removes them from $text: | |
1165 | ||
1166 | while ( $next = extract_quotelike($text) ) | |
1167 | { | |
1168 | # process next quote-like (in $next) | |
1169 | } | |
1170 | ||
1171 | Note that if the input text is a read-only string (i.e. a literal), | |
1172 | no attempt is made to remove the extracted text. | |
1173 | ||
1174 | In a void context the behaviour of the extraction subroutines is | |
1175 | exactly the same as in a scalar context, except (of course) that the | |
1176 | extracted substring is not returned. | |
1177 | ||
1178 | =head2 A note about prefixes | |
1179 | ||
1180 | Prefix patterns are matched without any trailing modifiers (C</gimsox> etc.) | |
1181 | This can bite you if you're expecting a prefix specification like | |
1182 | '.*?(?=<H1>)' to skip everything up to the first <H1> tag. Such a prefix | |
1183 | pattern will only succeed if the <H1> tag is on the current line, since | |
1184 | . normally doesn't match newlines. | |
1185 | ||
1186 | To overcome this limitation, you need to turn on /s matching within | |
1187 | the prefix pattern, using the C<(?s)> directive: '(?s).*?(?=<H1>)' | |
1188 | ||
1189 | ||
1190 | =head2 C<extract_delimited> | |
1191 | ||
1192 | The C<extract_delimited> function formalizes the common idiom | |
1193 | of extracting a single-character-delimited substring from the start of | |
1194 | a string. For example, to extract a single-quote delimited string, the | |
1195 | following code is typically used: | |
1196 | ||
1197 | ($remainder = $text) =~ s/\A('(\\.|[^'])*')//s; | |
1198 | $extracted = $1; | |
1199 | ||
1200 | but with C<extract_delimited> it can be simplified to: | |
1201 | ||
1202 | ($extracted,$remainder) = extract_delimited($text, "'"); | |
1203 | ||
1204 | C<extract_delimited> takes up to four scalars (the input text, the | |
1205 | delimiters, a prefix pattern to be skipped, and any escape characters) | |
1206 | and extracts the initial substring of the text that | |
1207 | is appropriately delimited. If the delimiter string has multiple | |
1208 | characters, the first one encountered in the text is taken to delimit | |
1209 | the substring. | |
1210 | The third argument specifies a prefix pattern that is to be skipped | |
1211 | (but must be present!) before the substring is extracted. | |
1212 | The final argument specifies the escape character to be used for each | |
1213 | delimiter. | |
1214 | ||
1215 | All arguments are optional. If the escape characters are not specified, | |
1216 | every delimiter is escaped with a backslash (C<\>). | |
1217 | If the prefix is not specified, the | |
1218 | pattern C<'\s*'> - optional whitespace - is used. If the delimiter set | |
1219 | is also not specified, the set C</["'`]/> is used. If the text to be processed | |
1220 | is not specified either, C<$_> is used. | |
1221 | ||
1222 | In list context, C<extract_delimited> returns an array of three | |
1223 | elements, the extracted substring (I<including the surrounding | |
1224 | delimiters>), the remainder of the text, and the skipped prefix (if | |
1225 | any). If a suitable delimited substring is not found, the first | |
1226 | element of the array is the empty string, the second is the complete | |
1227 | original text, and the prefix returned in the third element is an | |
1228 | empty string. | |
1229 | ||
1230 | In a scalar context, just the extracted substring is returned. In | |
1231 | a void context, the extracted substring (and any prefix) are simply | |
1232 | removed from the beginning of the first argument. | |
1233 | ||
1234 | Examples: | |
1235 | ||
1236 | # Remove a single-quoted substring from the very beginning of $text: | |
1237 | ||
1238 | $substring = extract_delimited($text, "'", ''); | |
1239 | ||
1240 | # Remove a single-quoted Pascalish substring (i.e. one in which | |
1241 | # doubling the quote character escapes it) from the very | |
1242 | # beginning of $text: | |
1243 | ||
1244 | $substring = extract_delimited($text, "'", '', "'"); | |
1245 | ||
1246 | # Extract a single- or double- quoted substring from the | |
1247 | # beginning of $text, optionally after some whitespace | |
1248 | # (note the list context to protect $text from modification): | |
1249 | ||
1250 | ($substring) = extract_delimited $text, q{"'}; | |
1251 | ||
1252 | ||
1253 | # Delete the substring delimited by the first '/' in $text: | |
1254 | ||
1255 | $text = join '', (extract_delimited($text,'/','[^/]*')[2,1]; | |
1256 | ||
1257 | Note that this last example is I<not> the same as deleting the first | |
1258 | quote-like pattern. For instance, if C<$text> contained the string: | |
1259 | ||
1260 | "if ('./cmd' =~ m/$UNIXCMD/s) { $cmd = $1; }" | |
1261 | ||
1262 | then after the deletion it would contain: | |
1263 | ||
1264 | "if ('.$UNIXCMD/s) { $cmd = $1; }" | |
1265 | ||
1266 | not: | |
1267 | ||
1268 | "if ('./cmd' =~ ms) { $cmd = $1; }" | |
1269 | ||
1270 | ||
1271 | See L<"extract_quotelike"> for a (partial) solution to this problem. | |
1272 | ||
1273 | ||
1274 | =head2 C<extract_bracketed> | |
1275 | ||
1276 | Like C<"extract_delimited">, the C<extract_bracketed> function takes | |
1277 | up to three optional scalar arguments: a string to extract from, a delimiter | |
1278 | specifier, and a prefix pattern. As before, a missing prefix defaults to | |
1279 | optional whitespace and a missing text defaults to C<$_>. However, a missing | |
1280 | delimiter specifier defaults to C<'{}()[]E<lt>E<gt>'> (see below). | |
1281 | ||
1282 | C<extract_bracketed> extracts a balanced-bracket-delimited | |
1283 | substring (using any one (or more) of the user-specified delimiter | |
1284 | brackets: '(..)', '{..}', '[..]', or '<..>'). Optionally it will also | |
1285 | respect quoted unbalanced brackets (see below). | |
1286 | ||
1287 | A "delimiter bracket" is a bracket in list of delimiters passed as | |
1288 | C<extract_bracketed>'s second argument. Delimiter brackets are | |
1289 | specified by giving either the left or right (or both!) versions | |
1290 | of the required bracket(s). Note that the order in which | |
1291 | two or more delimiter brackets are specified is not significant. | |
1292 | ||
1293 | A "balanced-bracket-delimited substring" is a substring bounded by | |
1294 | matched brackets, such that any other (left or right) delimiter | |
1295 | bracket I<within> the substring is also matched by an opposite | |
1296 | (right or left) delimiter bracket I<at the same level of nesting>. Any | |
1297 | type of bracket not in the delimiter list is treated as an ordinary | |
1298 | character. | |
1299 | ||
1300 | In other words, each type of bracket specified as a delimiter must be | |
1301 | balanced and correctly nested within the substring, and any other kind of | |
1302 | ("non-delimiter") bracket in the substring is ignored. | |
1303 | ||
1304 | For example, given the string: | |
1305 | ||
1306 | $text = "{ an '[irregularly :-(] {} parenthesized >:-)' string }"; | |
1307 | ||
1308 | then a call to C<extract_bracketed> in a list context: | |
1309 | ||
1310 | @result = extract_bracketed( $text, '{}' ); | |
1311 | ||
1312 | would return: | |
1313 | ||
1314 | ( "{ an '[irregularly :-(] {} parenthesized >:-)' string }" , "" , "" ) | |
1315 | ||
1316 | since both sets of C<'{..}'> brackets are properly nested and evenly balanced. | |
1317 | (In a scalar context just the first element of the array would be returned. In | |
1318 | a void context, C<$text> would be replaced by an empty string.) | |
1319 | ||
1320 | Likewise the call in: | |
1321 | ||
1322 | @result = extract_bracketed( $text, '{[' ); | |
1323 | ||
1324 | would return the same result, since all sets of both types of specified | |
1325 | delimiter brackets are correctly nested and balanced. | |
1326 | ||
1327 | However, the call in: | |
1328 | ||
1329 | @result = extract_bracketed( $text, '{([<' ); | |
1330 | ||
1331 | would fail, returning: | |
1332 | ||
1333 | ( undef , "{ an '[irregularly :-(] {} parenthesized >:-)' string }" ); | |
1334 | ||
1335 | because the embedded pairs of C<'(..)'>s and C<'[..]'>s are "cross-nested" and | |
1336 | the embedded C<'E<gt>'> is unbalanced. (In a scalar context, this call would | |
1337 | return an empty string. In a void context, C<$text> would be unchanged.) | |
1338 | ||
1339 | Note that the embedded single-quotes in the string don't help in this | |
1340 | case, since they have not been specified as acceptable delimiters and are | |
1341 | therefore treated as non-delimiter characters (and ignored). | |
1342 | ||
1343 | However, if a particular species of quote character is included in the | |
1344 | delimiter specification, then that type of quote will be correctly handled. | |
1345 | for example, if C<$text> is: | |
1346 | ||
1347 | $text = '<A HREF=">>>>">link</A>'; | |
1348 | ||
1349 | then | |
1350 | ||
1351 | @result = extract_bracketed( $text, '<">' ); | |
1352 | ||
1353 | returns: | |
1354 | ||
1355 | ( '<A HREF=">>>>">', 'link</A>', "" ) | |
1356 | ||
1357 | as expected. Without the specification of C<"> as an embedded quoter: | |
1358 | ||
1359 | @result = extract_bracketed( $text, '<>' ); | |
1360 | ||
1361 | the result would be: | |
1362 | ||
1363 | ( '<A HREF=">', '>>>">link</A>', "" ) | |
1364 | ||
1365 | In addition to the quote delimiters C<'>, C<">, and C<`>, full Perl quote-like | |
1366 | quoting (i.e. q{string}, qq{string}, etc) can be specified by including the | |
1367 | letter 'q' as a delimiter. Hence: | |
1368 | ||
1369 | @result = extract_bracketed( $text, '<q>' ); | |
1370 | ||
1371 | would correctly match something like this: | |
1372 | ||
1373 | $text = '<leftop: conj /and/ conj>'; | |
1374 | ||
1375 | See also: C<"extract_quotelike"> and C<"extract_codeblock">. | |
1376 | ||
1377 | ||
1378 | =head2 C<extract_tagged> | |
1379 | ||
1380 | C<extract_tagged> extracts and segments text between (balanced) | |
1381 | specified tags. | |
1382 | ||
1383 | The subroutine takes up to five optional arguments: | |
1384 | ||
1385 | =over 4 | |
1386 | ||
1387 | =item 1. | |
1388 | ||
1389 | A string to be processed (C<$_> if the string is omitted or C<undef>) | |
1390 | ||
1391 | =item 2. | |
1392 | ||
1393 | A string specifying a pattern to be matched as the opening tag. | |
1394 | If the pattern string is omitted (or C<undef>) then a pattern | |
1395 | that matches any standard HTML/XML tag is used. | |
1396 | ||
1397 | =item 3. | |
1398 | ||
1399 | A string specifying a pattern to be matched at the closing tag. | |
1400 | If the pattern string is omitted (or C<undef>) then the closing | |
1401 | tag is constructed by inserting a C</> after any leading bracket | |
1402 | characters in the actual opening tag that was matched (I<not> the pattern | |
1403 | that matched the tag). For example, if the opening tag pattern | |
1404 | is specified as C<'{{\w+}}'> and actually matched the opening tag | |
1405 | C<"{{DATA}}">, then the constructed closing tag would be C<"{{/DATA}}">. | |
1406 | ||
1407 | =item 4. | |
1408 | ||
1409 | A string specifying a pattern to be matched as a prefix (which is to be | |
1410 | skipped). If omitted, optional whitespace is skipped. | |
1411 | ||
1412 | =item 5. | |
1413 | ||
1414 | A hash reference containing various parsing options (see below) | |
1415 | ||
1416 | =back | |
1417 | ||
1418 | The various options that can be specified are: | |
1419 | ||
1420 | =over 4 | |
1421 | ||
1422 | =item C<reject =E<gt> $listref> | |
1423 | ||
1424 | The list reference contains one or more strings specifying patterns | |
1425 | that must I<not> appear within the tagged text. | |
1426 | ||
1427 | For example, to extract | |
1428 | an HTML link (which should not contain nested links) use: | |
1429 | ||
1430 | extract_tagged($text, '<A>', '</A>', undef, {reject => ['<A>']} ); | |
1431 | ||
1432 | =item C<ignore =E<gt> $listref> | |
1433 | ||
1434 | The list reference contains one or more strings specifying patterns | |
1435 | that are I<not> be be treated as nested tags within the tagged text | |
1436 | (even if they would match the start tag pattern). | |
1437 | ||
1438 | For example, to extract an arbitrary XML tag, but ignore "empty" elements: | |
1439 | ||
1440 | extract_tagged($text, undef, undef, undef, {ignore => ['<[^>]*/>']} ); | |
1441 | ||
1442 | (also see L<"gen_delimited_pat"> below). | |
1443 | ||
1444 | ||
1445 | =item C<fail =E<gt> $str> | |
1446 | ||
1447 | The C<fail> option indicates the action to be taken if a matching end | |
1448 | tag is not encountered (i.e. before the end of the string or some | |
1449 | C<reject> pattern matches). By default, a failure to match a closing | |
1450 | tag causes C<extract_tagged> to immediately fail. | |
1451 | ||
1452 | However, if the string value associated with <reject> is "MAX", then | |
1453 | C<extract_tagged> returns the complete text up to the point of failure. | |
1454 | If the string is "PARA", C<extract_tagged> returns only the first paragraph | |
1455 | after the tag (up to the first line that is either empty or contains | |
1456 | only whitespace characters). | |
1457 | If the string is "", the default behaviour (i.e. failure) is reinstated. | |
1458 | ||
1459 | For example, suppose the start tag "/para" introduces a paragraph, which then | |
1460 | continues until the next "/endpara" tag or until another "/para" tag is | |
1461 | encountered: | |
1462 | ||
1463 | $text = "/para line 1\n\nline 3\n/para line 4"; | |
1464 | ||
1465 | extract_tagged($text, '/para', '/endpara', undef, | |
1466 | {reject => '/para', fail => MAX ); | |
1467 | ||
1468 | # EXTRACTED: "/para line 1\n\nline 3\n" | |
1469 | ||
1470 | Suppose instead, that if no matching "/endpara" tag is found, the "/para" | |
1471 | tag refers only to the immediately following paragraph: | |
1472 | ||
1473 | $text = "/para line 1\n\nline 3\n/para line 4"; | |
1474 | ||
1475 | extract_tagged($text, '/para', '/endpara', undef, | |
1476 | {reject => '/para', fail => MAX ); | |
1477 | ||
1478 | # EXTRACTED: "/para line 1\n" | |
1479 | ||
1480 | Note that the specified C<fail> behaviour applies to nested tags as well. | |
1481 | ||
1482 | =back | |
1483 | ||
1484 | On success in a list context, an array of 6 elements is returned. The elements are: | |
1485 | ||
1486 | =over 4 | |
1487 | ||
1488 | =item [0] | |
1489 | ||
1490 | the extracted tagged substring (including the outermost tags), | |
1491 | ||
1492 | =item [1] | |
1493 | ||
1494 | the remainder of the input text, | |
1495 | ||
1496 | =item [2] | |
1497 | ||
1498 | the prefix substring (if any), | |
1499 | ||
1500 | =item [3] | |
1501 | ||
1502 | the opening tag | |
1503 | ||
1504 | =item [4] | |
1505 | ||
1506 | the text between the opening and closing tags | |
1507 | ||
1508 | =item [5] | |
1509 | ||
1510 | the closing tag (or "" if no closing tag was found) | |
1511 | ||
1512 | =back | |
1513 | ||
1514 | On failure, all of these values (except the remaining text) are C<undef>. | |
1515 | ||
1516 | In a scalar context, C<extract_tagged> returns just the complete | |
1517 | substring that matched a tagged text (including the start and end | |
1518 | tags). C<undef> is returned on failure. In addition, the original input | |
1519 | text has the returned substring (and any prefix) removed from it. | |
1520 | ||
1521 | In a void context, the input text just has the matched substring (and | |
1522 | any specified prefix) removed. | |
1523 | ||
1524 | ||
1525 | =head2 C<gen_extract_tagged> | |
1526 | ||
1527 | (Note: This subroutine is only available under Perl5.005) | |
1528 | ||
1529 | C<gen_extract_tagged> generates a new anonymous subroutine which | |
1530 | extracts text between (balanced) specified tags. In other words, | |
1531 | it generates a function identical in function to C<extract_tagged>. | |
1532 | ||
1533 | The difference between C<extract_tagged> and the anonymous | |
1534 | subroutines generated by | |
1535 | C<gen_extract_tagged>, is that those generated subroutines: | |
1536 | ||
1537 | =over 4 | |
1538 | ||
1539 | =item * | |
1540 | ||
1541 | do not have to reparse tag specification or parsing options every time | |
1542 | they are called (whereas C<extract_tagged> has to effectively rebuild | |
1543 | its tag parser on every call); | |
1544 | ||
1545 | =item * | |
1546 | ||
1547 | make use of the new qr// construct to pre-compile the regexes they use | |
1548 | (whereas C<extract_tagged> uses standard string variable interpolation | |
1549 | to create tag-matching patterns). | |
1550 | ||
1551 | =back | |
1552 | ||
1553 | The subroutine takes up to four optional arguments (the same set as | |
1554 | C<extract_tagged> except for the string to be processed). It returns | |
1555 | a reference to a subroutine which in turn takes a single argument (the text to | |
1556 | be extracted from). | |
1557 | ||
1558 | In other words, the implementation of C<extract_tagged> is exactly | |
1559 | equivalent to: | |
1560 | ||
1561 | sub extract_tagged | |
1562 | { | |
1563 | my $text = shift; | |
1564 | $extractor = gen_extract_tagged(@_); | |
1565 | return $extractor->($text); | |
1566 | } | |
1567 | ||
1568 | (although C<extract_tagged> is not currently implemented that way, in order | |
1569 | to preserve pre-5.005 compatibility). | |
1570 | ||
1571 | Using C<gen_extract_tagged> to create extraction functions for specific tags | |
1572 | is a good idea if those functions are going to be called more than once, since | |
1573 | their performance is typically twice as good as the more general-purpose | |
1574 | C<extract_tagged>. | |
1575 | ||
1576 | ||
1577 | =head2 C<extract_quotelike> | |
1578 | ||
1579 | C<extract_quotelike> attempts to recognize, extract, and segment any | |
1580 | one of the various Perl quotes and quotelike operators (see | |
1581 | L<perlop(3)>) Nested backslashed delimiters, embedded balanced bracket | |
1582 | delimiters (for the quotelike operators), and trailing modifiers are | |
1583 | all caught. For example, in: | |
1584 | ||
1585 | extract_quotelike 'q # an octothorpe: \# (not the end of the q!) #' | |
1586 | ||
1587 | extract_quotelike ' "You said, \"Use sed\"." ' | |
1588 | ||
1589 | extract_quotelike ' s{([A-Z]{1,8}\.[A-Z]{3})} /\L$1\E/; ' | |
1590 | ||
1591 | extract_quotelike ' tr/\\\/\\\\/\\\//ds; ' | |
1592 | ||
1593 | the full Perl quotelike operations are all extracted correctly. | |
1594 | ||
1595 | Note too that, when using the /x modifier on a regex, any comment | |
1596 | containing the current pattern delimiter will cause the regex to be | |
1597 | immediately terminated. In other words: | |
1598 | ||
1599 | 'm / | |
1600 | (?i) # CASE INSENSITIVE | |
1601 | [a-z_] # LEADING ALPHABETIC/UNDERSCORE | |
1602 | [a-z0-9]* # FOLLOWED BY ANY NUMBER OF ALPHANUMERICS | |
1603 | /x' | |
1604 | ||
1605 | will be extracted as if it were: | |
1606 | ||
1607 | 'm / | |
1608 | (?i) # CASE INSENSITIVE | |
1609 | [a-z_] # LEADING ALPHABETIC/' | |
1610 | ||
1611 | This behaviour is identical to that of the actual compiler. | |
1612 | ||
1613 | C<extract_quotelike> takes two arguments: the text to be processed and | |
1614 | a prefix to be matched at the very beginning of the text. If no prefix | |
1615 | is specified, optional whitespace is the default. If no text is given, | |
1616 | C<$_> is used. | |
1617 | ||
1618 | In a list context, an array of 11 elements is returned. The elements are: | |
1619 | ||
1620 | =over 4 | |
1621 | ||
1622 | =item [0] | |
1623 | ||
1624 | the extracted quotelike substring (including trailing modifiers), | |
1625 | ||
1626 | =item [1] | |
1627 | ||
1628 | the remainder of the input text, | |
1629 | ||
1630 | =item [2] | |
1631 | ||
1632 | the prefix substring (if any), | |
1633 | ||
1634 | =item [3] | |
1635 | ||
1636 | the name of the quotelike operator (if any), | |
1637 | ||
1638 | =item [4] | |
1639 | ||
1640 | the left delimiter of the first block of the operation, | |
1641 | ||
1642 | =item [5] | |
1643 | ||
1644 | the text of the first block of the operation | |
1645 | (that is, the contents of | |
1646 | a quote, the regex of a match or substitution or the target list of a | |
1647 | translation), | |
1648 | ||
1649 | =item [6] | |
1650 | ||
1651 | the right delimiter of the first block of the operation, | |
1652 | ||
1653 | =item [7] | |
1654 | ||
1655 | the left delimiter of the second block of the operation | |
1656 | (that is, if it is an C<s>, C<tr>, or C<y>), | |
1657 | ||
1658 | =item [8] | |
1659 | ||
1660 | the text of the second block of the operation | |
1661 | (that is, the replacement of a substitution or the translation list | |
1662 | of a translation), | |
1663 | ||
1664 | =item [9] | |
1665 | ||
1666 | the right delimiter of the second block of the operation (if any), | |
1667 | ||
1668 | =item [10] | |
1669 | ||
1670 | the trailing modifiers on the operation (if any). | |
1671 | ||
1672 | =back | |
1673 | ||
1674 | For each of the fields marked "(if any)" the default value on success is | |
1675 | an empty string. | |
1676 | On failure, all of these values (except the remaining text) are C<undef>. | |
1677 | ||
1678 | ||
1679 | In a scalar context, C<extract_quotelike> returns just the complete substring | |
1680 | that matched a quotelike operation (or C<undef> on failure). In a scalar or | |
1681 | void context, the input text has the same substring (and any specified | |
1682 | prefix) removed. | |
1683 | ||
1684 | Examples: | |
1685 | ||
1686 | # Remove the first quotelike literal that appears in text | |
1687 | ||
1688 | $quotelike = extract_quotelike($text,'.*?'); | |
1689 | ||
1690 | # Replace one or more leading whitespace-separated quotelike | |
1691 | # literals in $_ with "<QLL>" | |
1692 | ||
1693 | do { $_ = join '<QLL>', (extract_quotelike)[2,1] } until $@; | |
1694 | ||
1695 | ||
1696 | # Isolate the search pattern in a quotelike operation from $text | |
1697 | ||
1698 | ($op,$pat) = (extract_quotelike $text)[3,5]; | |
1699 | if ($op =~ /[ms]/) | |
1700 | { | |
1701 | print "search pattern: $pat\n"; | |
1702 | } | |
1703 | else | |
1704 | { | |
1705 | print "$op is not a pattern matching operation\n"; | |
1706 | } | |
1707 | ||
1708 | ||
1709 | =head2 C<extract_quotelike> and "here documents" | |
1710 | ||
1711 | C<extract_quotelike> can successfully extract "here documents" from an input | |
1712 | string, but with an important caveat in list contexts. | |
1713 | ||
1714 | Unlike other types of quote-like literals, a here document is rarely | |
1715 | a contiguous substring. For example, a typical piece of code using | |
1716 | here document might look like this: | |
1717 | ||
1718 | <<'EOMSG' || die; | |
1719 | This is the message. | |
1720 | EOMSG | |
1721 | exit; | |
1722 | ||
1723 | Given this as an input string in a scalar context, C<extract_quotelike> | |
1724 | would correctly return the string "<<'EOMSG'\nThis is the message.\nEOMSG", | |
1725 | leaving the string " || die;\nexit;" in the original variable. In other words, | |
1726 | the two separate pieces of the here document are successfully extracted and | |
1727 | concatenated. | |
1728 | ||
1729 | In a list context, C<extract_quotelike> would return the list | |
1730 | ||
1731 | =over 4 | |
1732 | ||
1733 | =item [0] | |
1734 | ||
1735 | "<<'EOMSG'\nThis is the message.\nEOMSG\n" (i.e. the full extracted here document, | |
1736 | including fore and aft delimiters), | |
1737 | ||
1738 | =item [1] | |
1739 | ||
1740 | " || die;\nexit;" (i.e. the remainder of the input text, concatenated), | |
1741 | ||
1742 | =item [2] | |
1743 | ||
1744 | "" (i.e. the prefix substring -- trivial in this case), | |
1745 | ||
1746 | =item [3] | |
1747 | ||
1748 | "<<" (i.e. the "name" of the quotelike operator) | |
1749 | ||
1750 | =item [4] | |
1751 | ||
1752 | "'EOMSG'" (i.e. the left delimiter of the here document, including any quotes), | |
1753 | ||
1754 | =item [5] | |
1755 | ||
1756 | "This is the message.\n" (i.e. the text of the here document), | |
1757 | ||
1758 | =item [6] | |
1759 | ||
1760 | "EOMSG" (i.e. the right delimiter of the here document), | |
1761 | ||
1762 | =item [7..10] | |
1763 | ||
1764 | "" (a here document has no second left delimiter, second text, second right | |
1765 | delimiter, or trailing modifiers). | |
1766 | ||
1767 | =back | |
1768 | ||
1769 | However, the matching position of the input variable would be set to | |
1770 | "exit;" (i.e. I<after> the closing delimiter of the here document), | |
1771 | which would cause the earlier " || die;\nexit;" to be skipped in any | |
1772 | sequence of code fragment extractions. | |
1773 | ||
1774 | To avoid this problem, when it encounters a here document while | |
1775 | extracting from a modifiable string, C<extract_quotelike> silently | |
1776 | rearranges the string to an equivalent piece of Perl: | |
1777 | ||
1778 | <<'EOMSG' | |
1779 | This is the message. | |
1780 | EOMSG | |
1781 | || die; | |
1782 | exit; | |
1783 | ||
1784 | in which the here document I<is> contiguous. It still leaves the | |
1785 | matching position after the here document, but now the rest of the line | |
1786 | on which the here document starts is not skipped. | |
1787 | ||
1788 | To prevent <extract_quotelike> from mucking about with the input in this way | |
1789 | (this is the only case where a list-context C<extract_quotelike> does so), | |
1790 | you can pass the input variable as an interpolated literal: | |
1791 | ||
1792 | $quotelike = extract_quotelike("$var"); | |
1793 | ||
1794 | ||
1795 | =head2 C<extract_codeblock> | |
1796 | ||
1797 | C<extract_codeblock> attempts to recognize and extract a balanced | |
1798 | bracket delimited substring that may contain unbalanced brackets | |
1799 | inside Perl quotes or quotelike operations. That is, C<extract_codeblock> | |
1800 | is like a combination of C<"extract_bracketed"> and | |
1801 | C<"extract_quotelike">. | |
1802 | ||
1803 | C<extract_codeblock> takes the same initial three parameters as C<extract_bracketed>: | |
1804 | a text to process, a set of delimiter brackets to look for, and a prefix to | |
1805 | match first. It also takes an optional fourth parameter, which allows the | |
1806 | outermost delimiter brackets to be specified separately (see below). | |
1807 | ||
1808 | Omitting the first argument (input text) means process C<$_> instead. | |
1809 | Omitting the second argument (delimiter brackets) indicates that only C<'{'> is to be used. | |
1810 | Omitting the third argument (prefix argument) implies optional whitespace at the start. | |
1811 | Omitting the fourth argument (outermost delimiter brackets) indicates that the | |
1812 | value of the second argument is to be used for the outermost delimiters. | |
1813 | ||
1814 | Once the prefix an the outermost opening delimiter bracket have been | |
1815 | recognized, code blocks are extracted by stepping through the input text and | |
1816 | trying the following alternatives in sequence: | |
1817 | ||
1818 | =over 4 | |
1819 | ||
1820 | =item 1. | |
1821 | ||
1822 | Try and match a closing delimiter bracket. If the bracket was the same | |
1823 | species as the last opening bracket, return the substring to that | |
1824 | point. If the bracket was mismatched, return an error. | |
1825 | ||
1826 | =item 2. | |
1827 | ||
1828 | Try to match a quote or quotelike operator. If found, call | |
1829 | C<extract_quotelike> to eat it. If C<extract_quotelike> fails, return | |
1830 | the error it returned. Otherwise go back to step 1. | |
1831 | ||
1832 | =item 3. | |
1833 | ||
1834 | Try to match an opening delimiter bracket. If found, call | |
1835 | C<extract_codeblock> recursively to eat the embedded block. If the | |
1836 | recursive call fails, return an error. Otherwise, go back to step 1. | |
1837 | ||
1838 | =item 4. | |
1839 | ||
1840 | Unconditionally match a bareword or any other single character, and | |
1841 | then go back to step 1. | |
1842 | ||
1843 | =back | |
1844 | ||
1845 | ||
1846 | Examples: | |
1847 | ||
1848 | # Find a while loop in the text | |
1849 | ||
1850 | if ($text =~ s/.*?while\s*\{/{/) | |
1851 | { | |
1852 | $loop = "while " . extract_codeblock($text); | |
1853 | } | |
1854 | ||
1855 | # Remove the first round-bracketed list (which may include | |
1856 | # round- or curly-bracketed code blocks or quotelike operators) | |
1857 | ||
1858 | extract_codeblock $text, "(){}", '[^(]*'; | |
1859 | ||
1860 | ||
1861 | The ability to specify a different outermost delimiter bracket is useful | |
1862 | in some circumstances. For example, in the Parse::RecDescent module, | |
1863 | parser actions which are to be performed only on a successful parse | |
1864 | are specified using a C<E<lt>defer:...E<gt>> directive. For example: | |
1865 | ||
1866 | sentence: subject verb object | |
1867 | <defer: {$::theVerb = $item{verb}} > | |
1868 | ||
1869 | Parse::RecDescent uses C<extract_codeblock($text, '{}E<lt>E<gt>')> to extract the code | |
1870 | within the C<E<lt>defer:...E<gt>> directive, but there's a problem. | |
1871 | ||
1872 | A deferred action like this: | |
1873 | ||
1874 | <defer: {if ($count>10) {$count--}} > | |
1875 | ||
1876 | will be incorrectly parsed as: | |
1877 | ||
1878 | <defer: {if ($count> | |
1879 | ||
1880 | because the "less than" operator is interpreted as a closing delimiter. | |
1881 | ||
1882 | But, by extracting the directive using | |
1883 | S<C<extract_codeblock($text, '{}', undef, 'E<lt>E<gt>')>> | |
1884 | the '>' character is only treated as a delimited at the outermost | |
1885 | level of the code block, so the directive is parsed correctly. | |
1886 | ||
1887 | =head2 C<extract_multiple> | |
1888 | ||
1889 | The C<extract_multiple> subroutine takes a string to be processed and a | |
1890 | list of extractors (subroutines or regular expressions) to apply to that string. | |
1891 | ||
1892 | In an array context C<extract_multiple> returns an array of substrings | |
1893 | of the original string, as extracted by the specified extractors. | |
1894 | In a scalar context, C<extract_multiple> returns the first | |
1895 | substring successfully extracted from the original string. In both | |
1896 | scalar and void contexts the original string has the first successfully | |
1897 | extracted substring removed from it. In all contexts | |
1898 | C<extract_multiple> starts at the current C<pos> of the string, and | |
1899 | sets that C<pos> appropriately after it matches. | |
1900 | ||
1901 | Hence, the aim of a call to C<extract_multiple> in a list context | |
1902 | is to split the processed string into as many non-overlapping fields as | |
1903 | possible, by repeatedly applying each of the specified extractors | |
1904 | to the remainder of the string. Thus C<extract_multiple> is | |
1905 | a generalized form of Perl's C<split> subroutine. | |
1906 | ||
1907 | The subroutine takes up to four optional arguments: | |
1908 | ||
1909 | =over 4 | |
1910 | ||
1911 | =item 1. | |
1912 | ||
1913 | A string to be processed (C<$_> if the string is omitted or C<undef>) | |
1914 | ||
1915 | =item 2. | |
1916 | ||
1917 | A reference to a list of subroutine references and/or qr// objects and/or | |
1918 | literal strings and/or hash references, specifying the extractors | |
1919 | to be used to split the string. If this argument is omitted (or | |
1920 | C<undef>) the list: | |
1921 | ||
1922 | [ | |
1923 | sub { extract_variable($_[0], '') }, | |
1924 | sub { extract_quotelike($_[0],'') }, | |
1925 | sub { extract_codeblock($_[0],'{}','') }, | |
1926 | ] | |
1927 | ||
1928 | is used. | |
1929 | ||
1930 | ||
1931 | =item 3. | |
1932 | ||
1933 | A number specifying the maximum number of fields to return. If this | |
1934 | argument is omitted (or C<undef>), split continues as long as possible. | |
1935 | ||
1936 | If the third argument is I<N>, then extraction continues until I<N> fields | |
1937 | have been successfully extracted, or until the string has been completely | |
1938 | processed. | |
1939 | ||
1940 | Note that in scalar and void contexts the value of this argument is | |
1941 | automatically reset to 1 (under C<-w>, a warning is issued if the argument | |
1942 | has to be reset). | |
1943 | ||
1944 | =item 4. | |
1945 | ||
1946 | A value indicating whether unmatched substrings (see below) within the | |
1947 | text should be skipped or returned as fields. If the value is true, | |
1948 | such substrings are skipped. Otherwise, they are returned. | |
1949 | ||
1950 | =back | |
1951 | ||
1952 | The extraction process works by applying each extractor in | |
1953 | sequence to the text string. | |
1954 | ||
1955 | If the extractor is a subroutine it is called in a list context and is | |
1956 | expected to return a list of a single element, namely the extracted | |
1957 | text. It may optionally also return two further arguments: a string | |
1958 | representing the text left after extraction (like $' for a pattern | |
1959 | match), and a string representing any prefix skipped before the | |
1960 | extraction (like $` in a pattern match). Note that this is designed | |
1961 | to facilitate the use of other Text::Balanced subroutines with | |
1962 | C<extract_multiple>. Note too that the value returned by an extractor | |
1963 | subroutine need not bear any relationship to the corresponding substring | |
1964 | of the original text (see examples below). | |
1965 | ||
1966 | If the extractor is a precompiled regular expression or a string, | |
1967 | it is matched against the text in a scalar context with a leading | |
1968 | '\G' and the gc modifiers enabled. The extracted value is either | |
1969 | $1 if that variable is defined after the match, or else the | |
1970 | complete match (i.e. $&). | |
1971 | ||
1972 | If the extractor is a hash reference, it must contain exactly one element. | |
1973 | The value of that element is one of the | |
1974 | above extractor types (subroutine reference, regular expression, or string). | |
1975 | The key of that element is the name of a class into which the successful | |
1976 | return value of the extractor will be blessed. | |
1977 | ||
1978 | If an extractor returns a defined value, that value is immediately | |
1979 | treated as the next extracted field and pushed onto the list of fields. | |
1980 | If the extractor was specified in a hash reference, the field is also | |
1981 | blessed into the appropriate class, | |
1982 | ||
1983 | If the extractor fails to match (in the case of a regex extractor), or returns an empty list or an undefined value (in the case of a subroutine extractor), it is | |
1984 | assumed to have failed to extract. | |
1985 | If none of the extractor subroutines succeeds, then one | |
1986 | character is extracted from the start of the text and the extraction | |
1987 | subroutines reapplied. Characters which are thus removed are accumulated and | |
1988 | eventually become the next field (unless the fourth argument is true, in which | |
1989 | case they are discarded). | |
1990 | ||
1991 | For example, the following extracts substrings that are valid Perl variables: | |
1992 | ||
1993 | @fields = extract_multiple($text, | |
1994 | [ sub { extract_variable($_[0]) } ], | |
1995 | undef, 1); | |
1996 | ||
1997 | This example separates a text into fields which are quote delimited, | |
1998 | curly bracketed, and anything else. The delimited and bracketed | |
1999 | parts are also blessed to identify them (the "anything else" is unblessed): | |
2000 | ||
2001 | @fields = extract_multiple($text, | |
2002 | [ | |
2003 | { Delim => sub { extract_delimited($_[0],q{'"}) } }, | |
2004 | { Brack => sub { extract_bracketed($_[0],'{}') } }, | |
2005 | ]); | |
2006 | ||
2007 | This call extracts the next single substring that is a valid Perl quotelike | |
2008 | operator (and removes it from $text): | |
2009 | ||
2010 | $quotelike = extract_multiple($text, | |
2011 | [ | |
2012 | sub { extract_quotelike($_[0]) }, | |
2013 | ], undef, 1); | |
2014 | ||
2015 | Finally, here is yet another way to do comma-separated value parsing: | |
2016 | ||
2017 | @fields = extract_multiple($csv_text, | |
2018 | [ | |
2019 | sub { extract_delimited($_[0],q{'"}) }, | |
2020 | qr/([^,]+)(.*)/, | |
2021 | ], | |
2022 | undef,1); | |
2023 | ||
2024 | The list in the second argument means: | |
2025 | I<"Try and extract a ' or " delimited string, otherwise extract anything up to a comma...">. | |
2026 | The undef third argument means: | |
2027 | I<"...as many times as possible...">, | |
2028 | and the true value in the fourth argument means | |
2029 | I<"...discarding anything else that appears (i.e. the commas)">. | |
2030 | ||
2031 | If you wanted the commas preserved as separate fields (i.e. like split | |
2032 | does if your split pattern has capturing parentheses), you would | |
2033 | just make the last parameter undefined (or remove it). | |
2034 | ||
2035 | ||
2036 | =head2 C<gen_delimited_pat> | |
2037 | ||
2038 | The C<gen_delimited_pat> subroutine takes a single (string) argument and | |
2039 | > builds a Friedl-style optimized regex that matches a string delimited | |
2040 | by any one of the characters in the single argument. For example: | |
2041 | ||
2042 | gen_delimited_pat(q{'"}) | |
2043 | ||
2044 | returns the regex: | |
2045 | ||
2046 | (?:\"(?:\\\"|(?!\").)*\"|\'(?:\\\'|(?!\').)*\') | |
2047 | ||
2048 | Note that the specified delimiters are automatically quotemeta'd. | |
2049 | ||
2050 | A typical use of C<gen_delimited_pat> would be to build special purpose tags | |
2051 | for C<extract_tagged>. For example, to properly ignore "empty" XML elements | |
2052 | (which might contain quoted strings): | |
2053 | ||
2054 | my $empty_tag = '<(' . gen_delimited_pat(q{'"}) . '|.)+/>'; | |
2055 | ||
2056 | extract_tagged($text, undef, undef, undef, {ignore => [$empty_tag]} ); | |
2057 | ||
2058 | ||
2059 | C<gen_delimited_pat> may also be called with an optional second argument, | |
2060 | which specifies the "escape" character(s) to be used for each delimiter. | |
2061 | For example to match a Pascal-style string (where ' is the delimiter | |
2062 | and '' is a literal ' within the string): | |
2063 | ||
2064 | gen_delimited_pat(q{'},q{'}); | |
2065 | ||
2066 | Different escape characters can be specified for different delimiters. | |
2067 | For example, to specify that '/' is the escape for single quotes | |
2068 | and '%' is the escape for double quotes: | |
2069 | ||
2070 | gen_delimited_pat(q{'"},q{/%}); | |
2071 | ||
2072 | If more delimiters than escape chars are specified, the last escape char | |
2073 | is used for the remaining delimiters. | |
2074 | If no escape char is specified for a given specified delimiter, '\' is used. | |
2075 | ||
2076 | Note that | |
2077 | C<gen_delimited_pat> was previously called | |
2078 | C<delimited_pat>. That name may still be used, but is now deprecated. | |
2079 | ||
2080 | ||
2081 | =head1 DIAGNOSTICS | |
2082 | ||
2083 | In a list context, all the functions return C<(undef,$original_text)> | |
2084 | on failure. In a scalar context, failure is indicated by returning C<undef> | |
2085 | (in this case the input text is not modified in any way). | |
2086 | ||
2087 | In addition, on failure in I<any> context, the C<$@> variable is set. | |
2088 | Accessing C<$@-E<gt>{error}> returns one of the error diagnostics listed | |
2089 | below. | |
2090 | Accessing C<$@-E<gt>{pos}> returns the offset into the original string at | |
2091 | which the error was detected (although not necessarily where it occurred!) | |
2092 | Printing C<$@> directly produces the error message, with the offset appended. | |
2093 | On success, the C<$@> variable is guaranteed to be C<undef>. | |
2094 | ||
2095 | The available diagnostics are: | |
2096 | ||
2097 | =over 4 | |
2098 | ||
2099 | =item C<Did not find a suitable bracket: "%s"> | |
2100 | ||
2101 | The delimiter provided to C<extract_bracketed> was not one of | |
2102 | C<'()[]E<lt>E<gt>{}'>. | |
2103 | ||
2104 | =item C<Did not find prefix: /%s/> | |
2105 | ||
2106 | A non-optional prefix was specified but wasn't found at the start of the text. | |
2107 | ||
2108 | =item C<Did not find opening bracket after prefix: "%s"> | |
2109 | ||
2110 | C<extract_bracketed> or C<extract_codeblock> was expecting a | |
2111 | particular kind of bracket at the start of the text, and didn't find it. | |
2112 | ||
2113 | =item C<No quotelike operator found after prefix: "%s"> | |
2114 | ||
2115 | C<extract_quotelike> didn't find one of the quotelike operators C<q>, | |
2116 | C<qq>, C<qw>, C<qx>, C<s>, C<tr> or C<y> at the start of the substring | |
2117 | it was extracting. | |
2118 | ||
2119 | =item C<Unmatched closing bracket: "%c"> | |
2120 | ||
2121 | C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> encountered | |
2122 | a closing bracket where none was expected. | |
2123 | ||
2124 | =item C<Unmatched opening bracket(s): "%s"> | |
2125 | ||
2126 | C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> ran | |
2127 | out of characters in the text before closing one or more levels of nested | |
2128 | brackets. | |
2129 | ||
2130 | =item C<Unmatched embedded quote (%s)> | |
2131 | ||
2132 | C<extract_bracketed> attempted to match an embedded quoted substring, but | |
2133 | failed to find a closing quote to match it. | |
2134 | ||
2135 | =item C<Did not find closing delimiter to match '%s'> | |
2136 | ||
2137 | C<extract_quotelike> was unable to find a closing delimiter to match the | |
2138 | one that opened the quote-like operation. | |
2139 | ||
2140 | =item C<Mismatched closing bracket: expected "%c" but found "%s"> | |
2141 | ||
2142 | C<extract_bracketed>, C<extract_quotelike> or C<extract_codeblock> found | |
2143 | a valid bracket delimiter, but it was the wrong species. This usually | |
2144 | indicates a nesting error, but may indicate incorrect quoting or escaping. | |
2145 | ||
2146 | =item C<No block delimiter found after quotelike "%s"> | |
2147 | ||
2148 | C<extract_quotelike> or C<extract_codeblock> found one of the | |
2149 | quotelike operators C<q>, C<qq>, C<qw>, C<qx>, C<s>, C<tr> or C<y> | |
2150 | without a suitable block after it. | |
2151 | ||
2152 | =item C<Did not find leading dereferencer> | |
2153 | ||
2154 | C<extract_variable> was expecting one of '$', '@', or '%' at the start of | |
2155 | a variable, but didn't find any of them. | |
2156 | ||
2157 | =item C<Bad identifier after dereferencer> | |
2158 | ||
2159 | C<extract_variable> found a '$', '@', or '%' indicating a variable, but that | |
2160 | character was not followed by a legal Perl identifier. | |
2161 | ||
2162 | =item C<Did not find expected opening bracket at %s> | |
2163 | ||
2164 | C<extract_codeblock> failed to find any of the outermost opening brackets | |
2165 | that were specified. | |
2166 | ||
2167 | =item C<Improperly nested codeblock at %s> | |
2168 | ||
2169 | A nested code block was found that started with a delimiter that was specified | |
2170 | as being only to be used as an outermost bracket. | |
2171 | ||
2172 | =item C<Missing second block for quotelike "%s"> | |
2173 | ||
2174 | C<extract_codeblock> or C<extract_quotelike> found one of the | |
2175 | quotelike operators C<s>, C<tr> or C<y> followed by only one block. | |
2176 | ||
2177 | =item C<No match found for opening bracket> | |
2178 | ||
2179 | C<extract_codeblock> failed to find a closing bracket to match the outermost | |
2180 | opening bracket. | |
2181 | ||
2182 | =item C<Did not find opening tag: /%s/> | |
2183 | ||
2184 | C<extract_tagged> did not find a suitable opening tag (after any specified | |
2185 | prefix was removed). | |
2186 | ||
2187 | =item C<Unable to construct closing tag to match: /%s/> | |
2188 | ||
2189 | C<extract_tagged> matched the specified opening tag and tried to | |
2190 | modify the matched text to produce a matching closing tag (because | |
2191 | none was specified). It failed to generate the closing tag, almost | |
2192 | certainly because the opening tag did not start with a | |
2193 | bracket of some kind. | |
2194 | ||
2195 | =item C<Found invalid nested tag: %s> | |
2196 | ||
2197 | C<extract_tagged> found a nested tag that appeared in the "reject" list | |
2198 | (and the failure mode was not "MAX" or "PARA"). | |
2199 | ||
2200 | =item C<Found unbalanced nested tag: %s> | |
2201 | ||
2202 | C<extract_tagged> found a nested opening tag that was not matched by a | |
2203 | corresponding nested closing tag (and the failure mode was not "MAX" or "PARA"). | |
2204 | ||
2205 | =item C<Did not find closing tag> | |
2206 | ||
2207 | C<extract_tagged> reached the end of the text without finding a closing tag | |
2208 | to match the original opening tag (and the failure mode was not | |
2209 | "MAX" or "PARA"). | |
2210 | ||
2211 | ||
2212 | ||
2213 | ||
2214 | =back | |
2215 | ||
2216 | ||
2217 | =head1 AUTHOR | |
2218 | ||
2219 | Damian Conway (damian@conway.org) | |
2220 | ||
2221 | ||
2222 | =head1 BUGS AND IRRITATIONS | |
2223 | ||
2224 | There are undoubtedly serious bugs lurking somewhere in this code, if | |
2225 | only because parts of it give the impression of understanding a great deal | |
2226 | more about Perl than they really do. | |
2227 | ||
2228 | Bug reports and other feedback are most welcome. | |
2229 | ||
2230 | ||
2231 | =head1 COPYRIGHT | |
2232 | ||
2233 | Copyright (c) 1997-2001, Damian Conway. All Rights Reserved. | |
2234 | This module is free software. It may be used, redistributed | |
2235 | and/or modified under the same terms as Perl itself. |