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1 | # XML::Parser |
2 | # | |
3 | # Copyright (c) 1998-2000 Larry Wall and Clark Cooper | |
4 | # All rights reserved. | |
5 | # | |
6 | # This program is free software; you can redistribute it and/or | |
7 | # modify it under the same terms as Perl itself. | |
8 | ||
9 | package XML::Parser; | |
10 | ||
11 | use Carp; | |
12 | ||
13 | BEGIN { | |
14 | require XML::Parser::Expat; | |
15 | $VERSION = '2.34'; | |
16 | die "Parser.pm and Expat.pm versions don't match" | |
17 | unless $VERSION eq $XML::Parser::Expat::VERSION; | |
18 | } | |
19 | ||
20 | use strict; | |
21 | ||
22 | use vars qw($VERSION $LWP_load_failed); | |
23 | ||
24 | $LWP_load_failed = 0; | |
25 | ||
26 | sub new { | |
27 | my ($class, %args) = @_; | |
28 | my $style = $args{Style}; | |
29 | ||
30 | my $nonexopt = $args{Non_Expat_Options} ||= {}; | |
31 | ||
32 | $nonexopt->{Style} = 1; | |
33 | $nonexopt->{Non_Expat_Options} = 1; | |
34 | $nonexopt->{Handlers} = 1; | |
35 | $nonexopt->{_HNDL_TYPES} = 1; | |
36 | $nonexopt->{NoLWP} = 1; | |
37 | ||
38 | $args{_HNDL_TYPES} = {%XML::Parser::Expat::Handler_Setters}; | |
39 | $args{_HNDL_TYPES}->{Init} = 1; | |
40 | $args{_HNDL_TYPES}->{Final} = 1; | |
41 | ||
42 | $args{Handlers} ||= {}; | |
43 | my $handlers = $args{Handlers}; | |
44 | ||
45 | if (defined($style)) { | |
46 | my $stylepkg = $style; | |
47 | ||
48 | if ($stylepkg !~ /::/) { | |
49 | $stylepkg = "\u$style"; | |
50 | ||
51 | eval { | |
52 | my $fullpkg = 'XML::Parser::Style::' . $stylepkg; | |
53 | my $stylefile = $fullpkg; | |
54 | $stylefile =~ s/::/\//g; | |
55 | require "$stylefile.pm"; | |
56 | $stylepkg = $fullpkg; | |
57 | }; | |
58 | if ($@) { | |
59 | # fallback to old behaviour | |
60 | $stylepkg = 'XML::Parser::' . $stylepkg; | |
61 | } | |
62 | } | |
63 | ||
64 | my $htype; | |
65 | foreach $htype (keys %{$args{_HNDL_TYPES}}) { | |
66 | # Handlers explicity given override | |
67 | # handlers from the Style package | |
68 | unless (defined($handlers->{$htype})) { | |
69 | ||
70 | # A handler in the style package must either have | |
71 | # exactly the right case as the type name or a | |
72 | # completely lower case version of it. | |
73 | ||
74 | my $hname = "${stylepkg}::$htype"; | |
75 | if (defined(&$hname)) { | |
76 | $handlers->{$htype} = \&$hname; | |
77 | next; | |
78 | } | |
79 | ||
80 | $hname = "${stylepkg}::\L$htype"; | |
81 | if (defined(&$hname)) { | |
82 | $handlers->{$htype} = \&$hname; | |
83 | next; | |
84 | } | |
85 | } | |
86 | } | |
87 | } | |
88 | ||
89 | unless (defined($handlers->{ExternEnt}) | |
90 | or defined ($handlers->{ExternEntFin})) { | |
91 | ||
92 | if ($args{NoLWP} or $LWP_load_failed) { | |
93 | $handlers->{ExternEnt} = \&file_ext_ent_handler; | |
94 | $handlers->{ExternEntFin} = \&file_ext_ent_cleanup; | |
95 | } | |
96 | else { | |
97 | # The following just bootstraps the real LWP external entity | |
98 | # handler | |
99 | ||
100 | $handlers->{ExternEnt} = \&initial_ext_ent_handler; | |
101 | ||
102 | # No cleanup function available until LWPExternEnt.pl loaded | |
103 | } | |
104 | } | |
105 | ||
106 | $args{Pkg} ||= caller; | |
107 | bless \%args, $class; | |
108 | } # End of new | |
109 | ||
110 | sub setHandlers { | |
111 | my ($self, @handler_pairs) = @_; | |
112 | ||
113 | croak("Uneven number of arguments to setHandlers method") | |
114 | if (int(@handler_pairs) & 1); | |
115 | ||
116 | my @ret; | |
117 | while (@handler_pairs) { | |
118 | my $type = shift @handler_pairs; | |
119 | my $handler = shift @handler_pairs; | |
120 | unless (defined($self->{_HNDL_TYPES}->{$type})) { | |
121 | my @types = sort keys %{$self->{_HNDL_TYPES}}; | |
122 | ||
123 | croak("Unknown Parser handler type: $type\n Valid types: @types"); | |
124 | } | |
125 | push(@ret, $type, $self->{Handlers}->{$type}); | |
126 | $self->{Handlers}->{$type} = $handler; | |
127 | } | |
128 | ||
129 | return @ret; | |
130 | } | |
131 | ||
132 | sub parse_start { | |
133 | my $self = shift; | |
134 | my @expat_options = (); | |
135 | ||
136 | my ($key, $val); | |
137 | while (($key, $val) = each %{$self}) { | |
138 | push (@expat_options, $key, $val) | |
139 | unless exists $self->{Non_Expat_Options}->{$key}; | |
140 | } | |
141 | ||
142 | my %handlers = %{$self->{Handlers}}; | |
143 | my $init = delete $handlers{Init}; | |
144 | my $final = delete $handlers{Final}; | |
145 | ||
146 | my $expatnb = new XML::Parser::ExpatNB(@expat_options, @_); | |
147 | $expatnb->setHandlers(%handlers); | |
148 | ||
149 | &$init($expatnb) | |
150 | if defined($init); | |
151 | ||
152 | $expatnb->{_State_} = 1; | |
153 | ||
154 | $expatnb->{FinalHandler} = $final | |
155 | if defined($final); | |
156 | ||
157 | return $expatnb; | |
158 | } | |
159 | ||
160 | sub parse { | |
161 | my $self = shift; | |
162 | my $arg = shift; | |
163 | my @expat_options = (); | |
164 | my ($key, $val); | |
165 | while (($key, $val) = each %{$self}) { | |
166 | push(@expat_options, $key, $val) | |
167 | unless exists $self->{Non_Expat_Options}->{$key}; | |
168 | } | |
169 | ||
170 | my $expat = new XML::Parser::Expat(@expat_options, @_); | |
171 | my %handlers = %{$self->{Handlers}}; | |
172 | my $init = delete $handlers{Init}; | |
173 | my $final = delete $handlers{Final}; | |
174 | ||
175 | $expat->setHandlers(%handlers); | |
176 | ||
177 | if ($self->{Base}) { | |
178 | $expat->base($self->{Base}); | |
179 | } | |
180 | ||
181 | &$init($expat) | |
182 | if defined($init); | |
183 | ||
184 | my @result = (); | |
185 | my $result; | |
186 | eval { | |
187 | $result = $expat->parse($arg); | |
188 | }; | |
189 | my $err = $@; | |
190 | if ($err) { | |
191 | $expat->release; | |
192 | die $err; | |
193 | } | |
194 | ||
195 | if ($result and defined($final)) { | |
196 | if (wantarray) { | |
197 | @result = &$final($expat); | |
198 | } | |
199 | else { | |
200 | $result = &$final($expat); | |
201 | } | |
202 | } | |
203 | ||
204 | $expat->release; | |
205 | ||
206 | return unless defined wantarray; | |
207 | return wantarray ? @result : $result; | |
208 | } | |
209 | ||
210 | sub parsestring { | |
211 | my $self = shift; | |
212 | $self->parse(@_); | |
213 | } | |
214 | ||
215 | sub parsefile { | |
216 | my $self = shift; | |
217 | my $file = shift; | |
218 | local(*FILE); | |
219 | open(FILE, $file) or croak "Couldn't open $file:\n$!"; | |
220 | binmode(FILE); | |
221 | my @ret; | |
222 | my $ret; | |
223 | ||
224 | $self->{Base} = $file; | |
225 | ||
226 | if (wantarray) { | |
227 | eval { | |
228 | @ret = $self->parse(*FILE, @_); | |
229 | }; | |
230 | } | |
231 | else { | |
232 | eval { | |
233 | $ret = $self->parse(*FILE, @_); | |
234 | }; | |
235 | } | |
236 | my $err = $@; | |
237 | close(FILE); | |
238 | die $err if $err; | |
239 | ||
240 | return unless defined wantarray; | |
241 | return wantarray ? @ret : $ret; | |
242 | } | |
243 | ||
244 | sub initial_ext_ent_handler { | |
245 | # This just bootstraps in the real lwp_ext_ent_handler which | |
246 | # also loads the URI and LWP modules. | |
247 | ||
248 | unless ($LWP_load_failed) { | |
249 | local($^W) = 0; | |
250 | ||
251 | my $stat = | |
252 | eval { | |
253 | require('XML/Parser/LWPExternEnt.pl'); | |
254 | }; | |
255 | ||
256 | if ($stat) { | |
257 | $_[0]->setHandlers(ExternEnt => \&lwp_ext_ent_handler, | |
258 | ExternEntFin => \&lwp_ext_ent_cleanup); | |
259 | ||
260 | goto &lwp_ext_ent_handler; | |
261 | } | |
262 | ||
263 | # Failed to load lwp handler, act as if NoLWP | |
264 | ||
265 | $LWP_load_failed = 1; | |
266 | ||
267 | my $cmsg = "Couldn't load LWP based external entity handler\n"; | |
268 | $cmsg .= "Switching to file-based external entity handler\n"; | |
269 | $cmsg .= " (To avoid this message, use NoLWP option to XML::Parser)\n"; | |
270 | warn($cmsg); | |
271 | } | |
272 | ||
273 | $_[0]->setHandlers(ExternEnt => \&file_ext_ent_handler, | |
274 | ExternEntFin => \&file_ext_ent_cleanup); | |
275 | goto &file_ext_ent_handler; | |
276 | ||
277 | } | |
278 | ||
279 | sub file_ext_ent_handler { | |
280 | my ($xp, $base, $path) = @_; | |
281 | ||
282 | # Prepend base only for relative paths | |
283 | ||
284 | if (defined($base) | |
285 | and not ($path =~ m!^(?:[\\/]|\w+:)!)) | |
286 | { | |
287 | my $newpath = $base; | |
288 | $newpath =~ s![^\\/:]*$!$path!; | |
289 | $path = $newpath; | |
290 | } | |
291 | ||
292 | if ($path =~ /^\s*[|>+]/ | |
293 | or $path =~ /\|\s*$/) { | |
294 | $xp->{ErrorMessage} | |
295 | .= "System ID ($path) contains Perl IO control characters"; | |
296 | return undef; | |
297 | } | |
298 | ||
299 | require IO::File; | |
300 | my $fh = new IO::File($path); | |
301 | unless (defined $fh) { | |
302 | $xp->{ErrorMessage} | |
303 | .= "Failed to open $path:\n$!"; | |
304 | return undef; | |
305 | } | |
306 | ||
307 | $xp->{_BaseStack} ||= []; | |
308 | $xp->{_FhStack} ||= []; | |
309 | ||
310 | push(@{$xp->{_BaseStack}}, $base); | |
311 | push(@{$xp->{_FhStack}}, $fh); | |
312 | ||
313 | $xp->base($path); | |
314 | ||
315 | return $fh; | |
316 | } | |
317 | ||
318 | sub file_ext_ent_cleanup { | |
319 | my ($xp) = @_; | |
320 | ||
321 | my $fh = pop(@{$xp->{_FhStack}}); | |
322 | $fh->close; | |
323 | ||
324 | my $base = pop(@{$xp->{_BaseStack}}); | |
325 | $xp->base($base); | |
326 | } | |
327 | ||
328 | 1; | |
329 | ||
330 | __END__ | |
331 | ||
332 | =head1 NAME | |
333 | ||
334 | XML::Parser - A perl module for parsing XML documents | |
335 | ||
336 | =head1 SYNOPSIS | |
337 | ||
338 | use XML::Parser; | |
339 | ||
340 | $p1 = new XML::Parser(Style => 'Debug'); | |
341 | $p1->parsefile('REC-xml-19980210.xml'); | |
342 | $p1->parse('<foo id="me">Hello World</foo>'); | |
343 | ||
344 | # Alternative | |
345 | $p2 = new XML::Parser(Handlers => {Start => \&handle_start, | |
346 | End => \&handle_end, | |
347 | Char => \&handle_char}); | |
348 | $p2->parse($socket); | |
349 | ||
350 | # Another alternative | |
351 | $p3 = new XML::Parser(ErrorContext => 2); | |
352 | ||
353 | $p3->setHandlers(Char => \&text, | |
354 | Default => \&other); | |
355 | ||
356 | open(FOO, 'xmlgenerator |'); | |
357 | $p3->parse(*FOO, ProtocolEncoding => 'ISO-8859-1'); | |
358 | close(FOO); | |
359 | ||
360 | $p3->parsefile('junk.xml', ErrorContext => 3); | |
361 | ||
362 | =begin man | |
363 | .ds PI PI | |
364 | ||
365 | =end man | |
366 | ||
367 | =head1 DESCRIPTION | |
368 | ||
369 | This module provides ways to parse XML documents. It is built on top of | |
370 | L<XML::Parser::Expat>, which is a lower level interface to James Clark's | |
371 | expat library. Each call to one of the parsing methods creates a new | |
372 | instance of XML::Parser::Expat which is then used to parse the document. | |
373 | Expat options may be provided when the XML::Parser object is created. | |
374 | These options are then passed on to the Expat object on each parse call. | |
375 | They can also be given as extra arguments to the parse methods, in which | |
376 | case they override options given at XML::Parser creation time. | |
377 | ||
378 | The behavior of the parser is controlled either by C<L</Style>> and/or | |
379 | C<L</Handlers>> options, or by L</setHandlers> method. These all provide | |
380 | mechanisms for XML::Parser to set the handlers needed by XML::Parser::Expat. | |
381 | If neither C<Style> nor C<Handlers> are specified, then parsing just | |
382 | checks the document for being well-formed. | |
383 | ||
384 | When underlying handlers get called, they receive as their first parameter | |
385 | the I<Expat> object, not the Parser object. | |
386 | ||
387 | =head1 METHODS | |
388 | ||
389 | =over 4 | |
390 | ||
391 | =item new | |
392 | ||
393 | This is a class method, the constructor for XML::Parser. Options are passed | |
394 | as keyword value pairs. Recognized options are: | |
395 | ||
396 | =over 4 | |
397 | ||
398 | =item * Style | |
399 | ||
400 | This option provides an easy way to create a given style of parser. The | |
401 | built in styles are: L<"Debug">, L<"Subs">, L<"Tree">, L<"Objects">, | |
402 | and L<"Stream">. These are all defined in separate packages under | |
403 | C<XML::Parser::Style::*>, and you can find further documentation for | |
404 | each style both below, and in those packages. | |
405 | ||
406 | Custom styles can be provided by giving a full package name containing | |
407 | at least one '::'. This package should then have subs defined for each | |
408 | handler it wishes to have installed. See L<"STYLES"> below | |
409 | for a discussion of each built in style. | |
410 | ||
411 | =item * Handlers | |
412 | ||
413 | When provided, this option should be an anonymous hash containing as | |
414 | keys the type of handler and as values a sub reference to handle that | |
415 | type of event. All the handlers get passed as their 1st parameter the | |
416 | instance of expat that is parsing the document. Further details on | |
417 | handlers can be found in L<"HANDLERS">. Any handler set here | |
418 | overrides the corresponding handler set with the Style option. | |
419 | ||
420 | =item * Pkg | |
421 | ||
422 | Some styles will refer to subs defined in this package. If not provided, | |
423 | it defaults to the package which called the constructor. | |
424 | ||
425 | =item * ErrorContext | |
426 | ||
427 | This is an Expat option. When this option is defined, errors are reported | |
428 | in context. The value should be the number of lines to show on either side | |
429 | of the line in which the error occurred. | |
430 | ||
431 | =item * ProtocolEncoding | |
432 | ||
433 | This is an Expat option. This sets the protocol encoding name. It defaults | |
434 | to none. The built-in encodings are: C<UTF-8>, C<ISO-8859-1>, C<UTF-16>, and | |
435 | C<US-ASCII>. Other encodings may be used if they have encoding maps in one | |
436 | of the directories in the @Encoding_Path list. Check L<"ENCODINGS"> for | |
437 | more information on encoding maps. Setting the protocol encoding overrides | |
438 | any encoding in the XML declaration. | |
439 | ||
440 | =item * Namespaces | |
441 | ||
442 | This is an Expat option. If this is set to a true value, then namespace | |
443 | processing is done during the parse. See L<XML::Parser::Expat/"Namespaces"> | |
444 | for further discussion of namespace processing. | |
445 | ||
446 | =item * NoExpand | |
447 | ||
448 | This is an Expat option. Normally, the parser will try to expand references | |
449 | to entities defined in the internal subset. If this option is set to a true | |
450 | value, and a default handler is also set, then the default handler will be | |
451 | called when an entity reference is seen in text. This has no effect if a | |
452 | default handler has not been registered, and it has no effect on the expansion | |
453 | of entity references inside attribute values. | |
454 | ||
455 | =item * Stream_Delimiter | |
456 | ||
457 | This is an Expat option. It takes a string value. When this string is found | |
458 | alone on a line while parsing from a stream, then the parse is ended as if it | |
459 | saw an end of file. The intended use is with a stream of xml documents in a | |
460 | MIME multipart format. The string should not contain a trailing newline. | |
461 | ||
462 | =item * ParseParamEnt | |
463 | ||
464 | This is an Expat option. Unless standalone is set to "yes" in the XML | |
465 | declaration, setting this to a true value allows the external DTD to be read, | |
466 | and parameter entities to be parsed and expanded. | |
467 | ||
468 | =item * NoLWP | |
469 | ||
470 | This option has no effect if the ExternEnt or ExternEntFin handlers are | |
471 | directly set. Otherwise, if true, it forces the use of a file based external | |
472 | entity handler. | |
473 | ||
474 | =item * Non-Expat-Options | |
475 | ||
476 | If provided, this should be an anonymous hash whose keys are options that | |
477 | shouldn't be passed to Expat. This should only be of concern to those | |
478 | subclassing XML::Parser. | |
479 | ||
480 | =back | |
481 | ||
482 | =item setHandlers(TYPE, HANDLER [, TYPE, HANDLER [...]]) | |
483 | ||
484 | This method registers handlers for various parser events. It overrides any | |
485 | previous handlers registered through the Style or Handler options or through | |
486 | earlier calls to setHandlers. By providing a false or undefined value as | |
487 | the handler, the existing handler can be unset. | |
488 | ||
489 | This method returns a list of type, handler pairs corresponding to the | |
490 | input. The handlers returned are the ones that were in effect prior to | |
491 | the call. | |
492 | ||
493 | See a description of the handler types in L<"HANDLERS">. | |
494 | ||
495 | =item parse(SOURCE [, OPT => OPT_VALUE [...]]) | |
496 | ||
497 | The SOURCE parameter should either be a string containing the whole XML | |
498 | document, or it should be an open IO::Handle. Constructor options to | |
499 | XML::Parser::Expat given as keyword-value pairs may follow the SOURCE | |
500 | parameter. These override, for this call, any options or attributes passed | |
501 | through from the XML::Parser instance. | |
502 | ||
503 | A die call is thrown if a parse error occurs. Otherwise it will return 1 | |
504 | or whatever is returned from the B<Final> handler, if one is installed. | |
505 | In other words, what parse may return depends on the style. | |
506 | ||
507 | =item parsestring | |
508 | ||
509 | This is just an alias for parse for backwards compatibility. | |
510 | ||
511 | =item parsefile(FILE [, OPT => OPT_VALUE [...]]) | |
512 | ||
513 | Open FILE for reading, then call parse with the open handle. The file | |
514 | is closed no matter how parse returns. Returns what parse returns. | |
515 | ||
516 | =item parse_start([ OPT => OPT_VALUE [...]]) | |
517 | ||
518 | Create and return a new instance of XML::Parser::ExpatNB. Constructor | |
519 | options may be provided. If an init handler has been provided, it is | |
520 | called before returning the ExpatNB object. Documents are parsed by | |
521 | making incremental calls to the parse_more method of this object, which | |
522 | takes a string. A single call to the parse_done method of this object, | |
523 | which takes no arguments, indicates that the document is finished. | |
524 | ||
525 | If there is a final handler installed, it is executed by the parse_done | |
526 | method before returning and the parse_done method returns whatever is | |
527 | returned by the final handler. | |
528 | ||
529 | =back | |
530 | ||
531 | =head1 HANDLERS | |
532 | ||
533 | Expat is an event based parser. As the parser recognizes parts of the | |
534 | document (say the start or end tag for an XML element), then any handlers | |
535 | registered for that type of an event are called with suitable parameters. | |
536 | All handlers receive an instance of XML::Parser::Expat as their first | |
537 | argument. See L<XML::Parser::Expat/"METHODS"> for a discussion of the | |
538 | methods that can be called on this object. | |
539 | ||
540 | =head2 Init (Expat) | |
541 | ||
542 | This is called just before the parsing of the document starts. | |
543 | ||
544 | =head2 Final (Expat) | |
545 | ||
546 | This is called just after parsing has finished, but only if no errors | |
547 | occurred during the parse. Parse returns what this returns. | |
548 | ||
549 | =head2 Start (Expat, Element [, Attr, Val [,...]]) | |
550 | ||
551 | This event is generated when an XML start tag is recognized. Element is the | |
552 | name of the XML element type that is opened with the start tag. The Attr & | |
553 | Val pairs are generated for each attribute in the start tag. | |
554 | ||
555 | =head2 End (Expat, Element) | |
556 | ||
557 | This event is generated when an XML end tag is recognized. Note that | |
558 | an XML empty tag (<foo/>) generates both a start and an end event. | |
559 | ||
560 | =head2 Char (Expat, String) | |
561 | ||
562 | This event is generated when non-markup is recognized. The non-markup | |
563 | sequence of characters is in String. A single non-markup sequence of | |
564 | characters may generate multiple calls to this handler. Whatever the | |
565 | encoding of the string in the original document, this is given to the | |
566 | handler in UTF-8. | |
567 | ||
568 | =head2 Proc (Expat, Target, Data) | |
569 | ||
570 | This event is generated when a processing instruction is recognized. | |
571 | ||
572 | =head2 Comment (Expat, Data) | |
573 | ||
574 | This event is generated when a comment is recognized. | |
575 | ||
576 | =head2 CdataStart (Expat) | |
577 | ||
578 | This is called at the start of a CDATA section. | |
579 | ||
580 | =head2 CdataEnd (Expat) | |
581 | ||
582 | This is called at the end of a CDATA section. | |
583 | ||
584 | =head2 Default (Expat, String) | |
585 | ||
586 | This is called for any characters that don't have a registered handler. | |
587 | This includes both characters that are part of markup for which no | |
588 | events are generated (markup declarations) and characters that | |
589 | could generate events, but for which no handler has been registered. | |
590 | ||
591 | Whatever the encoding in the original document, the string is returned to | |
592 | the handler in UTF-8. | |
593 | ||
594 | =head2 Unparsed (Expat, Entity, Base, Sysid, Pubid, Notation) | |
595 | ||
596 | This is called for a declaration of an unparsed entity. Entity is the name | |
597 | of the entity. Base is the base to be used for resolving a relative URI. | |
598 | Sysid is the system id. Pubid is the public id. Notation is the notation | |
599 | name. Base and Pubid may be undefined. | |
600 | ||
601 | =head2 Notation (Expat, Notation, Base, Sysid, Pubid) | |
602 | ||
603 | This is called for a declaration of notation. Notation is the notation name. | |
604 | Base is the base to be used for resolving a relative URI. Sysid is the system | |
605 | id. Pubid is the public id. Base, Sysid, and Pubid may all be undefined. | |
606 | ||
607 | =head2 ExternEnt (Expat, Base, Sysid, Pubid) | |
608 | ||
609 | This is called when an external entity is referenced. Base is the base to be | |
610 | used for resolving a relative URI. Sysid is the system id. Pubid is the public | |
611 | id. Base, and Pubid may be undefined. | |
612 | ||
613 | This handler should either return a string, which represents the contents of | |
614 | the external entity, or return an open filehandle that can be read to obtain | |
615 | the contents of the external entity, or return undef, which indicates the | |
616 | external entity couldn't be found and will generate a parse error. | |
617 | ||
618 | If an open filehandle is returned, it must be returned as either a glob | |
619 | (*FOO) or as a reference to a glob (e.g. an instance of IO::Handle). | |
620 | ||
621 | A default handler is installed for this event. The default handler is | |
622 | XML::Parser::lwp_ext_ent_handler unless the NoLWP option was provided with | |
623 | a true value, otherwise XML::Parser::file_ext_ent_handler is the default | |
624 | handler for external entities. Even without the NoLWP option, if the | |
625 | URI or LWP modules are missing, the file based handler ends up being used | |
626 | after giving a warning on the first external entity reference. | |
627 | ||
628 | The LWP external entity handler will use proxies defined in the environment | |
629 | (http_proxy, ftp_proxy, etc.). | |
630 | ||
631 | Please note that the LWP external entity handler reads the entire | |
632 | entity into a string and returns it, where as the file handler opens a | |
633 | filehandle. | |
634 | ||
635 | Also note that the file external entity handler will likely choke on | |
636 | absolute URIs or file names that don't fit the conventions of the local | |
637 | operating system. | |
638 | ||
639 | The expat base method can be used to set a basename for | |
640 | relative pathnames. If no basename is given, or if the basename is itself | |
641 | a relative name, then it is relative to the current working directory. | |
642 | ||
643 | =head2 ExternEntFin (Expat) | |
644 | ||
645 | This is called after parsing an external entity. It's not called unless | |
646 | an ExternEnt handler is also set. There is a default handler installed | |
647 | that pairs with the default ExternEnt handler. | |
648 | ||
649 | If you're going to install your own ExternEnt handler, then you should | |
650 | set (or unset) this handler too. | |
651 | ||
652 | =head2 Entity (Expat, Name, Val, Sysid, Pubid, Ndata, IsParam) | |
653 | ||
654 | This is called when an entity is declared. For internal entities, the Val | |
655 | parameter will contain the value and the remaining three parameters will be | |
656 | undefined. For external entities, the Val parameter will be undefined, the | |
657 | Sysid parameter will have the system id, the Pubid parameter will have the | |
658 | public id if it was provided (it will be undefined otherwise), the Ndata | |
659 | parameter will contain the notation for unparsed entities. If this is a | |
660 | parameter entity declaration, then the IsParam parameter is true. | |
661 | ||
662 | Note that this handler and the Unparsed handler above overlap. If both are | |
663 | set, then this handler will not be called for unparsed entities. | |
664 | ||
665 | =head2 Element (Expat, Name, Model) | |
666 | ||
667 | The element handler is called when an element declaration is found. Name | |
668 | is the element name, and Model is the content model as an XML::Parser::Content | |
669 | object. See L<XML::Parser::Expat/"XML::Parser::ContentModel Methods"> | |
670 | for methods available for this class. | |
671 | ||
672 | =head2 Attlist (Expat, Elname, Attname, Type, Default, Fixed) | |
673 | ||
674 | This handler is called for each attribute in an ATTLIST declaration. | |
675 | So an ATTLIST declaration that has multiple attributes will generate multiple | |
676 | calls to this handler. The Elname parameter is the name of the element with | |
677 | which the attribute is being associated. The Attname parameter is the name | |
678 | of the attribute. Type is the attribute type, given as a string. Default is | |
679 | the default value, which will either be "#REQUIRED", "#IMPLIED" or a quoted | |
680 | string (i.e. the returned string will begin and end with a quote character). | |
681 | If Fixed is true, then this is a fixed attribute. | |
682 | ||
683 | =head2 Doctype (Expat, Name, Sysid, Pubid, Internal) | |
684 | ||
685 | This handler is called for DOCTYPE declarations. Name is the document type | |
686 | name. Sysid is the system id of the document type, if it was provided, | |
687 | otherwise it's undefined. Pubid is the public id of the document type, | |
688 | which will be undefined if no public id was given. Internal is the internal | |
689 | subset, given as a string. If there was no internal subset, it will be | |
690 | undefined. Internal will contain all whitespace, comments, processing | |
691 | instructions, and declarations seen in the internal subset. The declarations | |
692 | will be there whether or not they have been processed by another handler | |
693 | (except for unparsed entities processed by the Unparsed handler). However, | |
694 | comments and processing instructions will not appear if they've been processed | |
695 | by their respective handlers. | |
696 | ||
697 | =head2 * DoctypeFin (Parser) | |
698 | ||
699 | This handler is called after parsing of the DOCTYPE declaration has finished, | |
700 | including any internal or external DTD declarations. | |
701 | ||
702 | =head2 XMLDecl (Expat, Version, Encoding, Standalone) | |
703 | ||
704 | This handler is called for xml declarations. Version is a string containg | |
705 | the version. Encoding is either undefined or contains an encoding string. | |
706 | Standalone will be either true, false, or undefined if the standalone attribute | |
707 | is yes, no, or not made respectively. | |
708 | ||
709 | =head1 STYLES | |
710 | ||
711 | =head2 Debug | |
712 | ||
713 | This just prints out the document in outline form. Nothing special is | |
714 | returned by parse. | |
715 | ||
716 | =head2 Subs | |
717 | ||
718 | Each time an element starts, a sub by that name in the package specified | |
719 | by the Pkg option is called with the same parameters that the Start | |
720 | handler gets called with. | |
721 | ||
722 | Each time an element ends, a sub with that name appended with an underscore | |
723 | ("_"), is called with the same parameters that the End handler gets called | |
724 | with. | |
725 | ||
726 | Nothing special is returned by parse. | |
727 | ||
728 | =head2 Tree | |
729 | ||
730 | Parse will return a parse tree for the document. Each node in the tree | |
731 | takes the form of a tag, content pair. Text nodes are represented with | |
732 | a pseudo-tag of "0" and the string that is their content. For elements, | |
733 | the content is an array reference. The first item in the array is a | |
734 | (possibly empty) hash reference containing attributes. The remainder of | |
735 | the array is a sequence of tag-content pairs representing the content | |
736 | of the element. | |
737 | ||
738 | So for example the result of parsing: | |
739 | ||
740 | <foo><head id="a">Hello <em>there</em></head><bar>Howdy<ref/></bar>do</foo> | |
741 | ||
742 | would be: | |
743 | ||
744 | Tag Content | |
745 | ================================================================== | |
746 | [foo, [{}, head, [{id => "a"}, 0, "Hello ", em, [{}, 0, "there"]], | |
747 | bar, [ {}, 0, "Howdy", ref, [{}]], | |
748 | 0, "do" | |
749 | ] | |
750 | ] | |
751 | ||
752 | The root document "foo", has 3 children: a "head" element, a "bar" | |
753 | element and the text "do". After the empty attribute hash, these are | |
754 | represented in it's contents by 3 tag-content pairs. | |
755 | ||
756 | =head2 Objects | |
757 | ||
758 | This is similar to the Tree style, except that a hash object is created for | |
759 | each element. The corresponding object will be in the class whose name | |
760 | is created by appending "::" and the element name to the package set with | |
761 | the Pkg option. Non-markup text will be in the ::Characters class. The | |
762 | contents of the corresponding object will be in an anonymous array that | |
763 | is the value of the Kids property for that object. | |
764 | ||
765 | =head2 Stream | |
766 | ||
767 | This style also uses the Pkg package. If none of the subs that this | |
768 | style looks for is there, then the effect of parsing with this style is | |
769 | to print a canonical copy of the document without comments or declarations. | |
770 | All the subs receive as their 1st parameter the Expat instance for the | |
771 | document they're parsing. | |
772 | ||
773 | It looks for the following routines: | |
774 | ||
775 | =over 4 | |
776 | ||
777 | =item * StartDocument | |
778 | ||
779 | Called at the start of the parse . | |
780 | ||
781 | =item * StartTag | |
782 | ||
783 | Called for every start tag with a second parameter of the element type. The $_ | |
784 | variable will contain a copy of the tag and the %_ variable will contain | |
785 | attribute values supplied for that element. | |
786 | ||
787 | =item * EndTag | |
788 | ||
789 | Called for every end tag with a second parameter of the element type. The $_ | |
790 | variable will contain a copy of the end tag. | |
791 | ||
792 | =item * Text | |
793 | ||
794 | Called just before start or end tags with accumulated non-markup text in | |
795 | the $_ variable. | |
796 | ||
797 | =item * PI | |
798 | ||
799 | Called for processing instructions. The $_ variable will contain a copy of | |
800 | the PI and the target and data are sent as 2nd and 3rd parameters | |
801 | respectively. | |
802 | ||
803 | =item * EndDocument | |
804 | ||
805 | Called at conclusion of the parse. | |
806 | ||
807 | =back | |
808 | ||
809 | =head1 ENCODINGS | |
810 | ||
811 | XML documents may be encoded in character sets other than Unicode as | |
812 | long as they may be mapped into the Unicode character set. Expat has | |
813 | further restrictions on encodings. Read the xmlparse.h header file in | |
814 | the expat distribution to see details on these restrictions. | |
815 | ||
816 | Expat has built-in encodings for: C<UTF-8>, C<ISO-8859-1>, C<UTF-16>, and | |
817 | C<US-ASCII>. Encodings are set either through the XML declaration | |
818 | encoding attribute or through the ProtocolEncoding option to XML::Parser | |
819 | or XML::Parser::Expat. | |
820 | ||
821 | For encodings other than the built-ins, expat calls the function | |
822 | load_encoding in the Expat package with the encoding name. This function | |
823 | looks for a file in the path list @XML::Parser::Expat::Encoding_Path, that | |
824 | matches the lower-cased name with a '.enc' extension. The first one it | |
825 | finds, it loads. | |
826 | ||
827 | If you wish to build your own encoding maps, check out the XML::Encoding | |
828 | module from CPAN. | |
829 | ||
830 | =head1 AUTHORS | |
831 | ||
832 | Larry Wall <F<larry@wall.org>> wrote version 1.0. | |
833 | ||
834 | Clark Cooper <F<coopercc@netheaven.com>> picked up support, changed the API | |
835 | for this version (2.x), provided documentation, | |
836 | and added some standard package features. | |
837 | ||
838 | Matt Sergeant <F<matt@sergeant.org>> is now maintaining XML::Parser | |
839 | ||
840 | =cut |