3 # Copyright 1996-2009, Gisle Aas.
4 # Copyright 1999-2000, Michael A. Chase.
6 # This library is free software; you can redistribute it and/or
7 # modify it under the same terms as Perl itself.
10 use vars qw($VERSION @ISA);
14 require HTML::Entities;
17 XSLoader::load('HTML::Parser', $VERSION);
22 my $self = bless {}, $class;
23 return $self->init(@_);
33 my $api_version = delete $arg{api_version} || (@_ ? 3 : 2);
34 if ($api_version >= 4) {
36 Carp::croak("API version $api_version not supported " .
37 "by HTML::Parser $VERSION");
40 if ($api_version < 3) {
41 # Set up method callbacks compatible with HTML-Parser-2.xx
42 $self->handler(text => "text", "self,text,is_cdata");
43 $self->handler(end => "end", "self,tagname,text");
44 $self->handler(process => "process", "self,token0,text");
45 $self->handler(start => "start",
46 "self,tagname,attr,attrseq,text");
48 $self->handler(comment =>
50 my($self, $tokens) = @_;
56 $self->handler(declaration =>
59 $self->declaration(substr($_[0], 2, -1));
63 if (my $h = delete $arg{handlers}) {
64 $h = {@$h} if ref($h) eq "ARRAY";
65 while (my($event, $cb) = each %$h) {
66 $self->handler($event => @$cb);
70 # In the end we try to assume plain attribute or handler
71 while (my($option, $val) = each %arg) {
72 if ($option =~ /^(\w+)_h$/) {
73 $self->handler($1 => @$val);
75 elsif ($option =~ /^(text|start|end|process|declaration|comment)$/) {
77 Carp::croak("Bad constructor option '$option'");
90 my($self, $file) = @_;
92 if (!ref($file) && ref(\$file) ne "GLOB") {
93 # Assume $file is a filename
95 open(F, "<", $file) || return undef;
96 binmode(F); # should we? good for byte counts
101 while (read($file, $chunk, 512)) {
102 $self->parse($chunk) || last;
104 close($file) if $opened;
109 sub netscape_buggy_comment # legacy
113 Carp::carp("netscape_buggy_comment() is deprecated. " .
114 "Please use the strict_comment() method instead");
115 my $old = !$self->strict_comment;
116 $self->strict_comment(!shift) if @_;
120 # set up method stubs
125 *declaration = \&text;
135 HTML::Parser - HTML parser class
141 # Create parser object
142 $p = HTML::Parser->new( api_version => 3,
143 start_h => [\&start, "tagname, attr"],
144 end_h => [\&end, "tagname"],
145 marked_sections => 1,
148 # Parse document text chunk by chunk
152 $p->eof; # signal end of document
154 # Parse directly from file
155 $p->parse_file("foo.html");
157 open(my $fh, "<:utf8", "foo.html") || die;
162 Objects of the C<HTML::Parser> class will recognize markup and
163 separate it from plain text (alias data content) in HTML
164 documents. As different kinds of markup and text are recognized, the
165 corresponding event handlers are invoked.
167 C<HTML::Parser> is not a generic SGML parser. We have tried to
168 make it able to deal with the HTML that is actually "out there", and
169 it normally parses as closely as possible to the way the popular web
170 browsers do it instead of strictly following one of the many HTML
171 specifications from W3C. Where there is disagreement, there is often
172 an option that you can enable to get the official behaviour.
174 The document to be parsed may be supplied in arbitrary chunks. This
175 makes on-the-fly parsing as documents are received from the network
178 If event driven parsing does not feel right for your application, you
179 might want to use C<HTML::PullParser>. This is an C<HTML::Parser>
180 subclass that allows a more conventional program structure.
185 The following method is used to construct a new C<HTML::Parser> object:
189 =item $p = HTML::Parser->new( %options_and_handlers )
191 This class method creates a new C<HTML::Parser> object and
192 returns it. Key/value argument pairs may be provided to assign event
193 handlers or initialize parser options. The handlers and parser
194 options can also be set or modified later by the method calls described below.
196 If a top level key is in the form "<event>_h" (e.g., "text_h") then it
197 assigns a handler to that event, otherwise it initializes a parser
198 option. The event handler specification value must be an array
199 reference. Multiple handlers may also be assigned with the 'handlers
200 => [%handlers]' option. See examples below.
202 If new() is called without any arguments, it will create a parser that
203 uses callback methods compatible with version 2 of C<HTML::Parser>.
204 See the section on "version 2 compatibility" below for details.
206 The special constructor option 'api_version => 2' can be used to
207 initialize version 2 callbacks while still setting other options and
208 handlers. The 'api_version => 3' option can be used if you don't want
209 to set any options and don't want to fall back to v2 compatible
214 $p = HTML::Parser->new(api_version => 3,
215 text_h => [ sub {...}, "dtext" ]);
217 This creates a new parser object with a text event handler subroutine
218 that receives the original text with general entities decoded.
220 $p = HTML::Parser->new(api_version => 3,
221 start_h => [ 'my_start', "self,tokens" ]);
223 This creates a new parser object with a start event handler method
224 that receives the $p and the tokens array.
226 $p = HTML::Parser->new(api_version => 3,
227 handlers => { text => [\@array, "event,text"],
228 comment => [\@array, "event,text"],
231 This creates a new parser object that stores the event type and the
232 original text in @array for text and comment events.
236 The following methods feed the HTML document
237 to the C<HTML::Parser> object:
241 =item $p->parse( $string )
243 Parse $string as the next chunk of the HTML document. Handlers invoked should
244 not attempt to modify the $string in-place until $p->parse returns.
246 If an invoked event handler aborts parsing by calling $p->eof, then $p->parse()
247 will return a FALSE value. Otherwise the return value is a reference to the
250 =item $p->parse( $code_ref )
252 If a code reference is passed as the argument to be parsed, then the
253 chunks to be parsed are obtained by invoking this function repeatedly.
254 Parsing continues until the function returns an empty (or undefined)
255 result. When this happens $p->eof is automatically signaled.
257 Parsing will also abort if one of the event handlers calls $p->eof.
259 The effect of this is the same as:
262 my $chunk = &$code_ref();
263 if (!defined($chunk) || !length($chunk)) {
267 $p->parse($chunk) || return undef;
270 But it is more efficient as this loop runs internally in XS code.
272 =item $p->parse_file( $file )
274 Parse text directly from a file. The $file argument can be a
275 filename, an open file handle, or a reference to an open file
278 If $file contains a filename and the file can't be opened, then the
279 method returns an undefined value and $! tells why it failed.
280 Otherwise the return value is a reference to the parser object.
282 If a file handle is passed as the $file argument, then the file will
283 normally be read until EOF, but not closed.
285 If an invoked event handler aborts parsing by calling $p->eof,
286 then $p->parse_file() may not have read the entire file.
288 On systems with multi-byte line terminators, the values passed for the
289 offset and length argspecs may be too low if parse_file() is called on
290 a file handle that is not in binary mode.
292 If a filename is passed in, then parse_file() will open the file in
297 Signals the end of the HTML document. Calling the $p->eof method
298 outside a handler callback will flush any remaining buffered text
299 (which triggers the C<text> event if there is any remaining text).
301 Calling $p->eof inside a handler will terminate parsing at that point
302 and cause $p->parse to return a FALSE value. This also terminates
303 parsing by $p->parse_file().
305 After $p->eof has been called, the parse() and parse_file() methods
306 can be invoked to feed new documents with the parser object.
308 The return value from eof() is a reference to the parser object.
313 Most parser options are controlled by boolean attributes.
314 Each boolean attribute is enabled by calling the corresponding method
315 with a TRUE argument and disabled with a FALSE argument. The
316 attribute value is left unchanged if no argument is given. The return
317 value from each method is the old attribute value.
319 Methods that can be used to get and/or set parser options are:
323 =item $p->attr_encoded
325 =item $p->attr_encoded( $bool )
327 By default, the C<attr> and C<@attr> argspecs will have general
328 entities for attribute values decoded. Enabling this attribute leaves
333 =item $p->backquote( $bool )
335 By default, only ' and " are recognized as quote characters around
336 attribute values. MSIE also recognizes backquotes for some reason.
337 Enabling this attribute provides compatibility with this behaviour.
339 =item $p->boolean_attribute_value( $val )
341 This method sets the value reported for boolean attributes inside HTML
342 start tags. By default, the name of the attribute is also used as its
343 value. This affects the values reported for C<tokens> and C<attr>
346 =item $p->case_sensitive
348 =item $p->case_sensitive( $bool )
350 By default, tagnames and attribute names are down-cased. Enabling this
351 attribute leaves them as found in the HTML source document.
353 =item $p->closing_plaintext
355 =item $p->closing_plaintext( $bool )
357 By default, "plaintext" element can never be closed. Everything up to
358 the end of the document is parsed in CDATA mode. This historical
359 behaviour is what at least MSIE does. Enabling this attribute makes
360 closing "</plaintext>" tag effective and the parsing process will resume
361 after seeing this tag. This emulates early gecko-based browsers.
363 =item $p->empty_element_tags
365 =item $p->empty_element_tags( $bool )
367 By default, empty element tags are not recognized as such and the "/"
368 before ">" is just treated like a normal name character (unless
369 C<strict_names> is enabled). Enabling this attribute make
370 C<HTML::Parser> recognize these tags.
372 Empty element tags look like start tags, but end with the character
373 sequence "/>" instead of ">". When recognized by C<HTML::Parser> they
374 cause an artificial end event in addition to the start event. The
375 C<text> for the artificial end event will be empty and the C<tokenpos>
376 array will be undefined even though the the token array will have one
377 element containing the tag name.
379 =item $p->marked_sections
381 =item $p->marked_sections( $bool )
383 By default, section markings like <![CDATA[...]]> are treated like
384 ordinary text. When this attribute is enabled section markings are
387 There are currently no events associated with the marked section
388 markup, but the text can be returned as C<skipped_text>.
390 =item $p->strict_comment
392 =item $p->strict_comment( $bool )
394 By default, comments are terminated by the first occurrence of "-->".
395 This is the behaviour of most popular browsers (like Mozilla, Opera and
396 MSIE), but it is not correct according to the official HTML
397 standard. Officially, you need an even number of "--" tokens before
398 the closing ">" is recognized and there may not be anything but
399 whitespace between an even and an odd "--".
401 The official behaviour is enabled by enabling this attribute.
403 Enabling of 'strict_comment' also disables recognizing these forms as
412 =item $p->strict_end( $bool )
414 By default, attributes and other junk are allowed to be present on end tags in a
415 manner that emulates MSIE's behaviour.
417 The official behaviour is enabled with this attribute. If enabled,
418 only whitespace is allowed between the tagname and the final ">".
420 =item $p->strict_names
422 =item $p->strict_names( $bool )
424 By default, almost anything is allowed in tag and attribute names.
425 This is the behaviour of most popular browsers and allows us to parse
426 some broken tags with invalid attribute values like:
428 <IMG SRC=newprevlstGr.gif ALT=[PREV LIST] BORDER=0>
430 By default, "LIST]" is parsed as a boolean attribute, not as
431 part of the ALT value as was clearly intended. This is also what
434 The official behaviour is enabled by enabling this attribute. If
435 enabled, it will cause the tag above to be reported as text
436 since "LIST]" is not a legal attribute name.
438 =item $p->unbroken_text
440 =item $p->unbroken_text( $bool )
442 By default, blocks of text are given to the text handler as soon as
443 possible (but the parser takes care always to break text at a
444 boundary between whitespace and non-whitespace so single words and
445 entities can always be decoded safely). This might create breaks that
446 make it hard to do transformations on the text. When this attribute is
447 enabled, blocks of text are always reported in one piece. This will
448 delay the text event until the following (non-text) event has been
449 recognized by the parser.
451 Note that the C<offset> argspec will give you the offset of the first
452 segment of text and C<length> is the combined length of the segments.
453 Since there might be ignored tags in between, these numbers can't be
454 used to directly index in the original document file.
458 =item $p->utf8_mode( $bool )
460 Enable this option when parsing raw undecoded UTF-8. This tells the
461 parser that the entities expanded for strings reported by C<attr>,
462 C<@attr> and C<dtext> should be expanded as decoded UTF-8 so they end
463 up compatible with the surrounding text.
465 If C<utf8_mode> is enabled then it is an error to pass strings
466 containing characters with code above 255 to the parse() method, and
467 the parse() method will croak if you try.
469 Example: The Unicode character "\x{2665}" is "\xE2\x99\xA5" when UTF-8
470 encoded. The character can also be represented by the entity
471 "♥" or "♥". If we feed the parser:
473 $p->parse("\xE2\x99\xA5♥");
475 then C<dtext> will be reported as "\xE2\x99\xA5\x{2665}" without
476 C<utf8_mode> enabled, but as "\xE2\x99\xA5\xE2\x99\xA5" when enabled.
477 The later string is what you want.
479 This option is only available with perl-5.8 or better.
483 =item $p->xml_mode( $bool )
485 Enabling this attribute changes the parser to allow some XML
486 constructs. This enables the behaviour controlled by individually by
487 the C<case_sensitive>, C<empty_element_tags>, C<strict_names> and
488 C<xml_pic> attributes and also suppresses special treatment of
489 elements that are parsed as CDATA for HTML.
493 =item $p->xml_pic( $bool )
495 By default, I<processing instructions> are terminated by ">". When
496 this attribute is enabled, processing instructions are terminated by
501 As markup and text is recognized, handlers are invoked. The following
502 method is used to set up handlers for different events:
506 =item $p->handler( event => \&subroutine, $argspec )
508 =item $p->handler( event => $method_name, $argspec )
510 =item $p->handler( event => \@accum, $argspec )
512 =item $p->handler( event => "" );
514 =item $p->handler( event => undef );
516 =item $p->handler( event );
518 This method assigns a subroutine, method, or array to handle an event.
520 Event is one of C<text>, C<start>, C<end>, C<declaration>, C<comment>,
521 C<process>, C<start_document>, C<end_document> or C<default>.
523 The C<\&subroutine> is a reference to a subroutine which is called to handle
526 The C<$method_name> is the name of a method of $p which is called to handle
529 The C<@accum> is an array that will hold the event information as
532 If the second argument is "", the event is ignored.
533 If it is undef, the default handler is invoked for the event.
535 The C<$argspec> is a string that describes the information to be reported
536 for the event. Any requested information that does not apply to a
537 specific event is passed as C<undef>. If argspec is omitted, then it
540 The return value from $p->handler is the old callback routine or a
541 reference to the accumulator array.
543 Any return values from handler callback routines/methods are always
544 ignored. A handler callback can request parsing to be aborted by
545 invoking the $p->eof method. A handler callback is not allowed to
546 invoke the $p->parse() or $p->parse_file() method. An exception will
547 be raised if it tries.
551 $p->handler(start => "start", 'self, attr, attrseq, text' );
553 This causes the "start" method of object $p to be called for 'start' events.
554 The callback signature is $p->start(\%attr, \@attr_seq, $text).
556 $p->handler(start => \&start, 'attr, attrseq, text' );
558 This causes subroutine start() to be called for 'start' events.
559 The callback signature is start(\%attr, \@attr_seq, $text).
561 $p->handler(start => \@accum, '"S", attr, attrseq, text' );
563 This causes 'start' event information to be saved in @accum.
564 The array elements will be ['S', \%attr, \@attr_seq, $text].
566 $p->handler(start => "");
568 This causes 'start' events to be ignored. It also suppresses
569 invocations of any default handler for start events. It is in most
570 cases equivalent to $p->handler(start => sub {}), but is more
571 efficient. It is different from the empty-sub-handler in that
572 C<skipped_text> is not reset by it.
574 $p->handler(start => undef);
576 This causes no handler to be associated with start events.
577 If there is a default handler it will be invoked.
581 Filters based on tags can be set up to limit the number of events
582 reported. The main bottleneck during parsing is often the huge number
583 of callbacks made from the parser. Applying filters can improve
584 performance significantly.
586 The following methods control filters:
590 =item $p->ignore_elements( @tags )
592 Both the C<start> event and the C<end> event as well as any events that
593 would be reported in between are suppressed. The ignored elements can
594 contain nested occurrences of itself. Example:
596 $p->ignore_elements(qw(script style));
598 The C<script> and C<style> tags will always nest properly since their
599 content is parsed in CDATA mode. For most other tags
600 C<ignore_elements> must be used with caution since HTML is often not
603 =item $p->ignore_tags( @tags )
605 Any C<start> and C<end> events involving any of the tags given are
606 suppressed. To reset the filter (i.e. don't suppress any C<start> and
607 C<end> events), call C<ignore_tags> without an argument.
609 =item $p->report_tags( @tags )
611 Any C<start> and C<end> events involving any of the tags I<not> given
612 are suppressed. To reset the filter (i.e. report all C<start> and
613 C<end> events), call C<report_tags> without an argument.
617 Internally, the system has two filter lists, one for C<report_tags>
618 and one for C<ignore_tags>, and both filters are applied. This
619 effectively gives C<ignore_tags> precedence over C<report_tags>.
623 $p->ignore_tags(qw(style));
624 $p->report_tags(qw(script style));
626 results in only C<script> events being reported.
630 Argspec is a string containing a comma-separated list that describes
631 the information reported by the event. The following argspec
632 identifier names can be used:
638 Attr causes a reference to a hash of attribute name/value pairs to be
641 Boolean attributes' values are either the value set by
642 $p->boolean_attribute_value, or the attribute name if no value has been
643 set by $p->boolean_attribute_value.
645 This passes undef except for C<start> events.
647 Unless C<xml_mode> or C<case_sensitive> is enabled, the attribute
648 names are forced to lower case.
650 General entities are decoded in the attribute values and
651 one layer of matching quotes enclosing the attribute values is removed.
653 The Unicode character set is assumed for entity decoding. With Perl
654 version 5.6 or earlier only the Latin-1 range is supported, and
655 entities for characters outside the range 0..255 are left unchanged.
659 Basically the same as C<attr>, but keys and values are passed as
660 individual arguments and the original sequence of the attributes is
661 kept. The parameters passed will be the same as the @attr calculated
664 @attr = map { $_ => $attr->{$_} } @$attrseq;
666 assuming $attr and $attrseq here are the hash and array passed as the
667 result of C<attr> and C<attrseq> argspecs.
669 This passes no values for events besides C<start>.
673 Attrseq causes a reference to an array of attribute names to be
674 passed. This can be useful if you want to walk the C<attr> hash in
675 the original sequence.
677 This passes undef except for C<start> events.
679 Unless C<xml_mode> or C<case_sensitive> is enabled, the attribute
680 names are forced to lower case.
684 Column causes the column number of the start of the event to be passed.
685 The first column on a line is 0.
689 Dtext causes the decoded text to be passed. General entities are
690 automatically decoded unless the event was inside a CDATA section or
691 was between literal start and end tags (C<script>, C<style>,
692 C<xmp>, C<iframe>, C<title>, C<textarea> and C<plaintext>).
694 The Unicode character set is assumed for entity decoding. With Perl
695 version 5.6 or earlier only the Latin-1 range is supported, and
696 entities for characters outside the range 0..255 are left unchanged.
698 This passes undef except for C<text> events.
702 Event causes the event name to be passed.
704 The event name is one of C<text>, C<start>, C<end>, C<declaration>,
705 C<comment>, C<process>, C<start_document> or C<end_document>.
709 Is_cdata causes a TRUE value to be passed if the event is inside a CDATA
710 section or between literal start and end tags (C<script>,
711 C<style>, C<xmp>, C<iframe>, C<title>, C<textarea> and C<plaintext>).
713 if the flag is FALSE for a text event, then you should normally
714 either use C<dtext> or decode the entities yourself before the text is
719 Length causes the number of bytes of the source text of the event to
724 Line causes the line number of the start of the event to be passed.
725 The first line in the document is 1. Line counting doesn't start
726 until at least one handler requests this value to be reported.
730 Offset causes the byte position in the HTML document of the start of
731 the event to be passed. The first byte in the document has offset 0.
735 Offset_end causes the byte position in the HTML document of the end of
736 the event to be passed. This is the same as C<offset> + C<length>.
740 Self causes the current object to be passed to the handler. If the
741 handler is a method, this must be the first element in the argspec.
743 An alternative to passing self as an argspec is to register closures
744 that capture $self by themselves as handlers. Unfortunately this
745 creates circular references which prevent the HTML::Parser object
746 from being garbage collected. Using the C<self> argspec avoids this
749 =item C<skipped_text>
751 Skipped_text returns the concatenated text of all the events that have
752 been skipped since the last time an event was reported. Events might
753 be skipped because no handler is registered for them or because some
754 filter applies. Skipped text also includes marked section markup,
755 since there are no events that can catch it.
757 If an C<"">-handler is registered for an event, then the text for this
758 event is not included in C<skipped_text>. Skipped text both before
759 and after the C<"">-event is included in the next reported
764 Same as C<tagname>, but prefixed with "/" if it belongs to an C<end>
765 event and "!" for a declaration. The C<tag> does not have any prefix
766 for C<start> events, and is in this case identical to C<tagname>.
770 This is the element name (or I<generic identifier> in SGML jargon) for
771 start and end tags. Since HTML is case insensitive, this name is
772 forced to lower case to ease string matching.
774 Since XML is case sensitive, the tagname case is not changed when
775 C<xml_mode> is enabled. The same happens if the C<case_sensitive> attribute
778 The declaration type of declaration elements is also passed as a tagname,
779 even if that is a bit strange.
780 In fact, in the current implementation tagname is
781 identical to C<token0> except that the name may be forced to lower case.
785 Token0 causes the original text of the first token string to be
786 passed. This should always be the same as $tokens->[0].
788 For C<declaration> events, this is the declaration type.
790 For C<start> and C<end> events, this is the tag name.
792 For C<process> and non-strict C<comment> events, this is everything
795 This passes undef if there are no tokens in the event.
799 Tokenpos causes a reference to an array of token positions to be
800 passed. For each string that appears in C<tokens>, this array
801 contains two numbers. The first number is the offset of the start of
802 the token in the original C<text> and the second number is the length
805 Boolean attributes in a C<start> event will have (0,0) for the
806 attribute value offset and length.
808 This passes undef if there are no tokens in the event (e.g., C<text>)
809 and for artificial C<end> events triggered by empty element tags.
811 If you are using these offsets and lengths to modify C<text>, you
812 should either work from right to left, or be very careful to calculate
813 the changes to the offsets.
817 Tokens causes a reference to an array of token strings to be passed.
818 The strings are exactly as they were found in the original text,
819 no decoding or case changes are applied.
821 For C<declaration> events, the array contains each word, comment, and
822 delimited string starting with the declaration type.
824 For C<comment> events, this contains each sub-comment. If
825 $p->strict_comments is disabled, there will be only one sub-comment.
827 For C<start> events, this contains the original tag name followed by
828 the attribute name/value pairs. The values of boolean attributes will
829 be either the value set by $p->boolean_attribute_value, or the
830 attribute name if no value has been set by
831 $p->boolean_attribute_value.
833 For C<end> events, this contains the original tag name (always one token).
835 For C<process> events, this contains the process instructions (always one
838 This passes C<undef> for C<text> events.
842 Text causes the source text (including markup element delimiters) to be
847 Pass an undefined value. Useful as padding where the same handler
848 routine is registered for multiple events.
852 A literal string of 0 to 255 characters enclosed
853 in single (') or double (") quotes is passed as entered.
857 The whole argspec string can be wrapped up in C<'@{...}'> to signal
858 that the resulting event array should be flattened. This only makes a
859 difference if an array reference is used as the handler target.
860 Consider this example:
862 $p->handler(text => [], 'text');
863 $p->handler(text => [], '@{text}']);
865 With two text events; C<"foo">, C<"bar">; then the first example will end
866 up with [["foo"], ["bar"]] and the second with ["foo", "bar"] in
867 the handler target array.
872 Handlers for the following events can be registered:
878 This event is triggered when a markup comment is recognized.
882 <!-- This is a comment -- -- So is this -->
886 This event is triggered when a I<markup declaration> is recognized.
888 For typical HTML documents, the only declaration you are
889 likely to find is <!DOCTYPE ...>.
893 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
894 "http://www.w3.org/TR/html40/strict.dtd">
896 DTDs inside <!DOCTYPE ...> will confuse HTML::Parser.
900 This event is triggered for events that do not have a specific
901 handler. You can set up a handler for this event to catch stuff you
902 did not want to catch explicitly.
906 This event is triggered when an end tag is recognized.
912 =item C<end_document>
914 This event is triggered when $p->eof is called and after any remaining
915 text is flushed. There is no document text associated with this event.
919 This event is triggered when a processing instructions markup is
922 The format and content of processing instructions are system and
923 application dependent.
927 <? HTML processing instructions >
928 <? XML processing instructions ?>
932 This event is triggered when a start tag is recognized.
936 <A HREF="http://www.perl.com/">
938 =item C<start_document>
940 This event is triggered before any other events for a new document. A
941 handler for it can be used to initialize stuff. There is no document
942 text associated with this event.
946 This event is triggered when plain text (characters) is recognized.
947 The text may contain multiple lines. A sequence of text may be broken
948 between several text events unless $p->unbroken_text is enabled.
950 The parser will make sure that it does not break a word or a sequence
951 of whitespace between two text events.
957 The C<HTML::Parser> can parse Unicode strings when running under
958 perl-5.8 or better. If Unicode is passed to $p->parse() then chunks
959 of Unicode will be reported to the handlers. The offset and length
960 argspecs will also report their position in terms of characters.
962 It is safe to parse raw undecoded UTF-8 if you either avoid decoding
963 entities and make sure to not use I<argspecs> that do, or enable the
964 C<utf8_mode> for the parser. Parsing of undecoded UTF-8 might be
965 useful when parsing from a file where you need the reported offsets
966 and lengths to match the byte offsets in the file.
968 If a filename is passed to $p->parse_file() then the file will be read
969 in binary mode. This will be fine if the file contains only ASCII or
970 Latin-1 characters. If the file contains UTF-8 encoded text then care
971 must be taken when decoding entities as described in the previous
972 paragraph, but better is to open the file with the UTF-8 layer so that
973 it is decoded properly:
975 open(my $fh, "<:utf8", "index.html") || die "...: $!";
978 If the file contains text encoded in a charset besides ASCII, Latin-1
979 or UTF-8 then decoding will always be needed.
981 =head1 VERSION 2 COMPATIBILITY
983 When an C<HTML::Parser> object is constructed with no arguments, a set
984 of handlers is automatically provided that is compatible with the old
985 HTML::Parser version 2 callback methods.
987 This is equivalent to the following method calls:
989 $p->handler(start => "start", "self, tagname, attr, attrseq, text");
990 $p->handler(end => "end", "self, tagname, text");
991 $p->handler(text => "text", "self, text, is_cdata");
992 $p->handler(process => "process", "self, token0, text");
993 $p->handler(comment =>
995 my($self, $tokens) = @_;
996 for (@$tokens) {$self->comment($_);}},
998 $p->handler(declaration =>
1001 $self->declaration(substr($_[0], 2, -1));},
1004 Setting up these handlers can also be requested with the "api_version =>
1005 2" constructor option.
1009 The C<HTML::Parser> class is subclassable. Parser objects are plain
1010 hashes and C<HTML::Parser> reserves only hash keys that start with
1011 "_hparser". The parser state can be set up by invoking the init()
1012 method, which takes the same arguments as new().
1016 The first simple example shows how you might strip out comments from
1017 an HTML document. We achieve this by setting up a comment handler that
1018 does nothing and a default handler that will print out anything else:
1021 HTML::Parser->new(default_h => [sub { print shift }, 'text'],
1023 )->parse_file(shift || die) || die $!;
1025 An alternative implementation is:
1028 HTML::Parser->new(end_document_h => [sub { print shift },
1031 )->parse_file(shift || die) || die $!;
1033 This will in most cases be much more efficient since only a single
1034 callback will be made.
1036 The next example prints out the text that is inside the <title>
1037 element of an HTML document. Here we start by setting up a start
1038 handler. When it sees the title start tag it enables a text handler
1039 that prints any text found and an end handler that will terminate
1040 parsing as soon as the title end tag is seen:
1042 use HTML::Parser ();
1046 return if shift ne "title";
1048 $self->handler(text => sub { print shift }, "dtext");
1049 $self->handler(end => sub { shift->eof if shift eq "title"; },
1053 my $p = HTML::Parser->new(api_version => 3);
1054 $p->handler( start => \&start_handler, "tagname,self");
1055 $p->parse_file(shift || die) || die $!;
1058 More examples are found in the F<eg/> directory of the C<HTML-Parser>
1059 distribution: the program C<hrefsub> shows how you can edit all links
1060 found in a document; the program C<htextsub> shows how to edit the text only; the
1061 program C<hstrip> shows how you can strip out certain tags/elements
1062 and/or attributes; and the program C<htext> show how to obtain the
1063 plain text, but not any script/style content.
1065 You can browse the F<eg/> directory online from the I<[Browse]> link on
1066 the http://search.cpan.org/~gaas/HTML-Parser/ page.
1070 The <style> and <script> sections do not end with the first "</", but
1071 need the complete corresponding end tag. The standard behaviour is
1072 not really practical.
1074 When the I<strict_comment> option is enabled, we still recognize
1075 comments where there is something other than whitespace between even
1076 and odd "--" markers.
1078 Once $p->boolean_attribute_value has been set, there is no way to
1079 restore the default behaviour.
1081 There is currently no way to get both quote characters
1082 into the same literal argspec.
1084 Empty tags, e.g. "<>" and "</>", are not recognized. SGML allows them
1085 to repeat the previous start tag or close the previous start tag
1088 NET tags, e.g. "code/.../" are not recognized. This is SGML
1089 shorthand for "<code>...</code>".
1091 Unclosed start or end tags, e.g. "<tt<b>...</b</tt>" are not
1096 The following messages may be produced by HTML::Parser. The notation
1097 in this listing is the same as used in L<perldiag>:
1101 =item Not a reference to a hash
1103 (F) The object blessed into or subclassed from HTML::Parser is not a
1104 hash as required by the HTML::Parser methods.
1106 =item Bad signature in parser state object at %p
1108 (F) The _hparser_xs_state element does not refer to a valid state structure.
1109 Something must have changed the internal value
1110 stored in this hash element, or the memory has been overwritten.
1112 =item _hparser_xs_state element is not a reference
1114 (F) The _hparser_xs_state element has been destroyed.
1116 =item Can't find '_hparser_xs_state' element in HTML::Parser hash
1118 (F) The _hparser_xs_state element is missing from the parser hash.
1119 It was either deleted, or not created when the object was created.
1121 =item API version %s not supported by HTML::Parser %s
1123 (F) The constructor option 'api_version' with an argument greater than
1124 or equal to 4 is reserved for future extensions.
1126 =item Bad constructor option '%s'
1128 (F) An unknown constructor option key was passed to the new() or
1131 =item Parse loop not allowed
1133 (F) A handler invoked the parse() or parse_file() method.
1134 This is not permitted.
1136 =item marked sections not supported
1138 (F) The $p->marked_sections() method was invoked in a HTML::Parser
1139 module that was compiled without support for marked sections.
1141 =item Unknown boolean attribute (%d)
1143 (F) Something is wrong with the internal logic that set up aliases for
1146 =item Only code or array references allowed as handler
1148 (F) The second argument for $p->handler must be either a subroutine
1149 reference, then name of a subroutine or method, or a reference to an
1152 =item No handler for %s events
1154 (F) The first argument to $p->handler must be a valid event name; i.e. one
1155 of "start", "end", "text", "process", "declaration" or "comment".
1157 =item Unrecognized identifier %s in argspec
1159 (F) The identifier is not a known argspec name.
1160 Use one of the names mentioned in the argspec section above.
1162 =item Literal string is longer than 255 chars in argspec
1164 (F) The current implementation limits the length of literals in
1165 an argspec to 255 characters. Make the literal shorter.
1167 =item Backslash reserved for literal string in argspec
1169 (F) The backslash character "\" is not allowed in argspec literals.
1170 It is reserved to permit quoting inside a literal in a later version.
1172 =item Unterminated literal string in argspec
1174 (F) The terminating quote character for a literal was not found.
1176 =item Bad argspec (%s)
1178 (F) Only identifier names, literals, spaces and commas
1179 are allowed in argspecs.
1181 =item Missing comma separator in argspec
1183 (F) Identifiers in an argspec must be separated with ",".
1185 =item Parsing of undecoded UTF-8 will give garbage when decoding entities
1187 (W) The first chunk parsed appears to contain undecoded UTF-8 and one
1188 or more argspecs that decode entities are used for the callback
1191 The result of decoding will be a mix of encoded and decoded characters
1192 for any entities that expand to characters with code above 127. This
1193 is not a good thing.
1195 The solution is to use the Encode::encode_utf8() on the data before
1196 feeding it to the $p->parse(). For $p->parse_file() pass a file that
1197 has been opened in ":utf8" mode.
1199 The parser can process raw undecoded UTF-8 sanely if the C<utf8_mode>
1200 is enabled or if the "attr", "@attr" or "dtext" argspecs is avoided.
1202 =item Parsing string decoded with wrong endianness
1204 (W) The first character in the document is U+FFFE. This is not a
1205 legal Unicode character but a byte swapped BOM. The result of parsing
1206 will likely be garbage.
1208 =item Parsing of undecoded UTF-32
1210 (W) The parser found the Unicode UTF-32 BOM signature at the start
1211 of the document. The result of parsing will likely be garbage.
1213 =item Parsing of undecoded UTF-16
1215 (W) The parser found the Unicode UTF-16 BOM signature at the start of
1216 the document. The result of parsing will likely be garbage.
1222 L<HTML::Entities>, L<HTML::PullParser>, L<HTML::TokeParser>, L<HTML::HeadParser>,
1223 L<HTML::LinkExtor>, L<HTML::Form>
1225 L<HTML::TreeBuilder> (part of the I<HTML-Tree> distribution)
1227 http://www.w3.org/TR/html4
1229 More information about marked sections and processing instructions may
1230 be found at C<http://www.sgml.u-net.com/book/sgml-8.htm>.
1234 Copyright 1996-2008 Gisle Aas. All rights reserved.
1235 Copyright 1999-2000 Michael A. Chase. All rights reserved.
1237 This library is free software; you can redistribute it and/or
1238 modify it under the same terms as Perl itself.