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Parser(3) User Contributed Perl Documentation Parser(3)
NAME
HTML::Parser - HTML parser class
SYNOPSIS
use HTML::Parser ();
# Create parser object
$p = HTML::Parser->new( api_version => 3,
start_h => [\&start, "tagname, attr"],
end_h => [\&end, "tagname"],
marked_sections => 1,
);
# Parse document text chunk by chunk
$p->parse($chunk1);
$p->parse($chunk2);
#...
$p->eof; # signal end of document
# Parse directly from file
$p->parse_file("foo.html");
# or
open(my $fh, "<:utf8", "foo.html") ││ die;
$p->parse_file($fh);
DESCRIPTION
Objects of the "HTML::Parser" class will recognize markup and separate it from
plain text (alias data content) in HTML documents. As different kinds of markup
and text are recognized, the corresponding event handlers are invoked.
"HTML::Parser" is not a generic SGML parser. We have tried to make it able to deal
with the HTML that is actually "out there", and it normally parses as closely as
possible to the way the popular web browsers do it instead of strictly following
one of the many HTML specifications from W3C. Where there is disagreement, there
is often an option that you can enable to get the official behaviour.
The document to be parsed may be supplied in arbitrary chunks. This makes on-the-
fly parsing as documents are received from the network possible.
If event driven parsing does not feel right for your application, you might want to
use "HTML::PullParser". This is an "HTML::Parser" subclass that allows a more con-
ventional program structure.
METHODS
The following method is used to construct a new "HTML::Parser" object:
$p = HTML::Parser->new( %options_and_handlers )
This class method creates a new "HTML::Parser" object and returns it.
Key/value argument pairs may be provided to assign event handlers or initialize
parser options. The handlers and parser options can also be set or modified
later by the method calls described below.
If a top level key is in the form "<event>_h" (e.g., "text_h") then it assigns
a handler to that event, otherwise it initializes a parser option. The event
handler specification value must be an array reference. Multiple handlers may
also be assigned with the ’handlers => [%handlers]’ option. See examples
below.
If new() is called without any arguments, it will create a parser that uses
callback methods compatible with version 2 of "HTML::Parser". See the section
on "version 2 compatibility" below for details.
The special constructor option ’api_version => 2’ can be used to initialize
version 2 callbacks while still setting other options and handlers. The
’api_version => 3’ option can be used if you don’t want to set any options and
don’t want to fall back to v2 compatible mode.
Examples:
$p = HTML::Parser->new(api_version => 3,
text_h => [ sub {...}, "dtext" ]);
This creates a new parser object with a text event handler subroutine that
receives the original text with general entities decoded.
$p = HTML::Parser->new(api_version => 3,
start_h => [ ’my_start’, "self,tokens" ]);
This creates a new parser object with a start event handler method that
receives the $p and the tokens array.
$p = HTML::Parser->new(api_version => 3,
handlers => { text => [\@array, "event,text"],
comment => [\@array, "event,text"],
});
This creates a new parser object that stores the event type and the original
text in @array for text and comment events.
The following methods feed the HTML document to the "HTML::Parser" object:
$p->parse( $string )
Parse $string as the next chunk of the HTML document. The return value is nor-
mally a reference to the parser object (i.e. $p). Handlers invoked should not
attempt to modify the $string in-place until $p->parse returns.
If an invoked event handler aborts parsing by calling $p->eof, then $p->parse()
will return a FALSE value.
$p->parse( $code_ref )
If a code reference is passed as the argument to be parsed, then the chunks to
be parsed are obtained by invoking this function repeatedly. Parsing continues
until the function returns an empty (or undefined) result. When this happens
$p->eof is automatically signalled.
Parsing will also abort if one of the event handlers calls $p->eof.
The effect of this is the same as:
while (1) {
my $chunk = &$code_ref();
if (!defined($chunk) ││ !length($chunk)) {
$p->eof;
return $p;
}
$p->parse($chunk) ││ return undef;
}
But it is more efficient as this loop runs internally in XS code.
$p->parse_file( $file )
Parse text directly from a file. The $file argument can be a filename, an open
file handle, or a reference to an open file handle.
If $file contains a filename and the file can’t be opened, then the method
returns an undefined value and $! tells why it failed. Otherwise the return
value is a reference to the parser object.
If a file handle is passed as the $file argument, then the file will normally
be read until EOF, but not closed.
If an invoked event handler aborts parsing by calling $p->eof, then
$p->parse_file() may not have read the entire file.
On systems with multi-byte line terminators, the values passed for the offset
and length argspecs may be too low if parse_file() is called on a file handle
that is not in binary mode.
If a filename is passed in, then parse_file() will open the file in binary
mode.
$p->eof
Signals the end of the HTML document. Calling the $p->eof method outside a
handler callback will flush any remaining buffered text (which triggers the
"text" event if there is any remaining text).
Calling $p->eof inside a handler will terminate parsing at that point and cause
$p->parse to return a FALSE value. This also terminates parsing by
$p->parse_file().
After $p->eof has been called, the parse() and parse_file() methods can be
invoked to feed new documents with the parser object.
The return value from eof() is a reference to the parser object.
Most parser options are controlled by boolean attributes. Each boolean attribute
is enabled by calling the corresponding method with a TRUE argument and disabled
with a FALSE argument. The attribute value is left unchanged if no argument is
given. The return value from each method is the old attribute value.
Methods that can be used to get and/or set parser options are:
$p->attr_encoded
$p->attr_encoded( $bool )
By default, the "attr" and @attr argspecs will have general entities for
attribute values decoded. Enabling this attribute leaves entities alone.
$p->boolean_attribute_value( $val )
This method sets the value reported for boolean attributes inside HTML start
tags. By default, the name of the attribute is also used as its value. This
affects the values reported for "tokens" and "attr" argspecs.
$p->case_sensitive
$p->case_sensitive( $bool )
By default, tagnames and attribute names are down-cased. Enabling this
attribute leaves them as found in the HTML source document.
$p->closing_plaintext
$p->closing_plaintext( $bool )
By default, "plaintext" element can never be closed. Everything up to the end
of the document is parsed in CDATA mode. This historical behaviour is what at
least MSIE does. Enabling this attribute makes closing "</plaintext>" tag
effective and the parsing process will resume after seeing this tag. This emu-
lates gecko-based browsers.
$p->marked_sections
$p->marked_sections( $bool )
By default, section markings like <![CDATA[...]]> are treated like ordinary
text. When this attribute is enabled section markings are honoured.
There are currently no events associated with the marked section markup, but
the text can be returned as "skipped_text".
$p->strict_comment
$p->strict_comment( $bool )
By default, comments are terminated by the first occurrence of "-->". This is
the behaviour of most popular browsers (like Mozilla, Opera and MSIE), but it
is not correct according to the official HTML standard. Officially, you need
an even number of "--" tokens before the closing ">" is recognized and there
may not be anything but whitespace between an even and an odd "--".
The official behaviour is enabled by enabling this attribute.
Enabling of ’strict_comment’ also disables recognizing these forms as comments:
</ comment>
<! comment>
$p->strict_end
$p->strict_end( $bool )
By default, attributes and other junk are allowed to be present on end tags in
a manner that emulates MSIE’s behaviour.
The official behaviour is enabled with this attribute. If enabled, only
whitespace is allowed between the tagname and the final ">".
$p->strict_names
$p->strict_names( $bool )
By default, almost anything is allowed in tag and attribute names. This is the
behaviour of most popular browsers and allows us to parse some broken tags with
invalid attribute values like:
<IMG SRC=newprevlstGr.gif ALT=[PREV LIST] BORDER=0>
By default, "LIST]" is parsed as a boolean attribute, not as part of the ALT
value as was clearly intended. This is also what Mozilla sees.
The official behaviour is enabled by enabling this attribute. If enabled, it
will cause the tag above to be reported as text since "LIST]" is not a legal
attribute name.
$p->unbroken_text
$p->unbroken_text( $bool )
By default, blocks of text are given to the text handler as soon as possible
(but the parser takes care always to break text at a boundary between whites-
pace and non-whitespace so single words and entities can always be decoded
safely). This might create breaks that make it hard to do transformations on
the text. When this attribute is enabled, blocks of text are always reported in
one piece. This will delay the text event until the following (non-text) event
has been recognized by the parser.
Note that the "offset" argspec will give you the offset of the first segment of
text and "length" is the combined length of the segments. Since there might be
ignored tags in between, these numbers can’t be used to directly index in the
original document file.
$p->utf8_mode
$p->utf8_mode( $bool )
Enable this option when parsing raw undecoded UTF-8. This tells the parser
that the entities expanded for strings reported by "attr", @attr and "dtext"
should be expanded as decoded UTF-8 so they end up compatible with the sur-
rounding text.
If "utf8_mode" is enabled then it is an error to pass strings containing char-
acters with code above 255 to the parse() method, and the parse() method will
croak if you try.
Example: The Unicode character "\x{2665}" is "\xE2\x99\xA5" when UTF-8 encoded.
The character can also be represented by the entity "♥" or "♥".
If we feed the parser:
$p->parse("\xE2\x99\xA5♥");
then "dtext" will be reported as "\xE2\x99\xA5\x{2665}" without "utf8_mode"
enabled, but as "\xE2\x99\xA5\xE2\x99\xA5" when enabled. The later string is
what you want.
This option is only available with perl-5.8 or better.
$p->xml_mode
$p->xml_mode( $bool )
Enabling this attribute changes the parser to allow some XML constructs such as
empty element tags and XML processing instructions. It disables forcing tag
and attribute names to lower case when they are reported by the "tagname" and
"attr" argspecs, and suppresses special treatment of elements that are parsed
as CDATA for HTML.
Empty element tags look like start tags, but end with the character sequence
"/>". When recognized by "HTML::Parser" they cause an artificial end event in
addition to the start event. The "text" for the artificial end event will be
empty and the "tokenpos" array will be undefined even though the only element
in the token array will have the correct tag name.
XML processing instructions are terminated by "?>" instead of a simple ">" as
is the case for HTML.
As markup and text is recognized, handlers are invoked. The following method is
used to set up handlers for different events:
$p->handler( event => \&subroutine, $argspec )
$p->handler( event => $method_name, $argspec )
$p->handler( event => \@accum, $argspec )
$p->handler( event => "" );
$p->handler( event => undef );
$p->handler( event );
This method assigns a subroutine, method, or array to handle an event.
Event is one of "text", "start", "end", "declaration", "comment", "process",
"start_document", "end_document" or "default".
The "\&subroutine" is a reference to a subroutine which is called to handle the
event.
The $method_name is the name of a method of $p which is called to handle the
event.
The @accum is an array that will hold the event information as sub-arrays.
If the second argument is "", the event is ignored. If it is undef, the
default handler is invoked for the event.
The $argspec is a string that describes the information to be reported for the
event. Any requested information that does not apply to a specific event is
passed as "undef". If argspec is omitted, then it is left unchanged.
The return value from $p->handler is the old callback routine or a reference to
the accumulator array.
Any return values from handler callback routines/methods are always ignored. A
handler callback can request parsing to be aborted by invoking the $p->eof
method. A handler callback is not allowed to invoke the $p->parse() or
$p->parse_file() method. An exception will be raised if it tries.
Examples:
$p->handler(start => "start", ’self, attr, attrseq, text’ );
This causes the "start" method of object $p to be called for ’start’ events.
The callback signature is $p->start(\%attr, \@attr_seq, $text).
$p->handler(start => \&start, ’attr, attrseq, text’ );
This causes subroutine start() to be called for ’start’ events. The callback
signature is start(\%attr, \@attr_seq, $text).
$p->handler(start => \@accum, ’"S", attr, attrseq, text’ );
This causes ’start’ event information to be saved in @accum. The array ele-
ments will be [’S’, \%attr, \@attr_seq, $text].
$p->handler(start => "");
This causes ’start’ events to be ignored. It also suppresses invocations of
any default handler for start events. It is in most cases equivalent to
$p->handler(start => sub {}), but is more efficient. It is different from the
empty-sub-handler in that "skipped_text" is not reset by it.
$p->handler(start => undef);
This causes no handler to be associated with start events. If there is a
default handler it will be invoked.
Filters based on tags can be set up to limit the number of events reported. The
main bottleneck during parsing is often the huge number of callbacks made from the
parser. Applying filters can improve performance significantly.
The following methods control filters:
$p->ignore_elements( @tags )
Both the "start" event and the "end" event as well as any events that would be
reported in between are suppressed. The ignored elements can contain nested
occurrences of itself. Example:
$p->ignore_elements(qw(script style));
The "script" and "style" tags will always nest properly since their content is
parsed in CDATA mode. For most other tags "ignore_elements" must be used with
caution since HTML is often not well formed.
$p->ignore_tags( @tags )
Any "start" and "end" events involving any of the tags given are suppressed.
$p->report_tags( @tags )
Any "start" and "end" events involving any of the tags not given are sup-
pressed.
Argspec
Argspec is a string containing a comma-separated list that describes the informa-
tion reported by the event. The following argspec identifier names can be used:
"attr"
Attr causes a reference to a hash of attribute name/value pairs to be passed.
Boolean attributes’ values are either the value set by
$p->boolean_attribute_value, or the attribute name if no value has been set by
$p->boolean_attribute_value.
This passes undef except for "start" events.
Unless "xml_mode" or "case_sensitive" is enabled, the attribute names are
forced to lower case.
General entities are decoded in the attribute values and one layer of matching
quotes enclosing the attribute values is removed.
The Unicode character set is assumed for entity decoding. With Perl version
5.6 or earlier only the Latin-1 range is supported, and entities for characters
outside the range 0..255 are left unchanged.
@attr
Basically the same as "attr", but keys and values are passed as individual
arguments and the original sequence of the attributes is kept. The parameters
passed will be the same as the @attr calculated here:
@attr = map { $_ => $attr->{$_} } @$attrseq;
assuming $attr and $attrseq here are the hash and array passed as the result of
"attr" and "attrseq" argspecs.
This passes no values for events besides "start".
"attrseq"
Attrseq causes a reference to an array of attribute names to be passed. This
can be useful if you want to walk the "attr" hash in the original sequence.
This passes undef except for "start" events.
Unless "xml_mode" or "case_sensitive" is enabled, the attribute names are
forced to lower case.
"column"
Column causes the column number of the start of the event to be passed. The
first column on a line is 0.
"dtext"
Dtext causes the decoded text to be passed. General entities are automatically
decoded unless the event was inside a CDATA section or was between literal
start and end tags ("script", "style", "xmp", and "plaintext").
The Unicode character set is assumed for entity decoding. With Perl version
5.6 or earlier only the Latin-1 range is supported, and entities for characters
outside the range 0..255 are left unchanged.
This passes undef except for "text" events.
"event"
Event causes the event name to be passed.
The event name is one of "text", "start", "end", "declaration", "comment",
"process", "start_document" or "end_document".
"is_cdata"
Is_cdata causes a TRUE value to be passed if the event is inside a CDATA sec-
tion or between literal start and end tags ("script", "style", "xmp", and
"plaintext").
if the flag is FALSE for a text event, then you should normally either use
"dtext" or decode the entities yourself before the text is processed further.
"length"
Length causes the number of bytes of the source text of the event to be passed.
"line"
Line causes the line number of the start of the event to be passed. The first
line in the document is 1. Line counting doesn’t start until at least one han-
dler requests this value to be reported.
"offset"
Offset causes the byte position in the HTML document of the start of the event
to be passed. The first byte in the document has offset 0.
"offset_end"
Offset_end causes the byte position in the HTML document of the end of the
event to be passed. This is the same as "offset" + "length".
"self"
Self causes the current object to be passed to the handler. If the handler is
a method, this must be the first element in the argspec.
An alternative to passing self as an argspec is to register closures that cap-
ture $self by themselves as handlers. Unfortunately this creates circular ref-
erences which prevent the HTML::Parser object from being garbage collected.
Using the "self" argspec avoids this problem.
"skipped_text"
Skipped_text returns the concatenated text of all the events that have been
skipped since the last time an event was reported. Events might be skipped
because no handler is registered for them or because some filter applies.
Skipped text also includes marked section markup, since there are no events
that can catch it.
If an ""-handler is registered for an event, then the text for this event is
not included in "skipped_text". Skipped text both before and after the
""-event is included in the next reported "skipped_text".
"tag"
Same as "tagname", but prefixed with "/" if it belongs to an "end" event and
"!" for a declaration. The "tag" does not have any prefix for "start" events,
and is in this case identical to "tagname".
"tagname"
This is the element name (or generic identifier in SGML jargon) for start and
end tags. Since HTML is case insensitive, this name is forced to lower case to
ease string matching.
Since XML is case sensitive, the tagname case is not changed when "xml_mode" is
enabled. The same happens if the "case_sensitive" attribute is set.
The declaration type of declaration elements is also passed as a tagname, even
if that is a bit strange. In fact, in the current implementation tagname is
identical to "token0" except that the name may be forced to lower case.
"token0"
Token0 causes the original text of the first token string to be passed. This
should always be the same as $tokens->[0].
For "declaration" events, this is the declaration type.
For "start" and "end" events, this is the tag name.
For "process" and non-strict "comment" events, this is everything inside the
tag.
This passes undef if there are no tokens in the event.
"tokenpos"
Tokenpos causes a reference to an array of token positions to be passed. For
each string that appears in "tokens", this array contains two numbers. The
first number is the offset of the start of the token in the original "text" and
the second number is the length of the token.
Boolean attributes in a "start" event will have (0,0) for the attribute value
offset and length.
This passes undef if there are no tokens in the event (e.g., "text") and for
artificial "end" events triggered by empty element tags.
If you are using these offsets and lengths to modify "text", you should either
work from right to left, or be very careful to calculate the changes to the
offsets.
"tokens"
Tokens causes a reference to an array of token strings to be passed. The
strings are exactly as they were found in the original text, no decoding or
case changes are applied.
For "declaration" events, the array contains each word, comment, and delimited
string starting with the declaration type.
For "comment" events, this contains each sub-comment. If $p->strict_comments
is disabled, there will be only one sub-comment.
For "start" events, this contains the original tag name followed by the
attribute name/value pairs. The values of boolean attributes will be either
the value set by $p->boolean_attribute_value, or the attribute name if no value
has been set by $p->boolean_attribute_value.
For "end" events, this contains the original tag name (always one token).
For "process" events, this contains the process instructions (always one
token).
This passes "undef" for "text" events.
"text"
Text causes the source text (including markup element delimiters) to be passed.
"undef"
Pass an undefined value. Useful as padding where the same handler routine is
registered for multiple events.
’...’
A literal string of 0 to 255 characters enclosed in single (’) or double (")
quotes is passed as entered.
The whole argspec string can be wrapped up in ’@{...}’ to signal that the resulting
event array should be flattened. This only makes a difference if an array refer-
ence is used as the handler target. Consider this example:
$p->handler(text => [], ’text’);
$p->handler(text => [], ’@{text}’]);
With two text events; "foo", "bar"; then the first example will end up with
[["foo"], ["bar"]] and the second with ["foo", "bar"] in the handler target array.
Events
Handlers for the following events can be registered:
"comment"
This event is triggered when a markup comment is recognized.
Example:
<!-- This is a comment -- -- So is this -->
"declaration"
This event is triggered when a markup declaration is recognized.
For typical HTML documents, the only declaration you are likely to find is
<!DOCTYPE ...>.
Example:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html40/strict.dtd">
DTDs inside <!DOCTYPE ...> will confuse HTML::Parser.
"default"
This event is triggered for events that do not have a specific handler. You
can set up a handler for this event to catch stuff you did not want to catch
explicitly.
"end"
This event is triggered when an end tag is recognized.
Example:
</A>
"end_document"
This event is triggered when $p->eof is called and after any remaining text is
flushed. There is no document text associated with this event.
"process"
This event is triggered when a processing instructions markup is recognized.
The format and content of processing instructions are system and application
dependent.
Examples:
<? HTML processing instructions >
<? XML processing instructions ?>
"start"
This event is triggered when a start tag is recognized.
Example:
<A HREF="http://www.perl.com/">
"start_document"
This event is triggered before any other events for a new document. A handler
for it can be used to initialize stuff. There is no document text associated
with this event.
"text"
This event is triggered when plain text (characters) is recognized. The text
may contain multiple lines. A sequence of text may be broken between several
text events unless $p->unbroken_text is enabled.
The parser will make sure that it does not break a word or a sequence of
whitespace between two text events.
Unicode
The "HTML::Parser" can parse Unicode strings when running under perl-5.8 or better.
If Unicode is passed to $p->parse() then chunks of Unicode will be reported to the
handlers. The offset and length argspecs will also report their position in terms
of characters.
It is safe to parse raw undecoded UTF-8 if you either avoid decoding entities and
make sure to not use argspecs that do, or enable the "utf8_mode" for the parser.
Parsing of undecoded UTF-8 might be useful when parsing from a file where you need
the reported offsets and lengths to match the byte offsets in the file.
If a filename is passed to $p->parse_file() then the file will be read in binary
mode. This will be fine if the file contains only ASCII or Latin-1 characters. If
the file contains UTF-8 encoded text then care must be taken when decoding entities
as described in the previous paragraph, but better is to open the file with the
UTF-8 layer so that it is decoded properly:
open(my $fh, "<:utf8", "index.html") ││ die "...: $!";
$p->parse_file($fh);
If the file contains text encoded in a charset besides ASCII, Latin-1 or UTF-8 then
decoding will always be needed.
VERSION 2 COMPATIBILITY
When an "HTML::Parser" object is constructed with no arguments, a set of handlers
is automatically provided that is compatible with the old HTML::Parser version 2
callback methods.
This is equivalent to the following method calls:
$p->handler(start => "start", "self, tagname, attr, attrseq, text");
$p->handler(end => "end", "self, tagname, text");
$p->handler(text => "text", "self, text, is_cdata");
$p->handler(process => "process", "self, token0, text");
$p->handler(comment =>
sub {
my($self, $tokens) = @_;
for (@$tokens) {$self->comment($_);}},
"self, tokens");
$p->handler(declaration =>
sub {
my $self = shift;
$self->declaration(substr($_[0], 2, -1));},
"self, text");
Setting up these handlers can also be requested with the "api_version => 2" con-
structor option.
SUBCLASSING
The "HTML::Parser" class is subclassable. Parser objects are plain hashes and
"HTML::Parser" reserves only hash keys that start with "_hparser". The parser
state can be set up by invoking the init() method, which takes the same arguments
as new().
EXAMPLES
The first simple example shows how you might strip out comments from an HTML docu-
ment. We achieve this by setting up a comment handler that does nothing and a
default handler that will print out anything else:
use HTML::Parser;
HTML::Parser->new(default_h => [sub { print shift }, ’text’],
comment_h => [""],
)->parse_file(shift ││ die) ││ die $!;
An alternative implementation is:
use HTML::Parser;
HTML::Parser->new(end_document_h => [sub { print shift },
’skipped_text’],
comment_h => [""],
)->parse_file(shift ││ die) ││ die $!;
This will in most cases be much more efficient since only a single callback will be
made.
The next example prints out the text that is inside the <title> element of an HTML
document. Here we start by setting up a start handler. When it sees the title
start tag it enables a text handler that prints any text found and an end handler
that will terminate parsing as soon as the title end tag is seen:
use HTML::Parser ();
sub start_handler
{
return if shift ne "title";
my $self = shift;
$self->handler(text => sub { print shift }, "dtext");
$self->handler(end => sub { shift->eof if shift eq "title"; },
"tagname,self");
}
my $p = HTML::Parser->new(api_version => 3);
$p->handler( start => \&start_handler, "tagname,self");
$p->parse_file(shift ││ die) ││ die $!;
print "\n";
More examples are found in the eg/ directory of the "HTML-Parser" distribution: the
program "hrefsub" shows how you can edit all links found in a document; the program
"htextsub" shows how to edit the text only; the program "hstrip" shows how you can
strip out certain tags/elements and/or attributes; and the program "htext" show how
to obtain the plain text, but not any script/style content.
You can browse the eg/ directory online from the [Browse] link on the
http://search.cpan.org/~gaas/HTML-Parser/ page.
BUGS
The <style> and <script> sections do not end with the first "</", but need the com-
plete corresponding end tag. The standard behaviour is not really practical.
When the strict_comment option is enabled, we still recognize comments where there
is something other than whitespace between even and odd "--" markers.
Once $p->boolean_attribute_value has been set, there is no way to restore the
default behaviour.
There is currently no way to get both quote characters into the same literal
argspec.
Empty tags, e.g. "<>" and "</>", are not recognized. SGML allows them to repeat
the previous start tag or close the previous start tag respectively.
NET tags, e.g. "code/.../" are not recognized. This is SGML shorthand for
"<code>...</code>".
Unclosed start or end tags, e.g. "<tt<b>...</b</tt>" are not recognized.
DIAGNOSTICS
The following messages may be produced by HTML::Parser. The notation in this list-
ing is the same as used in perldiag:
Not a reference to a hash
(F) The object blessed into or subclassed from HTML::Parser is not a hash as
required by the HTML::Parser methods.
Bad signature in parser state object at %p
(F) The _hparser_xs_state element does not refer to a valid state structure.
Something must have changed the internal value stored in this hash element, or
the memory has been overwritten.
_hparser_xs_state element is not a reference
(F) The _hparser_xs_state element has been destroyed.
Can’t find ’_hparser_xs_state’ element in HTML::Parser hash
(F) The _hparser_xs_state element is missing from the parser hash. It was
either deleted, or not created when the object was created.
API version %s not supported by HTML::Parser %s
(F) The constructor option ’api_version’ with an argument greater than or equal
to 4 is reserved for future extentions.
Bad constructor option ’%s’
(F) An unknown constructor option key was passed to the new() or init() meth-
ods.
Parse loop not allowed
(F) A handler invoked the parse() or parse_file() method. This is not permit-
ted.
marked sections not supported
(F) The $p->marked_sections() method was invoked in a HTML::Parser module that
was compiled without support for marked sections.
Unknown boolean attribute (%d)
(F) Something is wrong with the internal logic that set up aliases for boolean
attributes.
Only code or array references allowed as handler
(F) The second argument for $p->handler must be either a subroutine reference,
then name of a subroutine or method, or a reference to an array.
No handler for %s events
(F) The first argument to $p->handler must be a valid event name; i.e. one of
"start", "end", "text", "process", "declaration" or "comment".
Unrecognized identifier %s in argspec
(F) The identifier is not a known argspec name. Use one of the names mentioned
in the argspec section above.
Literal string is longer than 255 chars in argspec
(F) The current implementation limits the length of literals in an argspec to
255 characters. Make the literal shorter.
Backslash reserved for literal string in argspec
(F) The backslash character "\" is not allowed in argspec literals. It is
reserved to permit quoting inside a literal in a later version.
Unterminated literal string in argspec
(F) The terminating quote character for a literal was not found.
Bad argspec (%s)
(F) Only identifier names, literals, spaces and commas are allowed in argspecs.
Missing comma separator in argspec
(F) Identifiers in an argspec must be separated with ",".
Parsing of undecoded UTF-8 will give garbage when decoding entities
(W) The first chunk parsed appears to contain undecoded UTF-8 and one or more
argspecs that decode entities are used for the callback handlers.
The result of decoding will be a mix of encoded and decoded characters for any
entities that expand to characters with code above 127. This is not a good
thing.
The solution is to use the Encode::encode_utf8() on the data before feeding it
to the $p->parse(). For $p->parse_file() pass a file that has been opened in
":utf8" mode.
The parser can process raw undecoded UTF-8 sanely if the "utf8_mode" is enabled
or if the "attr", "@attr" or "dtext" argspecs is avoided.
Parsing string decoded with wrong endianess
(W) The first character in the document is U+FFFE. This is not a legal Unicode
character but a byte swapped BOM. The result of parsing will likely be
garbage.
Parsing of undecoded UTF-32
(W) The parser found the Unicode UTF-32 BOM signature at the start of the docu-
ment. The result of parsing will likely be garbage.
Parsing of undecoded UTF-16
(W) The parser found the Unicode UTF-16 BOM signature at the start of the docu-
ment. The result of parsing will likely be garbage.
SEE ALSO
HTML::Entities, HTML::PullParser, HTML::TokeParser, HTML::HeadParser, HTML::LinkEx-
tor, HTML::Form
HTML::TreeBuilder (part of the HTML-Tree distribution)
http://www.w3.org/TR/html4
More information about marked sections and processing instructions may be found at
"http://www.sgml.u-net.com/book/sgml-8.htm".
COPYRIGHT
Copyright 1996-2004 Gisle Aas. All rights reserved.
Copyright 1999-2000 Michael A. Chase. All rights reserved.
This library is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.
perl v5.8.6 2003-10-10 Parser(3)
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