html::parser.3

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

would be reported in between are suppressed.  The ignored elements can
contain nested occurrences of itself.  Example:
.Sp
.Vb 1
\&   $p\->ignore_elements(qw(script style));
.Ve
.Sp
The \f(CW\*(C`script\*(C'\fR and \f(CW\*(C`style\*(C'\fR tags will always nest properly since their
content is parsed in \s-1CDATA\s0 mode.  For most other tags
\&\f(CW\*(C`ignore_elements\*(C'\fR must be used with caution since \s-1HTML\s0 is often not
\&\fIwell formed\fR.
.ie n .IP "$p\fR\->ignore_tags( \f(CW@tags )" 4
.el .IP "\f(CW$p\fR\->ignore_tags( \f(CW@tags\fR )" 4
.IX Item "$p->ignore_tags( @tags )"
Any \f(CW\*(C`start\*(C'\fR and \f(CW\*(C`end\*(C'\fR events involving any of the tags given are
suppressed.  To reset the filter (i.e. don't suppress any \f(CW\*(C`start\*(C'\fR and
\&\f(CW\*(C`end\*(C'\fR events), call \f(CW\*(C`ignore_tags\*(C'\fR without an argument.
.ie n .IP "$p\fR\->report_tags( \f(CW@tags )" 4
.el .IP "\f(CW$p\fR\->report_tags( \f(CW@tags\fR )" 4
.IX Item "$p->report_tags( @tags )"
Any \f(CW\*(C`start\*(C'\fR and \f(CW\*(C`end\*(C'\fR events involving any of the tags \fInot\fR given
are suppressed.  To reset the filter (i.e. report all \f(CW\*(C`start\*(C'\fR and
\&\f(CW\*(C`end\*(C'\fR events), call \f(CW\*(C`report_tags\*(C'\fR without an argument.
.PP
Internally, the system has two filter lists, one for \f(CW\*(C`report_tags\*(C'\fR
and one for \f(CW\*(C`ignore_tags\*(C'\fR, and both filters are applied.  This
effectively gives \f(CW\*(C`ignore_tags\*(C'\fR precedence over \f(CW\*(C`report_tags\*(C'\fR.
.PP
Examples:
.PP
.Vb 2
\&   $p\->ignore_tags(qw(style));
\&   $p\->report_tags(qw(script style));
.Ve
.PP
results in only \f(CW\*(C`script\*(C'\fR events being reported.
.Sh "Argspec"
.IX Subsection "Argspec"
Argspec is a string containing a comma-separated list that describes
the information reported by the event.  The following argspec
identifier names can be used:
.ie n .IP """attr""" 4
.el .IP "\f(CWattr\fR" 4
.IX Item "attr"
Attr causes a reference to a hash of attribute name/value pairs to be
passed.
.Sp
Boolean attributes' values are either the value set by
\&\f(CW$p\fR\->boolean_attribute_value, or the attribute name if no value has been
set by \f(CW$p\fR\->boolean_attribute_value.
.Sp
This passes undef except for \f(CW\*(C`start\*(C'\fR events.
.Sp
Unless \f(CW\*(C`xml_mode\*(C'\fR or \f(CW\*(C`case_sensitive\*(C'\fR is enabled, the attribute
names are forced to lower case.
.Sp
General entities are decoded in the attribute values and
one layer of matching quotes enclosing the attribute values is removed.
.Sp
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.
.ie n .IP "@attr" 4
.el .IP "\f(CW@attr\fR" 4
.IX Item "@attr"
Basically the same as \f(CW\*(C`attr\*(C'\fR, 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 \f(CW@attr\fR calculated
here:
.Sp
.Vb 1
\&   @attr = map { $_ => $attr\->{$_} } @$attrseq;
.Ve
.Sp
assuming \f(CW$attr\fR and \f(CW$attrseq\fR here are the hash and array passed as the
result of \f(CW\*(C`attr\*(C'\fR and \f(CW\*(C`attrseq\*(C'\fR argspecs.
.Sp
This passes no values for events besides \f(CW\*(C`start\*(C'\fR.
.ie n .IP """attrseq""" 4
.el .IP "\f(CWattrseq\fR" 4
.IX Item "attrseq"
Attrseq causes a reference to an array of attribute names to be
passed.  This can be useful if you want to walk the \f(CW\*(C`attr\*(C'\fR hash in
the original sequence.
.Sp
This passes undef except for \f(CW\*(C`start\*(C'\fR events.
.Sp
Unless \f(CW\*(C`xml_mode\*(C'\fR or \f(CW\*(C`case_sensitive\*(C'\fR is enabled, the attribute
names are forced to lower case.
.ie n .IP """column""" 4
.el .IP "\f(CWcolumn\fR" 4
.IX Item "column"
Column causes the column number of the start of the event to be passed.
The first column on a line is 0.
.ie n .IP """dtext""" 4
.el .IP "\f(CWdtext\fR" 4
.IX Item "dtext"
Dtext causes the decoded text to be passed.  General entities are
automatically decoded unless the event was inside a \s-1CDATA\s0 section or
was between literal start and end tags (\f(CW\*(C`script\*(C'\fR, \f(CW\*(C`style\*(C'\fR,
\&\f(CW\*(C`xmp\*(C'\fR, and \f(CW\*(C`plaintext\*(C'\fR).
.Sp
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.
.Sp
This passes undef except for \f(CW\*(C`text\*(C'\fR events.
.ie n .IP """event""" 4
.el .IP "\f(CWevent\fR" 4
.IX Item "event"
Event causes the event name to be passed.
.Sp
The event name is one of \f(CW\*(C`text\*(C'\fR, \f(CW\*(C`start\*(C'\fR, \f(CW\*(C`end\*(C'\fR, \f(CW\*(C`declaration\*(C'\fR,
\&\f(CW\*(C`comment\*(C'\fR, \f(CW\*(C`process\*(C'\fR, \f(CW\*(C`start_document\*(C'\fR or \f(CW\*(C`end_document\*(C'\fR.
.ie n .IP """is_cdata""" 4
.el .IP "\f(CWis_cdata\fR" 4
.IX Item "is_cdata"
Is_cdata causes a \s-1TRUE\s0 value to be passed if the event is inside a \s-1CDATA\s0
section or between literal start and end tags (\f(CW\*(C`script\*(C'\fR,
\&\f(CW\*(C`style\*(C'\fR, \f(CW\*(C`xmp\*(C'\fR, and \f(CW\*(C`plaintext\*(C'\fR).
.Sp
if the flag is \s-1FALSE\s0 for a text event, then you should normally
either use \f(CW\*(C`dtext\*(C'\fR or decode the entities yourself before the text is
processed further.
.ie n .IP """length""" 4
.el .IP "\f(CWlength\fR" 4
.IX Item "length"
Length causes the number of bytes of the source text of the event to
be passed.
.ie n .IP """line""" 4
.el .IP "\f(CWline\fR" 4
.IX Item "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 handler requests this value to be reported.
.ie n .IP """offset""" 4
.el .IP "\f(CWoffset\fR" 4
.IX Item "offset"
Offset causes the byte position in the \s-1HTML\s0 document of the start of
the event to be passed.  The first byte in the document has offset 0.
.ie n .IP """offset_end""" 4
.el .IP "\f(CWoffset_end\fR" 4
.IX Item "offset_end"
Offset_end causes the byte position in the \s-1HTML\s0 document of the end of
the event to be passed.  This is the same as \f(CW\*(C`offset\*(C'\fR + \f(CW\*(C`length\*(C'\fR.
.ie n .IP """self""" 4
.el .IP "\f(CWself\fR" 4
.IX Item "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.
.Sp
An alternative to passing self as an argspec is to register closures
that capture \f(CW$self\fR by themselves as handlers.  Unfortunately this
creates circular references which prevent the HTML::Parser object
from being garbage collected.  Using the \f(CW\*(C`self\*(C'\fR argspec avoids this
problem.
.ie n .IP """skipped_text""" 4
.el .IP "\f(CWskipped_text\fR" 4
.IX Item "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.
.Sp
If an \f(CW""\fR\-handler is registered for an event, then the text for this
event is not included in \f(CW\*(C`skipped_text\*(C'\fR.  Skipped text both before
and after the \f(CW""\fR\-event is included in the next reported
\&\f(CW\*(C`skipped_text\*(C'\fR.
.ie n .IP """tag""" 4
.el .IP "\f(CWtag\fR" 4
.IX Item "tag"
Same as \f(CW\*(C`tagname\*(C'\fR, but prefixed with \*(L"/\*(R" if it belongs to an \f(CW\*(C`end\*(C'\fR
event and \*(L"!\*(R" for a declaration.  The \f(CW\*(C`tag\*(C'\fR does not have any prefix
for \f(CW\*(C`start\*(C'\fR events, and is in this case identical to \f(CW\*(C`tagname\*(C'\fR.
.ie n .IP """tagname""" 4
.el .IP "\f(CWtagname\fR" 4
.IX Item "tagname"
This is the element name (or \fIgeneric identifier\fR in \s-1SGML\s0 jargon) for
start and end tags.  Since \s-1HTML\s0 is case insensitive, this name is
forced to lower case to ease string matching.
.Sp
Since \s-1XML\s0 is case sensitive, the tagname case is not changed when
\&\f(CW\*(C`xml_mode\*(C'\fR is enabled.  The same happens if the \f(CW\*(C`case_sensitive\*(C'\fR attribute
is set.
.Sp
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 \f(CW\*(C`token0\*(C'\fR except that the name may be forced to lower case.
.ie n .IP """token0""" 4
.el .IP "\f(CWtoken0\fR" 4
.IX Item "token0"
Token0 causes the original text of the first token string to be
passed.  This should always be the same as \f(CW$tokens\fR\->[0].
.Sp
For \f(CW\*(C`declaration\*(C'\fR events, this is the declaration type.
.Sp
For \f(CW\*(C`start\*(C'\fR and \f(CW\*(C`end\*(C'\fR events, this is the tag name.
.Sp
For \f(CW\*(C`process\*(C'\fR and non-strict \f(CW\*(C`comment\*(C'\fR events, this is everything
inside the tag.
.Sp
This passes undef if there are no tokens in the event.
.ie n .IP """tokenpos""" 4
.el .IP "\f(CWtokenpos\fR" 4
.IX Item "tokenpos"
Tokenpos causes a reference to an array of token positions to be
passed.  For each string that appears in \f(CW\*(C`tokens\*(C'\fR, this array
contains two numbers.  The first number is the offset of the start of
the token in the original \f(CW\*(C`text\*(C'\fR and the second number is the length
of the token.
.Sp
Boolean attributes in a \f(CW\*(C`start\*(C'\fR event will have (0,0) for the
attribute value offset and length.
.Sp
This passes undef if there are no tokens in the event (e.g., \f(CW\*(C`text\*(C'\fR)
and for artificial \f(CW\*(C`end\*(C'\fR events triggered by empty element tags.
.Sp
If you are using these offsets and lengths to modify \f(CW\*(C`text\*(C'\fR, you
should either work from right to left, or be very careful to calculate
the changes to the offsets.
.ie n .IP """tokens""" 4
.el .IP "\f(CWtokens\fR" 4
.IX Item "tokens"
Tokens causes a reference to an array of token strings to be passed.
The strings are exactly as they were found in the original text,
no decoding or case changes are applied.
.Sp
For \f(CW\*(C`declaration\*(C'\fR events, the array contains each word, comment, and
delimited string starting with the declaration type.
.Sp
For \f(CW\*(C`comment\*(C'\fR events, this contains each sub-comment.  If
\&\f(CW$p\fR\->strict_comments is disabled, there will be only one sub-comment.
.Sp
For \f(CW\*(C`start\*(C'\fR 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 \f(CW$p\fR\->boolean_attribute_value, or the
attribute name if no value has been set by
\&\f(CW$p\fR\->boolean_attribute_value.
.Sp
For \f(CW\*(C`end\*(C'\fR events, this contains the original tag name (always one token).
.Sp
For \f(CW\*(C`process\*(C'\fR events, this contains the process instructions (always one
token).
.Sp
This passes \f(CW\*(C`undef\*(C'\fR for \f(CW\*(C`text\*(C'\fR events.
.ie n .IP """text""" 4
.el .IP "\f(CWtext\fR" 4
.IX Item "text"
Text causes the source text (including markup element delimiters) to be
passed.
.ie n .IP """undef""" 4
.el .IP "\f(CWundef\fR" 4
.IX Item "undef"
Pass an undefined value.  Useful as padding where the same handler
routine is registered for multiple events.
.ie n .IP "\*(Aq...\*(Aq" 4
.el .IP "\f(CW\*(Aq...\*(Aq\fR" 4
.IX Item "..."
A literal string of 0 to 255 characters enclosed
in single (') or double (") quotes is passed as entered.
.PP
The whole argspec string can be wrapped up in \f(CW\*(Aq@{...}\*(Aq\fR to signal
that the resulting event array should be flattened.  This only makes a
difference if an array reference is used as the handler target.
Consider this example:
.PP
.Vb 2
\&   $p\->handler(text => [], \*(Aqtext\*(Aq);
\&   $p\->handler(text => [], \*(Aq@{text}\*(Aq]);
.Ve
.PP
With two text events; \f(CW"foo"\fR, \f(CW"bar"\fR; then the first example will end
up with [[\*(L"foo\*(R"], [\*(L"bar\*(R"]] and the second with [\*(L"foo\*(R", \*(L"bar\*(R"] in
the handler target array.
.Sh "Events"
.IX Subsection "Events"
Handlers for the following events can be registered:
.ie n .IP """comment""" 4
.el .IP "\f(CWcomment\fR" 4
.IX Item "comment"
This event is triggered when a markup comment is recognized.
.Sp
Example:
.Sp
.Vb 1
\&  <!\-\- This is a comment \-\- \-\- So is this \-\->
.Ve
.ie n .IP """declaration""" 4
.el .IP "\f(CWdeclaration\fR" 4
.IX Item "declaration"
This event is triggered when a \fImarkup declaration\fR is recognized.
.Sp
For typical \s-1HTML\s0 documents, the only declaration you are
likely to find is <!DOCTYPE ...>.
.Sp
Example:
.Sp
.Vb 2
\&  <!DOCTYPE HTML PUBLIC "\-//W3C//DTD HTML 4.01//EN"
\&  "http://www.w3.org/TR/html40/strict.dtd">
.Ve
.Sp
DTDs inside <!DOCTYPE ...> will confuse HTML::Parser.
.ie n .IP """default""" 4
.el .IP "\f(CWdefault\fR" 4
.IX Item "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.
.ie n .IP """end""" 4
.el .IP "\f(CWend\fR" 4
.IX Item "end"
This event is triggered when an end tag is recognized.
.Sp
Example:
.Sp