<HTML><HEAD><TITLE>XML::Checker::Parser - an XML::Parser that validates at parse time</TITLE></HEAD><BODY><H1><A NAME="NAME">NAME
</A></H1><P>XML::Checker::Parser - an XML::Parser that validates at parse time
<P><HR><H1><A NAME="SYNOPSIS">SYNOPSIS
</A></H1><PRE> use XML::Checker::Parser;
</PRE><PRE> my %expat_options = (KeepCDATA => 1,
Handlers => [ Unparsed => \&my_Unparsed_handler ]);
my $parser = new XML::Checker::Parser (%expat_options);
</PRE><PRE> eval {
local $XML::Checker::FAIL = \&my_fail;
$parser->parsefile ("fail.xml");
};
if ($@) {
# Either XML::Parser (expat) threw an exception or my_fail() died.
... your error handling code here ...
}
</PRE><PRE> # Throws an exception (with die) when an error is encountered, this
# will stop the parsing process.
# Don't die if a warning or info message is encountered, just print a message.
sub my_fail {
my $code = shift;
die XML::Checker::error_string ($code, @_) if $code < 200;
XML::Checker::print_error ($code, @_);
}
</PRE><P><HR><H1><A NAME="DESCRIPTION">DESCRIPTION
</A></H1><P>XML::Checker::Parser extends <A HREF="../Parser.html">XML::Parser</A>
<P>I hope the example in the SYNOPSIS says it all, just use
<A HREF="Parser.html">XML::Checker::Parser</A> as if it were an XML::Parser.
See <A HREF="../Parser.html">XML::Parser</A> for the supported (expat) options.
<P>You can also derive your parser from XML::Checker::Parser instead of
from XML::Parser. All you should have to do is replace:
<PRE> package MyParser;
@ISA = qw( XML::Parser );
</PRE><P>with:
<PRE> package MyParser;
@ISA = qw( XML::Checker::Parser );
</PRE><P><HR><H1><A NAME="XML_Checker_Parser_constructor">XML::Checker::Parser constructor
</A></H1><PRE> $parser = new XML::Checker::Parser (SkipExternalDTD => 1, SkipInsignifWS => 1);
</PRE><P>The constructor takes the same parameters as <A HREF="../Parser.html">XML::Parser</A> with the following additions:
<DL><DT><A NAME="SkipExternalDTD_"><STRONG><P>SkipExternalDTD
</STRONG></A><DD>By default, it will try to load external DTDs using LWP. You can disable this
by setting SkipExternalDTD to 1. See <A HREF="#External_DTDs">External DTDs</A> for details.
<DT><A NAME="SkipInsignifWS_"><STRONG><P>SkipInsignifWS
</STRONG></A><DD>By default, it will treat insignificant whitespace as regular Char data.
By setting SkipInsignifWS to 1, the user Char handler will not be called
if insignificant whitespace is encountered.
See <A HREF="../Checker.html#INSIGNIFICANT_WHITESPACE">XML::Checker/INSIGNIFICANT_WHITESPACE</A> for details.
<DT><A NAME="LWP_UserAgent_"><STRONG><P>LWP_UserAgent
</STRONG></A><DD>When calling parsefile() with a URL (instead of a filename) or when loading
external DTDs, we use LWP to download the
remote file. By default it will use a <A>LWP::UserAgent</A> that is created as follows:
<PRE> use LWP::UserAgent;
$LWP_USER_AGENT = LWP::UserAgent->new;
$LWP_USER_AGENT->env_proxy;
</PRE><P>Note that <A>env_proxy</A> reads proxy settings from your environment variables,
which is what I need to do to get thru our firewall.
If you want to use a different LWP::UserAgent, you can either set
it globally with:
<PRE> XML::Checker::Parser::set_LWP_UserAgent ($my_agent);
</PRE><P>or, you can specify it for a specific XML::Checker::Parser by passing it to
the constructor:
<PRE> my $parser = new XML::Checker::Parser (LWP_UserAgent => $my_agent);
</PRE><P>Currently, LWP is used when the filename (passed to parsefile) starts with one of
the following URL schemes: http, https, ftp, wais, gopher, or file
(followed by a colon.) If I missed one, please let me know.
<P>The LWP modules are part of libwww-perl which is available at CPAN.
</DL><P><HR><H1><A NAME="External_DTDs">External DTDs
</A></H1><P>XML::Checker::Parser will try to load and parse external DTDs that are
referenced in DOCTYPE definitions unless you set the <B>SkipExternalDTD</B>
option to 1 (the default setting is 0.)
See <A HREF="#CAVEATS">CAVEATS</A> for details on what is not supported by XML::Checker::Parser.
<P><A HREF="../Parser.html">XML::Parser</A> (version 2.27 and up) does a much better job at reading external
DTDs, because recently external DTD parsing was added to expat.
Make sure you set the <A HREF="../Parser.html">XML::Parser</A> option <B>ParseParamEnt</B> to 1 and the
XML::Checker::Parser option <B>SkipExternalDTD</B> to 1.
(They can both be set in the XML::Checker::Parser constructor.)
<P>When external DTDs are parsed by XML::Checker::Parser, they are
located in the following order:
<UL><LI><P>With the %URI_MAP, which can be set using <B>map_uri</B>.
This hash maps external resource ids (like system ID's and public ID's)
to full path URI's.
It was meant to aid in resolving PUBLIC IDs found in DOCTYPE declarations
after the PUBLIC keyword, e.g.
<PRE> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
</PRE><P>However, you can also use this to force <A HREF="../Checker.html">XML::Checker</A> to read DTDs from a
different URL than was specified (e.g. from the local file system for
performance reasons.)
<LI><P>on the Internet, if their system identifier starts with a protocol
(like http://...)
<LI><P>on the local disk, if their system identifier starts with a slash
(absolute path)
<LI><P>in the SGML_SEARCH_PATH, if their system identifier is a
relative file name. It will use @SGML_SEARCH_PATH if it was set with
<B>set_sgml_search_path()</B>, or the colon-separated $ENV{SGML_SEARCH_PATH},
or (if that isn't set) the list (".", "$ENV{'HOME'}/.sgml", "/usr/lib/sgml",
"/usr/share/sgml"), which includes the
current directory, so it should do the right thing in most cases.
</UL><H2><A NAME="Static_methods_related_to_External_DTDs">Static methods related to External DTDs
</A></H2><DL><DT><A NAME="set_sgml_search_path_dir1_dir2_"><STRONG><P>set_sgml_search_path (dir1, dir2, ...)
</STRONG></A><DD>External DTDs with relative file paths are looked up using the @SGML_SEARCH_PATH,
which can be set with this method. If @SGML_SEARCH_PATH is never set, it
will use the colon-separated $ENV{SGML_SEARCH_PATH} instead. If neither are set
it uses the list: ".", "$ENV{'HOME'}/.sgml", "/usr/lib/sgml",
"/usr/share/sgml".
<P>set_sgml_search_path is a static method.
<DT><A NAME="map_uri_pubid_uri_"><STRONG><P>map_uri (pubid => uri, ...)
</STRONG></A><DD>To define the location of PUBLIC ids, as found in DOCTYPE declarations
after the PUBLIC keyword, e.g.
<PRE> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
</PRE><P>call this method, e.g.
<PRE> XML::Checker::Parser::map_uri (
"-//W3C//DTD HTML 4.0//EN" => "file:/user/html.dtd");
</PRE><P>See <A HREF="#External_DTDs">External DTDs</A> for more info.
<P>XML::Checker::Parser::map_uri is a static method.
</DL><P><HR><H1><A NAME="Switching_user_handlers_at_parse_time">Switching user handlers at parse time
</A></H1><P>You should be able to use setHandlers() just as in <A HREF="../Parser.html">XML::Parser</A>.
(Using setHandlers has not been tested yet.)
<P><HR><H1><A NAME="Error_handling">Error handling
</A></H1><P>XML::Checker::Parser routes the fail handler through
XML::Checker::Parser::fail_add_context() before calling your fail handler
(i.e. the global fail handler: $XML::Checker::FAIL.
See <A HREF="../Checker.html#ERROR_HANDLING">XML::Checker/ERROR_HANDLING</A>.)
It adds the (line, column, byte) information from <A HREF="../Parser.html">XML::Parser</A> to the
error context (unless it was the end of the XML document.)
<P><HR><H1><A NAME="Supported_XML_Parser_handlers">Supported XML::Parser handlers
</A></H1><P>Only the following <A HREF="../Parser.html">XML::Parser</A> handlers are currently routed through
<A HREF="../Checker.html">XML::Checker</A>: Init, Final, Char, Start, End, Element, Attlist, Doctype,
Unparsed, Notation.
<P><HR><H1><A NAME="CAVEATS">CAVEATS
</A></H1><P>When using XML::Checker::Parser to parse external DTDs
(i.e. with SkipExternalDTD => 0),
expect trouble when your external DTD contains parameter entities inside
declarations or conditional sections. The external DTD should probably have
the same encoding as the orignal XML document.
<P><HR><H1><A NAME="AUTHOR">AUTHOR
</A></H1><P>Send bug reports, hints, tips, suggestions to Enno Derksen at
<<I>enno@att.com</I>>.
<P><HR><H1><A NAME="SEE_ALSO">SEE ALSO
</A></H1><P><A HREF="../Checker.html">XML::Checker</A> (<A HREF="../Checker.html#SEE_ALSO">XML::Checker/SEE_ALSO</A>), <A HREF="../Parser.html">XML::Parser</A>
<P><HR><I><FONT SIZE="-1">Last updated: Wed Feb 23 13:37:16 2000</FONT></I></BODY></HTML>