NAME

       XML::Checker::Parser - an XML::Parser that validates at parse time

SYNOPSIS

        use XML::Checker::Parser;

        my %expat_options = (KeepCDATA => 1,
                             Handlers => [ Unparsed => \&my_Unparsed_handler ]);
        my $parser = new XML::Checker::Parser (%expat_options);

        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 ...
        }

        # 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, @_);
        }

DESCRIPTION

       XML::Checker::Parser extends XML::Parser

       I hope the example in the SYNOPSIS says it all, just use XML::Checker::Parser as if it
       were an XML::Parser.  See XML::Parser for the supported (expat) options.

       You can also derive your parser from XML::Checker::Parser instead of from XML::Parser. All
       you should have to do is replace:

        package MyParser;
        @ISA = qw( XML::Parser );

       with:

        package MyParser;
        @ISA = qw( XML::Checker::Parser );

XML::Checker::Parser constructor

        $parser = new XML::Checker::Parser (SkipExternalDTD => 1, SkipInsignifWS => 1);

       The constructor takes the same parameters as XML::Parser with the following additions:

       SkipExternalDTD
           By default, it will try to load external DTDs using LWP. You can disable this by
           setting SkipExternalDTD to 1. See External DTDs for details.

       SkipInsignifWS
           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 "INSIGNIFICANT_WHITESPACE" in XML::Checker for
           details.

       LWP_UserAgent
           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 LWP::UserAgent
           that is created as follows:

            use LWP::UserAgent;
            $LWP_USER_AGENT = LWP::UserAgent->new;
            $LWP_USER_AGENT->env_proxy;

           Note that env_proxy 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:

            XML::Checker::Parser::set_LWP_UserAgent ($my_agent);

           or, you can specify it for a specific XML::Checker::Parser by passing it to the
           constructor:

            my $parser = new XML::Checker::Parser (LWP_UserAgent => $my_agent);

           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.

           The LWP modules are part of libwww-perl which is available at CPAN.

External DTDs

       XML::Checker::Parser will try to load and parse external DTDs that are referenced in
       DOCTYPE definitions unless you set the SkipExternalDTD option to 1 (the default setting is
       0.)  See CAVEATS for details on what is not supported by XML::Checker::Parser.

       XML::Parser (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 XML::Parser
       option ParseParamEnt to 1 and the XML::Checker::Parser option SkipExternalDTD to 1.  (They
       can both be set in the XML::Checker::Parser constructor.)

       When external DTDs are parsed by XML::Checker::Parser, they are located in the following
       order:

       •   With the %URI_MAP, which can be set using map_uri.  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.

             <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">

           However, you can also use this to force XML::Checker to read DTDs from a different URL
           than was specified (e.g. from the local file system for performance reasons.)

       •   on the Internet, if their system identifier starts with a protocol (like http://...)

       •   on the local disk, if their system identifier starts with a slash (absolute path)

       •   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 set_sgml_search_path(), 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.

   Static methods related to External DTDs
       set_sgml_search_path (dir1, dir2, ...)
           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".

           set_sgml_search_path is a static method.

       map_uri (pubid => uri, ...)
           To define the location of PUBLIC ids, as found in DOCTYPE declarations after the
           PUBLIC keyword, e.g.

             <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">

           call this method, e.g.

             XML::Checker::Parser::map_uri (
                   "-//W3C//DTD HTML 4.0//EN" => "file:/user/html.dtd");

           See External DTDs for more info.

           XML::Checker::Parser::map_uri is a static method.

Switching user handlers at parse time

       You should be able to use setHandlers() just as in XML::Parser.  (Using setHandlers has
       not been tested yet.)

Error handling

       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 "ERROR_HANDLING" in XML::Checker.)  It adds the
       (line, column, byte) information from XML::Parser to the error context (unless it was the
       end of the XML document.)

Supported XML::Parser handlers

       Only the following XML::Parser handlers are currently routed through XML::Checker: Init,
       Final, Char, Start, End, Element, Attlist, Doctype, Unparsed, Notation.

CAVEATS

       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.

AUTHOR

       Enno Derksen is the original author.

       Send bug reports, hints, tips, suggestions to T.J. Mather at <tjmather@tjmather.com>.

SEE ALSO

       XML::Checker ("SEE_ALSO" in XML::Checker), XML::Parser