#

# Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

# All rights reserved.

# This component and the accompanying materials are made available

# under the terms of "Eclipse Public License v1.0"

# which accompanies this distribution, and is available

# at the URL "http://www.eclipse.org/legal/epl-v10.html".

#

# Initial Contributors:

# Nokia Corporation - initial contribution.

#

# Contributors:

#

# Description:

#

#-------------------------------------------------------------------------------

# package: SysDefParser

#

# usage: Wrapper for an XML parser to dispatch callbacks to a client object which

#    analyses the parsed XML data. The auxiliary package SysDefParser::Dispatcher

#    acts as an intermediary between the parser and the client to convert function

#    callbacks to method callbacks using perl's AUTOLOAD mechanism.

#

# public methods:

#

#    new(-client => <client reference>, [-parser => <package name>]) : creates a

#        instance. <client reference> is the instance to which the parser callbacks

#        are dispatched. <package name> is an optional alternative parser client

#        package to use instead of the default XML::Parser class.

#

#    parse(<fileh>): parse the XML data from filehandle <fileh> dispatching

#        callbacks to the client object.

#         

#-------------------------------------------------------------------------------

package SysDefParser;

use strict;

sub new

{

    my ($class, %args) = @_;

    my $self = bless {}, $class;

    $self->{client} = delete $args{-client};

    if (exists $args{-parser})

    {

        $args{Pkg} = 'SysDefParser::Dispatcher';

        require $args{-parser};

        $self->{parser} = $args{-parser}->createParser(%args);

    }

    else

    {

        $self->{parser} = $class->_createParser(%args);

    }

    return $self;

}

sub _createParser

{

    my ($class, %args) = @_;

    require XML::Parser;

    return XML::Parser->new

           (

               Style        => 'Subs',

               Pkg          => 'SysDefParser::Dispatcher',

               ErrorContext => 2

           );

}

my $PARSERCLIENT = undef;

sub _client { return $PARSERCLIENT; }

sub parse

{

    my ($self, $fileh) = @_;

    # we can't pass any context down to the underlying parser so that we can work out which

    # object any callbacks from the parser are associated with so, assuming that the parser will

    # not be called in a re-entrant fashion, we store the context at this point, so that we can

    # then dispatch the callbacks from the parsers 'parse' method to those methods of the saved

    # $PARSERCLIENT instance.

    die "Fatal: client object not set\n" if ! defined $self->{client};

    die "Fatal: parser client object already set\n" if defined $PARSERCLIENT;

    $PARSERCLIENT = $self->{client};

    # call the parser, callbacks will be dispatched to sub AUTOLOAD in SysDefParser::Dispatcher

    my $rv =$self->{parser}->parse($fileh);

    # finished parsing, unset the context

    $PARSERCLIENT = undef;

    return $rv;

}

#-------------------------------------------------------------------------------

# package SysDefParser::Dispatcher

#

# usage: Internal package. Uses AUTOLOAD mechanism to receive parser callbacks and

#    convert them to object method calls on teh client object.

#

#-------------------------------------------------------------------------------

package SysDefParser::Dispatcher;

use strict;

sub AUTOLOAD

{

    my @ARGS = @_;

    my $client = SysDefParser::_client();

    die "Fatal: parser client object not set\n" if ! defined $client;

    # translate the called back function name to the client method name

    my $clientpkg = ref($client);

    my $method = $SysDefParser::Dispatcher::AUTOLOAD;

    $method =~ s/^SysDefParser::Dispatcher/$clientpkg/;

    # dispatch the parser's callback to the client object (if implemented by client)

    $client->$method(@ARGS) if $client->can($method);

}

#-------------------------------------------------------------------------------

# -EOF-

#-------------------------------------------------------------------------------

1;