###

# XML::NamespaceSupport - a simple generic namespace processor

# Robin Berjon <robin@knowscape.com>

###

package XML::NamespaceSupport;

use strict;

use constant FATALS         => 0; # root object

use constant NSMAP          => 1;

use constant UNKNOWN_PREF   => 2;

use constant AUTO_PREFIX    => 3;

use constant DEFAULT        => 0; # maps

use constant PREFIX_MAP     => 1;

use constant DECLARATIONS   => 2;

use vars qw($VERSION $NS_XMLNS $NS_XML);

$VERSION    = '1.07';

$NS_XMLNS   = 'http://www.w3.org/2000/xmlns/';

$NS_XML     = 'http://www.w3.org/XML/1998/namespace';

# add the ns stuff that baud wants based on Java's xml-writer

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

# constructor

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

sub new {

    my $class   = ref($_[0]) ? ref(shift) : shift;

    my $options = shift;

    my $self = [

                1, # FATALS

                [[ # NSMAP

                  undef,              # DEFAULT

                  { xml => $NS_XML }, # PREFIX_MAP

                  undef,              # DECLARATIONS

                ]],

                'aaa', # UNKNOWN_PREF

                0,     # AUTO_PREFIX

               ];

    $self->[NSMAP]->[0]->[PREFIX_MAP]->{xmlns} = $NS_XMLNS if $options->{xmlns};

    $self->[FATALS] = $options->{fatal_errors} if defined $options->{fatal_errors};

    $self->[AUTO_PREFIX] = $options->{auto_prefix} if defined $options->{auto_prefix};

    return bless $self, $class;

}

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

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

# reset() - return to the original state (for reuse)

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

sub reset {

    my $self = shift;

    $#{$self->[NSMAP]} = 0;

}

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

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

# push_context() - add a new empty context to the stack

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

sub push_context {

    my $self = shift;

    push @{$self->[NSMAP]}, [

                             $self->[NSMAP]->[-1]->[DEFAULT],

                             { %{$self->[NSMAP]->[-1]->[PREFIX_MAP]} },

                             [],

                            ];

}

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

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

# pop_context() - remove the topmost context fromt the stack

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

sub pop_context {

    my $self = shift;

    die 'Trying to pop context without push context' unless @{$self->[NSMAP]} > 1;

    pop @{$self->[NSMAP]};

}

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

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

# declare_prefix() - declare a prefix in the current scope

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

sub declare_prefix {

    my $self    = shift;

    my $prefix  = shift;

    my $value   = shift;

    warn <<'    EOWARN' unless defined $prefix or $self->[AUTO_PREFIX];

    Prefix was undefined.

    If you wish to set the default namespace, use the empty string ''.

    If you wish to autogenerate prefixes, set the auto_prefix option

    to a true value.

    EOWARN

    return 0 if index(lc($prefix), 'xml') == 0;

    if (defined $prefix and $prefix eq '') {

        $self->[NSMAP]->[-1]->[DEFAULT] = $value;

    }

    else {

        die "Cannot undeclare prefix $prefix" if $value eq '';

        if (not defined $prefix and $self->[AUTO_PREFIX]) {

            while (1) {

                $prefix = $self->[UNKNOWN_PREF]++;

                last if not exists $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$prefix};

            }

        }

        elsif (not defined $prefix and not $self->[AUTO_PREFIX]) {

            return 0;

        }

        $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$prefix} = $value;

    }

    push @{$self->[NSMAP]->[-1]->[DECLARATIONS]}, $prefix;

    return 1;

}

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

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

# declare_prefixes() - declare several prefixes in the current scope

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

sub declare_prefixes {

    my $self     = shift;

    my %prefixes = @_;

    while (my ($k,$v) = each %prefixes) {

        $self->declare_prefix($k,$v);

    }

}

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

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

# undeclare_prefix

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

sub undeclare_prefix {

    my $self   = shift;

    my $prefix = shift;

    return unless not defined $prefix or $prefix eq '';

    return unless exists $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$prefix};

    my ( $tfix ) = grep { $_ eq $prefix } @{$self->[NSMAP]->[-1]->[DECLARATIONS]};

    if ( not defined $tfix ) {

        die "prefix $prefix not declared in this context\n";

    }

    @{$self->[NSMAP]->[-1]->[DECLARATIONS]} = grep { $_ ne $prefix } @{$self->[NSMAP]->[-1]->[DECLARATIONS]};

    delete $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$prefix};

}

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

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

# get_prefix() - get a (random) prefix for a given URI

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

sub get_prefix {

    my $self    = shift;

    my $uri     = shift;

    # we have to iterate over the whole hash here because if we don't

    # the iterator isn't reset and the next pass will fail

    my $pref;

    while (my ($k, $v) = each %{$self->[NSMAP]->[-1]->[PREFIX_MAP]}) {

        $pref = $k if $v eq $uri;

    }

    return $pref;

}

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

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

# get_prefixes() - get all the prefixes for a given URI

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

sub get_prefixes {

    my $self    = shift;

    my $uri     = shift;

    return keys %{$self->[NSMAP]->[-1]->[PREFIX_MAP]} unless defined $uri;

    return grep { $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$_} eq $uri } keys %{$self->[NSMAP]->[-1]->[PREFIX_MAP]};

}

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

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

# get_declared_prefixes() - get all prefixes declared in the last context

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

sub get_declared_prefixes {

    return @{$_[0]->[NSMAP]->[-1]->[DECLARATIONS]};

}

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

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

# get_uri() - get an URI given a prefix

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

sub get_uri {

    my $self    = shift;

    my $prefix  = shift;

    warn "Prefix must not be undef in get_uri(). The emtpy prefix must be ''" unless defined $prefix;

    return $self->[NSMAP]->[-1]->[DEFAULT] if $prefix eq '';

    return $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$prefix} if exists $self->[NSMAP]->[-1]->[PREFIX_MAP]->{$prefix};

    return undef;

}

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

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

# process_name() - provide details on a name

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

sub process_name {

    my $self    = shift;

    my $qname   = shift;

    my $aflag   = shift;

    if ($self->[FATALS]) {

        return( ($self->_get_ns_details($qname, $aflag))[0,2], $qname );

    }

    else {

        eval { return( ($self->_get_ns_details($qname, $aflag))[0,2], $qname ); }

    }

}

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

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

# process_element_name() - provide details on a element's name

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

sub process_element_name {

    my $self    = shift;

    my $qname   = shift;

    if ($self->[FATALS]) {

        return $self->_get_ns_details($qname, 0);

    }

    else {

        eval { return $self->_get_ns_details($qname, 0); }

    }

}

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

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

# process_attribute_name() - provide details on a attribute's name

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

sub process_attribute_name {

    my $self    = shift;

    my $qname   = shift;

    if ($self->[FATALS]) {

        return $self->_get_ns_details($qname, 1);

    }

    else {

        eval { return $self->_get_ns_details($qname, 1); }

    }

}

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

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

# ($ns, $prefix, $lname) = $self->_get_ns_details($qname, $f_attr)

# returns ns, prefix, and lname for a given attribute name

# >> the $f_attr flag, if set to one, will work for an attribute

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

sub _get_ns_details {

    my $self    = shift;

    my $qname   = shift;

    my $aflag   = shift;

    my ($ns, $prefix, $lname);

    (my ($tmp_prefix, $tmp_lname) = split /:/, $qname, 3)

                                    < 3 or die "Invalid QName: $qname";

    # no prefix

    my $cur_map = $self->[NSMAP]->[-1];

    if (not defined($tmp_lname)) {

        $prefix = undef;

        $lname = $qname;

        # attr don't have a default namespace

        $ns = ($aflag) ? undef : $cur_map->[DEFAULT];

    }

    # prefix

    else {

        if (exists $cur_map->[PREFIX_MAP]->{$tmp_prefix}) {

            $prefix = $tmp_prefix;

            $lname  = $tmp_lname;

            $ns     = $cur_map->[PREFIX_MAP]->{$prefix}

        }

        else { # no ns -> lname == name, all rest undef

            die "Undeclared prefix: $tmp_prefix";

        }

    }

    return ($ns, $prefix, $lname);

}

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

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

# parse_jclark_notation() - parse the Clarkian notation

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

sub parse_jclark_notation {

    shift;

    my $jc = shift;

    $jc =~ m/^\{(.*)\}([^}]+)$/;

    return $1, $2;

}

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

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

# Java names mapping

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

*XML::NamespaceSupport::pushContext          = \&push_context;

*XML::NamespaceSupport::popContext           = \&pop_context;

*XML::NamespaceSupport::declarePrefix        = \&declare_prefix;

*XML::NamespaceSupport::declarePrefixes      = \&declare_prefixes;

*XML::NamespaceSupport::getPrefix            = \&get_prefix;

*XML::NamespaceSupport::getPrefixes          = \&get_prefixes;

*XML::NamespaceSupport::getDeclaredPrefixes  = \&get_declared_prefixes;

*XML::NamespaceSupport::getURI               = \&get_uri;

*XML::NamespaceSupport::processName          = \&process_name;

*XML::NamespaceSupport::processElementName   = \&process_element_name;

*XML::NamespaceSupport::processAttributeName = \&process_attribute_name;

*XML::NamespaceSupport::parseJClarkNotation  = \&parse_jclark_notation;

*XML::NamespaceSupport::undeclarePrefix      = \&undeclare_prefix;

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

1;

#,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,#

#`,`, Documentation `,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,`,#

#```````````````````````````````````````````````````````````````````#

=pod

=head1 NAME

XML::NamespaceSupport - a simple generic namespace support class

=head1 SYNOPSIS

  use XML::NamespaceSupport;

  my $nsup = XML::NamespaceSupport->new;

  # add a new empty context

  $nsup->push_context;

  # declare a few prefixes

  $nsup->declare_prefix($prefix1, $uri1);

  $nsup->declare_prefix($prefix2, $uri2);

  # the same shorter

  $nsup->declare_prefixes($prefix1 => $uri1, $prefix2 => $uri2);

  # get a single prefix for a URI (randomly)

  $prefix = $nsup->get_prefix($uri);

  # get all prefixes for a URI (probably better)

  @prefixes = $nsup->get_prefixes($uri);

  # get all prefixes in scope

  @prefixes = $nsup->get_prefixes();

  # get all prefixes that were declared for the current scope

  @prefixes = $nsup->get_declared_prefixes;

  # get a URI for a given prefix

  $uri = $nsup->get_uri($prefix);

  # get info on a qname (java-ish way, it's a bit weird)

  ($ns_uri, $local_name, $qname) = $nsup->process_name($qname, $is_attr);

  # the same, more perlish

  ($ns_uri, $prefix, $local_name) = $nsup->process_element_name($qname);

  ($ns_uri, $prefix, $local_name) = $nsup->process_attribute_name($qname);

  # remove the current context

  $nsup->pop_context;

  # reset the object for reuse in another document

  $nsup->reset;

  # a simple helper to process Clarkian Notation

  my ($ns, $lname) = $nsup->parse_jclark_notation('{http://foo}bar');

  # or (given that it doesn't care about the object

  my ($ns, $lname) = XML::NamespaceSupport->parse_jclark_notation('{http://foo}bar');

=head1 DESCRIPTION

This module offers a simple to process namespaced XML names (unames)

from within any application that may need them. It also helps maintain

a prefix to namespace URI map, and provides a number of basic checks.

The model for this module is SAX2's NamespaceSupport class, readable at

http://www.megginson.com/SAX/Java/javadoc/org/xml/sax/helpers/NamespaceSupport.html.

It adds a few perlisations where we thought it appropriate.

=head1 METHODS

=over 4

=item * XML::NamespaceSupport->new(\%options)

A simple constructor.

The options are C<xmlns>, C<fatal_errors>, and C<auto_prefix>

If C<xmlns> is turned on (it is off by default) the mapping from the

xmlns prefix to the URI defined for it in DOM level 2 is added to the

list of predefined mappings (which normally only contains the xml

prefix mapping).

If C<fatal_errors> is turned off (it is on by default) a number of

validity errors will simply be flagged as failures, instead of

die()ing.

If C<auto_prefix> is turned on (it is off by default) when one

provides a prefix of C<undef> to C<declare_prefix> it will generate a

random prefix mapped to that namespace. Otherwise an undef prefix will

trigger a warning (you should probably know what you're doing if you

turn this option on).

=item * $nsup->push_context

Adds a new empty context to the stack. You can then populate it with

new prefixes defined at this level.

=item * $nsup->pop_context

Removes the topmost context in the stack and reverts to the previous

one. It will die() if you try to pop more than you have pushed.

=item * $nsup->declare_prefix($prefix, $uri)

Declares a mapping of $prefix to $uri, at the current level.

Note that with C<auto_prefix> turned on, if you declare a prefix

mapping in which $prefix is undef(), you will get an automatic prefix

selected for you. If it is off you will get a warning.

This is useful when you deal with code that hasn't kept prefixes around

and need to reserialize the nodes. It also means that if you want to

set the default namespace (ie with an empty prefix) you must use the

empty string instead of undef. This behaviour is consistent with the

SAX 2.0 specification.

=item * $nsup->declare_prefixes(%prefixes2uris)

Declares a mapping of several prefixes to URIs, at the current level.

=item * $nsup->get_prefix($uri)

Returns a prefix given an URI. Note that as several prefixes may be

mapped to the same URI, it returns an arbitrary one. It'll return

undef on failure.

=item * $nsup->get_prefixes($uri)

Returns an array of prefixes given an URI. It'll return all the

prefixes if the uri is undef.

=item * $nsup->get_declared_prefixes

Returns an array of all the prefixes that have been declared within

this context, ie those that were declared on the last element, not

those that were declared above and are simply in scope.

=item * $nsup->get_uri($prefix)

Returns a URI for a given prefix. Returns undef on failure.

=item * $nsup->process_name($qname, $is_attr)

Given a qualified name and a boolean indicating whether this is an

attribute or another type of name (those are differently affected by

default namespaces), it returns a namespace URI, local name, qualified

name tuple. I know that that is a rather abnormal list to return, but

it is so for compatibility with the Java spec. See below for more

Perlish alternatives.

If the prefix is not declared, or if the name is not valid, it'll

either die or return undef depending on the current setting of

C<fatal_errors>.

=item * $nsup->undeclare_prefix($prefix);

Removes a namespace prefix from the current context. This function may

be used in SAX's end_prefix_mapping when there is fear that a namespace 

declaration might be available outside their scope (which shouldn't 

normally happen, but you never know ;). This may be needed in order to

properly support Namespace 1.1.

=item * $nsup->process_element_name($qname)

Given a qualified name, it returns a namespace URI, prefix, and local

name tuple. This method applies to element names.

If the prefix is not declared, or if the name is not valid, it'll

either die or return undef depending on the current setting of

C<fatal_errors>.

=item * $nsup->process_attribute_name($qname)

Given a qualified name, it returns a namespace URI, prefix, and local

name tuple. This method applies to attribute names.

If the prefix is not declared, or if the name is not valid, it'll

either die or return undef depending on the current setting of

C<fatal_errors>.

=item * $nsup->reset

Resets the object so that it can be reused on another document.

=back

All methods of the interface have an alias that is the name used in

the original Java specification. You can use either name

interchangeably. Here is the mapping:

  Java name                 Perl name

  ---------------------------------------------------

  pushContext               push_context

  popContext                pop_context

  declarePrefix             declare_prefix

  declarePrefixes           declare_prefixes

  getPrefix                 get_prefix

  getPrefixes               get_prefixes

  getDeclaredPrefixes       get_declared_prefixes

  getURI                    get_uri

  processName               process_name

  processElementName        process_element_name

  processAttributeName      process_attribute_name

  parseJClarkNotation       parse_jclark_notation

  undeclarePrefix           undeclare_prefix

=head1 VARIABLES

Two global variables are made available to you. They used to be constants but

simple scalars are easier to use in a number of contexts. They are not

exported but can easily be accessed from any package, or copied into it.