=head1 NAME

Web::URL::Checker - URL validator

=head1 SYNOPSIS

  use Web::URL::Checker;
  my $checker = Web::URL::Checker->new_from_string ($url);
  warn $checker->is_iri_reference;

=head1 METHODS

Following methods are available:

=over 4

=item $checker = Web::URL::Checker->new_from_string ($url)

Create a new checker from the specified URL.  The argument must be a
character string.

=item $code = $checker->onerror

=item $checker->onerror ($code)

Return or specify the code reference to which any errors and warnings
during the parsing is reported.

=back

=head2 Syntax testers

Following method returns whether the URL is syntactically conformant
or not.  There are versioned and unversioned methods.  In most cases,
only unversioned methods, which tests against the latest relevant
standard, should be used.

=over 4

=item $boolean = $checker->is_absolute_uri

=item $boolean = $checker->is_absolute_uri_3986

Return whether it is an absolute URI or not.  According to RFC 3986,
an absolute URI is an ASCII absolute URL without fragment identifier.
[RFC3986]

=item $boolean = $checker->is_empty_reference

Return whether it is a relative URL that is the empty string or not.

=item $boolean = $checker->is_iri

=item $boolean = $checker->is_iri_3987

Return whether it is an IRI or not.  According to RFC 3987, IRIs are a
subset of absolute URL with or without fragment identifier.  [RFC3987]

=item $boolean = $checker->is_iri_reference

=item $boolean = $checker->is_iri_reference_3987

Return whether it is an IRI reference or not.  According to RFC 3987,
IRI references are a subset of URL, absolute or relative, with or
without fragment identifier.  [RFC3987]

=item $boolean = $checker->is_relative_iri_reference

=item $boolean = $checker->is_relative_iri_reference_3987

Return whether is is a relative IRI reference or not.  According to
RFC 3987, relative IRI references are a subset of relative URL with or
without fragment identifier.  [RFC3987]

=item $boolean = $checker->is_relative_reference

=item $boolean = $checker->is_relative_reference_3986

Return whether it is a relative reference or not.  According to RFC
3986, a relative reference is an ASCII relative URL with or without
fragment identifier.  [RFC3986]

=item $boolean = $checker->is_uri

=item $boolean = $checker->is_uri_3986

Return whether it is a URI or not.  According to RFC 3986, a URI is an
ASCII absolute URL with or without fragment identifier.  [RFC3986]

=item $boolean = $checker->is_uri_reference

=item $boolean = $checker->is_uri_reference_3986

Return whether it is a URI reference or not.  According to RFC 3986, a
URI reference is an ASCII URL, absolute or relative, with or without
fragment identifier.  [RFC3986]

=back

=head2 Conformance checkers

Following methods check whether the URL is conforming or not.  Any
conformance error, as well as warnings, are reported through the
C<onerror> handler.  There are versioned and unversioned methods.  In
most cases, only unversioned methods, which tests against the latest
relevant standard, should be used.

=over 4

=item $checker->check_iri

=item $checker->check_iri_3987

Check whether it is a conforming IRI or not.  [RFC3987]

XXX This method is incomplete.

=item $checker->check_iri_reference

=item $checker->check_iri_reference_3987

Check whether it is a conforming IRI reference or not.  [RFC3987]

XXX This method is incomplete.

=item $checker->check_rdf_uri_reference

Check whether it is a conforming RDF URI reference or not.  [RDF]

XXX This method is incomplete.

=back

=head1 BUGS

The module does not support the URL Standard yet.

=head1 SPECIFICATIONS

=over 4

=item RDF

Resource Description Framework (RDF): Concepts and Abstract Syntax
<http://www.w3.org/TR/2004/REC-rdf-concepts-20040210/#section-Graph-URIref>.

=item RFC3986

Uniform Resource Identifier (URI): Generic Syntax
<http://tools.ietf.org/html/rfc3986>.

=item RFC3987

Internationalized Resource Identifiers (IRIs)
<http://tools.ietf.org/html/rfc3987>.

=back

=head1 HISTORY

This module derived from L<Message::URI::URIReference>
<https://github.com/wakaba/manakai/blob/master/lib/Message/URI/URIReference.pm>
and L<Whatpm::URIChecker>
<https://github.com/wakaba/manakai/blob/master/lib/Whatpm/URIChecker.pm>,
the former derived from
<https://github.com/wakaba/manakai/blob/master/lib/Message/URI/Generic.dis>.

=head1 AUTHOR

Wakaba <wakaba@suikawiki.org>.

=head1 LICENSE

Copyright 2006-2013 Wakaba <wakaba@suikawiki.org>.

This library is free software; you can redistribute it and/or modify
it under the same terms as Perl itself.

Portions of this module are derived from the example parser (April 7,
2004) available at
<http://www.gbiv.com/protocols/uri/rev-2002/uri_test.pl> that is
placed in the Public Domain by Roy T. Fielding and Day Software, Inc.

=back