use 5.006; use strict; use warnings;
package Parse::MIME;
our $VERSION = '1.005';
use Exporter ();
our @ISA = 'Exporter';
our @EXPORT_OK = qw(
&parse_mime_type &parse_media_range &parse_media_range_list
&fitness_and_quality_parsed &quality_parsed &quality
&best_match
);
our %EXPORT_TAGS = ( all => \@EXPORT_OK );
sub _numify($) { no warnings 'numeric'; 0 + shift }
# takes any number of args and returns copies stripped of surrounding whitespace
sub _strip { s/\A +//, s/ +\z// for my @s = @_; @s[ 0 .. $#s ] }
# check whether first two args are equal or one of them is a wildcard
sub _match { $_[0] eq $_[1] or grep { $_ eq '*' } @_[0,1] }
sub parse_mime_type {
my ( $mime_type ) = @_;
my @part = split /;/, $mime_type;
my $full_type = _strip shift @part;
my %param = map { _strip split /=/, $_, 2 } @part;
# Java URLConnection class sends an Accept header that includes a single "*"
# Turn it into a legal wildcard.
$full_type = '*/*' if $full_type eq '*';
my ( $type, $subtype ) = _strip split m!/!, $full_type;
return ( $type, $subtype, \%param );
}
sub parse_media_range {
my ( $range ) = @_;
my ( $type, $subtype, $param ) = parse_mime_type $range;
$param->{'q'} = 1
unless defined $param->{'q'}
and length $param->{'q'}
and _numify $param->{'q'} <= 1
and _numify $param->{'q'} >= 0;
return ( $type, $subtype, $param );
}
sub parse_media_range_list {
my ( $media_range_list ) = @_;
return map { parse_media_range $_ } split /,/, $media_range_list;
}
sub fitness_and_quality_parsed {
my ( $mime_type, @parsed_ranges ) = @_;
my ( $best_fitness, $best_fit_q ) = ( -1, 0 );
my ( $target_type, $target_subtype, $target_param )
= parse_media_range $mime_type;
while ( my ( $type, $subtype, $param ) = splice @parsed_ranges, 0, 3 ) {
if ( _match( $type, $target_type ) and _match( $subtype, $target_subtype ) ) {
my $fitness
= ( $type eq $target_type ? 100 : 0 )
+ ( $subtype eq $target_subtype ? 10 : 0 )
;
while ( my ( $k, $v ) = each %$param ) {
++$fitness
if $k ne 'q'
and exists $target_param->{ $k }
and $target_param->{ $k } eq $v;
}
( $best_fitness, $best_fit_q ) = ( $fitness, $param->{'q'} )
if $fitness > $best_fitness;
}
}
return ( $best_fitness, _numify $best_fit_q );
}
sub quality_parsed {
return +( fitness_and_quality_parsed @_ )[1];
}
sub quality {
my ( $mime_type, $ranges ) = @_;
my @parsed_range = parse_media_range_list $ranges;
return quality_parsed $mime_type, @parsed_range;
}
sub best_match {
my ( $supported, $header ) = @_;
my @parsed_header = parse_media_range_list $header;
# fitness_and_quality_parsed will return fitness -1 on failure,
# so we want to start with an invalid value greater than that
my ( $best_fitness, $best_fit_q, $match ) = ( -.5, 0 );
for my $type ( @$supported ) {
my ( $fitness, $fit_q ) = fitness_and_quality_parsed $type, @parsed_header;
next if $fitness < $best_fitness;
next if $fitness == $best_fitness and $fit_q < $best_fit_q;
( $best_fitness, $best_fit_q, $match ) = ( $fitness, $fit_q, $type );
}
return if not defined $match;
return $match;
}
__END__
=pod
=encoding UTF-8
=head1 NAME
Parse::MIME - Parse mime-types, match against media ranges
=head1 SYNOPSIS
use Parse::MIME qw( best_match );
print best_match( [ qw( application/xbel+xml text/xml ) ], 'text/*;q=0.5,*/*; q=0.1' );
# text/xml
=head1 DESCRIPTION
This module provides basic functions for handling mime-types. It can handle
matching mime-types against a list of media-ranges. See section 14.1 of the
HTTP specification [RFC 2616] for a complete explanation:
L<http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1>
=head1 INTERFACE
None of the following functions are exported by default. You can use the
C<:all> tag to import all of them into your package:
use Parse::MIME ':all';
=head2 parse_mime_type
Parses a mime-type into its component parts and returns type, subtype and
params, where params is a reference to a hash of all the parameters for the
media range:
parse_mime_type 'application/xhtml;q=0.5'
# ( 'application', 'xhtml', { q => 0.5 } )
=head2 parse_media_range
Media-ranges are mime-types with wild-cards and a C<q> quality parameter. This
function works just like L</parse_mime_type>, but also guarantees that there is
a value for C<q> in the params hash, supplying the default value if necessary.
parse_media_range 'application/xhtml'
# ( 'application', 'xhtml', { q => 1 } )
=head2 parse_media_range_list
Media-range lists are comma-separated lists of media ranges. This function
works just like L</parse_media_range>, but accepts a list of media ranges and
returns for all of media-ranges.
my @l = parse_media_range_list 'application/xhtml, text/html;q=0.7'
# ( 'application', 'xhtml', { q => 1 }, 'text', 'html', { q => 0.7 } )
=head2 fitness_and_quality_parsed
Find the best match for a given mime-type (passed as the first parameter)
against a list of media ranges that have already been parsed by
L</parse_media_range> (passed as a flat list). Returns the fitness value and
the value of the C<q> quality parameter of the best match, or C<( -1, 0 )> if
no match was found.
# for @l see above
fitness_and_quality_parsed( 'text/html', @l )
# ( 110, 0.7 )
=head2 quality
Determines the quality (C<q>) of a mime-type (passed as the first parameter)
when compared against a media-range list string. F.ex.:
quality( 'text/html', 'text/*;q=0.3, text/html;q=0.7, text/html;level=1, text/html;level=2;q=0.4, */*;q=0.5' )
# 0.7
=head2 quality_parsed
Just like L</quality>, except the second parameter must be pre-parsed by
L</parse_media_range_list>.
=head2 best_match
Choose the mime-type with the highest quality (C<q>) from a list of candidates.
Takes an array of supported mime-types as the first parameter and finds the
best match for all the media-ranges listed in header, which is passed as the
second parameter. The value of header must be a string that conforms to the
format of the HTTP C<Accept> header. F.ex.:
best_match( [ qw( application/xbel+xml text/xml ) ], 'text/*;q=0.5,*/*; q=0.1' )
# 'text/xml'
=head1 AUTHOR
Aristotle Pagaltzis <pagaltzis@gmx.de>
=head1 COPYRIGHT AND LICENSE
This software is copyright (c) 2018 by Aristotle Pagaltzis.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=cut