package List::Breakdown; # Force me to write this properly use strict; use warnings; use utf8; # Target reasonably old Perls use 5.006; # Import required modules use Carp; # Handle exporting in a way Perl v5.6 should tolerate use base qw(Exporter); our @EXPORT_OK = 'breakdown'; # Specify package version our $VERSION = 0.07; # Dispatch table of functions to handle different ref types for the spec # hashref's values my %types = ( # If it's a hash, apply breakdown() again as if it were another root-level # spec HASH => sub { my $spec = shift; return { breakdown( $spec, @_ ) }; }, # If it's a subroutine, return a arrayref of all elements for which it # returns true CODE => sub { my $sub = shift; return [ grep { $sub->() } @_ ]; }, # If it's a regular expression, return an arrayref of all elements it # matches Regexp => sub { my $re = shift; return [ grep { $_ =~ $re } @_ ]; }, ); # Given a spec and a list of items, filter them into a hash of the same # structure sub breakdown { my ( $spec, @items ) = @_; # Check the spec is a hashref ref $spec eq 'HASH' or croak 'HASH reference expected for first argument'; # Start building a results hash my %results; for my $key ( keys %{$spec} ) { # Check that the value for this key is a reference my $ref = ref $spec->{$key} or croak "Reference expected for '$key'"; # Check it's a reference we understand exists $types{$ref} or croak "Unhandled ref type $ref for '$key'"; # Apply the appropriate subroutine for this reference type to the list # of items $results{$key} = $types{$ref}->( $spec->{$key}, @items ); } # Return the constructed result set return %results; } 1; __END__ =pod =for stopwords sublists Unhandled tradename licensable MERCHANTABILITY =head1 NAME List::Breakdown - Build list sublists matching conditions =head1 VERSION Version 0.07 =head1 DESCRIPTION This module "breaks down" a list--filtering elements from a list into a specified hash structure, which can be nested. It may be useful in situations where you have a big list of things to generate reports on or to otherwise filter into several sublists. It differs from the excellent C in the use of subroutine references for each category and in not requiring only one final category for any given item; an item can end up in the result set for more than one filter. You could maybe think of this as a multi-C that returns named results. =head1 SYNOPSIS my @words = qw(foo bar baz quux wibble florb); my $cats = { all => sub { 1 }, has_b => sub { m/ b /msx }, has_w => sub { m/ w /msx }, length => { 3 => sub { length == 3 }, 4 => sub { length == 4 }, long => sub { length > 4 }, }, has_ba => qr/ba/msx, }; my %filtered = breakdown $cats, @words; This puts the following structure in C<%filtered>: ( all => ['foo', 'bar', 'baz', 'quux', 'wibble', 'florb'], has_b => ['bar', 'baz', 'wibble', 'florb'], has_w => ['wibble'], length => { 3 => ['foo', 'bar', 'baz'], 4 => ['quux'], long => ['wibble', 'florb'], }, has_ba => ['bar', 'baz'], ) =head1 SUBROUTINES/METHODS =head2 B Given a hash reference structure and a list of items, apply each of the subroutines or regular expressions given as values of the hash reference, returning a new hash in the same structure with the tests replaced with the items for which the subroutine returns true, in the same way as C, or (as a shortcut) for which the regular expression matched. =head1 AUTHOR Tom Ryder C<< >> =head1 DIAGNOSTICS =over 4 =item HASH reference expected for first argument The first argument that B saw wasn't the hash reference it expects. That's the only format a spec is allowed to have. =item Reference expected for '%s' The value for the named key in the spec was not a reference, and one was expected. =item Unhandled ref type %s for '%s' The value for the named key in the spec is of a type that makes no sense to this module. Legal reference types are C, C, and C. =back =head1 DEPENDENCIES Perl 5.6 and the core modules C and C. =head1 CONFIGURATION AND ENVIRONMENT None required. =head1 INCOMPATIBILITIES None known. =head1 BUGS AND LIMITATIONS Definitely. This is a very early release. Please report any bugs or feature requests to C. =head1 SUPPORT You can find documentation for this module with the C command. perldoc List::Breakdown =head1 LICENSE AND COPYRIGHT Copyright (C) 2017 Tom Ryder This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at: Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license. If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license. This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder. This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed. Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. =cut