NAME
    Geo::UK::Postcode::Regex - regular expressions for handling British
    postcodes

VERSION
    version 0.001

SYNOPSIS
        use Geo::UK::Postcode::Regex;
    
        ## REGULAR EXPRESSIONS
    
        my $lax_re    = Geo::UK::Postcode::Regex->regex;
        my $strict_re = Geo::UK::Postcode::Regex->regex_strict;
        my $valid_re  = Geo::UK::Postcode::Regex->valid_regex;
    
        if ( $foo =~ $lax_re ) {
            my ( $area, $district, $sector, $unit ) = ( $1, $2, $3, $4 );
            my $subdistrict = $district =~ s/([A-Z])$// ? $1 : undef;
            ...
        }
    
        if ( $foo =~ $strict_re ) {
            my ( $area, $district, $sector, $unit ) = ( $1, $2, $3, $4 );
            my $subdistrict = $district =~ s/([A-Z])$// ? $1 : undef;
            ...
        }
    
        if ( $foo =~ $valid_re ) {
            my ( $outcode, $sector, $unit ) = ( $1, $2, $3 );
            ...
        }

        # VALIDATION METHODS
        use Geo::UK::Postcode::Regex qw/ is_valid_pc is_strict_pc is_lax_pc /;
    
        if (is_valid_pc("GE0 1UK")) {
            ...
        }
        if (is_strict_pc("GE0 1UK")) {
            ...
        }
        if (is_lax_pc("GE0 1UK")) {
            ...
        }
    
        ## PARSING
        my $parsed = Geo::UK::Postcode::Regex->parse("WC1H 9EB");
    
        # returns:
        # {   area             => 'WC',
        #     district         => '1',
        #     subdistrict      => 'H',
        #     sector           => '9',
        #     unit             => 'EB',
        #     outcode          => 'WC1H',
        #     incode           => '9EB',
        #     valid_outcode    => 1 | 0,
        #     strict           => 1 | 0,
        #     partial          => 1 | 0,
        #     non_geographical => 1 | 0,
        #     bfpo             => 1 | 0,
        # }
    
        # strict parsing (only valid characters):
        ...->parse( $pc, { strict => 1 } )
    
        # valid outcodes only
        ...->parse( $pc, { valid => 1 } )
    
        # match partial postcodes, e.g. 'WC1H', 'WC1H 9'
        ...->parse( $pc, { partial => 1 } )
    
    
        ## EXTRACT OUTCODE
        my $outcode = Geo::UK::Postcode::Regex->outcode("AB101AA"); # returns 'AB10'
    
        my $outcode = Geo::UK::Postcode::Regex->outcode( $postcode, { valid => 1 } )
            or die "Invalid postcode";
    
    
        ## POSTTOWNS
        my (@posttowns) = Geo::UK::Postcode::Regex->outcode_to_posttowns($outcode);
    
    
        ## OUTCODES
        my (@outcodes) = Geo::UK::Postcode::Regex->posttown_to_outcodes($posttown);

DESCRIPTION
    Parsing UK postcodes with regular expressions. This package has been
    separated from Geo::UK::Postcode so it can be installed and used without
    dependencies.

    Can handle partial postcodes (just the outcode or sector) and can test
    against valid characters and currently valid outcodes.

    Also can determine the posttown(s) from a postcode.

    Districts and post town information taken from:
    <https://en.wikipedia.org/wiki/Postcode_districts>

NOTES AND LIMITATIONS
    When parsing a partial postcode, whitespace may be required to separate
    the outcode from the sector.

    For example the sector 'B1 1' cannot be distinguished from the district
    'B11' without whitespace.

METHODS
  strict_regex, regex, valid_regex
    Return regular expressions to parse postcodes and capture the
    constituent parts: area, district, sector and unit (or outcode, sector
    and unit in the case of "valid_regex").

    "strict_regex" checks that the postcode only contains valid characters
    according to the postcode specifications.

    "valid_regex" checks that the outcode currently exists.

  strict_regex_partial, regex_partial, valid_regex_partial
    As above, but matches on partial postcodes of just the outcode or sector

  is_valid_pc, is_strict_pc, is_lax_pc
        if (is_valid_pc( "AB1 2CD" ) ) { ... }

    Alternative way to access the regexes.

  parse
        my $parsed = Geo::UK::Postcode::Regex->parse( $pc, \%opts );

    Returns hashref of the constituent parts.

    Options:

    strict
        Returns false if string contains invalid characters (e.g. a Q as
        first letter)

    valid
        Returns false if string is not a currently existing outcode.

    partial
        Allows partial postcodes to be matched. In practice this means
        either an outcode ( area and district ) or an outcode together with
        the sector .

  outcode
        my $outcode = Geo::UK::Postcode::Regex->outcode( $pc, \%opts );

    Extract the outcode (area and district) from a postcode string. Will
    work on full or partial postcodes.

    Second argument is a hashref of options - see "parse()"

  outcode_to_posttowns
        my ( $posttown1, $posttown2, ... )
            = Geo::UK::Postcode::Regex->outcode_to_posttowns($outcode);

    Returns posttown(s) for supplied outcode.

    Note - most outcodes will only have one posttown, but some are shared
    between two posttowns.

  posttown_to_outcodes
        my @outcodes = Geo::UK::Postcode::Regex->posttown_to_outcodes($posttown);

    Returns the outcodes covered by a posttown. Note some outcodes are
    shared between posttowns.

  outcodes_lookup
        my %outcodes = %{ Geo::UK::Postcodes::Regex->outcodes_lookup };
        print "valid outcode" if $outcodes{$outcode};
        my @posttowns = @{ $outcodes{$outcode} };

    Hashref of outcodes to posttown(s);

  posttowns_lookup
        my %posttowns = %{ Geo::UK::Postcodes::Regex->posttowns_lookup };
        print "valid posttown" if $posttowns{$posttown};
        my @outcodes = @{ $[posttowns{$posttown} };

    Hashref of posttown to outcode(s);

SUPPORT
  Bugs / Feature Requests
    Please report any bugs or feature requests through the issue tracker at
    <https://github.com/mjemmeson/Geo-UK-Postcode-Regex/issues>. You will be
    notified automatically of any progress on your issue.

  Source Code
    This is open source software. The code repository is available for
    public review and contribution under the terms of the license.

    <https://github.com/mjemmeson/Geo-UK-Postcode-Regex>

      git clone https://github.com/mjemmeson/Geo-UK-Postcode-Regex.git

AUTHOR
    Michael Jemmeson <mjemmeson@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2013 by Michael Jemmeson.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.