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

SYNOPSIS
    See Geo::UK::Postcode::Regex::Simple for an alternative interface.

        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;

        # matching only
        if ( $foo =~ $lax_re )    {...}
        if ( $foo =~ $strict_re ) {...}
        if ( $foo =~ $valid_re )  {...}

        # matching and using components - see also parse()
        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            => 1,
        #     strict           => 1,
        #     partial          => 0,
        #     non_geographical => 0,
        #     bfpo             => 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' - see below
        ...->parse( $pc, { partial => 1 } )


        ## PARSING PARTIAL POSTCODES

        # outcode (district) only
        my $parsed = Geo::UK::Postcode::Regex->parse( "AB10", { partial => 1 } );

        # returns:
        # {   area             => 'AB',
        #     district         => '10',
        #     subdistrict      => undef,
        #     sector           => undef,
        #     unit             => undef,
        #     outcode          => 'AB10',
        #     incode           => undef,
        #     valid            => 1,
        #     strict           => 1,
        #     partial          => 1,
        #     non_geographical => 0,
        #     bfpo             => 0,
        # }

        # sector only
        my $parsed = Geo::UK::Postcode::Regex->parse( "AB10 1", { partial => 1 } );

        # returns:
        # {   area             => 'AB',
        #     district         => '10',
        #     subdistrict      => undef,
        #     sector           => 1,
        #     unit             => undef,
        #     outcode          => 'AB10',
        #     incode           => '1',
        #     valid            => 1,
        #     strict           => 1,
        #     partial          => 1,
        #     non_geographical => 0,
        #     bfpo             => 0,
        # }


        ## EXTRACT OUTCODE FROM POSTCODE

        my $outcode = Geo::UK::Postcode::Regex->outcode("AB101AA"); # returns 'AB10'

        my $outcode = Geo::UK::Postcode::Regex->outcode( $postcode, { valid => 1 } )
            or die "Invalid postcode";


        ## EXTRACT POSTCODES FROM TEXT

        # \%options as per parse, excluding partial
        my @extracted = Geo::UK::Postcode::Regex->extract( $text, \%options );


        ## 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 with
    fewer 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>

IMPORTANT CHANGES FOR VERSION 0.014
    Please note that various bugfixes have changed the following:

    *   Unanchored regular expressions no longer match valid postcodes
        within invalid ones.

    *   Unanchored regular expressions in partial mode now can match a valid
        or strict outcode with an invalid incode.

    Please get in touch if you have any questions.

    See Geo::UK::Postcode::Regex::Simple for other changes affecting the
    Simple interface.

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. This is not a problem when parsing full
    postcodes.

VALIDATION METHODS
    The following methods are for validating postcodes to various degrees.

    Geo::UK::Postcode::Regex::Simple may provide a more convenient way of
    using and customising these.

  regex, strict_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.

  regex_partial, strict_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.

PARSING METHODS
    The following methods are for parsing postcodes or strings containing
    postcodes.

  PARSING_OPTIONS
    The parsing methods can take the following options, passed via a
    hashref:

    strict
        Postcodes must not contain invalid characters according to the
        postcode specification. For example a 'Q' may not appear as the
        first character.

    valid
        Postcodes must contain an outcode (area + district) that currently
        exists, in addition to conforming to the "strict" definition.

        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.

  extract
        my @extracted = Geo::UK::Postcode::Regex->extract( $string, \%options );

    Returns a list of full postcodes extracted from a string.

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

    Returns hashref of the constituent parts - see SYNOPSIS. Missing parts
    will be set as undefined.

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

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

LOOKUP METHODS
  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::Postcode::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::Postcode::Regex->posttowns_lookup };
        print "valid posttown" if $posttowns{$posttown};
        my @outcodes = @{ $[posttowns{$posttown} };

    Hashref of posttown to outcode(s);

SEE ALSO
    *   Geo::UK::Postcode

    *   Geo::Address::Mail::UK

    *   Geo::Postcode

    *   Data::Validation::Constraints::Postcode

    *   CGI::Untaint::uk_postcode

    *   Form::Validator::UKPostcode

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 git://github.com/mjemmeson/geo-uk-postcode-regex.git

AUTHOR
    Michael Jemmeson <mjemmeson@cpan.org>

COPYRIGHT
    Copyright 2015- Michael Jemmeson

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

