143 lines
4.0 KiB
PHP
143 lines
4.0 KiB
PHP
<?php
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/**
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* Generate regular expressions to match a list of zip codes
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*
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* Copyright (C) 2014-2023 Ryan Specialty, LLC.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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function gen_re_quick( $data )
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{
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$re = ( '^' . gen_re( $data, 0 ) );
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// attempt to simplify the regex (we're not going to put a lot of effort into
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// this)
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return re_simplify( $re );
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}
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function gen_re( $data, $offset )
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{
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// if we've reached the end of the zip length, or if there's no more zips to
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// look at, then stop
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if ( ( count( $data ) === 0 )
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|| ( $offset === 5 )
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)
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{
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return '';
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}
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$out = '(';
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// loop through each digit at the current offset
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$last = '';
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foreach ( $data as $zip )
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{
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if ( !( isset( $zip[ $offset ] ) ) )
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{
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continue;
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}
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$digit = $zip[ $offset ];
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// if we've already seen this digit in the current position, then
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// continue
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if ( $digit === $last )
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{
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continue;
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}
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// we're going to recurse now, delimiting allowable digits with pipes
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// (for 'OR'); we'll recurse on a sublist that matches the zip up to
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// (and including) the current digit (to do this, note that we only need
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// to check the current digit, since our current list is already a
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// sublist of the parent list up to the current point)
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$prefix = substr( $zip, 0, $offset + 1 );
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$out .= ( $last === '' ) ? '' : '|';
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$out .= $digit . gen_re(
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filter_data( $data, $digit, $offset ),
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( $offset + 1 )
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);
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$last = $digit;
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}
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return $out . ')';
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}
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function filter_data( $data, $chr, $offset )
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{
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$ret = array();
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foreach ( $data as $val )
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{
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if ( $val[ $offset] === $chr )
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{
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$ret[] = $val;
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}
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}
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return $ret;
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}
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function re_simplify( $re )
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{
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// the only simplification we currently do is joining sequential digit ORs
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// into a character range (e.g. (1|2|3|4) becomes [1-4])
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return preg_replace_callback( '/\([0-9](\|[0-9])*\)/', function( $results )
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{
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$match = $results[ 0 ];
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$digits = explode( '|', str_replace( array( '(', ')' ), '', $match ) );
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// are the digits sequential (we will only perform this optimization if
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// there's more than 3 digits, since otherwise the replacement would
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// result in a string of equal or greater length)?
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if ( ( count( $digits ) > 3 ) && is_seq( $digits ) )
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{
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return sprintf( '[%d-%d]',
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$digits[ 0 ],
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$digits[ count( $digits ) - 1 ]
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);
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}
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elseif ( count( $digits ) === 1 )
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{
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// if there's only one digit, then that's all we need to return
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return $digits[ 0 ];
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}
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return '[' . implode( '', $digits ) . ']';
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}, $re );
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}
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function is_seq( $digits, $last = '' )
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{
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// stop recursing once we're out of digits
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if ( count( $digits ) === 0 )
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{
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return true;
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}
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// grab the current digit and remove it from the list (this has the effect
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// of both cons and cdr)
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$digit = (int)( array_shift( $digits ) );
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// consider this a sequence if this digit is one more than the last (or if
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// there is no last digit) and if the following digit is sequential
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return ( ( $last === '' ) || ( $digit === ( $last + 1) ) )
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&& is_seq( $digits, $digit );
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}
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