mirror of
https://github.com/osm-search/Nominatim.git
synced 2024-09-11 19:17:17 +03:00
145 lines
4.4 KiB
PHP
145 lines
4.4 KiB
PHP
<?php
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/**
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* SPDX-License-Identifier: GPL-2.0-only
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*
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* This file is part of Nominatim. (https://nominatim.org)
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*
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* Copyright (C) 2022 by the Nominatim developer community.
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* For a full list of authors see the git log.
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*/
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namespace Nominatim;
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/**
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* A word list creator based on simple splitting by space.
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*
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* Creates possible permutations of split phrases by finding all combination
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* of splitting the phrase on space boundaries.
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*/
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class SimpleWordList
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{
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const MAX_WORDSET_LEN = 20;
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const MAX_WORDSETS = 100;
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// The phrase as a list of simple terms (without spaces).
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private $aWords;
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/**
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* Create a new word list
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*
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* @param string sPhrase Phrase to create the word list from. The phrase is
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* expected to be normalised, so that there are no
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* subsequent spaces.
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*/
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public function __construct($sPhrase)
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{
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if (strlen($sPhrase) > 0) {
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$this->aWords = explode(' ', $sPhrase);
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} else {
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$this->aWords = array();
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}
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}
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/**
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* Get all possible tokens that are present in this word list.
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*
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* @return array The list of string tokens in the word list.
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*/
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public function getTokens()
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{
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$aTokens = array();
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$iNumWords = count($this->aWords);
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for ($i = 0; $i < $iNumWords; $i++) {
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$sPhrase = $this->aWords[$i];
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$aTokens[$sPhrase] = $sPhrase;
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for ($j = $i + 1; $j < $iNumWords; $j++) {
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$sPhrase .= ' '.$this->aWords[$j];
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$aTokens[$sPhrase] = $sPhrase;
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}
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}
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return $aTokens;
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}
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/**
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* Compute all possible permutations of phrase splits that result in
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* words which are in the token list.
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*/
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public function getWordSets($oTokens)
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{
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$iNumWords = count($this->aWords);
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if ($iNumWords == 0) {
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return null;
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}
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// Caches the word set for the partial phrase up to word i.
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$aSetCache = array_fill(0, $iNumWords, array());
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// Initialise first element of cache. There can only be the word.
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if ($oTokens->containsAny($this->aWords[0])) {
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$aSetCache[0][] = array($this->aWords[0]);
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}
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// Now do the next elements using what we already have.
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for ($i = 1; $i < $iNumWords; $i++) {
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for ($j = $i; $j > 0; $j--) {
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$sPartial = $j == $i ? $this->aWords[$j] : $this->aWords[$j].' '.$sPartial;
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if (!empty($aSetCache[$j - 1]) && $oTokens->containsAny($sPartial)) {
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$aPartial = array($sPartial);
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foreach ($aSetCache[$j - 1] as $aSet) {
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if (count($aSet) < SimpleWordList::MAX_WORDSET_LEN) {
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$aSetCache[$i][] = array_merge($aSet, $aPartial);
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}
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}
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if (count($aSetCache[$i]) > 2 * SimpleWordList::MAX_WORDSETS) {
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usort(
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$aSetCache[$i],
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array('\Nominatim\SimpleWordList', 'cmpByArraylen')
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);
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$aSetCache[$i] = array_slice(
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$aSetCache[$i],
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0,
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SimpleWordList::MAX_WORDSETS
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);
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}
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}
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}
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// finally the current full phrase
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$sPartial = $this->aWords[0].' '.$sPartial;
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if ($oTokens->containsAny($sPartial)) {
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$aSetCache[$i][] = array($sPartial);
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}
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}
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$aWordSets = $aSetCache[$iNumWords - 1];
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usort($aWordSets, array('\Nominatim\SimpleWordList', 'cmpByArraylen'));
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return array_slice($aWordSets, 0, SimpleWordList::MAX_WORDSETS);
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}
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/**
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* Custom search routine which takes two arrays. The array with the fewest
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* items wins. If same number of items then the one with the longest first
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* element wins.
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*/
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public static function cmpByArraylen($aA, $aB)
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{
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$iALen = count($aA);
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$iBLen = count($aB);
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if ($iALen == $iBLen) {
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return strlen($aB[0]) <=> strlen($aA[0]);
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}
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return ($iALen < $iBLen) ? -1 : 1;
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}
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public function debugInfo()
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{
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return $this->aWords;
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}
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}
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