Lingua_Stem_Ru

<?php


/**
 * Class Lingua_Stem_Ru
 * Стеммер Портера.
 * взято от сюда: http://forum.dklab.ru/php/advises/HeuristicWithoutTheDictionaryExtractionOfARootFromRussianWord.html
 */
class Lingua_Stem_Ru
{
    var $VERSION = "0.02";
    var $Stem_Caching = 0;
    var $Stem_Cache = array();
    var $VOWEL = '/аеиоуыэюя/ui';
    var $PERFECTIVEGROUND = '/((ив|ивши|ившись|ыв|ывши|ывшись)|((?<=[ая])(в|вши|вшись)))$/ui';
    var $REFLEXIVE = '/(с[яь])$/ui';
    var $ADJECTIVE = '/(ее|ие|ые|ое|ими|ыми|ей|ий|ый|ой|ем|им|ым|ом|его|ого|еых|ую|юю|ая|яя|ою|ею)$/ui';
    var $PARTICIPLE = '/((ивш|ывш|ующ)|((?<=[ая])(ем|нн|вш|ющ|щ)))$/ui';
    var $VERB = '/((ила|ыла|ена|ейте|уйте|ите|или|ыли|ей|уй|ил|ыл|им|ым|ены|ить|ыть|ишь|ую|ю)|((?<=[ая])(ла|на|ете|йте|ли|й|л|ем|н|ло|но|ет|ют|ны|ть|ешь|нно)))$/ui';
    var $NOUN = '/(а|ев|ов|ие|ье|е|иями|ями|ами|еи|ии|и|ией|ей|ой|ий|й|и|ы|ь|ию|ью|ю|ия|ья|я)$/ui';
    var $RVRE = '/^(.*?[аеиоуыэюя])(.*)$/ui';
    var $DERIVATIONAL = '/[^аеиоуыэюя][аеиоуыэюя]+[^аеиоуыэюя]+[аеиоуыэюя].*(?<=о)сть?$/ui';

    function s(&$s, $re, $to)
    {
        $orig = $s;
        $s = preg_replace($re, $to, $s);

        return $orig !== $s;
    }

    function m($s, $re)
    {
        return preg_match($re, $s);
    }

    function stem_word($word)
    {
        //$word = strtolower($word);
        $word = strtr($word, array('ё' => 'е'));
        # Check against cache of stemmed words
        if ($this->Stem_Caching && isset($this->Stem_Cache[$word]))
        {
            return $this->Stem_Cache[$word];
        }
        $stem = $word;
        do
        {
            if (!preg_match($this->RVRE, $word, $p)) break;
            $start = $p[1];
            $RV = $p[2];
            if (!$RV) break;

            # Step 1
            if (!$this->s($RV, $this->PERFECTIVEGROUND, ''))
            {
                $this->s($RV, $this->REFLEXIVE, '');

                if ($this->s($RV, $this->ADJECTIVE, ''))
                {
                    $this->s($RV, $this->PARTICIPLE, '');
                }
                else
                {
                    if (!$this->s($RV, $this->VERB, '')) $this->s($RV, $this->NOUN, '');
                }
            }

            # Step 2
            $this->s($RV, '/и$/ui', '');

            # Step 3
            if ($this->m($RV, $this->DERIVATIONAL)) $this->s($RV, '/ость?$/ui', '');

            # Step 4
            if (!$this->s($RV, '/ь$/ui', ''))
            {
                $this->s($RV, '/ейше?/ui', '');
                $this->s($RV, '/нн$/ui', 'н');
            }

            $stem = $start . $RV;
        } while (false);
        if ($this->Stem_Caching) $this->Stem_Cache[$word] = $stem;

        return $stem;
    }

    function stem_caching($parm_ref)
    {
        $caching_level = @$parm_ref['-level'];
        if ($caching_level)
        {
            if (!$this->m($caching_level, '/^[012]$/'))
            {
                die(__CLASS__ . "::stem_caching() - Legal values are '0','1' or '2'. '$caching_level' is not a legal value");
            }
            $this->Stem_Caching = $caching_level;
        }

        return $this->Stem_Caching;
    }

    function clear_stem_cache()
    {
        $this->Stem_Cache = array();
    }
}