<?php

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

	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)
	{
		$word = mb_strtolower($word);
		$word = str_replace('ё', 'е', $word);
		# Check against cache of stemmed words
		if ($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$/', '');
			
			# Step 3
			if ($this->m($RV, $this->DERIVATIONAL))
			$this->s($RV, '/ость?$/', '');
			
			# Step 4
			if (!$this->s($RV, '/ь$/', '')) {
				$this->s($RV, '/ейше?/', '');
				$this->s($RV, '/нн$/', '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();
	}
}