Solr boost on field via entered query

BoostQueryModifier.php

<?php
 /***************************************************************
 *  Copyright notice
 *
 *  (c) 2015 Hans Höchtl <jhoechtl@gmail.com>
 *  All rights reserved
 *
 *  This script is part of the TYPO3 project. The TYPO3 project is
 *  free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  The GNU General Public License can be found at
 *  http://www.gnu.org/copyleft/gpl.html.
 *  A copy is found in the textfile GPL.txt and important notices to the license
 *  from the author is found in LICENSE.txt distributed with these scripts.
 *
 *
 *  This script is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  This copyright notice MUST APPEAR in all copies of the script!
 ***************************************************************/

namespace Onedrop\Solution\QueryModifier;


class BoostQueryModifier implements \Tx_Solr_QueryModifier {

	/**
	 * @var \Tx_Solr_Search
	 */
	protected $search;

	/**
	 * @param \Tx_Solr_Query $query
	 * @return \Tx_Solr_Query The modified query
	 */
	public function modifyQuery(\Tx_Solr_Query $query) {
		$queryString = $query->getQueryString();
		$boostQueries = $query->getQueryParameter('bq');
		$queryStringParts = explode(' ', $queryString);
		foreach ($queryStringParts as $queryStringPart) {
			$boostQueries[] = '(category_textM:' . $this->escape($queryStringPart) . ')^10';
		}
		$query->setBoostQuery($boostQueries);
		return $query;
	}


	/**
	 * Quote and escape search strings
	 *
	 * @param string $string String to escape
	 * @return string The escaped/quoted string
	 */
	public function escape($string) {
		if (!is_numeric($string)) {
			if (preg_match('/\W/', $string) == 1) {
				// multiple words

				$stringLength = strlen($string);
				if ($string{0} == '"' && $string{$stringLength - 1} == '"') {
					// phrase
					$string = trim($string, '"');
					$string = $this->escapePhrase($string);
				} else {
					$string = $this->escapeSpecialCharacters($string);
				}
			} else {
				$string = $this->escapeSpecialCharacters($string);
			}
		}

		return $string;
	}

	/**
	 * Escapes characters with special meanings in Lucene query syntax.
	 *
	 * @param string $value Unescaped - "dirty" - string
	 * @return string Escaped - "clean" - string
	 */
	protected function escapeSpecialCharacters($value) {
		// list taken from http://lucene.apache.org/core/4_4_0/queryparser/org/apache/lucene/queryparser/classic/package-summary.html#package_description
		// which mentions: + - && || ! ( ) { } [ ] ^ " ~ * ? : \ /
		// of which we escape: ( ) { } [ ] ^ " ~ : \ /
		// and explicitly don't escape: + - && || ! * ?
		$pattern = '/(\\(|\\)|\\{|\\}|\\[|\\]|\\^|"|~|\:|\\\\|\\/)/';
		$replace = '\\\$1';

		return preg_replace($pattern, $replace, $value);
	}

	/**
	 * Escapes a value meant to be contained in a phrase with characters with
	 * special meanings in Lucene query syntax.
	 *
	 * @param string $value Unescaped - "dirty" - string
	 * @return string Escaped - "clean" - string
	 */
	protected function escapePhrase($value) {
		$pattern = '/("|\\\)/';
		$replace = '\\\$1';

		return '"' . preg_replace($pattern, $replace, $value) . '"';
	}
}

ext_localconf.php

$GLOBALS['TYPO3_CONF_VARS']['EXTCONF']['solr']['modifySearchQuery']['categoryNameBoosting'] = 'Onedrop\\Solution\\QueryModifier\\BoostQueryModifier';