lib.php

<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

function decode_html_entities($xml) {
    $htmlentitiestable = get_html_translation_table(HTML_ENTITIES, ENT_QUOTES, 'UTF-8');
    $xmlentitiestable = get_html_translation_table(HTML_SPECIALCHARS , ENT_COMPAT, 'UTF-8');
    $entitiestable = array_diff($htmlentitiestable, $xmlentitiestable);
    $decodetable = array_flip($entitiestable);
    $xml = str_replace(array_keys($decodetable), array_values($decodetable), $xml);
    return $xml;
}

function wrsqz_mathml_decode($input) {
    // @codingStandardsIgnoreLine
    $from = array('«', '»', '¨', '§', '`');
    $to = array('<', '>', '"', '&', '\'');
    $r = str_replace($from, $to, $input);
    return decode_html_entities($r);
}