Proyectos de Subversion Moodle

<?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/>.

/**

 * Standard string manager.

 *

 * @package    core

 * @copyright  2010 Petr Skoda {@link http://skodak.org}

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

/**

 * Standard string_manager implementation

 *

 * Implements string_manager with getting and printing localised strings

 *

 * @package    core

 * @copyright  2010 Petr Skoda {@link http://skodak.org}

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class core_string_manager_standard implements core_string_manager {

    /** @var string location of all packs except 'en' */

    protected $otherroot;

    /** @var string location of all lang pack local modifications */

    protected $localroot;

    /** @var cache lang string cache - it will be optimised more later */

    protected $cache;

    /** @var int get_string() counter */

    protected $countgetstring = 0;

    /** @var array use disk cache */

    protected $translist;

    /** @var array language aliases to use in the language selector */

    protected $transaliases = [];

    /** @var cache stores list of available translations */

    protected $menucache;

    /** @var array list of cached deprecated strings */

    protected $cacheddeprecated;

    /**

     * Create new instance of string manager

     *

     * @param string $otherroot location of downloaded lang packs - usually $CFG->dataroot/lang

     * @param string $localroot usually the same as $otherroot

     * @param array $translist limit list of visible translations

     * @param array $transaliases aliases to use for the languages in the language selector

     */

    public function __construct($otherroot, $localroot, $translist, $transaliases = []) {

        $this->otherroot    = $otherroot;

        $this->localroot    = $localroot;

        if ($translist) {

            $this->translist = array_combine($translist, $translist);

            $this->transaliases = $transaliases;

        } else {

            $this->translist = array();

        }

        if ($this->get_revision() > 0) {

            // We can use a proper cache, establish the cache using the 'String cache' definition.

            $this->cache = cache::make('core', 'string');

            $this->menucache = cache::make('core', 'langmenu');

        } else {

            // We only want a cache for the length of the request, create a static cache.

            $options = array(

                'simplekeys' => true,

                'simpledata' => true

            );

            $this->cache = cache::make_from_params(cache_store::MODE_REQUEST, 'core', 'string', array(), $options);

            $this->menucache = cache::make_from_params(cache_store::MODE_REQUEST, 'core', 'langmenu', array(), $options);

        }

    }

    /**

     * Returns list of all explicit parent languages for the given language.

     *

     * English (en) is considered as the top implicit parent of all language packs

     * and is not included in the returned list. The language itself is appended to the

     * end of the list. The method is aware of circular dependency risk.

     *

     * @see self::populate_parent_languages()

     * @param string $lang the code of the language

     * @return array all explicit parent languages with the lang itself appended

     */

    public function get_language_dependencies($lang) {

        return $this->populate_parent_languages($lang);

    }

    /**

     * Load all strings for one component

     *

     * @param string $component The module the string is associated with

     * @param string $lang

     * @param bool $disablecache Do not use caches, force fetching the strings from sources

     * @param bool $disablelocal Do not use customized strings in xx_local language packs

     * @return array of all string for given component and lang

     */

    public function load_component_strings($component, $lang, $disablecache = false, $disablelocal = false) {

        global $CFG;

        list($plugintype, $pluginname) = core_component::normalize_component($component);

        if ($plugintype === 'core' and is_null($pluginname)) {

            $component = 'core';

        } else {

            $component = $plugintype . '_' . $pluginname;

        }

        $cachekey = $lang.'_'.$component.'_'.$this->get_key_suffix();

        $cachedstring = $this->cache->get($cachekey);

        if (!$disablecache and !$disablelocal) {

            if ($cachedstring !== false) {

                return $cachedstring;

            }

        }

        // No cache found - let us merge all possible sources of the strings.

        if ($plugintype === 'core') {

            $file = $pluginname;

            if ($file === null) {

                $file = 'moodle';

            }

            $string = array();

            // First load english pack.

            if (!file_exists("$CFG->dirroot/lang/en/$file.php")) {

                return array();

            }

            include("$CFG->dirroot/lang/en/$file.php");

            $enstring = $string;

            // And then corresponding local if present and allowed.

            if (!$disablelocal and file_exists("$this->localroot/en_local/$file.php")) {

                include("$this->localroot/en_local/$file.php");

            }

            // Now loop through all langs in correct order.

            $deps = $this->get_language_dependencies($lang);

            foreach ($deps as $dep) {

                // The main lang string location.

                if (file_exists("$this->otherroot/$dep/$file.php")) {

                    include("$this->otherroot/$dep/$file.php");

                }

                if (!$disablelocal and file_exists("$this->localroot/{$dep}_local/$file.php")) {

                    include("$this->localroot/{$dep}_local/$file.php");

                }

            }

        } else {

            if (!$location = core_component::get_plugin_directory($plugintype, $pluginname) or !is_dir($location)) {

                return array();

            }

            if ($plugintype === 'mod') {

                // Bloody mod hack.

                $file = $pluginname;

            } else {

                $file = $plugintype . '_' . $pluginname;

            }

            $string = array();

            // First load English pack.

            if (!file_exists("$location/lang/en/$file.php")) {

                // English pack does not exist, so do not try to load anything else.

                return array();

            }

            include("$location/lang/en/$file.php");

            $enstring = $string;

            // And then corresponding local english if present.

            if (!$disablelocal and file_exists("$this->localroot/en_local/$file.php")) {

                include("$this->localroot/en_local/$file.php");

            }

            // Now loop through all langs in correct order.

            $deps = $this->get_language_dependencies($lang);

            foreach ($deps as $dep) {

                // Legacy location - used by contrib only.

                if (file_exists("$location/lang/$dep/$file.php")) {

                    include("$location/lang/$dep/$file.php");

                }

                // The main lang string location.

                if (file_exists("$this->otherroot/$dep/$file.php")) {

                    include("$this->otherroot/$dep/$file.php");

                }

                // Local customisations.

                if (!$disablelocal and file_exists("$this->localroot/{$dep}_local/$file.php")) {

                    include("$this->localroot/{$dep}_local/$file.php");

                }

            }

        }

        // We do not want any extra strings from other languages - everything must be in en lang pack.

        $string = array_intersect_key($string, $enstring);

        if (!$disablelocal) {

            // Now we have a list of strings from all possible sources,

            // cache it in MUC cache if not already there.

            if ($cachedstring === false) {

                $this->cache->set($cachekey, $string);

            }

        }

        return $string;

    }

    /**

     * Parses all deprecated.txt in all plugins lang locations and returns the list of deprecated strings.

     *

     * Static variable is used for caching, this function is only called in dev environment.

     *

     * @return array of deprecated strings in the same format they appear in deprecated.txt files: "identifier,component"

     *     where component is a normalised component (i.e. "core_moodle", "mod_assign", etc.)

     */

    protected function load_deprecated_strings() {

        global $CFG;

        if ($this->cacheddeprecated !== null) {

            return $this->cacheddeprecated;

        }

        $this->cacheddeprecated = array();

        $content = '';

        $filename = $CFG->dirroot . '/lang/en/deprecated.txt';

        if (file_exists($filename)) {

            $content .= file_get_contents($filename);

        }

        foreach (core_component::get_plugin_types() as $plugintype => $plugintypedir) {

            foreach (core_component::get_plugin_list($plugintype) as $pluginname => $plugindir) {

                $filename = $plugindir.'/lang/en/deprecated.txt';

                if (file_exists($filename)) {

                    $content .= "\n". file_get_contents($filename);

                }

            }

        }

        $strings = preg_split('/\s*\n\s*/', $content, -1, PREG_SPLIT_NO_EMPTY);

        $this->cacheddeprecated = array_flip($strings);

        return $this->cacheddeprecated;

    }

    /**

     * Has string been deprecated?

     *

     * Usually checked only inside get_string() to display debug warnings.

     *

     * @param string $identifier The identifier of the string to search for

     * @param string $component The module the string is associated with

     * @return bool true if deprecated

     */

    public function string_deprecated($identifier, $component) {

        $deprecated = $this->load_deprecated_strings();

        list($plugintype, $pluginname) = core_component::normalize_component($component);

        $normcomponent = $pluginname ? ($plugintype . '_' . $pluginname) : $plugintype;

        return isset($deprecated[$identifier . ',' . $normcomponent]);

    }

    /**

     * Does the string actually exist?

     *

     * get_string() is throwing debug warnings, sometimes we do not want them

     * or we want to display better explanation of the problem.

     * Note: Use with care!

     *

     * @param string $identifier The identifier of the string to search for

     * @param string $component The module the string is associated with

     * @return boot true if exists

     */

    public function string_exists($identifier, $component) {

        $lang = current_language();

        $string = $this->load_component_strings($component, $lang);

        return isset($string[$identifier]);

    }

    /**

     * Get String returns a requested string

     *

     * @param string $identifier The identifier of the string to search for

     * @param string $component The module the string is associated with

     * @param string|object|array $a An object, string or number that can be used

     *      within translation strings

     * @param string $lang moodle translation language, null means use current

     * @return string The String !

     */

    public function get_string($identifier, $component = '', $a = null, $lang = null) {

        global $CFG;

        $this->countgetstring++;

        // There are very many uses of these time formatting strings without the 'langconfig' component,

        // it would not be reasonable to expect that all of them would be converted during 2.0 migration.

        static $langconfigstrs = array(

            'strftimedate' => 1,

            'strftimedatefullshort' => 1,

            'strftimedateshort' => 1,

            'strftimedatetime' => 1,

            'strftimedatetimeaccurate' => 1,

            'strftimedatetimeshort' => 1,

            'strftimedatetimeshortaccurate' => 1,

            'strftimedaydate' => 1,

            'strftimedaydatetime' => 1,

            'strftimedayshort' => 1,

            'strftimedaytime' => 1,

            'strftimemonth' => 1,

            'strftimemonthyear' => 1,

            'strftimerecent' => 1,

            'strftimerecentfull' => 1,

            'strftimetime' => 1);

        if (empty($component)) {

            if (isset($langconfigstrs[$identifier])) {

                $component = 'langconfig';

            } else {

                $component = 'moodle';

            }

        }

        if ($lang === null) {

            $lang = current_language();

        }

        $string = $this->load_component_strings($component, $lang);

        if (!isset($string[$identifier])) {

            if ($component === 'pix' or $component === 'core_pix') {

                // This component contains only alt tags for emoticons, not all of them are supposed to be defined.

                return '';

            }

            if ($identifier === 'parentlanguage' and ($component === 'langconfig' or $component === 'core_langconfig')) {

                // Identifier parentlanguage is a special string, undefined means use English if not defined.

                return 'en';

            }

            // Do not rebuild caches here!

            // Devs need to learn to purge all caches after any change or disable $CFG->langstringcache.

            if (!isset($string[$identifier])) {

                // The string is still missing - should be fixed by developer.

                if ($CFG->debugdeveloper) {

                    list($plugintype, $pluginname) = core_component::normalize_component($component);

                    if ($plugintype === 'core') {

                        $file = "lang/en/{$component}.php";

                    } else if ($plugintype == 'mod') {

                        $file = "mod/{$pluginname}/lang/en/{$pluginname}.php";

                    } else {

                        $path = core_component::get_plugin_directory($plugintype, $pluginname);

                        $file = "{$path}/lang/en/{$plugintype}_{$pluginname}.php";

                    }

                    debugging("Invalid get_string() identifier: '{$identifier}' or component '{$component}'. " .

                    "Perhaps you are missing \$string['{$identifier}'] = ''; in {$file}?", DEBUG_DEVELOPER);

                }

                return "[[$identifier]]";

            }

        }

        $string = $string[$identifier];

        if ($a !== null) {

            // Process array's and objects (except lang_strings).

            if (is_array($a) or (is_object($a) && !($a instanceof Stringable))) {

                $a = (array)$a;

                $search = array();

                $replace = array();

                foreach ($a as $key => $value) {

                    if (is_int($key)) {

                        // We do not support numeric keys - sorry!

                        continue;

                    }

                    if (is_array($value) or (is_object($value) && !($value instanceof Stringable))) {

                        // We support just string or lang_string as value.

                        continue;

                    }

                    $search[]  = '{$a->'.$key.'}';

                    $replace[] = (string)$value;

                }

                if ($search) {

                    $string = str_replace($search, $replace, $string);

                }

            } else {

                $string = str_replace('{$a}', (string)$a, $string);

            }

        }

        if ($CFG->debugdeveloper) {

            // Display a debugging message if sting exists but was deprecated.

            if ($this->string_deprecated($identifier, $component)) {

                list($plugintype, $pluginname) = core_component::normalize_component($component);

                $normcomponent = $pluginname ? ($plugintype . '_' . $pluginname) : $plugintype;

                debugging("String [{$identifier},{$normcomponent}] is deprecated. ".

                    'Either you should no longer be using that string, or the string has been incorrectly deprecated, in which case you should report this as a bug. '.

                    'Please refer to https://moodledev.io/general/projects/api/string-deprecation', DEBUG_DEVELOPER);

            }

        }

        return $string;

    }

    /**

     * Returns information about the core_string_manager performance.

     *

     * @return array

     */

    public function get_performance_summary() {

        return array(array(

            'langcountgetstring' => $this->countgetstring,

        ), array(

            'langcountgetstring' => 'get_string calls',

        ));

    }

    /**

     * Returns a localised list of all country names, sorted by localised name.

     *

     * @param bool $returnall return all or just enabled

     * @param string $lang moodle translation language, null means use current

     * @return array two-letter country code => translated name.

     */

    public function get_list_of_countries($returnall = false, $lang = null) {

        global $CFG;

        if ($lang === null) {

            $lang = current_language();

        }

        $countries = $this->load_component_strings('core_countries', $lang);

        core_collator::asort($countries);

        if (!$returnall and !empty($CFG->allcountrycodes)) {

            $enabled = explode(',', $CFG->allcountrycodes);

            $return = array();

            foreach ($enabled as $c) {

                if (isset($countries[$c])) {

                    $return[$c] = $countries[$c];

                }

            }

            if (!empty($return)) {

                return $return;

            }

        }

        return $countries;

    }

    /**

     * Returns a localised list of languages, sorted by code keys.

     *

     * @param string $lang moodle translation language, null means use current

     * @param string $standard language list standard

     *    - iso6392: three-letter language code (ISO 639-2/T) => translated name

     *    - iso6391: two-letter language code (ISO 639-1) => translated name

     * @return array language code => translated name

     */

    public function get_list_of_languages($lang = null, $standard = 'iso6391') {

        if ($lang === null) {

            $lang = current_language();

        }

        if ($standard === 'iso6392') {

            $langs = $this->load_component_strings('core_iso6392', $lang);

            ksort($langs);

            return $langs;

        } else if ($standard === 'iso6391') {

            $langs2 = $this->load_component_strings('core_iso6392', $lang);

            static $mapping = array('aar' => 'aa', 'abk' => 'ab', 'afr' => 'af', 'aka' => 'ak', 'sqi' => 'sq', 'amh' => 'am', 'ara' => 'ar', 'arg' => 'an', 'hye' => 'hy',

                'asm' => 'as', 'ava' => 'av', 'ave' => 'ae', 'aym' => 'ay', 'aze' => 'az', 'bak' => 'ba', 'bam' => 'bm', 'eus' => 'eu', 'bel' => 'be', 'ben' => 'bn', 'bih' => 'bh',

                'bis' => 'bi', 'bos' => 'bs', 'bre' => 'br', 'bul' => 'bg', 'mya' => 'my', 'cat' => 'ca', 'cha' => 'ch', 'che' => 'ce', 'zho' => 'zh', 'chu' => 'cu', 'chv' => 'cv',

                'cor' => 'kw', 'cos' => 'co', 'cre' => 'cr', 'ces' => 'cs', 'dan' => 'da', 'div' => 'dv', 'nld' => 'nl', 'dzo' => 'dz', 'eng' => 'en', 'epo' => 'eo', 'est' => 'et',

                'ewe' => 'ee', 'fao' => 'fo', 'fij' => 'fj', 'fin' => 'fi', 'fra' => 'fr', 'fry' => 'fy', 'ful' => 'ff', 'kat' => 'ka', 'deu' => 'de', 'gla' => 'gd', 'gle' => 'ga',

                'glg' => 'gl', 'glv' => 'gv', 'ell' => 'el', 'grn' => 'gn', 'guj' => 'gu', 'hat' => 'ht', 'hau' => 'ha', 'heb' => 'he', 'her' => 'hz', 'hin' => 'hi', 'hmo' => 'ho',

                'hrv' => 'hr', 'hun' => 'hu', 'ibo' => 'ig', 'isl' => 'is', 'ido' => 'io', 'iii' => 'ii', 'iku' => 'iu', 'ile' => 'ie', 'ina' => 'ia', 'ind' => 'id', 'ipk' => 'ik',

                'ita' => 'it', 'jav' => 'jv', 'jpn' => 'ja', 'kal' => 'kl', 'kan' => 'kn', 'kas' => 'ks', 'kau' => 'kr', 'kaz' => 'kk', 'khm' => 'km', 'kik' => 'ki', 'kin' => 'rw',

                'kir' => 'ky', 'kom' => 'kv', 'kon' => 'kg', 'kor' => 'ko', 'kua' => 'kj', 'kur' => 'ku', 'lao' => 'lo', 'lat' => 'la', 'lav' => 'lv', 'lim' => 'li', 'lin' => 'ln',

                'lit' => 'lt', 'ltz' => 'lb', 'lub' => 'lu', 'lug' => 'lg', 'mkd' => 'mk', 'mah' => 'mh', 'mal' => 'ml', 'mri' => 'mi', 'mar' => 'mr', 'msa' => 'ms', 'mlg' => 'mg',

                'mlt' => 'mt', 'mon' => 'mn', 'nau' => 'na', 'nav' => 'nv', 'nbl' => 'nr', 'nde' => 'nd', 'ndo' => 'ng', 'nep' => 'ne', 'nno' => 'nn', 'nob' => 'nb', 'nor' => 'no',

                'nya' => 'ny', 'oci' => 'oc', 'oji' => 'oj', 'ori' => 'or', 'orm' => 'om', 'oss' => 'os', 'pan' => 'pa', 'fas' => 'fa', 'pli' => 'pi', 'pol' => 'pl', 'por' => 'pt',

                'pus' => 'ps', 'que' => 'qu', 'roh' => 'rm', 'ron' => 'ro', 'run' => 'rn', 'rus' => 'ru', 'sag' => 'sg', 'san' => 'sa', 'sin' => 'si', 'slk' => 'sk', 'slv' => 'sl',

                'sme' => 'se', 'smo' => 'sm', 'sna' => 'sn', 'snd' => 'sd', 'som' => 'so', 'sot' => 'st', 'spa' => 'es', 'srd' => 'sc', 'srp' => 'sr', 'ssw' => 'ss', 'sun' => 'su',

                'swa' => 'sw', 'swe' => 'sv', 'tah' => 'ty', 'tam' => 'ta', 'tat' => 'tt', 'tel' => 'te', 'tgk' => 'tg', 'tgl' => 'tl', 'tha' => 'th', 'bod' => 'bo', 'tir' => 'ti',

                'ton' => 'to', 'tsn' => 'tn', 'tso' => 'ts', 'tuk' => 'tk', 'tur' => 'tr', 'twi' => 'tw', 'uig' => 'ug', 'ukr' => 'uk', 'urd' => 'ur', 'uzb' => 'uz', 'ven' => 've',

                'vie' => 'vi', 'vol' => 'vo', 'cym' => 'cy', 'wln' => 'wa', 'wol' => 'wo', 'xho' => 'xh', 'yid' => 'yi', 'yor' => 'yo', 'zha' => 'za', 'zul' => 'zu');

            $langs1 = array();

            foreach ($mapping as $c2 => $c1) {

                $langs1[$c1] = $langs2[$c2];

            }

            ksort($langs1);

            return $langs1;

        } else {

            debugging('Unsupported $standard parameter in get_list_of_languages() method: '.$standard);

        }

        return array();

    }

    /**

     * Checks if the translation exists for the language

     *

     * @param string $lang moodle translation language code

     * @param bool $includeall include also disabled translations

     * @return bool true if exists

     */

    public function translation_exists($lang, $includeall = true) {

        $translations = $this->get_list_of_translations($includeall);

        return isset($translations[$lang]);

    }

    /**

     * Returns localised list of installed translations

     *

     * @param bool $returnall return all or just enabled

     * @return array moodle translation code => localised translation name

     */

    public function get_list_of_translations($returnall = false) {

        global $CFG;

        $languages = array();

        $cachekey = 'list_'.$this->get_key_suffix();

        $cachedlist = $this->menucache->get($cachekey);

        if ($cachedlist !== false) {

            // The cache content is valid.

            if ($returnall or empty($this->translist)) {

                return $cachedlist;

            }

            // Return only enabled translations.

            foreach ($cachedlist as $langcode => $langname) {

                if (array_key_exists($langcode, $this->translist)) {

                    $languages[$langcode] = !empty($this->transaliases[$langcode]) ? $this->transaliases[$langcode] : $langname;

                }

            }

            // If there are no valid enabled translations, then return all languages.

            if (!empty($languages)) {

                return $languages;

            } else {

                return $cachedlist;

            }

        }

        // Get all languages available in system.

        $langdirs = get_list_of_plugins('', 'en', $this->otherroot);

        $langdirs["$CFG->dirroot/lang/en"] = 'en';

        // We use left to right mark to demark the shortcodes contained in LTR brackets, but we need to do

        // this hacky thing to have the utf8 char until we go php7 minimum and can simply put \u200E in

        // a double quoted string.

        $lrm = json_decode('"\u200E"');

        // Loop through all langs and get info.

        foreach ($langdirs as $lang) {

            if (strrpos($lang, '_local') !== false) {

                // Just a local tweak of some other lang pack.

                continue;

            }

            if (strrpos($lang, '_utf8') !== false) {

                // Legacy 1.x lang pack.

                continue;

            }

            if ($lang !== clean_param($lang, PARAM_SAFEDIR)) {

                // Invalid lang pack name!

                continue;

            }

            $string = $this->load_component_strings('langconfig', $lang);

            if (!empty($string['thislanguage'])) {

                $languages[$lang] = $string['thislanguage'].' '.$lrm.'('. $lang .')'.$lrm;

            }

        }

        core_collator::asort($languages);

        // Cache the list so that it can be used next time.

        $this->menucache->set($cachekey, $languages);

        if ($returnall or empty($this->translist)) {

            return $languages;

        }

        $cachedlist = $languages;

        // Return only enabled translations.

        $languages = array();

        foreach ($cachedlist as $langcode => $langname) {

            if (isset($this->translist[$langcode])) {

                $languages[$langcode] = !empty($this->transaliases[$langcode]) ? $this->transaliases[$langcode] : $langname;

            }

        }

        // If there are no valid enabled translations, then return all languages.

        if (!empty($languages)) {

            return $languages;

        } else {

            return $cachedlist;

        }

    }

    /**

     * Returns localised list of currencies.

     *

     * @param string $lang moodle translation language, null means use current

     * @return array currency code => localised currency name

     */

    public function get_list_of_currencies($lang = null) {

        if ($lang === null) {

            $lang = current_language();

        }

        $currencies = $this->load_component_strings('core_currencies', $lang);

        asort($currencies);

        return $currencies;

    }

    /**

     * Clears both in-memory and on-disk caches

     * @param bool $phpunitreset true means called from our PHPUnit integration test reset

     */

    public function reset_caches($phpunitreset = false) {

        // Clear the on-disk disk with aggregated string files.

        $this->cache->purge();

        $this->menucache->purge();

        if (!$phpunitreset) {

            // Increment the revision counter.

            $langrev = get_config('core', 'langrev');

            $next = time();

            if ($langrev !== false and $next <= $langrev and $langrev - $next < 60*60) {

                // This resolves problems when reset is requested repeatedly within 1s,

                // the < 1h condition prevents accidental switching to future dates

                // because we might not recover from it.

                $next = $langrev+1;

            }

            set_config('langrev', $next);

        }

        // Lang packs use PHP files in dataroot, it is better to invalidate opcode caches.

        if (function_exists('opcache_reset')) {

            opcache_reset();

        }

    }

    /**

     * Returns cache key suffix, this enables us to store string + lang menu

     * caches in local caches on cluster nodes. We can not use prefix because

     * it would cause problems when creating subdirs in cache file store.

     * @return string

     */

    protected function get_key_suffix() {

        $rev = $this->get_revision();

        if ($rev < 0) {

            // Simple keys do not like minus char.

            $rev = 0;

        }

        return $rev;

    }

    /**

     * Returns string revision counter, this is incremented after any string cache reset.

     * @return int lang string revision counter, -1 if unknown

     */

    public function get_revision() {

        global $CFG;

        if (empty($CFG->langstringcache)) {

            return -1;

        }

        if (isset($CFG->langrev)) {

            return (int)$CFG->langrev;

        } else {

            return -1;

        }

    }

    /**

     * Helper method that recursively loads all parents of the given language.

     *

     * @see self::get_language_dependencies()

     * @param string $lang language code

     * @param array $stack list of parent languages already populated in previous recursive calls

     * @return array list of all parents of the given language with the $lang itself added as the last element

     */

    protected function populate_parent_languages($lang, array $stack = array()) {

        // English does not have a parent language.

        if ($lang === 'en') {

            return $stack;

        }

        // Prevent circular dependency (and thence the infinitive recursion loop).

        if (in_array($lang, $stack)) {

            return $stack;

        }

        // Load language configuration and look for the explicit parent language.

        if (!file_exists("$this->otherroot/$lang/langconfig.php")) {

            return $stack;

        }

        $string = array();

        include("$this->otherroot/$lang/langconfig.php");

        if (empty($string['parentlanguage']) or $string['parentlanguage'] === 'en') {

            return array_merge(array($lang), $stack);

        }

        $parentlang = $string['parentlanguage'];

        return $this->populate_parent_languages($parentlang, array_merge(array($lang), $stack));

    }

}