MDL-57972 mustache: add shortentext template helper

Part of MDL-55611

lib/amd/src/templates.js

@@ -29,14 +29,14 @@ define(['core/mustache',
          'core/str',
          'core/notification',
          'core/url',
-         'core/log',
          'core/config',
          'core/localstorage',
          'core/event',
          'core/yui',
-         'core/log'
+         'core/log',
+         'core/truncate'
        ],
-       function(mustache, $, ajax, str, notification, coreurl, log, config, storage, event, Y, Log) {
+       function(mustache, $, ajax, str, notification, coreurl, config, storage, event, Y, Log, Truncate) {
 
     // Module variables.
     /** @var {Number} uniqInstances Count of times this constructor has been called. */
@@ -261,6 +261,33 @@ define(['core/mustache',
         return '"' + content + '"';
     };
 
+    /**
+     * Shorten text helper to truncate text and append a trailing ellipsis.
+     *
+     * @method shortenTextHelper
+     * @private
+     * @param {object} context The current mustache context.
+     * @param {string} sectionText The text to parse the arguments from.
+     * @param {function} helper Used to render subsections of the text.
+     * @return {string}
+     */
+    Renderer.prototype.shortenTextHelper = function(context, sectionText, helper) {
+        // Non-greedy split on comma to grab section text into the length and
+        // text parts.
+        var regex = /(.*?),(.*)/;
+        var parts = sectionText.match(regex);
+        // The length is the part matched in the first set of parethesis.
+        var length = parts[1].trim();
+        // The length is the part matched in the second set of parethesis.
+        var text = parts[2].trim();
+        var content = helper(text, context);
+        return Truncate.truncate(content, {
+            length: length,
+            words: true,
+            ellipsis: '...'
+        });
+    };
+
     /**
      * Add some common helper functions to all context objects passed to templates.
      * These helpers match exactly the helpers available in php.
@@ -287,6 +314,9 @@ define(['core/mustache',
         context.quote = function() {
           return this.quoteHelper.bind(this, context);
         }.bind(this);
+        context.shortentext = function() {
+          return this.shortenTextHelper.bind(this, context);
+        }.bind(this);
         context.globals = {config: config};
         context.currentTheme = themeName;
     };

lib/classes/output/mustache_shorten_text_helper.php

@@ -0,0 +1,64 @@
+<?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/>.
+
+/**
+ * Mustache helper shorten text.
+ *
+ * @package    core
+ * @category   output
+ * @copyright  2017 Ryan Wyllie <[email protected]>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+namespace core\output;
+
+defined('MOODLE_INTERNAL') || die();
+
+use Mustache_LambdaHelper;
+use renderer_base;
+
+/**
+ * This class will call shorten_text with the section content.
+ *
+ * @copyright  2017 Ryan Wyllie <[email protected]>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class mustache_shorten_text_helper {
+
+    /**
+     * Read a length and text component from the string.
+     *
+     * {{#shortentext}}50,Some test to shorten{{/shortentext}}
+     *
+     * Both args are required. The length must come first.
+     *
+     * @param string $args The text to parse for arguments.
+     * @param Mustache_LambdaHelper $helper Used to render nested mustache variables.
+     * @return string
+     */
+    public function shorten($args, Mustache_LambdaHelper $helper) {
+        // Split the text into an array of variables.
+        list($length, $text) = explode(',', $args, 2);
+        $length = trim($length);
+        $text = trim($text);
+
+        // Allow mustache tags in the text.
+        $text = $helper->render($text);
+
+        return shorten_text($text, $length);
+    }
+}
+

lib/outputrenderers.php

@@ -91,6 +91,7 @@ class renderer_base {
             $quotehelper = new \core\output\mustache_quote_helper();
             $jshelper = new \core\output\mustache_javascript_helper($this->page->requires);
             $pixhelper = new \core\output\mustache_pix_helper($this);
+            $shortentexthelper = new \core\output\mustache_shorten_text_helper();
 
             // We only expose the variables that are exposed to JS templates.
             $safeconfig = $this->page->requires->get_config_for_javascript($this->page, $this);
@@ -99,7 +100,8 @@ class renderer_base {
                              'str' => array($stringhelper, 'str'),
                              'quote' => array($quotehelper, 'quote'),
                              'js' => array($jshelper, 'help'),
-                             'pix' => array($pixhelper, 'pix'));
+                             'pix' => array($pixhelper, 'pix'),
+                             'shortentext' => array($shortentexthelper, 'shorten'));
 
             $this->mustache = new Mustache_Engine(array(
                 'cache' => $cachedir,