MDL-61307 core: Add component_class_callback functionality

lib/moodlelib.php

@@ -7727,6 +7727,37 @@ function component_callback_exists($component, $function) {
     return false;
 }
 
+/**
+ * Call the specified callback method on the provided class.
+ *
+ * If the callback returns null, then the default value is returned instead.
+ * If the class does not exist, then the default value is returned.
+ *
+ * @param   string      $classname The name of the class to call upon.
+ * @param   string      $methodname The name of the staticically defined method on the class.
+ * @param   array       $params The arguments to pass into the method.
+ * @param   mixed       $default The default value.
+ * @return  mixed       The return value.
+ */
+function component_class_callback($classname, $methodname, array $params, $default = null) {
+    if (!class_exists($classname)) {
+        return $default;
+    }
+
+    if (!method_exists($classname, $methodname)) {
+        return $default;
+    }
+
+    $fullfunction = $classname . '::' . $methodname;
+    $result = call_user_func_array($fullfunction, $params);
+
+    if (null === $result) {
+        return $default;
+    } else {
+        return $result;
+    }
+}
+
 /**
  * Checks whether a plugin supports a specified feature.
  *

lib/tests/fixtures/component_class_callback_example.php

@@ -0,0 +1,61 @@
+<?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/>.
+
+/**
+ * Fixtures for component_class_callback tests.
+ *
+ * @package    core
+ * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+/**
+ * Class fixture for component_class_callback.
+ *
+ * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class test_component_class_callback_example {
+    /**
+     * Function which returns the input value.
+     *
+     * @param   mixed   $output
+     * @return  mixed
+     */
+    public static function method_returns_value($output) {
+        return $output;
+    }
+
+    /**
+     * Function which returns all args.
+     *
+     * @return  mixed
+     */
+    public static function method_returns_all_params() {
+        return count(func_get_args());
+    }
+}
+
+/**
+ * Class fixture for component_class_callback which extends another class.
+ *
+ * @copyright  2018 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class test_component_class_callback_child_example extends test_component_class_callback_example {
+}

lib/tests/moodlelib_test.php

@@ -3588,4 +3588,130 @@ public function test_unserialize_array() {
         $a = array('aggregatesonly' => [51, 34], 'gradesonly' => [21, 45, 78]);
         $this->assertEquals($a, unserialize_array(serialize($a)));
     }
+
+    /**
+     * Test that the component_class_callback returns the correct default value when the class was not found.
+     *
+     * @dataProvider component_class_callback_default_provider
+     * @param $default
+     */
+    public function test_component_class_callback_not_found($default) {
+        $this->assertSame($default, component_class_callback('thisIsNotTheClassYouWereLookingFor', 'anymethod', [], $default));
+    }
+
+    /**
+     * Test that the component_class_callback returns the correct default value when the class was not found.
+     *
+     * @dataProvider component_class_callback_default_provider
+     * @param $default
+     */
+    public function test_component_class_callback_method_not_found($default) {
+        require_once(__DIR__ . '/fixtures/component_class_callback_example.php');
+
+        $this->assertSame($default, component_class_callback(test_component_class_callback_example::class, 'this_is_not_the_method_you_were_looking_for', ['abc'], $default));
+    }
+
+    /**
+     * Test that the component_class_callback returns the default when the method returned null.
+     *
+     * @dataProvider component_class_callback_default_provider
+     * @param $default
+     */
+    public function test_component_class_callback_found_returns_null($default) {
+        require_once(__DIR__ . '/fixtures/component_class_callback_example.php');
+
+        $this->assertSame($default, component_class_callback(test_component_class_callback_example::class, 'method_returns_value', [null], $default));
+        $this->assertSame($default, component_class_callback(test_component_class_callback_child_example::class, 'method_returns_value', [null], $default));
+    }
+
+    /**
+     * Test that the component_class_callback returns the expected value and not the default when there was a value.
+     *
+     * @dataProvider component_class_callback_data_provider
+     * @param $default
+     */
+    public function test_component_class_callback_found_returns_value($value) {
+        require_once(__DIR__ . '/fixtures/component_class_callback_example.php');
+
+        $this->assertSame($value, component_class_callback(test_component_class_callback_example::class, 'method_returns_value', [$value], 'This is not the value you were looking for'));
+        $this->assertSame($value, component_class_callback(test_component_class_callback_child_example::class, 'method_returns_value', [$value], 'This is not the value you were looking for'));
+    }
+
+    /**
+     * Test that the component_class_callback handles multiple params correctly.
+     *
+     * @dataProvider component_class_callback_multiple_params_provider
+     * @param $default
+     */
+    public function test_component_class_callback_found_accepts_multiple($params, $count) {
+        require_once(__DIR__ . '/fixtures/component_class_callback_example.php');
+
+        $this->assertSame($count, component_class_callback(test_component_class_callback_example::class, 'method_returns_all_params', $params, 'This is not the value you were looking for'));
+        $this->assertSame($count, component_class_callback(test_component_class_callback_child_example::class, 'method_returns_all_params', $params, 'This is not the value you were looking for'));
+    }
+
+    /**
+     * Data provider with list of default values for user in component_class_callback tests.
+     *
+     * @return array
+     */
+    public function component_class_callback_default_provider() {
+        return [
+            'null' => [null],
+            'empty string' => [''],
+            'string' => ['This is a string'],
+            'int' => [12345],
+            'stdClass' => [(object) ['this is my content']],
+            'array' => [['a' => 'b',]],
+        ];
+    }
+
+    /**
+     * Data provider with list of default values for user in component_class_callback tests.
+     *
+     * @return array
+     */
+    public function component_class_callback_data_provider() {
+        return [
+            'empty string' => [''],
+            'string' => ['This is a string'],
+            'int' => [12345],
+            'stdClass' => [(object) ['this is my content']],
+            'array' => [['a' => 'b',]],
+        ];
+    }
+
+    /**
+     * Data provider with list of default values for user in component_class_callback tests.
+     *
+     * @return array
+     */
+    public function component_class_callback_multiple_params_provider() {
+        return [
+            'empty array' => [
+                [],
+                0,
+            ],
+            'string value' => [
+                ['one'],
+                1,
+            ],
+            'string values' => [
+                ['one', 'two'],
+                2,
+            ],
+            'arrays' => [
+                [[], []],
+                2,
+            ],
+            'nulls' => [
+                [null, null, null, null],
+                4,
+            ],
+            'mixed' => [
+                ['a', 1, null, (object) [], []],
+                5,
+            ],
+        ];
+    }
 }