PHP 5.3 closure-based implementation of curry(); old implementation used as fallback for older PHP versions. Added unit tests to confirm they both work!

lib/curry.php

@@ -0,0 +1,36 @@
+<?php
+/*
+ * StatusNet - the distributed open-source microblogging tool
+ * Copyright (C) 2008, 2009, StatusNet, Inc.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * PHP 5.3 implementation of function currying, using native closures.
+ * On 5.2 and lower we use the fallback implementation in util.php
+ *
+ * @param callback $fn
+ * @param ... any remaining arguments will be appended to call-time params
+ * @return callback
+ */
+function curry($fn) {
+    $extra_args = func_get_args();
+    array_shift($extra_args);
+    return function() use ($fn, $extra_args) {
+        $args = func_get_args();
+        return call_user_func_array($fn,
+            array_merge($args, $extra_args));
+    };
+}

lib/util.php

@@ -523,19 +523,23 @@ function callback_helper($matches, $callback, $notice_id) {
     return substr($matches[0],0,$left) . $result . substr($matches[0],$right);
 }
 
-function curry($fn) {
+if (version_compare(PHP_VERSION, '5.3.0', 'ge')) {
-    //TODO switch to a PHP 5.3 function closure based approach if PHP 5.3 is used
+    // lambda implementation in a separate file; PHP 5.2 won't parse it.
-    $args = func_get_args();
+    require_once INSTALLDIR . "/lib/curry.php";
-    array_shift($args);
+} else {
-    $id = uniqid('_partial');
+    function curry($fn) {
-    $GLOBALS[$id] = array($fn, $args);
+        $args = func_get_args();
-    return create_function('',
+        array_shift($args);
-                           '$args = func_get_args(); '.
+        $id = uniqid('_partial');
-                           'return call_user_func_array('.
+        $GLOBALS[$id] = array($fn, $args);
-                           '$GLOBALS["'.$id.'"][0],'.
+        return create_function('',
-                           'array_merge('.
+                               '$args = func_get_args(); '.
-                           '$args,'.
+                               'return call_user_func_array('.
-                           '$GLOBALS["'.$id.'"][1]));');
+                               '$GLOBALS["'.$id.'"][0],'.
+                               'array_merge('.
+                               '$args,'.
+                               '$GLOBALS["'.$id.'"][1]));');
+    }
 }
 
 function common_linkify($url) {

tests/CurryTest.php

@@ -0,0 +1,72 @@
+<?php
+
+if (isset($_SERVER) && array_key_exists('REQUEST_METHOD', $_SERVER)) {
+    print "This script must be run from the command line\n";
+    exit();
+}
+
+define('INSTALLDIR', realpath(dirname(__FILE__) . '/..'));
+define('STATUSNET', true);
+define('LACONICA', true);
+
+require_once INSTALLDIR . '/lib/common.php';
+
+class CurryTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @dataProvider provider
+     *
+     */
+    public function testProduction($callback, $curry_params, $call_params, $expected)
+    {
+        $params = array_merge(array($callback), $curry_params);
+        $curried = call_user_func_array('curry', $params);
+        $result = call_user_func_array($curried, $call_params);
+        $this->assertEquals($expected, $result);
+    }
+
+    static public function provider()
+    {
+        $obj = new CurryTestHelperObj('oldval');
+        return array(array(array('CurryTest', 'callback'),
+                           array('curried'),
+                           array('called'),
+                           'called|curried'),
+                     array(array('CurryTest', 'callback'),
+                           array('curried1', 'curried2'),
+                           array('called1', 'called2'),
+                           'called1|called2|curried1|curried2'),
+                     array(array('CurryTest', 'callbackObj'),
+                           array($obj),
+                           array('newval1'),
+                           'oldval|newval1'),
+                     // Confirm object identity is retained...
+                     array(array('CurryTest', 'callbackObj'),
+                           array($obj),
+                           array('newval2'),
+                           'newval1|newval2'));
+    }
+
+    static function callback()
+    {
+        $args = func_get_args();
+        return implode("|", $args);
+    }
+
+    static function callbackObj($val, $obj)
+    {
+        $old = $obj->val;
+        $obj->val = $val;
+        return "$old|$val";
+    }
+}
+
+class CurryTestHelperObj
+{
+    public $val='';
+
+    function __construct($val)
+    {
+        $this->val = $val;
+    }
+}