Add CallbackComparator

Author: marcospassos

CHANGELOG.md

@@ -1,6 +1,10 @@
 Changelog
 =========
 
+* 1.0.0-beta (2016-07-17)
+
+ * Added `CallbackComparator`
+
 * 1.0.0-beta (2016-05-06)
 
- * first beta release
+ * First beta release

src/Comparator/CallbackComparator.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace PhpCommon\Comparison\Comparator;
+
+use PhpCommon\Comparison\Comparator;
+
+/**
+ * A comparator the uses a callback to compare values.
+ *
+ * This comparator is useful when simple, one-off comparators need to be
+ * created. It can be used to change or extend existing comparators in order to
+ * achieve new ones that better fit to the underlying needs.
+ *
+ * @author Marcos Passos <marcos@marcospassos.com>
+ */
+class CallbackComparator implements Comparator
+{
+    /**
+     * @var callable
+     */
+    protected $callback;
+
+    /**
+     * CallbackComparator constructor.
+     *
+     * @param callable $callback
+     */
+    public function __construct(callable $callback)
+    {
+        $this->callback = $callback;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function compare($left, $right)
+    {
+        return call_user_func_array($this->callback, [$left, $right]);
+    }
+}

tests/Comparator/CallbackComparatorTest.php

@@ -0,0 +1,43 @@
+<?php
+
+/**
+ * This file is part of the phpcommon/comparison package.
+ *
+ * (c) Marcos Passos <marcos@marcospassos.com>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace PhpCommon\Comparison\Tests\Comparator;
+
+use PhpCommon\Comparison\Comparator\CallbackComparator;
+use PHPUnit_Framework_TestCase;
+
+/**
+ * @since  1.0
+ *
+ * @author Marcos Passos <marcos@croct.com>
+ */
+class CallbackComparatorTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @testdox The compare() method delegates calls to the callback function
+     */
+    public function testCompareMethodDelegatesCallsToTheCallbackFunction()
+    {
+        $callback = $this->getMockBuilder('stdClass')
+            ->setMethods(['callback'])
+            ->getMock()
+        ;
+
+        $callback->expects($this->once())
+            ->method('callback')
+            ->with($this->identicalTo('foo'), $this->identicalTo('bar'))
+            ->willReturn(-1)
+        ;
+
+        $comparator = new CallbackComparator([$callback, 'callback']);
+        $this->assertSame(-1, $comparator->compare('foo', 'bar'));
+    }
+}