Add "count" helper

src/Collection/CountHelper.php

@@ -0,0 +1,52 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Collection;
+
+use Handlebars\Context;
+use Handlebars\Helper as HelperInterface;
+use Handlebars\Template;
+
+/**
+ * Returns count of items of the collection.
+ *
+ * Usage:
+ * ```handlebars
+ *   {{count collection}}
+ * ```
+ *
+ * Arguments:
+ *  - "collection": an array or an instance of \Countable which elements should
+ *    be counted.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class CountHelper implements HelperInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function execute(Template $template, Context $context, $args, $source)
+    {
+        $parsed_args = $template->parseArguments($args);
+        if (count($parsed_args) != 1) {
+            throw new \InvalidArgumentException(
+                '"last" helper expects exactly one argument.'
+            );
+        }
+
+        $collection = $context->get($parsed_args[0]);
+        if (!is_array($collection) && !($collection instanceof \Countable)) {
+            throw new \InvalidArgumentException('Wrong type of the argument in the "count" helper.');
+        }
+
+        return count($collection);
+    }
+}

src/Collection/Helpers.php

@@ -26,6 +26,7 @@ class Helpers extends BaseHelpers
     {
         parent::addDefaultHelpers();
 
+        $this->add('count', new CountHelper());
         $this->add('first', new FirstHelper());
         $this->add('last', new LastHelper());
     }

src/Helpers.php

@@ -30,6 +30,7 @@ class Helpers extends BaseHelpers
         $this->add('formatDate', new Date\FormatDateHelper());
 
         // Collection helpers
+        $this->add('count', new Collection\CountHelper());
         $this->add('first', new Collection\FirstHelper());
         $this->add('last', new Collection\LastHelper());
 

tests/Collection/CountHelperTest.php

@@ -0,0 +1,111 @@
+<?php
+/*
+ * This file is part of Handlebars.php Helpers Set
+ *
+ * (c) Dmitriy Simushev <simushevds@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace JustBlackBird\HandlebarsHelpers\Tests\Collection;
+
+use JustBlackBird\HandlebarsHelpers\Collection\CountHelper;
+
+/**
+ * Test class for "count" helper.
+ *
+ * @author Dmitriy Simushev <simushevds@gmail.com>
+ */
+class CountHelperTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Tests that count is calculated properly.
+     *
+     * @dataProvider collectionsProvider
+     */
+    public function testCount($collection, $result)
+    {
+        $helpers = new \Handlebars\Helpers(array('count' => new CountHelper()));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $this->assertEquals(
+            $engine->render(
+                '{{count collection}}',
+                array('collection' => $collection)
+            ),
+            $result
+        );
+    }
+
+    /**
+     * A data provider for testCount method.
+     */
+    public function collectionsProvider()
+    {
+        return array(
+            // Test arrays with numeric keys
+            array(array('a', 'b', 'c'), '3'),
+            // Test associative arrays
+            array(array('a' => '10'), '1'),
+            // Test \Countable instance
+            array(new \ArrayIterator(array('a', 'b')), '2'),
+            // Test empty collections
+            array(array(), '0'),
+            array(new \ArrayIterator(array()), '0'),
+        );
+    }
+
+    /**
+     * Tests that exception is thrown if wrong number of arguments is used.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider wrongArgumentsCountProvider
+     */
+    public function testArgumentsCount($template)
+    {
+        $helpers = new \Handlebars\Helpers(array('count' => new CountHelper()));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render($template, array());
+    }
+
+    /**
+     * A data provider for testArgumentsCount method.
+     */
+    public function wrongArgumentsCountProvider()
+    {
+        return array(
+            // Not enough arguments
+            array('{{count}}'),
+            // Too much arguments
+            array('{{count "Arg" "ANOTHER ARG"}}'),
+        );
+    }
+
+    /**
+     * Tests invalid arguments type.
+     *
+     * @expectedException InvalidArgumentException
+     * @dataProvider invalidArgumentsProvider
+     */
+    public function testInvalidArguments($collection)
+    {
+        $helpers = new \Handlebars\Helpers(array('count' => new CountHelper()));
+        $engine = new \Handlebars\Handlebars(array('helpers' => $helpers));
+
+        $engine->render('{{count collection}}', array('collection' => $collection));
+    }
+
+    /**
+     * A data provider for testInvalidArguments method.
+     */
+    public function invalidArgumentsProvider()
+    {
+        return array(
+            array('a string'),
+            array(42),
+            array(new \stdClass()),
+        );
+    }
+}

tests/Collection/HelpersTest.php

@@ -38,6 +38,7 @@ class HelpersTest extends \PHPUnit_Framework_TestCase
     public function helpersProvider()
     {
         return array(
+            array('count', '\\JustBlackBird\\HandlebarsHelpers\\Collection\\CountHelper'),
             array('first', '\\JustBlackBird\\HandlebarsHelpers\\Collection\\FirstHelper'),
             array('last', '\\JustBlackBird\\HandlebarsHelpers\\Collection\\LastHelper'),
         );

tests/HelpersTest.php

@@ -42,6 +42,7 @@ class HelpersTest extends \PHPUnit_Framework_TestCase
             array('formatDate', '\\JustBlackBird\\HandlebarsHelpers\\Date\\FormatDateHelper'),
 
             // Collection helpers
+            array('count', '\\JustBlackBird\\HandlebarsHelpers\\Collection\\CountHelper'),
             array('first', '\\JustBlackBird\\HandlebarsHelpers\\Collection\\FirstHelper'),
             array('last', '\\JustBlackBird\\HandlebarsHelpers\\Collection\\LastHelper'),