diff -r 6d109e3804ac -r 9a001a04b634 Twig-1.3.0/lib/Twig/Extension/Core.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Twig-1.3.0/lib/Twig/Extension/Core.php	Tue Oct 25 23:56:28 2011 +0200
@@ -0,0 +1,847 @@
+<?php
+
+if (!defined('ENT_SUBSTITUTE')) {
+    define('ENT_SUBSTITUTE', 8);
+}
+
+/*
+ * This file is part of Twig.
+ *
+ * (c) 2009 Fabien Potencier
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+class Twig_Extension_Core extends Twig_Extension
+{
+    /**
+     * Returns the token parser instance to add to the existing list.
+     *
+     * @return array An array of Twig_TokenParser instances
+     */
+    public function getTokenParsers()
+    {
+        return array(
+            new Twig_TokenParser_For(),
+            new Twig_TokenParser_If(),
+            new Twig_TokenParser_Extends(),
+            new Twig_TokenParser_Include(),
+            new Twig_TokenParser_Block(),
+            new Twig_TokenParser_Use(),
+            new Twig_TokenParser_Filter(),
+            new Twig_TokenParser_Macro(),
+            new Twig_TokenParser_Import(),
+            new Twig_TokenParser_From(),
+            new Twig_TokenParser_Set(),
+            new Twig_TokenParser_Spaceless(),
+        );
+    }
+
+    /**
+     * Returns a list of filters to add to the existing list.
+     *
+     * @return array An array of filters
+     */
+    public function getFilters()
+    {
+        $filters = array(
+            // formatting filters
+            'date'    => new Twig_Filter_Function('twig_date_format_filter'),
+            'format'  => new Twig_Filter_Function('sprintf'),
+            'replace' => new Twig_Filter_Function('twig_strtr'),
+
+            // encoding
+            'url_encode'  => new Twig_Filter_Function('twig_urlencode_filter'),
+            'json_encode' => new Twig_Filter_Function('twig_jsonencode_filter'),
+
+            // string filters
+            'title'      => new Twig_Filter_Function('twig_title_string_filter', array('needs_environment' => true)),
+            'capitalize' => new Twig_Filter_Function('twig_capitalize_string_filter', array('needs_environment' => true)),
+            'upper'      => new Twig_Filter_Function('strtoupper'),
+            'lower'      => new Twig_Filter_Function('strtolower'),
+            'striptags'  => new Twig_Filter_Function('strip_tags'),
+
+            // array helpers
+            'join'    => new Twig_Filter_Function('twig_join_filter'),
+            'reverse' => new Twig_Filter_Function('twig_reverse_filter'),
+            'length'  => new Twig_Filter_Function('twig_length_filter', array('needs_environment' => true)),
+            'sort'    => new Twig_Filter_Function('twig_sort_filter'),
+            'merge'   => new Twig_Filter_Function('twig_array_merge'),
+
+            // iteration and runtime
+            'default' => new Twig_Filter_Function('twig_default_filter'),
+            'keys'    => new Twig_Filter_Function('twig_get_array_keys_filter'),
+
+            // escaping
+            'escape' => new Twig_Filter_Function('twig_escape_filter', array('needs_environment' => true, 'is_safe_callback' => 'twig_escape_filter_is_safe')),
+            'e'      => new Twig_Filter_Function('twig_escape_filter', array('needs_environment' => true, 'is_safe_callback' => 'twig_escape_filter_is_safe')),
+        );
+
+        if (function_exists('mb_get_info')) {
+            $filters['upper'] = new Twig_Filter_Function('twig_upper_filter', array('needs_environment' => true));
+            $filters['lower'] = new Twig_Filter_Function('twig_lower_filter', array('needs_environment' => true));
+        }
+
+        return $filters;
+    }
+
+    /**
+     * Returns a list of global functions to add to the existing list.
+     *
+     * @return array An array of global functions
+     */
+    public function getFunctions()
+    {
+        return array(
+            'range'    => new Twig_Function_Function('range'),
+            'constant' => new Twig_Function_Function('constant'),
+            'cycle'    => new Twig_Function_Function('twig_cycle'),
+        );
+    }
+
+    /**
+     * Returns a list of filters to add to the existing list.
+     *
+     * @return array An array of filters
+     */
+    public function getTests()
+    {
+        return array(
+            'even'        => new Twig_Test_Function('twig_test_even'),
+            'odd'         => new Twig_Test_Function('twig_test_odd'),
+            'defined'     => new Twig_Test_Function('twig_test_defined'),
+            'sameas'      => new Twig_Test_Function('twig_test_sameas'),
+            'none'        => new Twig_Test_Function('twig_test_none'),
+            'null'        => new Twig_Test_Function('twig_test_none'),
+            'divisibleby' => new Twig_Test_Function('twig_test_divisibleby'),
+            'constant'    => new Twig_Test_Function('twig_test_constant'),
+            'empty'       => new Twig_Test_Function('twig_test_empty'),
+        );
+    }
+
+    /**
+     * Returns a list of operators to add to the existing list.
+     *
+     * @return array An array of operators
+     */
+    public function getOperators()
+    {
+        return array(
+            array(
+                'not' => array('precedence' => 50, 'class' => 'Twig_Node_Expression_Unary_Not'),
+                '-'   => array('precedence' => 50, 'class' => 'Twig_Node_Expression_Unary_Neg'),
+                '+'   => array('precedence' => 50, 'class' => 'Twig_Node_Expression_Unary_Pos'),
+            ),
+            array(
+                'b-and'  => array('precedence' => 5, 'class' => 'Twig_Node_Expression_Binary_BitwiseAnd', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'b-xor'  => array('precedence' => 5, 'class' => 'Twig_Node_Expression_Binary_BitwiseXor', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'b-or'   => array('precedence' => 5, 'class' => 'Twig_Node_Expression_Binary_BitwiseOr', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'or'     => array('precedence' => 10, 'class' => 'Twig_Node_Expression_Binary_Or', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'and'    => array('precedence' => 15, 'class' => 'Twig_Node_Expression_Binary_And', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '=='     => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_Equal', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '!='     => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_NotEqual', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '<'      => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_Less', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '>'      => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_Greater', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '>='     => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_GreaterEqual', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '<='     => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_LessEqual', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'not in' => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_NotIn', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'in'     => array('precedence' => 20, 'class' => 'Twig_Node_Expression_Binary_In', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '+'      => array('precedence' => 30, 'class' => 'Twig_Node_Expression_Binary_Add', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '-'      => array('precedence' => 30, 'class' => 'Twig_Node_Expression_Binary_Sub', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '~'      => array('precedence' => 40, 'class' => 'Twig_Node_Expression_Binary_Concat', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '*'      => array('precedence' => 60, 'class' => 'Twig_Node_Expression_Binary_Mul', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '/'      => array('precedence' => 60, 'class' => 'Twig_Node_Expression_Binary_Div', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '//'     => array('precedence' => 60, 'class' => 'Twig_Node_Expression_Binary_FloorDiv', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '%'      => array('precedence' => 60, 'class' => 'Twig_Node_Expression_Binary_Mod', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'is'     => array('precedence' => 100, 'callable' => array($this, 'parseTestExpression'), 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                'is not' => array('precedence' => 100, 'callable' => array($this, 'parseNotTestExpression'), 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '..'     => array('precedence' => 110, 'class' => 'Twig_Node_Expression_Binary_Range', 'associativity' => Twig_ExpressionParser::OPERATOR_LEFT),
+                '**'     => array('precedence' => 200, 'class' => 'Twig_Node_Expression_Binary_Power', 'associativity' => Twig_ExpressionParser::OPERATOR_RIGHT),
+            ),
+        );
+    }
+
+    public function parseNotTestExpression(Twig_Parser $parser, $node)
+    {
+        return new Twig_Node_Expression_Unary_Not($this->parseTestExpression($parser, $node), $parser->getCurrentToken()->getLine());
+    }
+
+    public function parseTestExpression(Twig_Parser $parser, $node)
+    {
+        $stream = $parser->getStream();
+        $name = $stream->expect(Twig_Token::NAME_TYPE);
+        $arguments = null;
+        if ($stream->test(Twig_Token::PUNCTUATION_TYPE, '(')) {
+            $arguments = $parser->getExpressionParser()->parseArguments();
+        }
+
+        return new Twig_Node_Expression_Test($node, $name->getValue(), $arguments, $parser->getCurrentToken()->getLine());
+    }
+
+    /**
+     * Returns the name of the extension.
+     *
+     * @return string The extension name
+     */
+    public function getName()
+    {
+        return 'core';
+    }
+}
+
+/**
+ * Cycles over a value.
+ *
+ * @param ArrayAccess|array $values An array or an ArrayAccess instance
+ * @param integer           $i      The cycle value
+ *
+ * @return string The next value in the cycle
+ */
+function twig_cycle($values, $i)
+{
+    if (!is_array($values) && !$values instanceof ArrayAccess) {
+        return $values;
+    }
+
+    return $values[$i % count($values)];
+}
+
+/**
+ * Converts a date to the given format.
+ *
+ * <pre>
+ *   {{ post.published_at|date("m/d/Y") }}
+ * </pre>
+ *
+ * @param DateTime|string     $date     A date
+ * @param string              $format   A format
+ * @param DateTimeZone|string $timezone A timezone
+ *
+ * @return string The formatter date
+ */
+function twig_date_format_filter($date, $format = 'F j, Y H:i', $timezone = null)
+{
+    if (!$date instanceof DateTime && !$date instanceof DateInterval) {
+        if (ctype_digit((string) $date)) {
+            $date = new DateTime('@'.$date);
+            $date->setTimezone(new DateTimeZone(date_default_timezone_get()));
+        } else {
+            $date = new DateTime($date);
+        }
+    }
+
+    if (null !== $timezone) {
+        if (!$timezone instanceof DateTimeZone) {
+            $timezone = new DateTimeZone($timezone);
+        }
+
+        $date->setTimezone($timezone);
+    }
+
+    return $date->format($format);
+}
+
+/**
+ * URL encodes a string.
+ *
+ * @param string $url A URL
+ * @param bool   $raw true to use rawurlencode() instead of urlencode
+ *
+ * @return string The URL encoded value
+ */
+function twig_urlencode_filter($url, $raw = false)
+{
+    if ($raw) {
+        return rawurlencode($url);
+    }
+
+    return urlencode($url);
+}
+
+if (version_compare(PHP_VERSION, '5.3.0', '<')) {
+    /**
+     * JSON encodes a PHP variable.
+     *
+     * @param mixed   $value   The value to encode.
+     * @param integer $options Not used on PHP 5.2.x
+     *
+     * @return mixed The JSON encoded value
+     */
+    function twig_jsonencode_filter($value, $options = 0)
+    {
+        if ($value instanceof Twig_Markup) {
+            $value = (string) $value;
+        } elseif (is_array($value)) {
+            array_walk_recursive($value, '_twig_markup2string');
+        }
+
+        return json_encode($value);
+    }
+} else {
+    /**
+     * JSON encodes a PHP variable.
+     *
+     * @param mixed   $value   The value to encode.
+     * @param integer $options Bitmask consisting of JSON_HEX_QUOT, JSON_HEX_TAG, JSON_HEX_AMP, JSON_HEX_APOS, JSON_NUMERIC_CHECK, JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, JSON_FORCE_OBJECT
+     *
+     * @return mixed The JSON encoded value
+     */
+    function twig_jsonencode_filter($value, $options = 0)
+    {
+        if ($value instanceof Twig_Markup) {
+            $value = (string) $value;
+        } elseif (is_array($value)) {
+            array_walk_recursive($value, '_twig_markup2string');
+        }
+
+        return json_encode($value, $options);
+    }
+}
+
+function _twig_markup2string(&$value)
+{
+    if ($value instanceof Twig_Markup) {
+        $value = (string) $value;
+    }
+}
+
+/**
+ * Merges an array with another one.
+ *
+ * <pre>
+ *  {% set items = { 'apple': 'fruit', 'orange': 'fruit' } %}
+ *
+ *  {% set items = items|merge({ 'peugeot': 'car' }) %}
+ *
+ *  {# items now contains { 'apple': 'fruit', 'orange': 'fruit', 'peugeot': 'car' } #}
+ * </pre>
+ *
+ * @param array $arr1 An array
+ * @param array $arr2 An array
+ *
+ * @return array The merged array
+ */
+function twig_array_merge($arr1, $arr2)
+{
+    if (!is_array($arr1) || !is_array($arr2)) {
+        throw new Twig_Error_Runtime('The merge filter only work with arrays or hashes.');
+    }
+
+    return array_merge($arr1, $arr2);
+}
+
+/**
+ * Joins the values to a string.
+ *
+ * The separator between elements is an empty string per default, you can define it with the optional parameter.
+ *
+ * <pre>
+ *  {{ [1, 2, 3]|join('|') }}
+ *  {# returns 1|2|3 #}
+ *
+ *  {{ [1, 2, 3]|join }}
+ *  {# returns 123 #}
+ * </pre>
+ *
+ * @param array  $value An array
+ * @param string $glue  The separator
+ *
+ * @return string The concatenated string
+ */
+function twig_join_filter($value, $glue = '')
+{
+    return implode($glue, (array) $value);
+}
+
+/**
+ * Returns the value or the default value when it is undefined or empty.
+ *
+ * <pre>
+ *
+ *  {{ var.foo|default('foo item on var is not defined') }}
+ *
+ * </pre>
+ *
+ * @param mixed $value   A value
+ * @param mixed $default The default value
+ *
+ * @param mixed The value or the default value;
+ */
+function twig_default_filter($value, $default = '')
+{
+    if (twig_test_empty($value)) {
+        return $default;
+    } else {
+        return $value;
+    }
+}
+
+/**
+ * Returns the keys for the given array.
+ *
+ * It is useful when you want to iterate over the keys of an array:
+ *
+ * <pre>
+ *  {% for key in array|keys %}
+ *      {# ... #}
+ *  {% endfor %}
+ * </pre>
+ *
+ * @param array $array An array
+ *
+ * @return array The keys
+ */
+function twig_get_array_keys_filter($array)
+{
+    if (is_object($array) && $array instanceof Traversable) {
+        return array_keys(iterator_to_array($array));
+    }
+
+    if (!is_array($array)) {
+        return array();
+    }
+
+    return array_keys($array);
+}
+
+/**
+ * Reverses an array.
+ *
+ * @param array|Traversable $array An array or a Traversable instance
+ *
+ * return array The array reversed
+ */
+function twig_reverse_filter($array)
+{
+    if (is_object($array) && $array instanceof Traversable) {
+        return array_reverse(iterator_to_array($array));
+    }
+
+    if (!is_array($array)) {
+        return array();
+    }
+
+    return array_reverse($array);
+}
+
+/**
+ * Sorts an array.
+ *
+ * @param array $array An array
+ */
+function twig_sort_filter($array)
+{
+    asort($array);
+
+    return $array;
+}
+
+/* used internally */
+function twig_in_filter($value, $compare)
+{
+    if (is_array($compare)) {
+        return in_array($value, $compare);
+    } elseif (is_string($compare)) {
+        return false !== strpos($compare, (string) $value);
+    } elseif (is_object($compare) && $compare instanceof Traversable) {
+        return in_array($value, iterator_to_array($compare, false));
+    }
+
+    return false;
+}
+
+/**
+ * Replaces placeholders in a string.
+ *
+ * <pre>
+ *  {{ "I like %this% and %that%."|replace({'%this%': foo, '%that%': "bar"}) }}
+ * </pre>
+ *
+ * @param string $pattern      A string
+ * @param string $replacements The values for the placeholders
+ *
+ * @return string The string where the placeholders have been replaced
+ */
+function twig_strtr($pattern, $replacements)
+{
+    return str_replace(array_keys($replacements), array_values($replacements), $pattern);
+}
+
+/**
+ * Escapes a string.
+ *
+ * @param Twig_Environment $env        A Twig_Environment instance
+ * @param string           $string     The value to be escaped
+ * @param string           $type       The escaping strategy
+ * @param string           $charset    The charset
+ * @param Boolean          $autoescape Whether the function is called by the auto-escaping feature (true) or by the developer (false)
+ */
+function twig_escape_filter(Twig_Environment $env, $string, $type = 'html', $charset = null, $autoescape = false)
+{
+    if ($autoescape && is_object($string) && $string instanceof Twig_Markup) {
+        return $string;
+    }
+
+    if (!is_string($string) && !(is_object($string) && method_exists($string, '__toString'))) {
+        return $string;
+    }
+
+    if (null === $charset) {
+        $charset = $env->getCharset();
+    }
+
+    switch ($type) {
+        case 'js':
+            // escape all non-alphanumeric characters
+            // into their \xHH or \uHHHH representations
+            if ('UTF-8' != $charset) {
+                $string = _twig_convert_encoding($string, 'UTF-8', $charset);
+            }
+
+            if (null === $string = preg_replace_callback('#[^\p{L}\p{N} ]#u', '_twig_escape_js_callback', $string)) {
+                throw new Twig_Error_Runtime('The string to escape is not a valid UTF-8 string.');
+            }
+
+            if ('UTF-8' != $charset) {
+                $string = _twig_convert_encoding($string, $charset, 'UTF-8');
+            }
+
+            return $string;
+
+        case 'html':
+            return htmlspecialchars($string, ENT_QUOTES | ENT_SUBSTITUTE, $charset);
+
+        default:
+            throw new Twig_Error_Runtime(sprintf('Invalid escape type "%s".', $type));
+    }
+}
+
+/* used internally */
+function twig_escape_filter_is_safe(Twig_Node $filterArgs)
+{
+    foreach ($filterArgs as $arg) {
+        if ($arg instanceof Twig_Node_Expression_Constant) {
+            return array($arg->getAttribute('value'));
+        } else {
+            return array();
+        }
+
+        break;
+    }
+
+    return array('html');
+}
+
+if (function_exists('iconv')) {
+    function _twig_convert_encoding($string, $to, $from)
+    {
+        return iconv($from, $to, $string);
+    }
+} elseif (function_exists('mb_convert_encoding')) {
+    function _twig_convert_encoding($string, $to, $from)
+    {
+        return mb_convert_encoding($string, $to, $from);
+    }
+} else {
+    function _twig_convert_encoding($string, $to, $from)
+    {
+        throw new Twig_Error_Runtime('No suitable convert encoding function (use UTF-8 as your encoding or install the iconv or mbstring extension).');
+    }
+}
+
+function _twig_escape_js_callback($matches)
+{
+    $char = $matches[0];
+
+    // \xHH
+    if (!isset($char[1])) {
+        return '\\x'.substr('00'.bin2hex($char), -2);
+    }
+
+    // \uHHHH
+    $char = _twig_convert_encoding($char, 'UTF-16BE', 'UTF-8');
+
+    return '\\u'.substr('0000'.bin2hex($char), -4);
+}
+
+// add multibyte extensions if possible
+if (function_exists('mb_get_info')) {
+    /**
+     * Returns the length of a PHP variable.
+     *
+     * @param Twig_Environment $env   A Twig_Environment instance
+     * @param mixed            $thing A PHP variable
+     *
+     * @return integer The length of the value
+     */
+    function twig_length_filter(Twig_Environment $env, $thing)
+    {
+        return is_scalar($thing) ? mb_strlen($thing, $env->getCharset()) : count($thing);
+    }
+
+    /**
+     * Converts a string to uppercase.
+     *
+     * @param Twig_Environment $env    A Twig_Environment instance
+     * @param string           $string A string
+     *
+     * @return string The uppercased string
+     */
+    function twig_upper_filter(Twig_Environment $env, $string)
+    {
+        if (null !== ($charset = $env->getCharset())) {
+            return mb_strtoupper($string, $charset);
+        }
+
+        return strtoupper($string);
+    }
+
+    /**
+     * Converts a string to lowercase.
+     *
+     * @param Twig_Environment $env    A Twig_Environment instance
+     * @param string           $string A string
+     *
+     * @return string The lowercased string
+     */
+    function twig_lower_filter(Twig_Environment $env, $string)
+    {
+        if (null !== ($charset = $env->getCharset())) {
+            return mb_strtolower($string, $charset);
+        }
+
+        return strtolower($string);
+    }
+
+    /**
+     * Returns a titlecased string.
+     *
+     * @param Twig_Environment $env    A Twig_Environment instance
+     * @param string           $string A string
+     *
+     * @return string The titlecased string
+     */
+    function twig_title_string_filter(Twig_Environment $env, $string)
+    {
+        if (null !== ($charset = $env->getCharset())) {
+            return mb_convert_case($string, MB_CASE_TITLE, $charset);
+        }
+
+        return ucwords(strtolower($string));
+    }
+
+    /**
+     * Returns a capitalized string.
+     *
+     * @param Twig_Environment $env    A Twig_Environment instance
+     * @param string           $string A string
+     *
+     * @return string The capitalized string
+     */
+    function twig_capitalize_string_filter(Twig_Environment $env, $string)
+    {
+        if (null !== ($charset = $env->getCharset())) {
+            return mb_strtoupper(mb_substr($string, 0, 1, $charset), $charset).
+                         mb_strtolower(mb_substr($string, 1, mb_strlen($string, $charset), $charset), $charset);
+        }
+
+        return ucfirst(strtolower($string));
+    }
+}
+// and byte fallback
+else
+{
+    /**
+     * Returns the length of a PHP variable.
+     *
+     * @param Twig_Environment $env   A Twig_Environment instance
+     * @param mixed            $thing A PHP variable
+     *
+     * @return integer The length of the value
+     */
+    function twig_length_filter(Twig_Environment $env, $thing)
+    {
+        return is_scalar($thing) ? strlen($thing) : count($thing);
+    }
+
+    /**
+     * Returns a titlecased string.
+     *
+     * @param Twig_Environment $env    A Twig_Environment instance
+     * @param string           $string A string
+     *
+     * @return string The titlecased string
+     */
+    function twig_title_string_filter(Twig_Environment $env, $string)
+    {
+        return ucwords(strtolower($string));
+    }
+
+    /**
+     * Returns a capitalized string.
+     *
+     * @param Twig_Environment $env    A Twig_Environment instance
+     * @param string           $string A string
+     *
+     * @return string The capitalized string
+     */
+    function twig_capitalize_string_filter(Twig_Environment $env, $string)
+    {
+        return ucfirst(strtolower($string));
+    }
+}
+
+/* used internally */
+function twig_ensure_traversable($seq)
+{
+    if (is_array($seq) || (is_object($seq) && $seq instanceof Traversable)) {
+        return $seq;
+    } else {
+        return array();
+    }
+}
+
+/**
+ * Checks that a variable points to the same memory address than another one.
+ *
+ * <pre>
+ * {% if foo.attribute is sameas(false) %}
+ *    the foo attribute really is the ``false`` PHP value
+ * {% endif %}
+ * </pre>
+ *
+ * @param mixed $value A PHP variable
+ * @param mixed $test  The PHP variable to test against
+ *
+ * @return Boolean true if the values are the same, false otherwise
+ */
+function twig_test_sameas($value, $test)
+{
+    return $value === $test;
+}
+
+/**
+ * Checks that a variable is null.
+ *
+ * <pre>
+ *  {{ var is none }}
+ * </pre>
+ *
+ * @param mixed $value a PHP variable.
+ *
+ * @return Boolean true if the value is null, false otherwise
+ */
+function twig_test_none($value)
+{
+    return null === $value;
+}
+
+/**
+ * Checks if a variable is divisible by a number.
+ *
+ * <pre>
+ *  {% if loop.index is divisibleby(3) %}
+ * </pre>
+ *
+ * @param integer $value A PHP value
+ * @param integer $num   A number
+ *
+ * @return Boolean true if the value is divisible by the number, false otherwise
+ */
+function twig_test_divisibleby($value, $num)
+{
+    return 0 == $value % $num;
+}
+
+/**
+ * Checks if a number is even.
+ *
+ * <pre>
+ *  {{ var is even }}
+ * </pre>
+ *
+ * @param integer $value An integer
+ *
+ * @return Boolean true if the value is even, false otherwise
+ */
+function twig_test_even($value)
+{
+    return $value % 2 == 0;
+}
+
+/**
+ * Checks if a number is odd.
+ *
+ * <pre>
+ *  {{ var is odd }}
+ * </pre>
+ *
+ * @param integer $value An integer
+ *
+ * @return Boolean true if the value is odd, false otherwise
+ */
+function twig_test_odd($value)
+{
+    return $value % 2 == 1;
+}
+
+/**
+ * Checks if a variable is the exact same value as a constant.
+ *
+ * <pre>
+ *  {% if post.status is constant('Post::PUBLISHED') %}
+ *    the status attribute is exactly the same as Post::PUBLISHED
+ *  {% endif %}
+ * </pre>
+ *
+ * @param mixed $value    A PHP value
+ * @param mixed $constant The constant to test against
+ *
+ * @return Boolean true if the value is the same as the constant, false otherwise
+ */
+function twig_test_constant($value, $constant)
+{
+    return constant($constant) === $value;
+}
+
+/**
+ * Checks if a variable is defined in the current context.
+ *
+ * <pre>
+ * {# defined works with variable names #}
+ * {% if foo is defined %}
+ *     {# ... #}
+ * {% endif %}
+ * </pre>
+ *
+ * @param mixed $name    A PHP variable
+ * @param array $context The current context
+ *
+ * @return Boolean true if the value is defined, false otherwise
+ */
+function twig_test_defined($name, $context)
+{
+    return array_key_exists($name, $context);
+}
+
+/**
+ * Checks if a variable is empty.
+ *
+ * <pre>
+ * {# evaluates to true if the foo variable is null, false, or the empty string #}
+ * {% if foo is empty %}
+ *     {# ... #}
+ * {% endif %}
+ * </pre>
+ *
+ * @param mixed $value A PHP variable
+ *
+ * @return Boolean true if the value is empty, false otherwise
+ */
+function twig_test_empty($value)
+{
+    if ($value instanceof Countable) {
+        return 0 == count($value);
+    }
+    return false === $value || (empty($value) && '0' != $value);
+}