}
        }

        return $response;
    }

    /**
     * Extend tree with additional statements and params
     *
     * @param array $addition
     *
     * @return array
     *
     * @since 6.5.3 https://github.com/aamplugin/advanced-access-manager/issues/122
     *              https://github.com/aamplugin/advanced-access-manager/issues/124
     * @since 6.4.1 Simplified by removing &$tree first param
     * @since 6.4.0 Supporting Param's Value to be more than just a scalar value
     * @since 6.2.1 Typecasting param's value
     * @since 6.1.0 Added support for the `=>` (map to) operator
     * @since 6.0.0 Initial implementation of the method
     *
     * @access protected
     * @version 6.5.3
     */
    protected function updatePolicyTree($addition)
    {
        $stmts  = &$this->tree['Statement'];
        $params = &$this->tree['Param'];

        $callback = array($this, 'getOption'); // Callback that hooks into get_option

        // Step #1. If there are any params, let's index them and insert into the list
        foreach ($addition['Param'] as $param) {
            if (!empty($param['Key'])) {
                $param['Value'] = $this->replaceTokens($param['Value'], true);

                foreach($this->evaluatePolicyKey($param['Key']) as $key) {
                    if (!isset($params[$key]) || empty($params[$key]['Enforce'])) {
                        $params[$key] = $param;

                        // If "option:" - hooks to the WP core for override
                        if (strpos($key, 'option:') === 0) {
                            $name = substr($key, 7);

                            // Hook into the core
                            add_filter('pre_option_' . $name, $callback, 1, 2);
                            add_filter('pre_site_option_' . $name, $callback, 1, 2);
                        }
                    }
                }
            }
        }

        // Step #2. If there are any statements, let's index them by resource:action
        // and insert into the list of statements
        foreach ($addition['Statement'] as $stm) {
            $resources = (isset($stm['Resource']) ? (array) $stm['Resource'] : array());
            $actions   = (isset($stm['Action']) ? (array) $stm['Action'] : array(''));

            foreach ($resources as $res) {
                foreach($this->evaluatePolicyKey($res) as $resource) {
                    foreach ($actions as $act) {
                        $id = strtolower($resource . (!empty($act) ? ":{$act}" : ''));

                        if (isset($stmts[$id])) {
                            if (isset($stmts[$id][0])) {
                                $stmts[$id][] = $stm;
                            } else {
                                $stmts[$id] = array($stmts[$id], $stm);
                            }
                        } else {
                            $stmts[$id] = $stm;
                        }
                    }
                }
            }
        }
    }

    /**
     * Evaluate resource name or param key
     *
     * The resource or param key may have tokens that build dynamic keys. This method
     * covers 3 possible scenario:
     * - Map To "=>" - the token should return array of values that are mapped to the
     *                 key;
     * - Token       - returns scalar value;
     * - Raw Value   - returns as-is
     *
     * @param string $key
     *
     * @return array
     *
     * @access protected
     * @version 6.4.1
     */
    protected function evaluatePolicyKey($key)
    {
        $response = array();

        // Allow to build resource name or param key dynamically.
        if (preg_match('/^(.*)[\s]+(map to|=>)[\s]+(.*)$/i', $key, $match)) {

            // e.g. "Term:category:%s:posts => ${USER_META.regions}"
            // e.g. "%s:default:category => ${HTTP_POST.post_types}"
            $values = (array) AAM_Core_Policy_Token::getTokenValue($match[3]);

            // Create the map of resources/params and replace
            foreach($values as $value) {
                $response[] = sprintf($match[1], $value);
            }
        } elseif (preg_match_all('/(\$\{[^}]+\})/', $key, $match)) {
            // e.g. "Term:category:${USER_META.region}:posts"
            $response = array(AAM_Core_Policy_Token::evaluate($key, $match[1]));
        } else {
            $response = array($key);
        }

        return $response;
    }

    /**
     * Replace all the dynamic tokens recursively
     *
     * @param array   $data
     * @param boolean $type_cast
     *
     * @return array
     *
     * @since 6.4.1 Added type casting param
     * @since 6.0.0 Initial implementation of the method
     *
     * @access protected
     * @version 6.4.1
     */
    protected function replaceTokens($data, $type_cast = false)
    {
        $replaced = array();

        if (is_scalar($data)) {
            $replaced = $this->_replaceTokensInString($data, $type_cast);
        } else {
            foreach($data as $key => $value) {
                // Evaluate array's key and replace tokens
                $key = $this->_replaceTokensInString($key);

                // Evaluate array's value and replace tokens
                if (is_array($value)) {
                    $replaced[$key] = $this->replaceTokens($value, $type_cast);
                } else {
                    $replaced[$key] = $this->_replaceTokensInString(
                        $value, $type_cast
                    );
                }
            }
        }

        return $replaced;
    }

    /**
     * Replace tokens is provided scalar string
     *
     * @param string  $token
     * @param boolean $type_cast
     *
     * @return mixed
     *
     * @access private
     * @version 6.4.1
     */
    private function _replaceTokensInString($token, $type_cast = false)
    {
        if (preg_match_all('/(\$\{[^}]+\})/', $token, $match)) {
            $value = AAM_Core_Policy_Token::evaluate($token, $match[1]);

            if ($type_cast === true) {
                $replaced = AAM_Core_Policy_Typecast::execute($value);
            } else {
                $replaced = $value;
            }
        } else {
            $replaced = $token;
        }

        return  $replaced;
    }

    /**
     * Perform some internal clean-up
     *
     * @param array &$statements
     *
     * @return void
     *
     * @since 6.5.3 https://github.com/aamplugin/advanced-access-manager/issues/124
     * @since 6.0.0 Initial implementation of the method
     *
     * @access private
     * @version 6.5.3
     */
    private function _cleanupTree(&$statements)
    {
        foreach($statements as $id => &$stm) {
            if (is_array($stm) && isset($stm[0])) {
                $this->_cleanupTree($stm);
            } else {
                if (isset($stm['Resource'])) {
                    unset($statements[$id]['Resource']);
                }
                if (isset($stm['Action'])) {
                    unset($statements[$id]['Action']);
                }
            }
        }
    }

    /**
     * Check if policy block is applicable
     *
     * @param array $block
     * @param array $args
     *
     * @return boolean
     *
     * @access protected
     * @version 6.0.0
     */
    protected function isApplicable($block, $args = array())
    {
        $result = true;

        if (!empty($block['Condition']) && is_array($block['Condition'])) {
            $result = AAM_Core_Policy_Condition::getInstance()->evaluate(
                $block['Condition'], $args
            );
        }

        return $result;
    }

}