func_get_args extended to include default parameters

func_get_args_with_defaults.php

if (!function_exists('func_get_args_with_defaults')) {
    /**
     * Get all function arguments, including defaults.
     * An issue with func_get_args is that it doesn't include default
     * values. This leads to cases where we'd expect cache re-use, but are
     * seeing cache misses, e.g:
     * $foo->getStuff('category');
     * $foo->getStuff('category', 1, 100);
     *
     * function getStuff($type, $page = 1, $limit = 100)
     *
     * Using func_get_args to generate a cache key here will generate a different
     * key on each call, despite the values of $page and $limit being the same.
     * This function uses reflection to work out the full param list.
     *
     * Usage:
     * $args = func_get_args_with_defaults([$this, __FUNCTION__], func_get_args());
     */
    function func_get_args_with_defaults(callable $fn, $data = []) : array
    {
        if (is_string($fn) || $fn instanceof \Closure) {
            $reflection = new \ReflectionFunction($fn);
        } elseif (is_array($fn)) {
            if (is_object($fn[0])) {
                $class = new \ReflectionObject($fn[0]);
            } else {
                // assume string
                $class = new \ReflectionClass($fn[0]);
            }
            $reflection = $class->getMethod($fn[1]);
        }

        $args = [];
        foreach ($reflection->getParameters() as $i => $parameter) {
            $name = $parameter->getName();
            if (isset($data[$i])) {
                $args[$name] = $data[$i];
            } else {
                $args[$name] = $parameter->isDefaultValueAvailable() ?
                    $parameter->getDefaultValue() : null;
            }
        }

        return $args;
    }
}