protected function coerceValue($value)
    {
        if (is_array($value) || $value instanceof \ArrayAccess) {
            return $value;
        }

        if (is_bool($value)) {
            return $this->toBool($value);
        }

        if ($value === null) {
            return static::$null;
        }

        if (is_numeric($value)) {
            return new Node\Number($value, '');
        }

        if ($value === '') {
            return static::$emptyString;
        }

        if (preg_match('/^(#([0-9a-f]{6})|#([0-9a-f]{3}))$/i', $value, $m)) {
            $color = [Type::T_COLOR];

            if (isset($m[3])) {
                $num = hexdec($m[3]);

                foreach ([3, 2, 1] as $i) {
                    $t = $num & 0xf;
                    $color[$i] = $t << 4 | $t;
                    $num >>= 4;
                }
            } else {
                $num = hexdec($m[2]);

                foreach ([3, 2, 1] as $i) {
                    $color[$i] = $num & 0xff;
                    $num >>= 8;
                }
            }

            return $color;
        }

        return [Type::T_KEYWORD, $value];
    }