Parse CSS colors in Kotlin

color.kt

class Color(val red: Int, val green: Int, val blue: Int, val alpha: Float) {

    companion object {

        private val pattern = Pattern.compile("^rgba?\\((\\d+), (\\d+), (\\d+)(?:, ([\\d.]+))?\\)$")

        fun fromString(string: String): Color? {
            val matcher = pattern.matcher(string)

            if (!matcher.matches()) return null

            val red = matcher.group(1).toInt()
            val green = matcher.group(2).toInt()
            val blue = matcher.group(3).toInt()
            val alpha = matcher.group(4)?.toFloat() ?: 1.0f
                
            return Color(red, green, blue, alpha)
        }
    }
}