color.cpp

#define HEXCHAR2INT(x, y)  ((x >= 'a' ? x-87 : x-48) * 16 + (y >= 'a' ? y-87 : y-48))

float * _parse_color(const char * str){
    int size = strlen(str);
	float * ret = new float[4];
	
	switch(size){
		case 4: // #rgb
			ret[0] = HEXCHAR2INT(str[1], str[1]) / 255.0;
			ret[1] = HEXCHAR2INT(str[2], str[2]) / 255.0;
			ret[2] = HEXCHAR2INT(str[3], str[3]) / 255.0;
			ret[3] = 1.0;
			break;
			
		case 5: // #rgba
			ret[0] = HEXCHAR2INT(str[1], str[1]) / 255.0;
			ret[1] = HEXCHAR2INT(str[2], str[2]) / 255.0;
			ret[2] = HEXCHAR2INT(str[3], str[3]) / 255.0;
			ret[3] = HEXCHAR2INT(str[4], str[4]) / 255.0;
			break;
			
		case 7: // #rrggbb
			ret[0] = HEXCHAR2INT(str[1], str[2]) / 255.0;
			ret[1] = HEXCHAR2INT(str[3], str[4]) / 255.0;
			ret[2] = HEXCHAR2INT(str[5], str[6]) / 255.0;
			ret[3] = 1.0;
			break;
			
		case 9:	// #rrggbbaa
			ret[0] = HEXCHAR2INT(str[1], str[2]) / 255.0;
			ret[1] = HEXCHAR2INT(str[3], str[4]) / 255.0;
			ret[2] = HEXCHAR2INT(str[5], str[6]) / 255.0;
			ret[3] = HEXCHAR2INT(str[7], str[8]) / 255.0;
			break;
			
	}
    return ret;
}

color.scala

import scala.util.matching.Regex

def color(name: String) = {
	val RGB 	= """#([a-f0-9])([a-f0-9])([a-f0-9])""".r
	val RGBA 	= """#([a-f0-9])([a-f0-9])([a-f0-9])([a-f0-9])""".r
	val RRGGBB 	= """#([a-f0-9]{2})([a-f0-9]{2})([a-f0-9]{2})""".r
	val RRGGBBAA = """#([a-f0-9]{2})([a-f0-9]{2})([a-f0-9]{2})([a-f0-9]{2})""".r
	
	def s(s: String) = {
		val x = Integer.parseInt(s, 16)
		(x*16 + x) / 255.0
	}
	def p(s: String) = Integer.parseInt(s, 16) / 255.0
	
	name match {
		case RGB(r,g,b) => List(r,g,b).map(s)
		case RGBA(r,g,b,a) => List(r,g,b,a).map(s)
		case RRGGBB(r,g,b) => List(r,g,b).map(p)
		case RRGGBBAA(r,g,b,a) => List(r,g,b,a).map(p)
		case _ => println("Cannot parse color: " + name)
	}
}

val xs = List("#100", "#f905", "#ff000011", "#ff99cc")
println(xs)
println(xs.map(color(_)))