svg_path_parser.js

/* 
   Path parser by Devon Govett
   Input: String path
   Returns: Array of objects with command and arguments
*/

//Number of allowed parameters for each command
var parameters = {
        A: 7,
        a: 7,
        C: 6,
        c: 6,
        H: 1,
        h: 1,
        L: 2,
        l: 2,
        M: 2,
        m: 2,
        Q: 4,
        q: 4,
        S: 4,
        s: 4,
        T: 2,
        t: 2,
        V: 1,
        v: 1,
        Z: 0,
        z: 0
};

/* PARSE THE PATH */
var ret = [], cmd, args = [], curArg = "", found_decimal = false, undefined;
for(var i = 0, len = path.length; i < len; i++) {
	var c = path[i];
	if(parameters[c] != undefined) {
		if(cmd) { //Save existing command
			if(curArg.length > 0) args[args.length] = +curArg;
			ret[ret.length] = { command: cmd, args: args };
			args = [], curArg = "", found_decimal = false;
		}
		cmd = c;
	}
	else if(c == " " || c == "," ||  (c == "-" && curArg.length > 0) || (c == "." && found_decimal)) {
		if(curArg.length == 0) continue;
		
		if(args.length == parameters[cmd]) { //Handle reused commands
			ret[ret.length] = { command: cmd, args: args };
			args = [+curArg];
			
			//handle assumed commands
			if(cmd == "M") cmd = "L";
			else if(cmd == "m") cmd = "l";
		}
		else {
			args[args.length] = +curArg;
		}
		
		found_decimal = (c == ".");
		curArg = (c == "-" ? "-" : c == "." ? "." : ""); //fix for negative numbers or repeated decimals with no delimeter between commands
	}
	else {
		curArg += c;
		if(c == ".") found_decimal = true; //cache instead of using indexOf
	}
}
//Add the last command
if(curArg.length > 0) args[args.length] = +curArg;
ret[ret.length] = { command: cmd, args: args };