AS3 Custom string formula parser - actionscript-3

Question

My goal is to create some kind of Parser to parse string formulas, similar to Excel formulas.
Formula string example (barcode example) -
"CONCAT('98', ZEROFILL([productNumber],5,'0'), ZEROFILL(EQUATION([weightKG]*1000),5,'0'))"
where
'98' - String
[productNumber] and [weightKG] - are variables that can be changed
CONCAT, ZEROFILL and EQUATION are methods which exist in class
For this formula with variables [productNumber] = '1' and [weightKG] = 0.1 result must be
'980000100100'
The question is how to split/parse whole string to parts and detect methods, variables and string values?
Another idea occurred, while i was typing - is to store whole formula in XML format.
Thank You.

Answer 1

You can use String.split() to get an array of substrings.
However, using your example, calling split(",") would give you the following array:
[0]=CONCAT('98'
[1]= ZEROFILL([productNumber]
[2]=5
[3]='0')
[4]= ZEROFILL(EQUATION([weightKG]*1000)
[5]=5
[6]='0'))
That doesn't seem like it will be very helpful for your project. Instead, you might think about creating a parse() function with some logic to find useful substrings:
function parse(input:String):Array {
var firstParen:int = input.indexOf("(");
var lastParen:int = input.lastIndexOf(")");
var formulaName:String = input.substring(0, firstParen);
var arguments:String = input.substring(firstParen, lastParen);
var argumentList:Array = parseArgs(arguments);
var result:Array = new Array();
result.push(formulaName);
//Recursively call parse() on the argumentList
foreach (var elem:* in argumentList) {
result.push(elem); //Could be string or array.
}
}
function parseArgs(input:String):Array {
// Look for commas that aren't enclosed inside parenthesis and
// construct an array of substrings based on that.
//A regex may be helpful here, but the implementation is left
//as an exercise for the reader.
}