oval-branch-4643

readme.md

oval-branch-4643

Created with <3 with dartpad.dev.

main.dart

num evaluate(String expr) {
  var divAndMult =
      RegExp(r"\(?\s*(\d+(?:\.\d*)?)\s*([/*])\s*(\d+(?:\.\d*)?)\s*\)?");
  var addAndSub =
      RegExp(r"\(?\s*(\d+(?:\.\d*)?)\s*([+-])\s*(\d+(?:\.\d*)?)\s*\)?");
  
  var nextInput = expr;

  while (divAndMult.hasMatch(nextInput) || addAndSub.hasMatch(nextInput)) {
    var first = nextInput.replaceAllMapped(divAndMult, (match) {
      if (match[2] == "*") {
        return (num.parse(match[1]!) * num.parse(match[3]!)).toString();
      }
      return (num.parse(match[1]!) / num.parse(match[3]!)).toString();
    });

    nextInput = first.replaceAllMapped(addAndSub, (match) {
      if (match[2] == "+") {
        return (num.parse(match[1]!) + num.parse(match[3]!)).toString();
      }
      return (num.parse(match[1]!) - num.parse(match[3]!)).toString();
    });
  }

  return num.parse(nextInput);
}

void main() {
  print(evaluate("(8 * 8) - (20 / 5) + 8"));
  print(evaluate("( 2 + 12 )"));
  print(evaluate("100 * ( 2 + 12 ) / 14"));
  print(evaluate("10.5 + 2 * 6"));
}