Parameter info

main.dart

String test = "print(print(as<caret>df),sadfsd,asdf)";
String test2 = "print(print(asdf),sadfsd,as<caret>df)";
String test3 = "print(print(asdf),sadfsd,asdf); int a = 3<caret>;";
String test4 = "if (1 + 1 <caret> == 2)";
String test5 = "asdf";

void main() {
  print(parameterInfo(test,test.lastIndexOf("<caret>")));
  print(parameterInfo(test2,test2.lastIndexOf("<caret>")));
  print(parameterInfo(test3,test3.lastIndexOf("<caret>")));
  print(parameterInfo(test4,test4.lastIndexOf("<caret>")));
  print(parameterInfo(test5,test5.lastIndexOf("<caret>")));
}

///Determines parameterInfo for a dart source.
///Returns null if caret is not inside parenthesis
///dart-services can determine 
///if there really is a method/functionat parameterInfo["beginParen"]-1
Map<String,int> parameterInfo(String source, int offset) {
  offset += -1;
  int parameterPosition = 0;
  int beginParen;
  bool skip = false;
  while (beginParen == null && offset > 0) {
    if (source[offset] == ",") {
      parameterPosition += 1;
    }
    if (source[offset] == "(" && !skip) {
      beginParen = offset;
      continue;
    } else if (source[offset] == ")") {
      skip = true;
    } else if (source[offset] == ";") {
      return null;
    } else if (skip == true && source[offset] == "(") {
      skip = false;
    }
    offset += -1;
  }
  return beginParen == null ? null : {
    "beginParen" : beginParen,
    "parameterPosition" : parameterPosition
  };
}