// not including <> as they are ambiguous (< is also a comparison operator)
static S testBracketHygiene_op    = "([{";
static S testBracketHygiene_close = ")]}";

static bool testBracketHygiene(S s) {
  ret testBracketHygiene(s, testBracketHygiene_op, testBracketHygiene_close, null);
}

static bool testBracketHygiene(S s, Var<S> msg) {
  ret testBracketHygiene(s, testBracketHygiene_op, testBracketHygiene_close, msg);
}

static bool testBracketHygiene(S s, S op, S close, Var<S> msg) {
  S t = getUnclosedStringLiteral(s);
  if (t != null) {
    if (msg != null)
      msg.set("Unclosed string literal: " + quote(t));
    false;
  }
  
  L<S> tok = javaTok(s);
  new Map<Int, Int> map;
  L<int> stack = getBracketMap2(tok, map, op, close);
  if (nempty(stack)) {
    if (msg != null)
      msg.set("Bad hygiene - " + n(l(stack), "bracket") + " not closed");
    false;
  }
  
  if (map.containsKey(0)) {
    if (msg != null)
      msg.set("Bad hygiene - bracket not opened (" + quote(tok.get(map.get(0))) + ")");
    false;
  }
  
  for (int i : keys(map)) {
    int j = map.get(i);
    S a = tok.get(i), b = tok.get(j);
    int ai = op.indexOf(a), bi = close.indexOf(b);
    if (ai != bi) {
      if (msg != null)
        msg.set("Bad hygiene - brackets don't match (" + quote(a) + " vs " + quote(b) + ")");
      false;
    }
  }
  
  if (msg != null)
    msg.set("Hygiene OK!");
  true;
}