sS tok_moveImportsUp(S src) {
  ret join(tok_moveImportsUp(javaTok(src)));
}

static LS tok_moveImportsUp(LS tok) {
  new StringBuilder buf;
  
  //print("tok_moveImportsUp n=" + l(tok));
  //print("Source begins: " + quote(shorten(join(tok), 200)));
  
  // scan imports on top
  bool change = false;
  int i;
  new Set<S> have;
  for (i = 1; i < l(tok); i += 2)
    if (eq(tok.get(i), 'import)) {
      int j = indexOf(tok, i+2, ";");
      if (j < 0) break;
      S s = joinSubList(tok, i, j+1);
      have.add(s);
      i = j;
    } else break;
  
  //print("tok_moveImportsUp have " + l(have) + " after " + i);
  
  // scan imports in text
  for (; i < l(tok); i += 2)
    if (eq(tok.get(i), 'import)) {
      int j = indexOf(tok, i+2, ";");
      if (j < 0) continue; // huh?
      S s = joinSubList(tok, i, j+1);
      //print("Found import at " + i + ": " + s);
      if (!have.contains(s)) {
        buf.append(s).append("\n");
        have.add(s);
      }
      replaceTokens/*_reTok*/(tok, i, j+1, "");
      change = true;
      i -= 2;
    }
    
  if (nempty(buf)) {
    if (l(tok) == 1) addAll(tok, "", "");
    tok.set(1, str(buf)+"\n"+tok.get(1));
    change = true;
    //reTok(tok, 1, 2);
  }
    
  if (change) reTok(tok);
  ret tok;
}

Began life as a copy of #1000608