// themap is the replacement map in list form - in/out/in/out/...
static S mapBasedReplace(L<S> themap, S s) {
  L<S> tok = javaTok(s);
  for (int i = 1; i < l(tok); i += 2) {
    for (int j = 0; j < l(themap); j += 2) {
      S x = themap.get(j), y = themap.get(j+1);
      L<S> tokx = javaTok(x), toky = javaTok(y);
      mapBasedReplace_matchReplace(tok, i, tokx, toky);
    }
  }
  ret join(tok);
}

static void mapBasedReplace_matchReplace(L<S> tok, int i, L<S> tokx, L<S> toky) {
  if (tokRegionMatchIC(tok, i, tokx)) {
    clearAllTokens(tok.subList(i, i+l(tokx)-2));
    tok.set(i, join(toky));
  }
}

Began life as a copy of #1002187