/* event change; =>

   transient LinkedHashSet<Runnable> onChange;

   public selfType onChange(Runnable r) { onChange = syncAddOrCreate(onChange, r); this; }

   void change() { if (onChange != null) for (listener : onChange) pcallF_typed(listener); }

; }

*/

svoid tok_eventFunctions(LS tok) {

  int i;

  while ((i = jfind(tok, "event <id>", nIdx -> !eqGet(tok, nIdx+3, "aka"))) >= 0) {

    int iModifiers = tok_leftScanModifiers(tok, i);

    S modifiers = joinSubList(tok, iModifiers, i-1);

    int iSemicolon = i+4;

    LS tokArgs = null;

    if (eqGet(tok, i+4, "(")) {

      int argsFrom = i+6;

      int argsTo = findCodeTokens(tok, argsFrom, false, ")");

      tokArgs = subList(tok, argsFrom-1, argsTo);

      iSemicolon = argsTo+2;

    }

    int iEnd = iSemicolon+1;

    S body = "";

    if (eqGet(tok, iSemicolon, "{")) {

      iEnd = tok_findEndOfBlock(tok, iSemicolon);

      body = joinSubList(tok, iSemicolon+1, iEnd-1);

    } else if (neqGet(tok, iSemicolon, ";"))

      fail("Semicolon expected at end: " + joinSubList(tok, i, iSemicolon+1));

    S change = tok.get(i+2), prefix = "";

    if (startsWithCamelCaseWord(change, "on"))

      change = firstToLower(dropFirst(2, change));

    else if (startsWithCamelCaseWord(change, "fire")) {

      prefix = "fire";

      change = firstToLower(dropFirst(4, change));

    }

    S onChange = "on" + firstToUpper(change);

    S removeListener = "remove" + firstToUpper(change) + "Listener";

    LPairS args = tok_typesAndNamesOfParams(tokArgs);

    LS types = pairsA(args);

    S args1 = join(dropFirstAndLast(tokArgs));

    S args2 = joinWithComma(pairsB(args));

    S typeParams = joinWithComma(map tok_toNonPrimitiveTypes(types));      S listenerType = empty(args) ? "Runnable" : "IVF" + l(args) + "<" + typeParams + ">";

    S r = empty(args) ? "r" : "f";

    S fireChange = empty(prefix) ? change : prefix + firstToUpper(change);

    replaceTokens_reTok(tok, iModifiers, iEnd, 

      "\*modifiers*/ transient Set<\*listenerType*/> \*onChange*/;\n" +

      "public \*modifiers*/ selfType \*onChange*/(\*listenerType*/ \*r*/) { \*onChange*/ = createOrAddToSyncLinkedHashSet(\*onChange*/, \*r*/); this; }\n" +

      "public \*modifiers*/ selfType \*removeListener*/(\*listenerType*/ \*r*/) { main remove(\*onChange*/, \*r*/); this; }\n" +

      "public \*modifiers*/  void \*fireChange*/(\*args1*/) { \*body*/ " +

        "if (\*onChange*/ != null) for (listener : \*onChange*/) " +

        "pcallF_typed(" +

          joinNemptiesWithComma("listener", args2) + "); " +

      "}"

    );

  }

}