switch(modiferTree.getType()) {
case MqlParser.INC:
field = child(modiferTree, 0).getText();
value = readVariableLiteral(child(modiferTree, 1), ctx);
assertType(value, modiferTree, Number.class);
modifier.inc(field, Number.class.cast(value));
break;
case MqlParser.SET:
field = child(modiferTree, 0).getText();
value = readVariableLiteral(child(modiferTree, 1), ctx);
modifier.set(field, value);