the handling of a block in the recursive interpreter of a subgrammar of Lua

Interpreter_block.java

    @Override
    public Object visitBlock(Block block, Object arg) throws Exception {
        for (int i = 0; i < block.stats.size(); i++) {
            Stat stat = block.stats.get(i);
            try {
                stat.visit(this, arg);
            } catch (BreakException e) {
                // need to know if break inside a loop
                if (stat instanceof StatWhile ||
                        stat instanceof StatRepeat) {
                    continue;
                }
                throw e;
            } catch (GotoException e) {
                StatLabel target = e.target;
                if (target.enclosingBlock == block) {
                    i = target.index;
                } else {
                    throw e;
                }
            } catch (ReThrownReturnException e) {
                throw e;
            } catch (ReturnException e) {
                if (i != block.stats.size() - 1)
                    throw new LuaRuntimeException(
                            "Return statement is not the last statement in its block."
                    );
                throw new ReThrownReturnException(e);
            }
        }
        return null;
    }