| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.flink.statefun.sdk.kafka; |
| |
| import java.util.NoSuchElementException; |
| import java.util.Objects; |
| import java.util.Properties; |
| import javax.annotation.Nullable; |
| |
| /** |
| * Utility class to represent an optional config, which may have a predefined default value. |
| * |
| * @param <T> type of the configuration value. |
| */ |
| final class OptionalConfig<T> { |
| |
| private final T defaultValue; |
| private T value; |
| |
| static <T> OptionalConfig<T> withDefault(T defaultValue) { |
| Objects.requireNonNull(defaultValue); |
| return new OptionalConfig<>(defaultValue); |
| } |
| |
| static <T> OptionalConfig<T> withoutDefault() { |
| return new OptionalConfig<>(null); |
| } |
| |
| private OptionalConfig(@Nullable T defaultValue) { |
| this.defaultValue = defaultValue; |
| } |
| |
| void set(T value) { |
| this.value = Objects.requireNonNull(value); |
| } |
| |
| T get() { |
| if (!isSet() && !hasDefault()) { |
| throw new NoSuchElementException( |
| "A value has not been set, and no default value was defined."); |
| } |
| return isSet() ? value : defaultValue; |
| } |
| |
| void overwritePropertiesIfPresent(Properties properties, String key) { |
| if (isSet() || (!properties.containsKey(key) && hasDefault())) { |
| properties.setProperty(key, get().toString()); |
| } |
| } |
| |
| private boolean hasDefault() { |
| return defaultValue != null; |
| } |
| |
| private boolean isSet() { |
| return value != null; |
| } |
| } |