Method reentrantComputeIfAbsent

java/dagger/internal/codegen/Util.java:90–100

A version of Map#computeIfAbsent(Object, Function) that allows mappingFunction to update map.

(
      Map<K, V> map, K key, Function<? super K, ? extends V> mappingFunction)

   * to update {@code map}.
   */
  static <K, V> V reentrantComputeIfAbsent(
      Map<K, V> map, K key, Function<? super K, ? extends V> mappingFunction) {
    V value = map.get(key);
    if (value == null) {
      value = mappingFunction.apply(key);
      if (value != null) {
        map.put(key, value);
      }
    }
    return value;
  }

  private Util() {}
}