Class AbstractBiMap

output/java_guava/1.4.17/AbstractBiMap.java:49–464

A general-purpose bimap implementation using any two backing Map instances. Note that this class contains equals() calls that keep it from supporting IdentityHashMap backing maps. @author Kevin Bourrillion @author Mike Bostock

@GwtCompatible(emulated = true)
abstract class AbstractBiMap<K, V> extends ForwardingMap<K, V> implements BiMap<K, V>, Serializable {
  private transient Map<K, V> delegate;
  transient AbstractBiMap<V, K> inverse;

  /** Package-private constructor for creating a map-backed bimap. */

  AbstractBiMap(Map<K, V> forward, Map<V, K> backward) {
    setDelegates(forward, backward);
  }

  /** Private constructor for inverse bimap. */

  private AbstractBiMap(Map<K, V> backward, AbstractBiMap<V, K> forward) {
    delegate = backward;
    inverse = forward;
  }

  @Override
  protected Map<K, V> delegate() {
    return delegate;
  }

  /**
   * Returns its input, or throws an exception if this is not a valid key.
   */

  @CanIgnoreReturnValue
  K checkKey(@Nullable K key) {
    return key;
  }

  /**
   * Returns its input, or throws an exception if this is not a valid value.
   */

  @CanIgnoreReturnValue
  V checkValue(@Nullable V value) {
    return value;
  }

  /**
   * Specifies the delegate maps going in each direction. Called by the
   * constructor and by subclasses during deserialization.
   */


  void setDelegates(Map<K, V> forward, Map<V, K> backward) {
    checkState(delegate == null);
    checkState(inverse == null);
    checkArgument(forward.isEmpty());
    checkArgument(backward.isEmpty());
    checkArgument(forward != backward);
    delegate = forward;
    inverse = new Inverse<V, K>(backward, this);
  }