Class AbstractBiMap

output/java_guava/1.4.13/AbstractBiMap.java:49–457

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);
    }

    void setInverse(AbstractBiMap<V, K> inverse) {
    this.inverse = inverse;