import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.reflect.Field;
+import java.util.AbstractMap.SimpleImmutableEntry;
import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Arrays;
+import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
-import java.util.Objects;
import java.util.Set;
import javax.annotation.Nonnull;
* a backing array. This is useful for situations where the same key set is shared across a multitude of maps, as this
* class uses a global cache to share the key-to-offset mapping.
*
- * This map supports creation of value objects on the fly. To achieve that, subclasses should override {@link #valueToObject(Object)},
- * {@link #objectToValue(Object, Object)}, {@link #clone()} and {@link #toModifiableMap()} methods.
- *
* @param <K> the type of keys maintained by this map
* @param <V> the type of mapped values
*/
@Beta
-public class ImmutableOffsetMap<K, V> extends AbstractLazyValueMap<K, V> implements Cloneable, UnmodifiableMapPhase<K, V>, Serializable {
+public final class ImmutableOffsetMap<K, V> implements UnmodifiableMapPhase<K, V>, Serializable {
private static final long serialVersionUID = 1L;
private final Map<K, Integer> offsets;
- private final Object[] objects;
+ private final V[] objects;
+ private int hashCode;
/**
* Construct a new instance backed by specified key-to-offset map and array of objects.
* @param objects Array of value object, may not be null. The array is stored as is, the caller
* is responsible for ensuring its contents remain unmodified.
*/
- ImmutableOffsetMap(@Nonnull final Map<K, Integer> offsets, @Nonnull final Object[] objects) {
+ ImmutableOffsetMap(@Nonnull final Map<K, Integer> offsets, @Nonnull final V[] objects) {
this.offsets = Preconditions.checkNotNull(offsets);
this.objects = Preconditions.checkNotNull(objects);
Preconditions.checkArgument(offsets.size() == objects.length);
*
* @param m Instance to share data with, may not be null.
*/
- protected ImmutableOffsetMap(@Nonnull final ImmutableOffsetMap<K, V> m) {
+ ImmutableOffsetMap(@Nonnull final ImmutableOffsetMap<K, V> m) {
this.offsets = m.offsets;
this.objects = m.objects;
}
* @return An isolated, immutable copy of the input map
*/
@Nonnull public static <K, V> Map<K, V> copyOf(@Nonnull final Map<K, V> m) {
- // Prevent a copy
- if (m instanceof ImmutableOffsetMap) {
+ // Prevent a copy. Note that ImmutableMap is not listed here because of its potentially larger keySet overhead.
+ if (m instanceof ImmutableOffsetMap || m instanceof SharedSingletonMap) {
return m;
}
- // Better-packed
+ // Familiar and efficient to copy
+ if (m instanceof MutableOffsetMap) {
+ return ((MutableOffsetMap<K, V>) m).toUnmodifiableMap();
+ }
+
final int size = m.size();
if (size == 0) {
+ // Shares a single object
return ImmutableMap.of();
}
if (size == 1) {
- return ImmutableMap.copyOf(m);
- }
-
- // Familiar and efficient
- if (m instanceof MutableOffsetMap) {
- return ((MutableOffsetMap<K, V>) m).toUnmodifiableMap();
+ // Efficient single-entry implementation
+ final Entry<K, V> e = m.entrySet().iterator().next();
+ return SharedSingletonMap.of(e.getKey(), e.getValue());
}
final Map<K, Integer> offsets = OffsetMapCache.offsetsFor(m.keySet());
}
@Override
- public final int size() {
+ public int size() {
return offsets.size();
}
@Override
- public final boolean isEmpty() {
+ public boolean isEmpty() {
return offsets.isEmpty();
}
+ @Override
+ public int hashCode() {
+ if (hashCode != 0) {
+ return hashCode;
+ }
+
+ int result = 0;
+ for (Entry<K, Integer> e : offsets.entrySet()) {
+ result += e.getKey().hashCode() ^ objects[e.getValue()].hashCode();
+ }
+
+ hashCode = result;
+ return result;
+ }
+
@Override
public boolean equals(final Object o) {
if (o == this) {
return true;
}
- if (o == null) {
+ if (!(o instanceof Map)) {
return false;
}
if (o instanceof ImmutableOffsetMap) {
final ImmutableOffsetMap<?, ?> om = (ImmutableOffsetMap<?, ?>) o;
- if (offsets.equals(om.offsets) && Arrays.deepEquals(objects, om.objects)) {
- return true;
+
+ // If the offset match, the arrays have to match, too
+ if (offsets.equals(om.offsets)) {
+ return Arrays.deepEquals(objects, om.objects);
}
} else if (o instanceof MutableOffsetMap) {
// Let MutableOffsetMap do the actual work.
return o.equals(this);
- } else if (o instanceof Map) {
- final Map<?, ?> om = (Map<?, ?>)o;
+ }
- // Size and key sets have to match
- if (size() != om.size() || !keySet().equals(om.keySet())) {
- return false;
- }
+ final Map<?, ?> other = (Map<?, ?>)o;
- try {
- // Ensure all objects are present
- for (Entry<K, Integer> e : offsets.entrySet()) {
- final V v = objectToValue(e.getKey(), objects[e.getValue()]);
- if (!v.equals(om.get(e.getKey()))) {
- return false;
- }
+ // Size and key sets have to match
+ if (size() != other.size() || !keySet().equals(other.keySet())) {
+ return false;
+ }
+
+ try {
+ // Ensure all objects are present
+ for (Entry<K, Integer> e : offsets.entrySet()) {
+ if (!objects[e.getValue()].equals(other.get(e.getKey()))) {
+ return false;
}
- } catch (ClassCastException e) {
- // Can be thrown by om.get() and indicate we have incompatible key types
- return false;
}
-
- return true;
+ } catch (ClassCastException e) {
+ // Can be thrown by other.get() indicating we have incompatible key types
+ return false;
}
- return false;
+ return true;
}
@Override
- public final boolean containsKey(final Object key) {
+ public boolean containsKey(final Object key) {
return offsets.containsKey(key);
}
@Override
- public final boolean containsValue(final Object value) {
- @SuppressWarnings("unchecked")
- final Object obj = valueToObject((V)value);
+ public boolean containsValue(final Object value) {
for (Object o : objects) {
- if (Objects.equals(obj, o)) {
+ if (value.equals(o)) {
return true;
}
}
return false;
}
- @SuppressWarnings("unchecked")
@Override
- public final V get(final Object key) {
+ public V get(final Object key) {
final Integer offset = offsets.get(key);
- if (offset == null) {
- return null;
- }
+ return offset == null ? null : objects[offset];
+ }
- return objectToValue((K) key, objects[offset]);
+ @Override
+ public V remove(final Object key) {
+ throw new UnsupportedOperationException();
}
@Override
- public final V remove(final Object key) {
+ public V put(final K key, final V value) {
throw new UnsupportedOperationException();
}
@Override
- public final void putAll(final Map<? extends K, ? extends V> m) {
+ public void putAll(final Map<? extends K, ? extends V> m) {
throw new UnsupportedOperationException();
}
@Override
- public final void clear() {
+ public void clear() {
throw new UnsupportedOperationException();
}
@Override
- public final Set<K> keySet() {
+ public Set<K> keySet() {
return offsets.keySet();
}
@Override
- public final Set<Entry<K, V>> entrySet() {
+ public Collection<V> values() {
+ return new ConstantArrayCollection<>(objects);
+ }
+
+ @Override
+ public Set<Entry<K, V>> entrySet() {
return new EntrySet();
}
}
@Override
- public ImmutableOffsetMap<K, V> clone() throws CloneNotSupportedException {
- return new ImmutableOffsetMap<>(this);
+ public String toString() {
+ final StringBuilder sb = new StringBuilder("{");
+ final Iterator<K> it = offsets.keySet().iterator();
+ int i = 0;
+ while (it.hasNext()) {
+ sb.append(it.next());
+ sb.append('=');
+ sb.append(objects[i++]);
+
+ if (it.hasNext()) {
+ sb.append(", ");
+ }
+ }
+
+ return sb.append('}').toString();
}
Map<K, Integer> offsets() {
return offsets;
}
- Object[] objects() {
+ V[] objects() {
return objects;
}
@Override
public Entry<K, V> next() {
final Entry<K, Integer> e = it.next();
- return new SimpleEntry<>(e.getKey(), objectToValue(e.getKey(), objects[e.getValue()]));
+ return new SimpleImmutableEntry<>(e.getKey(), objects[e.getValue()]);
}
};
}
Code Review / yangtools.git / blobdiff