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Immutable Clojure collections and a Transformation abstraction for Java 8+, immutably, type-safely, and with good performance. Name will change to "Paguro" in November 2016.
// Copyright 2015 PlanBase Inc. & Glen Peterson
//
// Licensed 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.organicdesign.fp.collections;
import java.util.Collection;
import java.util.Set;
import java.util.function.Predicate;
/** An unmodifiable set */
public interface UnmodSet extends UnmodCollection, Set {
// ========================================== Static ==========================================
/**
Implements equals and hashCode() methods to make defining unmod sets easier, especially for
implementing Map.keySet() and such.
*/
abstract class AbstractUnmodSet implements UnmodSet {
@Override public boolean equals(Object other) {
if (this == other) { return true; }
if ( !(other instanceof Set) ) { return false; }
Set that = (Set) other;
return (size() == that.size()) &&
containsAll(that);
}
@Override public int hashCode() { return UnmodIterable.hashCode(this); }
}
// ========================================= Instance =========================================
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default boolean add(E e) {
throw new UnsupportedOperationException("Modification attempted");
}
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default boolean addAll(Collection c) {
throw new UnsupportedOperationException("Modification attempted");
}
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default void clear() {
throw new UnsupportedOperationException("Modification attempted");
}
/**
Returns true if the set contains the given item. This is the defining method of a set.
Sets have to override this because the default implementation in UnmodCollection is O(n)
whereas a sorted set should be O(log n) or O(1).
*/
@Override boolean contains(Object o);
/** {@inheritDoc} */
@Override default boolean containsAll(Collection items) {
for (Object item : items) {
if (!this.contains(item)) { return false; }
}
return true;
}
// boolean equals(Object o)
// int hashCode()
/**
This is a convenience method inherited from Collection that returns true if size() == 0 (if
this set contains no elements).
*/
@Override default boolean isEmpty() { return size() == 0; }
/**
Iterates over contents with no guarantees about their ordering.
{@inheritDoc}
*/
@Override
UnmodIterator iterator();
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default boolean remove(Object o) {
throw new UnsupportedOperationException("Modification attempted");
}
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default boolean removeAll(Collection c) {
throw new UnsupportedOperationException("Modification attempted");
}
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default boolean retainAll(Collection c) {
throw new UnsupportedOperationException("Modification attempted");
}
// int size(); // This is limiting for sets, but not so much that it has to be deprecated.
// default Spliterator spliterator()
/**
This method goes against Josh Bloch's Item 25: "Prefer Lists to Arrays", but is provided for
backwards compatibility in some performance-critical situations. If you really need an array,
consider using the somewhat type-safe version of this method instead, but read the caveats
first.
{@inheritDoc}
*/
@Override default Object[] toArray() { return UnmodCollection.super.toArray(); }
/**
This method goes against Josh Bloch's Item 25: "Prefer Lists to Arrays", but is provided for
backwards compatibility in some performance-critical situations. If you need to create an
array (you almost always do) then the best way to use this method is:
MyThing[] things = col.toArray(new MyThing[coll.size()]);
Calling this method any other way causes unnecessary work to be done - an extra memory
allocation and potential garbage collection if the passed array is too small, extra effort to
fill the end of the array with nulls if it is too large.
{@inheritDoc}
*/
@SuppressWarnings("SuspiciousToArrayCall")
@Override default T[] toArray(T[] as) { return UnmodCollection.super.toArray(as); }
// Methods inherited from interface java.util.Collection
// parallelStream, removeIf, stream
/** Not allowed - this is supposed to be unmodifiable */
@SuppressWarnings("deprecation")
@Override @Deprecated default boolean removeIf(Predicate filter) {
throw new UnsupportedOperationException("Modification attempted");
}
// Methods inherited from interface java.lang.Iterable
// forEach
}