Add ArrayStack

src/main/java/org/warp/commonutils/type/ArrayStack.java

@@ -0,0 +1,15 @@
+package org.warp.commonutils.type;
+
+import it.unimi.dsi.fastutil.objects.ObjectArrayList;
+import java.util.Collection;
+
+public class ArrayStack<T> extends FastUtilStackWrapper<T> {
+
+	public ArrayStack() {
+		super(new ObjectArrayList<T>());
+	}
+
+	public ArrayStack(Collection<T> stack) {
+		super(new ObjectArrayList<T>(stack));
+	}
+}

src/main/java/org/warp/commonutils/type/FastUtilStackSetWrapper.java

@@ -7,8 +7,8 @@ import org.warp.commonutils.error.IndexOutOfBoundsException;
 
 public class FastUtilStackSetWrapper<T> implements StackSet<T>, Collection<T> {
 
-	private final AddStrategy addStrategy;
-	private final ObjectLinkedOpenHashSet<T> linkedHashSet;
+	protected final AddStrategy addStrategy;
+	protected final ObjectLinkedOpenHashSet<T> linkedHashSet;
 
 	/**
 	 * The first element will be the head
@@ -133,4 +133,10 @@ public class FastUtilStackSetWrapper<T> implements StackSet<T>, Collection<T> {
 		}
 		return it.next();
 	}
+
+	@SuppressWarnings("MethodDoesntCallSuperMethod")
+	@Override
+	public FastUtilStackSetWrapper<T> clone() {
+		return new FastUtilStackSetWrapper<>(linkedHashSet.clone(), addStrategy);
+	}
 }

src/main/java/org/warp/commonutils/type/FastUtilStackWrapper.java

@@ -0,0 +1,123 @@
+package org.warp.commonutils.type;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Objects;
+import java.util.StringJoiner;
+import org.jetbrains.annotations.NotNull;
+
+public class FastUtilStackWrapper<T> implements Stack<T>, Collection<T> {
+
+	private final it.unimi.dsi.fastutil.Stack<T> stack;
+	private final Collection<T> collection;
+
+	public <U extends it.unimi.dsi.fastutil.Stack<T> & Collection<T>> FastUtilStackWrapper(U stack) {
+		this.stack = stack;
+		this.collection = stack;
+	}
+
+	@Override
+	public void push(T o) {
+		this.stack.push(o);
+	}
+
+	@Override
+	public T pop() {
+		return this.stack.pop();
+	}
+
+	@Override
+	public int size() {
+		return collection.size();
+	}
+
+	@Override
+	public boolean isEmpty() {
+		return this.stack.isEmpty();
+	}
+
+	@Override
+	public boolean contains(Object o) {
+		return collection.contains(o);
+	}
+
+	@NotNull
+	@Override
+	public Iterator<T> iterator() {
+		return collection.iterator();
+	}
+
+	@NotNull
+	@Override
+	public Object[] toArray() {
+		return collection.toArray();
+	}
+
+	@NotNull
+	@Override
+	public <T1> T1[] toArray(@NotNull T1[] a) {
+		//noinspection SuspiciousToArrayCall
+		return collection.toArray(a);
+	}
+
+	@Override
+	public boolean add(T t) {
+		return collection.add(t);
+	}
+
+	@Override
+	public boolean remove(Object o) {
+		return collection.remove(o);
+	}
+
+	@Override
+	public boolean containsAll(@NotNull Collection<?> c) {
+		return collection.containsAll(c);
+	}
+
+	@Override
+	public boolean addAll(@NotNull Collection<? extends T> c) {
+		return collection.addAll(c);
+	}
+
+	@Override
+	public boolean removeAll(@NotNull Collection<?> c) {
+		return collection.removeAll(c);
+	}
+
+	@Override
+	public boolean retainAll(@NotNull Collection<?> c) {
+		return collection.retainAll(c);
+	}
+
+	@Override
+	public void clear() {
+		collection.clear();
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) {
+			return true;
+		}
+		if (o == null || getClass() != o.getClass()) {
+			return false;
+		}
+
+		FastUtilStackWrapper<?> that = (FastUtilStackWrapper<?>) o;
+
+		return Objects.equals(stack, that.stack);
+	}
+
+	@Override
+	public int hashCode() {
+		return stack != null ? stack.hashCode() : 0;
+	}
+
+	@Override
+	public String toString() {
+		return new StringJoiner(", ", FastUtilStackWrapper.class.getSimpleName() + "[", "]")
+				.add("stack=" + stack)
+				.toString();
+	}
+}

src/main/java/org/warp/commonutils/type/HashStackSet.java

@@ -16,4 +16,13 @@ public class HashStackSet<T> extends FastUtilStackSetWrapper<T> {
 	public HashStackSet(AddStrategy addStrategy) {
 		super(new ObjectLinkedOpenHashSet<>(), addStrategy);
 	}
+
+	private HashStackSet(ObjectLinkedOpenHashSet<T> linkedHashSet, AddStrategy addStrategy) {
+		super(linkedHashSet, addStrategy);
+	}
+
+	@Override
+	public HashStackSet<T> clone() {
+		return new HashStackSet<>(super.linkedHashSet.clone(), super.addStrategy);
+	}
 }

src/main/java/org/warp/commonutils/type/Stack.java

@@ -0,0 +1,43 @@
+package org.warp.commonutils.type;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import org.warp.commonutils.error.IndexOutOfBoundsException;
+
+/**
+ * A stack
+ *
+ * <p>A stack must provide the classical {@link #push(Object)} and
+ * {@link #pop()} operations, but may be also <em>peekable</em> to some extent: it may provide just the {@link #top()}
+ * function, or even a more powerful {@link #peek(int)} method that provides access to all elements on the stack
+ * (indexed from the top, which has index 0).
+ */
+
+public interface Stack<K> extends it.unimi.dsi.fastutil.Stack<K> {
+
+	/**
+	 * Pop multiple times
+	 * @param count the number of times to pop
+	 * @return list of popped elements
+	 */
+	default List<K> pop(int count) {
+		if (count < 0) {
+			throw new IndexOutOfBoundsException(count);
+		}
+		var items = new ArrayList<K>(count);
+		for (int i = 0; i < count; i++) {
+			items.add(this.pop());
+		}
+		return items;
+	}
+
+	static <T> Stack<T> create() {
+		return new ArrayStack<>();
+	}
+
+	static <T, U extends Stack<T> & Collection<T>> Stack<T> wrap(U stack) {
+		return new FastUtilStackWrapper<>(stack);
+	}
+
+}

src/main/java/org/warp/commonutils/type/StackSet.java

@@ -1,11 +1,11 @@
 package org.warp.commonutils.type;
 
 import it.unimi.dsi.fastutil.objects.ObjectLinkedOpenHashSet;
-import java.util.Iterator;
+import java.util.ArrayList;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.NoSuchElementException;
-import java.util.Objects;
-import java.util.function.Predicate;
+import org.warp.commonutils.error.IndexOutOfBoundsException;
 
 /**
  * A stack but with the behavior of a Linked HashSet
@@ -27,6 +27,22 @@ public interface StackSet<K> {
 	 */
 	boolean push(K o);
 
+	/**
+	 * Pop multiple times
+	 * @param count the number of times to pop
+	 * @return list of popped elements
+	 */
+	default List<K> pop(int count) {
+		if (count < 0) {
+			throw new IndexOutOfBoundsException(count);
+		}
+		var items = new ArrayList<K>(count);
+		for (int i = 0; i < count; i++) {
+			items.add(this.pop());
+		}
+		return items;
+	}
+
 	/**
 	 * Pops the top off the stack.
 	 *