8187443: Forest Consolidation: Move files to unified layout

Reviewed-by: darcy, ihse

src/java.base/share/classes/java/util/AbstractSet.java

@@ -0,0 +1,186 @@
+/*
+ * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.util;
+
+/**
+ * This class provides a skeletal implementation of the {@code Set}
+ * interface to minimize the effort required to implement this
+ * interface. <p>
+ *
+ * The process of implementing a set by extending this class is identical
+ * to that of implementing a Collection by extending AbstractCollection,
+ * except that all of the methods and constructors in subclasses of this
+ * class must obey the additional constraints imposed by the {@code Set}
+ * interface (for instance, the add method must not permit addition of
+ * multiple instances of an object to a set).<p>
+ *
+ * Note that this class does not override any of the implementations from
+ * the {@code AbstractCollection} class.  It merely adds implementations
+ * for {@code equals} and {@code hashCode}.<p>
+ *
+ * This class is a member of the
+ * <a href="{@docRoot}/java/util/package-summary.html#CollectionsFramework">
+ * Java Collections Framework</a>.
+ *
+ * @param <E> the type of elements maintained by this set
+ *
+ * @author  Josh Bloch
+ * @author  Neal Gafter
+ * @see Collection
+ * @see AbstractCollection
+ * @see Set
+ * @since 1.2
+ */
+
+public abstract class AbstractSet<E> extends AbstractCollection<E> implements Set<E> {
+    /**
+     * Sole constructor.  (For invocation by subclass constructors, typically
+     * implicit.)
+     */
+    protected AbstractSet() {
+    }
+
+    // Comparison and hashing
+
+    /**
+     * Compares the specified object with this set for equality.  Returns
+     * {@code true} if the given object is also a set, the two sets have
+     * the same size, and every member of the given set is contained in
+     * this set.  This ensures that the {@code equals} method works
+     * properly across different implementations of the {@code Set}
+     * interface.<p>
+     *
+     * This implementation first checks if the specified object is this
+     * set; if so it returns {@code true}.  Then, it checks if the
+     * specified object is a set whose size is identical to the size of
+     * this set; if not, it returns false.  If so, it returns
+     * {@code containsAll((Collection) o)}.
+     *
+     * @param o object to be compared for equality with this set
+     * @return {@code true} if the specified object is equal to this set
+     */
+    public boolean equals(Object o) {
+        if (o == this)
+            return true;
+
+        if (!(o instanceof Set))
+            return false;
+        Collection<?> c = (Collection<?>) o;
+        if (c.size() != size())
+            return false;
+        try {
+            return containsAll(c);
+        } catch (ClassCastException unused)   {
+            return false;
+        } catch (NullPointerException unused) {
+            return false;
+        }
+    }
+
+    /**
+     * Returns the hash code value for this set.  The hash code of a set is
+     * defined to be the sum of the hash codes of the elements in the set,
+     * where the hash code of a {@code null} element is defined to be zero.
+     * This ensures that {@code s1.equals(s2)} implies that
+     * {@code s1.hashCode()==s2.hashCode()} for any two sets {@code s1}
+     * and {@code s2}, as required by the general contract of
+     * {@link Object#hashCode}.
+     *
+     * <p>This implementation iterates over the set, calling the
+     * {@code hashCode} method on each element in the set, and adding up
+     * the results.
+     *
+     * @return the hash code value for this set
+     * @see Object#equals(Object)
+     * @see Set#equals(Object)
+     */
+    public int hashCode() {
+        int h = 0;
+        Iterator<E> i = iterator();
+        while (i.hasNext()) {
+            E obj = i.next();
+            if (obj != null)
+                h += obj.hashCode();
+        }
+        return h;
+    }
+
+    /**
+     * Removes from this set all of its elements that are contained in the
+     * specified collection (optional operation).  If the specified
+     * collection is also a set, this operation effectively modifies this
+     * set so that its value is the <i>asymmetric set difference</i> of
+     * the two sets.
+     *
+     * <p>This implementation determines which is the smaller of this set
+     * and the specified collection, by invoking the {@code size}
+     * method on each.  If this set has fewer elements, then the
+     * implementation iterates over this set, checking each element
+     * returned by the iterator in turn to see if it is contained in
+     * the specified collection.  If it is so contained, it is removed
+     * from this set with the iterator's {@code remove} method.  If
+     * the specified collection has fewer elements, then the
+     * implementation iterates over the specified collection, removing
+     * from this set each element returned by the iterator, using this
+     * set's {@code remove} method.
+     *
+     * <p>Note that this implementation will throw an
+     * {@code UnsupportedOperationException} if the iterator returned by the
+     * {@code iterator} method does not implement the {@code remove} method.
+     *
+     * @param  c collection containing elements to be removed from this set
+     * @return {@code true} if this set changed as a result of the call
+     * @throws UnsupportedOperationException if the {@code removeAll} operation
+     *         is not supported by this set
+     * @throws ClassCastException if the class of an element of this set
+     *         is incompatible with the specified collection
+     * (<a href="Collection.html#optional-restrictions">optional</a>)
+     * @throws NullPointerException if this set contains a null element and the
+     *         specified collection does not permit null elements
+     * (<a href="Collection.html#optional-restrictions">optional</a>),
+     *         or if the specified collection is null
+     * @see #remove(Object)
+     * @see #contains(Object)
+     */
+    public boolean removeAll(Collection<?> c) {
+        Objects.requireNonNull(c);
+        boolean modified = false;
+
+        if (size() > c.size()) {
+            for (Object e : c)
+                modified |= remove(e);
+        } else {
+            for (Iterator<?> i = iterator(); i.hasNext(); ) {
+                if (c.contains(i.next())) {
+                    i.remove();
+                    modified = true;
+                }
+            }
+        }
+        return modified;
+    }
+
+}