Implemented an efficient integer set class that uses a sorted array of

integers to maintain its contents.


git-svn-id: https://samskivert.googlecode.com/svn/trunk@559 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/util/ArrayIntSet.java

@@ -0,0 +1,274 @@
+//
+// $Id: ArrayIntSet.java,v 1.1 2002/02/03 07:10:16 mdb Exp $
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library 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
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import java.util.AbstractSet;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+/**
+ * Provides an {@link IntSet} implementation using a sorted array of
+ * integers to maintain the contents of the set.
+ */
+public class ArrayIntSet extends AbstractSet
+    implements IntSet
+{
+    // documentation inherited from interface
+    public int size ()
+    {
+        return _size;
+    }
+
+    // documentation inherited from interface
+    public boolean isEmpty ()
+    {
+        return _size == 0;
+    }
+
+    // documentation inherited from interface
+    public boolean contains (Object o)
+    {
+        return contains(((Integer)o).intValue());
+    }
+
+    // documentation inherited from interface
+    public boolean contains (int value)
+    {
+        return (binarySearch(value) >= 0);
+    }
+
+    // documentation inherited from interface
+    public Iterator iterator ()
+    {
+        return new Iterator() {
+            public boolean hasNext () {
+                return (_pos < _size);
+            }
+
+            public Object next () {
+                if (_pos == _size) {
+                    throw new NoSuchElementException();
+                } else {
+                    return new Integer(_values[_pos++]);
+                }
+            }
+
+            public void remove () {
+                throw new UnsupportedOperationException();
+            }
+
+            protected int _pos;
+        };
+    }
+
+    // documentation inherited from interface
+    public Object[] toArray ()
+    {
+        return toArray(new Integer[_size]);
+    }
+
+    // documentation inherited from interface
+    public Object[] toArray (Object[] a)
+    {
+        for (int i = 0; i < _size; i++) {
+            a[i] = new Integer(_values[i]);
+        }
+        return a;
+    }
+
+    // documentation inherited from interface
+    public int[] toIntArray ()
+    {
+        int[] values = new int[_size];
+        System.arraycopy(_values, 0, values, 0, _size);
+        return values;
+    }
+
+    // documentation inherited from interface
+    public boolean add (Object o)
+    {
+        return add(((Integer)o).intValue());
+    }
+
+    // documentation inherited from interface
+    public boolean add (int value)
+    {
+        int index = binarySearch(value);
+        if (index >= 0) {
+            return false;
+        }
+
+        // convert the return value into the insertion point
+        index += 1;
+        index *= -1;
+
+        // expand the values array if necessary, leaving room for the
+        // newly added element
+        int valen = _values.length;
+        int[] source = _values;
+        if (valen == _size) {
+            _values = new int[valen*2];
+            System.arraycopy(source, 0, _values, 0, index);
+        }
+
+        // shift and insert
+        if (_size > index) {
+            System.arraycopy(source, index,
+                             _values, index+1, _size-index);
+        }
+        _values[index] = value;
+
+        // increment our size
+        _size += 1;
+
+        return true;
+    }
+
+    /**
+     * Add all of the values in the supplied array to the set.
+     *
+     * @param values elements to be added to this set.
+     *
+     * @return <tt>true</tt> if this set did not already contain all of
+     * the specified elements.
+     */
+    public boolean add (int[] values)
+    {
+        boolean modified = false;
+        int vlength = values.length;
+        for (int i = 0; i < vlength; i++) {
+            modified = (add(values[i]) || modified);
+        }
+        return modified;
+    }
+
+    // documentation inherited from interface
+    public boolean remove (Object o)
+    {
+        return remove(((Integer)o).intValue());
+    }
+
+    // documentation inherited from interface
+    public boolean remove (int value)
+    {
+        int index = binarySearch(value);
+        if (index > 0) {
+            System.arraycopy(_values, index, _values, index+1, --_size-index);
+            _values[_size] = 0;
+            return true;
+        }
+        return false;
+    }
+
+    // documentation inherited from interface
+    public boolean containsAll (Collection c)
+    {
+        Iterator iter = c.iterator();
+        while (iter.hasNext()) {
+            if (!contains(iter.next())) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    // documentation inherited from interface
+    public boolean addAll (Collection c)
+    {
+        boolean modified = false;
+        Iterator iter = c.iterator();
+        while (iter.hasNext()) {
+            modified = (add(iter.next()) || modified);
+        }
+        return modified;
+    }
+
+    // documentation inherited from interface
+    public boolean retainAll (Collection c)
+    {
+        throw new UnsupportedOperationException();
+    }
+
+    // documentation inherited from interface
+    public void clear ()
+    {
+        Arrays.fill(_values, 0);
+        _size = 0;
+    }
+
+    // documentation inherited from interface
+    public boolean equals (Object o)
+    {
+        if (o instanceof ArrayIntSet) {
+            ArrayIntSet other = (ArrayIntSet)o;
+            if (other._size == _size) {
+                return Arrays.equals(_values, other._values);
+            }
+        }
+
+        return false;
+    }
+
+    // documentation inherited from interface
+    public int hashCode ()
+    {
+        int hashCode = 0;
+        for (int i = 0; i < _size; i++) {
+            hashCode ^= _values[i];
+        }
+        return hashCode;
+    }
+
+    /**
+     * Performs a binary search on our values array, looking for the
+     * specified value. Swiped from <code>java.util.Arrays</code> because
+     * those wankers didn't provide a means by which to perform a binary
+     * search on a subset of an array.
+     */
+    protected int binarySearch (int key)
+    {
+	int low = 0;
+	int high = _size-1;
+
+	while (low <= high) {
+	    int mid = (low + high) >> 1;
+	    int midVal = _values[mid];
+
+	    if (midVal < key) {
+		low = mid + 1;
+	    } else if (midVal > key) {
+		high = mid - 1;
+	    } else {
+		return mid; // key found
+            }
+	}
+
+	return -(low + 1);  // key not found.
+    }
+
+    /** An array containing the values in this set. */
+    protected int[] _values = new int[16];
+
+    /** The number of elements in this set. */
+    protected int _size;
+}

projects/samskivert/src/java/com/samskivert/util/IntSet.java

@@ -0,0 +1,84 @@
+//
+// $Id: IntSet.java,v 1.1 2002/02/03 07:10:16 mdb Exp $
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library 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
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import java.util.Set;
+
+/**
+ * A set that holds integers and provides accessors that eliminate the
+ * need to create and manipulate superfluous <code>Integer</code>
+ * objects. It extends the <code>Set</code> interface and therefore
+ * provides all of the standard methods (in which <code>Integer</code>
+ * objects will be converted to ints).
+ */
+public interface IntSet extends Set
+{
+    /**
+     * Returns <tt>true</tt> if this set contains the specified element.
+     *
+     * @param value element whose presence in this set is to be tested.
+     *
+     * @return <tt>true</tt> if this set contains the specified element.
+     */
+    public boolean contains (int value);
+
+    /**
+     * Adds the specified element to this set if it is not already present
+     * (optional operation). If this set already contains the specified
+     * element, the call leaves this set unchanged and returns
+     * <tt>false</tt>.  In combination with the restriction on
+     * constructors, this ensures that sets never contain duplicate
+     * elements.
+     *
+     * @param value element to be added to this set.
+     *
+     * @return <tt>true</tt> if this set did not already contain the
+     * specified element.
+     * 
+     * @throws UnsupportedOperationException if the <tt>add</tt> method is
+     * not supported by this set.
+     */
+    public boolean add (int value);
+
+    /**
+     * Removes the specified element from this set if it is present
+     * (optional operation).  Returns <tt>true</tt> if the set contained
+     * the specified element (or equivalently, if the set changed as a
+     * result of the call).  (The set will not contain the specified
+     * element once the call returns.)
+     *
+     * @param value element to be removed from this set, if present.
+     *
+     * @return true if the set contained the specified element.
+     *
+     * @throws UnsupportedOperationException if the <tt>remove</tt> method
+     * is not supported by this set.
+     */
+    public boolean remove (int value);
+
+    /**
+     * Returns an array containing all of the elements in this set.  Obeys
+     * the general contract of the <tt>Collection.toArray</tt> method.
+     *
+     * @return an array containing all of the elements in this set.
+     */
+    public int[] toIntArray ();
+}

projects/samskivert/tests/src/java/com/samskivert/util/ArrayIntSetTest.java

@@ -0,0 +1,58 @@
+//
+// $Id: ArrayIntSetTest.java,v 1.1 2002/02/03 07:10:16 mdb Exp $
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library 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
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.util;
+
+import java.util.Arrays;
+
+import junit.framework.Test;
+import junit.framework.TestCase;
+
+import com.samskivert.Log;
+
+public class ArrayIntSetTest extends TestCase
+{
+    public ArrayIntSetTest ()
+    {
+        super(ArrayIntSetTest.class.getName());
+    }
+
+    public void runTest ()
+    {
+        ArrayIntSet set = new ArrayIntSet();
+        set.add(3);
+        set.add(5);
+        set.add(5);
+        set.add(9);
+        set.add(5);
+        set.add(7);
+        set.add(1);
+
+        int[] values = { 1, 3, 5, 7, 9 };
+        int[] setvals = set.toIntArray();
+
+        assert("values equal", Arrays.equals(values, setvals));
+    }
+
+    public static Test suite ()
+    {
+        return new ArrayIntSetTest();
+    }
+}