jtulach@1399: /*
jtulach@1399:  * Copyright (c) 1995, 2007, Oracle and/or its affiliates. All rights reserved.
jtulach@1399:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jtulach@1399:  *
jtulach@1399:  * This code is free software; you can redistribute it and/or modify it
jtulach@1399:  * under the terms of the GNU General Public License version 2 only, as
jtulach@1399:  * published by the Free Software Foundation.  Oracle designates this
jtulach@1399:  * particular file as subject to the "Classpath" exception as provided
jtulach@1399:  * by Oracle in the LICENSE file that accompanied this code.
jtulach@1399:  *
jtulach@1399:  * This code is distributed in the hope that it will be useful, but WITHOUT
jtulach@1399:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jtulach@1399:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jtulach@1399:  * version 2 for more details (a copy is included in the LICENSE file that
jtulach@1399:  * accompanied this code).
jtulach@1399:  *
jtulach@1399:  * You should have received a copy of the GNU General Public License version
jtulach@1399:  * 2 along with this work; if not, write to the Free Software Foundation,
jtulach@1399:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jtulach@1399:  *
jtulach@1399:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jtulach@1399:  * or visit www.oracle.com if you need additional information or have any
jtulach@1399:  * questions.
jtulach@1399:  */
jtulach@1399: 
jtulach@1399: package java.util;
jtulach@1399: 
jtulach@1399: import java.io.*;
jtulach@1399: 
jtulach@1399: /**
jtulach@1399:  * This class implements a vector of bits that grows as needed. Each
jtulach@1399:  * component of the bit set has a {@code boolean} value. The
jtulach@1399:  * bits of a {@code BitSet} are indexed by nonnegative integers.
jtulach@1399:  * Individual indexed bits can be examined, set, or cleared. One
jtulach@1399:  * {@code BitSet} may be used to modify the contents of another
jtulach@1399:  * {@code BitSet} through logical AND, logical inclusive OR, and
jtulach@1399:  * logical exclusive OR operations.
jtulach@1399:  *
jtulach@1399:  * <p>By default, all bits in the set initially have the value
jtulach@1399:  * {@code false}.
jtulach@1399:  *
jtulach@1399:  * <p>Every bit set has a current size, which is the number of bits
jtulach@1399:  * of space currently in use by the bit set. Note that the size is
jtulach@1399:  * related to the implementation of a bit set, so it may change with
jtulach@1399:  * implementation. The length of a bit set relates to logical length
jtulach@1399:  * of a bit set and is defined independently of implementation.
jtulach@1399:  *
jtulach@1399:  * <p>Unless otherwise noted, passing a null parameter to any of the
jtulach@1399:  * methods in a {@code BitSet} will result in a
jtulach@1399:  * {@code NullPointerException}.
jtulach@1399:  *
jtulach@1399:  * <p>A {@code BitSet} is not safe for multithreaded use without
jtulach@1399:  * external synchronization.
jtulach@1399:  *
jtulach@1399:  * @author  Arthur van Hoff
jtulach@1399:  * @author  Michael McCloskey
jtulach@1399:  * @author  Martin Buchholz
jtulach@1399:  * @since   JDK1.0
jtulach@1399:  */
jtulach@1399: public class BitSet implements Cloneable, java.io.Serializable {
jtulach@1399:     /*
jtulach@1399:      * BitSets are packed into arrays of "words."  Currently a word is
jtulach@1399:      * a long, which consists of 64 bits, requiring 6 address bits.
jtulach@1399:      * The choice of word size is determined purely by performance concerns.
jtulach@1399:      */
jtulach@1399:     private final static int ADDRESS_BITS_PER_WORD = 6;
jtulach@1399:     private final static int BITS_PER_WORD = 1 << ADDRESS_BITS_PER_WORD;
jtulach@1399:     private final static int BIT_INDEX_MASK = BITS_PER_WORD - 1;
jtulach@1399: 
jtulach@1399:     /* Used to shift left or right for a partial word mask */
jtulach@1399:     private static final long WORD_MASK = 0xffffffffffffffffL;
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * @serialField bits long[]
jtulach@1399:      *
jtulach@1399:      * The bits in this BitSet.  The ith bit is stored in bits[i/64] at
jtulach@1399:      * bit position i % 64 (where bit position 0 refers to the least
jtulach@1399:      * significant bit and 63 refers to the most significant bit).
jtulach@1399:      */
jtulach@1399:     private static final ObjectStreamField[] serialPersistentFields = {
jtulach@1399:         new ObjectStreamField("bits", long[].class),
jtulach@1399:     };
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * The internal field corresponding to the serialField "bits".
jtulach@1399:      */
jtulach@1399:     private long[] words;
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * The number of words in the logical size of this BitSet.
jtulach@1399:      */
jtulach@1399:     private transient int wordsInUse = 0;
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Whether the size of "words" is user-specified.  If so, we assume
jtulach@1399:      * the user knows what he's doing and try harder to preserve it.
jtulach@1399:      */
jtulach@1399:     private transient boolean sizeIsSticky = false;
jtulach@1399: 
jtulach@1399:     /* use serialVersionUID from JDK 1.0.2 for interoperability */
jtulach@1399:     private static final long serialVersionUID = 7997698588986878753L;
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Given a bit index, return word index containing it.
jtulach@1399:      */
jtulach@1399:     private static int wordIndex(int bitIndex) {
jtulach@1399:         return bitIndex >> ADDRESS_BITS_PER_WORD;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Every public method must preserve these invariants.
jtulach@1399:      */
jtulach@1399:     private void checkInvariants() {
jtulach@1399:         assert(wordsInUse == 0 || words[wordsInUse - 1] != 0);
jtulach@1399:         assert(wordsInUse >= 0 && wordsInUse <= words.length);
jtulach@1399:         assert(wordsInUse == words.length || words[wordsInUse] == 0);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the field wordsInUse to the logical size in words of the bit set.
jtulach@1399:      * WARNING:This method assumes that the number of words actually in use is
jtulach@1399:      * less than or equal to the current value of wordsInUse!
jtulach@1399:      */
jtulach@1399:     private void recalculateWordsInUse() {
jtulach@1399:         // Traverse the bitset until a used word is found
jtulach@1399:         int i;
jtulach@1399:         for (i = wordsInUse-1; i >= 0; i--)
jtulach@1399:             if (words[i] != 0)
jtulach@1399:                 break;
jtulach@1399: 
jtulach@1399:         wordsInUse = i+1; // The new logical size
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Creates a new bit set. All bits are initially {@code false}.
jtulach@1399:      */
jtulach@1399:     public BitSet() {
jtulach@1399:         initWords(BITS_PER_WORD);
jtulach@1399:         sizeIsSticky = false;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Creates a bit set whose initial size is large enough to explicitly
jtulach@1399:      * represent bits with indices in the range {@code 0} through
jtulach@1399:      * {@code nbits-1}. All bits are initially {@code false}.
jtulach@1399:      *
jtulach@1399:      * @param  nbits the initial size of the bit set
jtulach@1399:      * @throws NegativeArraySizeException if the specified initial size
jtulach@1399:      *         is negative
jtulach@1399:      */
jtulach@1399:     public BitSet(int nbits) {
jtulach@1399:         // nbits can't be negative; size 0 is OK
jtulach@1399:         if (nbits < 0)
jtulach@1399:             throw new NegativeArraySizeException("nbits < 0: " + nbits);
jtulach@1399: 
jtulach@1399:         initWords(nbits);
jtulach@1399:         sizeIsSticky = true;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     private void initWords(int nbits) {
jtulach@1399:         words = new long[wordIndex(nbits-1) + 1];
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Creates a bit set using words as the internal representation.
jtulach@1399:      * The last word (if there is one) must be non-zero.
jtulach@1399:      */
jtulach@1399:     private BitSet(long[] words) {
jtulach@1399:         this.words = words;
jtulach@1399:         this.wordsInUse = words.length;
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new bit set containing all the bits in the given long array.
jtulach@1399:      *
jtulach@1399:      * <p>More precisely,
jtulach@1399:      * <br>{@code BitSet.valueOf(longs).get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)}
jtulach@1399:      * <br>for all {@code n < 64 * longs.length}.
jtulach@1399:      *
jtulach@1399:      * <p>This method is equivalent to
jtulach@1399:      * {@code BitSet.valueOf(LongBuffer.wrap(longs))}.
jtulach@1399:      *
jtulach@1399:      * @param longs a long array containing a little-endian representation
jtulach@1399:      *        of a sequence of bits to be used as the initial bits of the
jtulach@1399:      *        new bit set
jtulach@1399:      * @since 1.7
jtulach@1399:      */
jtulach@1399:     public static BitSet valueOf(long[] longs) {
jtulach@1399:         int n;
jtulach@1399:         for (n = longs.length; n > 0 && longs[n - 1] == 0; n--)
jtulach@1399:             ;
jtulach@1399:         return new BitSet(Arrays.copyOf(longs, n));
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new bit set containing all the bits in the given long
jtulach@1399:      * buffer between its position and limit.
jtulach@1399:      *
jtulach@1399:      * <p>More precisely,
jtulach@1399:      * <br>{@code BitSet.valueOf(lb).get(n) == ((lb.get(lb.position()+n/64) & (1L<<(n%64))) != 0)}
jtulach@1399:      * <br>for all {@code n < 64 * lb.remaining()}.
jtulach@1399:      *
jtulach@1399:      * <p>The long buffer is not modified by this method, and no
jtulach@1399:      * reference to the buffer is retained by the bit set.
jtulach@1399:      *
jtulach@1399:      * @param lb a long buffer containing a little-endian representation
jtulach@1399:      *        of a sequence of bits between its position and limit, to be
jtulach@1399:      *        used as the initial bits of the new bit set
jtulach@1399:      * @since 1.7
jtulach@1399:      */
jaroslav@1401: //    public static BitSet valueOf(LongBuffer lb) {
jaroslav@1401: //        lb = lb.slice();
jaroslav@1401: //        int n;
jaroslav@1401: //        for (n = lb.remaining(); n > 0 && lb.get(n - 1) == 0; n--)
jaroslav@1401: //            ;
jaroslav@1401: //        long[] words = new long[n];
jaroslav@1401: //        lb.get(words);
jaroslav@1401: //        return new BitSet(words);
jaroslav@1401: //    }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new bit set containing all the bits in the given byte array.
jtulach@1399:      *
jtulach@1399:      * <p>More precisely,
jtulach@1399:      * <br>{@code BitSet.valueOf(bytes).get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)}
jtulach@1399:      * <br>for all {@code n <  8 * bytes.length}.
jtulach@1399:      *
jtulach@1399:      * <p>This method is equivalent to
jtulach@1399:      * {@code BitSet.valueOf(ByteBuffer.wrap(bytes))}.
jtulach@1399:      *
jtulach@1399:      * @param bytes a byte array containing a little-endian
jtulach@1399:      *        representation of a sequence of bits to be used as the
jtulach@1399:      *        initial bits of the new bit set
jtulach@1399:      * @since 1.7
jtulach@1399:      */
jaroslav@1401: //    public static BitSet valueOf(byte[] bytes) {
jaroslav@1401: //        return BitSet.valueOf(ByteBuffer.wrap(bytes));
jaroslav@1401: //    }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new bit set containing all the bits in the given byte
jtulach@1399:      * buffer between its position and limit.
jtulach@1399:      *
jtulach@1399:      * <p>More precisely,
jtulach@1399:      * <br>{@code BitSet.valueOf(bb).get(n) == ((bb.get(bb.position()+n/8) & (1<<(n%8))) != 0)}
jtulach@1399:      * <br>for all {@code n < 8 * bb.remaining()}.
jtulach@1399:      *
jtulach@1399:      * <p>The byte buffer is not modified by this method, and no
jtulach@1399:      * reference to the buffer is retained by the bit set.
jtulach@1399:      *
jtulach@1399:      * @param bb a byte buffer containing a little-endian representation
jtulach@1399:      *        of a sequence of bits between its position and limit, to be
jtulach@1399:      *        used as the initial bits of the new bit set
jtulach@1399:      * @since 1.7
jtulach@1399:      */
jaroslav@1401: //    public static BitSet valueOf(ByteBuffer bb) {
jaroslav@1401: //        bb = bb.slice().order(ByteOrder.LITTLE_ENDIAN);
jaroslav@1401: //        int n;
jaroslav@1401: //        for (n = bb.remaining(); n > 0 && bb.get(n - 1) == 0; n--)
jaroslav@1401: //            ;
jaroslav@1401: //        long[] words = new long[(n + 7) / 8];
jaroslav@1401: //        bb.limit(n);
jaroslav@1401: //        int i = 0;
jaroslav@1401: //        while (bb.remaining() >= 8)
jaroslav@1401: //            words[i++] = bb.getLong();
jaroslav@1401: //        for (int remaining = bb.remaining(), j = 0; j < remaining; j++)
jaroslav@1401: //            words[i] |= (bb.get() & 0xffL) << (8 * j);
jaroslav@1401: //        return new BitSet(words);
jaroslav@1401: //    }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new byte array containing all the bits in this bit set.
jtulach@1399:      *
jtulach@1399:      * <p>More precisely, if
jtulach@1399:      * <br>{@code byte[] bytes = s.toByteArray();}
jtulach@1399:      * <br>then {@code bytes.length == (s.length()+7)/8} and
jtulach@1399:      * <br>{@code s.get(n) == ((bytes[n/8] & (1<<(n%8))) != 0)}
jtulach@1399:      * <br>for all {@code n < 8 * bytes.length}.
jtulach@1399:      *
jtulach@1399:      * @return a byte array containing a little-endian representation
jtulach@1399:      *         of all the bits in this bit set
jtulach@1399:      * @since 1.7
jtulach@1399:     */
jaroslav@1401: //    public byte[] toByteArray() {
jaroslav@1401: //        int n = wordsInUse;
jaroslav@1401: //        if (n == 0)
jaroslav@1401: //            return new byte[0];
jaroslav@1401: //        int len = 8 * (n-1);
jaroslav@1401: //        for (long x = words[n - 1]; x != 0; x >>>= 8)
jaroslav@1401: //            len++;
jaroslav@1401: //        byte[] bytes = new byte[len];
jaroslav@1401: //        ByteBuffer bb = ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN);
jaroslav@1401: //        for (int i = 0; i < n - 1; i++)
jaroslav@1401: //            bb.putLong(words[i]);
jaroslav@1401: //        for (long x = words[n - 1]; x != 0; x >>>= 8)
jaroslav@1401: //            bb.put((byte) (x & 0xff));
jaroslav@1401: //        return bytes;
jaroslav@1401: //    }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new long array containing all the bits in this bit set.
jtulach@1399:      *
jtulach@1399:      * <p>More precisely, if
jtulach@1399:      * <br>{@code long[] longs = s.toLongArray();}
jtulach@1399:      * <br>then {@code longs.length == (s.length()+63)/64} and
jtulach@1399:      * <br>{@code s.get(n) == ((longs[n/64] & (1L<<(n%64))) != 0)}
jtulach@1399:      * <br>for all {@code n < 64 * longs.length}.
jtulach@1399:      *
jtulach@1399:      * @return a long array containing a little-endian representation
jtulach@1399:      *         of all the bits in this bit set
jtulach@1399:      * @since 1.7
jtulach@1399:     */
jtulach@1399:     public long[] toLongArray() {
jtulach@1399:         return Arrays.copyOf(words, wordsInUse);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Ensures that the BitSet can hold enough words.
jtulach@1399:      * @param wordsRequired the minimum acceptable number of words.
jtulach@1399:      */
jtulach@1399:     private void ensureCapacity(int wordsRequired) {
jtulach@1399:         if (words.length < wordsRequired) {
jtulach@1399:             // Allocate larger of doubled size or required size
jtulach@1399:             int request = Math.max(2 * words.length, wordsRequired);
jtulach@1399:             words = Arrays.copyOf(words, request);
jtulach@1399:             sizeIsSticky = false;
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Ensures that the BitSet can accommodate a given wordIndex,
jtulach@1399:      * temporarily violating the invariants.  The caller must
jtulach@1399:      * restore the invariants before returning to the user,
jtulach@1399:      * possibly using recalculateWordsInUse().
jtulach@1399:      * @param wordIndex the index to be accommodated.
jtulach@1399:      */
jtulach@1399:     private void expandTo(int wordIndex) {
jtulach@1399:         int wordsRequired = wordIndex+1;
jtulach@1399:         if (wordsInUse < wordsRequired) {
jtulach@1399:             ensureCapacity(wordsRequired);
jtulach@1399:             wordsInUse = wordsRequired;
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Checks that fromIndex ... toIndex is a valid range of bit indices.
jtulach@1399:      */
jtulach@1399:     private static void checkRange(int fromIndex, int toIndex) {
jtulach@1399:         if (fromIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("fromIndex < 0: " + fromIndex);
jtulach@1399:         if (toIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("toIndex < 0: " + toIndex);
jtulach@1399:         if (fromIndex > toIndex)
jtulach@1399:             throw new IndexOutOfBoundsException("fromIndex: " + fromIndex +
jtulach@1399:                                                 " > toIndex: " + toIndex);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bit at the specified index to the complement of its
jtulach@1399:      * current value.
jtulach@1399:      *
jtulach@1399:      * @param  bitIndex the index of the bit to flip
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public void flip(int bitIndex) {
jtulach@1399:         if (bitIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex);
jtulach@1399: 
jtulach@1399:         int wordIndex = wordIndex(bitIndex);
jtulach@1399:         expandTo(wordIndex);
jtulach@1399: 
jtulach@1399:         words[wordIndex] ^= (1L << bitIndex);
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets each bit from the specified {@code fromIndex} (inclusive) to the
jtulach@1399:      * specified {@code toIndex} (exclusive) to the complement of its current
jtulach@1399:      * value.
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex index of the first bit to flip
jtulach@1399:      * @param  toIndex index after the last bit to flip
jtulach@1399:      * @throws IndexOutOfBoundsException if {@code fromIndex} is negative,
jtulach@1399:      *         or {@code toIndex} is negative, or {@code fromIndex} is
jtulach@1399:      *         larger than {@code toIndex}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public void flip(int fromIndex, int toIndex) {
jtulach@1399:         checkRange(fromIndex, toIndex);
jtulach@1399: 
jtulach@1399:         if (fromIndex == toIndex)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         int startWordIndex = wordIndex(fromIndex);
jtulach@1399:         int endWordIndex   = wordIndex(toIndex - 1);
jtulach@1399:         expandTo(endWordIndex);
jtulach@1399: 
jtulach@1399:         long firstWordMask = WORD_MASK << fromIndex;
jtulach@1399:         long lastWordMask  = WORD_MASK >>> -toIndex;
jtulach@1399:         if (startWordIndex == endWordIndex) {
jtulach@1399:             // Case 1: One word
jtulach@1399:             words[startWordIndex] ^= (firstWordMask & lastWordMask);
jtulach@1399:         } else {
jtulach@1399:             // Case 2: Multiple words
jtulach@1399:             // Handle first word
jtulach@1399:             words[startWordIndex] ^= firstWordMask;
jtulach@1399: 
jtulach@1399:             // Handle intermediate words, if any
jtulach@1399:             for (int i = startWordIndex+1; i < endWordIndex; i++)
jtulach@1399:                 words[i] ^= WORD_MASK;
jtulach@1399: 
jtulach@1399:             // Handle last word
jtulach@1399:             words[endWordIndex] ^= lastWordMask;
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bit at the specified index to {@code true}.
jtulach@1399:      *
jtulach@1399:      * @param  bitIndex a bit index
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      * @since  JDK1.0
jtulach@1399:      */
jtulach@1399:     public void set(int bitIndex) {
jtulach@1399:         if (bitIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex);
jtulach@1399: 
jtulach@1399:         int wordIndex = wordIndex(bitIndex);
jtulach@1399:         expandTo(wordIndex);
jtulach@1399: 
jtulach@1399:         words[wordIndex] |= (1L << bitIndex); // Restores invariants
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bit at the specified index to the specified value.
jtulach@1399:      *
jtulach@1399:      * @param  bitIndex a bit index
jtulach@1399:      * @param  value a boolean value to set
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public void set(int bitIndex, boolean value) {
jtulach@1399:         if (value)
jtulach@1399:             set(bitIndex);
jtulach@1399:         else
jtulach@1399:             clear(bitIndex);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bits from the specified {@code fromIndex} (inclusive) to the
jtulach@1399:      * specified {@code toIndex} (exclusive) to {@code true}.
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex index of the first bit to be set
jtulach@1399:      * @param  toIndex index after the last bit to be set
jtulach@1399:      * @throws IndexOutOfBoundsException if {@code fromIndex} is negative,
jtulach@1399:      *         or {@code toIndex} is negative, or {@code fromIndex} is
jtulach@1399:      *         larger than {@code toIndex}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public void set(int fromIndex, int toIndex) {
jtulach@1399:         checkRange(fromIndex, toIndex);
jtulach@1399: 
jtulach@1399:         if (fromIndex == toIndex)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         // Increase capacity if necessary
jtulach@1399:         int startWordIndex = wordIndex(fromIndex);
jtulach@1399:         int endWordIndex   = wordIndex(toIndex - 1);
jtulach@1399:         expandTo(endWordIndex);
jtulach@1399: 
jtulach@1399:         long firstWordMask = WORD_MASK << fromIndex;
jtulach@1399:         long lastWordMask  = WORD_MASK >>> -toIndex;
jtulach@1399:         if (startWordIndex == endWordIndex) {
jtulach@1399:             // Case 1: One word
jtulach@1399:             words[startWordIndex] |= (firstWordMask & lastWordMask);
jtulach@1399:         } else {
jtulach@1399:             // Case 2: Multiple words
jtulach@1399:             // Handle first word
jtulach@1399:             words[startWordIndex] |= firstWordMask;
jtulach@1399: 
jtulach@1399:             // Handle intermediate words, if any
jtulach@1399:             for (int i = startWordIndex+1; i < endWordIndex; i++)
jtulach@1399:                 words[i] = WORD_MASK;
jtulach@1399: 
jtulach@1399:             // Handle last word (restores invariants)
jtulach@1399:             words[endWordIndex] |= lastWordMask;
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bits from the specified {@code fromIndex} (inclusive) to the
jtulach@1399:      * specified {@code toIndex} (exclusive) to the specified value.
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex index of the first bit to be set
jtulach@1399:      * @param  toIndex index after the last bit to be set
jtulach@1399:      * @param  value value to set the selected bits to
jtulach@1399:      * @throws IndexOutOfBoundsException if {@code fromIndex} is negative,
jtulach@1399:      *         or {@code toIndex} is negative, or {@code fromIndex} is
jtulach@1399:      *         larger than {@code toIndex}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public void set(int fromIndex, int toIndex, boolean value) {
jtulach@1399:         if (value)
jtulach@1399:             set(fromIndex, toIndex);
jtulach@1399:         else
jtulach@1399:             clear(fromIndex, toIndex);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bit specified by the index to {@code false}.
jtulach@1399:      *
jtulach@1399:      * @param  bitIndex the index of the bit to be cleared
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      * @since  JDK1.0
jtulach@1399:      */
jtulach@1399:     public void clear(int bitIndex) {
jtulach@1399:         if (bitIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex);
jtulach@1399: 
jtulach@1399:         int wordIndex = wordIndex(bitIndex);
jtulach@1399:         if (wordIndex >= wordsInUse)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         words[wordIndex] &= ~(1L << bitIndex);
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets the bits from the specified {@code fromIndex} (inclusive) to the
jtulach@1399:      * specified {@code toIndex} (exclusive) to {@code false}.
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex index of the first bit to be cleared
jtulach@1399:      * @param  toIndex index after the last bit to be cleared
jtulach@1399:      * @throws IndexOutOfBoundsException if {@code fromIndex} is negative,
jtulach@1399:      *         or {@code toIndex} is negative, or {@code fromIndex} is
jtulach@1399:      *         larger than {@code toIndex}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public void clear(int fromIndex, int toIndex) {
jtulach@1399:         checkRange(fromIndex, toIndex);
jtulach@1399: 
jtulach@1399:         if (fromIndex == toIndex)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         int startWordIndex = wordIndex(fromIndex);
jtulach@1399:         if (startWordIndex >= wordsInUse)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         int endWordIndex = wordIndex(toIndex - 1);
jtulach@1399:         if (endWordIndex >= wordsInUse) {
jtulach@1399:             toIndex = length();
jtulach@1399:             endWordIndex = wordsInUse - 1;
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         long firstWordMask = WORD_MASK << fromIndex;
jtulach@1399:         long lastWordMask  = WORD_MASK >>> -toIndex;
jtulach@1399:         if (startWordIndex == endWordIndex) {
jtulach@1399:             // Case 1: One word
jtulach@1399:             words[startWordIndex] &= ~(firstWordMask & lastWordMask);
jtulach@1399:         } else {
jtulach@1399:             // Case 2: Multiple words
jtulach@1399:             // Handle first word
jtulach@1399:             words[startWordIndex] &= ~firstWordMask;
jtulach@1399: 
jtulach@1399:             // Handle intermediate words, if any
jtulach@1399:             for (int i = startWordIndex+1; i < endWordIndex; i++)
jtulach@1399:                 words[i] = 0;
jtulach@1399: 
jtulach@1399:             // Handle last word
jtulach@1399:             words[endWordIndex] &= ~lastWordMask;
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Sets all of the bits in this BitSet to {@code false}.
jtulach@1399:      *
jtulach@1399:      * @since 1.4
jtulach@1399:      */
jtulach@1399:     public void clear() {
jtulach@1399:         while (wordsInUse > 0)
jtulach@1399:             words[--wordsInUse] = 0;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the value of the bit with the specified index. The value
jtulach@1399:      * is {@code true} if the bit with the index {@code bitIndex}
jtulach@1399:      * is currently set in this {@code BitSet}; otherwise, the result
jtulach@1399:      * is {@code false}.
jtulach@1399:      *
jtulach@1399:      * @param  bitIndex   the bit index
jtulach@1399:      * @return the value of the bit with the specified index
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      */
jtulach@1399:     public boolean get(int bitIndex) {
jtulach@1399:         if (bitIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("bitIndex < 0: " + bitIndex);
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int wordIndex = wordIndex(bitIndex);
jtulach@1399:         return (wordIndex < wordsInUse)
jtulach@1399:             && ((words[wordIndex] & (1L << bitIndex)) != 0);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a new {@code BitSet} composed of bits from this {@code BitSet}
jtulach@1399:      * from {@code fromIndex} (inclusive) to {@code toIndex} (exclusive).
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex index of the first bit to include
jtulach@1399:      * @param  toIndex index after the last bit to include
jtulach@1399:      * @return a new {@code BitSet} from a range of this {@code BitSet}
jtulach@1399:      * @throws IndexOutOfBoundsException if {@code fromIndex} is negative,
jtulach@1399:      *         or {@code toIndex} is negative, or {@code fromIndex} is
jtulach@1399:      *         larger than {@code toIndex}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public BitSet get(int fromIndex, int toIndex) {
jtulach@1399:         checkRange(fromIndex, toIndex);
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int len = length();
jtulach@1399: 
jtulach@1399:         // If no set bits in range return empty bitset
jtulach@1399:         if (len <= fromIndex || fromIndex == toIndex)
jtulach@1399:             return new BitSet(0);
jtulach@1399: 
jtulach@1399:         // An optimization
jtulach@1399:         if (toIndex > len)
jtulach@1399:             toIndex = len;
jtulach@1399: 
jtulach@1399:         BitSet result = new BitSet(toIndex - fromIndex);
jtulach@1399:         int targetWords = wordIndex(toIndex - fromIndex - 1) + 1;
jtulach@1399:         int sourceIndex = wordIndex(fromIndex);
jtulach@1399:         boolean wordAligned = ((fromIndex & BIT_INDEX_MASK) == 0);
jtulach@1399: 
jtulach@1399:         // Process all words but the last word
jtulach@1399:         for (int i = 0; i < targetWords - 1; i++, sourceIndex++)
jtulach@1399:             result.words[i] = wordAligned ? words[sourceIndex] :
jtulach@1399:                 (words[sourceIndex] >>> fromIndex) |
jtulach@1399:                 (words[sourceIndex+1] << -fromIndex);
jtulach@1399: 
jtulach@1399:         // Process the last word
jtulach@1399:         long lastWordMask = WORD_MASK >>> -toIndex;
jtulach@1399:         result.words[targetWords - 1] =
jtulach@1399:             ((toIndex-1) & BIT_INDEX_MASK) < (fromIndex & BIT_INDEX_MASK)
jtulach@1399:             ? /* straddles source words */
jtulach@1399:             ((words[sourceIndex] >>> fromIndex) |
jtulach@1399:              (words[sourceIndex+1] & lastWordMask) << -fromIndex)
jtulach@1399:             :
jtulach@1399:             ((words[sourceIndex] & lastWordMask) >>> fromIndex);
jtulach@1399: 
jtulach@1399:         // Set wordsInUse correctly
jtulach@1399:         result.wordsInUse = targetWords;
jtulach@1399:         result.recalculateWordsInUse();
jtulach@1399:         result.checkInvariants();
jtulach@1399: 
jtulach@1399:         return result;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the index of the first bit that is set to {@code true}
jtulach@1399:      * that occurs on or after the specified starting index. If no such
jtulach@1399:      * bit exists then {@code -1} is returned.
jtulach@1399:      *
jtulach@1399:      * <p>To iterate over the {@code true} bits in a {@code BitSet},
jtulach@1399:      * use the following loop:
jtulach@1399:      *
jtulach@1399:      *  <pre> {@code
jtulach@1399:      * for (int i = bs.nextSetBit(0); i >= 0; i = bs.nextSetBit(i+1)) {
jtulach@1399:      *     // operate on index i here
jtulach@1399:      * }}</pre>
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex the index to start checking from (inclusive)
jtulach@1399:      * @return the index of the next set bit, or {@code -1} if there
jtulach@1399:      *         is no such bit
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public int nextSetBit(int fromIndex) {
jtulach@1399:         if (fromIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("fromIndex < 0: " + fromIndex);
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int u = wordIndex(fromIndex);
jtulach@1399:         if (u >= wordsInUse)
jtulach@1399:             return -1;
jtulach@1399: 
jtulach@1399:         long word = words[u] & (WORD_MASK << fromIndex);
jtulach@1399: 
jtulach@1399:         while (true) {
jtulach@1399:             if (word != 0)
jtulach@1399:                 return (u * BITS_PER_WORD) + Long.numberOfTrailingZeros(word);
jtulach@1399:             if (++u == wordsInUse)
jtulach@1399:                 return -1;
jtulach@1399:             word = words[u];
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the index of the first bit that is set to {@code false}
jtulach@1399:      * that occurs on or after the specified starting index.
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex the index to start checking from (inclusive)
jtulach@1399:      * @return the index of the next clear bit
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is negative
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public int nextClearBit(int fromIndex) {
jtulach@1399:         // Neither spec nor implementation handle bitsets of maximal length.
jtulach@1399:         // See 4816253.
jtulach@1399:         if (fromIndex < 0)
jtulach@1399:             throw new IndexOutOfBoundsException("fromIndex < 0: " + fromIndex);
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int u = wordIndex(fromIndex);
jtulach@1399:         if (u >= wordsInUse)
jtulach@1399:             return fromIndex;
jtulach@1399: 
jtulach@1399:         long word = ~words[u] & (WORD_MASK << fromIndex);
jtulach@1399: 
jtulach@1399:         while (true) {
jtulach@1399:             if (word != 0)
jtulach@1399:                 return (u * BITS_PER_WORD) + Long.numberOfTrailingZeros(word);
jtulach@1399:             if (++u == wordsInUse)
jtulach@1399:                 return wordsInUse * BITS_PER_WORD;
jtulach@1399:             word = ~words[u];
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the index of the nearest bit that is set to {@code true}
jtulach@1399:      * that occurs on or before the specified starting index.
jtulach@1399:      * If no such bit exists, or if {@code -1} is given as the
jtulach@1399:      * starting index, then {@code -1} is returned.
jtulach@1399:      *
jtulach@1399:      * <p>To iterate over the {@code true} bits in a {@code BitSet},
jtulach@1399:      * use the following loop:
jtulach@1399:      *
jtulach@1399:      *  <pre> {@code
jtulach@1399:      * for (int i = bs.length(); (i = bs.previousSetBit(i-1)) >= 0; ) {
jtulach@1399:      *     // operate on index i here
jtulach@1399:      * }}</pre>
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex the index to start checking from (inclusive)
jtulach@1399:      * @return the index of the previous set bit, or {@code -1} if there
jtulach@1399:      *         is no such bit
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is less
jtulach@1399:      *         than {@code -1}
jtulach@1399:      * @since  1.7
jtulach@1399:      */
jtulach@1399:     public int previousSetBit(int fromIndex) {
jtulach@1399:         if (fromIndex < 0) {
jtulach@1399:             if (fromIndex == -1)
jtulach@1399:                 return -1;
jtulach@1399:             throw new IndexOutOfBoundsException(
jtulach@1399:                 "fromIndex < -1: " + fromIndex);
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int u = wordIndex(fromIndex);
jtulach@1399:         if (u >= wordsInUse)
jtulach@1399:             return length() - 1;
jtulach@1399: 
jtulach@1399:         long word = words[u] & (WORD_MASK >>> -(fromIndex+1));
jtulach@1399: 
jtulach@1399:         while (true) {
jtulach@1399:             if (word != 0)
jtulach@1399:                 return (u+1) * BITS_PER_WORD - 1 - Long.numberOfLeadingZeros(word);
jtulach@1399:             if (u-- == 0)
jtulach@1399:                 return -1;
jtulach@1399:             word = words[u];
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the index of the nearest bit that is set to {@code false}
jtulach@1399:      * that occurs on or before the specified starting index.
jtulach@1399:      * If no such bit exists, or if {@code -1} is given as the
jtulach@1399:      * starting index, then {@code -1} is returned.
jtulach@1399:      *
jtulach@1399:      * @param  fromIndex the index to start checking from (inclusive)
jtulach@1399:      * @return the index of the previous clear bit, or {@code -1} if there
jtulach@1399:      *         is no such bit
jtulach@1399:      * @throws IndexOutOfBoundsException if the specified index is less
jtulach@1399:      *         than {@code -1}
jtulach@1399:      * @since  1.7
jtulach@1399:      */
jtulach@1399:     public int previousClearBit(int fromIndex) {
jtulach@1399:         if (fromIndex < 0) {
jtulach@1399:             if (fromIndex == -1)
jtulach@1399:                 return -1;
jtulach@1399:             throw new IndexOutOfBoundsException(
jtulach@1399:                 "fromIndex < -1: " + fromIndex);
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int u = wordIndex(fromIndex);
jtulach@1399:         if (u >= wordsInUse)
jtulach@1399:             return fromIndex;
jtulach@1399: 
jtulach@1399:         long word = ~words[u] & (WORD_MASK >>> -(fromIndex+1));
jtulach@1399: 
jtulach@1399:         while (true) {
jtulach@1399:             if (word != 0)
jtulach@1399:                 return (u+1) * BITS_PER_WORD -1 - Long.numberOfLeadingZeros(word);
jtulach@1399:             if (u-- == 0)
jtulach@1399:                 return -1;
jtulach@1399:             word = ~words[u];
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the "logical size" of this {@code BitSet}: the index of
jtulach@1399:      * the highest set bit in the {@code BitSet} plus one. Returns zero
jtulach@1399:      * if the {@code BitSet} contains no set bits.
jtulach@1399:      *
jtulach@1399:      * @return the logical size of this {@code BitSet}
jtulach@1399:      * @since  1.2
jtulach@1399:      */
jtulach@1399:     public int length() {
jtulach@1399:         if (wordsInUse == 0)
jtulach@1399:             return 0;
jtulach@1399: 
jtulach@1399:         return BITS_PER_WORD * (wordsInUse - 1) +
jtulach@1399:             (BITS_PER_WORD - Long.numberOfLeadingZeros(words[wordsInUse - 1]));
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns true if this {@code BitSet} contains no bits that are set
jtulach@1399:      * to {@code true}.
jtulach@1399:      *
jtulach@1399:      * @return boolean indicating whether this {@code BitSet} is empty
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public boolean isEmpty() {
jtulach@1399:         return wordsInUse == 0;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns true if the specified {@code BitSet} has any bits set to
jtulach@1399:      * {@code true} that are also set to {@code true} in this {@code BitSet}.
jtulach@1399:      *
jtulach@1399:      * @param  set {@code BitSet} to intersect with
jtulach@1399:      * @return boolean indicating whether this {@code BitSet} intersects
jtulach@1399:      *         the specified {@code BitSet}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public boolean intersects(BitSet set) {
jtulach@1399:         for (int i = Math.min(wordsInUse, set.wordsInUse) - 1; i >= 0; i--)
jtulach@1399:             if ((words[i] & set.words[i]) != 0)
jtulach@1399:                 return true;
jtulach@1399:         return false;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the number of bits set to {@code true} in this {@code BitSet}.
jtulach@1399:      *
jtulach@1399:      * @return the number of bits set to {@code true} in this {@code BitSet}
jtulach@1399:      * @since  1.4
jtulach@1399:      */
jtulach@1399:     public int cardinality() {
jtulach@1399:         int sum = 0;
jtulach@1399:         for (int i = 0; i < wordsInUse; i++)
jtulach@1399:             sum += Long.bitCount(words[i]);
jtulach@1399:         return sum;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Performs a logical <b>AND</b> of this target bit set with the
jtulach@1399:      * argument bit set. This bit set is modified so that each bit in it
jtulach@1399:      * has the value {@code true} if and only if it both initially
jtulach@1399:      * had the value {@code true} and the corresponding bit in the
jtulach@1399:      * bit set argument also had the value {@code true}.
jtulach@1399:      *
jtulach@1399:      * @param set a bit set
jtulach@1399:      */
jtulach@1399:     public void and(BitSet set) {
jtulach@1399:         if (this == set)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         while (wordsInUse > set.wordsInUse)
jtulach@1399:             words[--wordsInUse] = 0;
jtulach@1399: 
jtulach@1399:         // Perform logical AND on words in common
jtulach@1399:         for (int i = 0; i < wordsInUse; i++)
jtulach@1399:             words[i] &= set.words[i];
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Performs a logical <b>OR</b> of this bit set with the bit set
jtulach@1399:      * argument. This bit set is modified so that a bit in it has the
jtulach@1399:      * value {@code true} if and only if it either already had the
jtulach@1399:      * value {@code true} or the corresponding bit in the bit set
jtulach@1399:      * argument has the value {@code true}.
jtulach@1399:      *
jtulach@1399:      * @param set a bit set
jtulach@1399:      */
jtulach@1399:     public void or(BitSet set) {
jtulach@1399:         if (this == set)
jtulach@1399:             return;
jtulach@1399: 
jtulach@1399:         int wordsInCommon = Math.min(wordsInUse, set.wordsInUse);
jtulach@1399: 
jtulach@1399:         if (wordsInUse < set.wordsInUse) {
jtulach@1399:             ensureCapacity(set.wordsInUse);
jtulach@1399:             wordsInUse = set.wordsInUse;
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         // Perform logical OR on words in common
jtulach@1399:         for (int i = 0; i < wordsInCommon; i++)
jtulach@1399:             words[i] |= set.words[i];
jtulach@1399: 
jtulach@1399:         // Copy any remaining words
jtulach@1399:         if (wordsInCommon < set.wordsInUse)
jtulach@1399:             System.arraycopy(set.words, wordsInCommon,
jtulach@1399:                              words, wordsInCommon,
jtulach@1399:                              wordsInUse - wordsInCommon);
jtulach@1399: 
jtulach@1399:         // recalculateWordsInUse() is unnecessary
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Performs a logical <b>XOR</b> of this bit set with the bit set
jtulach@1399:      * argument. This bit set is modified so that a bit in it has the
jtulach@1399:      * value {@code true} if and only if one of the following
jtulach@1399:      * statements holds:
jtulach@1399:      * <ul>
jtulach@1399:      * <li>The bit initially has the value {@code true}, and the
jtulach@1399:      *     corresponding bit in the argument has the value {@code false}.
jtulach@1399:      * <li>The bit initially has the value {@code false}, and the
jtulach@1399:      *     corresponding bit in the argument has the value {@code true}.
jtulach@1399:      * </ul>
jtulach@1399:      *
jtulach@1399:      * @param  set a bit set
jtulach@1399:      */
jtulach@1399:     public void xor(BitSet set) {
jtulach@1399:         int wordsInCommon = Math.min(wordsInUse, set.wordsInUse);
jtulach@1399: 
jtulach@1399:         if (wordsInUse < set.wordsInUse) {
jtulach@1399:             ensureCapacity(set.wordsInUse);
jtulach@1399:             wordsInUse = set.wordsInUse;
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         // Perform logical XOR on words in common
jtulach@1399:         for (int i = 0; i < wordsInCommon; i++)
jtulach@1399:             words[i] ^= set.words[i];
jtulach@1399: 
jtulach@1399:         // Copy any remaining words
jtulach@1399:         if (wordsInCommon < set.wordsInUse)
jtulach@1399:             System.arraycopy(set.words, wordsInCommon,
jtulach@1399:                              words, wordsInCommon,
jtulach@1399:                              set.wordsInUse - wordsInCommon);
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Clears all of the bits in this {@code BitSet} whose corresponding
jtulach@1399:      * bit is set in the specified {@code BitSet}.
jtulach@1399:      *
jtulach@1399:      * @param  set the {@code BitSet} with which to mask this
jtulach@1399:      *         {@code BitSet}
jtulach@1399:      * @since  1.2
jtulach@1399:      */
jtulach@1399:     public void andNot(BitSet set) {
jtulach@1399:         // Perform logical (a & !b) on words in common
jtulach@1399:         for (int i = Math.min(wordsInUse, set.wordsInUse) - 1; i >= 0; i--)
jtulach@1399:             words[i] &= ~set.words[i];
jtulach@1399: 
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the hash code value for this bit set. The hash code depends
jtulach@1399:      * only on which bits are set within this {@code BitSet}.
jtulach@1399:      *
jtulach@1399:      * <p>The hash code is defined to be the result of the following
jtulach@1399:      * calculation:
jtulach@1399:      *  <pre> {@code
jtulach@1399:      * public int hashCode() {
jtulach@1399:      *     long h = 1234;
jtulach@1399:      *     long[] words = toLongArray();
jtulach@1399:      *     for (int i = words.length; --i >= 0; )
jtulach@1399:      *         h ^= words[i] * (i + 1);
jtulach@1399:      *     return (int)((h >> 32) ^ h);
jtulach@1399:      * }}</pre>
jtulach@1399:      * Note that the hash code changes if the set of bits is altered.
jtulach@1399:      *
jtulach@1399:      * @return the hash code value for this bit set
jtulach@1399:      */
jtulach@1399:     public int hashCode() {
jtulach@1399:         long h = 1234;
jtulach@1399:         for (int i = wordsInUse; --i >= 0; )
jtulach@1399:             h ^= words[i] * (i + 1);
jtulach@1399: 
jtulach@1399:         return (int)((h >> 32) ^ h);
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns the number of bits of space actually in use by this
jtulach@1399:      * {@code BitSet} to represent bit values.
jtulach@1399:      * The maximum element in the set is the size - 1st element.
jtulach@1399:      *
jtulach@1399:      * @return the number of bits currently in this bit set
jtulach@1399:      */
jtulach@1399:     public int size() {
jtulach@1399:         return words.length * BITS_PER_WORD;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Compares this object against the specified object.
jtulach@1399:      * The result is {@code true} if and only if the argument is
jtulach@1399:      * not {@code null} and is a {@code Bitset} object that has
jtulach@1399:      * exactly the same set of bits set to {@code true} as this bit
jtulach@1399:      * set. That is, for every nonnegative {@code int} index {@code k},
jtulach@1399:      * <pre>((BitSet)obj).get(k) == this.get(k)</pre>
jtulach@1399:      * must be true. The current sizes of the two bit sets are not compared.
jtulach@1399:      *
jtulach@1399:      * @param  obj the object to compare with
jtulach@1399:      * @return {@code true} if the objects are the same;
jtulach@1399:      *         {@code false} otherwise
jtulach@1399:      * @see    #size()
jtulach@1399:      */
jtulach@1399:     public boolean equals(Object obj) {
jtulach@1399:         if (!(obj instanceof BitSet))
jtulach@1399:             return false;
jtulach@1399:         if (this == obj)
jtulach@1399:             return true;
jtulach@1399: 
jtulach@1399:         BitSet set = (BitSet) obj;
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399:         set.checkInvariants();
jtulach@1399: 
jtulach@1399:         if (wordsInUse != set.wordsInUse)
jtulach@1399:             return false;
jtulach@1399: 
jtulach@1399:         // Check words in use by both BitSets
jtulach@1399:         for (int i = 0; i < wordsInUse; i++)
jtulach@1399:             if (words[i] != set.words[i])
jtulach@1399:                 return false;
jtulach@1399: 
jtulach@1399:         return true;
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Cloning this {@code BitSet} produces a new {@code BitSet}
jtulach@1399:      * that is equal to it.
jtulach@1399:      * The clone of the bit set is another bit set that has exactly the
jtulach@1399:      * same bits set to {@code true} as this bit set.
jtulach@1399:      *
jtulach@1399:      * @return a clone of this bit set
jtulach@1399:      * @see    #size()
jtulach@1399:      */
jtulach@1399:     public Object clone() {
jtulach@1399:         if (! sizeIsSticky)
jtulach@1399:             trimToSize();
jtulach@1399: 
jtulach@1399:         try {
jtulach@1399:             BitSet result = (BitSet) super.clone();
jtulach@1399:             result.words = words.clone();
jtulach@1399:             result.checkInvariants();
jtulach@1399:             return result;
jtulach@1399:         } catch (CloneNotSupportedException e) {
jtulach@1399:             throw new InternalError();
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Attempts to reduce internal storage used for the bits in this bit set.
jtulach@1399:      * Calling this method may, but is not required to, affect the value
jtulach@1399:      * returned by a subsequent call to the {@link #size()} method.
jtulach@1399:      */
jtulach@1399:     private void trimToSize() {
jtulach@1399:         if (wordsInUse != words.length) {
jtulach@1399:             words = Arrays.copyOf(words, wordsInUse);
jtulach@1399:             checkInvariants();
jtulach@1399:         }
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Save the state of the {@code BitSet} instance to a stream (i.e.,
jtulach@1399:      * serialize it).
jtulach@1399:      */
jtulach@1399:     private void writeObject(ObjectOutputStream s)
jtulach@1399:         throws IOException {
jtulach@1399: 
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         if (! sizeIsSticky)
jtulach@1399:             trimToSize();
jtulach@1399: 
jtulach@1399:         ObjectOutputStream.PutField fields = s.putFields();
jtulach@1399:         fields.put("bits", words);
jtulach@1399:         s.writeFields();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Reconstitute the {@code BitSet} instance from a stream (i.e.,
jtulach@1399:      * deserialize it).
jtulach@1399:      */
jtulach@1399:     private void readObject(ObjectInputStream s)
jtulach@1399:         throws IOException, ClassNotFoundException {
jtulach@1399: 
jtulach@1399:         ObjectInputStream.GetField fields = s.readFields();
jtulach@1399:         words = (long[]) fields.get("bits", null);
jtulach@1399: 
jtulach@1399:         // Assume maximum length then find real length
jtulach@1399:         // because recalculateWordsInUse assumes maintenance
jtulach@1399:         // or reduction in logical size
jtulach@1399:         wordsInUse = words.length;
jtulach@1399:         recalculateWordsInUse();
jtulach@1399:         sizeIsSticky = (words.length > 0 && words[words.length-1] == 0L); // heuristic
jtulach@1399:         checkInvariants();
jtulach@1399:     }
jtulach@1399: 
jtulach@1399:     /**
jtulach@1399:      * Returns a string representation of this bit set. For every index
jtulach@1399:      * for which this {@code BitSet} contains a bit in the set
jtulach@1399:      * state, the decimal representation of that index is included in
jtulach@1399:      * the result. Such indices are listed in order from lowest to
jtulach@1399:      * highest, separated by ",&nbsp;" (a comma and a space) and
jtulach@1399:      * surrounded by braces, resulting in the usual mathematical
jtulach@1399:      * notation for a set of integers.
jtulach@1399:      *
jtulach@1399:      * <p>Example:
jtulach@1399:      * <pre>
jtulach@1399:      * BitSet drPepper = new BitSet();</pre>
jtulach@1399:      * Now {@code drPepper.toString()} returns "{@code {}}".<p>
jtulach@1399:      * <pre>
jtulach@1399:      * drPepper.set(2);</pre>
jtulach@1399:      * Now {@code drPepper.toString()} returns "{@code {2}}".<p>
jtulach@1399:      * <pre>
jtulach@1399:      * drPepper.set(4);
jtulach@1399:      * drPepper.set(10);</pre>
jtulach@1399:      * Now {@code drPepper.toString()} returns "{@code {2, 4, 10}}".
jtulach@1399:      *
jtulach@1399:      * @return a string representation of this bit set
jtulach@1399:      */
jtulach@1399:     public String toString() {
jtulach@1399:         checkInvariants();
jtulach@1399: 
jtulach@1399:         int numBits = (wordsInUse > 128) ?
jtulach@1399:             cardinality() : wordsInUse * BITS_PER_WORD;
jtulach@1399:         StringBuilder b = new StringBuilder(6*numBits + 2);
jtulach@1399:         b.append('{');
jtulach@1399: 
jtulach@1399:         int i = nextSetBit(0);
jtulach@1399:         if (i != -1) {
jtulach@1399:             b.append(i);
jtulach@1399:             for (i = nextSetBit(i+1); i >= 0; i = nextSetBit(i+1)) {
jtulach@1399:                 int endOfRun = nextClearBit(i);
jtulach@1399:                 do { b.append(", ").append(i); }
jtulach@1399:                 while (++i < endOfRun);
jtulach@1399:             }
jtulach@1399:         }
jtulach@1399: 
jtulach@1399:         b.append('}');
jtulach@1399:         return b.toString();
jtulach@1399:     }
jtulach@1399: }