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// CHECKSTYLE:OFF
package com.zaxxer.sparsebits;
/*- This software is the work of Paladin Software International, Incorporated,
* based upon previous work done for and by Sun Microsystems, Inc. */
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
/**
* This class implements a set of bits that grows as needed. Each bit of the
* bit set represents a boolean value. The values of a
* SparseBitSet are indexed by non-negative integers.
* Individual indexed values may be examined, set, cleared, or modified by
* logical operations. One SparseBitSet or logical value may be
* used to modify the contents of (another) SparseBitSet through
* logical AND, logical inclusive OR, logical exclusive
* OR, and And NOT operations over all or part of the bit sets.
*
* All values in a bit set initially have the value false.
*
* Every bit set has a current size, which is the number of bits of space
* nominally in use by the bit set from the first set bit to just after
* the last set bit. The length of the bit set effectively tells the position
* available after the last bit of the SparseBitSet.
*
* The maximum cardinality of a SparseBitSet is
* Integer.MAX_VALUE, which means the bits of a
* SparseBitSet are labelled
* 0 .. Integer.MAX_VALUE − 1.
* After the last set bit of a SparseBitSet, any attempt to find
* a subsequent bit (nextSetBit()), will return an value of −1.
* If an attempt is made to use nextClearBit(), and all the bits are
* set from the starting position of the search to the bit labelled
* Integer.MAX_VALUE − 1, then similarly −1
* will be returned.
*
* Unless otherwise noted, passing a null parameter to any of the methods in
* a SparseBitSet will result in a
* NullPointerException.
*
* A SparseBitSet is not safe for multi-threaded use without
* external synchronization.
*
* @author Bruce K. Haddon
* @author Arthur van Hoff
* @author Michael McCloskey
* @author Martin Buchholz
* @version 1.0, 2009-03-17
* @since 1.6
*/
public class SparseBitSet implements Cloneable, Serializable
{
/* My apologies for listing all the additional authors, but concepts, code,
and even comments have been re-used in this class definition from code in
the JDK that was written and/or maintained by these people. I owe a debt,
which I acknowledge. But they are in no way responsible for what ever
misuse I have made of their work.
Bruce K. Haddon
The representation of a SparseBitSet is packed into "words", and the words
are stored in arrays which are here referred to as "blocks." Blocks are
accessed by two levels of indirection from the master "level 1" (whole)
set array through second level arrays called "areas" (making the blocks
"level3"). A "word" is a long, consisting of 64 bits, requiring six address
bits to select a bit within a word (and this is considered in places to be
a "level4"). This choice of a long for "word" is determined purely by
performance concerns, and is built into the implementation in a deep way,
because the references to blocks are always of the form "long[]." (This
does not mean that blocks could not be changed to arrays of ints, but it
would take some extensive work.)
The fact that there are three levels is also deeply involved in the
scanning algorithms, meaning that the accesses are always nested three
deep. Again, the change this might be a large amount of work. On the
other hand, these three levels have proven, so far, to provide adequate
speed, and an storage efficient way to deal with sparseness.
For simplicity, the level3 blocks and the level2 areas are always "full"
size, i.e., LENGTH3 and LENGTH2 respectively, and for consistency, the
fourth level is of length LENGTH4. The level1 structure is of variable
length (as this may save scanning several thousand null pointers, and
careful consideration must be taken of this at all times, in particular,
when choosing to increase the size (see resize()). The only place where
this array is reduced in size is when a clone is made, in which case it is
created with the smallest size, and allowed to grow as entries are copied
to it. That all the arrays are kept to power-of-2 sizes is a programming
convenience (permitting shifts and masks).
Whenever possible, a level 3 block that contains no bits (all the words are
zero, is discarded, and its reference is replaced by a null value.
Similarly, level 2 areas that contain only null pointers (to level 3
blocks) are discarded, and their references replaced by null values. This
is the "normalized" condition, but does not have to be nor is strictly
enforced. The operations still work if the representation is partially or
totally "denormalized." In particular, the methods that deal with single
bits (setting, flipping, clearing, etc.) do not attempt to normalize the
set, in the interests of speed. However, when a set is scanned as the
resultant set of some operation, then, in most cases, the set will be
normalized--the exception being level2 areas that are not completly scanned
in a particular pass.
The sizes of the blocks and areas has been the result of some investigation
with varying sizes, and the sizes selected appear to represent a reasonable
"sweet" spot. There is, of course, no guarantee that these are the best
for all possible situations, but, given that not having these the same
for all bit sets would be hopelessly complex (bad enough as is), these
values appear to be a fair compromise. */
/**
* This value controls for format of the toString() output.
* @see #toStringCompaction(int)
*/
protected transient int compactionCount;
/**
* The compaction count default.
*/
static int compactionCountDefault = 2; // Note: this is not final!
/**
* The storage for this SparseBitSet. The ith bit is stored in a word
* represented by a long value, and is at bit position i % 64
* within that word (where bit position 0 refers to the least significant bit
* and 63 refers to the most significant bit).
*
* The words are organized into blocks, and the blocks are accessed by two
* additional levels of array indexing.
*/
protected transient long[][][] bits;
/**
* For the current size of the bits array, this is the maximum possible
* length of the bit set, i.e., the index of the last possible bit, plus one.
* Note: this not the value returned by length().
* @see #resize(int)
* @see #length()
*/
protected transient int bitsLength;
//==============================================================================
// The critical parameters. These are set up so that the compiler may
// pre-compute all the values as compile-time constants.
//==============================================================================
/**
* The number of bits in a long value.
*/
protected static final int LENGTH4 = Long.SIZE;
/**
* The number of bits in a positive integer, and the size of permitted index
* of a bit in the bit set.
*/
protected static final int INDEX_SIZE = Integer.SIZE - 1;
/**
* The label (index) of a bit in the bit set is essentially broken into
* 4 "levels". Respectively (from the least significant end), level4, the
* address within word, the address within a level3 block, the address within
* a level2 area, and the level1 address of that area within the set.
*
* LEVEL4 is the number of bits of the level4 address (number of bits need
* to address the bits in a long)
*/
protected static final int LEVEL4 = 6;
/**
* LEVEL3 is the number of bits of the level3 address.
*/
protected static final int LEVEL3 = 5; // Do not change!
/**
* LEVEL2 is the number of bits of the level2 address.
*/
protected static final int LEVEL2 = 5; // Do not change!
/**
* LEVEL1 is the number of bits of the level1 address.
*/
protected static final int LEVEL1 = INDEX_SIZE - LEVEL2 - LEVEL3 - LEVEL4;
/**
* MAX_LENGTH1 is the maximum number of entries in the level1 set array.
*/
protected static final int MAX_LENGTH1 = 1 << LEVEL1;
/**
* LENGTH2 is the number of entries in the any level2 area.
*/
protected static final int LENGTH2 = 1 << LEVEL2;
/**
* LENGTH3 is the number of entries in the any level3 block.
*/
protected static final int LENGTH3 = 1 << LEVEL3;
/**
* The shift to create the word index. (I.e., move it to the right end)
*/
protected static final int SHIFT3 = LEVEL4;
/**
* MASK3 is the mask to extract the LEVEL3 address from a word index
* (after shifting by SHIFT3).
*/
protected static final int MASK3 = LENGTH3 - 1;
/**
* SHIFT2 is the shift to bring the level2 address (from the word index) to
* the right end (i.e., after shifting by SHIFT3).
*/
protected static final int SHIFT2 = LEVEL3;
/**
* UNIT is the greatest number of bits that can be held in one level1 entry.
* That is, bits per word by words per level3 block by blocks per level2 area.
*/
protected static final int UNIT = LENGTH2 * LENGTH3 * LENGTH4;
/**
* MASK2 is the mask to extract the LEVEL2 address from a word index
* (after shifting by SHIFT3 and SHIFT2).
*/
protected static final int MASK2 = LENGTH2 - 1;
/**
* SHIFT1 is the shift to bring the level1 address (from the word index) to
* the right end (i.e., after shifting by SHIFT3).
*/
protected static final int SHIFT1 = LEVEL2 + LEVEL3;
/**
* Holds reference to the cache of statistics values computed by the
* UpdateStrategy
* @see SparseBitSet.Cache
* @see SparseBitSet.UpdateStrategy
*/
protected transient Cache cache;
//=============================================================================
// Stack structures used for recycling blocks
//=============================================================================
/**
* A spare level 3 block is kept for use when scanning. When a target block
* is needed, and there is not already one in the bit set, the spare is
* provided. If non-zero values are placed into this block, it is moved to the
* resulting set, and a new spare is acquired. Note: a new spare needs to
* be allocated when the set is cloned (so that the spare is not shared
* between two sets).
*/
protected transient long[] spare;
/** An empty level 3 block is kept for use when scanning. When a source block
* is needed, and there is not already one in the corresponding bit set, the
* ZERO_BLOCK is used (as a read-only block). It is a source of zero values
* so that code does not have to test for a null level3 block. This is a
* static block shared everywhere.
*/
static final long[] ZERO_BLOCK = new long[LENGTH3];
/* Programming notes:
i, j, and k are used to hold values that are actual bit indices (i.e.,
the index (label) of the bit within the user's view of the bit set).
u, v, and w, are used to hold values that refer to the indices of the
words in the set array that are used to hold the bits (with 64 bits per
word). These variable names, followed by 1, 2, or 3, refer to the component
"level" parts of the complete word index.
word (where used) is a potential entry to or from a block, containing 64
bits of the bit set. The prefixes a, b, result, etc., refer to the bit
sets from which these are coming or going. Without a prefix, or with the
prefix "a," the set in question is "this" set (see next paragraph).
Operations are conceived to be in the form a.op(b), thus in the discussion
(not in the public Javadoc documentation) the two sets are referred to a
"a" and "b", where the set referred to by "this" is usually set a.
Hence, reference to set a is usually implicit, but set b will usually be
explicit. Variables beginning with these letters hold values relevant to
the corresponding set, and, in particular, these letters followed by
1, 2, and 3 are used to refer to the corresponding (current) level1,
level3 area, and level3 block, arrays.
The resizing of the table takes place as necessary. In this regard, it is
worth noting that the table is grown, but never shrunk (except in a new
object formed by cloning).
Similarly, care it taken to ensure that any supplied reference to a bit
set (other than this) has an opportunity to fail for being null before
any other set (including this) has its state changed. For the most
part, this is allowed to happen "naturally," but the Strategies incorporate
an explicit check when necessary.
There is a amount of (almost) repetitive scanning code in many of the
"singe bit" methods. The intent is that these methods for SparseBitSet be
as small and as fast as possible.
For the scanning of complete sets, or for ranges within complete sets,
all of the scanning logic is built into one (somewhat enormous) method,
setScanner(). This contains all the considerations for matching up
corresponding level 3 blocks (if they exist), and then uses a Strategy
object to do the processing on those level3 blocks. This keeps all
the scanning and optimization logic in one place, and the Strategies are
reasonably simple (see the definition of AbstractStrategy for a discussion
of the tasks that must be defined therein).
The test for index i (the first index in all cases) being in range is
rather perverse, but the idea was to keep the actual number of comparisons
to a minimum, hence the check is for "(i + 1) < 1". This is almost but not
quite equivalent to "i < 0", although it is for all values of i except
i=Integer.MAX_VALUE. In this latter case, (i + 1) "overflows" to
-(Integer.MAX_VALUE + 1), and thus appears to be less than 1, and thus the
check picks up the other disallowed case. Let us hope the compiler never
gets smart enough to try to do the apparent optimisation! */
/**
* Constructor for a new (sparse) bit set. All bits initially are effectively
* false. This is a internal constructor that collects all the
* needed actions to initialise the bit set.
*
* The capacity is taken to be a suggestion for a size of the bit set,
* in bits. An appropiate table size (a power of two) is then determined and
* used. The size will be grown as needed to accomodate any bits addressed
* during the use of the bit set.
*
* @param capacity a size in terms of bits
* @param compactionCount the compactionCount to be inherited (for
* internal generation)
* @exception NegativeArraySizeException if the specified initial size
* is negative
* @since 1.6
*/
protected SparseBitSet(int capacity, int compactionCount)
throws NegativeArraySizeException
{
/* Array size is computed based on this being a capacity given in bits. */
if (capacity < 0) // capacity can't be negative -- could only come from
throw new NegativeArraySizeException( // an erroneous user given
"(requested capacity=" + capacity + ") < 0"); // nbits value
resize(capacity - 1); // Resize takes last usable index
this.compactionCount = compactionCount;
/* Ensure there is a spare level 3 block for the use of the set scanner.*/
constructorHelper();
statisticsUpdate();
}
/**
* Constructs an empty bit set with the default initial size.
* Initially all bits are effectively false.
*
* @since 1.6
*/
public SparseBitSet()
{
/* By requesting 1 bit, will actually get UNIT number of bits. */
this(1, compactionCountDefault);
}
/**
* Creates a bit set whose initial size is large enough to efficiently
* represent bits with indices in the range 0 through
* at least nbits-1. Initially all bits are effectively
* false.
*
* No guarantees are given for how large or small the actual object will be.
* The setting of bits above the given range is permitted (and will perhaps
* eventually cause resizing).
*
* @param nbits the initial provisional length of the SparseBitSet
* @throws java.lang.NegativeArraySizeException if the specified initial
* length is negative
* @see #SparseBitSet()
* @since 1.6
*/
public SparseBitSet(int nbits) throws NegativeArraySizeException
{
this(nbits, compactionCountDefault);
}
/**
* Performs a logical AND of the addressed target bit with the argument
* value. This bit set is modified so that the addressed bit has the value
* true if and only if it both initially had the value
* true and the argument value is also true.
*
* @param i a bit index
* @param value a boolean value to AND with that bit
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void and(int i, boolean value) throws IndexOutOfBoundsException
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
if (!value)
clear(i);
}
/**
* Performs a logical AND of this target bit set with the argument bit
* set within the given range of bits. Within the range, this bit set is
* modified so that each bit in it has the value true if and only
* if it both initially had the value true and the corresponding
* bit in the bit set argument also had the value true. Outside
* the range, this set is not changed.
*
* @param i index of the first bit to be included in the operation
* @param j index after the last bit to included in the operation
* @param b a SparseBitSet
* @exception IndexOutOfBoundsException if i is negative or
* equal to Integer.MAX_VALUE, or j is negative,
* or i is larger than j
* @since 1.6
*/
public void and(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
{
setScanner(i, j, b, andStrategy);
}
/**
* Performs a logical AND of this target bit set with the argument bit
* set. This bit set is modified so that each bit in it has the value
* true if and only if it both initially had the value
* true and the corresponding bit in the bit set argument also
* had the value true.
*
* @param b a SparseBitSet
* @since 1.6
*/
public void and(SparseBitSet b)
{
nullify(Math.min(bits.length, b.bits.length)); // Optimisation
setScanner(0, Math.min(bitsLength, b.bitsLength), b, andStrategy);
}
/**
* Performs a logical AND of the two given SparseBitSets.
* The returned SparseBitSet is created so that each bit in it
* has the value true if and only if both the given sets
* initially had the corresponding bits true, otherwise
* false.
*
* @param a a SparseBitSet
* @param b another SparseBitSet
* @return a new SparseBitSet representing the AND of the two sets
* @since 1.6
*/
public static SparseBitSet and(SparseBitSet a, SparseBitSet b)
{
final SparseBitSet result = a.clone();
result.and(b);
return result;
}
/**
* Performs a logical AndNOT of the addressed target bit with the
* argument value. This bit set is modified so that the addressed bit has the
* value true if and only if it both initially had the value
* true and the argument value is false.
*
* @param i a bit index
* @param value a boolean value to AndNOT with that bit
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void andNot(int i, boolean value)
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
if (value)
clear(i);
}
/**
* Performs a logical AndNOT of this target bit set with the argument
* bit set within the given range of bits. Within the range, this bit set is
* modified so that each bit in it has the value true if and only
* if it both initially had the value true and the corresponding
* bit in the bit set argument has the value false. Outside
* the range, this set is not changed.
*
* @param i index of the first bit to be included in the operation
* @param j index after the last bit to included in the operation
* @param b the SparseBitSet with which to mask this SparseBitSet
* @exception IndexOutOfBoundsException if i is negative or
* equal to Integer.MAX_VALUE, or j is negative,
* or i is larger than j
* @since 1.6
*/
public void andNot(int i, int j, SparseBitSet b)
throws IndexOutOfBoundsException
{
setScanner(i, j, b, andNotStrategy);
}
/**
* Performs a logical AndNOT of this target bit set with the argument
* bit set. This bit set is modified so that each bit in it has the value
* true if and only if it both initially had the value
* true and the corresponding bit in the bit set argument has
* the value false.
*
* @param b the SparseBitSet with which to mask this SparseBitSet
* @since 1.6
*/
public void andNot(SparseBitSet b)
{
setScanner(0, Math.min(bitsLength, b.bitsLength), b, andNotStrategy);
}
/**
* Creates a bit set from thie first SparseBitSet whose
* corresponding bits are cleared by the set bits of the second
* SparseBitSet. The resulting bit set is created so that a bit
* in it has the value true if and only if the corresponding bit
* in the SparseBitSet of the first is set, and that same
* corresponding bit is not set in the SparseBitSet of the second
* argument.
*
* @param a a SparseBitSet
* @param b another SparseBitSet
* @return a new SparseBitSet representing the AndNOT of the
* two sets
* @since 1.6
*/
public static SparseBitSet andNot(SparseBitSet a, SparseBitSet b)
{
final SparseBitSet result = a.clone();
result.andNot(b);
return result;
}
/**
* Returns the number of bits set to true in this
* SparseBitSet.
*
* @return the number of bits set to true in this SparseBitSet
* @since 1.6
*/
public int cardinality()
{
statisticsUpdate(); // Update size, cardinality and length values
return cache.cardinality;
}
/**
* Sets the bit at the specified index to false.
*
* @param i a bit index.
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE.
* @since 1.6
*/
public void clear(int i)
{
/* In the interests of speed, no check is made here on whether the
level3 block goes to all zero. This may be found and corrected
in some later operation. */
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
if (i >= bitsLength)
return;
final int w = i >> SHIFT3;
long[][] a2;
if ((a2 = bits[w >> SHIFT1]) == null)
return;
long[] a3;
if ((a3 = a2[(w >> SHIFT2) & MASK2]) == null)
return;
a3[w & MASK3] &= ~(1L << i); // Clear the indicated bit
cache.hash = 0; // Invalidate size, etc.,
}
/**
* Sets the bits from the specified i (inclusive) to the
* specified j (exclusive) to false.
*
* @param i index of the first bit to be cleared
* @param j index after the last bit to be cleared
* @exception IndexOutOfBoundsException if i is negative or
* equal to Integer.MAX_VALUE, or j is negative,
* or i is larger than j
* @since 1.6
*/
public void clear(int i, int j) throws IndexOutOfBoundsException
{
setScanner(i, j, null, clearStrategy);
}
/**
* Sets all of the bits in this SparseBitSet to
* false.
*
* @since 1.6
*/
public void clear()
{
/* This simply resets to null all the entries in the set. */
nullify(0);
}
/**
* Cloning this SparseBitSet produces a new
* SparseBitSet that is equal() to it. The clone of the
* bit set is another bit set that has exactly the same bits set to
* true as this bit set.
*
* Note: the actual space allocated to the clone tries to minimise the actual
* amount of storage allocated to hold the bits, while still trying to
* keep access to the bits being a rapid as possible. Since the space
* allocated to a SparseBitSet is not normally decreased,
* replacing a bit set by its clone may be a way of both managing memory
* consumption and improving the rapidity of access.
*
* @return a clone of this SparseBitSet
* @since 1.6
*/
@Override
public SparseBitSet clone()
{
try
{
final SparseBitSet result = (SparseBitSet) super.clone();
/* Clear out the shallow copy of the set array (which contains just
copies of the references from this set), and then replace these
by a deep copy (created by a "copy" from the set being cloned . */
result.bits = null;
result.resize(1);
/* Ensure the clone is not sharing a copy of a spare block with
the cloned set, nor the cache set, nor any of the visitors (which
are linked to their parent object) (Not all visitors actually use
this link to their containing object, but they are reset here just
in case of future changes). */
result.constructorHelper();
result.equalsStrategy = null;
result.setScanner(0, bitsLength, this, copyStrategy);
return result;
}
catch (CloneNotSupportedException ex)
{
/* This code has not been unit tested. Inspection offers hope
that is will work, but it likely never to be used. */
throw new InternalError(ex.getMessage());
}
}
/**
* Compares this object against the specified object. The result is
* true if and only if the argument is not null
* and is a SparseBitSet object that has exactly the same bits
* set to true as this bit set. That is, for every nonnegative
* i indexing a bit in the set,
*
((SparseBitSet)obj).get(i) == this.get(i)
* must be true.
*
* @param obj the Object with which to compare
* @return true if the objects are equivalent;
* false otherwise.
* @since 1.6
*/
@Override
public boolean equals(Object obj)
{
/* Sanity and quick checks. */
if (!(obj instanceof SparseBitSet))
return false;
final SparseBitSet b = (SparseBitSet) obj;
if (this == b)
return true; // Identity
/* Do the real work. */
if (equalsStrategy == null)
equalsStrategy = new EqualsStrategy();
setScanner(0, Math.max(bitsLength, b.bitsLength), b, equalsStrategy);
return equalsStrategy.result;
}
/**
* Sets the bit at the specified index to the complement of its current value.
*
* @param i the index of the bit to flip
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void flip(int i)
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
final int w = i >> SHIFT3;
final int w1 = w >> SHIFT1;
final int w2 = (w >> SHIFT2) & MASK2;
if (i >= bitsLength)
resize(i);
long[][] a2;
if ((a2 = bits[w1]) == null)
a2 = bits[w1] = new long[LENGTH2][];
long[] a3;
if ((a3 = a2[w2]) == null)
a3 = a2[w2] = new long[LENGTH3];
a3[w & MASK3] ^= 1L << i; //Flip the designated bit
cache.hash = 0; // Invalidate size, etc., values
}
/**
* Sets each bit from the specified i (inclusive) to the
* specified j (exclusive) to the complement of its current
* value.
*
* @param i index of the first bit to flip
* @param j index after the last bit to flip
* @exception IndexOutOfBoundsException if i is negative or is
* equal to Integer.MAX_VALUE, or j is negative, or
* i is larger than j
* @since 1.6
*/
public void flip(int i, int j) throws IndexOutOfBoundsException
{
setScanner(i, j, null, flipStrategy);
}
/**
* Returns the value of the bit with the specified index. The value is
* true if the bit with the index i is currently set
* in this SparseBitSet; otherwise, the result is
* false.
*
* @param i the bit index
* @return the boolean value of the bit with the specified index.
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public boolean get(int i)
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
final int w = i >> SHIFT3;
long[][] a2;
long[] a3;
return i < bitsLength && (a2 = bits[w >> SHIFT1]) != null
&& (a3 = a2[(w >> SHIFT2) & MASK2]) != null
&& ((a3[w & MASK3] & (1L << i)) != 0);
}
/**
* Returns a new SparseBitSet composed of bits from this
* SparseBitSet from i (inclusive) to j
* (exclusive).
*
* @param i index of the first bit to include
* @param j index after the last bit to include
* @return a new SparseBitSet from a range of this SparseBitSet
* @exception IndexOutOfBoundsException if i is negative or is
* equal to Integer.MAX_VALUE, or j is negative, or
* i is larger than j
* @since 1.6
*/
public SparseBitSet get(int i, int j) throws IndexOutOfBoundsException
{
final SparseBitSet result = new SparseBitSet(j, compactionCount);
result.setScanner(i, j, this, copyStrategy);
return result;
}
/**
* Returns a hash code value for this bit set. The hash code depends only on
* which bits have been set within this SparseBitSet. The
* algorithm used to compute it may be described as follows.
*
* Suppose the bits in the SparseBitSet were to be stored in an
* array of long integers called, say, bits, in such
* a manner that bit i is set in the SparseBitSet
* (for nonnegative values of i) if and only if the expression
*
* ((i>>6) < bits.length) && ((bits[i>>6] & (1L << (bit & 0x3F))) != 0)
*
* is true. Then the following definition of the hashCode method
* would be a correct implementation of the actual algorithm:
*
* public int hashCode()
* {
* long hash = 1234L;
* for( int i = bits.length; --i >= 0; )
* hash ^= bits[i] * (i + 1);
* return (int)((h >> 32) ^ h);
* }
* Note that the hash code values change if the set of bits is altered.
*
* @return a hash code value for this bit set
* @since 1.6
* @see Object#equals(Object)
* @see java.util.Hashtable
*/
@Override
public int hashCode()
{
statisticsUpdate();
return cache.hash;
}
/**
* Returns true if the specified SparseBitSet has any bits
* within the given range i (inclusive) to j
* (exclusive) set to true that are also set to true
* in the same range of this SparseBitSet.
*
* @param i index of the first bit to include
* @param j index after the last bit to include
* @param b the SparseBitSet with which to intersect
* @return the boolean indicating whether this SparseBitSet intersects the
* specified SparseBitSet
* @exception IndexOutOfBoundsException if i is negative or
* equal to Integer.MAX_VALUE, or j is negative,
* or i is larger than j
* @since 1.6
*/
public boolean intersects(int i, int j, SparseBitSet b)
throws IndexOutOfBoundsException
{
setScanner(i, j, b, intersectsStrategy);
return intersectsStrategy.result;
}
/**
* Returns true if the specified SparseBitSet has any bits set to
* true that are also set to true in this
* SparseBitSet.
*
* @param b a SparseBitSet with which to intersect
* @return boolean indicating whether this SparseBitSet intersects the
* specified SparseBitSet
* @since 1.6
*/
public boolean intersects(SparseBitSet b)
{
setScanner(0, Math.max(bitsLength, b.bitsLength), b, intersectsStrategy);
return intersectsStrategy.result;
}
/**
* Returns true if this SparseBitSet contains no bits that are
* set to true.
*
* @return the boolean indicating whether this SparseBitSet is empty
* @since 1.6
*/
public boolean isEmpty()
{
statisticsUpdate();
return cache.cardinality == 0;
}
/**
* Returns the "logical length" of this SparseBitSet: the index
* of the highest set bit in the SparseBitSet plus one. Returns
* zero if the SparseBitSet contains no set bits.
*
* @return the logical length of this SparseBitSet
* @since 1.6
*/
public int length()
{
statisticsUpdate();
return cache.length;
}
/**
* Returns the index of the first bit that is set to false that
* occurs on or after the specified starting index.
*
* @param i the index to start checking from (inclusive)
* @return the index of the next clear bit, or -1 if there is no such bit
* @exception IndexOutOfBoundsException if the specified index is negative
* @since 1.6
*/
public int nextClearBit(int i)
{
/* The index of this method is permitted to be Integer.MAX_VALUE, as this
is needed to make this method work together with the method
nextSetBit()--as might happen if a search for the next clear bit is
started after finding a set bit labelled Integer.MAX_VALUE-1. This
case is not optimised, the code will eventually return -1 (since
the Integer.MAX_VALUEth bit does "exist," and is 0. */
if (i < 0)
throw new IndexOutOfBoundsException("i=" + i);
/* This is the word from which the search begins. */
int w = i >> SHIFT3;
int w3 = w & MASK3;
int w2 = (w >> SHIFT2) & MASK2;
int w1 = w >> SHIFT1;
long nword = ~0L << i;
final int aLength = bits.length;
long[][] a2;
long[] a3;
/* Is the next clear bit in the same word at the nominated beginning bit
(including the nominated beginning bit itself). The first check is
whether the starting bit is within the structure at all. */
if (w1 < aLength && (a2 = bits[w1]) != null
&& (a3 = a2[w2]) != null
&& ((nword = ~a3[w3] & (~0L << i))) == 0L)
{
/* So now start a search though the rest of the entries for
a null area or block, or a clear bit (a set bit in the
complemented value). */
++w;
w3 = w & MASK3;
w2 = (w >> SHIFT2) & MASK2;
w1 = w >> SHIFT1;
nword = ~0L;
loop: for (; w1 != aLength; ++w1)
{
if ((a2 = bits[w1]) == null)
break;
for (; w2 != LENGTH2; ++w2)
{
if ((a3 = a2[w2]) == null)
break loop;
for (; w3 != LENGTH3; ++w3)
if ((nword = ~a3[w3]) != 0)
break loop;
w3 = 0;
}
w2 = w3 = 0;
}
}
final int result = (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3)
+ Long.numberOfTrailingZeros(nword);
return (result == Integer.MAX_VALUE ? -1 : result);
}
/**
* Returns the index of the first bit that is set to true that
* occurs on or after the specified starting index. If no such it exists then
* -1 is returned.
*
* To iterate over the true bits in a SparseBitSet
* sbs, use the following loop:
*
*
* for( int i = sbbits.nextSetBit(0); i >= 0; i = sbbits.nextSetBit(i+1) )
* {
* // operate on index i here
* }
*
* @param i the index to start checking from (inclusive)
* @return the index of the next set bit
* @exception IndexOutOfBoundsException if the specified index is negative
* @since 1.6
*/
public int nextSetBit(int i)
{
/* The index value (i) of this method is permitted to be Integer.MAX_VALUE,
as this is needed to make the loop defined above work: just in case the
bit labelled Integer.MAX_VALUE-1 is set. This case is not optimised:
but eventually -1 will be returned, as this will be included with
any search that goes off the end of the level1 array. */
if (i < 0)
throw new IndexOutOfBoundsException("i=" + i);
/* This is the word from which the search begins. */
int w = i >> SHIFT3;
int w3 = w & MASK3;
int w2 = (w >> SHIFT2) & MASK2;
int w1 = w >> SHIFT1;
long word = 0L;
final int aLength = bits.length;
long[][] a2;
long[] a3;
/* Is the next set bit in the same word at the nominated beginning bit
(including the nominated beginning bit itself). The first check is
whether the starting bit is within the structure at all. */
if (w1 < aLength && ((a2 = bits[w1]) == null
|| (a3 = a2[w2]) == null
|| ((word = a3[w3] & (~0L << i)) == 0L)))
{
/* So now start a search though the rest of the entries for a bit. */
++w;
w3 = w & MASK3;
w2 = (w >> SHIFT2) & MASK2;
w1 = w >> SHIFT1;
major: for (; w1 != aLength; ++w1)
{
if ((a2 = bits[w1]) != null)
for (; w2 != LENGTH2; ++w2)
{
if ((a3 = a2[w2]) != null)
for (; w3 != LENGTH3; ++w3)
if ((word = a3[w3]) != 0)
break major;
w3 = 0;
}
w2 = w3 = 0;
}
}
return (w1 >= aLength ? -1
: (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3)
+ Long.numberOfTrailingZeros(word));
}
/**
* Returns the index of the nearest bit that is set to {@code false}
* that occurs on or before the specified starting index.
* If no such bit exists, or if {@code -1} is given as the
* starting index, then {@code -1} is returned.
*
* @param i the index to start checking from (inclusive)
* @return the index of the previous clear bit, or {@code -1} if there
* is no such bit
* @throws IndexOutOfBoundsException if the specified index is less
* than {@code -1}
* @since 1.2
* @see java.util.BitSet#previousClearBit
*/
public int previousClearBit(int i)
{
if (i < 0)
{
if (i == -1)
return -1;
throw new IndexOutOfBoundsException("i=" + i);
}
final long[][][] bits = this.bits;
final int aLength = bits.length;
int w = i >> SHIFT3;
int w3 = w & MASK3;
int w2 = (w >> SHIFT2) & MASK2;
int w1 = w >> SHIFT1;
if (w1 > aLength - 1)
return i;
w1 = Math.min(w1, aLength - 1);
final int w4 = i % LENGTH4;
long word;
long[][] a2;
long[] a3;
final int f3 = w3;
final int f2 = w2;
final int f1 = w1;
for (; w1 >= 0; --w1)
{
if ((a2 = bits[w1]) == null)
return (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3)
+ (f1 == w1 ? w4 : LENGTH4 - 1);
for (; w2 >= 0; --w2)
{
if ((a3 = a2[w2]) == null)
return (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3)
+ (f2 == w2 ? w4 : LENGTH4 - 1);
for (; w3 >= 0; --w3)
{
if ((word = a3[w3]) == 0)
return (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3)
+ (f3 == w3 ? w4 : LENGTH4 - 1);
for (int bitIdx = w4; bitIdx >= 0; --bitIdx)
{
if ((word & (1L << bitIdx)) == 0)
return (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3) + bitIdx;
}
}
w3 = LENGTH3 - 1;
}
w2 = LENGTH2 - 1;
w3 = LENGTH3 - 1;
}
return -1;
}
/**
* Returns the index of the nearest bit that is set to {@code true}
* that occurs on or before the specified starting index.
* If no such bit exists, or if {@code -1} is given as the
* starting index, then {@code -1} is returned.
*
* @param i the index to start checking from (inclusive)
* @return the index of the previous set bit, or {@code -1} if there
* is no such bit
* @throws IndexOutOfBoundsException if the specified index is less
* than {@code -1}
* @since 1.2
* @see java.util.BitSet#previousSetBit
*/
public int previousSetBit(int i)
{
if (i < 0)
{
if (i == -1)
return -1;
throw new IndexOutOfBoundsException("i=" + i);
}
final long[][][] bits = this.bits;
final int aLength = bits.length;
/* This is the word from which the search begins. */
final int w = i >> SHIFT3;
int w1 = w >> SHIFT1;
int w2, w3, w4;
/* But if its off the end of the array, start from the very end. */
if (w1 > aLength - 1)
{
w1 = aLength - 1;
w2 = LENGTH2 - 1;
w3 = LENGTH3 - 1;
w4 = LENGTH4 - 1;
}
else
{
w2 = (w >> SHIFT2) & MASK2;
w3 = w & MASK3;
w4 = i % LENGTH4;
}
boolean initialWord = true;
long word;
long[][] a2;
long[] a3;
for (; w1 >= 0; --w1, initialWord = false)
{
if ((a2 = bits[w1]) != null)
for (; w2 >= 0; --w2, initialWord = false)
{
if ((a3 = a2[w2]) != null)
for (; w3 >= 0; --w3, initialWord = false)
{
if ((word = a3[w3]) != 0)
for (int bitIdx = (initialWord ? w4 : LENGTH4 - 1); bitIdx >= 0; --bitIdx)
{
if ((word & (1L << bitIdx)) != 0)
return (((w1 << SHIFT1) + (w2 << SHIFT2) + w3) << SHIFT3) + bitIdx;
}
}
w3 = LENGTH3 - 1;
}
w2 = LENGTH2 - 1;
w3 = LENGTH3 - 1;
}
return -1;
}
/**
* Performs a logical OR of the addressed target bit with the
* argument value. This bit set is modified so that the addressed bit has the
* value true if and only if it both initially had the value
* true or the argument value is true.
*
* @param i a bit index
* @param value a boolean value to OR with that bit
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void or(int i, boolean value)
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
if (value)
set(i);
}
/**
* Performs a logical OR of the addressed target bit with the
* argument value within the given range. This bit set is modified so that
* within the range a bit in it has the value true if and only if
* it either already had the value true or the corresponding bit
* in the bit set argument has the value true. Outside the range
* this set is not changed.
*
* @param i index of the first bit to be included in the operation
* @param j index after the last bit to included in the operation
* @param b the SparseBitSet with which to perform the OR
* operation with this SparseBitSet
* @exception IndexOutOfBoundsException if i is negative or
* equal to Integer.MAX_VALUE, or j is negative,
* or i is larger than j
* @since 1.6
*/
public void or(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
{
setScanner(i, j, b, orStrategy);
}
/**
* Performs a logical OR of this bit set with the bit set argument.
* This bit set is modified so that a bit in it has the value true
* if and only if it either already had the value true or the
* corresponding bit in the bit set argument has the value true.
*
* @param b the SparseBitSet with which to perform the OR
* operation with this SparseBitSet
* @since 1.6
*/
public void or(SparseBitSet b)
{
setScanner(0, b.bitsLength, b, orStrategy);
}
/**
* Performs a logical OR of the two given SparseBitSets.
* The returned SparseBitSet is created so that a bit in it has
* the value true if and only if it either had the value
* true in the set given by the first arguemetn or had the value
* true in the second argument, otherwise false.
*
* @param a a SparseBitSet
* @param b another SparseBitSet
* @return new SparseBitSet representing the OR of the two sets
* @since 1.6
*/
public static SparseBitSet or(SparseBitSet a, SparseBitSet b)
{
final SparseBitSet result = a.clone();
result.or(b);
return result;
}
/**
* Sets the bit at the specified index.
*
* @param i a bit index
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void set(int i)
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
final int w = i >> SHIFT3;
final int w1 = w >> SHIFT1;
final int w2 = (w >> SHIFT2) & MASK2;
if (i >= bitsLength)
resize(i);
long[][] a2;
if ((a2 = bits[w1]) == null)
a2 = bits[w1] = new long[LENGTH2][];
long[] a3;
if ((a3 = a2[w2]) == null)
a3 = a2[w2] = new long[LENGTH3];
a3[w & MASK3] |= 1L << i;
cache.hash = 0; //Invalidate size, etc., scan
}
/**
* Sets the bit at the specified index to the specified value.
*
* @param i a bit index
* @param value a boolean value to set
* @exception IndexOutOfBoundsException if the specified index is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void set(int i, boolean value)
{
if (value)
set(i);
else
clear(i);
}
/**
* Sets the bits from the specified i (inclusive) to the specified
* j (exclusive) to true.
*
* @param i index of the first bit to be set
* @param j index after the last bit to be se
* @exception IndexOutOfBoundsException if i is negative or is
* equal to Integer.MAX_INT, or j is negative, or
* i is larger than j.
* @since 1.6
*/
public void set(int i, int j) throws IndexOutOfBoundsException
{
setScanner(i, j, null, setStrategy);
}
/**
* Sets the bits from the specified i (inclusive) to the specified
* j (exclusive) to the specified value.
*
* @param i index of the first bit to be set
* @param j index after the last bit to be set
* @param value to which to set the selected bits
* @exception IndexOutOfBoundsException if i is negative or is
* equal to Integer.MAX_VALUE, or j is negative, or
* i is larger than j
* @since 1.6
*/
public void set(int i, int j, boolean value)
{
if (value)
set(i, j);
else
clear(i, j);
}
/**
* Returns the number of bits of space nominally in use by this
* SparseBitSet to represent bit values. The count of bits in
* the set is the (label of the last set bit) + 1 - (the label of the first
* set bit).
*
* @return the number of bits (true and false) nominally in this bit set
* at this moment
* @since 1.6
*/
public int size()
{
statisticsUpdate();
return cache.size;
}
/**
* Convenience method for statistics if the individual results are not needed.
*
* @return a String detailing the statistics of the bit set
* @see #statistics(String[])
* @since 1.6
*/
public String statistics()
{
return statistics(null);
}
/**
* Determine, and create a String with the bit set statistics. The statistics
* include: Size, Length, Cardinality, Total words (i.e., the total
* number of 64-bit "words"), Set array length (i.e., the number of
* references that can be held by the top level array, Level2 areas in use,
* Level3 blocks in use,, Level2 pool size, Level3 pool size, and the
* Compaction count.
*
* This method is intended for diagnostic use (as it is relatively expensive
* in time), but can be useful in understanding an application's use of a
* SparseBitSet.
*
* @param values an array for the individual results (if not null)
* @return a String detailing the statistics of the bit set
* @since 1.6
*/
public String statistics(String[] values)
{
statisticsUpdate(); // Ensure statistics are up-to-date
String[] v = new String[Statistics.values().length];
/* Assign the statistics values to the appropriate entry. The order
of the assignments does not matter--the ordinal serves to get the
values into the matching order with the labels from the enumeration. */
v[Statistics.Size.ordinal()] = Integer.toString(size());
v[Statistics.Length.ordinal()] = Integer.toString(length());
v[Statistics.Cardinality.ordinal()] = Integer.toString(cardinality());
v[Statistics.Total_words.ordinal()] = Integer.toString(cache.count);
v[Statistics.Set_array_length.ordinal()] = Integer.toString(bits.length);
v[Statistics.Set_array_max_length.ordinal()] =
Integer.toString(MAX_LENGTH1);
v[Statistics.Level2_areas.ordinal()] = Integer.toString(cache.a2Count);
v[Statistics.Level2_area_length.ordinal()] = Integer.toString(LENGTH2);
v[Statistics.Level3_blocks.ordinal()] = Integer.toString(cache.a3Count);
v[Statistics.Level3_block_length.ordinal()] = Integer.toString(LENGTH3);
v[Statistics.Compaction_count_value.ordinal()] =
Integer.toString(compactionCount);
/* Determine the longest label, so that the equal signs may be lined-up. */
int longestLabel = 0;
for (Statistics s : Statistics.values())
longestLabel =
Math.max(longestLabel, s.name().length());
/* Build a String that has for each statistic, the name of the statistic,
padding, and equals sign, and the value. The "Load_factor_value",
"Average_length_value", and "Average_chain_length" are printed as
floating point values. */
final StringBuilder result = new StringBuilder();
for (Statistics s : Statistics.values())
{
result.append(s.name()); // The name of the statistic
for (int i = 0; i != longestLabel - s.name().length(); ++i)
result.append(' '); // Fill out the field
result.append(" = "); // Show an equals sign
result.append(v[s.ordinal()]); // and a value
result.append('\n');
}
/* Remove the underscores. */
for (int i = 0; i != result.length(); ++i)
if (result.charAt(i) == '_')
result.setCharAt(i, ' ');
if (values != null)
{
final int len = Math.min(values.length, v.length);
System.arraycopy(v, 0, values, 0, len);
}
return result.toString();
}
/**
* Returns a string representation of this bit set. For every index for which
* this SparseBitSet contains a bit in the set state, the decimal
* representation of that index is included in the result. Such indices are
* listed in order from lowest to highest. If there is a subsequence of set
* bits longer than the value given by toStringCompaction, the subsequence
* is represented by the value for the first and the last values, with ".."
* between them. The individual bits, or the representation of sub-sequences
* are separated by ", " (a comma and a space) and surrounded by braces,
* resulting in a compact string showing (a variant of) the usual mathematical
* notation for a set of integers.
*
* Example (with the default value of 2 for subsequences):
*
* SparseBitSet drPepper = new SparseBitSet();
*
* Now drPepper.toString() returns "{}".
*
*
* drPepper.set(2);
*
* Now drPepper.toString() returns "{2}".
*
*
* drPepper.set(3, 4);
* drPepper.set(10);
*
* Now drPepper.toString() returns "{2..4, 10}".
*
* This method is intended for diagnostic use (as it is relatively expensive
* in time), but can be useful in interpreting problems in an application's use
* of a SparseBitSet.
*
* @return a String representation of this SparseBitSet
* @see #toStringCompaction(int length)
* @since 1.6
*/
@Override
public String toString()
{
final StringBuilder p = new StringBuilder(200);
p.append('{');
int i = nextSetBit(0);
/* Loop so long as there is another bit to append to the String. */
while (i >= 0)
{
/* Append that next bit */
p.append(i);
/* Find the position of the next bit to show. */
int j = nextSetBit(i + 1);
if (compactionCount > 0)
{
/* Give up if there is no next bit to show. */
if (j < 0)
break;
/* Find the next clear bit is after the current bit, i.e., i */
int last = nextClearBit(i);
/* Compute the position of the next clear bit after the current
subsequence of set bits. */
last = (last < 0 ? Integer.MAX_VALUE : last);
/* If the subsequence is more than the specified bits long, then
collapse the subsequence into one entry in the String. */
if (i + compactionCount < last)
{
p.append("..").append(last - 1);
/* Having accounted for a subsequence of bits that are all set,
recompute the label of the next bit to show. */
j = nextSetBit(last);
}
}
/* If there is another set bit, put a comma and a space after the
last entry in the String. */
if (j >= 0)
p.append(", ");
/* Transfer to i the index of the next set bit. */
i = j;
}
/* Terminate the representational String, and return it. */
p.append('}');
return p.toString();
}
/** Sequences of set bits longer than this value are shown by
* {@link #toString()} as a "sub-sequence," in the form a..b.
* Setting this value to zero causes each set bit to be listed individually.
* The default default value is 2 (which means sequences of three or more
* bits set are shown as a subsequence, and all other set bits are listed
* individually).
*
* Note: this value will be passed to SparseBitSets that
* may be created within or as a result of the operations on this bit set,
* or, for static methods, from the value belonging to the first parameter.
*
* @param count the maximum count of a run of bits that are shown as
* individual entries in a toString() conversion.
* If 0, all bits are shown individually.
* @since 1.6
* @see #toString()
*/
public void toStringCompaction(int count)
{
compactionCount = count;
}
/**
* If change is true, the current value of the
* toStringCompaction() value is made the default value for all
* SparseBitSets created from this point onward in this JVM.
*
* @param change if true, change the default value
* @since 1.6
*/
public void toStringCompaction(boolean change)
{
/* This is an assignment to a static value: the integer value assignment
is atomic, so there will not be a partial store. If multiple
invocations are made from multiple threads, there is a race
condition that cannot be resolved by synchronization. */
if (change)
compactionCountDefault = compactionCount;
}
/**
* Performs a logical XOR of the addressed target bit with the
* argument value. This bit set is modified so that the addressed bit has the
* value true if and only one of the following statements holds:
*
* - The addressed bit initially had the value
true, and the
* value of the argument is false.
* - The bit initially had the value
false, and the
* value of the argument is true.
*
*
* @param i a bit index
* @param value a boolean value to XOR with that bit
* @exception java.lang.IndexOutOfBoundsException if the specified index
* is negative
* or equal to Integer.MAX_VALUE
* @since 1.6
*/
public void xor(int i, boolean value)
{
if ((i + 1) < 1)
throw new IndexOutOfBoundsException("i=" + i);
if (value)
flip(i);
}
/**
* Performs a logical XOR of this bit set with the bit set argument
* within the given range. This resulting bit set is computed so that a bit
* within the range in it has the value true if and only if one
* of the following statements holds:
*
* - The bit initially had the value
true, and the
* corresponding bit in the argument set has the value false.
* - The bit initially had the value
false, and the
* corresponding bit in the argument set has the value true.
*
* Outside the range this set is not changed.
*
* @param i index of the first bit to be included in the operation
* @param j index after the last bit to included in the operation
* @param b the SparseBitSet with which to perform the XOR
* operation with this SparseBitSet
* @exception IndexOutOfBoundsException if i is negative or
* equal to Integer.MAX_VALUE, or j is negative,
* or i is larger than j
* @since 1.6
*/
public void xor(int i, int j, SparseBitSet b) throws IndexOutOfBoundsException
{
setScanner(i, j, b, xorStrategy);
}
/**
* Performs a logical XOR of this bit set with the bit set argument.
* This resulting bit set is computed so that a bit in it has the value
* true if and only if one of the following statements holds:
*
* - The bit initially had the value
true, and the
* corresponding bit in the argument set has the value false.
* - The bit initially had the value
false, and the
* corresponding bit in the argument set has the value true.
*
*
* @param b the SparseBitSet with which to perform the XOR
* operation with thisSparseBitSet
* @since 1.6
*/
public void xor(SparseBitSet b)
{
setScanner(0, b.bitsLength, b, xorStrategy);
}
/**
* Performs a logical XOR of the two given SparseBitSets.
* The resulting bit set is created so that a bit in it has the value
* true if and only if one of the following statements holds:
*
* - A bit in the first argument has the value
true, and the
* corresponding bit in the second argument has the value
* false.
* - A bit in the first argument has the value
false, and the
* corresponding bit in the second argument has the value
* true.
*
* @param a a SparseBitSet
* @param b another SparseBitSet
* @return a new SparseBitSet representing the XOR of the two sets
* @since 1.6
*/
public static SparseBitSet xor(SparseBitSet a, SparseBitSet b)
{
final SparseBitSet result = a.clone();
result.xor(b);
return result;
}
//==============================================================================
// Internal methods
//==============================================================================
/**
* Throw the exception to indicate a range error. The String
* constructed reports all the possible errors in one message.
*
* @param i lower bound for a operation
* @param j upper bound for a operation
* @exception IndexOutOfBoundsException indicating the range is not valid
* @since 1.6
*/
protected static void throwIndexOutOfBoundsException(int i, int j)
throws IndexOutOfBoundsException
{
String s = "";
if (i < 0)
s += "(i=" + i + ") < 0";
if (i == Integer.MAX_VALUE)
s += "(i=" + i + ")";
if (j < 0)
s += (s.isEmpty() ? "" : ", ") + "(j=" + j + ") < 0";
if (i > j)
s += (s.isEmpty() ? "" : ", ") + "(i=" + i + ") > (j=" + j + ")";
throw new IndexOutOfBoundsException(s);
}
/**
* Intializes all the additional objects required for correct operation.
*
* @since 1.6
*/
protected final void constructorHelper()
{
spare = new long[LENGTH3];
cache = new Cache();
updateStrategy = new UpdateStrategy();
}
/**
* Clear out a part of the set array with nulls, from the given start to the
* end of the array. If the given parameter is beyond the end of the bits
* array, nothing is changed.
*
* @param start word index at which to start (inclusive)
* @since 1.6
*/
protected final void nullify(int start)
{
final int aLength = bits.length;
if (start < aLength)
{
for (int w = start; w != aLength; ++w)
bits[w] = null;
cache.hash = 0; // Invalidate size, etc., values
}
}
/**
* Resize the bit array. Moves the entries in the the bits array of this
* SparseBitSet into an array whose size (which may be larger or smaller) is
* the given bit size (i.e., includes the bit whose index is one less
* that the given value). If the new array is smaller, the excess entries in
* the set array are discarded. If the new array is bigger, it is filled with
* nulls.
*
* @param index the desired address to be included in the set
* @since 1.6
*/
protected final void resize(int index)
{
/* Find an array size that is a power of two that is as least as large
enough to contain the index requested. */
final int w1 = (index >> SHIFT3) >> SHIFT1;
int newSize = Integer.highestOneBit(w1);
if (newSize == 0)
newSize = 1;
if (w1 >= newSize)
newSize <<= 1;
if (newSize > MAX_LENGTH1)
newSize = MAX_LENGTH1;
final int aLength1 = (bits != null ? bits.length : 0);
if (newSize != aLength1 || bits == null)
{ // only if the size needs to be changed
final long[][][] temp = new long[newSize][][]; // Get the new array
if (aLength1 != 0)
{
/* If it exists, copy old array to the new array. */
System.arraycopy(bits, 0, temp, 0, Math.min(aLength1, newSize));
nullify(0); // Don't leave unused pointers around. */
}
bits = temp; // Set new array as the set array
bitsLength = // Index of last possible bit, plus one.
(newSize == MAX_LENGTH1 ? Integer.MAX_VALUE : newSize * UNIT);
}
}
/**
* Scans over the bit set (and a second bit set if part of the operation) are
* all performed by this method. The properties and the operation executed
* are defined by a given strategy, which must be derived from the
* AbstractStrategy. The strategy defines how to operate on a
* single word, and on whole words that may or may not constitute a full
* block of words.
*
* @param i the bit (inclusive) at which to start the scan
* @param j the bit (exclusive) at which to stop the scan
* @param b a SparseBitSet, if needed, the second SparseBitSet in the
* operation
* @param op the AbstractStrategy class defining the operation to be
* executed
* @exception IndexOutOfBoundsException
* @since 1.6
* @see AbstractStrategy
*/
protected final void setScanner(int i, int j, SparseBitSet b,
AbstractStrategy op) throws IndexOutOfBoundsException
{
/* This method has been assessed as having a McCabe cyclomatic
complexity of 47 (i.e., impossibly high). However, given that this
method incorporates all the set scanning logic for all methods
(with the exception of nextSetBit and nextClearBit, which themselves
have high cyclomatic complexities of 13), and is attempting to minimise
execution time (hence deals with processing shortcuts), it cannot be
expected to be simple. In fact, the work of lining up level3 blocks
proceeds step-wise, and each sub-section piece is reasonably
straight-forward. Nevertheless, the number of paths is high, and
caution is advised in attempting to correct anything. */
/* Do whatever the strategy needs to get started, and do whatever initial
checking is needed--fail here if needed before much else is done. */
if (op.start(b))
cache.hash = 0;
if (j < i || (i + 1) < 1)
throwIndexOutOfBoundsException(i, j);
if (i == j)
return;
/* Get the values of all the short-cut options. */
final int properties = op.properties();
final boolean f_op_f_eq_f = (properties & AbstractStrategy.F_OP_F_EQ_F) != 0;
final boolean f_op_x_eq_f = (properties & AbstractStrategy.F_OP_X_EQ_F) != 0;
final boolean x_op_f_eq_f = (properties & AbstractStrategy.X_OP_F_EQ_F) != 0;
final boolean x_op_f_eq_x = (properties & AbstractStrategy.X_OP_F_EQ_X) != 0;
/* Index of the current word, and mask for the first word,
to be processed in the bit set. */
int u = i >> SHIFT3;
final long um = ~0L << i;
/* Index of the final word, and mask for the final word,
to be processed in the bit set. */
final int v = (j - 1) >> SHIFT3;
final long vm = ~0L >>> -j;
/* Set up the two bit arrays (if the second exists), and their
corresponding lengths (if any). */
long[][][] a1 = bits; // Level1, i.e., the bit arrays
int aLength1 = bits.length;
final long[][][] b1 = (b != null ? b.bits : null);
final int bLength1 = (b1 != null ? b.bits.length : 0);
/* Calculate the initial values of the parts of the words addresses,
as well as the location of the final block to be processed. */
int u1 = u >> SHIFT1;
int u2 = (u >> SHIFT2) & MASK2;
int u3 = u & MASK3;
final int v1 = v >> SHIFT1;
final int v2 = (v >> SHIFT2) & MASK2;
final int v3 = v & MASK3;
final int lastA3Block = (v1 << LEVEL2) + v2;
/* Initialize the local copies of the counts of blocks and areas; and
whether there is a partial first block. */
int a2CountLocal = 0;
int a3CountLocal = 0;
boolean notFirstBlock = u == 0 && um == ~0L;
/* The first level2 is cannot be judged empty if not being scanned from
the beginning. */
boolean a2IsEmpty = u2 == 0; // Presumption
while (i < j)
{
/* Determine if there is a level2 area in both the a and the b set,
and if so, set the references to these areas. */
long[][] a2 = null;
boolean haveA2 = u1 < aLength1 && (a2 = a1[u1]) != null;
long[][] b2 = null;
final boolean haveB2 = u1 < bLength1
&& b1 != null && (b2 = b1[u1]) != null;
/* Handling of level 2 empty areas: determined by the
properties of the strategy. It is necessary to actually visit
the first and last blocks of a scan, since not all of the block
might participate in the operation, hence making decision based
on just the references to the blocks could be wrong. */
if ((!haveA2 && !haveB2 && f_op_f_eq_f
|| !haveA2 && f_op_x_eq_f || !haveB2 && x_op_f_eq_f)
&& notFirstBlock && u1 != v1)
{//nested if!
if (u1 < aLength1)
a1[u1] = null;
}
else
{
final int limit2 = (u1 == v1 ? v2 + 1 : LENGTH2);
while (u2 != limit2)
{
/* Similar logic applied here as for the level2 blocks.
The initial and final block must be examined. In other
cases, it may be possible to make a decision based on
the value of the references, as indicated by the
properties of the strategy. */
long[] a3 = null;
final boolean haveA3 = haveA2 && (a3 = a2[u2]) != null;
long[] b3 = null;
final boolean haveB3 = haveB2 && (b3 = b2[u2]) != null;
final int a3Block = (u1 << LEVEL2) + u2;
final boolean notLastBlock = lastA3Block != a3Block;
/* Handling of level 3 empty areas: determined by the
properties of the strategy. */
if ((!haveA3 && !haveB3 && f_op_f_eq_f
|| !haveA3 && f_op_x_eq_f || !haveB3 && x_op_f_eq_f)
&& notFirstBlock && notLastBlock)
{
/* Do not need level3 block, so remove it, and move on. */
if (haveA2)
a2[u2] = null;
}
else
{
/* So what is needed is the level3 block. */
final int base3 = a3Block << SHIFT2;
final int limit3 = (notLastBlock ? LENGTH3 : v3);
if (!haveA3)
a3 = spare;
if (!haveB3)
b3 = ZERO_BLOCK;
boolean isZero;
if (notFirstBlock && notLastBlock)
if (x_op_f_eq_x && !haveB3)
isZero = op.isZeroBlock(a3);
// b block is null, just check a block
else
isZero = op.block(base3, 0, LENGTH3, a3, b3);
// Do the operation on the whole block
else
{ /* Partial block to process. */
if (notFirstBlock)
{
/* By implication, this is the last block */
isZero = op.block(base3, 0, limit3, a3, b3);
// Do the whole words
isZero &= op.word(base3, limit3, a3, b3, vm);
// And then the final word
}
else
{ // u, v are correct if first block
if (u == v) // Scan starts and ends in one word
isZero = op.word(base3, u3, a3, b3, um & vm);
else
{ // Scan starts in this a3 block
isZero = op.word(base3, u3, a3, b3, um);
// First word
isZero &=
op.block(base3, u3 + 1, limit3, a3, b3);
// Remainder of full words in block
if (limit3 != LENGTH3)
isZero &= op.word(base3, limit3, a3, b3, vm);
// If there is a partial word left
}
notFirstBlock = true; // Only one first block
}
if (isZero)
isZero = op.isZeroBlock(a3);
// If not known to have a non-zero
// value, be sure whether all zero.
}
if (isZero) // The resulting a3 block has no values
{// nested if!
/* If there is an level 2 area make the entry for this
level3 block be a null (i.e., remove any a3 block ). */
if (haveA2)
a2[u2] = null;
}
else
{
/* If the a3 block used was the spare block, put it
into current level2 area; get a new spare block. */
if (a3 == spare)
{
if (i >= bitsLength) //Check that the set is large
{ // enough to take the new block
resize(i); // Make it large enough
a1 = bits; // Update reference and length
aLength1 = a1.length;
}
if (a2 == null) // Ensure a level 2 area
{
a1[u1] = a2 = new long[LENGTH2][];
haveA2 = true; // Ensure know level2 not empty
}
a2[u2] = a3; // Insert the level3 block
spare = new long[LENGTH3]; // Replace the spare
}
++a3CountLocal; // Count the level 3 block
}
a2IsEmpty &= !(haveA2 && a2[u2] != null);
} // Keep track of level 2 usage
++u2;
u3 = 0;
} /* end while ( u2 != limit2 ) */
/* If the loop finishes without completing the level 2, it may
be left with a reference but still be all null--this is OK. */
if (u2 == LENGTH2 && a2IsEmpty && u1 < aLength1)
a1[u1] = null;
else
++a2CountLocal; // Count level 2 areas
}
/* Advance the value of u based on what happened. */
i = (u = (++u1 << SHIFT1)) << SHIFT3;
u2 = 0; // u3 = 0
// Compute next word and bit index
if (i < 0)
i = Integer.MAX_VALUE; // Don't go over the end
} /* end while( i < j ) */
/* Do whatever the strategy needs in order to finish. */
op.finish(a2CountLocal, a3CountLocal);
}
/**
* The entirety of the bit set is examined, and the various statistics of
* the bit set (size, length, cardinality, hashCode, etc.) are computed. Level
* arrays that are empty (i.e., all zero at level 3, all null at level 2) are
* replaced by null references, ensuring a normalized representation.
*
* @since 1.6
*/
protected final void statisticsUpdate()
{
if (cache.hash != 0)
return;
setScanner(0, bitsLength, null, updateStrategy);
}
//==============================================================================
// Serialization/Deserialization methods
//==============================================================================
/**
* Save the state of the SparseBitSet instance to a stream
* (i.e., serialize it).
*
* @param s the ObjectOutputStream to which to write the serialized object
* @exception java.io.IOException if an io error occurs
* @exception java.lang.InternalError if the SparseBitSet representation is
* inconsistent
*
* @serialData The default data is emitted, followed by the current
* compactionCount for the bit set, and then the
* length of the set (the position of the last bit),
* followed by the cache.count value (an int,
* the number of int->long pairs needed to describe
* the set), followed by the index (int) and word
* (long) for each int->long pair.
* The mappings need not be emitted in any particular order. This
* is followed by the hashCode for the set that can be used
* as an integrity check when the bit set is read back.
*
* @since 1.6
*/
private void writeObject(ObjectOutputStream s) throws IOException, InternalError
{
statisticsUpdate(); // Update structure and stats if needed.
/* Write any hidden stuff. */
s.defaultWriteObject();
s.writeInt(compactionCount); // Needed to preserve value
s.writeInt(cache.length); // Needed to know where last bit is
/* This is the number of index/value pairs to be written. */
int count = cache.count; // Minimum number of words to be written
s.writeInt(count);
final long[][][] a1 = bits;
final int aLength1 = a1.length;
long[][] a2;
long[] a3;
long word;
for (int w1 = 0; w1 != aLength1; ++w1)
if ((a2 = a1[w1]) != null)
for (int w2 = 0; w2 != LENGTH2; ++w2)
if ((a3 = a2[w2]) != null)
{
final int base = (w1 << SHIFT1) + (w2 << SHIFT2);
for (int w3 = 0; w3 != LENGTH3; ++w3)
if ((word = a3[w3]) != 0)
{
s.writeInt(base + w3);
s.writeLong(word);
--count;
}
}
if (count != 0)
throw new InternalError("count of entries not consistent");
/* As a consistency check, write the hash code of the set. */
s.writeInt(cache.hash);
}
/**
* serialVersionUID
*/
private static final long serialVersionUID = -6663013367427929992L;
/**
* Reconstitute the SparseBitSet instance from a stream
* (i.e., deserialize it).
*
* @param s the ObjectInputStream to use
* @exception IOException if there is an io error
* @exception ClassNotFoundException if the stream contains an unidentified
* class
* @since 1.6
*/
private void readObject(ObjectInputStream s) throws IOException,
ClassNotFoundException
{
/* Read in any hidden stuff that is part of the class overhead. */
s.defaultReadObject();
compactionCount = s.readInt();
final int aLength = s.readInt();
resize(aLength); // Make sure there is enough space
/* Read in number of mappings. */
final int count = s.readInt();
/* Read the keys and values, them into the set array, areas, and blocks. */
long[][] a2;
long[] a3;
for (int n = 0; n != count; ++n)
{
final int w = s.readInt();
final int w3 = w & MASK3;
final int w2 = (w >> SHIFT2) & MASK2;
final int w1 = w >> SHIFT1;
final long word = s.readLong();
if ((a2 = bits[w1]) == null)
a2 = bits[w1] = new long[LENGTH2][];
if ((a3 = a2[w2]) == null)
a3 = a2[w2] = new long[LENGTH3];
a3[w3] = word;
}
/* Ensure all the pieces are set up for set scanning. */
constructorHelper();
statisticsUpdate();
if (count != cache.count)
throw new InternalError("count of entries not consistent");
final int hash = s.readInt(); // Get the hashcode that was stored
if (hash != cache.hash) // An error of some kind if not the same
throw new IOException("deserialized hashCode mis-match");
}
//=============================================================================
// Statistics enumeration
//=============================================================================
/**
* These enumeration values are used as labels for the values in the String
* created by the statistics() method. The values of the corresponding
* statistics are ints, except for the loadFactor and
* Average_chain_length values, which are floats.
*
* An array of Strings may be obtained containing a
* representation of each of these values. An element of such an array, say,
* values, may be accessed, for example, by:
*
* values[SparseBitSet.statistics.Buckets_available.ordinal()]
*
* @see #statistics(String[])
*/
public enum Statistics
{
/**
* The size of the bit set, as give by the size() method.
*/
Size, // 0
/**
* The length of the bit set, as give by the length() method.
*/
Length, // 1
/**
* The cardinality of the bit set, as give by the cardinality() method.
*/
Cardinality, // 2
/**
* The total number of non-zero 64-bits "words" being used to hold the
* representation of the bit set.
*/
Total_words, // 3
/**
* The length of the bit set array.
*/
Set_array_length, // 4
/**
* The maximum permitted length of the bit set array.
*/
Set_array_max_length, // 5
/**
* The number of level2 areas.
*/
Level2_areas, // 6
/**
* The length of the level2 areas.
*/
Level2_area_length, // 7
/**
* The total number of level3 blocks in use.
*/
Level3_blocks, // 8
/**
* The length of the level3 blocks.
*/
Level3_block_length, // 9
/**
* Is the value that determines how the toString() conversion is
* performed.
* @see #toStringCompaction(int)
*/
Compaction_count_value // 10
}
//=============================================================================
// A set of cached statistics values, recomputed when necessary
//=============================================================================
/**
* This class holds the values related to various statistics kept about the
* bit set. These values are not kept continuously up-to-date. Whenever the
* values become invalid, the field hash is set to zero, indicating
* that an update is required.
*
* @see #statisticsUpdate()
*/
protected class Cache
{
/**
* hash is updated by the statisticsUpdate() method.
* If the hash value is zero, it is assumed that all
* the cached values are stale, and must be updated.
*/
protected transient int hash;
/**
* size is updated by the statisticsUpdate() method.
* If the hash value is zero, it is assumed the all the cached
* values are stale, and must be updated.
*/
protected transient int size;
/**
* cardinality is updated by the statisticsUpdate() method.
* If the hash value is zero, it is assumed the all the cached
* values are stale, and must be updated.
*/
protected transient int cardinality;
/**
* length is updated by the statisticsUpdate() method.
* If the hash value is zero, it is assumed the all the cached
* values are stale, and must be updated.
*/
protected transient int length;
/**
* count is updated by the statisticsUpdate() method.
* If the hash value is zero, it is assumed the all the cached
* values are stale, and must be updated.
*/
protected transient int count;
/**
* a2Count is updated by the statisticsUpdate()
* method, and will only be correct immediately after a full update. The
* hash value is must be zero for all values to be updated.
*/
protected transient int a2Count;
/**
* a3Count is updated by the statisticsUpdate() method,
* and will only be correct immediately after a full update. The
* hash value is must be zero for all values to be updated.
*/
protected transient int a3Count;
}
//=============================================================================
// Abstract Strategy super-class for Strategies describing logical operations
//=============================================================================
/**
* This strategy class is used by the setScanner to carry out the a variety
* of operations on this set, and usually a second set. The
* setScanner() method of the main SparseBitSet class
* essentially finds matching level3 blocks, and then calls the strategy to
* do the appropriate operation on each of the elements of the block.
*
* The symbolic constants control optimisation paths in the
* setScanner() method of the main SparseBitSet class.
*
* @see SparseBitSet#setScanner(int i, int j,
* SparseBitSet b, AbstractStrategy op)
*/
protected abstract static class AbstractStrategy
{
/** If the operation requires that when matching level2 areas or level3
* blocks are null, that no action is required, then this property is
* required. Corresponds to the top-left entry in the logic diagram for the
* operation being 0. For all the defined actual logic operations ('and',
* 'andNot', 'or', and 'xor', this will be true, because for all these,
* "false" op "false" = "false".
*/
static final int F_OP_F_EQ_F = 0x1;
/** If when level2 areas or level3 areas from the this set are null will
* require that area or block to remain null, irrespective of the value of
* the matching structure from the other set, then this property is required.
* Corresponds to the first row in the logic diagram being all zeros. For
* example, this is true for 'and' as well as 'andNot', and for 'clear', since
* false" & "x" = "false", and "false" &! "x" = "false".
*/
static final int F_OP_X_EQ_F = 0x2;
/** If when level2 areas or level3 areas from the other set are null will
* require the matching area or block in this set to be set to null,
* irrespective of the current values in the matching structure from the
* this, then this property is required. Corresponds to the first column
* in the logic diagram being all zero. For example, this is true for
* 'and', since "x" & "false" = "false", as well as for 'clear'.
*/
static final int X_OP_F_EQ_F = 0x4;
/** If when a level3 area from the other set is null will require the
* matching area or block in this set to be left as it is, then this property
* is required. Corresponds to the first column of the logic diagram being
* equal to the left hand operand column. For example, this is true for 'or',
* 'xor', and 'andNot', since for all of these "x" op "false" = "x".
*/
static final int X_OP_F_EQ_X = 0x8;
/**
* Properties of this strategy.
*
* @return the int containing the bits representing the properties of
* this strategy
* @since 1.6
*/
protected abstract int properties();
/**
* Instances of this class are to be serially reusable. To start a
* particular use, an instance is (re-)started by calling this method. It is
* passed the reference to the other bit set (usually to allow a check on
* whether it is null or not, so as to simplify the implementation of the
* block() method.
*
* @param b the "other" set, for whatever checking is needed.
* @since 1.6
* @return true -> if the cache should be set to zero
*/
protected abstract boolean start(SparseBitSet b);
/**
* Deal with a scan that include a partial word within a level3 block. All
* that is required is that the result be stored (if needed) into the
* given a set block at the correct position, and that the operation only
* affect those bits selected by 1 bits in the mask.
*
* @param base the base index of the block (to be used if needed)
* @param u3 the index of the word within block
* @param a3 the level3 block from the a set.
* @param b3 the (nominal) level3 block from the b set (not null).
* @param mask for the (partial) word
* @return true if the resulting word is zero
* @since 1.6
*/
protected abstract boolean word(int base, int u3, long[] a3, long[] b3, long mask);
/**
* Deals with a part of a block that consists of whole words, starting with
* the given first index, and ending with the word before the last index.
* For the words processed, the return value should indicate whether all those
* resulting words were zero, or not.
*
* @param base the base index of the block (to be used if needed)
* @param u3 the index of the first word within block to process
* @param v3 the index of the last word, which may be within block
* @param a3 the level3 block from the a set.
* @param b3 the (nominal) level3 block from the b set (not null).
* @return true if the words scanned within the level3 block were all zero
* @since 1.6
*/
protected abstract boolean block(int base, int u3, int v3, long[] a3, long[] b3);
/**
* This is called to finish the processing started by the strategy (if there
* needs to be anything done at all).
*
* @param a2Count possible count of level2 areas in use
* @param a3Count possible count of level3 blocks in use
* @since 1.6
*/
protected void finish(int a2Count, int a3Count)
{
}
/**
* Check whether a level3 block is all zero.
*
* @param a3 the block from the a set
* @return true if the values of the level3 block are all zero
*
* @since 1.6
*/
protected final boolean isZeroBlock(long[] a3)
{
for (long word : a3)
if (word != 0L)
return false;
return true;
}
}
//=============================================================================
// Strategies based on the Strategy super-class describing logical operations
//=============================================================================
/**
* And of two sets. Where the a set is zero, it remains zero (i.e.,
* without entries or with zero words). Similarly, where the b set is
* zero, the a becomes zero (i.e., without entries).
*
* If level1 of the a set is longer than level1 of the bit set
* b, then the unmatched virtual "entries" of the b set (beyond
* the actual length of b) corresponding to these are all false, hence
* the result of the "and" operation will be to make all these entries in this
* set to become false--hence just remove them, and then scan only those
* entries that could match entries in the bit setb. This clearing of
* the remainder of the a set is accomplished by selecting both
* F_OP_X_EQ_F and X_OP_F_EQ_F.
*
*
* and| 0 1
* 0| 0 0
* 1| 0 1
*/
protected static class AndStrategy extends AbstractStrategy
{
@Override
// AndStrategy
protected int properties()
{
return F_OP_F_EQ_F + F_OP_X_EQ_F + X_OP_F_EQ_F;
}
@Override
// AndStrategy
protected boolean start(SparseBitSet b)
{
if (b == null)
throw new NullPointerException();
return true;
}
@Override
// AndStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] &= b3[u3] | ~mask) == 0L;
}
@Override
// AndStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
isZero &= ((a3[w3] &= b3[w3]) == 0L);
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* AndNot of two sets. Where the a set is zero, it remains zero
* (i.e., without entries or with zero words). On the other hand, where the
* b set is zero, the a remains unchanged.
*
* If level1 of the a set is longer than level1 of the bit set
* b, then the unmatched virtual "entries" of the b set (beyond
* the actual length of b) corresponding to these are all false, hence
* the result of the "and" operation will be to make all these entries in this
* set to become false--hence just remove them, and then scan only those
* entries that could match entries in the bit setb. This clearing of
* the remainder of the a set is accomplished by selecting both
* F_OP_X_EQ_F and X_OP_F_EQ_F.
*
*
* andNot| 0 1
* 0| 0 0
* 1| 1 0
*/
protected static class AndNotStrategy extends AbstractStrategy
{
@Override
// AndNotStrategy
protected int properties()
{
return F_OP_F_EQ_F + F_OP_X_EQ_F + X_OP_F_EQ_X;
}
@Override
// AndNotStrategy
protected boolean start(SparseBitSet b)
{
if (b == null)
throw new NullPointerException();
return true;
}
@Override
// AndNotStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] &= ~(b3[u3] & mask)) == 0L;
}
@Override
// AndNotStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
isZero &= (a3[w3] &= ~b3[w3]) == 0L;
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* Clear clears bits in the a set.
*
*
* clear| 0 1
* 0| 0 0
* 1| 0 0
*/
protected static class ClearStrategy extends AbstractStrategy
{
@Override
// ClearStrategy
protected int properties()
{
return F_OP_F_EQ_F + F_OP_X_EQ_F;
}
@Override
// ClearStrategy
protected boolean start(SparseBitSet b)
{
return true;
}
@Override
// ClearStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] &= ~mask) == 0L;
}
@Override
// ClearStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
if (u3 != 0 || v3 != LENGTH3) // Optimisation
for (int w3 = u3; w3 != v3; ++w3)
a3[w3] = 0L;
return true;
}
}
//-----------------------------------------------------------------------------
/**
* Copies the needed parts of the b set to the a set.
*
*
* get| 0 1
* 0| 0 1
* 1| 0 1
*/
protected static class CopyStrategy extends AbstractStrategy
{
@Override
// CopyStrategy
protected int properties()
{
return F_OP_F_EQ_F + X_OP_F_EQ_F;
}
@Override
// CopyStrategy
protected boolean start(SparseBitSet b)
{
return true;
}
@Override
// CopyStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] = b3[u3] & mask) == 0L;
}
@Override
// CopyStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true;
for (int w3 = u3; w3 != v3; ++w3)
isZero &= (a3[w3] = b3[w3]) == 0L;
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* Equals compares bits in the a set with those in the b set.
* None of the values in either set are changed, although the a set
* may have all zero level 3 blocks replaced by null references (and
* similarly at level 2).
*
*
* equals| 0 1
* 0| 0 -
* 1| - -
*/
protected static class EqualsStrategy extends AbstractStrategy
{
boolean result; // Used to hold result of the comparison
@Override
// EqualsStrategy
protected int properties()
{
return F_OP_F_EQ_F;
}
@Override
// EqualsStrategy
protected boolean start(SparseBitSet b)
{
if (b == null)
throw new NullPointerException();
result = true;
return false;
/* Equals does not change the content of the set, hence hash need
not be reset. */
}
@Override
// EqualsStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
final long word = a3[u3];
result &= (word & mask) == (b3[u3] & mask);
return word == 0L;
}
@Override
// EqualsStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
{
final long word = a3[w3];
result &= word == b3[w3];
isZero &= word == 0L;
}
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* Flip inverts the bits of the a set within the given range.
*
*
* flip| 0 1
* 0| 1 1
* 1| 0 0
*/
protected static class FlipStrategy extends AbstractStrategy
{
@Override
// FlipStrategy
protected int properties()
{
return 0;
}
@Override
// FlipStrategy
protected boolean start(SparseBitSet b)
{
return true;
}
@Override
// FlipStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] ^= mask) == 0L;
}
@Override
// FlipStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
isZero &= (a3[w3] ^= ~0L) == 0L;
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* Intersect has a true result if any word in the a set has a bit
* in common with the b set. During the scan of the a set
* blocks (and areas) that are all zero may be replaced with empty blocks
* and areas (null references), but the value of the set is not changed
* (which is why X_OP_F_EQ_F is not selected, since this would cause
* parts of the a set to be zero-ed out).
*
*
* intersect| 0 1
* 0| 0 0
* 1| 1 1
*/
protected static class IntersectsStrategy extends AbstractStrategy
{
/**
* The boolean result of the intersects scan Strategy is kept here.
*/
protected boolean result;
@Override
// IntersectsStrategy
protected int properties()
{
return F_OP_F_EQ_F + F_OP_X_EQ_F;
}
@Override
// IntersectsStrategy
protected boolean start(SparseBitSet b)
{
if (b == null)
throw new NullPointerException();
result = false;
return false;
/* Intersect does not change the content of the set, hence hash
need not be reset. */
}
@Override
// IntersectsStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
final long word = a3[u3];
result |= (word & b3[u3] & mask) != 0L;
return word == 0L;
}
@Override
// IntersectsStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
{
final long word = a3[w3];
result |= (word & b3[w3]) != 0L;
isZero &= word == 0L;
}
return isZero;
}
}
/**
* Or of two sets. Where the a set is one, it remains one. Similarly,
* where the b set is one, the a becomes one. If both sets have
* zeros in corresponding places, a zero results. Whole blocks or areas that
* are or become zero are replaced by null arrays.
*
* If level1 of the a set is longer than level1 of the bit set
* b, then the unmatched entries of the a set (beyond
* the actual length of b) corresponding to these remain unchanged. *
*
* or| 0 1
* 0| 0 1
* 1| 1 1
*/
protected static class OrStrategy extends AbstractStrategy
{
@Override
// OrStrategy
protected int properties()
{
return F_OP_F_EQ_F + X_OP_F_EQ_X;
}
@Override
// OrStrategy
protected boolean start(SparseBitSet b)
{
if (b == null)
throw new NullPointerException();
return true;
}
@Override
// OrStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] |= b3[u3] & mask) == 0L;
}
@Override
// OrStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
isZero &= (a3[w3] |= b3[w3]) == 0L;
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* Set creates entries everywhere within the range. Hence no empty level2
* areas or level3 blocks are ignored, and no empty (all zero) blocks are
* returned.
*
*
* set| 0 1
* 0| 1 1
* 1| 1 1
*/
protected static class SetStrategy extends AbstractStrategy
{
@Override
// SetStrategy
protected int properties()
{
return 0;
}
@Override
// SetStrategy
protected boolean start(SparseBitSet b)
{
return true;
}
@Override
// SetStrategy
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
a3[u3] |= mask;
return false;
}
@Override
// SetStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
for (int w3 = u3; w3 != v3; ++w3)
a3[w3] = ~0L;
return false; // set always sets bits
}
}
//-----------------------------------------------------------------------------
/**
* Update the seven statistics that are computed for each set. These are
* updated by calling statisticsUpdate, which uses this strategy.
*
*
* update| 0 1
* 0| 0 0
* 1| 1 1
*
* @see SparseBitSet#statisticsUpdate()
*/
protected class UpdateStrategy extends AbstractStrategy
{
/**
* Working space for find the size and length of the bit set. Holds the
* index of the first non-empty word in the set.
*/
protected transient int wMin;
/**
* Working space for find the size and length of the bit set. Holds copy of
* the first non-empty word in the set.
*/
protected transient long wordMin;
/**
* Working space for find the size and length of the bit set. Holds the
* index of the last non-empty word in the set.
*/
protected transient int wMax;
/**
* Working space for find the size and length of the bit set. Holds a copy
* of the last non-empty word in the set.
*/
protected transient long wordMax;
/**
* Working space for find the hash value of the bit set. Holds the
* current state of the computation of the hash value. This value is
* ultimately transferred to the Cache object.
*
* @see SparseBitSet.Cache
*/
protected transient long hash;
/**
* Working space for keeping count of the number of non-zero words in the
* bit set. Holds the current state of the computation of the count. This
* value is ultimately transferred to the Cache object.
*
* @see SparseBitSet.Cache
*/
protected transient int count;
/**
* Working space for counting the number of non-zero bits in the bit set.
* Holds the current state of the computation of the cardinality.This
* value is ultimately transferred to the Cache object.
*
* @see SparseBitSet.Cache
*/
protected transient int cardinality;
@Override
// UpdateStrategy
protected int properties()
{
return F_OP_F_EQ_F + F_OP_X_EQ_F;
}
/**
* This method initializes the computations by suitably resetting cache
* fields or working fields.
*
* @param b the other SparseBitSet, for checking if needed.
*
* @since 1.6
*/
@Override
protected boolean start(SparseBitSet b)
{
hash = 1234L; // Magic number
wMin = -1; // index of first non-zero word
wordMin = 0L; // word at that index
wMax = 0; // index of last non-zero word
wordMax = 0L; // word at that index
count = 0; // count of non-zero words in whole set
cardinality = 0; // count of non-zero bits in the whole set
return false;
}
@Override
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
final long word = a3[u3];
final long word1 = word & mask;
if (word1 != 0L)
compute(base + u3, word1);
return word == 0L;
}
@Override
// UpdateStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = 0; w3 != v3; ++w3)
{
final long word = a3[w3];
if (word != 0)
{
isZero = false;
compute(base + w3, word);
}
}
return isZero;
}
@Override
// UpdateStrategy
protected void finish(int a2Count, int a3Count)
{
cache.a2Count = a2Count;
cache.a3Count = a3Count;
cache.count = count;
cache.cardinality = cardinality;
cache.length = (wMax + 1) * LENGTH4 - Long.numberOfLeadingZeros(wordMax);
cache.size = cache.length - wMin * LENGTH4
- Long.numberOfTrailingZeros(wordMin);
cache.hash = (int) ((hash >> Integer.SIZE) ^ hash);
}
/**
* This method does the accumulation of the statistics. It must be called
* in sequential order of the words in the set for which the statistics
* are being accumulated, and only for non-null values of the second
* parameter.
*
* Two of the values (a2Count and a3Count) are not updated here,
* but are done in the code near where this method is called.
*
* @param index the word index of the word supplied
* @param word the long non-zero word from the set
* @since 1.6
*/
private void compute(final int index, final long word)
{
/* Count the number of actual words being used. */
++count;
/* Continue to accumulate the hash value of the set. */
hash ^= word * (long) (index + 1);
/* The first non-zero word contains the first actual bit of the
set. The location of this bit is used to compute the set size. */
if (wMin < 0)
{
wMin = index;
wordMin = word;
}
/* The last non-zero word contains the last actual bit of the set.
The location of this bit is used to compute the set length. */
wMax = index;
wordMax = word;
/* Count the actual bits, so as to get the cardinality of the set. */
cardinality += Long.bitCount(word);
}
}
//-----------------------------------------------------------------------------
/**
* The XOR of level3 blocks is computed.
*
*
* xor| 0 1
* 0| 0 1
* 1| 1 0
*/
protected static class XorStrategy extends AbstractStrategy
{
@Override
// XorStrategy
protected int properties()
{
return F_OP_F_EQ_F + X_OP_F_EQ_X;
}
@Override
// XorStrategy
protected boolean start(SparseBitSet b)
{
if (b == null)
throw new NullPointerException();
return true;
}
@Override
protected boolean word(int base, int u3, long[] a3, long[] b3, long mask)
{
return (a3[u3] ^= b3[u3] & mask) == 0;
}
@Override
// XorStrategy
protected boolean block(int base, int u3, int v3, long[] a3, long[] b3)
{
boolean isZero = true; // Presumption
for (int w3 = u3; w3 != v3; ++w3)
isZero &= (a3[w3] ^= b3[w3]) == 0;
return isZero;
}
}
//-----------------------------------------------------------------------------
/**
* Word and block and strategy.
*/
protected static final transient AndStrategy andStrategy = new AndStrategy();
/**
* Word and block andNot strategy.
*/
protected static final transient AndNotStrategy andNotStrategy = new AndNotStrategy();
/**
* Word and block clear strategy.
*/
protected static final transient ClearStrategy clearStrategy = new ClearStrategy();
/**
* Word and block copy strategy.
*/
protected static final transient CopyStrategy copyStrategy = new CopyStrategy();
/**
* Word and block equals strategy.
*/
protected transient EqualsStrategy equalsStrategy;
/**
* Word and block flip strategy.
*/
protected static final transient FlipStrategy flipStrategy = new FlipStrategy();
/**
* Word and block intersects strategy.
*/
protected static transient IntersectsStrategy intersectsStrategy = new IntersectsStrategy();
/**
* Word and block or strategy.
*/
protected static final transient OrStrategy orStrategy = new OrStrategy();
/**
* Word and block set strategy.
*/
protected static final transient SetStrategy setStrategy = new SetStrategy();
/**
* Word and block update strategy.
*/
protected transient UpdateStrategy updateStrategy;
/**
* Word and block xor strategy.
*/
protected static final transient XorStrategy xorStrategy = new XorStrategy();
}