/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.util;
import java.io.IOException;
import java.util.Arrays;
import org.apache.lucene.search.DocIdSet;
import org.apache.lucene.search.DocIdSetIterator;
// TODO: maybe merge with BitVector? Problem is BitVector
// caches its cardinality...
/** BitSet of fixed length (numBits), backed by accessible
* ({@link #getBits}) long[], accessed with an int index,
* implementing Bits and DocIdSet. Unlike {@link
* OpenBitSet} this bit set does not auto-expand, cannot
* handle long index, and does not have fastXX/XX variants
* (just X).
*
* @lucene.internal
**/
public final class FixedBitSet extends DocIdSet implements Bits {
private final long[] bits;
private int numBits;
/** returns the number of 64 bit words it would take to hold numBits */
public static int bits2words(int numBits) {
int numLong = numBits >>> 6;
if ((numBits & 63) != 0) {
numLong++;
}
return numLong;
}
public FixedBitSet(int numBits) {
this.numBits = numBits;
bits = new long[bits2words(numBits)];
}
public FixedBitSet(long[]storedBits,int numBits) {
this.numBits = numBits;
this.bits = storedBits;
}
/** Makes full copy. */
public FixedBitSet(FixedBitSet other) {
bits = new long[other.bits.length];
System.arraycopy(other.bits, 0, bits, 0, bits.length);
numBits = other.numBits;
}
@Override
public DocIdSetIterator iterator() {
return new OpenBitSetIterator(bits, bits.length);
}
@Override
public Bits bits() {
return this;
}
@Override
public int length() {
return numBits;
}
/** This DocIdSet implementation is cacheable. */
@Override
public boolean isCacheable() {
return true;
}
/** Expert. */
public long[] getBits() {
return bits;
}
/** Returns number of set bits. NOTE: this visits every
* long in the backing bits array, and the result is not
* internally cached! */
public int cardinality() {
return (int) BitUtil.pop_array(bits, 0, bits.length);
}
public boolean get(int index) {
assert index >= 0 && index < numBits: "index=" + index;
int i = index >> 6; // div 64
// signed shift will keep a negative index and force an
// array-index-out-of-bounds-exception, removing the need for an explicit check.
int bit = index & 0x3f; // mod 64
long bitmask = 1L << bit;
return (bits[i] & bitmask) != 0;
}
public void set(int index) {
assert index >= 0 && index < numBits;
int wordNum = index >> 6; // div 64
int bit = index & 0x3f; // mod 64
long bitmask = 1L << bit;
bits[wordNum] |= bitmask;
}
public boolean getAndSet(int index) {
assert index >= 0 && index < numBits;
int wordNum = index >> 6; // div 64
int bit = index & 0x3f; // mod 64
long bitmask = 1L << bit;
boolean val = (bits[wordNum] & bitmask) != 0;
bits[wordNum] |= bitmask;
return val;
}
public void clear(int index) {
assert index >= 0 && index < numBits;
int wordNum = index >> 6;
int bit = index & 0x03f;
long bitmask = 1L << bit;
bits[wordNum] &= ~bitmask;
}
public boolean getAndClear(int index) {
assert index >= 0 && index < numBits;
int wordNum = index >> 6; // div 64
int bit = index & 0x3f; // mod 64
long bitmask = 1L << bit;
boolean val = (bits[wordNum] & bitmask) != 0;
bits[wordNum] &= ~bitmask;
return val;
}
/** Returns the index of the first set bit starting at the index specified.
* -1 is returned if there are no more set bits.
*/
public int nextSetBit(int index) {
assert index >= 0 && index < numBits;
int i = index >> 6;
final int subIndex = index & 0x3f; // index within the word
long word = bits[i] >> subIndex; // skip all the bits to the right of index
if (word!=0) {
return (i<<6) + subIndex + BitUtil.ntz(word);
}
while(++i < bits.length) {
word = bits[i];
if (word != 0) {
return (i<<6) + BitUtil.ntz(word);
}
}
return -1;
}
/** Returns the index of the last set bit before or on the index specified.
* -1 is returned if there are no more set bits.
*/
public int prevSetBit(int index) {
assert index >= 0 && index < numBits: "index=" + index + " numBits=" + numBits;
int i = index >> 6;
final int subIndex = index & 0x3f; // index within the word
long word = (bits[i] << (63-subIndex)); // skip all the bits to the left of index
if (word != 0) {
return (i << 6) + subIndex - Long.numberOfLeadingZeros(word); // See LUCENE-3197
}
while (--i >= 0) {
word = bits[i];
if (word !=0 ) {
return (i << 6) + 63 - Long.numberOfLeadingZeros(word);
}
}
return -1;
}
/** Does in-place OR of the bits provided by the
* iterator. */
public void or(DocIdSetIterator iter) throws IOException {
if (iter instanceof OpenBitSetIterator && iter.docID() == -1) {
final OpenBitSetIterator obs = (OpenBitSetIterator) iter;
or(obs.arr, obs.words);
// advance after last doc that would be accepted if standard
// iteration is used (to exhaust it):
obs.advance(numBits);
} else {
int doc;
while ((doc = iter.nextDoc()) < numBits) {
set(doc);
}
}
}
/** this = this OR other */
public void or(FixedBitSet other) {
or(other.bits, other.bits.length);
}
private void or(final long[] otherArr, final int otherLen) {
final long[] thisArr = this.bits;
int pos = Math.min(thisArr.length, otherLen);
while (--pos >= 0) {
thisArr[pos] |= otherArr[pos];
}
}
/** Does in-place AND of the bits provided by the
* iterator. */
public void and(DocIdSetIterator iter) throws IOException {
if (iter instanceof OpenBitSetIterator && iter.docID() == -1) {
final OpenBitSetIterator obs = (OpenBitSetIterator) iter;
and(obs.arr, obs.words);
// advance after last doc that would be accepted if standard
// iteration is used (to exhaust it):
obs.advance(numBits);
} else {
if (numBits == 0) return;
int disiDoc, bitSetDoc = nextSetBit(0);
while (bitSetDoc != -1 && (disiDoc = iter.advance(bitSetDoc)) < numBits) {
clear(bitSetDoc, disiDoc);
disiDoc++;
bitSetDoc = (disiDoc < numBits) ? nextSetBit(disiDoc) : -1;
}
if (bitSetDoc != -1) {
clear(bitSetDoc, numBits);
}
}
}
/** this = this AND other */
public void and(FixedBitSet other) {
and(other.bits, other.bits.length);
}
private void and(final long[] otherArr, final int otherLen) {
final long[] thisArr = this.bits;
int pos = Math.min(thisArr.length, otherLen);
while(--pos >= 0) {
thisArr[pos] &= otherArr[pos];
}
if (thisArr.length > otherLen) {
Arrays.fill(thisArr, otherLen, thisArr.length, 0L);
}
}
/** Does in-place AND NOT of the bits provided by the
* iterator. */
public void andNot(DocIdSetIterator iter) throws IOException {
if (iter instanceof OpenBitSetIterator && iter.docID() == -1) {
final OpenBitSetIterator obs = (OpenBitSetIterator) iter;
andNot(obs.arr, obs.words);
// advance after last doc that would be accepted if standard
// iteration is used (to exhaust it):
obs.advance(numBits);
} else {
int doc;
while ((doc = iter.nextDoc()) < numBits) {
clear(doc);
}
}
}
/** this = this AND NOT other */
public void andNot(FixedBitSet other) {
andNot(other.bits, other.bits.length);
}
private void andNot(final long[] otherArr, final int otherLen) {
final long[] thisArr = this.bits;
int pos = Math.min(thisArr.length, otherLen);
while(--pos >= 0) {
thisArr[pos] &= ~otherArr[pos];
}
}
// NOTE: no .isEmpty() here because that's trappy (ie,
// typically isEmpty is low cost, but this one wouldn't
// be)
/** Flips a range of bits
*
* @param startIndex lower index
* @param endIndex one-past the last bit to flip
*/
public void flip(int startIndex, int endIndex) {
assert startIndex >= 0 && startIndex < numBits;
assert endIndex >= 0 && endIndex <= numBits;
if (endIndex <= startIndex) {
return;
}
int startWord = startIndex >> 6;
int endWord = (endIndex-1) >> 6;
/*** Grrr, java shifting wraps around so -1L>>>64 == -1
* for that reason, make sure not to use endmask if the bits to flip will
* be zero in the last word (redefine endWord to be the last changed...)
long startmask = -1L << (startIndex & 0x3f); // example: 11111...111000
long endmask = -1L >>> (64-(endIndex & 0x3f)); // example: 00111...111111
***/
long startmask = -1L << startIndex;
long endmask = -1L >>> -endIndex; // 64-(endIndex&0x3f) is the same as -endIndex due to wrap
if (startWord == endWord) {
bits[startWord] ^= (startmask & endmask);
return;
}
bits[startWord] ^= startmask;
for (int i=startWord+1; i<endWord; i++) {
bits[i] = ~bits[i];
}
bits[endWord] ^= endmask;
}
/** Sets a range of bits
*
* @param startIndex lower index
* @param endIndex one-past the last bit to set
*/
public void set(int startIndex, int endIndex) {
assert startIndex >= 0 && startIndex < numBits;
assert endIndex >= 0 && endIndex <= numBits;
if (endIndex <= startIndex) {
return;
}
int startWord = startIndex >> 6;
int endWord = (endIndex-1) >> 6;
long startmask = -1L << startIndex;
long endmask = -1L >>> -endIndex; // 64-(endIndex&0x3f) is the same as -endIndex due to wrap
if (startWord == endWord) {
bits[startWord] |= (startmask & endmask);
return;
}
bits[startWord] |= startmask;
Arrays.fill(bits, startWord+1, endWord, -1L);
bits[endWord] |= endmask;
}
/** Clears a range of bits.
*
* @param startIndex lower index
* @param endIndex one-past the last bit to clear
*/
public void clear(int startIndex, int endIndex) {
assert startIndex >= 0 && startIndex < numBits;
assert endIndex >= 0 && endIndex <= numBits;
if (endIndex <= startIndex) {
return;
}
int startWord = startIndex >> 6;
int endWord = (endIndex-1) >> 6;
long startmask = -1L << startIndex;
long endmask = -1L >>> -endIndex; // 64-(endIndex&0x3f) is the same as -endIndex due to wrap
// invert masks since we are clearing
startmask = ~startmask;
endmask = ~endmask;
if (startWord == endWord) {
bits[startWord] &= (startmask | endmask);
return;
}
bits[startWord] &= startmask;
Arrays.fill(bits, startWord+1, endWord, 0L);
bits[endWord] &= endmask;
}
@Override
public FixedBitSet clone() {
return new FixedBitSet(this);
}
/** returns true if both sets have the same bits set */
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof FixedBitSet)) {
return false;
}
FixedBitSet other = (FixedBitSet) o;
if (numBits != other.length()) {
return false;
}
return Arrays.equals(bits, other.bits);
}
@Override
public int hashCode() {
long h = 0;
for (int i = bits.length; --i>=0;) {
h ^= bits[i];
h = (h << 1) | (h >>> 63); // rotate left
}
// fold leftmost bits into right and add a constant to prevent
// empty sets from returning 0, which is too common.
return (int) ((h>>32) ^ h) + 0x98761234;
}
}