/*
// Licensed to Julian Hyde under one or more contributor license
// agreements. See the NOTICE file distributed with this work for
// additional information regarding copyright ownership.
//
// Julian Hyde 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 net.hydromatic.optiq.util;
import org.eigenbase.util.IntList;
import java.util.*;
/**
* Utility functions for {@link BitSet}.
*/
public final class BitSets {
private BitSets() {
throw new AssertionError("no instances!");
}
/**
* Returns true if all bits set in the second parameter are also set in the
* first. In other words, whether x is a super-set of y.
*
* @param set0 Containing bitmap
* @param set1 Bitmap to be checked
*
* @return Whether all bits in set1 are set in set0
*/
public static boolean contains(BitSet set0, BitSet set1) {
for (int i = set1.nextSetBit(0); i >= 0; i = set1.nextSetBit(i + 1)) {
if (!set0.get(i)) {
return false;
}
}
return true;
}
/**
* Returns an iterable over the bits in a bitmap that are set to '1'.
*
* <p>This allows you to iterate over a bit set using a 'foreach' construct.
* For instance:
*
* <blockquote><code>
* BitSet bitSet;<br>
* for (int i : Util.toIter(bitSet)) {<br>
* print(i);<br>
* }</code></blockquote>
*
* @param bitSet Bit set
* @return Iterable
*/
public static Iterable<Integer> toIter(final BitSet bitSet) {
return new Iterable<Integer>() {
public Iterator<Integer> iterator() {
return new Iterator<Integer>() {
int i = bitSet.nextSetBit(0);
public boolean hasNext() {
return i >= 0;
}
public Integer next() {
int prev = i;
i = bitSet.nextSetBit(i + 1);
return prev;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
};
}
/**
* Converts a bitset to a list.
*
* <p>The list is mutable, and future changes to the list do not affect the
* contents of the bit set.
*
* @param bitSet Bit set
* @return List of set bits
*/
public static IntList toList(final BitSet bitSet) {
final IntList list = new IntList();
for (int i = bitSet.nextSetBit(0); i >= 0; i = bitSet.nextSetBit(i + 1)) {
list.add(i);
}
return list;
}
/**
* Converts a bitset to an array.
*
* @param bitSet Bit set
* @return List of set bits
*/
public static Integer[] toArray(final BitSet bitSet) {
final List<Integer> list = toList(bitSet);
return list.toArray(new Integer[list.size()]);
}
/**
* Creates a bitset with given bits set.
*
* <p>For example, {@code of(0, 3)} returns a bit set with bits {0, 3}
* set.
*
* @param bits Array of bits to set
* @return Bit set
*/
public static BitSet of(int... bits) {
final BitSet bitSet = new BitSet();
for (int bit : bits) {
bitSet.set(bit);
}
return bitSet;
}
/**
* Creates a bitset with given bits set.
*
* <p>For example, {@code of(new Integer[] {0, 3})} returns a bit set
* with bits {0, 3} set.
*
* @param bits Array of bits to set
* @return Bit set
*/
public static BitSet of(Integer[] bits) {
final BitSet bitSet = new BitSet();
for (int bit : bits) {
bitSet.set(bit);
}
return bitSet;
}
/**
* Creates a bitset with given bits set.
*
* <p>For example, {@code of(Arrays.asList(0, 3)) } returns a bit set
* with bits {0, 3} set.
*
* @param bits Collection of bits to set
* @return Bit set
*/
public static BitSet of(Collection<? extends Number> bits) {
final BitSet bitSet = new BitSet();
for (Number bit : bits) {
bitSet.set(bit.intValue());
}
return bitSet;
}
/**
* Creates a bitset with bits from {@code fromIndex} (inclusive) to
* specified {@code toIndex} (exclusive) set to {@code true}.
*
* <p>For example, {@code range(0, 3)} returns a bit set with bits
* {0, 1, 2} set.
*
* @param fromIndex Index of the first bit to be set.
* @param toIndex Index after the last bit to be set.
* @return Bit set
*/
public static BitSet range(int fromIndex, int toIndex) {
final BitSet bitSet = new BitSet();
if (toIndex > fromIndex) {
// Avoid http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6222207
// "BitSet internal invariants may be violated"
bitSet.set(fromIndex, toIndex);
}
return bitSet;
}
public static BitSet range(int toIndex) {
return range(0, toIndex);
}
}
// End BitSets.java