224 lines
5.3 KiB
Java
224 lines
5.3 KiB
Java
/*******************************************************************************
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* Copyright (c) 2002 - 2006 IBM Corporation.
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* All rights reserved. This program and the accompanying materials
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* are made available under the terms of the Eclipse Public License v1.0
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* which accompanies this distribution, and is available at
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* http://www.eclipse.org/legal/epl-v10.html
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*
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* Contributors:
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* IBM Corporation - initial API and implementation
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*******************************************************************************/
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package com.ibm.wala.util.intset;
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import java.io.Serializable;
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/**
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* Abstract base class for implementations of bitvectors
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*/
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@SuppressWarnings("rawtypes")
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abstract public class BitVectorBase<T extends BitVectorBase> implements Cloneable, Serializable {
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protected final static boolean DEBUG = false;
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protected final static int LOG_BITS_PER_UNIT = 5;
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protected final static int BITS_PER_UNIT = 32;
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protected final static int MASK = 0xffffffff;
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protected final static int LOW_MASK = 0x1f;
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protected int bits[];
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public abstract void set(int bit);
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public abstract void clear(int bit);
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public abstract boolean get(int bit);
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public abstract int length();
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public abstract void and(T other);
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public abstract void andNot(T other);
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public abstract void or(T other);
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public abstract void xor(T other);
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public abstract boolean sameBits(T other);
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public abstract boolean isSubset(T other);
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public abstract boolean intersectionEmpty(T other);
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/**
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* Convert bitIndex to a subscript into the bits[] array.
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*/
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public static int subscript(int bitIndex) {
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return bitIndex >> LOG_BITS_PER_UNIT;
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}
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/**
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* Clears all bits.
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*/
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public final void clearAll() {
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for (int i = 0; i < bits.length; i++) {
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bits[i] = 0;
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}
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}
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@Override
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public int hashCode() {
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int h = 1234;
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for (int i = bits.length - 1; i >= 0;) {
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h ^= bits[i] * (i + 1);
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i--;
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}
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return h;
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}
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/**
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* How many bits are set?
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*/
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public final int populationCount() {
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int count = 0;
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for (int i = 0; i < bits.length; i++) {
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count += Bits.populationCount(bits[i]);
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}
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return count;
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}
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public boolean isZero() {
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int setLength = bits.length;
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for (int i = setLength - 1; i >= 0;) {
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if (bits[i] != 0)
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return false;
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i--;
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}
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return true;
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}
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@Override
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@SuppressWarnings("unchecked")
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public Object clone() {
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BitVectorBase<T> result = null;
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try {
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result = (BitVectorBase<T>) super.clone();
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} catch (CloneNotSupportedException e) {
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// this shouldn't happen, since we are Cloneable
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throw new InternalError();
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}
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result.bits = new int[bits.length];
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System.arraycopy(bits, 0, result.bits, 0, result.bits.length);
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return result;
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}
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@Override
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public String toString() {
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StringBuffer buffer = new StringBuffer();
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boolean needSeparator = false;
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buffer.append('{');
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int limit = length();
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for (int i = 0; i < limit; i++) {
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if (get(i)) {
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if (needSeparator) {
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buffer.append(", ");
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} else {
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needSeparator = true;
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}
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buffer.append(i);
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}
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}
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buffer.append('}');
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return buffer.toString();
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}
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/*
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* @see com.ibm.wala.util.intset.IntSet#contains(int)
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*/
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public boolean contains(int i) {
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return get(i);
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}
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private static final int[][] masks = new int[][] {
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{ 0xFFFF0000 },
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{ 0xFF000000, 0x0000FF00 },
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{ 0xF0000000, 0x00F00000, 0x0000F000, 0x000000F0 },
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{ 0xC0000000, 0x0C000000, 0x00C00000, 0x000C0000, 0x0000C000, 0x00000C00, 0x000000C0, 0x0000000C },
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{ 0x80000000, 0x20000000, 0x08000000, 0x02000000, 0x00800000, 0x00200000, 0x00080000, 0x00020000, 0x00008000, 0x00002000,
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0x00000800, 0x00000200, 0x00000080, 0x00000020, 0x00000008, 0x00000002 } };
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public int max() {
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int lastWord = bits.length - 1;
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while (lastWord >= 0 && bits[lastWord] == 0)
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lastWord--;
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if (lastWord < 0)
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return -1;
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int count = lastWord * BITS_PER_UNIT;
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int top = bits[lastWord];
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int j = 0;
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for (int i = 0; i < masks.length; i++) {
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if ((top & masks[i][j]) != 0) {
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j <<= 1;
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} else {
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j <<= 1;
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j++;
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}
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}
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return count + (31 - j);
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}
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/**
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* @return min j >= start s.t get(j)
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*/
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public int nextSetBit(int start) {
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if (start < 0) {
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throw new IllegalArgumentException("illegal start: " + start);
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}
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int word = subscript(start);
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int bit = (1 << (start & LOW_MASK));
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while (word < bits.length) {
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if (bits[word] != 0) {
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do {
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if ((bits[word] & bit) != 0)
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return start;
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bit <<= 1;
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start++;
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} while (bit != 0);
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} else {
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start += (BITS_PER_UNIT - (start & LOW_MASK));
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}
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word++;
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bit = 1;
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}
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return -1;
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}
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/**
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* Copies the values of the bits in the specified set into this set.
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*
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* @param set the bit set to copy the bits from
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* @throws IllegalArgumentException if set is null
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*/
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public void copyBits(BitVectorBase set) {
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if (set == null) {
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throw new IllegalArgumentException("set is null");
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}
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int setLength = set.bits.length;
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bits = new int[setLength];
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for (int i = setLength - 1; i >= 0;) {
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bits[i] = set.bits[i];
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i--;
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}
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}
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}
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