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java.util.BitSet implementation
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Zsombor
Joel Dice
parent
2e0ca31148
commit
e1d712ef71
169
classpath/java/util/BitSet.java
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169
classpath/java/util/BitSet.java
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@ -0,0 +1,169 @@
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package java.util;
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import java.io.Serializable;
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/**
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* @author zsombor
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*
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*/
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public class BitSet implements Serializable, Cloneable {
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final static int BITS_PER_LONG = 64;
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final static int BITS_PER_LONG_SHIFT = 6;
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final static long MASK = 0xFFFFFFFFFFFFFFFFL;
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private long[] bits;
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private static int longPosition(int index) {
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return index >> BITS_PER_LONG_SHIFT;
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}
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private static long bitPosition(int index) {
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return 1L << (index % BITS_PER_LONG);
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}
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public BitSet(int bitLength) {
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if (bitLength % BITS_PER_LONG == 0) {
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enlarge(longPosition(bitLength));
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} else {
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enlarge(longPosition(bitLength) + 1);
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}
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}
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public BitSet() {
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enlarge(1);
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}
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public void and(BitSet otherBits) {
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int max = Math.max(bits.length, otherBits.bits.length);
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for (int i = 0; i < max; i++) {
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bits[i] &= otherBits.bits[i];
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}
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}
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public void andNot(BitSet otherBits) {
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int max = Math.max(bits.length, otherBits.bits.length);
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enlarge(max);
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for (int i = 0; i < max; i++) {
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bits[i] &= ~otherBits.bits[i];
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}
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}
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public void or(BitSet otherBits) {
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int max = Math.max(bits.length, otherBits.bits.length);
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enlarge(max);
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for (int i = 0; i < max; i++) {
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bits[i] |= otherBits.bits[i];
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}
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}
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public void xor(BitSet otherBits) {
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int max = Math.max(bits.length, otherBits.bits.length);
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enlarge(max);
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for (int i = 0; i < max; i++) {
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bits[i] ^= otherBits.bits[i];
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}
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}
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private void enlarge(int newSize) {
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if (bits == null || bits.length <= newSize) {
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long[] newBits = new long[newSize + 1];
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if (bits != null) {
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System.arraycopy(bits, 0, newBits, 0, bits.length);
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}
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bits = newBits;
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}
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}
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public void clear(int index) {
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int pos = longPosition(index);
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if (pos < bits.length) {
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bits[pos] &= (MASK ^ bitPosition(index));
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}
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}
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public boolean get(int index) {
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int pos = longPosition(index);
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if (pos < bits.length) {
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return (bits[pos] & bitPosition(index)) != 0;
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}
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return false;
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}
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public void set(int index) {
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int pos = longPosition(index);
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enlarge(pos);
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bits[pos] |= bitPosition(index);
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}
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public void set(int start, int end) {
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for (int i = start; i < end; i++) {
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set(i);
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}
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}
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public void clear(int start, int end) {
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for (int i = start; i < end; i++) {
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clear(i);
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}
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}
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public boolean isEmpty() {
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for (int i = 0; i < bits.length; i++) {
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if (bits[i] != 0) {
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return false;
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}
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}
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return true;
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}
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public boolean intersects(BitSet otherBits) {
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int max = Math.max(bits.length, otherBits.bits.length);
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for (int i = 0; i < max; i++) {
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if ((bits[i] & otherBits.bits[i]) != 0) {
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return true;
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}
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}
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return false;
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}
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public int length() {
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return bits.length << BITS_PER_LONG_SHIFT;
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}
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public int nextSetBit(int fromIndex) {
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return nextBit(fromIndex, false);
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}
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private int nextBit(int fromIndex, boolean bitClear) {
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int pos = longPosition(fromIndex);
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if (pos >= bits.length) {
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return -1;
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}
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int current = fromIndex;
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do {
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long currValue = bits[pos];
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if (currValue == 0) {
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pos++;
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current = pos << BITS_PER_LONG_SHIFT;
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} else {
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do {
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long bitPos = bitPosition(current);
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if (((currValue & bitPos) != 0) ^ bitClear) {
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return current;
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} else {
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current++;
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}
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} while (current % BITS_PER_LONG != 0);
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}
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pos++;
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} while (pos < bits.length);
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return -1;
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}
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public int nextClearBit(int fromIndex) {
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return nextBit(fromIndex, true);
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}
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}
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64
test/BitsetTest.java
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64
test/BitsetTest.java
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@ -0,0 +1,64 @@
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import java.util.BitSet;
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public class BitsetTest {
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public static void main(String[] args) {
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BitSet bits = new BitSet(16);
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bits.set(5);
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bits.set(1);
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BitSet other = new BitSet(16);
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other.set(5);
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assertTrue("bit 1 is set", bits.get(1));
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assertTrue("bit 5 is set", bits.get(5));
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assertTrue("bit 0 is not set", !bits.get(0));
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assertTrue("bit 16 is not set", !bits.get(16));
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bits.and(other);
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assertTrue("bit 5 is set", bits.get(5));
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assertTrue("bit 1 is not set", !bits.get(1));
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bits.set(100);
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assertTrue("bit 100 is set", bits.get(100));
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assertTrue("bit 101 is not set", !bits.get(101));
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other.set(101);
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bits.or(other);
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assertTrue("bit 101 is set", bits.get(101));
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assertEquals("first bit is 5", 5, bits.nextSetBit(0));
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assertEquals("first bit is 5 from 3", 5, bits.nextSetBit(4));
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assertEquals("first bit is 5 from 5", 5, bits.nextSetBit(5));
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assertEquals("second bit is 100", 100, bits.nextSetBit(6));
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assertEquals("second bit is 100 from 100", 100, bits.nextSetBit(100));
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assertEquals("third bit is 101", 101, bits.nextSetBit(101));
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assertEquals("there is no 4th bit", -1, bits.nextSetBit(102));
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assertEquals("first empty bit is 0", 0, bits.nextClearBit(0));
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assertEquals("after 5, 6 is empty", 6, bits.nextClearBit(5));
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assertEquals("after 100, 102 is empty", 102, bits.nextClearBit(100));
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}
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static void assertTrue(String msg, boolean flag) {
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if (flag) {
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System.out.println(msg + " : OK.");
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} else {
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throw new RuntimeException("Error:"+msg);
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}
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}
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static void assertEquals(String msg, int expected, int actual) {
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if (expected==actual) {
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System.out.println(msg + " : OK. ["+actual+']');
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} else {
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throw new RuntimeException("Error:"+msg+" expected:"+expected+", actual:"+actual);
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}
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}
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}
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