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org.htmlunit.corejs.javascript.ObjToIntMap Maven / Gradle / Ivy
/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.htmlunit.corejs.javascript;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
/**
* Map to associate objects to integers. The map does not synchronize any of its operation, so
* either use it from a single thread or do own synchronization or perform all mutation operations
* on one thread before passing the map to others
*
* @author Igor Bukanov
*/
@SuppressWarnings("unused")
public class ObjToIntMap implements Serializable {
private static final long serialVersionUID = -1542220580748809402L;
// Map implementation via hashtable,
// follows "The Art of Computer Programming" by Donald E. Knuth
// ObjToIntMap is a copy cat of ObjToIntMap with API adjusted to object keys
public static class Iterator {
Iterator(ObjToIntMap master) {
this.master = master;
}
final void init(Object[] keys, int[] values, int keyCount) {
this.keys = keys;
this.values = values;
this.cursor = -1;
this.remaining = keyCount;
}
public void start() {
master.initIterator(this);
next();
}
public boolean done() {
return remaining < 0;
}
public void next() {
if (remaining == -1) Kit.codeBug();
if (remaining == 0) {
remaining = -1;
cursor = -1;
} else {
for (++cursor; ; ++cursor) {
Object key = keys[cursor];
if (key != null && key != DELETED) {
--remaining;
break;
}
}
}
}
public Object getKey() {
Object key = keys[cursor];
if (key == UniqueTag.NULL_VALUE) {
key = null;
}
return key;
}
public int getValue() {
return values[cursor];
}
public void setValue(int value) {
values[cursor] = value;
}
ObjToIntMap master;
private int cursor;
private int remaining;
private Object[] keys;
private int[] values;
}
public ObjToIntMap() {
this(4);
}
public ObjToIntMap(int keyCountHint) {
if (keyCountHint < 0) Kit.codeBug();
// Table grow when number of stored keys >= 3/4 of max capacity
int minimalCapacity = keyCountHint * 4 / 3;
int i;
for (i = 2; (1 << i) < minimalCapacity; ++i) {}
power = i;
if (check && power < 2) Kit.codeBug();
}
public boolean isEmpty() {
return keyCount == 0;
}
public int size() {
return keyCount;
}
public boolean has(Object key) {
if (key == null) {
key = UniqueTag.NULL_VALUE;
}
return 0 <= findIndex(key);
}
/**
* Get integer value assigned with key.
*
* @return key integer value or defaultValue if key is absent
*/
public int get(Object key, int defaultValue) {
if (key == null) {
key = UniqueTag.NULL_VALUE;
}
int index = findIndex(key);
if (0 <= index) {
return values[index];
}
return defaultValue;
}
/**
* Get integer value assigned with key.
*
* @return key integer value
* @throws RuntimeException if key does not exist
*/
public int getExisting(Object key) {
if (key == null) {
key = UniqueTag.NULL_VALUE;
}
int index = findIndex(key);
if (0 <= index) {
return values[index];
}
// Key must exist
Kit.codeBug();
return 0;
}
public void put(Object key, int value) {
if (key == null) {
key = UniqueTag.NULL_VALUE;
}
int index = ensureIndex(key);
values[index] = value;
}
/**
* If table already contains a key that equals to keyArg, return that key while setting its
* value to zero, otherwise add keyArg with 0 value to the table and return it.
*/
public Object intern(Object keyArg) {
boolean nullKey = false;
if (keyArg == null) {
nullKey = true;
keyArg = UniqueTag.NULL_VALUE;
}
int index = ensureIndex(keyArg);
values[index] = 0;
return (nullKey) ? null : keys[index];
}
public void remove(Object key) {
if (key == null) {
key = UniqueTag.NULL_VALUE;
}
int index = findIndex(key);
if (0 <= index) {
keys[index] = DELETED;
--keyCount;
}
}
public void clear() {
int i = keys.length;
while (i != 0) {
keys[--i] = null;
}
keyCount = 0;
occupiedCount = 0;
}
public Iterator newIterator() {
return new Iterator(this);
}
// The sole purpose of the method is to avoid accessing private fields
// from the Iterator inner class to workaround JDK 1.1 compiler bug which
// generates code triggering VerifierError on recent JVMs
final void initIterator(Iterator i) {
i.init(keys, values, keyCount);
}
/** Return array of present keys */
public Object[] getKeys() {
Object[] array = new Object[keyCount];
getKeys(array, 0);
return array;
}
public void getKeys(Object[] array, int offset) {
int count = keyCount;
for (int i = 0; count != 0; ++i) {
Object key = keys[i];
if (key != null && key != DELETED) {
if (key == UniqueTag.NULL_VALUE) {
key = null;
}
array[offset] = key;
++offset;
--count;
}
}
}
private static int tableLookupStep(int fraction, int mask, int power) {
int shift = 32 - 2 * power;
if (shift >= 0) {
return ((fraction >>> shift) & mask) | 1;
}
return (fraction & (mask >>> -shift)) | 1;
}
private int findIndex(Object key) {
if (keys != null) {
int hash = key.hashCode();
int fraction = hash * A;
int index = fraction >>> (32 - power);
Object test = keys[index];
if (test != null) {
int N = 1 << power;
if (test == key || (values[N + index] == hash && test.equals(key))) {
return index;
}
// Search in table after first failed attempt
int mask = N - 1;
int step = tableLookupStep(fraction, mask, power);
int n = 0;
for (; ; ) {
if (check) {
if (n >= occupiedCount) Kit.codeBug();
++n;
}
index = (index + step) & mask;
test = keys[index];
if (test == null) {
break;
}
if (test == key || (values[N + index] == hash && test.equals(key))) {
return index;
}
}
}
}
return -1;
}
// Insert key that is not present to table without deleted entries
// and enough free space
private int insertNewKey(Object key, int hash) {
if (check && occupiedCount != keyCount) Kit.codeBug();
if (check && keyCount == 1 << power) Kit.codeBug();
int fraction = hash * A;
int index = fraction >>> (32 - power);
int N = 1 << power;
if (keys[index] != null) {
int mask = N - 1;
int step = tableLookupStep(fraction, mask, power);
int firstIndex = index;
do {
if (check && keys[index] == DELETED) Kit.codeBug();
index = (index + step) & mask;
if (check && firstIndex == index) Kit.codeBug();
} while (keys[index] != null);
}
keys[index] = key;
values[N + index] = hash;
++occupiedCount;
++keyCount;
return index;
}
private void rehashTable() {
if (keys == null) {
if (check && keyCount != 0) Kit.codeBug();
if (check && occupiedCount != 0) Kit.codeBug();
int N = 1 << power;
keys = new Object[N];
values = new int[2 * N];
} else {
// Check if removing deleted entries would free enough space
if (keyCount * 2 >= occupiedCount) {
// Need to grow: less then half of deleted entries
++power;
}
int N = 1 << power;
Object[] oldKeys = keys;
int[] oldValues = values;
int oldN = oldKeys.length;
keys = new Object[N];
values = new int[2 * N];
int remaining = keyCount;
occupiedCount = keyCount = 0;
for (int i = 0; remaining != 0; ++i) {
Object key = oldKeys[i];
if (key != null && key != DELETED) {
int keyHash = oldValues[oldN + i];
int index = insertNewKey(key, keyHash);
values[index] = oldValues[i];
--remaining;
}
}
}
}
// Ensure key index creating one if necessary
private int ensureIndex(Object key) {
int hash = key.hashCode();
int index = -1;
int firstDeleted = -1;
if (keys != null) {
int fraction = hash * A;
index = fraction >>> (32 - power);
Object test = keys[index];
if (test != null) {
int N = 1 << power;
if (test == key || (values[N + index] == hash && test.equals(key))) {
return index;
}
if (test == DELETED) {
firstDeleted = index;
}
// Search in table after first failed attempt
int mask = N - 1;
int step = tableLookupStep(fraction, mask, power);
int n = 0;
for (; ; ) {
if (check) {
if (n >= occupiedCount) Kit.codeBug();
++n;
}
index = (index + step) & mask;
test = keys[index];
if (test == null) {
break;
}
if (test == key || (values[N + index] == hash && test.equals(key))) {
return index;
}
if (test == DELETED && firstDeleted < 0) {
firstDeleted = index;
}
}
}
}
// Inserting of new key
if (check && keys != null && keys[index] != null) Kit.codeBug();
if (firstDeleted >= 0) {
index = firstDeleted;
} else {
// Need to consume empty entry: check occupation level
if (keys == null || occupiedCount * 4 >= (1 << power) * 3) {
// Too litle unused entries: rehash
rehashTable();
return insertNewKey(key, hash);
}
++occupiedCount;
}
keys[index] = key;
values[(1 << power) + index] = hash;
++keyCount;
return index;
}
private void writeObject(ObjectOutputStream out) throws IOException {
out.defaultWriteObject();
int count = keyCount;
for (int i = 0; count != 0; ++i) {
Object key = keys[i];
if (key != null && key != DELETED) {
--count;
out.writeObject(key);
out.writeInt(values[i]);
}
}
}
private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
in.defaultReadObject();
int writtenKeyCount = keyCount;
if (writtenKeyCount != 0) {
keyCount = 0;
int N = 1 << power;
keys = new Object[N];
values = new int[2 * N];
for (int i = 0; i != writtenKeyCount; ++i) {
Object key = in.readObject();
int hash = key.hashCode();
int index = insertNewKey(key, hash);
values[index] = in.readInt();
}
}
}
// A == golden_ratio * (1 << 32) = ((sqrt(5) - 1) / 2) * (1 << 32)
// See Knuth etc.
private static final int A = 0x9e3779b9;
private static final Object DELETED = new Object();
// Structure of kyes and values arrays (N == 1 << power):
// keys[0 <= i < N]: key value or null or DELETED mark
// values[0 <= i < N]: value of key at keys[i]
// values[N <= i < 2*N]: hash code of key at keys[i-N]
private transient Object[] keys;
private transient int[] values;
private int power;
private int keyCount;
private transient int occupiedCount; // == keyCount + deleted_count
// If true, enables consitency checks
private static final boolean check = false;
/* TEST START
public static void main(String[] args) {
if (!check) {
System.err.println("Set check to true and re-run");
throw new RuntimeException("Set check to true and re-run");
}
ObjToIntMap map;
map = new ObjToIntMap(0);
testHash(map, 3);
map = new ObjToIntMap(0);
testHash(map, 10 * 1000);
map = new ObjToIntMap();
testHash(map, 10 * 1000);
map = new ObjToIntMap(30 * 1000);
testHash(map, 10 * 100);
map.clear();
testHash(map, 4);
map = new ObjToIntMap(0);
testHash(map, 10 * 100);
}
private static void testHash(ObjToIntMap map, int N) {
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
check(-1 == map.get(key, -1));
map.put(key, i);
check(i == map.get(key, -1));
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
map.put(key, i);
check(i == map.get(key, -1));
}
check(map.size() == N);
System.out.print("."); System.out.flush();
Object[] keys = map.getKeys();
check(keys.length == N);
for (int i = 0; i != N; ++i) {
Object key = keys[i];
check(map.has(key));
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
check(i == map.get(key, -1));
}
int Nsqrt = -1;
for (int i = 0; ; ++i) {
if (i * i >= N) {
Nsqrt = i;
break;
}
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i * i);
map.put(key, i);
check(i == map.get(key, -1));
}
check(map.size() == 2 * N - Nsqrt);
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i * i);
check(i == map.get(key, -1));
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(-1 - i * i);
map.put(key, i);
check(i == map.get(key, -1));
}
check(map.size() == 3 * N - Nsqrt);
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(-1 - i * i);
map.remove(key);
check(!map.has(key));
}
check(map.size() == 2 * N - Nsqrt);
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i * i);
check(i == map.get(key, -1));
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
int j = intSqrt(i);
if (j * j == i) {
check(j == map.get(key, -1));
}else {
check(i == map.get(key, -1));
}
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i * i);
map.remove(key);
check(-2 == map.get(key, -2));
}
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
map.put(key, i);
check(i == map.get(key, -2));
}
check(map.size() == N);
System.out.print("."); System.out.flush();
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
check(i == map.get(key, -1));
}
System.out.print("."); System.out.flush();
ObjToIntMap copy = (ObjToIntMap)writeAndRead(map);
check(copy.size() == N);
for (int i = 0; i != N; ++i) {
Object key = testKey(i);
check(i == copy.get(key, -1));
}
System.out.print("."); System.out.flush();
checkSameMaps(copy, map);
System.out.println(); System.out.flush();
}
private static void checkSameMaps(ObjToIntMap map1, ObjToIntMap map2) {
check(map1.size() == map2.size());
Object[] keys = map1.getKeys();
check(keys.length == map1.size());
for (int i = 0; i != keys.length; ++i) {
check(map1.get(keys[i], -1) == map2.get(keys[i], -1));
}
}
private static void check(boolean condition) {
if (!condition) Kit.codeBug();
}
private static Object[] testPool;
private static Object testKey(int i) {
int MAX_POOL = 100;
if (0 <= i && i < MAX_POOL) {
if (testPool != null && testPool[i] != null) {
return testPool[i];
}
}
Object x = Double.valueOf(i + 0.5);
if (0 <= i && i < MAX_POOL) {
if (testPool == null) {
testPool = new Object[MAX_POOL];
}
testPool[i] = x;
}
return x;
}
private static int intSqrt(int i) {
int approx = (int)Math.sqrt(i) + 1;
while (approx * approx > i) {
--approx;
}
return approx;
}
private static Object writeAndRead(Object obj) {
try {
java.io.ByteArrayOutputStream
bos = new java.io.ByteArrayOutputStream();
java.io.ObjectOutputStream
out = new java.io.ObjectOutputStream(bos);
out.writeObject(obj);
out.close();
byte[] data = bos.toByteArray();
java.io.ByteArrayInputStream
bis = new java.io.ByteArrayInputStream(data);
java.io.ObjectInputStream
in = new java.io.ObjectInputStream(bis);
Object result = in.readObject();
in.close();
return result;
}catch (Exception ex) {
throw new RuntimeException("Unexpected");
}
}
// TEST END */
}
