--- /dev/null
+package org.apache.lucene.util.collections;
+
+import java.util.Arrays;
+import java.util.Iterator;
+
+/**
+ * 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.
+ */
+
+/**
+ * An Array-based hashtable which maps, similar to Java's HashMap, only
+ * performance tests showed it performs better.
+ * <p>
+ * The hashtable is constructed with a given capacity, or 16 as a default. In
+ * case there's not enough room for new pairs, the hashtable grows. Capacity is
+ * adjusted to a power of 2, and there are 2 * capacity entries for the hash.
+ * The pre allocated arrays (for keys, values) are at length of capacity + 1,
+ * where index 0 is used as 'Ground' or 'NULL'.
+ * <p>
+ * The arrays are allocated ahead of hash operations, and form an 'empty space'
+ * list, to which the <key,value> pair is allocated.
+ *
+ * @lucene.experimental
+ */
+public class ArrayHashMap<K,V> implements Iterable<V> {
+
+ /** Implements an IntIterator which iterates over all the allocated indexes. */
+ private final class IndexIterator implements IntIterator {
+ /**
+ * The last used baseHashIndex. Needed for "jumping" from one hash entry
+ * to another.
+ */
+ private int baseHashIndex = 0;
+
+ /** The next not-yet-visited index. */
+ private int index = 0;
+
+ /** Index of the last visited pair. Used in {@link #remove()}. */
+ private int lastIndex = 0;
+
+ /**
+ * Create the Iterator, make <code>index</code> point to the "first"
+ * index which is not empty. If such does not exist (eg. the map is
+ * empty) it would be zero.
+ */
+ public IndexIterator() {
+ for (baseHashIndex = 0; baseHashIndex < baseHash.length; ++baseHashIndex) {
+ index = baseHash[baseHashIndex];
+ if (index != 0) {
+ break;
+ }
+ }
+ }
+
+ public boolean hasNext() {
+ return index != 0;
+ }
+
+ public int next() {
+ // Save the last index visited
+ lastIndex = index;
+
+ // next the index
+ index = next[index];
+
+ // if the next index points to the 'Ground' it means we're done with
+ // the current hash entry and we need to jump to the next one. This
+ // is done until all the hash entries had been visited.
+ while (index == 0 && ++baseHashIndex < baseHash.length) {
+ index = baseHash[baseHashIndex];
+ }
+
+ return lastIndex;
+ }
+
+ @SuppressWarnings("unchecked")
+ public void remove() {
+ ArrayHashMap.this.remove((K) keys[lastIndex]);
+ }
+
+ }
+
+ /** Implements an Iterator, used for iteration over the map's keys. */
+ private final class KeyIterator implements Iterator<K> {
+ private IntIterator iterator = new IndexIterator();
+
+ KeyIterator() { }
+
+ public boolean hasNext() {
+ return iterator.hasNext();
+ }
+
+ @SuppressWarnings("unchecked")
+ public K next() {
+ return (K) keys[iterator.next()];
+ }
+
+ public void remove() {
+ iterator.remove();
+ }
+ }
+
+ /** Implements an Iterator, used for iteration over the map's values. */
+ private final class ValueIterator implements Iterator<V> {
+ private IntIterator iterator = new IndexIterator();
+
+ ValueIterator() { }
+
+ public boolean hasNext() {
+ return iterator.hasNext();
+ }
+
+ @SuppressWarnings("unchecked")
+ public V next() {
+ return (V) values[iterator.next()];
+ }
+
+ public void remove() {
+ iterator.remove();
+ }
+ }
+
+ /** Default capacity - in case no capacity was specified in the constructor */
+ private static final int DEFAULT_CAPACITY = 16;
+
+ /**
+ * Holds the base hash entries. if the capacity is 2^N, than the base hash
+ * holds 2^(N+1).
+ */
+ int[] baseHash;
+
+ /**
+ * The current capacity of the map. Always 2^N and never less than 16. We
+ * never use the zero index. It is needed to improve performance and is also
+ * used as "ground".
+ */
+ private int capacity;
+
+ /**
+ * All objects are being allocated at map creation. Those objects are "free"
+ * or empty. Whenever a new pair comes along, a pair is being "allocated" or
+ * taken from the free-linked list. as this is just a free list.
+ */
+ private int firstEmpty;
+
+ /** hashFactor is always (2^(N+1)) - 1. Used for faster hashing. */
+ private int hashFactor;
+
+ /** Holds the unique keys. */
+ Object[] keys;
+
+ /**
+ * In case of collisions, we implement a double linked list of the colliding
+ * hash's with the following next[] and prev[]. Those are also used to store
+ * the "empty" list.
+ */
+ int[] next;
+
+ private int prev;
+
+ /** Number of currently stored objects in the map. */
+ private int size;
+
+ /** Holds the values. */
+ Object[] values;
+
+ /** Constructs a map with default capacity. */
+ public ArrayHashMap() {
+ this(DEFAULT_CAPACITY);
+ }
+
+ /**
+ * Constructs a map with given capacity. Capacity is adjusted to a native
+ * power of 2, with minimum of 16.
+ *
+ * @param capacity minimum capacity for the map.
+ */
+ public ArrayHashMap(int capacity) {
+ this.capacity = 16;
+ while (this.capacity < capacity) {
+ // Multiply by 2 as long as we're still under the requested capacity
+ this.capacity <<= 1;
+ }
+
+ // As mentioned, we use the first index (0) as 'Ground', so we need the
+ // length of the arrays to be one more than the capacity
+ int arrayLength = this.capacity + 1;
+
+ values = new Object[arrayLength];
+ keys = new Object[arrayLength];
+ next = new int[arrayLength];
+
+ // Hash entries are twice as big as the capacity.
+ int baseHashSize = this.capacity << 1;
+
+ baseHash = new int[baseHashSize];
+
+ // The has factor is 2^M - 1 which is used as an "AND" hashing operator.
+ // {@link #calcBaseHash()}
+ hashFactor = baseHashSize - 1;
+
+ size = 0;
+
+ clear();
+ }
+
+ /**
+ * Adds a pair to the map. Takes the first empty position from the
+ * empty-linked-list's head - {@link firstEmpty}. New pairs are always
+ * inserted to baseHash, and are followed by the old colliding pair.
+ */
+ private void prvt_put(K key, V value) {
+ // Hash entry to which the new pair would be inserted
+ int hashIndex = calcBaseHashIndex(key);
+
+ // 'Allocating' a pair from the "Empty" list.
+ int objectIndex = firstEmpty;
+
+ // Setting data
+ firstEmpty = next[firstEmpty];
+ values[objectIndex] = value;
+ keys[objectIndex] = key;
+
+ // Inserting the new pair as the first node in the specific hash entry
+ next[objectIndex] = baseHash[hashIndex];
+ baseHash[hashIndex] = objectIndex;
+
+ // Announcing a new pair was added!
+ ++size;
+ }
+
+ /** Calculating the baseHash index using the internal internal <code>hashFactor</code>. */
+ protected int calcBaseHashIndex(K key) {
+ return key.hashCode() & hashFactor;
+ }
+
+ /** Empties the map. Generates the "Empty" space list for later allocation. */
+ public void clear() {
+ // Clears the hash entries
+ Arrays.fill(baseHash, 0);
+
+ // Set size to zero
+ size = 0;
+
+ // Mark all array entries as empty. This is done with
+ // <code>firstEmpty</code> pointing to the first valid index (1 as 0 is
+ // used as 'Ground').
+ firstEmpty = 1;
+
+ // And setting all the <code>next[i]</code> to point at
+ // <code>i+1</code>.
+ for (int i = 1; i < capacity;) {
+ next[i] = ++i;
+ }
+
+ // Surly, the last one should point to the 'Ground'.
+ next[capacity] = 0;
+ }
+
+ /** Returns true iff the key exists in the map. */
+ public boolean containsKey(K key) {
+ return find(key) != 0;
+ }
+
+ /** Returns true iff the object exists in the map. */
+ public boolean containsValue(Object o) {
+ for (Iterator<V> iterator = iterator(); iterator.hasNext();) {
+ V object = iterator.next();
+ if (object.equals(o)) {
+ return true;
+ }
+ }
+ return false;
+ }
+
+ /** Returns the index of the given key, or zero if the key wasn't found. */
+ protected int find(K key) {
+ // Calculate the hash entry.
+ int baseHashIndex = calcBaseHashIndex(key);
+
+ // Start from the hash entry.
+ int localIndex = baseHash[baseHashIndex];
+
+ // while the index does not point to the 'Ground'
+ while (localIndex != 0) {
+ // returns the index found in case of of a matching key.
+ if (keys[localIndex].equals(key)) {
+ return localIndex;
+ }
+
+ // next the local index
+ localIndex = next[localIndex];
+ }
+
+ // If we got this far, it could only mean we did not find the key we
+ // were asked for. return 'Ground' index.
+ return 0;
+ }
+
+ /**
+ * Finds the actual index of a given key with it's baseHashIndex. Some methods
+ * use the baseHashIndex. If those call {@link #find()} there's no need to
+ * re-calculate that hash.
+ *
+ * @return the index of the given key, or 0 if the key wasn't found.
+ */
+ private int findForRemove(K key, int baseHashIndex) {
+ // Start from the hash entry.
+ prev = 0;
+ int index = baseHash[baseHashIndex];
+
+ // while the index does not point to the 'Ground'
+ while (index != 0) {
+ // returns the index found in case of of a matching key.
+ if (keys[index].equals(key)) {
+ return index;
+ }
+
+ // next the local index
+ prev = index;
+ index = next[index];
+ }
+
+ // If we got thus far, it could only mean we did not find the key we
+ // were asked for. return 'Ground' index.
+ return prev = 0;
+ }
+
+ /** Returns the object mapped with the given key, or null if the key wasn't found. */
+ @SuppressWarnings("unchecked")
+ public V get(K key) {
+ return (V) values[find(key)];
+ }
+
+ /**
+ * Allocates a new map of double the capacity, and fast-insert the old
+ * key-value pairs.
+ */
+ @SuppressWarnings("unchecked")
+ protected void grow() {
+ ArrayHashMap<K,V> newmap = new ArrayHashMap<K,V>(capacity * 2);
+
+ // Iterates fast over the collection. Any valid pair is put into the new
+ // map without checking for duplicates or if there's enough space for
+ // it.
+ for (IndexIterator iterator = new IndexIterator(); iterator.hasNext();) {
+ int index = iterator.next();
+ newmap.prvt_put((K) keys[index], (V) values[index]);
+ }
+
+ // Copy that's data into this.
+ capacity = newmap.capacity;
+ size = newmap.size;
+ firstEmpty = newmap.firstEmpty;
+ values = newmap.values;
+ keys = newmap.keys;
+ next = newmap.next;
+ baseHash = newmap.baseHash;
+ hashFactor = newmap.hashFactor;
+ }
+
+ /** Returns true iff the map is empty. */
+ public boolean isEmpty() {
+ return size == 0;
+ }
+
+ /** Returns an iterator on the mapped objects. */
+ public Iterator<V> iterator() {
+ return new ValueIterator();
+ }
+
+ /** Returns an iterator on the map keys. */
+ public Iterator<K> keyIterator() {
+ return new KeyIterator();
+ }
+
+ /** Prints the baseHash array, used for debugging purposes. */
+ @SuppressWarnings("unused")
+ private void printBaseHash() {
+ for (int i : baseHash) {
+ System.out.println(i + ".\t" + i);
+ }
+ }
+
+ /**
+ * Inserts the <key,value> pair into the map. If the key already exists,
+ * this method updates the mapped value to the given one, returning the old
+ * mapped value.
+ *
+ * @return the old mapped value, or null if the key didn't exist.
+ */
+ @SuppressWarnings("unchecked")
+ public V put(K key, V e) {
+ // Does key exists?
+ int index = find(key);
+
+ // Yes!
+ if (index != 0) {
+ // Set new data and exit.
+ V old = (V) values[index];
+ values[index] = e;
+ return old;
+ }
+
+ // Is there enough room for a new pair?
+ if (size == capacity) {
+ // No? Than grow up!
+ grow();
+ }
+
+ // Now that everything is set, the pair can be just put inside with no
+ // worries.
+ prvt_put(key, e);
+
+ return null;
+ }
+
+ /**
+ * Removes a <key,value> pair from the map and returns the mapped value,
+ * or null if the none existed.
+ *
+ * @param key used to find the value to remove
+ * @return the removed value or null if none existed.
+ */
+ @SuppressWarnings("unchecked")
+ public V remove(K key) {
+ int baseHashIndex = calcBaseHashIndex(key);
+ int index = findForRemove(key, baseHashIndex);
+ if (index != 0) {
+ // If it is the first in the collision list, we should promote its
+ // next colliding element.
+ if (prev == 0) {
+ baseHash[baseHashIndex] = next[index];
+ }
+
+ next[prev] = next[index];
+ next[index] = firstEmpty;
+ firstEmpty = index;
+ --size;
+ return (V) values[index];
+ }
+
+ return null;
+ }
+
+ /** Returns number of pairs currently in the map. */
+ public int size() {
+ return this.size;
+ }
+
+ /**
+ * Translates the mapped pairs' values into an array of Objects
+ *
+ * @return an object array of all the values currently in the map.
+ */
+ public Object[] toArray() {
+ int j = -1;
+ Object[] array = new Object[size];
+
+ // Iterates over the values, adding them to the array.
+ for (Iterator<V> iterator = iterator(); iterator.hasNext();) {
+ array[++j] = iterator.next();
+ }
+ return array;
+ }
+
+ /**
+ * Translates the mapped pairs' values into an array of V
+ *
+ * @param a the array into which the elements of the list are to be stored, if
+ * it is big enough; otherwise, use as much space as it can.
+ * @return an array containing the elements of the list
+ */
+ public V[] toArray(V[] a) {
+ int j = 0;
+ // Iterates over the values, adding them to the array.
+ for (Iterator<V> iterator = iterator(); j < a.length
+ && iterator.hasNext(); ++j) {
+ a[j] = iterator.next();
+ }
+ if (j < a.length) {
+ a[j] = null;
+ }
+
+ return a;
+ }
+
+ @Override
+ public String toString() {
+ StringBuffer sb = new StringBuffer();
+ sb.append('{');
+ Iterator<K> keyIterator = keyIterator();
+ while (keyIterator.hasNext()) {
+ K key = keyIterator.next();
+ sb.append(key);
+ sb.append('=');
+ sb.append(get(key));
+ if (keyIterator.hasNext()) {
+ sb.append(',');
+ sb.append(' ');
+ }
+ }
+ sb.append('}');
+ return sb.toString();
+ }
+
+ @Override
+ public int hashCode() {
+ return getClass().hashCode() ^ size();
+ }
+
+ @SuppressWarnings("unchecked")
+ @Override
+ public boolean equals(Object o) {
+ ArrayHashMap<K, V> that = (ArrayHashMap<K,V>)o;
+ if (that.size() != this.size()) {
+ return false;
+ }
+
+ Iterator<K> it = keyIterator();
+ while (it.hasNext()) {
+ K key = it.next();
+ V v1 = this.get(key);
+ V v2 = that.get(key);
+ if ((v1 == null && v2 != null) ||
+ (v1 != null && v2 == null) ||
+ (!v1.equals(v2))) {
+ return false;
+ }
+ }
+ return true;
+ }
+}
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fnp / pylucene.git / blobdiff