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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.
 
 
 /*
 Copyright ï¿½ 1999 CERN - European Organization for Nuclear Research.
 Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose 
 is hereby granted without fee, provided that the above copyright notice appear in all copies and 
 that both that copyright notice and this permission notice appear in supporting documentation. 
 CERN makes no representations about the suitability of this software for any purpose. 
 It is provided "as is" without expressed or implied warranty.
 */
 package org.apache.mahout.math.map;
 
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
Open hash map. This implements Map, but it does not respect several aspects of the Map contract that impose the very sorts of performance penalities that this class exists to avoid. entrySet(), values, and keySet() do not return collections that share storage with the main map, and changes to those returned objects are not reflected in the container.
 
 public class OpenHashMap<K,V> extends AbstractSet implements Map<K,V> {
   protected static final byte FREE = 0;
   protected static final byte FULL = 1;
   protected static final byte REMOVED = 2;
   protected static final Object NO_KEY_VALUE = null;

  
The hash table keys.
 
   protected Object[] table;

  
The hash table values.
 
   protected Object[] values;

  
The state of each hash table entry (FREE, FULL, REMOVED).
 
   protected byte[] state;

  
The number of table entries in state==FREE.
 
   protected int freeEntries;


  
Constructs an empty map with default capacity and default load factors.
 
   public OpenHashMap() {
     this();
   }

  
Constructs an empty map with the specified initial capacity and default load factors.

Parameters:
initialCapacity the initial capacity of the map.
Throws:
java.lang.IllegalArgumentException if the initial capacity is less than zero.
 
   public OpenHashMap(int initialCapacity) {
     this(initialCapacity);
   }

  
Constructs an empty map with the specified initial capacity and the specified minimum and maximum load factor.

Parameters:
initialCapacity the initial capacity.
minLoadFactor the minimum load factor.
maxLoadFactor the maximum load factor.
Throws:
java.lang.IllegalArgumentException if initialCapacity < 0 || (minLoadFactor < 0.0 || minLoadFactor >= 1.0) || (maxLoadFactor <= 0.0 || maxLoadFactor >= 1.0) || (minLoadFactor >= maxLoadFactor).
 
   public OpenHashMap(int initialCapacitydouble minLoadFactordouble maxLoadFactor) {
     setUp(initialCapacityminLoadFactormaxLoadFactor);
   }

  
Removes all (key,value) associations from the receiver. Implicitly calls trimToSize().
 
   @Override
   public void clear() {
    Arrays.fill(this.);
     = 0;
     = .// delta
    trimToSize();
  }

  
Returns a deep copy of the receiver.

Returns:
a deep copy of the receiver.
  @SuppressWarnings("unchecked")
  public Object clone() {
    OpenHashMap<K,V> copy = (OpenHashMap<K,V>) super.clone();
    copy.table = copy.table.clone();
    copy.values = copy.values.clone();
    copy.state = copy.state.clone();
    return copy;
  }

  
Returns true if the receiver contains the specified key.

Returns:
true if the receiver contains the specified key.
  @SuppressWarnings("unchecked")
  public boolean containsKey(Object key) {
    return indexOfKey((K)key) >= 0;
  }

  
Returns true if the receiver contains the specified value.

Returns:
true if the receiver contains the specified value.
  @SuppressWarnings("unchecked")
  public boolean containsValue(Object value) {
    return indexOfValue((V)value) >= 0;
  }

  
Ensures that the receiver can hold at least the specified number of associations without needing to allocate new internal memory. If necessary, allocates new internal memory and increases the capacity of the receiver.

This method never need be called; it is for performance tuning only. Calling this method before put()ing a large number of associations boosts performance, because the receiver will grow only once instead of potentially many times and hash collisions get less probable.

Parameters:
minCapacity the desired minimum capacity.
  public void ensureCapacity(int minCapacity) {
    if (. < minCapacity) {
      int newCapacity = nextPrime(minCapacity);
      rehash(newCapacity);
    }
  }

  
Applies a procedure to each key of the receiver, if any. Note: Iterates over the keys in no particular order. Subclasses can define a particular order, for example, "sorted by key". All methods which can be expressed in terms of this method (most methods can) must guarantee to use the same order defined by this method, even if it is no particular order. This is necessary so that, for example, methods keys and values will yield association pairs, not two uncorrelated lists.

Parameters:
procedure the procedure to be applied. Stops iteration if the procedure returns false, otherwise continues.
Returns:
false if the procedure stopped before all keys where iterated over, true otherwise.
  @SuppressWarnings("unchecked")
  public boolean forEachKey(ObjectProcedure<K> procedure) {
    for (int i = .i-- > 0;) {
      if ([i] ==  && !procedure.apply((K)[i])) {
        return false;
      }
    }
    return true;
  }

  
Applies a procedure to each (key,value) pair of the receiver, if any. Iteration order is guaranteed to be identical to the order used by method forEachKey(org.apache.mahout.math.function.ObjectProcedure).

Parameters:
procedure the procedure to be applied. Stops iteration if the procedure returns false, otherwise continues.
Returns:
false if the procedure stopped before all keys where iterated over, true otherwise.
  @SuppressWarnings("unchecked")
  public boolean forEachPair(ObjectObjectProcedure<K,V> procedure) {
    for (int i = .i-- > 0;) {
      if ([i] ==  && !procedure.apply((K)[i], (V)[i])) {
        return false;
      }
    }
    return true;
  }

  
Returns the value associated with the specified key. It is often a good idea to first check with containsKey(java.lang.Object) whether the given key has a value associated or not, i.e. whether there exists an association for the given key or not.

Parameters:
key the key to be searched for.
Returns:
the value associated with the specified key; 0 if no such key is present.
  @SuppressWarnings("unchecked")
  public V get(Object key) {
    int i = indexOfKey((K)key);
    if (i < 0) {
      return null;
    } //not contained
    return (V)[i];
  }

  

Parameters:
key the key to be added to the receiver.
Returns:
the index where the key would need to be inserted, if it is not already contained. Returns -index-1 if the key is already contained at slot index. Therefore, if the returned index < 0, then it is already contained at slot -index-1. If the returned index >= 0, then it is NOT already contained and should be inserted at slot index.
  protected int indexOfInsertion(K key) {
    Object[] tab = ;
    byte[] stat = ;
    int length = tab.length;
    int hash = key.hashCode() & 0x7FFFFFFF;
    int i = hash % length;
    int decrement = hash % (length - 2); // double hashing, see http://www.eece.unm.edu/faculty/heileman/hash/node4.html
    //int decrement = (hash / length) % length;
    if (decrement == 0) {
      decrement = 1;
    }
    // stop if we find a removed or free slot, or if we find the key itself
    // do NOT skip over removed slots (yes, open addressing is like that...)
    while (stat[i] ==  && !equalsMindTheNull(keytab[i])) {
      i -= decrement;
      //hashCollisions++;
      if (i < 0) {
        i += length;
      }
    }
    if (stat[i] == ) {
      // stop if we find a free slot, or if we find the key itself.
      // do skip over removed slots (yes, open addressing is like that...)
      // assertion: there is at least one FREE slot.
      int j = i;
      while (stat[i] !=  && (stat[i] ==  || tab[i] != key)) {
        i -= decrement;
        //hashCollisions++;
        if (i < 0) {
          i += length;
        }
      }
      if (stat[i] == ) {
        i = j;
      }
    }
    if (stat[i] == ) {
      // key already contained at slot i.
      // return a negative number identifying the slot.
      return -i - 1;
    }
    // not already contained, should be inserted at slot i.
    // return a number >= 0 identifying the slot.
    return i;
  }

  

Parameters:
key the key to be searched in the receiver.
Returns:
the index where the key is contained in the receiver, returns -1 if the key was not found.
  protected int indexOfKey(K key) {
    Object[] tab = ;
    byte[] stat = ;
    int length = tab.length;
    int hash = key.hashCode() & 0x7FFFFFFF;
    int i = hash % length;
    int decrement = hash % (length - 2); // double hashing, see http://www.eece.unm.edu/faculty/heileman/hash/node4.html
    //int decrement = (hash / length) % length;
    if (decrement == 0) {
      decrement = 1;
    }
    // stop if we find a free slot, or if we find the key itself.
    // do skip over removed slots (yes, open addressing is like that...)
    while (stat[i] !=  && (stat[i] ==  || !equalsMindTheNull(keytab[i]))) {
      i -= decrement;
      //hashCollisions++;
      if (i < 0) {
        i += length;
      }
    }
    if (stat[i] == ) {
      return -1;
    } // not found
    return i//found, return index where key is contained
  }

  

Parameters:
value the value to be searched in the receiver.
Returns:
the index where the value is contained in the receiver, returns -1 if the value was not found.
  protected int indexOfValue(V value) {
    Object[] val = ;
    byte[] stat = ;
    for (int i = stat.length; --i >= 0;) {
      if (stat[i] ==  && equalsMindTheNull(val[i], value)) {
        return i;
      }
    }
    return -1; // not found
  }

  
Fills all keys contained in the receiver into the specified list. Fills the list, starting at index 0. After this call returns the specified list has a new size that equals this.size(). This method can be used to iterate over the keys of the receiver.

Parameters:
list the list to be filled, can have any size.
  @SuppressWarnings("unchecked")
  public void keys(List<K> list) {
    list.clear();
  
    Object [] tab = ;
    byte[] stat = ;
    for (int i = tab.lengthi-- > 0;) {
      if (stat[i] == ) {
        list.add((K)tab[i]);
      }
    }
  }

  
Associates the given key with the given value. Replaces any old (key,someOtherValue) association, if existing.

Parameters:
key the key the value shall be associated with.
value the value to be associated.
Returns:
true if the receiver did not already contain such a key; false if the receiver did already contain such a key - the new value has now replaced the formerly associated value.
  @SuppressWarnings("unchecked")
  public V put(K key, V value) {
    int i = indexOfInsertion(key);
    if (i < 0) { //already contained
      i = -i - 1;
      V previous = (V) this.[i];
      this.[i] = value;
      return previous;
    }
    if (this. > this.) {
      int newCapacity = chooseGrowCapacity(this. + 1, this.this.);
      rehash(newCapacity);
      return put(keyvalue);
    }
    this.[i] = key;
    this.[i] = value;
    if (this.[i] == ) {
      this.--;
    }
    this.[i] = ;
    this.++;
    if (this. < 1) { //delta
      int newCapacity = chooseGrowCapacity(this. + 1, this.this.);
      rehash(newCapacity);
    }
    return null;
  }

  
Rehashes the contents of the receiver into a new table with a smaller or larger capacity. This method is called automatically when the number of keys in the receiver exceeds the high water mark or falls below the low water mark.
  @SuppressWarnings("unchecked")
  protected void rehash(int newCapacity) {
    int oldCapacity = .;
    //if (oldCapacity == newCapacity) return;
    Object[] oldTable = ;
    Object[] oldValues = ;
    byte[] oldState = ;
    Object[] newTable = new Object[newCapacity];
    Object[] newValues = new Object[newCapacity];
    byte[] newState = new byte[newCapacity];
    this. = chooseLowWaterMark(newCapacitythis.);
    this. = chooseHighWaterMark(newCapacitythis.);
    this. = newTable;
    this. = newValues;
    this. = newState;
    this. = newCapacity - this.// delta
    for (int i = oldCapacityi-- > 0;) {
      if (oldState[i] == ) {
        Object element = oldTable[i];
        int index = indexOfInsertion((K)element);
        newTable[index] = element;
        newValues[index] = oldValues[i];
        newState[index] = ;
      }
    }
  }

  
Removes the given key with its associated element from the receiver, if present.

Parameters:
key the key to be removed from the receiver.
Returns:
true if the receiver contained the specified key, false otherwise.
  @SuppressWarnings("unchecked")
  public V remove(Object key) {
    int i = indexOfKey((K)key);
    if (i < 0) {
      return null;
    }
    // key not contained
    V removed = (V) [i];
    this.[i] = ;
    //this.values[i]=0; // delta
    this.--;
    if (this. < this.) {
      int newCapacity = chooseShrinkCapacity(this.this.this.);
      rehash(newCapacity);
    }
    return removed;
  }

  
Initializes the receiver.

Parameters:
initialCapacity the initial capacity of the receiver.
minLoadFactor the minLoadFactor of the receiver.
maxLoadFactor the maxLoadFactor of the receiver.
Throws:
java.lang.IllegalArgumentException if initialCapacity < 0 || (minLoadFactor < 0.0 || minLoadFactor >= 1.0) || (maxLoadFactor <= 0.0 || maxLoadFactor >= 1.0) || (minLoadFactor >= maxLoadFactor).
  protected void setUp(int initialCapacitydouble minLoadFactordouble maxLoadFactor) {
    int capacity = initialCapacity;
    super.setUp(capacityminLoadFactormaxLoadFactor);
    capacity = nextPrime(capacity);
    if (capacity == 0) {
      capacity = 1;
    } // open addressing needs at least one FREE slot at any time.
    this. = new Object[capacity];
    this. = new Object[capacity];
    this. = new byte[capacity];
    // memory will be exhausted long before this pathological case happens, anyway.
    this. = minLoadFactor;
    if (capacity == .) {
      this. = 1.0;
    } else {
      this. = maxLoadFactor;
    }
    this. = 0;
    this. = capacity// delta
    // lowWaterMark will be established upon first expansion.
    // establishing it now (upon instance construction) would immediately make the table shrink upon first put(...).
    // After all the idea of an "initialCapacity" implies violating lowWaterMarks when an object is young.
    // See ensureCapacity(...)
    this. = 0;
    this. = chooseHighWaterMark(capacitythis.);
  }

  
Trims the capacity of the receiver to be the receiver's current size. Releases any superfluous internal memory. An application can use this operation to minimize the storage of the receiver.
  public void trimToSize() {
    // * 1.2 because open addressing's performance exponentially degrades beyond that point
    // so that even rehashing the table can take very long
    int newCapacity = nextPrime((int) (1 + 1.2 * size()));
    if (. > newCapacity) {
      rehash(newCapacity);
    }
  }

  
Access for unit tests.

Parameters:
capacity
minLoadFactor
maxLoadFactor
  void getInternalFactors(int[] capacity
      double[] minLoadFactor
      double[] maxLoadFactor) {
    capacity[0] = .;
    minLoadFactor[0] = this.;
    maxLoadFactor[0] = this.;
  }
  private class MapEntry implements Map.Entry<K,V> {
    private final K key;
    private final V value;
    
    MapEntry(K key, V value) {
      this. = key;
      this. = value;
    }
    @Override
    public K getKey() {
      return ;
    }
    @Override
    public V getValue() {
      return ;
    }
    @Override
    public V setValue(V value) {
      throw new UnsupportedOperationException("Map.Entry.setValue not supported for OpenHashMap");
    }
    
  }

  
Allocate a set to contain Map.Entry objects for the pairs and return it.
  public Set<java.util.Map.Entry<K,V>> entrySet() {
    final Set<Entry<K, V>> entries = new OpenHashSet<Map.Entry<K,V>>();
    forEachPair(new ObjectObjectProcedure<K,V>() {
      @Override
      public boolean apply(K key, V value) {
        entries.add(new MapEntry(keyvalue));
        return true;
      }
    });
    return entries;
  }

  
Allocate a set to contain keys and return it. This violates the 'backing' provisions of the map interface.
  public Set<K> keySet() {
    final Set<K> keys = new OpenHashSet<K>();
    forEachKey(new ObjectProcedure<K>() {
      @Override
      public boolean apply(K element) {
        keys.add(element);
        return true;
      }
    });
    return keys;
  }
  public void putAll(Map<? extends K,? extends V> m) {
    for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) {
      put(e.getKey(), e.getValue());
    }
  }

  
Allocate a list to contain the values and return it. This violates the 'backing' provision of the Map interface.
  public Collection<V> values() {
    final List<V> valueList = new ArrayList<V>();
    forEachPair(new ObjectObjectProcedure<K,V>() {
      @Override
      public boolean apply(K key, V value) {
        valueList.add(value);
        return true;
      }
    });
    return valueList;
  }
  @SuppressWarnings("unchecked")
  public boolean equals(Object obj) {
    if (!(obj instanceof OpenHashMap)) {
      return false;
    }
    final OpenHashMap<K,V> o = (OpenHashMap<K,V>) obj;
    if (o.size() != size()) {
      return false;
    }
    final boolean[] equal = new boolean[1];
    equal[0] = true;
    forEachPair(new ObjectObjectProcedure<K,V>() {
      @Override
      public boolean apply(K key, V value) {
        Object ov = o.get(key);
        if (!value.equals(ov)) {
          equal[0] = false;
          return false;
        }
        return true;
      }
    });
    return equal[0];
  }
  public String toString() {
    final StringBuilder sb = new StringBuilder();
    sb.append('{');
    forEachPair(new ObjectObjectProcedure<K,V>() {
      @Override
      public boolean apply(K key, V value) {
        sb.append('[');
        sb.append(key);
        sb.append(" -> ");
        sb.append(value);
        sb.append("] ");
        return true;
      }
    });
    sb.append('}');
    return sb.toString();
  }
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