From 393911c9cfd511c73272eae75f1d15ec88aa3019 Mon Sep 17 00:00:00 2001 From: Brian Pellin Date: Sat, 28 Jul 2012 17:18:01 -0500 Subject: [PATCH] Add ReferenceMap from Apache collections. --- LICENSE | 18 + .../commons/collections/IterableMap.java | 62 + .../apache/commons/collections/KeyValue.java | 47 + .../commons/collections/MapIterator.java | 109 ++ .../collections/ResettableIterator.java | 39 + .../iterators/AbstractEmptyIterator.java | 90 ++ .../collections/iterators/EmptyIterator.java | 55 + .../iterators/EmptyMapIterator.java | 45 + .../keyvalue/AbstractKeyValue.java | 83 + .../keyvalue/AbstractMapEntry.java | 95 ++ .../collections/keyvalue/DefaultMapEntry.java | 67 + .../collections/map/AbstractHashedMap.java | 1329 +++++++++++++++++ .../collections/map/AbstractReferenceMap.java | 981 ++++++++++++ .../commons/collections/map/ReferenceMap.java | 169 +++ 14 files changed, 3189 insertions(+) create mode 100644 src/org/apache/commons/collections/IterableMap.java create mode 100644 src/org/apache/commons/collections/KeyValue.java create mode 100644 src/org/apache/commons/collections/MapIterator.java create mode 100644 src/org/apache/commons/collections/ResettableIterator.java create mode 100644 src/org/apache/commons/collections/iterators/AbstractEmptyIterator.java create mode 100644 src/org/apache/commons/collections/iterators/EmptyIterator.java create mode 100644 src/org/apache/commons/collections/iterators/EmptyMapIterator.java create mode 100644 src/org/apache/commons/collections/keyvalue/AbstractKeyValue.java create mode 100644 src/org/apache/commons/collections/keyvalue/AbstractMapEntry.java create mode 100644 src/org/apache/commons/collections/keyvalue/DefaultMapEntry.java create mode 100644 src/org/apache/commons/collections/map/AbstractHashedMap.java create mode 100644 src/org/apache/commons/collections/map/AbstractReferenceMap.java create mode 100644 src/org/apache/commons/collections/map/ReferenceMap.java diff --git a/LICENSE b/LICENSE index a574ebc7d..af5c975ce 100644 --- a/LICENSE +++ b/LICENSE @@ -2,6 +2,24 @@ The KeePass icon was created by Francis Jacquerye and is licensed under the terms of the GPLv2 or GPLv3. + +--- + +Files under src/org/apache/* + + 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. + --- Files under src/org/bouncycaste1x/*: diff --git a/src/org/apache/commons/collections/IterableMap.java b/src/org/apache/commons/collections/IterableMap.java new file mode 100644 index 000000000..b409c85c7 --- /dev/null +++ b/src/org/apache/commons/collections/IterableMap.java @@ -0,0 +1,62 @@ +/* + * 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. + */ +package org.apache.commons.collections; + +import java.util.Map; + +/** + * Defines a map that can be iterated directly without needing to create an entry set. + *

+ * A map iterator is an efficient way of iterating over maps. + * There is no need to access the entry set or cast to Map Entry objects. + * 

+ * IterableMap map = new HashedMap();
+ * MapIterator it = map.mapIterator();
+ * while (it.hasNext()) {
+ *   Object key = it.next();
+ *   Object value = it.getValue();
+ *   it.setValue("newValue");
+ * }
+ *
+ * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +public interface IterableMap extends Map { + + /** + * Obtains a MapIterator over the map. + *

+ * A map iterator is an efficient way of iterating over maps. + * There is no need to access the entry set or cast to Map Entry objects. + * 

+     * IterableMap map = new HashedMap();
+     * MapIterator it = map.mapIterator();
+     * while (it.hasNext()) {
+     *   Object key = it.next();
+     *   Object value = it.getValue();
+     *   it.setValue("newValue");
+     * }
+     *
+ * + * @return a map iterator + */ + MapIterator mapIterator(); + +} diff --git a/src/org/apache/commons/collections/KeyValue.java b/src/org/apache/commons/collections/KeyValue.java new file mode 100644 index 000000000..e38c3aba8 --- /dev/null +++ b/src/org/apache/commons/collections/KeyValue.java @@ -0,0 +1,47 @@ +/* + * 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. + */ +package org.apache.commons.collections; + +/** + * Defines a simple key value pair. + *

+ * A Map Entry has considerable additional semantics over and above a simple + * key-value pair. This interface defines the minimum key value, with just the + * two get methods. + * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +public interface KeyValue { + + /** + * Gets the key from the pair. + * + * @return the key + */ + Object getKey(); + + /** + * Gets the value from the pair. + * + * @return the value + */ + Object getValue(); + +} diff --git a/src/org/apache/commons/collections/MapIterator.java b/src/org/apache/commons/collections/MapIterator.java new file mode 100644 index 000000000..a886189b5 --- /dev/null +++ b/src/org/apache/commons/collections/MapIterator.java @@ -0,0 +1,109 @@ +/* + * 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. + */ +package org.apache.commons.collections; + +import java.util.Iterator; + +/** + * Defines an iterator that operates over a Map. + *

+ * This iterator is a special version designed for maps. It can be more + * efficient to use this rather than an entry set iterator where the option + * is available, and it is certainly more convenient. + *

+ * A map that provides this interface may not hold the data internally using + * Map Entry objects, thus this interface can avoid lots of object creation. + *

+ * In use, this iterator iterates through the keys in the map. After each call + * to next(), the getValue() method provides direct + * access to the value. The value can also be set using setValue(). + * 

+ * MapIterator it = map.mapIterator();
+ * while (it.hasNext()) {
+ *   Object key = it.next();
+ *   Object value = it.getValue();
+ *   it.setValue(newValue);
+ * }
+ *
+ * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +public interface MapIterator extends Iterator { + + /** + * Checks to see if there are more entries still to be iterated. + * + * @return true if the iterator has more elements + */ + boolean hasNext(); + + /** + * Gets the next key from the Map. + * + * @return the next key in the iteration + * @throws java.util.NoSuchElementException if the iteration is finished + */ + Object next(); + + //----------------------------------------------------------------------- + /** + * Gets the current key, which is the key returned by the last call + * to next(). + * + * @return the current key + * @throws IllegalStateException if next() has not yet been called + */ + Object getKey(); + + /** + * Gets the current value, which is the value associated with the last key + * returned by next(). + * + * @return the current value + * @throws IllegalStateException if next() has not yet been called + */ + Object getValue(); + + //----------------------------------------------------------------------- + /** + * Removes the last returned key from the underlying Map (optional operation). + *

+ * This method can be called once per call to next(). + * + * @throws UnsupportedOperationException if remove is not supported by the map + * @throws IllegalStateException if next() has not yet been called + * @throws IllegalStateException if remove() has already been called + * since the last call to next() + */ + void remove(); + + /** + * Sets the value associated with the current key (optional operation). + * + * @param value the new value + * @return the previous value + * @throws UnsupportedOperationException if setValue is not supported by the map + * @throws IllegalStateException if next() has not yet been called + * @throws IllegalStateException if remove() has been called since the + * last call to next() + */ + Object setValue(Object value); + +} diff --git a/src/org/apache/commons/collections/ResettableIterator.java b/src/org/apache/commons/collections/ResettableIterator.java new file mode 100644 index 000000000..21baaef9c --- /dev/null +++ b/src/org/apache/commons/collections/ResettableIterator.java @@ -0,0 +1,39 @@ +/* + * 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. + */ +package org.apache.commons.collections; + +import java.util.Iterator; + +/** + * Defines an iterator that can be reset back to an initial state. + *

+ * This interface allows an iterator to be repeatedly reused. + * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +public interface ResettableIterator extends Iterator { + + /** + * Resets the iterator back to the position at which the iterator + * was created. + */ + public void reset(); + +} diff --git a/src/org/apache/commons/collections/iterators/AbstractEmptyIterator.java b/src/org/apache/commons/collections/iterators/AbstractEmptyIterator.java new file mode 100644 index 000000000..632eff787 --- /dev/null +++ b/src/org/apache/commons/collections/iterators/AbstractEmptyIterator.java @@ -0,0 +1,90 @@ +/* + * 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. + */ +package org.apache.commons.collections.iterators; + +import java.util.NoSuchElementException; + +/** + * Provides an implementation of an empty iterator. + * + * @since Commons Collections 3.1 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +abstract class AbstractEmptyIterator { + + /** + * Constructor. + */ + protected AbstractEmptyIterator() { + super(); + } + + public boolean hasNext() { + return false; + } + + public Object next() { + throw new NoSuchElementException("Iterator contains no elements"); + } + + public boolean hasPrevious() { + return false; + } + + public Object previous() { + throw new NoSuchElementException("Iterator contains no elements"); + } + + public int nextIndex() { + return 0; + } + + public int previousIndex() { + return -1; + } + + public void add(Object obj) { + throw new UnsupportedOperationException("add() not supported for empty Iterator"); + } + + public void set(Object obj) { + throw new IllegalStateException("Iterator contains no elements"); + } + + public void remove() { + throw new IllegalStateException("Iterator contains no elements"); + } + + public Object getKey() { + throw new IllegalStateException("Iterator contains no elements"); + } + + public Object getValue() { + throw new IllegalStateException("Iterator contains no elements"); + } + + public Object setValue(Object value) { + throw new IllegalStateException("Iterator contains no elements"); + } + + public void reset() { + // do nothing + } + +} diff --git a/src/org/apache/commons/collections/iterators/EmptyIterator.java b/src/org/apache/commons/collections/iterators/EmptyIterator.java new file mode 100644 index 000000000..30dc4edde --- /dev/null +++ b/src/org/apache/commons/collections/iterators/EmptyIterator.java @@ -0,0 +1,55 @@ +/* + * 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. + */ +package org.apache.commons.collections.iterators; + +import java.util.Iterator; + +import org.apache.commons.collections.ResettableIterator; + +/** + * Provides an implementation of an empty iterator. + *

+ * This class provides an implementation of an empty iterator. + * This class provides for binary compatability between Commons Collections + * 2.1.1 and 3.1 due to issues with IteratorUtils. + * + * @since Commons Collections 2.1.1 and 3.1 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +public class EmptyIterator extends AbstractEmptyIterator implements ResettableIterator { + + /** + * Singleton instance of the iterator. + * @since Commons Collections 3.1 + */ + public static final ResettableIterator RESETTABLE_INSTANCE = new EmptyIterator(); + /** + * Singleton instance of the iterator. + * @since Commons Collections 2.1.1 and 3.1 + */ + public static final Iterator INSTANCE = RESETTABLE_INSTANCE; + + /** + * Constructor. + */ + protected EmptyIterator() { + super(); + } + +} diff --git a/src/org/apache/commons/collections/iterators/EmptyMapIterator.java b/src/org/apache/commons/collections/iterators/EmptyMapIterator.java new file mode 100644 index 000000000..c0fc7ff7c --- /dev/null +++ b/src/org/apache/commons/collections/iterators/EmptyMapIterator.java @@ -0,0 +1,45 @@ +/* + * 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. + */ +package org.apache.commons.collections.iterators; + +import org.apache.commons.collections.MapIterator; +import org.apache.commons.collections.ResettableIterator; + +/** + * Provides an implementation of an empty map iterator. + * + * @since Commons Collections 3.1 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Stephen Colebourne + */ +public class EmptyMapIterator extends AbstractEmptyIterator implements MapIterator, ResettableIterator { + + /** + * Singleton instance of the iterator. + * @since Commons Collections 3.1 + */ + public static final MapIterator INSTANCE = new EmptyMapIterator(); + + /** + * Constructor. + */ + protected EmptyMapIterator() { + super(); + } + +} diff --git a/src/org/apache/commons/collections/keyvalue/AbstractKeyValue.java b/src/org/apache/commons/collections/keyvalue/AbstractKeyValue.java new file mode 100644 index 000000000..ba4e6f508 --- /dev/null +++ b/src/org/apache/commons/collections/keyvalue/AbstractKeyValue.java @@ -0,0 +1,83 @@ +/* + * 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. + */ +package org.apache.commons.collections.keyvalue; + +import org.apache.commons.collections.KeyValue; + +/** + * Abstract pair class to assist with creating KeyValue + * and {@link java.util.Map.Entry Map.Entry} implementations. + * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author James Strachan + * @author Michael A. Smith + * @author Neil O'Toole + * @author Stephen Colebourne + */ +public abstract class AbstractKeyValue implements KeyValue { + + /** The key */ + protected Object key; + /** The value */ + protected Object value; + + /** + * Constructs a new pair with the specified key and given value. + * + * @param key the key for the entry, may be null + * @param value the value for the entry, may be null + */ + protected AbstractKeyValue(Object key, Object value) { + super(); + this.key = key; + this.value = value; + } + + /** + * Gets the key from the pair. + * + * @return the key + */ + public Object getKey() { + return key; + } + + /** + * Gets the value from the pair. + * + * @return the value + */ + public Object getValue() { + return value; + } + + /** + * Gets a debugging String view of the pair. + * + * @return a String view of the entry + */ + public String toString() { + return new StringBuffer() + .append(getKey()) + .append('=') + .append(getValue()) + .toString(); + } + +} diff --git a/src/org/apache/commons/collections/keyvalue/AbstractMapEntry.java b/src/org/apache/commons/collections/keyvalue/AbstractMapEntry.java new file mode 100644 index 000000000..10c056a16 --- /dev/null +++ b/src/org/apache/commons/collections/keyvalue/AbstractMapEntry.java @@ -0,0 +1,95 @@ +/* + * 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. + */ +package org.apache.commons.collections.keyvalue; + +import java.util.Map; + +/** + * Abstract Pair class to assist with creating correct + * {@link java.util.Map.Entry Map.Entry} implementations. + * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author James Strachan + * @author Michael A. Smith + * @author Neil O'Toole + * @author Stephen Colebourne + */ +public abstract class AbstractMapEntry extends AbstractKeyValue implements Map.Entry { + + /** + * Constructs a new entry with the given key and given value. + * + * @param key the key for the entry, may be null + * @param value the value for the entry, may be null + */ + protected AbstractMapEntry(Object key, Object value) { + super(key, value); + } + + // Map.Entry interface + //------------------------------------------------------------------------- + /** + * Sets the value stored in this Map.Entry. + *

+ * This Map.Entry is not connected to a Map, so only the + * local data is changed. + * + * @param value the new value + * @return the previous value + */ + public Object setValue(Object value) { + Object answer = this.value; + this.value = value; + return answer; + } + + /** + * Compares this Map.Entry with another Map.Entry. + *

+ * Implemented per API documentation of {@link java.util.Map.Entry#equals(Object)} + * + * @param obj the object to compare to + * @return true if equal key and value + */ + public boolean equals(Object obj) { + if (obj == this) { + return true; + } + if (obj instanceof Map.Entry == false) { + return false; + } + Map.Entry other = (Map.Entry) obj; + return + (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey())) && + (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue())); + } + + /** + * Gets a hashCode compatible with the equals method. + *

+ * Implemented per API documentation of {@link java.util.Map.Entry#hashCode()} + * + * @return a suitable hash code + */ + public int hashCode() { + return (getKey() == null ? 0 : getKey().hashCode()) ^ + (getValue() == null ? 0 : getValue().hashCode()); + } + +} diff --git a/src/org/apache/commons/collections/keyvalue/DefaultMapEntry.java b/src/org/apache/commons/collections/keyvalue/DefaultMapEntry.java new file mode 100644 index 000000000..e9b23409d --- /dev/null +++ b/src/org/apache/commons/collections/keyvalue/DefaultMapEntry.java @@ -0,0 +1,67 @@ +/* + * 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. + */ +package org.apache.commons.collections.keyvalue; + +import java.util.Map; + +import org.apache.commons.collections.KeyValue; + +/** + * A restricted implementation of {@link java.util.Map.Entry} that prevents + * the Map.Entry contract from being broken. + * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author James Strachan + * @author Michael A. Smith + * @author Neil O'Toole + * @author Stephen Colebourne + */ +public final class DefaultMapEntry extends AbstractMapEntry { + + /** + * Constructs a new entry with the specified key and given value. + * + * @param key the key for the entry, may be null + * @param value the value for the entry, may be null + */ + public DefaultMapEntry(final Object key, final Object value) { + super(key, value); + } + + /** + * Constructs a new entry from the specified KeyValue. + * + * @param pair the pair to copy, must not be null + * @throws NullPointerException if the entry is null + */ + public DefaultMapEntry(final KeyValue pair) { + super(pair.getKey(), pair.getValue()); + } + + /** + * Constructs a new entry from the specified Map.Entry. + * + * @param entry the entry to copy, must not be null + * @throws NullPointerException if the entry is null + */ + public DefaultMapEntry(final Map.Entry entry) { + super(entry.getKey(), entry.getValue()); + } + +} diff --git a/src/org/apache/commons/collections/map/AbstractHashedMap.java b/src/org/apache/commons/collections/map/AbstractHashedMap.java new file mode 100644 index 000000000..2f83dd296 --- /dev/null +++ b/src/org/apache/commons/collections/map/AbstractHashedMap.java @@ -0,0 +1,1329 @@ +/* + * 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. + */ +package org.apache.commons.collections.map; + +import java.io.IOException; +import java.io.ObjectInputStream; +import java.io.ObjectOutputStream; +import java.util.AbstractCollection; +import java.util.AbstractMap; +import java.util.AbstractSet; +import java.util.Collection; +import java.util.ConcurrentModificationException; +import java.util.Iterator; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.Set; + +import org.apache.commons.collections.IterableMap; +import org.apache.commons.collections.KeyValue; +import org.apache.commons.collections.MapIterator; +import org.apache.commons.collections.iterators.EmptyIterator; +import org.apache.commons.collections.iterators.EmptyMapIterator; + +/** + * An abstract implementation of a hash-based map which provides numerous points for + * subclasses to override. + *

+ * This class implements all the features necessary for a subclass hash-based map. + * Key-value entries are stored in instances of the HashEntry class, + * which can be overridden and replaced. The iterators can similarly be replaced, + * without the need to replace the KeySet, EntrySet and Values view classes. + *

+ * Overridable methods are provided to change the default hashing behaviour, and + * to change how entries are added to and removed from the map. Hopefully, all you + * need for unusual subclasses is here. + *

+ * NOTE: From Commons Collections 3.1 this class extends AbstractMap. + * This is to provide backwards compatibility for ReferenceMap between v3.0 and v3.1. + * This extends clause will be removed in v4.0. + * + * @since Commons Collections 3.0 + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author java util HashMap + * @author Stephen Colebourne + * @author Christian Siefkes + */ +public class AbstractHashedMap extends AbstractMap implements IterableMap { + + protected static final String NO_NEXT_ENTRY = "No next() entry in the iteration"; + protected static final String NO_PREVIOUS_ENTRY = "No previous() entry in the iteration"; + protected static final String REMOVE_INVALID = "remove() can only be called once after next()"; + protected static final String GETKEY_INVALID = "getKey() can only be called after next() and before remove()"; + protected static final String GETVALUE_INVALID = "getValue() can only be called after next() and before remove()"; + protected static final String SETVALUE_INVALID = "setValue() can only be called after next() and before remove()"; + + /** The default capacity to use */ + protected static final int DEFAULT_CAPACITY = 16; + /** The default threshold to use */ + protected static final int DEFAULT_THRESHOLD = 12; + /** The default load factor to use */ + protected static final float DEFAULT_LOAD_FACTOR = 0.75f; + /** The maximum capacity allowed */ + protected static final int MAXIMUM_CAPACITY = 1 << 30; + /** An object for masking null */ + protected static final Object NULL = new Object(); + + /** Load factor, normally 0.75 */ + protected transient float loadFactor; + /** The size of the map */ + protected transient int size; + /** Map entries */ + protected transient HashEntry[] data; + /** Size at which to rehash */ + protected transient int threshold; + /** Modification count for iterators */ + protected transient int modCount; + /** Entry set */ + protected transient EntrySet entrySet; + /** Key set */ + protected transient KeySet keySet; + /** Values */ + protected transient Values values; + + /** + * Constructor only used in deserialization, do not use otherwise. + */ + protected AbstractHashedMap() { + super(); + } + + /** + * Constructor which performs no validation on the passed in parameters. + * + * @param initialCapacity the initial capacity, must be a power of two + * @param loadFactor the load factor, must be > 0.0f and generally < 1.0f + * @param threshold the threshold, must be sensible + */ + protected AbstractHashedMap(int initialCapacity, float loadFactor, int threshold) { + super(); + this.loadFactor = loadFactor; + this.data = new HashEntry[initialCapacity]; + this.threshold = threshold; + init(); + } + + /** + * Constructs a new, empty map with the specified initial capacity and + * default load factor. + * + * @param initialCapacity the initial capacity + * @throws IllegalArgumentException if the initial capacity is less than one + */ + protected AbstractHashedMap(int initialCapacity) { + this(initialCapacity, DEFAULT_LOAD_FACTOR); + } + + /** + * Constructs a new, empty map with the specified initial capacity and + * load factor. + * + * @param initialCapacity the initial capacity + * @param loadFactor the load factor + * @throws IllegalArgumentException if the initial capacity is less than one + * @throws IllegalArgumentException if the load factor is less than or equal to zero + */ + protected AbstractHashedMap(int initialCapacity, float loadFactor) { + super(); + if (initialCapacity < 1) { + throw new IllegalArgumentException("Initial capacity must be greater than 0"); + } + if (loadFactor <= 0.0f || Float.isNaN(loadFactor)) { + throw new IllegalArgumentException("Load factor must be greater than 0"); + } + this.loadFactor = loadFactor; + initialCapacity = calculateNewCapacity(initialCapacity); + this.threshold = calculateThreshold(initialCapacity, loadFactor); + this.data = new HashEntry[initialCapacity]; + init(); + } + + /** + * Constructor copying elements from another map. + * + * @param map the map to copy + * @throws NullPointerException if the map is null + */ + protected AbstractHashedMap(Map map) { + this(Math.max(2 * map.size(), DEFAULT_CAPACITY), DEFAULT_LOAD_FACTOR); + putAll(map); + } + + /** + * Initialise subclasses during construction, cloning or deserialization. + */ + protected void init() { + } + + //----------------------------------------------------------------------- + /** + * Gets the value mapped to the key specified. + * + * @param key the key + * @return the mapped value, null if no match + */ + public Object get(Object key) { + key = convertKey(key); + int hashCode = hash(key); + HashEntry entry = data[hashIndex(hashCode, data.length)]; // no local for hash index + while (entry != null) { + if (entry.hashCode == hashCode && isEqualKey(key, entry.key)) { + return entry.getValue(); + } + entry = entry.next; + } + return null; + } + + /** + * Gets the size of the map. + * + * @return the size + */ + public int size() { + return size; + } + + /** + * Checks whether the map is currently empty. + * + * @return true if the map is currently size zero + */ + public boolean isEmpty() { + return (size == 0); + } + + //----------------------------------------------------------------------- + /** + * Checks whether the map contains the specified key. + * + * @param key the key to search for + * @return true if the map contains the key + */ + public boolean containsKey(Object key) { + key = convertKey(key); + int hashCode = hash(key); + HashEntry entry = data[hashIndex(hashCode, data.length)]; // no local for hash index + while (entry != null) { + if (entry.hashCode == hashCode && isEqualKey(key, entry.key)) { + return true; + } + entry = entry.next; + } + return false; + } + + /** + * Checks whether the map contains the specified value. + * + * @param value the value to search for + * @return true if the map contains the value + */ + public boolean containsValue(Object value) { + if (value == null) { + for (int i = 0, isize = data.length; i < isize; i++) { + HashEntry entry = data[i]; + while (entry != null) { + if (entry.getValue() == null) { + return true; + } + entry = entry.next; + } + } + } else { + for (int i = 0, isize = data.length; i < isize; i++) { + HashEntry entry = data[i]; + while (entry != null) { + if (isEqualValue(value, entry.getValue())) { + return true; + } + entry = entry.next; + } + } + } + return false; + } + + //----------------------------------------------------------------------- + /** + * Puts a key-value mapping into this map. + * + * @param key the key to add + * @param value the value to add + * @return the value previously mapped to this key, null if none + */ + public Object put(Object key, Object value) { + key = convertKey(key); + int hashCode = hash(key); + int index = hashIndex(hashCode, data.length); + HashEntry entry = data[index]; + while (entry != null) { + if (entry.hashCode == hashCode && isEqualKey(key, entry.key)) { + Object oldValue = entry.getValue(); + updateEntry(entry, value); + return oldValue; + } + entry = entry.next; + } + + addMapping(index, hashCode, key, value); + return null; + } + + /** + * Puts all the values from the specified map into this map. + *

+ * This implementation iterates around the specified map and + * uses {@link #put(Object, Object)}. + * + * @param map the map to add + * @throws NullPointerException if the map is null + */ + public void putAll(Map map) { + int mapSize = map.size(); + if (mapSize == 0) { + return; + } + int newSize = (int) ((size + mapSize) / loadFactor + 1); + ensureCapacity(calculateNewCapacity(newSize)); + for (Iterator it = map.entrySet().iterator(); it.hasNext();) { + Map.Entry entry = (Map.Entry) it.next(); + put(entry.getKey(), entry.getValue()); + } + } + + /** + * Removes the specified mapping from this map. + * + * @param key the mapping to remove + * @return the value mapped to the removed key, null if key not in map + */ + public Object remove(Object key) { + key = convertKey(key); + int hashCode = hash(key); + int index = hashIndex(hashCode, data.length); + HashEntry entry = data[index]; + HashEntry previous = null; + while (entry != null) { + if (entry.hashCode == hashCode && isEqualKey(key, entry.key)) { + Object oldValue = entry.getValue(); + removeMapping(entry, index, previous); + return oldValue; + } + previous = entry; + entry = entry.next; + } + return null; + } + + /** + * Clears the map, resetting the size to zero and nullifying references + * to avoid garbage collection issues. + */ + public void clear() { + modCount++; + HashEntry[] data = this.data; + for (int i = data.length - 1; i >= 0; i--) { + data[i] = null; + } + size = 0; + } + + //----------------------------------------------------------------------- + /** + * Converts input keys to another object for storage in the map. + * This implementation masks nulls. + * Subclasses can override this to perform alternate key conversions. + *

+ * The reverse conversion can be changed, if required, by overriding the + * getKey() method in the hash entry. + * + * @param key the key convert + * @return the converted key + */ + protected Object convertKey(Object key) { + return (key == null ? NULL : key); + } + + /** + * Gets the hash code for the key specified. + * This implementation uses the additional hashing routine from JDK1.4. + * Subclasses can override this to return alternate hash codes. + * + * @param key the key to get a hash code for + * @return the hash code + */ + protected int hash(Object key) { + // same as JDK 1.4 + int h = key.hashCode(); + h += ~(h << 9); + h ^= (h >>> 14); + h += (h << 4); + h ^= (h >>> 10); + return h; + } + + /** + * Compares two keys, in internal converted form, to see if they are equal. + * This implementation uses the equals method and assumes neither key is null. + * Subclasses can override this to match differently. + * + * @param key1 the first key to compare passed in from outside + * @param key2 the second key extracted from the entry via entry.key + * @return true if equal + */ + protected boolean isEqualKey(Object key1, Object key2) { + return (key1 == key2 || key1.equals(key2)); + } + + /** + * Compares two values, in external form, to see if they are equal. + * This implementation uses the equals method and assumes neither value is null. + * Subclasses can override this to match differently. + * + * @param value1 the first value to compare passed in from outside + * @param value2 the second value extracted from the entry via getValue() + * @return true if equal + */ + protected boolean isEqualValue(Object value1, Object value2) { + return (value1 == value2 || value1.equals(value2)); + } + + /** + * Gets the index into the data storage for the hashCode specified. + * This implementation uses the least significant bits of the hashCode. + * Subclasses can override this to return alternate bucketing. + * + * @param hashCode the hash code to use + * @param dataSize the size of the data to pick a bucket from + * @return the bucket index + */ + protected int hashIndex(int hashCode, int dataSize) { + return hashCode & (dataSize - 1); + } + + //----------------------------------------------------------------------- + /** + * Gets the entry mapped to the key specified. + *

+ * This method exists for subclasses that may need to perform a multi-step + * process accessing the entry. The public methods in this class don't use this + * method to gain a small performance boost. + * + * @param key the key + * @return the entry, null if no match + */ + protected HashEntry getEntry(Object key) { + key = convertKey(key); + int hashCode = hash(key); + HashEntry entry = data[hashIndex(hashCode, data.length)]; // no local for hash index + while (entry != null) { + if (entry.hashCode == hashCode && isEqualKey(key, entry.key)) { + return entry; + } + entry = entry.next; + } + return null; + } + + //----------------------------------------------------------------------- + /** + * Updates an existing key-value mapping to change the value. + *

+ * This implementation calls setValue() on the entry. + * Subclasses could override to handle changes to the map. + * + * @param entry the entry to update + * @param newValue the new value to store + */ + protected void updateEntry(HashEntry entry, Object newValue) { + entry.setValue(newValue); + } + + /** + * Reuses an existing key-value mapping, storing completely new data. + *

+ * This implementation sets all the data fields on the entry. + * Subclasses could populate additional entry fields. + * + * @param entry the entry to update, not null + * @param hashIndex the index in the data array + * @param hashCode the hash code of the key to add + * @param key the key to add + * @param value the value to add + */ + protected void reuseEntry(HashEntry entry, int hashIndex, int hashCode, Object key, Object value) { + entry.next = data[hashIndex]; + entry.hashCode = hashCode; + entry.key = key; + entry.value = value; + } + + //----------------------------------------------------------------------- + /** + * Adds a new key-value mapping into this map. + *

+ * This implementation calls createEntry(), addEntry() + * and checkCapacity(). + * It also handles changes to modCount and size. + * Subclasses could override to fully control adds to the map. + * + * @param hashIndex the index into the data array to store at + * @param hashCode the hash code of the key to add + * @param key the key to add + * @param value the value to add + */ + protected void addMapping(int hashIndex, int hashCode, Object key, Object value) { + modCount++; + HashEntry entry = createEntry(data[hashIndex], hashCode, key, value); + addEntry(entry, hashIndex); + size++; + checkCapacity(); + } + + /** + * Creates an entry to store the key-value data. + *

+ * This implementation creates a new HashEntry instance. + * Subclasses can override this to return a different storage class, + * or implement caching. + * + * @param next the next entry in sequence + * @param hashCode the hash code to use + * @param key the key to store + * @param value the value to store + * @return the newly created entry + */ + protected HashEntry createEntry(HashEntry next, int hashCode, Object key, Object value) { + return new HashEntry(next, hashCode, key, value); + } + + /** + * Adds an entry into this map. + *

+ * This implementation adds the entry to the data storage table. + * Subclasses could override to handle changes to the map. + * + * @param entry the entry to add + * @param hashIndex the index into the data array to store at + */ + protected void addEntry(HashEntry entry, int hashIndex) { + data[hashIndex] = entry; + } + + //----------------------------------------------------------------------- + /** + * Removes a mapping from the map. + *

+ * This implementation calls removeEntry() and destroyEntry(). + * It also handles changes to modCount and size. + * Subclasses could override to fully control removals from the map. + * + * @param entry the entry to remove + * @param hashIndex the index into the data structure + * @param previous the previous entry in the chain + */ + protected void removeMapping(HashEntry entry, int hashIndex, HashEntry previous) { + modCount++; + removeEntry(entry, hashIndex, previous); + size--; + destroyEntry(entry); + } + + /** + * Removes an entry from the chain stored in a particular index. + *

+ * This implementation removes the entry from the data storage table. + * The size is not updated. + * Subclasses could override to handle changes to the map. + * + * @param entry the entry to remove + * @param hashIndex the index into the data structure + * @param previous the previous entry in the chain + */ + protected void removeEntry(HashEntry entry, int hashIndex, HashEntry previous) { + if (previous == null) { + data[hashIndex] = entry.next; + } else { + previous.next = entry.next; + } + } + + /** + * Kills an entry ready for the garbage collector. + *

+ * This implementation prepares the HashEntry for garbage collection. + * Subclasses can override this to implement caching (override clear as well). + * + * @param entry the entry to destroy + */ + protected void destroyEntry(HashEntry entry) { + entry.next = null; + entry.key = null; + entry.value = null; + } + + //----------------------------------------------------------------------- + /** + * Checks the capacity of the map and enlarges it if necessary. + *

+ * This implementation uses the threshold to check if the map needs enlarging + */ + protected void checkCapacity() { + if (size >= threshold) { + int newCapacity = data.length * 2; + if (newCapacity <= MAXIMUM_CAPACITY) { + ensureCapacity(newCapacity); + } + } + } + + /** + * Changes the size of the data structure to the capacity proposed. + * + * @param newCapacity the new capacity of the array (a power of two, less or equal to max) + */ + protected void ensureCapacity(int newCapacity) { + int oldCapacity = data.length; + if (newCapacity <= oldCapacity) { + return; + } + if (size == 0) { + threshold = calculateThreshold(newCapacity, loadFactor); + data = new HashEntry[newCapacity]; + } else { + HashEntry oldEntries[] = data; + HashEntry newEntries[] = new HashEntry[newCapacity]; + + modCount++; + for (int i = oldCapacity - 1; i >= 0; i--) { + HashEntry entry = oldEntries[i]; + if (entry != null) { + oldEntries[i] = null; // gc + do { + HashEntry next = entry.next; + int index = hashIndex(entry.hashCode, newCapacity); + entry.next = newEntries[index]; + newEntries[index] = entry; + entry = next; + } while (entry != null); + } + } + threshold = calculateThreshold(newCapacity, loadFactor); + data = newEntries; + } + } + + /** + * Calculates the new capacity of the map. + * This implementation normalizes the capacity to a power of two. + * + * @param proposedCapacity the proposed capacity + * @return the normalized new capacity + */ + protected int calculateNewCapacity(int proposedCapacity) { + int newCapacity = 1; + if (proposedCapacity > MAXIMUM_CAPACITY) { + newCapacity = MAXIMUM_CAPACITY; + } else { + while (newCapacity < proposedCapacity) { + newCapacity <<= 1; // multiply by two + } + if (newCapacity > MAXIMUM_CAPACITY) { + newCapacity = MAXIMUM_CAPACITY; + } + } + return newCapacity; + } + + /** + * Calculates the new threshold of the map, where it will be resized. + * This implementation uses the load factor. + * + * @param newCapacity the new capacity + * @param factor the load factor + * @return the new resize threshold + */ + protected int calculateThreshold(int newCapacity, float factor) { + return (int) (newCapacity * factor); + } + + //----------------------------------------------------------------------- + /** + * Gets the next field from a HashEntry. + * Used in subclasses that have no visibility of the field. + * + * @param entry the entry to query, must not be null + * @return the next field of the entry + * @throws NullPointerException if the entry is null + * @since Commons Collections 3.1 + */ + protected HashEntry entryNext(HashEntry entry) { + return entry.next; + } + + /** + * Gets the hashCode field from a HashEntry. + * Used in subclasses that have no visibility of the field. + * + * @param entry the entry to query, must not be null + * @return the hashCode field of the entry + * @throws NullPointerException if the entry is null + * @since Commons Collections 3.1 + */ + protected int entryHashCode(HashEntry entry) { + return entry.hashCode; + } + + /** + * Gets the key field from a HashEntry. + * Used in subclasses that have no visibility of the field. + * + * @param entry the entry to query, must not be null + * @return the key field of the entry + * @throws NullPointerException if the entry is null + * @since Commons Collections 3.1 + */ + protected Object entryKey(HashEntry entry) { + return entry.key; + } + + /** + * Gets the value field from a HashEntry. + * Used in subclasses that have no visibility of the field. + * + * @param entry the entry to query, must not be null + * @return the value field of the entry + * @throws NullPointerException if the entry is null + * @since Commons Collections 3.1 + */ + protected Object entryValue(HashEntry entry) { + return entry.value; + } + + //----------------------------------------------------------------------- + /** + * Gets an iterator over the map. + * Changes made to the iterator affect this map. + *

+ * A MapIterator returns the keys in the map. It also provides convenient + * methods to get the key and value, and set the value. + * It avoids the need to create an entrySet/keySet/values object. + * It also avoids creating the Map.Entry object. + * + * @return the map iterator + */ + public MapIterator mapIterator() { + if (size == 0) { + return EmptyMapIterator.INSTANCE; + } + return new HashMapIterator(this); + } + + /** + * MapIterator implementation. + */ + protected static class HashMapIterator extends HashIterator implements MapIterator { + + protected HashMapIterator(AbstractHashedMap parent) { + super(parent); + } + + public Object next() { + return super.nextEntry().getKey(); + } + + public Object getKey() { + HashEntry current = currentEntry(); + if (current == null) { + throw new IllegalStateException(AbstractHashedMap.GETKEY_INVALID); + } + return current.getKey(); + } + + public Object getValue() { + HashEntry current = currentEntry(); + if (current == null) { + throw new IllegalStateException(AbstractHashedMap.GETVALUE_INVALID); + } + return current.getValue(); + } + + public Object setValue(Object value) { + HashEntry current = currentEntry(); + if (current == null) { + throw new IllegalStateException(AbstractHashedMap.SETVALUE_INVALID); + } + return current.setValue(value); + } + } + + //----------------------------------------------------------------------- + /** + * Gets the entrySet view of the map. + * Changes made to the view affect this map. + * To simply iterate through the entries, use {@link #mapIterator()}. + * + * @return the entrySet view + */ + public Set entrySet() { + if (entrySet == null) { + entrySet = new EntrySet(this); + } + return entrySet; + } + + /** + * Creates an entry set iterator. + * Subclasses can override this to return iterators with different properties. + * + * @return the entrySet iterator + */ + protected Iterator createEntrySetIterator() { + if (size() == 0) { + return EmptyIterator.INSTANCE; + } + return new EntrySetIterator(this); + } + + /** + * EntrySet implementation. + */ + protected static class EntrySet extends AbstractSet { + /** The parent map */ + protected final AbstractHashedMap parent; + + protected EntrySet(AbstractHashedMap parent) { + super(); + this.parent = parent; + } + + public int size() { + return parent.size(); + } + + public void clear() { + parent.clear(); + } + + public boolean contains(Object entry) { + if (entry instanceof Map.Entry) { + Map.Entry e = (Map.Entry) entry; + Entry match = parent.getEntry(e.getKey()); + return (match != null && match.equals(e)); + } + return false; + } + + public boolean remove(Object obj) { + if (obj instanceof Map.Entry == false) { + return false; + } + if (contains(obj) == false) { + return false; + } + Map.Entry entry = (Map.Entry) obj; + Object key = entry.getKey(); + parent.remove(key); + return true; + } + + public Iterator iterator() { + return parent.createEntrySetIterator(); + } + } + + /** + * EntrySet iterator. + */ + protected static class EntrySetIterator extends HashIterator { + + protected EntrySetIterator(AbstractHashedMap parent) { + super(parent); + } + + public Object next() { + return super.nextEntry(); + } + } + + //----------------------------------------------------------------------- + /** + * Gets the keySet view of the map. + * Changes made to the view affect this map. + * To simply iterate through the keys, use {@link #mapIterator()}. + * + * @return the keySet view + */ + public Set keySet() { + if (keySet == null) { + keySet = new KeySet(this); + } + return keySet; + } + + /** + * Creates a key set iterator. + * Subclasses can override this to return iterators with different properties. + * + * @return the keySet iterator + */ + protected Iterator createKeySetIterator() { + if (size() == 0) { + return EmptyIterator.INSTANCE; + } + return new KeySetIterator(this); + } + + /** + * KeySet implementation. + */ + protected static class KeySet extends AbstractSet { + /** The parent map */ + protected final AbstractHashedMap parent; + + protected KeySet(AbstractHashedMap parent) { + super(); + this.parent = parent; + } + + public int size() { + return parent.size(); + } + + public void clear() { + parent.clear(); + } + + public boolean contains(Object key) { + return parent.containsKey(key); + } + + public boolean remove(Object key) { + boolean result = parent.containsKey(key); + parent.remove(key); + return result; + } + + public Iterator iterator() { + return parent.createKeySetIterator(); + } + } + + /** + * KeySet iterator. + */ + protected static class KeySetIterator extends EntrySetIterator { + + protected KeySetIterator(AbstractHashedMap parent) { + super(parent); + } + + public Object next() { + return super.nextEntry().getKey(); + } + } + + //----------------------------------------------------------------------- + /** + * Gets the values view of the map. + * Changes made to the view affect this map. + * To simply iterate through the values, use {@link #mapIterator()}. + * + * @return the values view + */ + public Collection values() { + if (values == null) { + values = new Values(this); + } + return values; + } + + /** + * Creates a values iterator. + * Subclasses can override this to return iterators with different properties. + * + * @return the values iterator + */ + protected Iterator createValuesIterator() { + if (size() == 0) { + return EmptyIterator.INSTANCE; + } + return new ValuesIterator(this); + } + + /** + * Values implementation. + */ + protected static class Values extends AbstractCollection { + /** The parent map */ + protected final AbstractHashedMap parent; + + protected Values(AbstractHashedMap parent) { + super(); + this.parent = parent; + } + + public int size() { + return parent.size(); + } + + public void clear() { + parent.clear(); + } + + public boolean contains(Object value) { + return parent.containsValue(value); + } + + public Iterator iterator() { + return parent.createValuesIterator(); + } + } + + /** + * Values iterator. + */ + protected static class ValuesIterator extends HashIterator { + + protected ValuesIterator(AbstractHashedMap parent) { + super(parent); + } + + public Object next() { + return super.nextEntry().getValue(); + } + } + + //----------------------------------------------------------------------- + /** + * HashEntry used to store the data. + *

+ * If you subclass AbstractHashedMap but not HashEntry + * then you will not be able to access the protected fields. + * The entryXxx() methods on AbstractHashedMap exist + * to provide the necessary access. + */ + protected static class HashEntry implements Map.Entry, KeyValue { + /** The next entry in the hash chain */ + protected HashEntry next; + /** The hash code of the key */ + protected int hashCode; + /** The key */ + protected Object key; + /** The value */ + protected Object value; + + protected HashEntry(HashEntry next, int hashCode, Object key, Object value) { + super(); + this.next = next; + this.hashCode = hashCode; + this.key = key; + this.value = value; + } + + public Object getKey() { + return (key == NULL ? null : key); + } + + public Object getValue() { + return value; + } + + public Object setValue(Object value) { + Object old = this.value; + this.value = value; + return old; + } + + public boolean equals(Object obj) { + if (obj == this) { + return true; + } + if (obj instanceof Map.Entry == false) { + return false; + } + Map.Entry other = (Map.Entry) obj; + return + (getKey() == null ? other.getKey() == null : getKey().equals(other.getKey())) && + (getValue() == null ? other.getValue() == null : getValue().equals(other.getValue())); + } + + public int hashCode() { + return (getKey() == null ? 0 : getKey().hashCode()) ^ + (getValue() == null ? 0 : getValue().hashCode()); + } + + public String toString() { + return new StringBuffer().append(getKey()).append('=').append(getValue()).toString(); + } + } + + /** + * Base Iterator + */ + protected static abstract class HashIterator implements Iterator { + + /** The parent map */ + protected final AbstractHashedMap parent; + /** The current index into the array of buckets */ + protected int hashIndex; + /** The last returned entry */ + protected HashEntry last; + /** The next entry */ + protected HashEntry next; + /** The modification count expected */ + protected int expectedModCount; + + protected HashIterator(AbstractHashedMap parent) { + super(); + this.parent = parent; + HashEntry[] data = parent.data; + int i = data.length; + HashEntry next = null; + while (i > 0 && next == null) { + next = data[--i]; + } + this.next = next; + this.hashIndex = i; + this.expectedModCount = parent.modCount; + } + + public boolean hasNext() { + return (next != null); + } + + protected HashEntry nextEntry() { + if (parent.modCount != expectedModCount) { + throw new ConcurrentModificationException(); + } + HashEntry newCurrent = next; + if (newCurrent == null) { + throw new NoSuchElementException(AbstractHashedMap.NO_NEXT_ENTRY); + } + HashEntry[] data = parent.data; + int i = hashIndex; + HashEntry n = newCurrent.next; + while (n == null && i > 0) { + n = data[--i]; + } + next = n; + hashIndex = i; + last = newCurrent; + return newCurrent; + } + + protected HashEntry currentEntry() { + return last; + } + + public void remove() { + if (last == null) { + throw new IllegalStateException(AbstractHashedMap.REMOVE_INVALID); + } + if (parent.modCount != expectedModCount) { + throw new ConcurrentModificationException(); + } + parent.remove(last.getKey()); + last = null; + expectedModCount = parent.modCount; + } + + public String toString() { + if (last != null) { + return "Iterator[" + last.getKey() + "=" + last.getValue() + "]"; + } else { + return "Iterator[]"; + } + } + } + + //----------------------------------------------------------------------- + /** + * Writes the map data to the stream. This method must be overridden if a + * subclass must be setup before put() is used. + *

+ * Serialization is not one of the JDK's nicest topics. Normal serialization will + * initialise the superclass before the subclass. Sometimes however, this isn't + * what you want, as in this case the put() method on read can be + * affected by subclass state. + *

+ * The solution adopted here is to serialize the state data of this class in + * this protected method. This method must be called by the + * writeObject() of the first serializable subclass. + *

+ * Subclasses may override if they have a specific field that must be present + * on read before this implementation will work. Generally, the read determines + * what must be serialized here, if anything. + * + * @param out the output stream + */ + protected void doWriteObject(ObjectOutputStream out) throws IOException { + out.writeFloat(loadFactor); + out.writeInt(data.length); + out.writeInt(size); + for (MapIterator it = mapIterator(); it.hasNext();) { + out.writeObject(it.next()); + out.writeObject(it.getValue()); + } + } + + /** + * Reads the map data from the stream. This method must be overridden if a + * subclass must be setup before put() is used. + *

+ * Serialization is not one of the JDK's nicest topics. Normal serialization will + * initialise the superclass before the subclass. Sometimes however, this isn't + * what you want, as in this case the put() method on read can be + * affected by subclass state. + *

+ * The solution adopted here is to deserialize the state data of this class in + * this protected method. This method must be called by the + * readObject() of the first serializable subclass. + *

+ * Subclasses may override if the subclass has a specific field that must be present + * before put() or calculateThreshold() will work correctly. + * + * @param in the input stream + */ + protected void doReadObject(ObjectInputStream in) throws IOException, ClassNotFoundException { + loadFactor = in.readFloat(); + int capacity = in.readInt(); + int size = in.readInt(); + init(); + threshold = calculateThreshold(capacity, loadFactor); + data = new HashEntry[capacity]; + for (int i = 0; i < size; i++) { + Object key = in.readObject(); + Object value = in.readObject(); + put(key, value); + } + } + + //----------------------------------------------------------------------- + /** + * Clones the map without cloning the keys or values. + *

+ * To implement clone(), a subclass must implement the + * Cloneable interface and make this method public. + * + * @return a shallow clone + */ + protected Object clone() { + try { + AbstractHashedMap cloned = (AbstractHashedMap) super.clone(); + cloned.data = new HashEntry[data.length]; + cloned.entrySet = null; + cloned.keySet = null; + cloned.values = null; + cloned.modCount = 0; + cloned.size = 0; + cloned.init(); + cloned.putAll(this); + return cloned; + + } catch (CloneNotSupportedException ex) { + return null; // should never happen + } + } + + /** + * Compares this map with another. + * + * @param obj the object to compare to + * @return true if equal + */ + public boolean equals(Object obj) { + if (obj == this) { + return true; + } + if (obj instanceof Map == false) { + return false; + } + Map map = (Map) obj; + if (map.size() != size()) { + return false; + } + MapIterator it = mapIterator(); + try { + while (it.hasNext()) { + Object key = it.next(); + Object value = it.getValue(); + if (value == null) { + if (map.get(key) != null || map.containsKey(key) == false) { + return false; + } + } else { + if (value.equals(map.get(key)) == false) { + return false; + } + } + } + } catch (ClassCastException ignored) { + return false; + } catch (NullPointerException ignored) { + return false; + } + return true; + } + + /** + * Gets the standard Map hashCode. + * + * @return the hash code defined in the Map interface + */ + public int hashCode() { + int total = 0; + Iterator it = createEntrySetIterator(); + while (it.hasNext()) { + total += it.next().hashCode(); + } + return total; + } + + /** + * Gets the map as a String. + * + * @return a string version of the map + */ + public String toString() { + if (size() == 0) { + return "{}"; + } + StringBuffer buf = new StringBuffer(32 * size()); + buf.append('{'); + + MapIterator it = mapIterator(); + boolean hasNext = it.hasNext(); + while (hasNext) { + Object key = it.next(); + Object value = it.getValue(); + buf.append(key == this ? "(this Map)" : key) + .append('=') + .append(value == this ? "(this Map)" : value); + + hasNext = it.hasNext(); + if (hasNext) { + buf.append(',').append(' '); + } + } + + buf.append('}'); + return buf.toString(); + } +} diff --git a/src/org/apache/commons/collections/map/AbstractReferenceMap.java b/src/org/apache/commons/collections/map/AbstractReferenceMap.java new file mode 100644 index 000000000..e6b735440 --- /dev/null +++ b/src/org/apache/commons/collections/map/AbstractReferenceMap.java @@ -0,0 +1,981 @@ +/* + * 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. + */ +package org.apache.commons.collections.map; + +import java.io.IOException; +import java.io.ObjectInputStream; +import java.io.ObjectOutputStream; +import java.lang.ref.Reference; +import java.lang.ref.ReferenceQueue; +import java.lang.ref.SoftReference; +import java.lang.ref.WeakReference; +import java.util.ArrayList; +import java.util.Collection; +import java.util.ConcurrentModificationException; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.Set; + +import org.apache.commons.collections.MapIterator; +import org.apache.commons.collections.keyvalue.DefaultMapEntry; + +/** + * An abstract implementation of a hash-based map that allows the entries to + * be removed by the garbage collector. + *

+ * This class implements all the features necessary for a subclass reference + * hash-based map. Key-value entries are stored in instances of the + * ReferenceEntry class which can be overridden and replaced. + * The iterators can similarly be replaced, without the need to replace the KeySet, + * EntrySet and Values view classes. + *

+ * Overridable methods are provided to change the default hashing behaviour, and + * to change how entries are added to and removed from the map. Hopefully, all you + * need for unusual subclasses is here. + *

+ * When you construct an AbstractReferenceMap, you can specify what + * kind of references are used to store the map's keys and values. + * If non-hard references are used, then the garbage collector can remove + * mappings if a key or value becomes unreachable, or if the JVM's memory is + * running low. For information on how the different reference types behave, + * see {@link Reference}. + *

+ * Different types of references can be specified for keys and values. + * The keys can be configured to be weak but the values hard, + * in which case this class will behave like a + * + * WeakHashMap. However, you can also specify hard keys and + * weak values, or any other combination. The default constructor uses + * hard keys and soft values, providing a memory-sensitive cache. + *

+ * This {@link Map} implementation does not allow null elements. + * Attempting to add a null key or value to the map will raise a + * NullPointerException. + *

+ * All the available iterators can be reset back to the start by casting to + * ResettableIterator and calling reset(). + *

+ * This implementation is not synchronized. + * You can use {@link java.util.Collections#synchronizedMap} to + * provide synchronized access to a ReferenceMap. + * + * @see java.lang.ref.Reference + * @since Commons Collections 3.1 (extracted from ReferenceMap in 3.0) + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Paul Jack + * @author Stephen Colebourne + */ +public abstract class AbstractReferenceMap extends AbstractHashedMap { + + /** Constant indicating that hard references should be used */ + public static final int HARD = 0; + + /** Constant indicating that soft references should be used */ + public static final int SOFT = 1; + + /** Constant indicating that weak references should be used */ + public static final int WEAK = 2; + + /** + * The reference type for keys. Must be HARD, SOFT, WEAK. + * @serial + */ + protected int keyType; + + /** + * The reference type for values. Must be HARD, SOFT, WEAK. + * @serial + */ + protected int valueType; + + /** + * Should the value be automatically purged when the associated key has been collected? + */ + protected boolean purgeValues; + + /** + * ReferenceQueue used to eliminate stale mappings. + * See purge. + */ + private transient ReferenceQueue queue; + + //----------------------------------------------------------------------- + /** + * Constructor used during deserialization. + */ + protected AbstractReferenceMap() { + super(); + } + + /** + * Constructs a new empty map with the specified reference types, + * load factor and initial capacity. + * + * @param keyType the type of reference to use for keys; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param valueType the type of reference to use for values; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param capacity the initial capacity for the map + * @param loadFactor the load factor for the map + * @param purgeValues should the value be automatically purged when the + * key is garbage collected + */ + protected AbstractReferenceMap( + int keyType, int valueType, int capacity, + float loadFactor, boolean purgeValues) { + super(capacity, loadFactor); + verify("keyType", keyType); + verify("valueType", valueType); + this.keyType = keyType; + this.valueType = valueType; + this.purgeValues = purgeValues; + } + + /** + * Initialise this subclass during construction, cloning or deserialization. + */ + protected void init() { + queue = new ReferenceQueue(); + } + + //----------------------------------------------------------------------- + /** + * Checks the type int is a valid value. + * + * @param name the name for error messages + * @param type the type value to check + * @throws IllegalArgumentException if the value if invalid + */ + private static void verify(String name, int type) { + if ((type < HARD) || (type > WEAK)) { + throw new IllegalArgumentException(name + " must be HARD, SOFT, WEAK."); + } + } + + //----------------------------------------------------------------------- + /** + * Gets the size of the map. + * + * @return the size + */ + public int size() { + purgeBeforeRead(); + return super.size(); + } + + /** + * Checks whether the map is currently empty. + * + * @return true if the map is currently size zero + */ + public boolean isEmpty() { + purgeBeforeRead(); + return super.isEmpty(); + } + + /** + * Checks whether the map contains the specified key. + * + * @param key the key to search for + * @return true if the map contains the key + */ + public boolean containsKey(Object key) { + purgeBeforeRead(); + Entry entry = getEntry(key); + if (entry == null) { + return false; + } + return (entry.getValue() != null); + } + + /** + * Checks whether the map contains the specified value. + * + * @param value the value to search for + * @return true if the map contains the value + */ + public boolean containsValue(Object value) { + purgeBeforeRead(); + if (value == null) { + return false; + } + return super.containsValue(value); + } + + /** + * Gets the value mapped to the key specified. + * + * @param key the key + * @return the mapped value, null if no match + */ + public Object get(Object key) { + purgeBeforeRead(); + Entry entry = getEntry(key); + if (entry == null) { + return null; + } + return entry.getValue(); + } + + + /** + * Puts a key-value mapping into this map. + * Neither the key nor the value may be null. + * + * @param key the key to add, must not be null + * @param value the value to add, must not be null + * @return the value previously mapped to this key, null if none + * @throws NullPointerException if either the key or value is null + */ + public Object put(Object key, Object value) { + if (key == null) { + throw new NullPointerException("null keys not allowed"); + } + if (value == null) { + throw new NullPointerException("null values not allowed"); + } + + purgeBeforeWrite(); + return super.put(key, value); + } + + /** + * Removes the specified mapping from this map. + * + * @param key the mapping to remove + * @return the value mapped to the removed key, null if key not in map + */ + public Object remove(Object key) { + if (key == null) { + return null; + } + purgeBeforeWrite(); + return super.remove(key); + } + + /** + * Clears this map. + */ + public void clear() { + super.clear(); + while (queue.poll() != null) {} // drain the queue + } + + //----------------------------------------------------------------------- + /** + * Gets a MapIterator over the reference map. + * The iterator only returns valid key/value pairs. + * + * @return a map iterator + */ + public MapIterator mapIterator() { + return new ReferenceMapIterator(this); + } + + /** + * Returns a set view of this map's entries. + * An iterator returned entry is valid until next() is called again. + * The setValue() method on the toArray entries has no effect. + * + * @return a set view of this map's entries + */ + public Set entrySet() { + if (entrySet == null) { + entrySet = new ReferenceEntrySet(this); + } + return entrySet; + } + + /** + * Returns a set view of this map's keys. + * + * @return a set view of this map's keys + */ + public Set keySet() { + if (keySet == null) { + keySet = new ReferenceKeySet(this); + } + return keySet; + } + + /** + * Returns a collection view of this map's values. + * + * @return a set view of this map's values + */ + public Collection values() { + if (values == null) { + values = new ReferenceValues(this); + } + return values; + } + + //----------------------------------------------------------------------- + /** + * Purges stale mappings from this map before read operations. + *

+ * This implementation calls {@link #purge()} to maintain a consistent state. + */ + protected void purgeBeforeRead() { + purge(); + } + + /** + * Purges stale mappings from this map before write operations. + *

+ * This implementation calls {@link #purge()} to maintain a consistent state. + */ + protected void purgeBeforeWrite() { + purge(); + } + + /** + * Purges stale mappings from this map. + *

+ * Note that this method is not synchronized! Special + * care must be taken if, for instance, you want stale + * mappings to be removed on a periodic basis by some + * background thread. + */ + protected void purge() { + Reference ref = queue.poll(); + while (ref != null) { + purge(ref); + ref = queue.poll(); + } + } + + /** + * Purges the specified reference. + * + * @param ref the reference to purge + */ + protected void purge(Reference ref) { + // The hashCode of the reference is the hashCode of the + // mapping key, even if the reference refers to the + // mapping value... + int hash = ref.hashCode(); + int index = hashIndex(hash, data.length); + HashEntry previous = null; + HashEntry entry = data[index]; + while (entry != null) { + if (((ReferenceEntry) entry).purge(ref)) { + if (previous == null) { + data[index] = entry.next; + } else { + previous.next = entry.next; + } + this.size--; + return; + } + previous = entry; + entry = entry.next; + } + + } + + //----------------------------------------------------------------------- + /** + * Gets the entry mapped to the key specified. + * + * @param key the key + * @return the entry, null if no match + */ + protected HashEntry getEntry(Object key) { + if (key == null) { + return null; + } else { + return super.getEntry(key); + } + } + + /** + * Gets the hash code for a MapEntry. + * Subclasses can override this, for example to use the identityHashCode. + * + * @param key the key to get a hash code for, may be null + * @param value the value to get a hash code for, may be null + * @return the hash code, as per the MapEntry specification + */ + protected int hashEntry(Object key, Object value) { + return (key == null ? 0 : key.hashCode()) ^ + (value == null ? 0 : value.hashCode()); + } + + /** + * Compares two keys, in internal converted form, to see if they are equal. + *

+ * This implementation converts the key from the entry to a real reference + * before comparison. + * + * @param key1 the first key to compare passed in from outside + * @param key2 the second key extracted from the entry via entry.key + * @return true if equal + */ + protected boolean isEqualKey(Object key1, Object key2) { + key2 = (keyType > HARD ? ((Reference) key2).get() : key2); + return (key1 == key2 || key1.equals(key2)); + } + + /** + * Creates a ReferenceEntry instead of a HashEntry. + * + * @param next the next entry in sequence + * @param hashCode the hash code to use + * @param key the key to store + * @param value the value to store + * @return the newly created entry + */ + protected HashEntry createEntry(HashEntry next, int hashCode, Object key, Object value) { + return new ReferenceEntry(this, next, hashCode, key, value); + } + + /** + * Creates an entry set iterator. + * + * @return the entrySet iterator + */ + protected Iterator createEntrySetIterator() { + return new ReferenceEntrySetIterator(this); + } + + /** + * Creates an key set iterator. + * + * @return the keySet iterator + */ + protected Iterator createKeySetIterator() { + return new ReferenceKeySetIterator(this); + } + + /** + * Creates an values iterator. + * + * @return the values iterator + */ + protected Iterator createValuesIterator() { + return new ReferenceValuesIterator(this); + } + + //----------------------------------------------------------------------- + /** + * EntrySet implementation. + */ + static class ReferenceEntrySet extends EntrySet { + + protected ReferenceEntrySet(AbstractHashedMap parent) { + super(parent); + } + + public Object[] toArray() { + return toArray(new Object[0]); + } + + public Object[] toArray(Object[] arr) { + // special implementation to handle disappearing entries + ArrayList list = new ArrayList(); + Iterator iterator = iterator(); + while (iterator.hasNext()) { + Entry e = (Entry) iterator.next(); + list.add(new DefaultMapEntry(e.getKey(), e.getValue())); + } + return list.toArray(arr); + } + } + + //----------------------------------------------------------------------- + /** + * KeySet implementation. + */ + static class ReferenceKeySet extends KeySet { + + protected ReferenceKeySet(AbstractHashedMap parent) { + super(parent); + } + + public Object[] toArray() { + return toArray(new Object[0]); + } + + public Object[] toArray(Object[] arr) { + // special implementation to handle disappearing keys + List list = new ArrayList(parent.size()); + for (Iterator it = iterator(); it.hasNext(); ) { + list.add(it.next()); + } + return list.toArray(arr); + } + } + + //----------------------------------------------------------------------- + /** + * Values implementation. + */ + static class ReferenceValues extends Values { + + protected ReferenceValues(AbstractHashedMap parent) { + super(parent); + } + + public Object[] toArray() { + return toArray(new Object[0]); + } + + public Object[] toArray(Object[] arr) { + // special implementation to handle disappearing values + List list = new ArrayList(parent.size()); + for (Iterator it = iterator(); it.hasNext(); ) { + list.add(it.next()); + } + return list.toArray(arr); + } + } + + //----------------------------------------------------------------------- + /** + * A MapEntry implementation for the map. + *

+ * If getKey() or getValue() returns null, it means + * the mapping is stale and should be removed. + * + * @since Commons Collections 3.1 + */ + protected static class ReferenceEntry extends HashEntry { + /** The parent map */ + protected final AbstractReferenceMap parent; + + /** + * Creates a new entry object for the ReferenceMap. + * + * @param parent the parent map + * @param next the next entry in the hash bucket + * @param hashCode the hash code of the key + * @param key the key + * @param value the value + */ + public ReferenceEntry(AbstractReferenceMap parent, HashEntry next, int hashCode, Object key, Object value) { + super(next, hashCode, null, null); + this.parent = parent; + this.key = toReference(parent.keyType, key, hashCode); + this.value = toReference(parent.valueType, value, hashCode); // the key hashCode is passed in deliberately + } + + /** + * Gets the key from the entry. + * This method dereferences weak and soft keys and thus may return null. + * + * @return the key, which may be null if it was garbage collected + */ + public Object getKey() { + return (parent.keyType > HARD) ? ((Reference) key).get() : key; + } + + /** + * Gets the value from the entry. + * This method dereferences weak and soft value and thus may return null. + * + * @return the value, which may be null if it was garbage collected + */ + public Object getValue() { + return (parent.valueType > HARD) ? ((Reference) value).get() : value; + } + + /** + * Sets the value of the entry. + * + * @param obj the object to store + * @return the previous value + */ + public Object setValue(Object obj) { + Object old = getValue(); + if (parent.valueType > HARD) { + ((Reference)value).clear(); + } + value = toReference(parent.valueType, obj, hashCode); + return old; + } + + /** + * Compares this map entry to another. + *

+ * This implementation uses isEqualKey and + * isEqualValue on the main map for comparison. + * + * @param obj the other map entry to compare to + * @return true if equal, false if not + */ + public boolean equals(Object obj) { + if (obj == this) { + return true; + } + if (obj instanceof Map.Entry == false) { + return false; + } + + Map.Entry entry = (Map.Entry)obj; + Object entryKey = entry.getKey(); // convert to hard reference + Object entryValue = entry.getValue(); // convert to hard reference + if ((entryKey == null) || (entryValue == null)) { + return false; + } + // compare using map methods, aiding identity subclass + // note that key is direct access and value is via method + return parent.isEqualKey(entryKey, key) && + parent.isEqualValue(entryValue, getValue()); + } + + /** + * Gets the hashcode of the entry using temporary hard references. + *

+ * This implementation uses hashEntry on the main map. + * + * @return the hashcode of the entry + */ + public int hashCode() { + return parent.hashEntry(getKey(), getValue()); + } + + /** + * Constructs a reference of the given type to the given referent. + * The reference is registered with the queue for later purging. + * + * @param type HARD, SOFT or WEAK + * @param referent the object to refer to + * @param hash the hash code of the key of the mapping; + * this number might be different from referent.hashCode() if + * the referent represents a value and not a key + */ + protected Object toReference(int type, Object referent, int hash) { + switch (type) { + case HARD: return referent; + case SOFT: return new SoftRef(hash, referent, parent.queue); + case WEAK: return new WeakRef(hash, referent, parent.queue); + default: throw new Error(); + } + } + + /** + * Purges the specified reference + * @param ref the reference to purge + * @return true or false + */ + boolean purge(Reference ref) { + boolean r = (parent.keyType > HARD) && (key == ref); + r = r || ((parent.valueType > HARD) && (value == ref)); + if (r) { + if (parent.keyType > HARD) { + ((Reference)key).clear(); + } + if (parent.valueType > HARD) { + ((Reference)value).clear(); + } else if (parent.purgeValues) { + value = null; + } + } + return r; + } + + /** + * Gets the next entry in the bucket. + * + * @return the next entry in the bucket + */ + protected ReferenceEntry next() { + return (ReferenceEntry) next; + } + } + + //----------------------------------------------------------------------- + /** + * The EntrySet iterator. + */ + static class ReferenceEntrySetIterator implements Iterator { + /** The parent map */ + final AbstractReferenceMap parent; + + // These fields keep track of where we are in the table. + int index; + ReferenceEntry entry; + ReferenceEntry previous; + + // These Object fields provide hard references to the + // current and next entry; this assures that if hasNext() + // returns true, next() will actually return a valid element. + Object nextKey, nextValue; + Object currentKey, currentValue; + + int expectedModCount; + + public ReferenceEntrySetIterator(AbstractReferenceMap parent) { + super(); + this.parent = parent; + index = (parent.size() != 0 ? parent.data.length : 0); + // have to do this here! size() invocation above + // may have altered the modCount. + expectedModCount = parent.modCount; + } + + public boolean hasNext() { + checkMod(); + while (nextNull()) { + ReferenceEntry e = entry; + int i = index; + while ((e == null) && (i > 0)) { + i--; + e = (ReferenceEntry) parent.data[i]; + } + entry = e; + index = i; + if (e == null) { + currentKey = null; + currentValue = null; + return false; + } + nextKey = e.getKey(); + nextValue = e.getValue(); + if (nextNull()) { + entry = entry.next(); + } + } + return true; + } + + private void checkMod() { + if (parent.modCount != expectedModCount) { + throw new ConcurrentModificationException(); + } + } + + private boolean nextNull() { + return (nextKey == null) || (nextValue == null); + } + + protected ReferenceEntry nextEntry() { + checkMod(); + if (nextNull() && !hasNext()) { + throw new NoSuchElementException(); + } + previous = entry; + entry = entry.next(); + currentKey = nextKey; + currentValue = nextValue; + nextKey = null; + nextValue = null; + return previous; + } + + protected ReferenceEntry currentEntry() { + checkMod(); + return previous; + } + + public Object next() { + return nextEntry(); + } + + public void remove() { + checkMod(); + if (previous == null) { + throw new IllegalStateException(); + } + parent.remove(currentKey); + previous = null; + currentKey = null; + currentValue = null; + expectedModCount = parent.modCount; + } + } + + /** + * The keySet iterator. + */ + static class ReferenceKeySetIterator extends ReferenceEntrySetIterator { + + ReferenceKeySetIterator(AbstractReferenceMap parent) { + super(parent); + } + + public Object next() { + return nextEntry().getKey(); + } + } + + /** + * The values iterator. + */ + static class ReferenceValuesIterator extends ReferenceEntrySetIterator { + + ReferenceValuesIterator(AbstractReferenceMap parent) { + super(parent); + } + + public Object next() { + return nextEntry().getValue(); + } + } + + /** + * The MapIterator implementation. + */ + static class ReferenceMapIterator extends ReferenceEntrySetIterator implements MapIterator { + + protected ReferenceMapIterator(AbstractReferenceMap parent) { + super(parent); + } + + public Object next() { + return nextEntry().getKey(); + } + + public Object getKey() { + HashEntry current = currentEntry(); + if (current == null) { + throw new IllegalStateException(AbstractHashedMap.GETKEY_INVALID); + } + return current.getKey(); + } + + public Object getValue() { + HashEntry current = currentEntry(); + if (current == null) { + throw new IllegalStateException(AbstractHashedMap.GETVALUE_INVALID); + } + return current.getValue(); + } + + public Object setValue(Object value) { + HashEntry current = currentEntry(); + if (current == null) { + throw new IllegalStateException(AbstractHashedMap.SETVALUE_INVALID); + } + return current.setValue(value); + } + } + + //----------------------------------------------------------------------- + // These two classes store the hashCode of the key of + // of the mapping, so that after they're dequeued a quick + // lookup of the bucket in the table can occur. + + /** + * A soft reference holder. + */ + static class SoftRef extends SoftReference { + /** the hashCode of the key (even if the reference points to a value) */ + private int hash; + + public SoftRef(int hash, Object r, ReferenceQueue q) { + super(r, q); + this.hash = hash; + } + + public int hashCode() { + return hash; + } + } + + /** + * A weak reference holder. + */ + static class WeakRef extends WeakReference { + /** the hashCode of the key (even if the reference points to a value) */ + private int hash; + + public WeakRef(int hash, Object r, ReferenceQueue q) { + super(r, q); + this.hash = hash; + } + + public int hashCode() { + return hash; + } + } + + //----------------------------------------------------------------------- + /** + * Replaces the superclass method to store the state of this class. + *

+ * Serialization is not one of the JDK's nicest topics. Normal serialization will + * initialise the superclass before the subclass. Sometimes however, this isn't + * what you want, as in this case the put() method on read can be + * affected by subclass state. + *

+ * The solution adopted here is to serialize the state data of this class in + * this protected method. This method must be called by the + * writeObject() of the first serializable subclass. + *

+ * Subclasses may override if they have a specific field that must be present + * on read before this implementation will work. Generally, the read determines + * what must be serialized here, if anything. + * + * @param out the output stream + */ + protected void doWriteObject(ObjectOutputStream out) throws IOException { + out.writeInt(keyType); + out.writeInt(valueType); + out.writeBoolean(purgeValues); + out.writeFloat(loadFactor); + out.writeInt(data.length); + for (MapIterator it = mapIterator(); it.hasNext();) { + out.writeObject(it.next()); + out.writeObject(it.getValue()); + } + out.writeObject(null); // null terminate map + // do not call super.doWriteObject() as code there doesn't work for reference map + } + + /** + * Replaces the superclassm method to read the state of this class. + *

+ * Serialization is not one of the JDK's nicest topics. Normal serialization will + * initialise the superclass before the subclass. Sometimes however, this isn't + * what you want, as in this case the put() method on read can be + * affected by subclass state. + *

+ * The solution adopted here is to deserialize the state data of this class in + * this protected method. This method must be called by the + * readObject() of the first serializable subclass. + *

+ * Subclasses may override if the subclass has a specific field that must be present + * before put() or calculateThreshold() will work correctly. + * + * @param in the input stream + */ + protected void doReadObject(ObjectInputStream in) throws IOException, ClassNotFoundException { + this.keyType = in.readInt(); + this.valueType = in.readInt(); + this.purgeValues = in.readBoolean(); + this.loadFactor = in.readFloat(); + int capacity = in.readInt(); + init(); + data = new HashEntry[capacity]; + while (true) { + Object key = in.readObject(); + if (key == null) { + break; + } + Object value = in.readObject(); + put(key, value); + } + threshold = calculateThreshold(data.length, loadFactor); + // do not call super.doReadObject() as code there doesn't work for reference map + } + +} diff --git a/src/org/apache/commons/collections/map/ReferenceMap.java b/src/org/apache/commons/collections/map/ReferenceMap.java new file mode 100644 index 000000000..5808decd1 --- /dev/null +++ b/src/org/apache/commons/collections/map/ReferenceMap.java @@ -0,0 +1,169 @@ +/* + * 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. + */ +package org.apache.commons.collections.map; + +import java.io.IOException; +import java.io.ObjectInputStream; +import java.io.ObjectOutputStream; +import java.io.Serializable; + +/** + * A Map implementation that allows mappings to be + * removed by the garbage collector. + *

+ * When you construct a ReferenceMap, you can specify what kind + * of references are used to store the map's keys and values. + * If non-hard references are used, then the garbage collector can remove + * mappings if a key or value becomes unreachable, or if the JVM's memory is + * running low. For information on how the different reference types behave, + * see {@link java.lang.ref.Reference Reference}. + *

+ * Different types of references can be specified for keys and values. + * The keys can be configured to be weak but the values hard, + * in which case this class will behave like a + * + * WeakHashMap. However, you can also specify hard keys and + * weak values, or any other combination. The default constructor uses + * hard keys and soft values, providing a memory-sensitive cache. + *

+ * This map is similar to + * {@link org.apache.commons.collections.map.ReferenceIdentityMap ReferenceIdentityMap}. + * It differs in that keys and values in this class are compared using equals(). + *

+ * This {@link java.util.Map Map} implementation does not allow null elements. + * Attempting to add a null key or value to the map will raise a NullPointerException. + *

+ * This implementation is not synchronized. + * You can use {@link java.util.Collections#synchronizedMap} to + * provide synchronized access to a ReferenceMap. + * Remember that synchronization will not stop the garbage collecter removing entries. + *

+ * All the available iterators can be reset back to the start by casting to + * ResettableIterator and calling reset(). + *

+ * Note that ReferenceMap is not synchronized and is not thread-safe. + * If you wish to use this map from multiple threads concurrently, you must use + * appropriate synchronization. The simplest approach is to wrap this map + * using {@link java.util.Collections#synchronizedMap}. This class may throw + * exceptions when accessed by concurrent threads without synchronization. + *

+ * NOTE: As from Commons Collections 3.1 this map extends AbstractReferenceMap + * (previously it extended AbstractMap). As a result, the implementation is now + * extensible and provides a MapIterator. + * + * @see java.lang.ref.Reference + * + * @since Commons Collections 3.0 (previously in main package v2.1) + * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $ + * + * @author Paul Jack + * @author Stephen Colebourne + */ +public class ReferenceMap extends AbstractReferenceMap implements Serializable { + + /** Serialization version */ + private static final long serialVersionUID = 1555089888138299607L; + + /** + * Constructs a new ReferenceMap that will + * use hard references to keys and soft references to values. + */ + public ReferenceMap() { + super(HARD, SOFT, DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, false); + } + + /** + * Constructs a new ReferenceMap that will + * use the specified types of references. + * + * @param keyType the type of reference to use for keys; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param valueType the type of reference to use for values; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + */ + public ReferenceMap(int keyType, int valueType) { + super(keyType, valueType, DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, false); + } + + /** + * Constructs a new ReferenceMap that will + * use the specified types of references. + * + * @param keyType the type of reference to use for keys; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param valueType the type of reference to use for values; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param purgeValues should the value be automatically purged when the + * key is garbage collected + */ + public ReferenceMap(int keyType, int valueType, boolean purgeValues) { + super(keyType, valueType, DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR, purgeValues); + } + + /** + * Constructs a new ReferenceMap with the + * specified reference types, load factor and initial + * capacity. + * + * @param keyType the type of reference to use for keys; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param valueType the type of reference to use for values; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param capacity the initial capacity for the map + * @param loadFactor the load factor for the map + */ + public ReferenceMap(int keyType, int valueType, int capacity, float loadFactor) { + super(keyType, valueType, capacity, loadFactor, false); + } + + /** + * Constructs a new ReferenceMap with the + * specified reference types, load factor and initial + * capacity. + * + * @param keyType the type of reference to use for keys; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param valueType the type of reference to use for values; + * must be {@link #HARD}, {@link #SOFT}, {@link #WEAK} + * @param capacity the initial capacity for the map + * @param loadFactor the load factor for the map + * @param purgeValues should the value be automatically purged when the + * key is garbage collected + */ + public ReferenceMap(int keyType, int valueType, int capacity, + float loadFactor, boolean purgeValues) { + super(keyType, valueType, capacity, loadFactor, purgeValues); + } + + //----------------------------------------------------------------------- + /** + * Write the map out using a custom routine. + */ + private void writeObject(ObjectOutputStream out) throws IOException { + out.defaultWriteObject(); + doWriteObject(out); + } + + /** + * Read the map in using a custom routine. + */ + private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { + in.defaultReadObject(); + doReadObject(in); + } + +}