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[COLLECTIONS-395] Added LRUMap#get(Object, boolean) to query the map without affecting the lru order. Thanks to David Hawthorne. 

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/collections/trunk@1671832 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Thomas Neidhart 2015-04-07 12:25:18 +00:00
parent 640670bd86
commit 0f4a98cfe1
3 changed files with 75 additions and 4 deletions
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4
src/changes/changes.xml
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@ -22,6 +22,10 @@
<body>
<release version="4.1" date="TBD" description="">
<action issue="COLLECTIONS-395" dev="tn" type="add" due-to="David Hawthorne">
Added method "LRUMap#get(Object, boolean)" that allows to query the map
without affecting the least recently used order.
</action>
<action issue="COLLECTIONS-558" dev="tn" type="fix" due-to="Felix Rabe">
Changed return type of "ListOrderedSet#remove(int)" from Object to the generic type parameter.
</action>

26
src/main/java/org/apache/commons/collections4/map/LRUMap.java
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@ -116,7 +116,7 @@ public class LRUMap<K, V>
* Constructs a new, empty map with the specified initial capacity and
* load factor.
*
* @param maxSize the maximum size of the ma
* @param maxSize the maximum size of the map
* @param loadFactor the load factor
* @param scanUntilRemovable scan until a removeable entry is found, default false
* @throws IllegalArgumentException if the maximum size is less than one
@ -166,18 +166,36 @@ public class LRUMap<K, V>
* Gets the value mapped to the key specified.
* <p>
* This operation changes the position of the key in the map to the
* most recently used position (first).
* most recently used position (last).
*
* @param key the key
* @return the mapped value, null if no match
*/
@Override
public V get(final Object key) {
return get(key, true);
}
/**
* Gets the value mapped to the key specified.
* <p>
* If {@code updateToMRU} is {@code true}, the position of the key in the map
* is changed to the most recently used position (last), otherwise the iteration
* order is not changed by this operation.
*
* @param key the key
* @param updateToMRU whether the key shall be updated to the
* most recently used position
* @return the mapped value, null if no match
*/
public V get(final Object key, final boolean updateToMRU) {
final LinkEntry<K, V> entry = getEntry(key);
if (entry == null) {
return null;
}
moveToMRU(entry);
if (updateToMRU) {
moveToMRU(entry);
}
return entry.getValue();
}
@ -214,7 +232,7 @@ public class LRUMap<K, V>
/**
* Updates an existing key-value mapping.
* <p>
* This implementation moves the updated entry to the top of the list
* This implementation moves the updated entry to the end of the list
* using {@link #moveToMRU(AbstractLinkedMap.LinkEntry)}.
*
* @param entry the entry to update

49
src/test/java/org/apache/commons/collections4/map/LRUMapTest.java
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@ -224,6 +224,55 @@ public class LRUMapTest<K, V> extends AbstractOrderedMapTest<K, V> {
assertSame(values[3], vit.next());
}
public void testAccessOrder2() {
if (!isPutAddSupported() || !isPutChangeSupported()) {
return;
}
final K[] keys = getSampleKeys();
final V[] values = getSampleValues();
Iterator<K> kit = null;
Iterator<V> vit = null;
resetEmpty();
LRUMap<K, V> lruMap = (LRUMap<K, V>) map;
lruMap.put(keys[0], values[0]);
lruMap.put(keys[1], values[1]);
kit = lruMap.keySet().iterator();
assertSame(keys[0], kit.next());
assertSame(keys[1], kit.next());
vit = lruMap.values().iterator();
assertSame(values[0], vit.next());
assertSame(values[1], vit.next());
// no change to order
lruMap.put(keys[1], values[1]);
kit = lruMap.keySet().iterator();
assertSame(keys[0], kit.next());
assertSame(keys[1], kit.next());
vit = lruMap.values().iterator();
assertSame(values[0], vit.next());
assertSame(values[1], vit.next());
// no change to order
lruMap.get(keys[1], false);
kit = lruMap.keySet().iterator();
assertSame(keys[0], kit.next());
assertSame(keys[1], kit.next());
vit = lruMap.values().iterator();
assertSame(values[0], vit.next());
assertSame(values[1], vit.next());
// change to order
lruMap.get(keys[0], true);
kit = lruMap.keySet().iterator();
assertSame(keys[1], kit.next());
assertSame(keys[0], kit.next());
vit = lruMap.values().iterator();
assertSame(values[1], vit.next());
assertSame(values[0], vit.next());
}
@SuppressWarnings("unchecked")
public void testClone() {
final LRUMap<K, V> map = new LRUMap<K, V>(10);