package org.codehaus.groovy.reflection;
import org.codehaus.groovy.util.ManagedConcurrentMap;
import org.codehaus.groovy.util.ReferenceBundle;
/** Approximation of Java 7's {@link java.lang.ClassValue} that works on earlier versions of Java.
* Note that this implementation isn't as good at Java 7's; it doesn't allow for some GC'ing that Java 7 would allow.
* But, it's good enough for our use.
*
* @param <T>
*/
class GroovyClassValuePreJava7<T> implements GroovyClassValue<T> {
private static final ReferenceBundle weakBundle = ReferenceBundle.getWeakBundle();
private class EntryWithValue extends ManagedConcurrentMap.EntryWithValue<Class<?>,T>{
public EntryWithValue(GroovyClassValuePreJava7Segment segment, Class<?> key, int hash) {
super(weakBundle, segment, key, hash, computeValue.computeValue(key));
}
@Override
public void setValue(T value) {
if(value!=null) super.setValue(value);
}
}
private class GroovyClassValuePreJava7Segment extends ManagedConcurrentMap.Segment<Class<?>,T> {
GroovyClassValuePreJava7Segment(ReferenceBundle bundle, int initialCapacity) {
super(bundle, initialCapacity);
}
@Override
protected EntryWithValue createEntry(Class<?> key, int hash,
T unused) {
return new EntryWithValue(this, key, hash);
}
}
private class GroovyClassValuePreJava7Map extends ManagedConcurrentMap<Class<?>,T> {
public GroovyClassValuePreJava7Map() {
super(weakBundle);
}
@Override
protected GroovyClassValuePreJava7Segment createSegment(Object segmentInfo, int cap) {
ReferenceBundle bundle = (ReferenceBundle) segmentInfo;
if (bundle==null) throw new IllegalArgumentException("bundle must not be null ");
return new GroovyClassValuePreJava7Segment(bundle, cap);
}
}
private final ComputeValue<T> computeValue;
private final GroovyClassValuePreJava7Map map = new GroovyClassValuePreJava7Map();
public GroovyClassValuePreJava7(ComputeValue<T> computeValue){
this.computeValue = computeValue;
}
@Override
public T get(Class<?> type) {
// the value isn't use in the getOrPut call - see the EntryWithValue constructor above
T value = ((EntryWithValue)map.getOrPut(type, null)).getValue();
//all entries are guaranteed to be EntryWithValue. Value can only be null if computeValue returns null
return value;
}
@Override
public void remove(Class<?> type) {
map.remove(type);
}
}