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The AspectJ matcher can be used for matching pointcuts independently of any AspectJ compilation or weaving steps. Most notably, this can be used by frameworks such as Spring AOP which utilise the @AspectJ pointcut syntax but implement aspect weaving in a way independent of AspectJ, e.g. using dynamic proxies.

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/* *******************************************************************
 * Copyright (c) 2017 Contributors
 * All rights reserved.
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Public License v 2.0
 * which accompanies this distribution and is available at
 * https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.txt
 * ******************************************************************/package org.aspectj.util;

import java.lang.ref.ReferenceQueue;
import java.lang.ref.SoftReference;
import java.util.AbstractMap;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

public class SoftHashMap extends AbstractMap {
	private Map map;
	private ReferenceQueue rq = new ReferenceQueue();

	public SoftHashMap() {
		this.map = new HashMap<>();
	}

	class SpecialValue extends SoftReference {
		private final K key;

		SpecialValue(K k, V v) {
			super(v, rq);
			this.key = k;
		}
	}

	@SuppressWarnings("unchecked")
	private void processQueue() {
		SpecialValue sv = null;
		while ((sv = (SpecialValue)rq.poll()) != null) {
			map.remove(sv.key);
		}
	}

	@Override
	public V get(Object key) {
		SpecialValue ref = map.get(key);
		if (ref == null) {
			map.remove(key);
			return null;
		}
		V value = ref.get();
		if (value == null) {
			map.remove(ref.key);
			return null;
		}
		return value;
	}

	@Override
	public V put(K k, V v) {
		processQueue();
		SpecialValue sv = new SpecialValue(k, v);
		SpecialValue result = map.put(k, sv);
		return (result == null ? null : result.get());
	}

	@Override
	public java.util.Set> entrySet() {
		if (map.isEmpty()) { return Collections.emptyMap().entrySet(); }
		Map currentContents = new HashMap<>();
		for (Map.Entry entry: map.entrySet()) {
			V currentValueForEntry = entry.getValue().get();
			if (currentValueForEntry != null) {
				currentContents.put(entry.getKey(), currentValueForEntry);
			}
		}
		return currentContents.entrySet();
	}

	@Override
	public void clear() {
		processQueue();
		map.clear();
	}

	@Override
	public int size() {
		processQueue();
		return map.size();
	}

	@Override
	public V remove(Object k) {
		processQueue();
		SpecialValue ref = map.remove(k);
		if (ref == null) {
			return null;
		}
		return ref.get();
	}
}