/*
 * FindBugs - Find bugs in Java programs
 * Copyright (C) 2004-2006 University of Maryland
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package edu.umd.cs.findbugs;

import java.util.Map;

import edu.umd.cs.findbugs.classfile.Global;

public class AnalysisLocal<T> {
    protected T initialValue() {
        return null;
    }

    @SuppressWarnings("unchecked")
    protected Map<AnalysisLocal<T>, T> getMap() {
        Map<?, ?> m = Global.getAnalysisCache().getAnalysisLocals();
        return (Map<AnalysisLocal<T>, T>) m;
    }

    public T get() {
        Map<AnalysisLocal<T>, T> m = getMap();

        if (m.containsKey(this)) {
            return m.get(this);
        }

        synchronized (m) {
            if (m.containsKey(this)) {
                return m.get(this);
            }
            T result = initialValue();
            m.put(this, result);
            return result;
        }
    }

    public void set(T value) {
        Map<AnalysisLocal<T>, T> m = getMap();
        m.put(this, value);
    }

    public void remove() {
        Map<AnalysisLocal<T>, T> m = getMap();
        m.remove(this);
    }
}