/*

 * Copyright (c) 2015, 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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 General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.graph;

import java.util.function.Consumer;

/**

 * This class is a container of a graph that needs to be readonly and optionally a lazily created

 * mutable copy of the graph.

 */

public final class CachedGraph<G extends Graph> {

    private final G readonlyCopy;

    private G mutableCopy;

    private CachedGraph(G readonlyCopy, G mutableCopy) {

        this.readonlyCopy = readonlyCopy;

        this.mutableCopy = mutableCopy;

    }

    public static <G extends Graph> CachedGraph<G> fromReadonlyCopy(G graph) {

        return new CachedGraph<>(graph, null);

    }

    public static <G extends Graph> CachedGraph<G> fromMutableCopy(G graph) {

        return new CachedGraph<>(graph, graph);

    }

    public G getReadonlyCopy() {

        if (hasMutableCopy()) {

            return mutableCopy;

        }

        return readonlyCopy;

    }

    public boolean hasMutableCopy() {

        return mutableCopy != null;

    }

    @SuppressWarnings("unchecked")

    public G getMutableCopy(Consumer<UnmodifiableEconomicMap<Node, Node>> duplicationMapCallback) {

        if (!hasMutableCopy()) {

            // Sharing the debug context with the copy is safe since both graphs are

            // only used in the current thread.

            mutableCopy = (G) readonlyCopy.copy(duplicationMapCallback, readonlyCopy.getDebug());

        }

        return mutableCopy;

    }

}