/*

 * Copyright (c) 2018, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 jdk.internal.module;

import java.lang.module.ModuleFinder;

import java.util.Objects;

import jdk.internal.misc.VM;

/**

 * Used by ModuleBootstrap to obtain the archived system modules and finder.

 */

final class ArchivedModuleGraph {

    private static String archivedMainModule;

    private static SystemModules archivedSystemModules;

    private static ModuleFinder archivedModuleFinder;

    private final SystemModules systemModules;

    private final ModuleFinder finder;

    private ArchivedModuleGraph(SystemModules modules, ModuleFinder finder) {

        this.systemModules = modules;

        this.finder = finder;

    }

    SystemModules systemModules() {

        return systemModules;

    }

    ModuleFinder finder() {

        return finder;

    }

    // A factory method that ModuleBootstrap can use to obtain the

    // ArchivedModuleGraph.

    static ArchivedModuleGraph get(String mainModule) {

        if (Objects.equals(mainModule, archivedMainModule)

                && archivedSystemModules != null

                && archivedModuleFinder != null) {

            return new ArchivedModuleGraph(archivedSystemModules,

                                           archivedModuleFinder);

        } else {

            return null;

        }

    }

    // Used at CDS dump time

    static void archive(String mainModule, SystemModules systemModules,

                        ModuleFinder finder) {

        if (archivedMainModule != null)

            throw new UnsupportedOperationException();

        archivedMainModule = mainModule;

        archivedSystemModules = systemModules;

        archivedModuleFinder = finder;

    }

    static {

        VM.initializeFromArchive(ArchivedModuleGraph.class);

    }

}