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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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.
 *
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package jdk.internal.module;

import java.lang.module.ModuleDescriptor;
import java.lang.module.ModuleFinder;
import java.lang.module.ModuleReference;
import java.util.Set;
import java.util.stream.Collectors;

Defines methods to compute the default set of root modules for the unnamed
module.
/**
 * Defines methods to compute the default set of root modules for the unnamed
 * module.
 */

public final class DefaultRoots {
    private DefaultRoots() { }

    
Returns the default set of root modules for the unnamed module from the
modules observable with the intersection of two module finders.
The first module finder should be the module finder that finds modules on
the upgrade module path or among the system modules. The second module
finder should be the module finder that finds all modules on the module
path, or a subset of when using --limit-modules.
/**
     * Returns the default set of root modules for the unnamed module from the
     * modules observable with the intersection of two module finders.
     *
     * The first module finder should be the module finder that finds modules on
     * the upgrade module path or among the system modules. The second module
     * finder should be the module finder that finds all modules on the module
     * path, or a subset of when using --limit-modules.
     */
    static Set<String> compute(ModuleFinder finder1, ModuleFinder finder2) {
        return finder1.findAll().stream()
                .filter(mref -> !ModuleResolution.doNotResolveByDefault(mref))
                .map(ModuleReference::descriptor)
                .filter(descriptor -> finder2.find(descriptor.name()).isPresent()
                                      && exportsAPI(descriptor))
                .map(ModuleDescriptor::name)
                .collect(Collectors.toSet());
    }

    
Returns the default set of root modules for the unnamed module from the
modules observable with the given module finder.
This method is used by the jlink system modules plugin.
/**
     * Returns the default set of root modules for the unnamed module from the
     * modules observable with the given module finder.
     *
     * This method is used by the jlink system modules plugin.
     */
    public static Set<String> compute(ModuleFinder finder) {
        return compute(finder, finder);
    }

    
Returns true if the given module exports a package to all modules
/**
     * Returns true if the given module exports a package to all modules
     */
    private static boolean exportsAPI(ModuleDescriptor descriptor) {
        return descriptor.exports()
                .stream()
                .filter(e -> !e.isQualified())
                .findAny()
                .isPresent();
    }
}