1 /*
   2  * Copyright (c) 2017, 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.internal.module;
  27 
  28 import java.lang.module.ModuleDescriptor;
  29 import java.lang.module.ModuleFinder;
  30 import java.lang.module.ModuleReference;
  31 import java.util.Set;
  32 import java.util.stream.Collectors;
  33 
  34 /**
  35  * Defines methods to compute the default set of root modules for the unnamed
  36  * module.
  37  */
  38 
  39 public final class DefaultRoots {
  40     private DefaultRoots() { }
  41 
  42     /**
  43      * Returns the default set of root modules for the unnamed module from the
  44      * modules observable with the intersection of two module finders.
  45      *
  46      * The first module finder should be the module finder that finds modules on
  47      * the upgrade module path or among the system modules. The second module
  48      * finder should be the module finder that finds all modules on the module
  49      * path, or a subset of when using --limit-modules.
  50      */
  51     static Set<String> compute(ModuleFinder finder1, ModuleFinder finder2) {
  52         return finder1.findAll().stream()
  53                 .filter(mref -> !ModuleResolution.doNotResolveByDefault(mref))
  54                 .map(ModuleReference::descriptor)
  55                 .filter(descriptor -> finder2.find(descriptor.name()).isPresent()
  56                                       && exportsAPI(descriptor))
  57                 .map(ModuleDescriptor::name)
  58                 .collect(Collectors.toSet());
  59     }
  60 
  61     /**
  62      * Returns the default set of root modules for the unnamed module from the
  63      * modules observable with the given module finder.
  64      *
  65      * This method is used by the jlink system modules plugin.
  66      */
  67     public static Set<String> compute(ModuleFinder finder) {
  68         return compute(finder, finder);
  69     }
  70 
  71     /**
  72      * Returns true if the given module exports a package to all modules
  73      */
  74     private static boolean exportsAPI(ModuleDescriptor descriptor) {
  75         return descriptor.exports()
  76                 .stream()
  77                 .filter(e -> !e.isQualified())
  78                 .findAny()
  79                 .isPresent();
  80     }
  81 }