1 /*
   2  * Copyright (c) 2017, 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 package jdk.internal.module;
  26 
  27 import java.lang.module.ModuleDescriptor;
  28 import java.lang.module.ModuleFinder;
  29 import java.lang.module.ModuleReference;
  30 import java.util.HashSet;
  31 import java.util.Set;
  32 
  33 /**
  34  * Defines methods to compute the default set of root modules for the unnamed
  35  * module.
  36  */
  37 
  38 public final class DefaultRoots {
  39     private static final String JAVA_SE = "java.se";
  40 
  41     private DefaultRoots() { }
  42 
  43     /**
  44      * Returns the default set of root modules for the unnamed module computed from
  45      * the system modules observable with the given module finder.
  46      */
  47     static Set<String> compute(ModuleFinder systemModuleFinder, ModuleFinder finder) {
  48         Set<String> roots = new HashSet<>();
  49 
  50         boolean hasJava = false;
  51         if (systemModuleFinder.find(JAVA_SE).isPresent()) {
  52             if (finder == systemModuleFinder || finder.find(JAVA_SE).isPresent()) {
  53                 // java.se is a system module
  54                 hasJava = true;
  55                 roots.add(JAVA_SE);
  56             }
  57         }
  58 
  59         for (ModuleReference mref : systemModuleFinder.findAll()) {
  60             String mn = mref.descriptor().name();
  61             if (hasJava && mn.startsWith("java.")) {
  62                 // not a root
  63                 continue;
  64             }
  65 
  66             if (ModuleResolution.doNotResolveByDefault(mref)) {
  67                 // not a root
  68                 continue;
  69             }
  70 
  71             if ((finder == systemModuleFinder || finder.find(mn).isPresent())) {
  72                 // add as root if exports at least one package to all modules
  73                 ModuleDescriptor descriptor = mref.descriptor();
  74                 for (ModuleDescriptor.Exports e : descriptor.exports()) {
  75                     if (!e.isQualified()) {
  76                         roots.add(mn);
  77                         break;
  78                     }
  79                 }
  80             }
  81         }
  82 
  83         return roots;
  84     }
  85 
  86     /**
  87      * Returns the default set of root modules for the unnamed module from the
  88      * modules observable with the given module finder.
  89      */
  90     public static Set<String> compute(ModuleFinder finder) {
  91         return compute(finder, finder);
  92     }
  93 }