src/java.base/share/classes/jdk/internal/module/ModuleBootstrap.java

rev 57943 : 8238599: Refactor and simplify implAddOpensToAllUnnamed
Reviewed-by: alanb

@@ -798,10 +798,12 @@
             IllegalAccessMaps maps = IllegalAccessMaps.generate(limitedFinder());
             concealedPackagesToOpen = maps.concealedPackagesToOpen();
             exportedPackagesToOpen = maps.exportedPackagesToOpen();
         }
 
+        Set<String> emptySet = Set.of();
+
         // open specific packages in the system modules
         for (Module m : bootLayer.modules()) {
             ModuleDescriptor descriptor = m.getDescriptor();
             String name = m.getName();
 

@@ -814,12 +816,12 @@
             if (upgradeModulePath != null
                 && upgradeModulePath.find(name).isPresent()) {
                 continue;
             }
 
-            Set<String> concealedPackages = concealedPackagesToOpen.getOrDefault(name, Set.of());
-            Set<String> exportedPackages = exportedPackagesToOpen.getOrDefault(name, Set.of());
+            Set<String> concealedPackages = concealedPackagesToOpen.getOrDefault(name, emptySet);
+            Set<String> exportedPackages = exportedPackagesToOpen.getOrDefault(name, emptySet);
 
             // refresh the set of concealed and exported packages if needed
             if (extraExportsOrOpens) {
                 concealedPackages = new HashSet<>(concealedPackages);
                 exportedPackages = new HashSet<>(exportedPackages);

@@ -848,12 +850,11 @@
             // log reflective access to non-public members/types in exported packages
             builder.logAccessToExportedPackages(m, exportedPackages);
 
             // open the packages to unnamed modules
             JavaLangAccess jla = SharedSecrets.getJavaLangAccess();
-            jla.addOpensToAllUnnamed(m, concat(concealedPackages.iterator(),
-                                               exportedPackages.iterator()));
+            jla.addOpensToAllUnnamed(m, concealedPackages, exportedPackages);
         }
 
         builder.complete();
     }
 

@@ -994,29 +995,10 @@
                 throw new IllegalArgumentException(prefix);
         }
     }
 
     /**
-     * Returns an iterator that yields all elements of the first iterator
-     * followed by all the elements of the second iterator.
-     */
-    static <T> Iterator<T> concat(Iterator<T> iterator1, Iterator<T> iterator2) {
-        return new Iterator<T>() {
-            @Override
-            public boolean hasNext() {
-                return iterator1.hasNext() || iterator2.hasNext();
-            }
-            @Override
-            public T next() {
-                if (iterator1.hasNext()) return iterator1.next();
-                if (iterator2.hasNext()) return iterator2.next();
-                throw new NoSuchElementException();
-            }
-        };
-    }
-
-    /**
      * Wraps a (potentially not thread safe) ModuleFinder created during startup
      * for use after startup.
      */
     static class SafeModuleFinder implements ModuleFinder {
         private final Set<ModuleReference> mrefs;