[ji] do not assume map entry-set size == map.size

kares · kares · commit 40f40fb9fae3 · 2019-07-14T20:58:32.000+02:00
as we're getting a NPE on newer Rhino (~ 1.7.8) inspect-ing
the global object (which implements java.util.Map) and reports
a size &gt; 0 but only returns user inserted entries by default
diff --git a/core/src/main/java/org/jruby/java/proxies/MapJavaProxy.java b/core/src/main/java/org/jruby/java/proxies/MapJavaProxy.java
@@ -104,6 +104,7 @@ private RubyHashMap getOrCreateRubyHashMap() {
 
     private static final class RubyHashMap extends RubyHash {
         static final RubyHashEntry[] EMPTY_TABLE = new RubyHashEntry[0];
+        private static final Map.Entry[] NULL_MAP_ENTRY = new Map.Entry[0];
 
         private final MapJavaProxy receiver;
 
@@ -264,7 +265,7 @@ public <T> void visitAll(ThreadContext context, VisitorWithState visitor, T stat
             // NOTE: this is here to make maps act similar to Hash-es which allow modifications while
             // iterating (meant from the same thread) ... thus we avoid iterating entrySet() directly
             final Map<Object, Object> map = mapDelegate();
-            final Map.Entry[] entries = map.entrySet().toArray( new Map.Entry[map.size() ] );
+            final Map.Entry[] entries = map.entrySet().toArray(NULL_MAP_ENTRY);
             int index = 0;
             for ( Map.Entry entry : entries ) {
                 IRubyObject key = JavaUtil.convertJavaToUsableRubyObject(runtime, entry.getKey());
diff --git a/spec/java_integration/fixtures/InternalMap.java b/spec/java_integration/fixtures/InternalMap.java
@@ -0,0 +1,29 @@
+package java_integration.fixtures;
+
+import java.util.*;
+import java.util.stream.Collectors;
+
+public class InternalMap<K, V> extends AbstractMap<K, V> {
+
+    private final AbstractSet<Map.Entry<K,V>> entries = new HashSet<>();
+
+    public V put(K key, V value) {
+        Optional<Map.Entry<K,V>> entry = entries.stream().filter((e) -> e.getKey().equals(key)).findFirst();
+        if (entry.isPresent()) {
+            entries.remove(entry.get());
+        }
+
+        entries.add(new SimpleEntry(key, value));
+
+        return entry.isPresent() ? entry.get().getValue() : null;
+    }
+
+    public Set<Map.Entry<K,V>> entrySet() {
+        return entries.stream().filter((e) -> !e.getKey().toString().startsWith("_")).collect(Collectors.toSet());
+    }
+
+    public int size() {
+        return entries.size();
+    }
+
+}
diff --git a/spec/java_integration/types/map_spec.rb b/spec/java_integration/types/map_spec.rb
@@ -358,6 +358,23 @@ class H1 < java.util.HashMap
     expect( map.to_h ).to eql({ 1 => 1, 2 => :dva, 3 => 3, 4 => 0.1 })
   end
 
+  # Rhino's scopes (implements Map) behave in a similar way
+  it 'properly handles (internal) filtering map' do
+    map = Java::java_integration::fixtures::InternalMap.new
+    map['_internal_1'] = 1
+    map['_internal_2'] = 2
+    expect( map.size() ).to eql 2
+    expect( map.inspect ).to eql '{}'
+    yielded = {}
+    map.each { |key, val| yielded[key] = val }
+    expect(yielded).to be_empty
+
+    map['proper_key'] = 3
+    expect( map.size() ).to eql 3
+    expect( map.inspect ).to_not eql '{}'
+    expect(map.keys).to eql ['proper_key']
+  end
+
   private
 
   if {}.respond_to? :key
