4 files changed, 65 insertions, 50 deletions

diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/internal/apiimpl/ViatraQueryEngineImpl.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/internal/apiimpl/ViatraQueryEngineImpl.java
index 5317a79e..84ac8f7d 100644
--- a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/internal/apiimpl/ViatraQueryEngineImpl.java
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/internal/apiimpl/ViatraQueryEngineImpl.java
@@ -74,7 +74,7 @@ public final class ViatraQueryEngineImpl extends AdvancedViatraQueryEngine
     /**
      * The context of the engine, provided by the scope.
      */
-    private IEngineContext engineContext;
+    private final IEngineContext engineContext;
 
     /**
      * Initialized matchers for each query
@@ -85,7 +85,7 @@ public final class ViatraQueryEngineImpl extends AdvancedViatraQueryEngine
     /**
      * The RETE and other pattern matcher implementations of the VIATRA Query Engine.
      */
-    private volatile Map<IQueryBackendFactory, IQueryBackend> queryBackends = new HashMap<>();
+    private final Map<IQueryBackendFactory, IQueryBackend> queryBackends = Collections.synchronizedMap(new HashMap<>());
 
     /**
      * The current engine default hints
diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/context/common/JavaTransitiveInstancesKey.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/context/common/JavaTransitiveInstancesKey.java
index eb972c2d..400a6ab9 100644
--- a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/context/common/JavaTransitiveInstancesKey.java
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/context/common/JavaTransitiveInstancesKey.java
@@ -3,7 +3,7 @@
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
  * http://www.eclipse.org/legal/epl-v20.html.
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0
  *******************************************************************************/
 package tools.refinery.viatra.runtime.matchers.context.common;
@@ -12,22 +12,22 @@ package tools.refinery.viatra.runtime.matchers.context.common;
 
 /**
  * Instance tuples are of form (x), where object x is an instance of the given Java class or its subclasses.
- * <p> Fine print 1: classes with the same name are considered equivalent. 
- * Can be instantiated with class name, even if the class itself is not loaded yet; but if the class is available, passing it in the constructor is beneficial to avoid classloading troubles.  
- * <p> Fine print 2: primitive types (char, etc.) are transparently treated as their wrapper class (Character, etc.). 
+ * <p> Fine print 1: classes with the same name are considered equivalent.
+ * Can be instantiated with class name, even if the class itself is not loaded yet; but if the class is available, passing it in the constructor is beneficial to avoid classloading troubles.
+ * <p> Fine print 2: primitive types (char, etc.) are transparently treated as their wrapper class (Character, etc.).
  * <p> Non-enumerable type, can only be checked.
  * <p> Stateless type (objects can't change their type)
  * @author Bergmann Gabor
  *
 */
 public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
-    
+
     /**
      * The actual Class whose (transitive) instances this relation contains. Can be null at compile time, if only the name is available.
-     * Can be a primitive.  
+     * Can be a primitive.
      */
     private Class<?> cachedOriginalInstanceClass;
-    
+
     /**
      * Same as {@link #cachedOriginalInstanceClass}, but primitive classes are replaced with their wrapper classes (e.g. int --> java.lang.Integer).
      */
@@ -37,17 +37,17 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
      * Preferred constructor.
      */
     public JavaTransitiveInstancesKey(Class<?> instanceClass) {
-        this(primitiveTypeToWrapperClass(instanceClass).getName());
+        this(getName(instanceClass));
         this.cachedOriginalInstanceClass = instanceClass;
     }
-    
+
     /**
      * Call this constructor only in contexts where the class itself is not available for loading, e.g. it has not yet been compiled.
      */
     public JavaTransitiveInstancesKey(String className) {
         super(className);
     }
-    
+
 
     /**
      * Returns null if class cannot be loaded.
@@ -66,7 +66,7 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
 
     /**
      * @return non-null instance class
-     * @throws ClassNotFoundException 
+     * @throws ClassNotFoundException
      */
     private Class<?> forceGetOriginalInstanceClass() throws ClassNotFoundException {
         if (cachedOriginalInstanceClass == null) {
@@ -74,10 +74,10 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
         }
         return cachedOriginalInstanceClass;
     }
-    
+
     /**
      * @return non-null instance class, wrapped if primitive class
-     * @throws ClassNotFoundException 
+     * @throws ClassNotFoundException
      */
     public Class<?> forceGetWrapperInstanceClass() throws ClassNotFoundException {
         forceGetOriginalInstanceClass();
@@ -85,12 +85,12 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
     }
     /**
      * @return non-null instance class, wrapped if primitive class
-     * @throws ClassNotFoundException 
+     * @throws ClassNotFoundException
      */
     public Class<?> forceGetInstanceClass() throws ClassNotFoundException {
         return forceGetWrapperInstanceClass();
     }
-    
+
     /**
      * @return instance class, wrapped if primitive class, null if class cannot be loaded
      */
@@ -106,16 +106,19 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
     public Class<?> getInstanceClass()  {
         return getWrapperInstanceClass();
     }
-    
+
     private void resolveClassInternal() throws ClassNotFoundException {
         cachedOriginalInstanceClass = Class.forName(wrappedKey);
     }
-    
+
     @Override
     public String getPrettyPrintableName() {
         getWrapperInstanceClass();
-        return cachedWrapperInstanceClass == null ? wrappedKey == null ? "<null>" : wrappedKey : cachedWrapperInstanceClass.getName();
-    }
+                if (cachedWrapperInstanceClass == null) {
+                        return wrappedKey == null ? "<null>" : wrappedKey;
+                }
+                return cachedWrapperInstanceClass.getName();
+        }
 
     @Override
     public String getStringID() {
@@ -126,12 +129,12 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
     public int getArity() {
         return 1;
     }
-    
+
     @Override
     public boolean isEnumerable() {
         return false;
     }
-    
+
     @Override
     public String toString() {
         return this.getPrettyPrintableName();
@@ -161,5 +164,11 @@ public class JavaTransitiveInstancesKey extends BaseInputKeyWrapper<String> {
         return instanceClass;
     }
 
-
+        private static String getName(Class<?> instanceClass) {
+                Class<?> wrapperClass = primitiveTypeToWrapperClass(instanceClass);
+                if (wrapperClass == null) {
+                        return "<null>";
+                }
+                return wrapperClass.getName();
+        }
 }
diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/rewriters/VariableMappingExpressionEvaluatorWrapper.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/rewriters/VariableMappingExpressionEvaluatorWrapper.java
index 10337979..e0e17b5e 100644
--- a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/rewriters/VariableMappingExpressionEvaluatorWrapper.java
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/psystem/rewriters/VariableMappingExpressionEvaluatorWrapper.java
@@ -3,24 +3,24 @@
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
  * http://www.eclipse.org/legal/epl-v20.html.
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0
  *******************************************************************************/
 package tools.refinery.viatra.runtime.matchers.psystem.rewriters;
 
-import java.util.HashMap;
-import java.util.LinkedHashMap;
-import java.util.Map;
-
 import tools.refinery.viatra.runtime.matchers.psystem.IExpressionEvaluator;
 import tools.refinery.viatra.runtime.matchers.psystem.IValueProvider;
 import tools.refinery.viatra.runtime.matchers.psystem.PVariable;
 import tools.refinery.viatra.runtime.matchers.util.Preconditions;
 
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+
 /**
  * A wrapper for {@link IExpressionEvaluator} which is capable of correctly mapping variable names used by the
  * expression.
- * 
+ *
  * @author Grill Balázs
  *
  */
@@ -28,10 +28,10 @@ class VariableMappingExpressionEvaluatorWrapper implements IExpressionEvaluator
 
     private final IExpressionEvaluator wrapped;
     private final Map<String, String> variableMapping;
-    
+
     public VariableMappingExpressionEvaluatorWrapper(IExpressionEvaluator wrapped,
             Map<PVariable, PVariable> variableMapping) {
-        
+
         // Support to rewrap an already wrapped expression.
         boolean rewrap = wrapped instanceof VariableMappingExpressionEvaluatorWrapper;
         this.wrapped = rewrap ? ((VariableMappingExpressionEvaluatorWrapper)wrapped).wrapped : wrapped;
@@ -46,7 +46,7 @@ class VariableMappingExpressionEvaluatorWrapper implements IExpressionEvaluator
         for (PVariable originalVar : variableMapping.keySet()) {
             names.put(originalVar.getName(), originalVar);
         }
-        
+
         // In case of rewrapping, current names are contained by the previous mapping
         Map<String, String> previousMapping = null;
         if (rewrap){
@@ -55,6 +55,8 @@ class VariableMappingExpressionEvaluatorWrapper implements IExpressionEvaluator
 
         // Populate mapping
         for (String inputParameterName : this.wrapped.getInputParameterNames()) {
+                        // {@code previousMapping} can't be {@code null} if {@code rewrap} is {@code true}.
+                        @SuppressWarnings("squid:S2259")
             String parameterName = rewrap ? previousMapping.get(inputParameterName) : inputParameterName;
             Preconditions.checkArgument(parameterName != null);
             PVariable original = names.get(parameterName);
diff --git a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/EclipseCollectionsLongSetMemory.java b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/EclipseCollectionsLongSetMemory.java
index fceb54fc..ce3efa92 100644
--- a/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/EclipseCollectionsLongSetMemory.java
+++ b/subprojects/viatra-runtime/src/main/java/tools/refinery/viatra/runtime/matchers/util/EclipseCollectionsLongSetMemory.java
@@ -3,20 +3,21 @@
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0 which is available at
  * http://www.eclipse.org/legal/epl-v20.html.
- * 
+ *
  * SPDX-License-Identifier: EPL-2.0
  *******************************************************************************/
 package tools.refinery.viatra.runtime.matchers.util;
 
-import java.util.Collection;
-import java.util.Iterator;
-import java.util.Set;
-
 import org.eclipse.collections.api.LongIterable;
 import org.eclipse.collections.api.iterator.LongIterator;
 import org.eclipse.collections.api.set.primitive.LongSet;
 import org.eclipse.collections.impl.set.mutable.primitive.LongHashSet;
 
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.Set;
+
 /**
  * @author Gabor Bergmann
  * @since 2.0
@@ -31,7 +32,7 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
     @Override
     public boolean addSigned(Long value, int count) {
         if (count == 1) return addOne(value);
-        else if (count == -1) return removeOne(value); 
+        else if (count == -1) return removeOne(value);
         else throw new IllegalStateException();
     }
 
@@ -40,7 +41,7 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
         // Kept for binary compatibility
         return ISetMemory.super.removeOne(value);
     }
-    
+
     /**
      * @since 2.3
      */
@@ -58,7 +59,7 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
     public int getCount(Long value) {
         return super.contains(value) ? 1 : 0;
     }
-    
+
     @Override
     public int getCountUnsafe(Object value) {
         return value instanceof Long ? getCount((Long) value) : 0;
@@ -68,7 +69,7 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
     public boolean containsNonZero(Long value) {
         return super.contains(value);
     }
-    
+
     @Override
     public boolean containsNonZeroUnsafe(Object value) {
         return value instanceof Long && containsNonZero((Long) value);
@@ -83,18 +84,18 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
     public Set<Long> distinctValues() {
         return new SetWrapper(this);
     }
-    
+
     @Override
     public boolean isEmpty() {
         return super.isEmpty();
     }
-    
+
     /**
      * Helper for iterating a LongIterable
      */
     public static Iterator<Long> iteratorOf(LongIterable wrapped) {
         return new Iterator<Long>() {
-            LongIterator longIterator = wrapped.longIterator();
+            private final LongIterator longIterator = wrapped.longIterator();
 
             @Override
             public boolean hasNext() {
@@ -103,11 +104,14 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
 
             @Override
             public Long next() {
+                                if (!longIterator.hasNext()) {
+                                        throw new NoSuchElementException("next() called, but the iterator is exhausted");
+                                }
                 return longIterator.next();
             }
         };
     }
-    
+
     @Override
     public int hashCode() {
         return IMemoryView.hashCode(this);
@@ -117,7 +121,7 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
         return IMemoryView.equals(this, obj);
     }
 
-    
+
     /**
      * Helper that presents a primitive collection as a Set view
      * @author Gabor Bergmann
@@ -171,7 +175,7 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
         public <T> T[] toArray(T[] a) {
             int k = 0;
             LongIterator iterator = wrapped.longIterator();
-            while (iterator.hasNext()) 
+            while (iterator.hasNext())
                 a[k++] = (T) Long.valueOf(iterator.next());
             return a;
         }
@@ -205,8 +209,8 @@ public class EclipseCollectionsLongSetMemory extends LongHashSet implements ISet
         public void clear() {
             throw new UnsupportedOperationException();
         }
-        
-        
+
+
     }
 
 }