1 files changed, 114 insertions, 0 deletions

diff --git a/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/aggregation/GroupedSet.java b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/aggregation/GroupedSet.java
new file mode 100644
index 00000000..65561e53
--- /dev/null
+++ b/subprojects/viatra-runtime-rete/src/main/java/tools/refinery/viatra/runtime/rete/aggregation/GroupedSet.java
@@ -0,0 +1,114 @@
+/*******************************************************************************
+ * Copyright (c) 2010-2019, Tamas Szabo, itemis AG, Gabor Bergmann, IncQuery Labs Ltd.
+ * 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.rete.aggregation;
+
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.Set;
+import java.util.function.BiFunction;
+
+/**
+ * An optimized {@link Set} implementation where each contained value is produced by combining together a grouping value
+ * and some other (key) object. The way of combining together these two values is specified by the closure passed to the
+ * constructor. Only a select few {@link Set} operations are supported. This collection is unmodifiable.
+ * 
+ * @author Tamas Szabo
+ * @since 2.4
+ */
+public class GroupedSet<GroupingValueType, GroupedKeyType, WholeKeyType> implements Set<WholeKeyType> {
+
+    protected final GroupingValueType group;
+    protected final Collection<GroupedKeyType> values;
+    protected final BiFunction<GroupingValueType, GroupedKeyType, WholeKeyType> valueFunc;
+
+    public GroupedSet(final GroupingValueType group, final Collection<GroupedKeyType> values,
+            final BiFunction<GroupingValueType, GroupedKeyType, WholeKeyType> valueFunc) {
+        this.group = group;
+        this.values = values;
+        this.valueFunc = valueFunc;
+    }
+
+    @Override
+    public int size() {
+        return this.values.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return this.values.isEmpty();
+    }
+
+    @Override
+    public boolean contains(final Object obj) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Iterator<WholeKeyType> iterator() {
+        final Iterator<GroupedKeyType> wrapped = this.values.iterator();
+        return new Iterator<WholeKeyType>() {
+            @Override
+            public boolean hasNext() {
+                return wrapped.hasNext();
+            }
+
+            @Override
+            public WholeKeyType next() {
+                final GroupedKeyType value = wrapped.next();
+                return valueFunc.apply(group, value);
+            }
+        };
+    }
+
+    @Override
+    public Object[] toArray() {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public <T> T[] toArray(final T[] arr) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean add(final WholeKeyType tuple) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean remove(final Object obj) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean containsAll(final Collection<?> c) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean addAll(final Collection<? extends WholeKeyType> coll) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean retainAll(final Collection<?> coll) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean removeAll(final Collection<?> coll) {
+        throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void clear() {
+        throw new UnsupportedOperationException();
+    }
+
+}
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