1 files changed, 49 insertions, 0 deletions

diff --git a/subprojects/store-query/src/main/java/tools/refinery/store/query/view/FilteredRelationView.java b/subprojects/store-query/src/main/java/tools/refinery/store/query/view/FilteredRelationView.java
new file mode 100644
index 00000000..64c601bb
--- /dev/null
+++ b/subprojects/store-query/src/main/java/tools/refinery/store/query/view/FilteredRelationView.java
@@ -0,0 +1,49 @@
+package tools.refinery.store.query.view;
+
+import tools.refinery.store.tuple.Tuple;
+import tools.refinery.store.representation.Symbol;
+
+import java.util.Objects;
+import java.util.function.BiPredicate;
+import java.util.function.Predicate;
+
+public class FilteredRelationView<T> extends TuplePreservingRelationView<T> {
+        private final BiPredicate<Tuple, T> predicate;
+
+        public FilteredRelationView(Symbol<T> symbol, String name, BiPredicate<Tuple, T> predicate) {
+                super(symbol, name);
+                this.predicate = predicate;
+        }
+
+        public FilteredRelationView(Symbol<T> symbol, BiPredicate<Tuple, T> predicate) {
+                super(symbol);
+                this.predicate = predicate;
+        }
+
+        public FilteredRelationView(Symbol<T> symbol, String name, Predicate<T> predicate) {
+                this(symbol, name, (k, v) -> predicate.test(v));
+        }
+
+        public FilteredRelationView(Symbol<T> symbol, Predicate<T> predicate) {
+                this(symbol, (k, v) -> predicate.test(v));
+        }
+
+        @Override
+        public boolean filter(Tuple key, T value) {
+                return this.predicate.test(key, value);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+                if (this == o) return true;
+                if (o == null || getClass() != o.getClass()) return false;
+                if (!super.equals(o)) return false;
+                FilteredRelationView<?> that = (FilteredRelationView<?>) o;
+                return Objects.equals(predicate, that.predicate);
+        }
+
+        @Override
+        public int hashCode() {
+                return Objects.hash(super.hashCode(), predicate);
+        }
+}