1 files changed, 66 insertions, 0 deletions

diff --git a/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/update/RelationViewFilter.java b/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/update/RelationViewFilter.java
new file mode 100644
index 00000000..221f1b4a
--- /dev/null
+++ b/subprojects/store-query-viatra/src/main/java/tools/refinery/store/query/viatra/internal/update/RelationViewFilter.java
@@ -0,0 +1,66 @@
+package tools.refinery.store.query.viatra.internal.update;
+
+import org.eclipse.viatra.query.runtime.matchers.context.IInputKey;
+import org.eclipse.viatra.query.runtime.matchers.context.IQueryRuntimeContextListener;
+import org.eclipse.viatra.query.runtime.matchers.tuple.ITuple;
+import org.eclipse.viatra.query.runtime.matchers.tuple.Tuple;
+
+import java.util.Arrays;
+import java.util.Objects;
+
+public final class RelationViewFilter {
+        private final IInputKey inputKey;
+        private final Object[] seed;
+        private final IQueryRuntimeContextListener listener;
+
+        public RelationViewFilter(IInputKey inputKey, ITuple seed, IQueryRuntimeContextListener listener) {
+                this.inputKey = inputKey;
+                this.seed = seedToArray(seed);
+                this.listener = listener;
+        }
+
+        public void update(Tuple updateTuple, boolean isInsertion) {
+                if (isMatching(updateTuple)) {
+                        listener.update(inputKey, updateTuple, isInsertion);
+                }
+        }
+
+        private boolean isMatching(ITuple tuple) {
+                if (seed == null) {
+                        return true;
+                }
+                int size = seed.length;
+                for (int i = 0; i < size; i++) {
+                        var filterElement = seed[i];
+                        if (filterElement != null && !filterElement.equals(tuple.get(i))) {
+                                return false;
+                        }
+                }
+                return true;
+        }
+
+        // Use <code>null</code> instead of an empty array to speed up comparisons.
+        @SuppressWarnings("squid:S1168")
+        private static Object[] seedToArray(ITuple seed) {
+                for (var element : seed.getElements()) {
+                        if (element != null) {
+                                return seed.getElements();
+                        }
+                }
+                return null;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+                if (obj == this) return true;
+                if (obj == null || obj.getClass() != this.getClass()) return false;
+                var that = (RelationViewFilter) obj;
+                return Objects.equals(this.inputKey, that.inputKey) && Arrays.equals(this.seed, that.seed) &&
+                                Objects.equals(this.listener, that.listener);
+        }
+
+        @Override
+        public int hashCode() {
+                return Objects.hash(inputKey, Arrays.hashCode(seed), listener);
+        }
+}