1 files changed, 40 insertions, 0 deletions
diff --git a/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureFilter.java b/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureFilter.java
new file mode 100644
index 00000000000..96451f35504
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+++ b/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureFilter.java
@@ -0,0 +1,40 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.data.access.helpers;
+
+import com.yahoo.collections.Hashlet;
+
+import java.util.Collection;
+import java.util.IdentityHashMap;
+import java.util.function.Function;
+
+/**
+ *  Helper class to remove (filter) some names from a Hashlet
+ *  @author arnej
+ */
+public class MatchFeatureFilter implements Function<Hashlet<String,Integer>, Hashlet<String,Integer>> {
+
+    private final IdentityHashMap<Hashlet<String,Integer>, Hashlet<String,Integer>> mappings = new IdentityHashMap<>();
+    private final Collection<String> removeList;
+
+    public MatchFeatureFilter(Collection<String> removeList) {
+        this.removeList = removeList;
+    }
+
+    Hashlet<String,Integer> filter(Hashlet<String,Integer> input) {
+        Hashlet<String,Integer> result = new Hashlet<>();
+        result.reserve(input.size());
+        for (int i = 0; i < input.size(); i++) {
+            String k = input.key(i);
+            if (! removeList.contains(k)) {
+                Integer v = input.value(i);
+                result.put(k, v);
+            }
+        }
+        return result;
+    }
+
+    public Hashlet<String,Integer> apply(Hashlet<String,Integer> input) {
+        return mappings.computeIfAbsent(input, k -> filter(k));
+    }
+
+}