add filtering to hide implicitly added match features

2 files changed, 51 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureData.java b/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureData.java
index f7d72ade20d..4f8bd64f85a 100644
--- a/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureData.java
+++ b/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureData.java
@@ -13,6 +13,7 @@ import java.util.ArrayList;
 import java.util.AbstractMap.SimpleEntry;
 import java.util.List;
 import java.util.Map;
+import java.util.function.Function;
 
 /**
  * MatchFeatureData helps pack match features for hits into
@@ -85,6 +86,16 @@ public class MatchFeatureData {
             }
             return new Value.DoubleValue(doubleValues[index]);
         }
+
+        public HitValue subsetFilter(Function<Hashlet<String,Integer>, Hashlet<String,Integer>> filter) {
+            return new HitValue(filter.apply(hashlet), dataValues, doubleValues);
+        }
+        // used only from subsetFilter() above
+        private HitValue(Hashlet<String,Integer> hashlet, byte[][] dataValues, double[] doubleValues) {
+            this.hashlet = hashlet;
+            this.dataValues = dataValues;
+            this.doubleValues = doubleValues;
+        }
     }
 
     public HitValue addHit() {
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
--- /dev/null
+++ 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));
+    }
+
+}