1 files changed, 94 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
new file mode 100644
index 00000000000..f7d72ade20d
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/data/access/helpers/MatchFeatureData.java
@@ -0,0 +1,94 @@
+// 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 com.yahoo.data.access.ArrayTraverser;
+import com.yahoo.data.access.Inspector;
+import com.yahoo.data.access.ObjectTraverser;
+import com.yahoo.data.access.Type;
+import com.yahoo.data.access.simple.Value;
+
+import java.util.ArrayList;
+import java.util.AbstractMap.SimpleEntry;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * MatchFeatureData helps pack match features for hits into
+ * inspectable HitValue objects, all sharing the same Hashlet
+ * for the field names.
+ * @author arnej
+ */
+public class MatchFeatureData {
+
+    private final Hashlet<String,Integer> hashlet;
+
+    public MatchFeatureData(List<String> keys) {
+        this.hashlet = new Hashlet<>();
+        hashlet.reserve(keys.size());
+        int i = 0;
+        for (String key : keys) {
+            hashlet.put(key, i++);
+        }
+    }
+
+    public static class HitValue extends Value {
+        private final Hashlet<String,Integer> hashlet;
+        private final byte[][] dataValues;
+        private final double[] doubleValues;
+
+        public Type type() { return Type.OBJECT; }
+        public boolean valid() { return true; }
+        public int fieldCount() { return hashlet.size(); }
+        public void traverse(ObjectTraverser ot) {
+            for (int i = 0; i < hashlet.size(); i++) {
+                String fn = hashlet.key(i);
+                int offset = hashlet.value(i);
+                ot.field(fn, valueAt(offset));
+            }
+        }
+        public Inspector field(String name) {
+            int offset = hashlet.getIndexOfKey(name);
+            if (offset < 0) {
+                return invalid();
+            }
+            return valueAt(offset);
+        }
+        public Iterable<Map.Entry<String,Inspector>> fields() {
+            var list = new ArrayList<Map.Entry<String,Inspector>>(hashlet.size());
+            for (int i = 0; i < hashlet.size(); i++) {
+                String fn = hashlet.key(i);
+                int offset = hashlet.value(i);
+                list.add(new SimpleEntry<String,Inspector>(fn, valueAt(offset)));
+            }
+            return list;
+        }
+
+        // use from enclosing class only
+        private HitValue(Hashlet<String,Integer> hashlet) {
+            this.hashlet = hashlet;
+            this.dataValues = new byte[hashlet.size()][];
+            this.doubleValues = new double[hashlet.size()];
+        }
+
+        public void set(int index, byte[] data) {
+            dataValues[index] = data;
+        }
+        public void set(int index, double value) {
+            doubleValues[index] = value;
+        }
+
+        private Inspector valueAt(int index) {
+            if (dataValues[index] != null) {
+                return new Value.DataValue(dataValues[index]);
+            }
+            return new Value.DoubleValue(doubleValues[index]);
+        }
+    }
+
+    public HitValue addHit() {
+        return new HitValue(hashlet);
+    }
+    
+}