From 8b7f42eabc6d10e7e566fdd054cf1e05b90fba76 Mon Sep 17 00:00:00 2001
From: Alex Klibisz <8015228+alexklibisz@users.noreply.github.com>
Date: Sun, 26 Nov 2023 21:31:41 -0800
Subject: [PATCH] Refactor: Add EmptyHitCounter for use in
 MatchHashesAndScoreQuerySuite (#601)

---
 .../elastiknn/search/EmptyHitCounter.java     | 46 +++++++++++++++++++
 .../search/MatchHashesAndScoreQuery.java      |  3 +-
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 elastiknn-lucene/src/main/java/com/klibisz/elastiknn/search/EmptyHitCounter.java

diff --git a/elastiknn-lucene/src/main/java/com/klibisz/elastiknn/search/EmptyHitCounter.java b/elastiknn-lucene/src/main/java/com/klibisz/elastiknn/search/EmptyHitCounter.java
new file mode 100644
index 000000000..d4160887e
--- /dev/null
+++ b/elastiknn-lucene/src/main/java/com/klibisz/elastiknn/search/EmptyHitCounter.java
@@ -0,0 +1,46 @@
+package com.klibisz.elastiknn.search;
+
+import org.apache.lucene.search.KthGreatest;
+
+public final class EmptyHitCounter implements HitCounter {
+    @Override
+    public void increment(int key, short count) {}
+
+    @Override
+    public void increment(int key, int count) {}
+
+    @Override
+    public boolean isEmpty() {
+        return true;
+    }
+
+    @Override
+    public short get(int key) {
+        return 0;
+    }
+
+    @Override
+    public int numHits() {
+        return 0;
+    }
+
+    @Override
+    public int capacity() {
+        return 0;
+    }
+
+    @Override
+    public int minKey() {
+        return 0;
+    }
+
+    @Override
+    public int maxKey() {
+        return 0;
+    }
+
+    @Override
+    public KthGreatest.Result kthGreatest(int k) {
+        return new KthGreatest.Result((short) 0, 0, 0);
+    }
+}
diff --git a/elastiknn-lucene/src/main/java/org/apache/lucene/search/MatchHashesAndScoreQuery.java b/elastiknn-lucene/src/main/java/org/apache/lucene/search/MatchHashesAndScoreQuery.java
index 5132f10d0..4962ca253 100644
--- a/elastiknn-lucene/src/main/java/org/apache/lucene/search/MatchHashesAndScoreQuery.java
+++ b/elastiknn-lucene/src/main/java/org/apache/lucene/search/MatchHashesAndScoreQuery.java
@@ -2,6 +2,7 @@
 
 import com.klibisz.elastiknn.models.HashAndFreq;
 import com.klibisz.elastiknn.search.ArrayHitCounter;
+import com.klibisz.elastiknn.search.EmptyHitCounter;
 import com.klibisz.elastiknn.search.HitCounter;
 import org.apache.lucene.index.*;
 import org.apache.lucene.util.BytesRef;
@@ -58,7 +59,7 @@ private HitCounter countHits(LeafReader reader) throws IOException {
                 Terms terms = reader.terms(field);
                 // terms seem to be null after deleting docs. https://github.com/alexklibisz/elastiknn/issues/158
                 if (terms == null) {
-                    return new ArrayHitCounter(0);
+                    return new EmptyHitCounter();
                 } else {
                     TermsEnum termsEnum = terms.iterator();
                     PostingsEnum docs = null;