From 976501f6f3fe602ada85a6f2392d1bb23438a319 Mon Sep 17 00:00:00 2001
From: Alan Woodward <romseygeek@apache.org>
Date: Wed, 29 Jun 2016 10:36:28 +0100
Subject: [PATCH] LUCENE-7359: Add equals() and hashCode() to Explanation

---
 lucene/CHANGES.txt                            |  2 ++
 .../org/apache/lucene/search/Explanation.java | 19 ++++++++++--
 .../lucene/search/TestSimpleExplanations.java | 29 +++++++++++++++++++
 3 files changed, 48 insertions(+), 2 deletions(-)

diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 912e601750f..53e18a566c8 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -56,6 +56,8 @@ Improvements
   and empty boolean queries now rewrite to MatchNoDocsQuery instead of
   vice/versa (Jim Ferenczi via Mike McCandless)
 
+* LUCENE-7359: Add equals() and hashCode() to Explanation (Alan Woodward)
+
 Optimizations
 
 * LUCENE-7330, LUCENE-7339: Speed up conjunction queries. (Adrien Grand)
diff --git a/lucene/core/src/java/org/apache/lucene/search/Explanation.java b/lucene/core/src/java/org/apache/lucene/search/Explanation.java
index 3e5951a5a0f..6af1019bdf8 100644
--- a/lucene/core/src/java/org/apache/lucene/search/Explanation.java
+++ b/lucene/core/src/java/org/apache/lucene/search/Explanation.java
@@ -16,7 +16,6 @@
  */
 package org.apache.lucene.search;
 
-
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -121,7 +120,6 @@ public final class Explanation {
     return buffer.toString();
   }
 
-
   /** Render an explanation as HTML. */
   @Deprecated
   public String toHtml() {
@@ -142,4 +140,21 @@ public final class Explanation {
 
     return buffer.toString();
   }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+    Explanation that = (Explanation) o;
+    return match == that.match &&
+        Float.compare(that.value, value) == 0 &&
+        Objects.equals(description, that.description) &&
+        Objects.equals(details, that.details);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(match, value, description, details);
+  }
+
 }
diff --git a/lucene/core/src/test/org/apache/lucene/search/TestSimpleExplanations.java b/lucene/core/src/test/org/apache/lucene/search/TestSimpleExplanations.java
index 422245a8a49..9f8c589499d 100644
--- a/lucene/core/src/test/org/apache/lucene/search/TestSimpleExplanations.java
+++ b/lucene/core/src/test/org/apache/lucene/search/TestSimpleExplanations.java
@@ -20,6 +20,7 @@ package org.apache.lucene.search;
 import java.util.Arrays;
 
 import org.apache.lucene.index.Term;
+import org.junit.Test;
 
 /**
  * TestExplanations subclass focusing on basic query types
@@ -715,4 +716,32 @@ public class TestSimpleExplanations extends BaseExplanationTestCase {
     qtest(query, new int[] { 0,1,2,3 });
   }
 
+  @Test
+  public void testEquality() {
+
+    Explanation e1 = Explanation.match(1f, "an explanation");
+    Explanation e2 = Explanation.match(1f, "an explanation", Explanation.match(1f, "a subexplanation"));
+    Explanation e25 = Explanation.match(1f, "an explanation",
+        Explanation.match(1f, "a subexplanation", Explanation.match(1f, "a subsubexplanation")));
+    Explanation e3 = Explanation.match(1f, "an explanation");
+    Explanation e4 = Explanation.match(2f, "an explanation");
+    Explanation e5 = Explanation.noMatch("an explanation");
+    Explanation e6 = Explanation.noMatch("an explanation", Explanation.match(1f, "a subexplanation"));
+    Explanation e7 = Explanation.noMatch("an explanation");
+    Explanation e8 = Explanation.match(1f, "another explanation");
+
+    assertEquals(e1, e3);
+    assertFalse(e1.equals(e2));
+    assertFalse(e2.equals(e25));
+    assertFalse(e1.equals(e4));
+    assertFalse(e1.equals(e5));
+    assertEquals(e5, e7);
+    assertFalse(e5.equals(e6));
+    assertFalse(e1.equals(e8));
+
+    assertEquals(e1.hashCode(), e3.hashCode());
+    assertEquals(e5.hashCode(), e7.hashCode());
+
+  }
+
 }