[lucene] 01/01: LUCENE-10022: Rewrite empty DisjunctionMaxQuery to MatchNoDocsQuery

[ju...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

julietibs pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/lucene.git

commit 08e61a22016233fa68caa92f850657a2494bd3a2
Author: Julie Tibshirani <ju...@gmail.com>
AuthorDate: Thu Jul 8 19:08:33 2021 -0700

    LUCENE-10022: Rewrite empty DisjunctionMaxQuery to MatchNoDocsQuery
    
    It's possible to create a DisjunctionMaxQuery with no clauses. This is now
    rewritten to MatchNoDocsQuery, matching the approach we take for BooleanQuery.
---
 lucene/CHANGES.txt                                                | 3 +++
 .../src/java/org/apache/lucene/search/DisjunctionMaxQuery.java    | 4 ++++
 .../test/org/apache/lucene/search/TestDisjunctionMaxQuery.java    | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index f113085..c55f399 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -379,6 +379,9 @@ Optimizations
   particular in the case of many fields and many indexing threads.
   (Adrien Grand)
 
+* LUCENE-10022: Rewrite empty DisjunctionMaxQuery to MatchNoDocsQuery.
+  (David Harsha via Julie Tibshirani)
+
 Bug Fixes
 ---------------------
 * LUCENE-9988: Fix DrillSideways correctness bug introduced in LUCENE-9944 (Greg Miller)
diff --git a/lucene/core/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java b/lucene/core/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
index 3b2e1e2..2ca6576 100644
--- a/lucene/core/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
+++ b/lucene/core/src/java/org/apache/lucene/search/DisjunctionMaxQuery.java
@@ -207,6 +207,10 @@ public final class DisjunctionMaxQuery extends Query implements Iterable<Query>
    */
   @Override
   public Query rewrite(IndexReader reader) throws IOException {
+    if (disjuncts.isEmpty()) {
+      return new MatchNoDocsQuery("empty DisjunctionMaxQuery");
+    }
+
     if (disjuncts.size() == 1) {
       return disjuncts.iterator().next();
     }
diff --git a/lucene/core/src/test/org/apache/lucene/search/TestDisjunctionMaxQuery.java b/lucene/core/src/test/org/apache/lucene/search/TestDisjunctionMaxQuery.java
index f55b3a5..e381826 100644
--- a/lucene/core/src/test/org/apache/lucene/search/TestDisjunctionMaxQuery.java
+++ b/lucene/core/src/test/org/apache/lucene/search/TestDisjunctionMaxQuery.java
@@ -22,6 +22,7 @@ import java.text.DecimalFormat;
 import java.text.DecimalFormatSymbols;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import org.apache.lucene.analysis.MockAnalyzer;
@@ -468,6 +469,13 @@ public class TestDisjunctionMaxQuery extends LuceneTestCase {
     assertEquals(expected, rewritten);
   }
 
+  public void testRewriteEmpty() throws Exception {
+    DisjunctionMaxQuery q = new DisjunctionMaxQuery(Collections.emptyList(), 0.0f);
+    Query rewritten = s.rewrite(q);
+    Query expected = new MatchNoDocsQuery();
+    assertEquals(expected, rewritten);
+  }
+
   public void testDisjunctOrderAndEquals() throws Exception {
     // the order that disjuncts are provided in should not matter for equals() comparisons
     Query sub1 = tq("hed", "albino");