From e14327288e61dacd278b748f332d907758c07b26 Mon Sep 17 00:00:00 2001
From: Erik Pellizzon <erikpellizzon@gmail.com>
Date: Fri, 6 Jan 2023 23:35:52 +0100
Subject: [PATCH] Documenting that IndexReaderContext#leaves() will never
 return a null value and remove the null checks from the method calls (#12034)

---
 lucene/CHANGES.txt                                        | 2 ++
 .../java/org/apache/lucene/index/IndexReaderContext.java  | 3 ++-
 .../core/src/java/org/apache/lucene/index/TermStates.java | 8 +-------
 .../java/org/apache/lucene/search/BlendedTermQuery.java   | 8 +-------
 4 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 48f7189e102..6017ca66652 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -197,6 +197,8 @@ Improvements
 
 * GITHUB#12016: Upgrade lucene/expressions to use antlr 4.11.1 (Andriy Redko)
 
+* GITHUB#12034: Remove null check in IndexReaderContext#leaves() usages (Erik Pellizzon)
+
 Bug Fixes
 ---------------------
 * GITHUB#11726: Indexing term vectors on large documents could fail due to
diff --git a/lucene/core/src/java/org/apache/lucene/index/IndexReaderContext.java b/lucene/core/src/java/org/apache/lucene/index/IndexReaderContext.java
index f39c2746cab..fbc59e3d1ca 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexReaderContext.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexReaderContext.java
@@ -64,7 +64,8 @@ public abstract class IndexReaderContext {
 
   /**
    * Returns the context's leaves if this context is a top-level context. For convenience, if this
-   * is an {@link LeafReaderContext} this returns itself as the only leaf.
+   * is an {@link LeafReaderContext} this returns itself as the only leaf, and it will never return
+   * a null value.
    *
    * <p>Note: this is convenience method since leaves can always be obtained by walking the context
    * tree using {@link #children()}.
diff --git a/lucene/core/src/java/org/apache/lucene/index/TermStates.java b/lucene/core/src/java/org/apache/lucene/index/TermStates.java
index d1c10401190..bf4b97e86e5 100644
--- a/lucene/core/src/java/org/apache/lucene/index/TermStates.java
+++ b/lucene/core/src/java/org/apache/lucene/index/TermStates.java
@@ -49,13 +49,7 @@ public final class TermStates {
     topReaderContextIdentity = context.identity;
     docFreq = 0;
     totalTermFreq = 0;
-    final int len;
-    if (context.leaves() == null) {
-      len = 1;
-    } else {
-      len = context.leaves().size();
-    }
-    states = new TermState[len];
+    states = new TermState[context.leaves().size()];
     this.term = term;
   }
 
diff --git a/lucene/core/src/java/org/apache/lucene/search/BlendedTermQuery.java b/lucene/core/src/java/org/apache/lucene/search/BlendedTermQuery.java
index 507b4911ae6..2c7e41ac971 100644
--- a/lucene/core/src/java/org/apache/lucene/search/BlendedTermQuery.java
+++ b/lucene/core/src/java/org/apache/lucene/search/BlendedTermQuery.java
@@ -314,14 +314,8 @@ public final class BlendedTermQuery extends Query {
       IndexReaderContext readerContext, TermStates ctx, int artificialDf, long artificialTtf)
       throws IOException {
     List<LeafReaderContext> leaves = readerContext.leaves();
-    final int len;
-    if (leaves == null) {
-      len = 1;
-    } else {
-      len = leaves.size();
-    }
     TermStates newCtx = new TermStates(readerContext);
-    for (int i = 0; i < len; ++i) {
+    for (int i = 0; i < leaves.size(); ++i) {
       TermState termState = ctx.get(leaves.get(i));
       if (termState == null) {
         continue;