From a75090d1d49c5b6b2055336d2a990cc01be85712 Mon Sep 17 00:00:00 2001
From: James Baker <jbaker@palantir.com>
Date: Tue, 3 Jan 2023 11:05:10 +0000
Subject: [PATCH] Faster LinkedHashSet head() (#2728)

While writing up #2727 I noticed that `LinkedHashSet.head()` is implemented
`iterator().head()`. This is inefficient because `queue.iterator().next()`
makes a call to `.head()`, but also to `.tail()` so as to prepare for the
next `head()` call. Given the structure of the underlying `Queue`, the
`head()` call is worst case `O(1)` but the tail call is worst case
`O(n)`. The present worst case will be achieved if there have never been
overwrites or removals from the set, which is probably a fairly common
case.
---
 vavr/src/main/java/io/vavr/collection/LinkedHashSet.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/vavr/src/main/java/io/vavr/collection/LinkedHashSet.java b/vavr/src/main/java/io/vavr/collection/LinkedHashSet.java
index d6bfc505b..865bc5d98 100644
--- a/vavr/src/main/java/io/vavr/collection/LinkedHashSet.java
+++ b/vavr/src/main/java/io/vavr/collection/LinkedHashSet.java
@@ -641,12 +641,12 @@ public T head() {
         if (map.isEmpty()) {
             throw new NoSuchElementException("head of empty set");
         }
-        return iterator().next();
+        return map.head()._1();
     }
 
     @Override
     public Option<T> headOption() {
-        return iterator().headOption();
+        return map.headOption().map(Tuple2::_1);
     }
 
     @Override