From 373b7ce682b2d182a75a0af262996b1299ee459b Mon Sep 17 00:00:00 2001
From: DBotThePony <dbotthepony@yandex.ru>
Date: Wed, 29 May 2024 12:33:40 +0700
Subject: [PATCH] reduce() without identity

---
 gradle.properties                                      |  2 +-
 .../ru/dbotthepony/kommons/collect/StreamyIterators.kt | 10 ++++++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/gradle.properties b/gradle.properties
index e427997..22c9bfc 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -4,7 +4,7 @@ kotlin.code.style=official
 specifyKotlinAsDependency=false
 
 projectGroup=ru.dbotthepony.kommons
-projectVersion=2.18.0
+projectVersion=2.18.1
 
 guavaDepVersion=33.0.0
 gsonDepVersion=2.8.9
diff --git a/src/main/kotlin/ru/dbotthepony/kommons/collect/StreamyIterators.kt b/src/main/kotlin/ru/dbotthepony/kommons/collect/StreamyIterators.kt
index 52ce11f..2b23d14 100644
--- a/src/main/kotlin/ru/dbotthepony/kommons/collect/StreamyIterators.kt
+++ b/src/main/kotlin/ru/dbotthepony/kommons/collect/StreamyIterators.kt
@@ -1,5 +1,6 @@
 package ru.dbotthepony.kommons.collect
 
+import ru.dbotthepony.kommons.util.KOptional
 import java.util.*
 import java.util.function.Predicate
 import java.util.stream.Collector
@@ -218,6 +219,15 @@ inline fun <T> Iterator<T>.reduce(identity: T, reducer: (T, T) -> T): T {
 	return result
 }
 
+inline fun <T> Iterator<T>.reduce(reducer: (T, T) -> T): KOptional<T> {
+	if (!hasNext())
+		return KOptional()
+
+	var result = next()
+	while (hasNext()) result = reducer.invoke(result, next())
+	return KOptional(result)
+}
+
 fun <T> Iterator<T?>.filterNotNull(): MutableIterator<T> = filter { it != null } as MutableIterator<T>
 
 inline fun <reified T> Iterator<*>.filterIsInstance(): MutableIterator<T> = filter { it is T } as MutableIterator<T>