From d9d3e3fb05150de6b22fc580bc458e9e6feffc35 Mon Sep 17 00:00:00 2001
From: Samuel Berthe <dev@samuel-berthe.fr>
Date: Sun, 11 Aug 2024 18:28:42 +0200
Subject: [PATCH] feat: preallocate output for lo.Keys and lo.Values

---
 map.go | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/map.go b/map.go
index 7d53b94e..27b00752 100644
--- a/map.go
+++ b/map.go
@@ -3,7 +3,11 @@ package lo
 // Keys creates an array of the map keys.
 // Play: https://go.dev/play/p/Uu11fHASqrU
 func Keys[K comparable, V any](in ...map[K]V) []K {
-	result := make([]K, 0)
+	size := 0
+	for i := range in {
+		size += len(in[i])
+	}
+	result := make([]K, 0, size)
 
 	for i := range in {
 		for k := range in[i] {
@@ -43,7 +47,11 @@ func HasKey[K comparable, V any](in map[K]V, key K) bool {
 // Values creates an array of the map values.
 // Play: https://go.dev/play/p/nnRTQkzQfF6
 func Values[K comparable, V any](in ...map[K]V) []V {
-	result := make([]V, 0, len(in))
+	size := 0
+	for i := range in {
+		size += len(in[i])
+	}
+	result := make([]V, 0, size)
 
 	for i := range in {
 		for k := range in[i] {