From 2d7945696c9bdbac8cf3f850141d70adf11cc8d9 Mon Sep 17 00:00:00 2001
From: Tulir Asokan <tulir@maunium.net>
Date: Mon, 22 Jul 2024 11:57:53 +0300
Subject: [PATCH] exslices: add utility to deduplicate unsorted list

---
 exslices/deduplicate.go | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 exslices/deduplicate.go

diff --git a/exslices/deduplicate.go b/exslices/deduplicate.go
new file mode 100644
index 0000000..1226c73
--- /dev/null
+++ b/exslices/deduplicate.go
@@ -0,0 +1,23 @@
+// Copyright (c) 2024 Tulir Asokan
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package exslices
+
+// DeduplicateUnsorted removes duplicates from the given slice without requiring that the input slice is sorted.
+// The order of the output will be the same as the input.
+//
+// If you don't care about the order of the output, it's recommended to sort the list and then use [slices.Compact].
+func DeduplicateUnsorted[T comparable](s []T) []T {
+	seen := make(map[T]struct{}, len(s))
+	result := make([]T, 0, len(s))
+	for _, item := range s {
+		if _, ok := seen[item]; !ok {
+			seen[item] = struct{}{}
+			result = append(result, item)
+		}
+	}
+	return result
+}