From b79199f9be4a528101772801b28346cc174b35c7 Mon Sep 17 00:00:00 2001
From: kucherenkovova <kucherenkovova@gmail.com>
Date: Fri, 31 May 2024 20:28:08 +0300
Subject: [PATCH] [xslices] added `Unique` function (#3)

---
 go.work                |  1 +
 xslices/README.md      |  7 ++++++
 xslices/go.mod         |  3 +++
 xslices/slices.go      | 23 +++++++++++++++++++
 xslices/slices_test.go | 52 ++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 86 insertions(+)
 create mode 100644 xslices/README.md
 create mode 100644 xslices/go.mod
 create mode 100644 xslices/slices.go
 create mode 100644 xslices/slices_test.go

diff --git a/go.work b/go.work
index f56dbda..e035e45 100644
--- a/go.work
+++ b/go.work
@@ -4,6 +4,7 @@ use (
 	./xmaps
 	./xmath
 	./xnet/xhttp
+	./xslices
 	./xslog
 	./xstrconv
 )
diff --git a/xslices/README.md b/xslices/README.md
new file mode 100644
index 0000000..ca59481
--- /dev/null
+++ b/xslices/README.md
@@ -0,0 +1,7 @@
+# xslices
+Extensions to the standard Go library's `slices` package.
+
+### Install
+```
+go get github.com/kucherenkovova/gopypaste/xslices@v0.1.0
+```
\ No newline at end of file
diff --git a/xslices/go.mod b/xslices/go.mod
new file mode 100644
index 0000000..e2fc147
--- /dev/null
+++ b/xslices/go.mod
@@ -0,0 +1,3 @@
+module github.com/kucherenkovova/gopypaste/xslices
+
+go 1.22
diff --git a/xslices/slices.go b/xslices/slices.go
new file mode 100644
index 0000000..170d828
--- /dev/null
+++ b/xslices/slices.go
@@ -0,0 +1,23 @@
+package xslices
+
+// Unique returns a new slice containing only the unique elements of the input slice.
+// Only first occurrence of each element is preserved.
+func Unique[T comparable](list []T) []T {
+	if list == nil {
+		return nil
+	}
+
+	seen := make(map[T]struct{}, len(list))
+	results := make([]T, 0, len(list))
+
+	for _, element := range list {
+		if _, ok := seen[element]; ok {
+			continue
+		}
+
+		seen[element] = struct{}{}
+		results = append(results, element)
+	}
+
+	return results
+}
diff --git a/xslices/slices_test.go b/xslices/slices_test.go
new file mode 100644
index 0000000..e62b489
--- /dev/null
+++ b/xslices/slices_test.go
@@ -0,0 +1,52 @@
+package xslices_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/kucherenkovova/gopypaste/xslices"
+)
+
+func TestUnique(t *testing.T) {
+	type testCase struct {
+		name string
+		in   []string
+		want []string
+	}
+
+	tests := []testCase{
+		{
+			name: "empty list",
+			in:   []string{},
+			want: []string{},
+		},
+		{
+			name: "nil",
+			in:   nil,
+			want: nil,
+		},
+		{
+			name: "no duplicates",
+			in:   []string{"a", "b", "c"},
+			want: []string{"a", "b", "c"},
+		},
+		{
+			name: "consequent duplicates",
+			in:   []string{"a", "a", "b", "b", "c", "c"},
+			want: []string{"a", "b", "c"},
+		},
+		{
+			name: "non-consequent duplicates",
+			in:   []string{"a", "b", "a", "c", "b", "c"},
+			want: []string{"a", "b", "c"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := xslices.Unique(tt.in); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Unique() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}