feat: add UniqueByComparator

slice/slice.go

@@ -808,6 +808,30 @@ func UniqueBy[T any, U comparable](slice []T, iteratee func(item T) U) []T {
 	return result
 }
 
+// UniqueByComparator removes duplicate elements from the input slice using the provided comparator function.
+// The function maintains the order of the elements.
+// Play: todo
+func UniqueByComparator[T comparable](slice []T, comparator func(item T, other T) bool) []T {
+	result := make([]T, 0, len(slice))
+	seen := make([]T, 0, len(slice))
+
+	for _, item := range slice {
+		duplicate := false
+		for _, seenItem := range seen {
+			if comparator(item, seenItem) {
+				duplicate = true
+				break
+			}
+		}
+		if !duplicate {
+			seen = append(seen, item)
+			result = append(result, item)
+		}
+	}
+
+	return result
+}
+
 // UniqueByField remove duplicate elements in struct slice by struct field.
 // Play: https://go.dev/play/p/6cifcZSPIGu
 func UniqueByField[T any](slice []T, field string) ([]T, error) {

slice/slice_example_test.go

@@ -5,6 +5,7 @@ import (
 	"math"
 	"reflect"
 	"strconv"
+	"strings"
 )
 
 func ExampleContain() {
@@ -780,6 +781,23 @@ func ExampleUniqueBy() {
 	// [1 2 3]
 }
 
+func ExampleUniqueByComparator() {
+	uniqueNums := UniqueByComparator([]int{1, 2, 3, 1, 2, 4, 5, 6, 4}, func(item int, other int) bool {
+		return item == other
+	})
+
+	caseInsensitiveStrings := UniqueByComparator([]string{"apple", "banana", "Apple", "cherry", "Banana", "date"}, func(item string, other string) bool {
+		return strings.ToLower(item) == strings.ToLower(other)
+	})
+
+	fmt.Println(uniqueNums)
+	fmt.Println(caseInsensitiveStrings)
+
+	// Output:
+	// [1 2 3 4 5 6]
+	// [apple banana cherry date]
+}
+
 func ExampleUniqueByField() {
 	type User struct {
 		ID   int    `json:"id"`

slice/slice_test.go

@@ -5,6 +5,7 @@ import (
 	"math"
 	"reflect"
 	"strconv"
+	"strings"
 	"testing"
 
 	"github.com/duke-git/lancet/v2/internal"
@@ -764,6 +765,58 @@ func TestUniqueByField(t *testing.T) {
 	}, uniqueUsers)
 }
 
+func TestUniqueByComparator(t *testing.T) {
+	t.Parallel()
+
+	assert := internal.NewAssert(t, "TestUniqueByComparator")
+
+	t.Run("equal comparison", func(t *testing.T) {
+		nums := []int{1, 2, 3, 1, 2, 4, 5, 6, 4, 7}
+		comparator := func(item int, other int) bool {
+			return item == other
+		}
+		result := UniqueByComparator(nums, comparator)
+
+		assert.Equal([]int{1, 2, 3, 4, 5, 6, 7}, result)
+	})
+
+	t.Run("unique struct slice by field", func(t *testing.T) {
+		type student struct {
+			Name string
+			Age  int
+		}
+
+		students := []student{
+			{Name: "a", Age: 11},
+			{Name: "b", Age: 12},
+			{Name: "a", Age: 13},
+			{Name: "c", Age: 14},
+		}
+
+		comparator := func(item, other student) bool { return item.Name == other.Name }
+
+		result := UniqueByComparator(students, comparator)
+
+		assert.Equal([]student{
+			{Name: "a", Age: 11},
+			{Name: "b", Age: 12},
+			{Name: "c", Age: 14},
+		}, result)
+	})
+
+	t.Run("case-insensitive string comparison", func(t *testing.T) {
+		stringSlice := []string{"apple", "banana", "Apple", "cherry", "Banana", "date"}
+		caseInsensitiveComparator := func(item, other string) bool {
+			return strings.ToLower(item) == strings.ToLower(other)
+		}
+
+		result := UniqueByComparator(stringSlice, caseInsensitiveComparator)
+
+		assert.Equal([]string{"apple", "banana", "cherry", "date"}, result)
+	})
+
+}
+
 func TestUnion(t *testing.T) {
 	t.Parallel()