Merge pull request #1346 from ydb-platform/xslices

added xslices.Map and xslices.Filter

Author: asmyasnikov

internal/xslices/map.go

@@ -0,0 +1,11 @@
+package xslices
+
+func Map[Key comparable, T any](x []T, key func(t T) Key) map[Key]T {
+	m := make(map[Key]T, len(x))
+
+	for i := range x {
+		m[key(x[i])] = x[i]
+	}
+
+	return m
+}

internal/xslices/map_test.go

@@ -0,0 +1,19 @@
+package xslices
+
+import (
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMap(t *testing.T) {
+	require.Equal(t,
+		map[string]int{
+			"1": 1,
+			"2": 2,
+			"3": 3,
+		},
+		Map([]int{1, 2, 3}, strconv.Itoa),
+	)
+}

internal/xslices/split.go

@@ -0,0 +1,16 @@
+package xslices
+
+func Filter[T any](x []T, filter func(t T) bool) (good, bad []T) {
+	good = make([]T, 0, len(x))
+	bad = make([]T, 0, len(x))
+
+	for i := 0; i < len(x); i++ {
+		if filter(x[i]) {
+			good = append(good, x[i])
+		} else {
+			bad = append(bad, x[i])
+		}
+	}
+
+	return good, bad
+}

internal/xslices/split_test.go

@@ -0,0 +1,15 @@
+package xslices
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFilter(t *testing.T) {
+	good, bad := Filter([]int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, func(t int) bool {
+		return t%2 == 0
+	})
+	require.Equal(t, []int{0, 2, 4, 6, 8}, good)
+	require.Equal(t, []int{1, 3, 5, 7, 9}, bad)
+}