feat: add Entries FromEntries Transform

maputil/map.go

@@ -4,7 +4,11 @@
 // Package maputil includes some functions to manipulate map.
 package maputil
 
-import "reflect"
+import (
+	"reflect"
+
+	"github.com/duke-git/lancet/v2/slice"
+)
 
 // Keys returns a slice of the map's keys.
 // Play: https://go.dev/play/p/xNB5bTb97Wd
@@ -34,6 +38,30 @@ func Values[K comparable, V any](m map[K]V) []V {
 	return values
 }
 
+// KeysBy creates a slice whose element is the result of function mapper invoked by every map's key.
+// Play: todo
+func KeysBy[K comparable, V any, T any](m map[K]V, mapper func(item K) T) []T {
+	keys := make([]T, 0, len(m))
+
+	for k := range m {
+		keys = append(keys, mapper(k))
+	}
+
+	return keys
+}
+
+// ValuesBy creates a slice whose element is the result of function mapper invoked by every map's value.
+// Play: todo
+func ValuesBy[K comparable, V any, T any](m map[K]V, mapper func(item V) T) []T {
+	keys := make([]T, 0, len(m))
+
+	for _, v := range m {
+		keys = append(keys, mapper(v))
+	}
+
+	return keys
+}
+
 // Merge maps, next key will overwrite previous key.
 // Play: https://go.dev/play/p/H95LENF1uB-
 func Merge[K comparable, V any](maps ...map[K]V) map[K]V {
@@ -69,6 +97,32 @@ func Filter[K comparable, V any](m map[K]V, predicate func(key K, value V) bool)
 	return result
 }
 
+// FilterByKeys iterates over map, return a new map whose keys are all given keys.
+// Play: todo
+func FilterByKeys[K comparable, V any](m map[K]V, keys []K) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if slice.Contain(keys, k) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
+// FilterByValues iterates over map, return a new map whose values are all given values.
+// Play: todo
+func FilterByValues[K comparable, V comparable](m map[K]V, values []V) map[K]V {
+	result := make(map[K]V)
+
+	for k, v := range m {
+		if slice.Contain(values, v) {
+			result[k] = v
+		}
+	}
+	return result
+}
+
 // Intersect iterates over maps, return a new map of key and value pairs in all given maps.
 // Play: https://go.dev/play/p/Zld0oj3sjcC
 func Intersect[K comparable, V any](maps ...map[K]V) map[K]V {
@@ -126,3 +180,49 @@ func IsDisjoint[K comparable, V any](mapA, mapB map[K]V) bool {
 	}
 	return true
 }
+
+// Entry is a key/value pairs.
+type Entry[K comparable, V any] struct {
+	Key   K
+	Value V
+}
+
+// Entries transforms a map into array of key/value pairs.
+// Play: todo
+func Entries[K comparable, V any](m map[K]V) []Entry[K, V] {
+	entries := make([]Entry[K, V], 0, len(m))
+
+	for k, v := range m {
+		entries = append(entries, Entry[K, V]{
+			Key:   k,
+			Value: v,
+		})
+	}
+
+	return entries
+}
+
+// FromEntries creates a map based on a slice of key/value pairs
+// Play: todo
+func FromEntries[K comparable, V any](entries []Entry[K, V]) map[K]V {
+	result := make(map[K]V, len(entries))
+
+	for _, v := range entries {
+		result[v.Key] = v.Value
+	}
+
+	return result
+}
+
+// Transform a map to another type map.
+// Play: todo
+func Transform[K1 comparable, V1 any, K2 comparable, V2 any](m map[K1]V1, iteratee func(key K1, value V1) (K2, V2)) map[K2]V2 {
+	result := make(map[K2]V2, len(m))
+
+	for k1, v1 := range m {
+		k2, v2 := iteratee(k1, v1)
+		result[k2] = v2
+	}
+
+	return result
+}

maputil/map_test.go

@@ -2,6 +2,7 @@ package maputil
 
 import (
 	"sort"
+	"strconv"
 	"testing"
 
 	"github.com/duke-git/lancet/v2/internal"
@@ -41,6 +42,51 @@ func TestValues(t *testing.T) {
 	assert.Equal([]string{"a", "a", "b", "c", "d"}, values)
 }
 
+func TestKeysBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestKeysBy")
+
+	m := map[int]string{
+		1: "a",
+		2: "a",
+		3: "b",
+	}
+
+	keys := KeysBy(m, func(n int) int {
+		return n + 1
+	})
+
+	sort.Ints(keys)
+
+	assert.Equal([]int{2, 3, 4}, keys)
+}
+
+func TestValuesBy(t *testing.T) {
+	assert := internal.NewAssert(t, "TestValuesBy")
+
+	m := map[int]string{
+		1: "a",
+		2: "b",
+		3: "c",
+	}
+
+	values := ValuesBy(m, func(v string) string {
+		switch v {
+		case "a":
+			return "a-1"
+		case "b":
+			return "b-2"
+		case "c":
+			return "c-3"
+		default:
+			return ""
+		}
+	})
+
+	sort.Strings(values)
+
+	assert.Equal([]string{"a-1", "b-2", "c-3"}, values)
+}
+
 func TestMerge(t *testing.T) {
 	assert := internal.NewAssert(t, "TestMerge")
 
@@ -104,6 +150,44 @@ func TestFilter(t *testing.T) {
 	}, acturl)
 }
 
+func TestFilterByKeys(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterByKeys")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	acturl := FilterByKeys(m, []string{"a", "b"})
+
+	assert.Equal(map[string]int{
+		"a": 1,
+		"b": 2,
+	}, acturl)
+}
+
+func TestFilterByValues(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFilterByValues")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+		"d": 4,
+		"e": 5,
+	}
+
+	acturl := FilterByValues(m, []int{3, 4})
+
+	assert.Equal(map[string]int{
+		"c": 3,
+		"d": 4,
+	}, acturl)
+}
+
 func TestIntersect(t *testing.T) {
 	assert := internal.NewAssert(t, "TestIntersect")
 
@@ -170,3 +254,60 @@ func TestIsDisjoint(t *testing.T) {
 
 	assert.Equal(false, IsDisjoint(m1, m3))
 }
+
+func TestEntries(t *testing.T) {
+	assert := internal.NewAssert(t, "TestEntries")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	result := Entries(m)
+
+	sort.Slice(result, func(i, j int) bool {
+		return result[i].Value < result[j].Value
+	})
+
+	expected := []Entry[string, int]{{Key: "a", Value: 1}, {Key: "b", Value: 2}, {Key: "c", Value: 3}}
+
+	assert.Equal(expected, result)
+}
+
+func TestFromEntries(t *testing.T) {
+	assert := internal.NewAssert(t, "TestFromEntries")
+
+	result := FromEntries([]Entry[string, int]{
+		{Key: "a", Value: 1},
+		{Key: "b", Value: 2},
+		{Key: "c", Value: 3},
+	})
+
+	assert.Equal(3, len(result))
+	assert.Equal(1, result["a"])
+	assert.Equal(2, result["b"])
+	assert.Equal(3, result["c"])
+}
+
+func TestTransform(t *testing.T) {
+	assert := internal.NewAssert(t, "TestTransform")
+
+	m := map[string]int{
+		"a": 1,
+		"b": 2,
+		"c": 3,
+	}
+
+	result := Transform(m, func(k string, v int) (string, string) {
+		return k, strconv.Itoa(v)
+	})
+
+	expected := map[string]string{
+		"a": "1",
+		"b": "2",
+		"c": "3",
+	}
+
+	assert.Equal(expected, result)
+}