feat: add ToMap for stream

stream/stream.go

@@ -420,3 +420,12 @@ func (s Stream[T]) LastIndexOf(target T, equal func(a, b T) bool) int {
 func (s Stream[T]) ToSlice() []T {
 	return s.source
 }
+
+func ToMap[T any, K comparable, V any](s Stream[T], mapper func(item T) (K, V)) map[K]V {
+	result := map[K]V{}
+	for _, v := range s.source {
+		k, v := mapper(v)
+		result[k] = v
+	}
+	return result
+}

stream/stream_example_test.go

@@ -412,3 +412,22 @@ func ExampleStream_LastIndexOf() {
 	// -1
 	// 3
 }
+
+func ExampleStream_ToMap() {
+	type Person struct {
+		Name string
+		Age  int
+	}
+	s := FromSlice([]Person{
+		{Name: "Tom", Age: 10},
+		{Name: "Jim", Age: 20},
+		{Name: "Mike", Age: 30},
+	})
+	m := ToMap(s, func(p Person) (string, Person) {
+		return p.Name, p
+	})
+	fmt.Println(m)
+
+	// Output:
+	// map[Jim:{Jim 20} Mike:{Mike 30} Tom:{Tom 10}]
+}

stream/stream_test.go

@@ -400,3 +400,26 @@ func TestStream_LastIndexOf(t *testing.T) {
 	assert.Equal(-1, s.LastIndexOf(0, func(a, b int) bool { return a == b }))
 	assert.Equal(4, s.LastIndexOf(2, func(a, b int) bool { return a == b }))
 }
+
+func TestStream_ToMap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_ToMap")
+	type Person struct {
+		Name string
+		Age  int
+	}
+	s := FromSlice([]Person{
+		{Name: "Tom", Age: 10},
+		{Name: "Jim", Age: 20},
+		{Name: "Mike", Age: 30},
+	})
+	m := ToMap(s, func(p Person) (string, Person) {
+		return p.Name, p
+	})
+	expected := map[string]Person{
+		"Tom":  {Name: "Tom", Age: 10},
+		"Jim":  {Name: "Jim", Age: 20},
+		"Mike": {Name: "Mike", Age: 30},
+	}
+	assert.EqualValues(expected, m)
+
+}