feat: add Max, Min for stream

stream/stream.go

@@ -10,6 +10,7 @@ import (
 	"bytes"
 	"encoding/gob"
 
+	"github.com/duke-git/lancet/v2/slice"
 	"golang.org/x/exp/constraints"
 )
 
@@ -23,7 +24,7 @@ import (
 // 	Map(mapper func(item T) T) StreamI[T]
 // 	Peek(consumer func(item T)) StreamI[T]
 
-// 	Sort(less func(a, b T) bool) StreamI[T]
+// 	Sorted(less func(a, b T) bool) StreamI[T]
 // 	Max(less func(a, b T) bool) (T, bool)
 // 	Min(less func(a, b T) bool) (T, bool)
 
@@ -312,6 +313,51 @@ func (s stream[T]) Range(start, end int) stream[T] {
 	return FromSlice(source)
 }
 
+// Sorted returns a stream consisting of the elements of this stream, sorted according to the provided less function.
+func (s stream[T]) Sorted(less func(a, b T) bool) stream[T] {
+	source := []T{}
+	source = append(source, s.source...)
+
+	slice.SortBy(source, less)
+
+	return FromSlice(source)
+}
+
+// Max returns the maximum element of this stream according to the provided less function.
+// less: a > b
+func (s stream[T]) Max(less func(a, b T) bool) (T, bool) {
+	var max T
+
+	if len(s.source) == 0 {
+		return max, false
+	}
+
+	for i, v := range s.source {
+		if less(v, max) || i == 0 {
+			max = v
+		}
+	}
+	return max, true
+}
+
+// Min returns the minimum element of this stream according to the provided less function.
+// less: a < b
+func (s stream[T]) Min(less func(a, b T) bool) (T, bool) {
+	var min T
+
+	if len(s.source) == 0 {
+		return min, false
+	}
+
+	for i, v := range s.source {
+		if less(v, min) || i == 0 {
+			min = v
+		}
+	}
+
+	return min, true
+}
+
 // ToSlice return the elements in the stream.
 func (s stream[T]) ToSlice() []T {
 	return s.source

stream/stream_test.go

@@ -303,3 +303,36 @@ func TestStream_Concat(t *testing.T) {
 
 	assert.Equal([]int{1, 2, 3, 4, 5, 6}, s.ToSlice())
 }
+
+func TestStream_Sorted(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_Sorted")
+
+	s := FromSlice([]int{4, 2, 1, 3})
+
+	s1 := s.Sorted(func(a, b int) bool { return a < b })
+
+	assert.Equal([]int{4, 2, 1, 3}, s.ToSlice())
+	assert.Equal([]int{1, 2, 3, 4}, s1.ToSlice())
+}
+
+func TestStream_Max(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_Max")
+
+	s := FromSlice([]int{4, 2, 1, 3})
+
+	max, ok := s.Max(func(a, b int) bool { return a > b })
+
+	assert.Equal(4, max)
+	assert.Equal(true, ok)
+}
+
+func TestStream_Min(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_Min")
+
+	s := FromSlice([]int{4, 2, 1, 3})
+
+	max, ok := s.Max(func(a, b int) bool { return a < b })
+
+	assert.Equal(1, max)
+	assert.Equal(true, ok)
+}