feat: add FindFirst, Reverse for stream

stream/stream.go

@@ -43,7 +43,7 @@ import (
 
 // 	// part of methods custom extension
 // 	Reverse() StreamI[T]
-// 	Range(start, end int64) StreamI[T]
+// 	Range(start, end int) StreamI[T]
 // 	Concat(streams ...StreamI[T]) StreamI[T]
 // }
 
@@ -255,6 +255,28 @@ func (s stream[T]) Count() int {
 	return len(s.source)
 }
 
+// FindFirst returns the first element of this stream and true, or zero value and false if the stream is empty.
+func (s stream[T]) FindFirst() (T, bool) {
+	var result T
+
+	if s.source == nil || len(s.source) == 0 {
+		return result, false
+	}
+
+	return s.source[0], true
+}
+
+// Reverse returns a stream whose elements are reverse order of given stream.
+func (s stream[T]) Reverse() stream[T] {
+	l := len(s.source)
+	source := make([]T, l)
+
+	for i := 0; i < l; i++ {
+		source[i] = s.source[l-1-i]
+	}
+	return FromSlice(source)
+}
+
 // ToSlice return the elements in the stream.
 func (s stream[T]) ToSlice() []T {
 	return s.source

stream/stream_test.go

@@ -247,3 +247,24 @@ func TestStream_Reduce(t *testing.T) {
 
 	assert.Equal(6, result)
 }
+
+func TestStream_FindFirst(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_FindFirst")
+
+	stream := FromSlice([]int{1, 2, 3})
+
+	result, ok := stream.FindFirst()
+
+	assert.Equal(1, result)
+	assert.Equal(true, ok)
+}
+
+func TestStream_Reverse(t *testing.T) {
+	assert := internal.NewAssert(t, "TestStream_Reverse")
+
+	s := FromSlice([]int{1, 2, 3})
+
+	rs := s.Reverse()
+
+	assert.Equal([]int{3, 2, 1}, rs.ToSlice())
+}