Merge pull request #17 from azihsoyn/feature/ResultAs

support ResultAs

distinct_test.go

@@ -27,6 +27,10 @@ func TestDistinct_HavingError(t *testing.T) {
 	assert := assert.New(t)
 	_, err := gollection.New("not slice value").Distinct().Distinct().Result()
 	assert.Error(err)
+
+	res := []int{}
+	err = gollection.New("not slice value").Distinct().Distinct().ResultAs(&res)
+	assert.Error(err)
 }
 
 func TestDistinctBy(t *testing.T) {

example_test.go

@@ -102,3 +102,48 @@ func Example_take() {
 	// Output: [1 2 3] <nil>
 	// [1 2 3 4 5 6 7 8 9 10] <nil>
 }
+
+func Example_customType() {
+	type User struct {
+		ID   int
+		Name string
+	}
+
+	in := []User{
+		{ID: 1, Name: "aaa"},
+		{ID: 2, Name: "bbb"},
+		{ID: 3, Name: "ccc"},
+		{ID: 4, Name: "ddd"},
+		{ID: 5, Name: "eee"},
+		{ID: 6, Name: "fff"},
+		{ID: 7, Name: "ggg"},
+	}
+	res, err := gollection.New(in).Filter(func(v User) bool {
+		return v.ID > 5
+	}).Result()
+	fmt.Printf("%#v %#v\n", res.([]User), err)
+	// Output: []gollection_test.User{gollection_test.User{ID:6, Name:"fff"}, gollection_test.User{ID:7, Name:"ggg"}} <nil>
+}
+
+func Example_customTypeWithResultAs() {
+	type User struct {
+		ID   int
+		Name string
+	}
+
+	in := []User{
+		{ID: 1, Name: "aaa"},
+		{ID: 2, Name: "bbb"},
+		{ID: 3, Name: "ccc"},
+		{ID: 4, Name: "ddd"},
+		{ID: 5, Name: "eee"},
+		{ID: 6, Name: "fff"},
+		{ID: 7, Name: "ggg"},
+	}
+	var res []User
+	err := gollection.New(in).Filter(func(v User) bool {
+		return v.ID > 5
+	}).ResultAs(&res)
+	fmt.Printf("%#v %#v\n", res, err)
+	// Output: []gollection_test.User{gollection_test.User{ID:6, Name:"fff"}, gollection_test.User{ID:7, Name:"ggg"}} <nil>
+}

examples/custom_type/main.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/azihsoyn/gollection"
+)
+
+type User struct {
+	ID   int
+	Name string
+}
+
+func main() {
+	in := []User{
+		{ID: 1, Name: "aaa"},
+		{ID: 2, Name: "bbb"},
+		{ID: 3, Name: "ccc"},
+		{ID: 4, Name: "ddd"},
+		{ID: 5, Name: "eee"},
+		{ID: 6, Name: "fff"},
+		{ID: 7, Name: "ggg"},
+	}
+	var out []User
+	err := gollection.New(in).Filter(func(v User) bool {
+		return v.ID > 5
+	}).ResultAs(&out)
+	fmt.Printf("out with ResultAs       : %#v\n", out)
+	fmt.Println("err : ", err)
+
+	ret, _ := gollection.New(in).Filter(func(v User) bool {
+		return v.ID > 5
+	}).Result()
+	out = ret.([]User)
+	fmt.Printf("out with type assertion : %#v\n", out)
+}

fold_test.go

@@ -27,6 +27,7 @@ func TestFold(t *testing.T) {
 	assert.NoError(err)
 	assert.Equal(expect, res)
 }
+
 func TestFold_NotSlice(t *testing.T) {
 	assert := assert.New(t)
 	_, err := gollection.New("not slice value").Fold(100, func(v1, v2 interface{}) interface{} {
@@ -44,11 +45,11 @@ func TestFold_HavingError(t *testing.T) {
 	assert := assert.New(t)
 	_, err := gollection.New("not slice value").
 		Fold(100, func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Fold(100, func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Result()
 	assert.Error(err)
 }
@@ -90,11 +91,11 @@ func TestFold_Stream_HavingError(t *testing.T) {
 	assert := assert.New(t)
 	_, err := gollection.NewStream("not slice value").
 		Fold(100, func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Fold(100, func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Result()
 	assert.Error(err)
 }

gollection.go

@@ -38,6 +38,25 @@ func (g *gollection) result() (interface{}, error) {
 	return g.slice, g.err
 }
 
+func (g *gollection) ResultAs(out interface{}) error {
+	if g.err != nil {
+		return g.err
+	}
+
+	iv := reflect.ValueOf(g.slice)
+	if g.val != nil {
+		iv = reflect.ValueOf(g.val)
+	}
+
+	ov := reflect.ValueOf(out)
+	if ov.Kind() != reflect.Ptr || iv.Type() != ov.Elem().Type() {
+		return fmt.Errorf("gollection.ResultAs called with unexpected type %T, expected %s", g.slice, ov.Elem().Type())
+	}
+
+	ov.Elem().Set(iv)
+	return nil
+}
+
 func (g *gollection) resultStream() (interface{}, error) {
 	var ret reflect.Value
 	var initialized bool

gollection_test.go

@@ -0,0 +1,17 @@
+package gollection_test
+
+import (
+	"testing"
+
+	"github.com/azihsoyn/gollection"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestResultAs_UnexpectedType(t *testing.T) {
+	assert := assert.New(t)
+	arr := []int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
+	res := []string{}
+
+	err := gollection.New(arr).ResultAs(&res)
+	assert.Error(err)
+}

reduce_test.go

@@ -19,6 +19,13 @@ func TestReduce(t *testing.T) {
 	assert.NoError(err)
 	assert.Equal(expect, res)
 
+	var ret int
+	err = gollection.New(arr).Reduce(func(v1, v2 int) int {
+		return v1 + v2
+	}).ResultAs(&ret)
+	assert.NoError(err)
+	assert.Equal(expect, ret)
+
 	arr = []int{1}
 	expect = 1
 
@@ -53,11 +60,11 @@ func TestReduce_HavingError(t *testing.T) {
 	assert := assert.New(t)
 	_, err := gollection.New("not slice value").
 		Reduce(func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Reduce(func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Result()
 	assert.Error(err)
 }
@@ -108,11 +115,11 @@ func TestReduce_Stream_HavingError(t *testing.T) {
 	assert := assert.New(t)
 	_, err := gollection.NewStream("not slice value").
 		Reduce(func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Reduce(func(v1, v2 interface{}) interface{} {
-		return ""
-	}).
+			return ""
+		}).
 		Result()
 	assert.Error(err)
 }