shithub: hugo

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tpl/collections: Add collections.Reverse

Fixes #6499

--- a/tpl/collections/collections.go

+++ b/tpl/collections/collections.go

@@ -417,6 +417,29 @@

 	return qs.Encode(), nil

 }

+// Reverse creates a copy of slice and reverses it.

+func (ns *Namespace) Reverse(slice interface{}) (interface{}, error) {

+	if slice == nil {

+		return nil, nil

+	}

+	v := reflect.ValueOf(slice)

+

+	switch v.Kind() {

+	case reflect.Slice:

+	default:

+		return nil, errors.New("argument must be a slice")

+	}

+

+	sliceCopy := reflect.MakeSlice(v.Type(), v.Len(), v.Len())

+

+	for i := v.Len() - 1; i >= 0; i-- {

+		element := sliceCopy.Index(i)

+		element.Set(v.Index(v.Len() - 1 - i))

+	}

+

+	return sliceCopy.Interface(), nil

+}

+

 // Seq creates a sequence of integers.  It's named and used as GNU's seq.

 //

 // Examples:

--- a/tpl/collections/collections_test.go

+++ b/tpl/collections/collections_test.go

@@ -211,6 +211,25 @@

 	}

 }

+func TestReverse(t *testing.T) {

+	t.Parallel()

+	c := qt.New(t)

+	ns := New(&deps.Deps{})

+

+	s := []string{"a", "b", "c"}

+	reversed, err := ns.Reverse(s)

+	c.Assert(err, qt.IsNil)

+	c.Assert(reversed, qt.DeepEquals, []string{"c", "b", "a"}, qt.Commentf(fmt.Sprint(reversed)))

+	c.Assert(s, qt.DeepEquals, []string{"a", "b", "c"})

+

+	reversed, err = ns.Reverse(nil)

+	c.Assert(err, qt.IsNil)

+	c.Assert(reversed, qt.IsNil)

+	_, err = ns.Reverse(43)

+	c.Assert(err, qt.Not(qt.IsNil))

+

+}

+

 func TestEchoParam(t *testing.T) {

 	t.Parallel()

 	c := qt.New(t)