Adds Copy() function (#19)

elliotchance · Feb 5, 2021 · 724076b · 724076b
1 parent 5498093
commit 724076b
Show file tree

Hide file tree

Showing 4 changed files with 31 additions and 1 deletion.
diff --git a/go.mod b/go.mod
@@ -2,4 +2,4 @@ module github.com/elliotchance/orderedmap
 
 go 1.12
 
-require github.com/stretchr/testify v1.4.0
+require github.com/stretchr/testify v1.7.0
diff --git a/go.sum b/go.sum
@@ -5,7 +5,11 @@ github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZN
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
+github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/orderedmap.go b/orderedmap.go
@@ -136,3 +136,15 @@ func (m *OrderedMap) Back() *Element {
 		Value:   element.value,
 	}
 }
+
+// Copy returns a new OrderedMap with the same elements.
+// Using Copy while there are concurrent writes may mangle the result.
+func (m *OrderedMap) Copy() *OrderedMap {
+	m2 := NewOrderedMap()
+
+	for el := m.Front(); el != nil; el = el.Next() {
+		m2.Set(el.Key, el.Value)
+	}
+
+	return m2
+}
diff --git a/orderedmap_test.go b/orderedmap_test.go
@@ -304,6 +304,20 @@ func TestOrderedMap_Back(t *testing.T) {
 	})
 }
 
+func TestOrderedMap_Copy(t *testing.T) {
+	t.Run("ReturnsEqualButNotSame", func(t *testing.T) {
+		key, value := 1, "a value"
+		m := orderedmap.NewOrderedMap()
+		m.Set(key, value)
+
+		m2 := m.Copy()
+		m2.Set(key, "a different value")
+
+		assert.Equal(t, m.Len(), m2.Len(), "not all elements are copied")
+		assert.Equal(t, value, m.GetElement(key).Value)
+	})
+}
+
 func TestGetElement(t *testing.T) {
 	t.Run("ReturnsElementForKey", func(t *testing.T) {
 		m := orderedmap.NewOrderedMap()