Add copy node function

.github/workflows/ci.yaml

@@ -32,14 +32,14 @@ jobs:
       - name: Test
         env:
           GOFLAGS: ${{ matrix.flags }}
-        run: go test -coverprofile=profile.out -covermode=atomic -v -coverpkg=./... ./...
+        run: go test -coverprofile=profile-go${{ matrix.go-version }}${{ matrix.flags }}.out -covermode=atomic -v -coverpkg=./... ./...
 
       - name: Upload artifact
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
-          name: coverage
+          name: coverage-go${{ matrix.go-version }}${{ matrix.flags }}
           path: |
-            profile.out
+            profile-go${{ matrix.go-version }}${{ matrix.flags }}.out
           if-no-files-found: error
           retention-days: 1
 
@@ -52,9 +52,10 @@ jobs:
         uses: actions/checkout@v4
 
       - name: Download artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
-          name: coverage
+          pattern: coverage-*
+          merge-multiple: true
 
       - name: Send coverage
         uses: codecov/codecov-action@v3

insane.go

@@ -1290,6 +1290,65 @@ func (n *Node) MutateToStrict() *StrictNode {
 	return &StrictNode{n}
 }
 
+// ConvertToRoot **experimental** **not safe** function. It converts the node to `Root` and
+// removes it from its parent tree. The root parameter must the root of the current node,
+// so the converted root node utilizes the same decoder and nodePool. The node's parent is
+// becoming `nil` so it behaves like normal root node (e.g. on `(*Node).Suicide`).
+//
+// This function can be used when it is needed to use JSON subtree as a whole tree with
+// the root on the subtree top node. For example when treating array elements as separate
+// JSON trees.
+//
+// This function is unsafe because it shares the same decoder as its parent tree while the
+// decoder itself points to the parent root and that can lead to some unexpected behaviour.
+func (n *Node) ConvertToRoot(root *Root) *Root {
+	// remove node from its parent tree
+	n.Suicide()
+	n.parent = nil
+	return &Root{
+		n,
+		root.decoder,
+	}
+}
+
+// CopyFromNode copies all data from the src node to the current node.
+// `root` must be a root of the current node to utilize the same node pool.
+// If the `src` node is a node tree, the whole tree will be copied recursively.
+// This function is designed to use for copying data from node of one JSON tree
+// to another so they don't mutate each others data and utilize their own node
+// pools so the garbage collector can clean released nodes correctly.
+func (n *Node) CopyFromNode(root *Root, src *Node) *Node {
+	if n == nil || src == nil {
+		return nil
+	}
+
+	n.bits = src.bits
+	n.data = strings.Clone(src.data)
+	n.next = n.getNode(root)
+	n.next.parent = n.parent
+	n.next.CopyFromNode(root, src.next)
+
+	if len(src.nodes) > 0 {
+		n.nodes = make([]*Node, 0, len(src.nodes))
+		for _, child := range src.nodes {
+			newChild := n.getNode(root)
+			newChild.parent = n
+			n.nodes = append(n.nodes, newChild.CopyFromNode(root, child))
+		}
+	}
+
+	if src.fields != nil {
+		srcFields := *src.fields
+		newFields := make(map[string]int, len(srcFields))
+		for k, v := range srcFields {
+			newFields[k] = v
+		}
+		n.fields = &newFields
+	}
+
+	return n
+}
+
 func (n *Node) DigField(path ...string) *Node {
 	if n == nil || len(path) == 0 {
 		return nil
@@ -1806,17 +1865,25 @@ func (n *Node) getIndex() int {
 // ******************** //
 
 func (d *decoder) initPool() {
-	d.nodePool = make([]*Node, StartNodePoolSize, StartNodePoolSize)
+	s := make([]Node, StartNodePoolSize)
+	d.nodePool = make([]*Node, StartNodePoolSize)
 	for i := 0; i < StartNodePoolSize; i++ {
-		d.nodePool[i] = &Node{}
+		d.nodePool[i] = &s[i]
 	}
 }
 
 func (d *decoder) expandPool() []*Node {
 	c := cap(d.nodePool)
+	newSlice := make([]*Node, 0, c+c)
+	newSlice = append(newSlice, d.nodePool...)
+	s := make([]Node, c)
 	for i := 0; i < c; i++ {
-		d.nodePool = append(d.nodePool, &Node{})
+		newSlice = append(newSlice, &s[i])
+	}
+	for i := range d.nodePool {
+		d.nodePool[i] = nil
 	}
+	d.nodePool = newSlice
 
 	return d.nodePool
 }

insane_test.go

@@ -204,7 +204,6 @@ func TestDecodeErr(t *testing.T) {
 		{json: `falsenull`, err: ErrUnexpectedJSONEnding},
 		{json: `null:`, err: ErrUnexpectedJSONEnding},
 
-
 		// ok
 		{json: `0`, err: nil},
 		{json: `1.0`, err: nil},
@@ -374,7 +373,7 @@ func TestAddElement(t *testing.T) {
 		for index := 0; index < test.count; index++ {
 			root.AddElement()
 			l := len(root.AsArray())
-			assert.True(t, root.Dig(strconv.Itoa(l - 1)).IsNull(), "wrong node type")
+			assert.True(t, root.Dig(strconv.Itoa(l-1)).IsNull(), "wrong node type")
 		}
 		assert.Equal(t, test.result, root.EncodeToString(), "wrong encoding")
 		Release(root)
@@ -1054,3 +1053,49 @@ func TestIndex(t *testing.T) {
 
 	assert.Equal(t, index, node.getIndex(), "wrong index")
 }
+
+func TestCopyFromNode(t *testing.T) {
+	json := `{"first":["s1","s2","s3"],"second":[{"s4":true},{"s5":false}]}`
+	root1, err := DecodeString(json)
+	assert.NoError(t, err, "error while decoding")
+	assert.NotNil(t, root1, "node shouldn't be nil")
+
+	root2 := Spawn()
+	clonedRoot := root2.CopyFromNode(root2, root1.Node)
+	assert.NotNil(t, clonedRoot, "node shouldn't be nil")
+
+	array1 := root1.Dig("first").AsArray()
+	array2 := root2.Dig("first").AsArray()
+	assert.Equal(t, len(array1), len(array2))
+	for i := range array1 {
+		assert.Equal(t, array1[i].AsString(), array2[i].AsString())
+	}
+
+	origVal := strings.Clone(array1[0].data)
+	array2[0].data = "newData"
+	assert.NotEqual(t, array1[0].AsString(), array2[0].AsString(), "values must be different, first value must be %q, but it was changed to %q", origVal, array1[0].data)
+}
+
+func TestConvertToRoot(t *testing.T) {
+	json := `[{"a":"1"},{"b":"2"},{"c":"3"}]`
+	root1, err := DecodeString(json)
+	assert.NoError(t, err, "error while decoding")
+	assert.NotNil(t, root1, "root shouldn't be nil")
+	assert.True(t, len(root1.AsArray()) == 3, "root must be an array with 3 elements")
+
+	node2 := root1.Dig("2")
+	assert.NotNil(t, node2, "node shouldn't be nil")
+	assert.True(t, node2.IsObject(), "node must be an object")
+
+	root1FieldVal := node2.Dig("c")
+	assert.NotNil(t, root1FieldVal, "node must not be nil")
+
+	root2 := node2.ConvertToRoot(root1)
+	assert.NotNil(t, root2, "root shouldn't be nil")
+	// after ConvertToRoot the node is deleted from its parent tree
+	assert.Nil(t, root1.Dig("2"), "node must be nil")
+
+	root2FieldVal := root2.Dig("c")
+	assert.NotNil(t, root2FieldVal, "node must not be nil")
+	assert.Equal(t, root1FieldVal.AsString(), root2FieldVal.AsString(), "values must be equal")
+}