Remove panic from crdt.Text (#522)

json.Text is used by SDK and does not run on the server. So this commit
remains panic from json.Text to keep usability.

api/converter/from_bytes.go

@@ -175,7 +175,6 @@ func fromJSONText(
 	}
 
 	rgaTreeSplit := crdt.NewRGATreeSplit(crdt.InitialTextNode())
-
 	current := rgaTreeSplit.InitialHead()
 	for _, pbNode := range pbText.Nodes {
 		textNode, err := fromTextNode(pbNode)
@@ -190,7 +189,7 @@ func fromJSONText(
 		if insPrevID != nil {
 			insPrevNode := rgaTreeSplit.FindNode(insPrevID)
 			if insPrevNode == nil {
-				panic("insPrevNode should be presence")
+				return nil, fmt.Errorf("insPrevNode should be presence")
 			}
 			current.SetInsPrev(insPrevNode)
 		}

pkg/document/crdt/array.go

@@ -95,16 +95,20 @@ func (a *Array) StructureAsString() string {
 }
 
 // DeepCopy copies itself deeply.
-func (a *Array) DeepCopy() Element {
+func (a *Array) DeepCopy() (Element, error) {
 	elements := NewRGATreeList()
 
 	for _, node := range a.elements.Nodes() {
-		elements.Add(node.elem.DeepCopy())
+		copiedNode, err := node.elem.DeepCopy()
+		if err != nil {
+			return nil, err
+		}
+		elements.Add(copiedNode)
 	}
 
 	array := NewArray(elements, a.createdAt)
 	array.removedAt = a.removedAt
-	return array
+	return array, nil
 }
 
 // CreatedAt returns the creation time of this array.

pkg/document/crdt/counter.go

@@ -96,9 +96,9 @@ func (p *Counter) Marshal() string {
 }
 
 // DeepCopy copies itself deeply.
-func (p *Counter) DeepCopy() Element {
+func (p *Counter) DeepCopy() (Element, error) {
 	counter := *p
-	return &counter
+	return &counter, nil
 }
 
 // CreatedAt returns the creation time.

pkg/document/crdt/element.go

@@ -47,7 +47,7 @@ type Element interface {
 	Marshal() string
 
 	// DeepCopy copies itself deeply.
-	DeepCopy() Element
+	DeepCopy() (Element, error)
 
 	// CreatedAt returns the creation time of this element.
 	CreatedAt() *time.Ticket

pkg/document/crdt/object.go

@@ -94,16 +94,20 @@ func (o *Object) Marshal() string {
 }
 
 // DeepCopy copies itself deeply.
-func (o *Object) DeepCopy() Element {
+func (o *Object) DeepCopy() (Element, error) {
 	members := NewElementRHT()
 
 	for _, node := range o.memberNodes.Nodes() {
-		members.Set(node.key, node.elem.DeepCopy())
+		copiedNode, err := node.elem.DeepCopy()
+		if err != nil {
+			return nil, err
+		}
+		members.Set(node.key, copiedNode)
 	}
 
 	obj := NewObject(members, o.createdAt)
 	obj.removedAt = o.removedAt
-	return obj
+	return obj, nil
 }
 
 // CreatedAt returns the creation time of this object.

pkg/document/crdt/primitive.go

@@ -219,9 +219,9 @@ func (p *Primitive) Marshal() string {
 }
 
 // DeepCopy copies itself deeply.
-func (p *Primitive) DeepCopy() Element {
+func (p *Primitive) DeepCopy() (Element, error) {
 	primitive := *p
-	return &primitive
+	return &primitive, nil
 }
 
 // CreatedAt returns the creation time.

pkg/document/crdt/primitive_test.go

@@ -53,7 +53,8 @@ func TestPrimitive(t *testing.T) {
 			assert.Equal(t, prim.Value(), crdt.ValueFromBytes(prim.ValueType(), prim.Bytes()))
 			assert.Equal(t, prim.Marshal(), test.marshal)
 
-			copied := prim.DeepCopy()
+			copied, err := prim.DeepCopy()
+			assert.NoError(t, err)
 			assert.Equal(t, prim.CreatedAt(), copied.CreatedAt())
 			assert.Equal(t, prim.MovedAt(), copied.MovedAt())
 			assert.Equal(t, prim.Marshal(), copied.Marshal())

pkg/document/crdt/rga_tree_split.go

@@ -43,7 +43,8 @@ func NewRGATreeSplitNodeID(createdAt *time.Ticket, offset int) *RGATreeSplitNode
 
 // Compare returns an integer comparing two ID. The result will be 0 if
 // id==other, -1 if id < other, and +1 if id > other. If the receiver or
-// argument is nil, it would panic at runtime.
+// argument is nil, it would panic at runtime. This method is following
+// golang standard interface.
 func (id *RGATreeSplitNodeID) Compare(other llrb.Key) int {
 	if id == nil || other == nil {
 		panic("RGATreeSplitNodeID cannot be null")
@@ -330,47 +331,53 @@ func (s *RGATreeSplit[V]) findNodePos(index int) *RGATreeSplitNodePos {
 func (s *RGATreeSplit[V]) findNodeWithSplit(
 	pos *RGATreeSplitNodePos,
 	updatedAt *time.Ticket,
-) (*RGATreeSplitNode[V], *RGATreeSplitNode[V]) {
+) (*RGATreeSplitNode[V], *RGATreeSplitNode[V], error) {
 	absoluteID := pos.getAbsoluteID()
-	node := s.findFloorNodePreferToLeft(absoluteID)
+	node, err := s.findFloorNodePreferToLeft(absoluteID)
+	if err != nil {
+		return nil, nil, err
+	}
 
 	relativeOffset := absoluteID.offset - node.id.offset
 
-	s.splitNode(node, relativeOffset)
+	_, err = s.splitNode(node, relativeOffset)
+	if err != nil {
+		return nil, nil, err
+	}
 
 	for node.next != nil && node.next.createdAt().After(updatedAt) {
 		node = node.next
 	}
 
-	return node, node.next
+	return node, node.next, nil
 }
 
-func (s *RGATreeSplit[V]) findFloorNodePreferToLeft(id *RGATreeSplitNodeID) *RGATreeSplitNode[V] {
+func (s *RGATreeSplit[V]) findFloorNodePreferToLeft(id *RGATreeSplitNodeID) (*RGATreeSplitNode[V], error) {
 	node := s.findFloorNode(id)
 	if node == nil {
-		panic("the node of the given id should be found: " + s.StructureAsString())
+		return nil, fmt.Errorf("the node of the given id should be found: " + s.StructureAsString())
 	}
 
 	if id.offset > 0 && node.id.offset == id.offset {
 		// NOTE: InsPrev may not be present due to GC.
 		if node.insPrev == nil {
-			return node
+			return node, nil
 		}
 		node = node.insPrev
 	}
 
-	return node
+	return node, nil
 }
 
-func (s *RGATreeSplit[V]) splitNode(node *RGATreeSplitNode[V], offset int) *RGATreeSplitNode[V] {
+func (s *RGATreeSplit[V]) splitNode(node *RGATreeSplitNode[V], offset int) (*RGATreeSplitNode[V], error) {
 	if offset > node.contentLen() {
-		panic("offset should be less than or equal to length: " + s.StructureAsString())
+		return nil, fmt.Errorf("offset should be less than or equal to length: " + s.StructureAsString())
 	}
 
 	if offset == 0 {
-		return node
+		return node, nil
 	} else if offset == node.contentLen() {
-		return node.next
+		return node.next, nil
 	}
 
 	splitNode := node.split(offset)
@@ -383,7 +390,7 @@ func (s *RGATreeSplit[V]) splitNode(node *RGATreeSplitNode[V], offset int) *RGAT
 	}
 	splitNode.SetInsPrev(node)
 
-	return splitNode
+	return splitNode, nil
 }
 
 // InsertAfter inserts the given node after the given previous node.
@@ -439,10 +446,16 @@ func (s *RGATreeSplit[V]) edit(
 	latestCreatedAtMapByActor map[string]*time.Ticket,
 	content V,
 	editedAt *time.Ticket,
-) (*RGATreeSplitNodePos, map[string]*time.Ticket) {
+) (*RGATreeSplitNodePos, map[string]*time.Ticket, error) {
 	// 01. Split nodes with from and to
-	toLeft, toRight := s.findNodeWithSplit(to, editedAt)
-	fromLeft, fromRight := s.findNodeWithSplit(from, editedAt)
+	toLeft, toRight, err := s.findNodeWithSplit(to, editedAt)
+	if err != nil {
+		return nil, nil, err
+	}
+	fromLeft, fromRight, err := s.findNodeWithSplit(from, editedAt)
+	if err != nil {
+		return nil, nil, err
+	}
 
 	// 02. delete between from and to
 	nodesToDelete := s.findBetween(fromRight, toRight)
@@ -467,7 +480,7 @@ func (s *RGATreeSplit[V]) edit(
 		s.removedNodeMap[key] = removedNode
 	}
 
-	return caretPos, latestCreatedAtMap
+	return caretPos, latestCreatedAtMap, nil
 }
 
 func (s *RGATreeSplit[V]) findBetween(from, to *RGATreeSplitNode[V]) []*RGATreeSplitNode[V] {

pkg/document/crdt/root.go

@@ -101,8 +101,12 @@ func (r *Root) RegisterTextElementWithGarbage(textType TextElement) {
 }
 
 // DeepCopy copies itself deeply.
-func (r *Root) DeepCopy() *Root {
-	return NewRoot(r.object.DeepCopy().(*Object))
+func (r *Root) DeepCopy() (*Root, error) {
+	copiedObject, err := r.object.DeepCopy()
+	if err != nil {
+		return nil, err
+	}
+	return NewRoot(copiedObject.(*Object)), nil
 }
 
 // GarbageCollect purge elements that were removed before the given time.

pkg/document/crdt/root_test.go

@@ -59,25 +59,29 @@ func TestRoot(t *testing.T) {
 		text := crdt.NewText(crdt.NewRGATreeSplit(crdt.InitialTextNode()), ctx.IssueTimeTicket())
 
 		fromPos, toPos := text.CreateRange(0, 0)
-		text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
+		_, _, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, "Hello World", text.String())
 		assert.Equal(t, 0, root.GarbageLen())
 
 		fromPos, toPos = text.CreateRange(5, 10)
-		text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
+		_, _, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, "HelloYorkied", text.String())
 		assert.Equal(t, 1, root.GarbageLen())
 
 		fromPos, toPos = text.CreateRange(0, 5)
-		text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
+		_, _, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, "Yorkied", text.String())
 		assert.Equal(t, 2, root.GarbageLen())
 
 		fromPos, toPos = text.CreateRange(6, 7)
-		text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
+		_, _, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, "Yorkie", text.String())
 		assert.Equal(t, 3, root.GarbageLen())
@@ -115,7 +119,8 @@ func TestRoot(t *testing.T) {
 
 		for _, tc := range tests {
 			fromPos, toPos := text.CreateRange(tc.from, tc.to)
-			text.Edit(fromPos, toPos, nil, tc.content, nil, ctx.IssueTimeTicket())
+			_, _, err := text.Edit(fromPos, toPos, nil, tc.content, nil, ctx.IssueTimeTicket())
+			assert.NoError(t, err)
 			registerTextElementWithGarbage(fromPos, toPos, root, text)
 			assert.Equal(t, tc.want, text.String())
 			assert.Equal(t, tc.garbage, root.GarbageLen())
@@ -131,19 +136,22 @@ func TestRoot(t *testing.T) {
 		text := crdt.NewText(crdt.NewRGATreeSplit(crdt.InitialTextNode()), ctx.IssueTimeTicket())
 
 		fromPos, toPos := text.CreateRange(0, 0)
-		text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
+		_, _, err := text.Edit(fromPos, toPos, nil, "Hello World", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, `[{"val":"Hello World"}]`, text.Marshal())
 		assert.Equal(t, 0, root.GarbageLen())
 
 		fromPos, toPos = text.CreateRange(6, 11)
-		text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
+		_, _, err = text.Edit(fromPos, toPos, nil, "Yorkie", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, `[{"val":"Hello "},{"val":"Yorkie"}]`, text.Marshal())
 		assert.Equal(t, 1, root.GarbageLen())
 
 		fromPos, toPos = text.CreateRange(0, 6)
-		text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
+		_, _, err = text.Edit(fromPos, toPos, nil, "", nil, ctx.IssueTimeTicket())
+		assert.NoError(t, err)
 		registerTextElementWithGarbage(fromPos, toPos, root, text)
 		assert.Equal(t, `[{"val":"Yorkie"}]`, text.Marshal())
 		assert.Equal(t, 2, root.GarbageLen())

pkg/document/crdt/text.go

@@ -166,23 +166,23 @@ func (t *Text) Marshal() string {
 }
 
 // DeepCopy copies itself deeply.
-func (t *Text) DeepCopy() Element {
+func (t *Text) DeepCopy() (Element, error) {
 	rgaTreeSplit := NewRGATreeSplit(InitialTextNode())
-
 	current := rgaTreeSplit.InitialHead()
+
 	for _, node := range t.Nodes() {
 		current = rgaTreeSplit.InsertAfter(current, node.DeepCopy())
 		insPrevID := node.InsPrevID()
 		if insPrevID != nil {
 			insPrevNode := rgaTreeSplit.FindNode(insPrevID)
 			if insPrevNode == nil {
-				panic("insPrevNode should be presence")
+				return nil, fmt.Errorf("insPrevNode should be presence")
 			}
 			current.SetInsPrev(insPrevNode)
 		}
 	}
 
-	return NewText(rgaTreeSplit, t.createdAt)
+	return NewText(rgaTreeSplit, t.createdAt), nil
 }
 
 // CreatedAt returns the creation time of this Text.
@@ -233,21 +233,19 @@ func (t *Text) Edit(
 	content string,
 	attributes map[string]string,
 	executedAt *time.Ticket,
-) (*RGATreeSplitNodePos, map[string]*time.Ticket) {
+) (*RGATreeSplitNodePos, map[string]*time.Ticket, error) {
 	val := NewTextValue(content, NewRHT())
 	for key, value := range attributes {
 		val.attrs.Set(key, value, executedAt)
 	}
 
-	cursorPos, latestCreatedAtMapByActor := t.rgaTreeSplit.edit(
+	return t.rgaTreeSplit.edit(
 		from,
 		to,
 		latestCreatedAtMapByActor,
 		val,
 		executedAt,
 	)
-
-	return cursorPos, latestCreatedAtMapByActor
 }
 
 // Style applies the given attributes of the given range.
@@ -256,10 +254,16 @@ func (t *Text) Style(
 	to *RGATreeSplitNodePos,
 	attributes map[string]string,
 	executedAt *time.Ticket,
-) {
+) error {
 	// 01. Split nodes with from and to
-	_, toRight := t.rgaTreeSplit.findNodeWithSplit(to, executedAt)
-	_, fromRight := t.rgaTreeSplit.findNodeWithSplit(from, executedAt)
+	_, toRight, err := t.rgaTreeSplit.findNodeWithSplit(to, executedAt)
+	if err != nil {
+		return err
+	}
+	_, fromRight, err := t.rgaTreeSplit.findNodeWithSplit(from, executedAt)
+	if err != nil {
+		return err
+	}
 
 	// 02. style nodes between from and to
 	nodes := t.rgaTreeSplit.findBetween(fromRight, toRight)
@@ -269,6 +273,7 @@ func (t *Text) Style(
 			val.attrs.Set(key, value, executedAt)
 		}
 	}
+	return nil
 }
 
 // Select stores that the given range has been selected.