Add persistent undo as the option

cmd/micro/buffer.go

@@ -41,6 +41,12 @@ type Buffer struct {
 	FileType string
 }
 
+// The SerializedBuffer holds the types that get serialized when a buffer is saved
+type SerializedBuffer struct {
+	EventHandler *EventHandler
+	Cursor       Cursor
+}
+
 // NewBuffer creates a new buffer from `txt` with path and name `path`
 func NewBuffer(txt, path string) *Buffer {
 	b := new(Buffer)
@@ -61,35 +67,36 @@ func NewBuffer(txt, path string) *Buffer {
 		os.Mkdir(configDir+"/buffers/", os.ModePerm)
 	}
 
-	if settings["savecursor"].(bool) {
+	// Put the cursor at the first spot
+	b.Cursor = Cursor{
+		X:   0,
+		Y:   0,
+		buf: b,
+	}
+
+	if settings["savecursor"].(bool) || settings["saveundo"].(bool) {
 		absPath, _ := filepath.Abs(b.Path)
 		file, err := os.Open(configDir + "/buffers/" + EscapePath(absPath))
 		if err == nil {
-			var cursor Cursor
+			var buffer SerializedBuffer
 			decoder := gob.NewDecoder(file)
-			err = decoder.Decode(&cursor)
+			gob.Register(TextEvent{})
+			err = decoder.Decode(&buffer)
 			if err != nil {
 				TermMessage(err.Error())
 			}
-			b.Cursor = cursor
-			b.Cursor.buf = b
-			b.Cursor.Clamp()
-		} else {
-			// Put the cursor at the first spot
-			b.Cursor = Cursor{
-				X:   0,
-				Y:   0,
-				buf: b,
+			if settings["savecursor"].(bool) {
+				b.Cursor = buffer.Cursor
+				b.Cursor.buf = b
+				b.Cursor.Clamp()
+			}
+
+			if settings["saveundo"].(bool) {
+				b.EventHandler = buffer.EventHandler
+				b.EventHandler.buf = b
 			}
 		}
 		file.Close()
-	} else {
-		// Put the cursor at the first spot
-		b.Cursor = Cursor{
-			X:   0,
-			Y:   0,
-			buf: b,
-		}
 	}
 
 	return b
@@ -121,12 +128,17 @@ func (b *Buffer) Save() error {
 
 // Serialize serializes the buffer to configDir/buffers
 func (b *Buffer) Serialize() error {
-	if settings["savecursor"].(bool) {
+	if settings["savecursor"].(bool) || settings["saveundo"].(bool) {
 		absPath, _ := filepath.Abs(b.Path)
 		file, err := os.Create(configDir + "/buffers/" + EscapePath(absPath))
 		if err == nil {
 			enc := gob.NewEncoder(file)
-			err = enc.Encode(b.Cursor)
+			gob.Register(TextEvent{})
+			err = enc.Encode(SerializedBuffer{
+				b.EventHandler,
+				b.Cursor,
+			})
+			// err = enc.Encode(b.Cursor)
 		}
 		file.Close()
 		return err
@@ -141,7 +153,7 @@ func (b *Buffer) SaveAs(filename string) error {
 	err := ioutil.WriteFile(filename, data, 0644)
 	if err == nil {
 		b.IsModified = false
-		err = b.Serialize()
+		return b.Serialize()
 	}
 	return err
 }

cmd/micro/cursor.go

@@ -74,6 +74,11 @@ func (c *Cursor) Clamp() {
 	}
 }
 
+func (c *Cursor) Goto(b Cursor) {
+	c.X, c.Y, c.LastVisualX = b.X, b.Y, b.LastVisualX
+	c.OrigSelection, c.CurSelection = b.OrigSelection, b.CurSelection
+}
+
 // SetLoc sets the location of the cursor in terms of character number
 // and not x, y location
 // It's just a simple wrapper of FromCharPos

cmd/micro/eventhandler.go

@@ -15,42 +15,42 @@ const (
 
 // TextEvent holds data for a manipulation on some text that can be undone
 type TextEvent struct {
-	c Cursor
+	C Cursor
 
-	eventType int
-	text      string
-	start     int
-	end       int
-	time      time.Time
+	EventType int
+	Text      string
+	Start     int
+	End       int
+	Time      time.Time
 }
 
 // ExecuteTextEvent runs a text event
 func ExecuteTextEvent(t *TextEvent, buf *Buffer) {
-	if t.eventType == TextEventInsert {
-		buf.insert(t.start, t.text)
-	} else if t.eventType == TextEventRemove {
-		t.text = buf.remove(t.start, t.end)
+	if t.EventType == TextEventInsert {
+		buf.insert(t.Start, t.Text)
+	} else if t.EventType == TextEventRemove {
+		t.Text = buf.remove(t.Start, t.End)
 	}
 }
 
 // UndoTextEvent undoes a text event
 func UndoTextEvent(t *TextEvent, buf *Buffer) {
-	t.eventType = -t.eventType
+	t.EventType = -t.EventType
 	ExecuteTextEvent(t, buf)
 }
 
 // EventHandler executes text manipulations and allows undoing and redoing
 type EventHandler struct {
-	buf  *Buffer
-	undo *Stack
-	redo *Stack
+	buf       *Buffer
+	UndoStack *Stack
+	RedoStack *Stack
 }
 
 // NewEventHandler returns a new EventHandler
 func NewEventHandler(buf *Buffer) *EventHandler {
 	eh := new(EventHandler)
-	eh.undo = new(Stack)
-	eh.redo = new(Stack)
+	eh.UndoStack = new(Stack)
+	eh.RedoStack = new(Stack)
 	eh.buf = buf
 	return eh
 }
@@ -58,12 +58,12 @@ func NewEventHandler(buf *Buffer) *EventHandler {
 // Insert creates an insert text event and executes it
 func (eh *EventHandler) Insert(start int, text string) {
 	e := &TextEvent{
-		c:         eh.buf.Cursor,
-		eventType: TextEventInsert,
-		text:      text,
-		start:     start,
-		end:       start + Count(text),
-		time:      time.Now(),
+		C:         eh.buf.Cursor,
+		EventType: TextEventInsert,
+		Text:      text,
+		Start:     start,
+		End:       start + Count(text),
+		Time:      time.Now(),
 	}
 	eh.Execute(e)
 }
@@ -71,11 +71,11 @@ func (eh *EventHandler) Insert(start int, text string) {
 // Remove creates a remove text event and executes it
 func (eh *EventHandler) Remove(start, end int) {
 	e := &TextEvent{
-		c:         eh.buf.Cursor,
-		eventType: TextEventRemove,
-		start:     start,
-		end:       end,
-		time:      time.Now(),
+		C:         eh.buf.Cursor,
+		EventType: TextEventRemove,
+		Start:     start,
+		End:       end,
+		Time:      time.Now(),
 	}
 	eh.Execute(e)
 }
@@ -88,38 +88,34 @@ func (eh *EventHandler) Replace(start, end int, replace string) {
 
 // Execute a textevent and add it to the undo stack
 func (eh *EventHandler) Execute(t *TextEvent) {
-	if eh.redo.Len() > 0 {
-		eh.redo = new(Stack)
+	if eh.RedoStack.Len() > 0 {
+		eh.RedoStack = new(Stack)
 	}
-	eh.undo.Push(t)
+	eh.UndoStack.Push(t)
 	ExecuteTextEvent(t, eh.buf)
 }
 
 // Undo the first event in the undo stack
 func (eh *EventHandler) Undo() {
-	t := eh.undo.Peek()
+	t := eh.UndoStack.Peek()
 	if t == nil {
 		return
 	}
 
-	te := t.(*TextEvent)
-	startTime := t.(*TextEvent).time.UnixNano() / int64(time.Millisecond)
+	startTime := t.Time.UnixNano() / int64(time.Millisecond)
 
 	eh.UndoOneEvent()
 
 	for {
-		t = eh.undo.Peek()
+		t = eh.UndoStack.Peek()
 		if t == nil {
 			return
 		}
 
-		te = t.(*TextEvent)
-
-		if startTime-(te.time.UnixNano()/int64(time.Millisecond)) > undoThreshold {
+		if startTime-(t.Time.UnixNano()/int64(time.Millisecond)) > undoThreshold {
 			return
-		} else {
-			startTime = t.(*TextEvent).time.UnixNano() / int64(time.Millisecond)
 		}
+		startTime = t.Time.UnixNano() / int64(time.Millisecond)
 
 		eh.UndoOneEvent()
 	}
@@ -129,46 +125,42 @@ func (eh *EventHandler) Undo() {
 func (eh *EventHandler) UndoOneEvent() {
 	// This event should be undone
 	// Pop it off the stack
-	t := eh.undo.Pop()
+	t := eh.UndoStack.Pop()
 	if t == nil {
 		return
 	}
 
-	te := t.(*TextEvent)
 	// Undo it
 	// Modifies the text event
-	UndoTextEvent(te, eh.buf)
+	UndoTextEvent(t, eh.buf)
 
 	// Set the cursor in the right place
-	teCursor := te.c
-	te.c = eh.buf.Cursor
-	eh.buf.Cursor = teCursor
+	teCursor := t.C
+	t.C = eh.buf.Cursor
+	eh.buf.Cursor.Goto(teCursor)
 
 	// Push it to the redo stack
-	eh.redo.Push(te)
+	eh.RedoStack.Push(t)
 }
 
 // Redo the first event in the redo stack
 func (eh *EventHandler) Redo() {
-	t := eh.redo.Peek()
+	t := eh.RedoStack.Peek()
 	if t == nil {
 		return
 	}
 
-	te := t.(*TextEvent)
-	startTime := t.(*TextEvent).time.UnixNano() / int64(time.Millisecond)
+	startTime := t.Time.UnixNano() / int64(time.Millisecond)
 
 	eh.RedoOneEvent()
 
 	for {
-		t = eh.redo.Peek()
+		t = eh.RedoStack.Peek()
 		if t == nil {
 			return
 		}
 
-		te = t.(*TextEvent)
-
-		if (te.time.UnixNano()/int64(time.Millisecond))-startTime > undoThreshold {
+		if (t.Time.UnixNano()/int64(time.Millisecond))-startTime > undoThreshold {
 			return
 		}
 
@@ -178,18 +170,17 @@ func (eh *EventHandler) Redo() {
 
 // RedoOneEvent redoes one event
 func (eh *EventHandler) RedoOneEvent() {
-	t := eh.redo.Pop()
+	t := eh.RedoStack.Pop()
 	if t == nil {
 		return
 	}
 
-	te := t.(*TextEvent)
 	// Modifies the text event
-	UndoTextEvent(te, eh.buf)
+	UndoTextEvent(t, eh.buf)
 
-	teCursor := te.c
-	te.c = eh.buf.Cursor
-	eh.buf.Cursor = teCursor
+	teCursor := t.C
+	t.C = eh.buf.Cursor
+	eh.buf.Cursor.Goto(teCursor)
 
-	eh.undo.Push(te)
+	eh.UndoStack.Push(t)
 }

cmd/micro/settings.go

@@ -78,6 +78,7 @@ func DefaultSettings() map[string]interface{} {
 		"indentchar":   " ",
 		"ruler":        true,
 		"savecursor":   false,
+		"saveundo":     false,
 		"scrollspeed":  float64(2),
 		"scrollmargin": float64(3),
 		"statusline":   true,

cmd/micro/stack.go

@@ -1,43 +1,43 @@
 package main
 
-// Stack is a simple implementation of a LIFO stack
+// Stack is a simple implementation of a LIFO stack for text events
 type Stack struct {
-	top  *Element
-	size int
+	Top  *Element
+	Size int
 }
 
 // An Element which is stored in the Stack
 type Element struct {
-	value interface{} // All types satisfy the empty interface, so we can store anything here.
-	next  *Element
+	Value *TextEvent
+	Next  *Element
 }
 
 // Len returns the stack's length
 func (s *Stack) Len() int {
-	return s.size
+	return s.Size
 }
 
 // Push a new element onto the stack
-func (s *Stack) Push(value interface{}) {
-	s.top = &Element{value, s.top}
-	s.size++
+func (s *Stack) Push(value *TextEvent) {
+	s.Top = &Element{value, s.Top}
+	s.Size++
 }
 
 // Pop removes the top element from the stack and returns its value
 // If the stack is empty, return nil
-func (s *Stack) Pop() (value interface{}) {
-	if s.size > 0 {
-		value, s.top = s.top.value, s.top.next
-		s.size--
+func (s *Stack) Pop() (value *TextEvent) {
+	if s.Size > 0 {
+		value, s.Top = s.Top.Value, s.Top.Next
+		s.Size--
 		return
 	}
 	return nil
 }
 
 // Peek returns the top element of the stack without removing it
-func (s *Stack) Peek() interface{} {
-	if s.size > 0 {
-		return s.top.value
+func (s *Stack) Peek() *TextEvent {
+	if s.Size > 0 {
+		return s.Top.Value
 	}
 	return nil
 }

cmd/micro/stack_test.go

@@ -1,39 +0,0 @@
-package main
-
-import "testing"
-
-func TestStack(t *testing.T) {
-	stack := new(Stack)
-
-	if stack.Len() != 0 {
-		t.Errorf("Len failed")
-	}
-	stack.Push(5)
-	stack.Push("test")
-	stack.Push(10)
-	if stack.Len() != 3 {
-		t.Errorf("Len failed")
-	}
-
-	var popped interface{}
-	popped = stack.Pop()
-	if popped != 10 {
-		t.Errorf("Pop failed")
-	}
-
-	popped = stack.Pop()
-	if popped != "test" {
-		t.Errorf("Pop failed")
-	}
-
-	stack.Push("test")
-	popped = stack.Pop()
-	if popped != "test" {
-		t.Errorf("Pop failed")
-	}
-	stack.Pop()
-	popped = stack.Pop()
-	if popped != nil {
-		t.Errorf("Pop failed")
-	}
-}

runtime/help/help.md

@@ -219,6 +219,11 @@ Here are the options that you can set:
 
     default value: `off`
 
+* `saveundo`: when this option is on, undo is saved even after you close a file
+   so if you close and reopen a file, you can keep undoing
+
+    default value: `off`
+
 * `scrollmargin`: amount of lines you would like to see above and below the cursor
 
 	default value: `3`

todolist.md

@@ -10,12 +10,12 @@
     - [ ] Horizontal splits
     - [ ] Vertical splits
 
-- [ ] Persistent undo/redo (saved between open and closing micro)
-
 - [ ] Wrap lines
 
 ### Done
 
+- [x] Persistent undo/redo (saved between open and closing micro)
+
 - [x] Auto indent
 
 - [x] Custom bindings