Make cursor movement automatic on insert + remove

This changes the behavior of cursor movement so that all cursors are
adjusted when a change is made to the buffer. Cursors don't have to be
manually moved after calling Insert or Remove, those functions will move
the cursor properly on their own.

This should fix issues 1-3 mentioned in the multiple cursors discussion.

Ref #5

cmd/micro/actions.go

@@ -554,7 +554,7 @@ func (v *View) InsertSpace(usePlugin bool) bool {
 		v.Cursor.ResetSelection()
 	}
 	v.Buf.Insert(v.Cursor.Loc, " ")
-	v.Cursor.Right()
+	// v.Cursor.Right()
 
 	if usePlugin {
 		return PostActionCall("InsertSpace", v)
@@ -574,15 +574,15 @@ func (v *View) InsertNewline(usePlugin bool) bool {
 		v.Cursor.ResetSelection()
 	}
 
-	v.Buf.Insert(v.Cursor.Loc, "\n")
 	ws := GetLeadingWhitespace(v.Buf.Line(v.Cursor.Y))
-	v.Cursor.Right()
+	v.Buf.Insert(v.Cursor.Loc, "\n")
+	// v.Cursor.Right()
 
 	if v.Buf.Settings["autoindent"].(bool) {
 		v.Buf.Insert(v.Cursor.Loc, ws)
-		for i := 0; i < len(ws); i++ {
-			v.Cursor.Right()
-		}
+		// for i := 0; i < len(ws); i++ {
+		// 	v.Cursor.Right()
+		// }
 
 		// Remove the whitespaces if keepautoindent setting is off
 		if IsSpacesOrTabs(v.Buf.Line(v.Cursor.Y-1)) && !v.Buf.Settings["keepautoindent"].(bool) {
@@ -622,18 +622,10 @@ func (v *View) Backspace(usePlugin bool) bool {
 		tabSize := int(v.Buf.Settings["tabsize"].(float64))
 		if v.Buf.Settings["tabstospaces"].(bool) && IsSpaces(lineStart) && len(lineStart) != 0 && len(lineStart)%tabSize == 0 {
 			loc := v.Cursor.Loc
-			v.Cursor.Loc = loc.Move(-tabSize, v.Buf)
-			cx, cy := v.Cursor.X, v.Cursor.Y
-			v.Cursor.Loc = loc
 			v.Buf.Remove(loc.Move(-tabSize, v.Buf), loc)
-			v.Cursor.X, v.Cursor.Y = cx, cy
 		} else {
-			v.Cursor.Left()
-			cx, cy := v.Cursor.X, v.Cursor.Y
-			v.Cursor.Right()
 			loc := v.Cursor.Loc
 			v.Buf.Remove(loc.Move(-1, v.Buf), loc)
-			v.Cursor.X, v.Cursor.Y = cx, cy
 		}
 	}
 	v.Cursor.LastVisualX = v.Cursor.GetVisualX()
@@ -753,7 +745,6 @@ func (v *View) OutdentLine(usePlugin bool) bool {
 			break
 		}
 		v.Buf.Remove(Loc{0, v.Cursor.Y}, Loc{1, v.Cursor.Y})
-		v.Cursor.X -= 1
 	}
 	v.Cursor.Relocate()
 
@@ -816,9 +807,9 @@ func (v *View) InsertTab(usePlugin bool) bool {
 	tabBytes := len(v.Buf.IndentString())
 	bytesUntilIndent := tabBytes - (v.Cursor.GetVisualX() % tabBytes)
 	v.Buf.Insert(v.Cursor.Loc, v.Buf.IndentString()[:bytesUntilIndent])
-	for i := 0; i < bytesUntilIndent; i++ {
-		v.Cursor.Right()
-	}
+	// for i := 0; i < bytesUntilIndent; i++ {
+	// 	v.Cursor.Right()
+	// }
 
 	if usePlugin {
 		return PostActionCall("InsertTab", v)
@@ -1088,7 +1079,7 @@ func (v *View) DuplicateLine(usePlugin bool) bool {
 	} else {
 		v.Cursor.End()
 		v.Buf.Insert(v.Cursor.Loc, "\n"+v.Buf.Line(v.Cursor.Y))
-		v.Cursor.Right()
+		// v.Cursor.Right()
 	}
 
 	messenger.Message("Duplicated line")
@@ -1810,7 +1801,7 @@ func (v *View) PlayMacro(usePlugin bool) bool {
 				v.Cursor.ResetSelection()
 			}
 			v.Buf.Insert(v.Cursor.Loc, string(t))
-			v.Cursor.Right()
+			// v.Cursor.Right()
 
 			for pl := range loadedPlugins {
 				_, err := Call(pl+".onRune", string(t), v)

cmd/micro/eventhandler.go

@@ -104,6 +104,16 @@ func (eh *EventHandler) Insert(start Loc, text string) {
 	}
 	eh.Execute(e)
 	e.Deltas[0].End = start.Move(Count(text), eh.buf)
+	end := e.Deltas[0].End
+
+	for _, c := range eh.buf.cursors {
+		if start.Y != end.Y && c.GreaterThan(start) {
+			c.Loc.Y += end.Y - start.Y
+		} else if c.Y == start.Y && c.GreaterEqual(start) {
+			c.Loc = c.Move(Count(text), eh.buf)
+		}
+		c.LastVisualX = c.GetVisualX()
+	}
 }
 
 // Remove creates a remove text event and executes it
@@ -115,6 +125,17 @@ func (eh *EventHandler) Remove(start, end Loc) {
 		Time:      time.Now(),
 	}
 	eh.Execute(e)
+
+	for _, c := range eh.buf.cursors {
+		if start.Y != end.Y && c.GreaterThan(end) {
+			c.Loc.Y -= end.Y - start.Y
+		} else if c.Y == end.Y && c.GreaterEqual(end) {
+			// TermMessage(start, end)
+			c.Loc = c.Move(-Diff(start, end, eh.buf), eh.buf)
+			// c.Loc = c.Move(ToCharPos(start, eh.buf)-ToCharPos(end, eh.buf), eh.buf)
+		}
+		c.LastVisualX = c.GetVisualX()
+	}
 }
 
 // MultipleReplace creates an multiple insertions executes them

cmd/micro/loc.go

@@ -54,6 +54,28 @@ type Loc struct {
 	X, Y int
 }
 
+func Diff(a, b Loc, buf *Buffer) int {
+	if a.Y == b.Y {
+		if a.X > b.X {
+			return a.X - b.X
+		}
+		return b.X - a.X
+	}
+
+	// Make sure a is guaranteed to be less than b
+	if b.LessThan(a) {
+		a, b = b, a
+	}
+
+	loc := 0
+	for i := a.Y + 1; i < b.Y; i++ {
+		// + 1 for the newline
+		loc += Count(buf.Line(i)) + 1
+	}
+	loc += Count(buf.Line(a.Y)) - a.X + b.X + 1
+	return loc
+}
+
 // LessThan returns true if b is smaller
 func (l Loc) LessThan(b Loc) bool {
 	if l.Y < b.Y {

cmd/micro/view.go

@@ -169,7 +169,7 @@ func (v *View) paste(clip string) {
 	}
 	clip = strings.Replace(clip, "\n", "\n"+leadingWS, -1)
 	v.Buf.Insert(v.Cursor.Loc, clip)
-	v.Cursor.Loc = v.Cursor.Loc.Move(Count(clip), v.Buf)
+	// v.Cursor.Loc = v.Cursor.Loc.Move(Count(clip), v.Buf)
 	v.freshClip = false
 	messenger.Message("Pasted clipboard")
 }
@@ -522,7 +522,6 @@ func (v *View) HandleEvent(event tcell.Event) {
 						v.Cursor.ResetSelection()
 					}
 					v.Buf.Insert(v.Cursor.Loc, string(e.Rune()))
-					v.Cursor.Right()
 
 					for pl := range loadedPlugins {
 						_, err := Call(pl+".onRune", string(e.Rune()), v)