Add diff gutter

internal/action/actions.go

@@ -1195,6 +1195,21 @@ func (h *BufPane) HalfPageDown() bool {
 	return true
 }
 
+// ToggleDiffGutter turns the diff gutter off and on
+func (h *BufPane) ToggleDiffGutter() bool {
+	if !h.Buf.Settings["diffgutter"].(bool) {
+		h.Buf.Settings["diffgutter"] = true
+		h.Buf.UpdateDiff(func(synchronous bool) {
+			screen.DrawChan <- true
+		})
+		InfoBar.Message("Enabled diff gutter")
+	} else {
+		h.Buf.Settings["diffgutter"] = false
+		InfoBar.Message("Disabled diff gutter")
+	}
+	return true
+}
+
 // ToggleRuler turns line numbers off and on
 func (h *BufPane) ToggleRuler() bool {
 	if !h.Buf.Settings["ruler"].(bool) {

internal/action/bufpane.go

@@ -573,6 +573,7 @@ var BufKeyActions = map[string]BufKeyAction{
 	"EndOfLine":              (*BufPane).EndOfLine,
 	"ToggleHelp":             (*BufPane).ToggleHelp,
 	"ToggleKeyMenu":          (*BufPane).ToggleKeyMenu,
+	"ToggleDiffGutter":       (*BufPane).ToggleDiffGutter,
 	"ToggleRuler":            (*BufPane).ToggleRuler,
 	"ClearStatus":            (*BufPane).ClearStatus,
 	"ShellMode":              (*BufPane).ShellMode,

internal/action/infopane.go

@@ -123,6 +123,7 @@ var InfoNones = []string{
 	"HalfPageDown",
 	"ToggleHelp",
 	"ToggleKeyMenu",
+	"ToggleDiffGutter",
 	"ToggleRuler",
 	"JumpLine",
 	"ClearStatus",

internal/buffer/buffer.go

@@ -24,6 +24,7 @@ import (
 	"golang.org/x/text/encoding/htmlindex"
 	"golang.org/x/text/encoding/unicode"
 	"golang.org/x/text/transform"
+	dmp "github.com/sergi/go-diff/diffmatchpatch"
 )
 
 const backupTime = 8000
@@ -97,6 +98,15 @@ func (b *SharedBuffer) remove(start, end Loc) []byte {
 	return b.LineArray.remove(start, end)
 }
 
+const (
+	DSUnchanged    = 0
+	DSAdded        = 1
+	DSModified     = 2
+	DSDeletedAbove = 3
+)
+
+type DiffStatus byte
+
 // Buffer stores the main information about a currently open file including
 // the actual text (in a LineArray), the undo/redo stack (in an EventHandler)
 // all the cursors, the syntax highlighting info, the settings for the buffer
@@ -138,6 +148,12 @@ type Buffer struct {
 
 	Messages []*Message
 
+	updateDiffTimer   *time.Timer
+	diffBase          []byte
+	diffBaseLineCount int
+	diffLock          sync.RWMutex
+	diff              map[int]DiffStatus
+
 	// counts the number of edits
 	// resets every backupTime edits
 	lastbackup time.Time
@@ -930,6 +946,101 @@ func (b *Buffer) Write(bytes []byte) (n int, err error) {
 	return len(bytes), nil
 }
 
+func (b *Buffer) updateDiffSync() {
+	b.diffLock.Lock()
+	defer b.diffLock.Unlock()
+
+	b.diff = make(map[int]DiffStatus)
+
+	if b.diffBase == nil {
+		return
+	}
+
+	differ := dmp.New()
+	baseRunes, bufferRunes, _ := differ.DiffLinesToRunes(string(b.diffBase), string(b.Bytes()))
+	diffs := differ.DiffMainRunes(baseRunes, bufferRunes, false)
+	lineN := 0
+
+	for _, diff := range diffs {
+		lineCount := len([]rune(diff.Text))
+
+		switch diff.Type {
+		case dmp.DiffEqual:
+			lineN += lineCount
+		case dmp.DiffInsert:
+			var status DiffStatus
+			if b.diff[lineN] == DSDeletedAbove {
+				status = DSModified
+			} else {
+				status = DSAdded
+			}
+			for i := 0; i < lineCount; i++ {
+				b.diff[lineN] = status
+				lineN++
+			}
+		case dmp.DiffDelete:
+			b.diff[lineN] = DSDeletedAbove
+		}
+	}
+}
+
+// UpdateDiff computes the diff between the diff base and the buffer content.
+// The update may be performed synchronously or asynchronously.
+// UpdateDiff calls the supplied callback when the update is complete.
+// The argument passed to the callback is set to true if and only if
+// the update was performed synchronously.
+// If an asynchronous update is already pending when UpdateDiff is called,
+// UpdateDiff does not schedule another update, in which case the callback
+// is not called.
+func (b *Buffer) UpdateDiff(callback func(bool)) {
+	if b.updateDiffTimer != nil {
+		return
+	}
+
+	lineCount := b.LinesNum()
+	if b.diffBaseLineCount > lineCount {
+		lineCount = b.diffBaseLineCount
+	}
+
+	if lineCount < 1000 {
+		b.updateDiffSync()
+		callback(true)
+	} else if lineCount < 30000 {
+		b.updateDiffTimer = time.AfterFunc(500*time.Millisecond, func() {
+			b.updateDiffTimer = nil
+			b.updateDiffSync()
+			callback(false)
+		})
+	} else {
+		// Don't compute diffs for very large files
+		b.diffLock.Lock()
+		b.diff = make(map[int]DiffStatus)
+		b.diffLock.Unlock()
+		callback(true)
+	}
+}
+
+// SetDiffBase sets the text that is used as the base for diffing the buffer content
+func (b *Buffer) SetDiffBase(diffBase []byte) {
+	b.diffBase = diffBase
+	if diffBase == nil {
+		b.diffBaseLineCount = 0
+	} else {
+		b.diffBaseLineCount = strings.Count(string(diffBase), "\n")
+	}
+	b.UpdateDiff(func(synchronous bool) {
+		screen.DrawChan <- true
+	})
+}
+
+// DiffStatus returns the diff status for a line in the buffer
+func (b *Buffer) DiffStatus(lineN int) DiffStatus {
+	b.diffLock.RLock()
+	defer b.diffLock.RUnlock()
+	// Note that the zero value for DiffStatus is equal to DSUnchanged
+	return b.diff[lineN]
+}
+
 // WriteLog writes a string to the log buffer
 func WriteLog(s string) {
 	LogBuf.EventHandler.Insert(LogBuf.End(), s)

internal/config/settings.go

@@ -176,6 +176,7 @@ var defaultCommonSettings = map[string]interface{}{
 	"basename":       false,
 	"colorcolumn":    float64(0),
 	"cursorline":     true,
+	"diffgutter":     true,
 	"encoding":       "utf-8",
 	"eofnewline":     false,
 	"fastdirty":      true,

internal/display/bufwindow.go

@@ -212,6 +212,9 @@ func (w *BufWindow) LocFromVisual(svloc buffer.Loc) buffer.Loc {
 		if hasMessage {
 			vloc.X += 2
 		}
+		if b.Settings["diffgutter"].(bool) {
+			vloc.X++
+		}
 		if b.Settings["ruler"].(bool) {
 			vloc.X += maxLineNumLength + 1
 		}
@@ -273,6 +276,9 @@ func (w *BufWindow) LocFromVisual(svloc buffer.Loc) buffer.Loc {
 						break
 					}
 					vloc.X = 0
+					if b.Settings["diffgutter"].(bool) {
+						vloc.X++
+					}
 					// This will draw an empty line number because the current line is wrapped
 					if b.Settings["ruler"].(bool) {
 						vloc.X += maxLineNumLength + 1
@@ -311,6 +317,34 @@ func (w *BufWindow) drawGutter(vloc *buffer.Loc, bloc *buffer.Loc) {
 	vloc.X++
 }
 
+func (w *BufWindow) drawDiffGutter(backgroundStyle tcell.Style, softwrapped bool, vloc *buffer.Loc, bloc *buffer.Loc) {
+	symbol := ' '
+	styleName := ""
+
+	switch w.Buf.DiffStatus(bloc.Y) {
+	case buffer.DSAdded:
+		symbol = '\u258C' // Left half block
+		styleName = "diff-added"
+	case buffer.DSModified:
+		symbol = '\u258C' // Left half block
+		styleName = "diff-modified"
+	case buffer.DSDeletedAbove:
+		if !softwrapped {
+			symbol = '\u2594' // Upper one eighth block
+			styleName = "diff-deleted"
+		}
+	}
+
+	style := backgroundStyle
+	if s, ok := config.Colorscheme[styleName]; ok {
+		foreground, _, _ := s.Decompose()
+		style = style.Foreground(foreground)
+	}
+
+	screen.SetContent(w.X+vloc.X, w.Y+vloc.Y, symbol, nil, style)
+	vloc.X++
+}
+
 func (w *BufWindow) drawLineNum(lineNumStyle tcell.Style, softwrapped bool, maxLineNumLength int, vloc *buffer.Loc, bloc *buffer.Loc) {
 	lineNum := strconv.Itoa(bloc.Y + 1)
 
@@ -373,15 +407,33 @@ func (w *BufWindow) displayBuffer() {
 		bufWidth--
 	}
 
-	if b.Settings["syntax"].(bool) && b.SyntaxDef != nil {
-		for _, r := range b.Modifications {
-			final := -1
-			for i := r.X; i <= r.Y; i++ {
-				final = util.Max(b.Highlighter.ReHighlightStates(b, i), final)
+	if len(b.Modifications) > 0 {
+		if b.Settings["syntax"].(bool) && b.SyntaxDef != nil {
+			for _, r := range b.Modifications {
+				final := -1
+				for i := r.X; i <= r.Y; i++ {
+					final = util.Max(b.Highlighter.ReHighlightStates(b, i), final)
+				}
+				b.Highlighter.HighlightMatches(b, r.X, final+1)
 			}
-			b.Highlighter.HighlightMatches(b, r.X, final+1)
 		}
+
 		b.ClearModifications()
+
+		if b.Settings["diffgutter"].(bool) {
+			b.UpdateDiff(func(synchronous bool) {
+				// If the diff was updated asynchronously, the outer call to
+				// displayBuffer might already be completed and we need to
+				// schedule a redraw in order to display the new diff.
+				// Note that this cannot lead to an infinite recursion
+				// because the modifications were cleared above so there won't
+				// be another call to UpdateDiff when displayBuffer is called
+				// during the redraw.
+				if !synchronous {
+					screen.DrawChan <- true
+				}
+			})
+		}
 	}
 
 	var matchingBraces []buffer.Loc
@@ -444,18 +496,28 @@ func (w *BufWindow) displayBuffer() {
 	for vloc.Y = 0; vloc.Y < bufHeight; vloc.Y++ {
 		vloc.X = 0
 
+		currentLine := false
+		for _, c := range cursors {
+			if bloc.Y == c.Y && w.active {
+				currentLine = true
+				break
+			}
+		}
+
+		s := lineNumStyle
+		if currentLine {
+			s = curNumStyle
+		}
+
 		if hasMessage {
 			w.drawGutter(&vloc, &bloc)
 		}
 
+		if b.Settings["diffgutter"].(bool) {
+			w.drawDiffGutter(s, false, &vloc, &bloc)
+		}
+
 		if b.Settings["ruler"].(bool) {
-			s := lineNumStyle
-			for _, c := range cursors {
-				if bloc.Y == c.Y && w.active {
-					s = curNumStyle
-					break
-				}
-			}
 			w.drawLineNum(s, false, maxLineNumLength, &vloc, &bloc)
 		}
 
@@ -579,6 +641,9 @@ func (w *BufWindow) displayBuffer() {
 						break
 					}
 					vloc.X = 0
+					if b.Settings["diffgutter"].(bool) {
+						w.drawDiffGutter(lineNumStyle, true, &vloc, &bloc)
+					}
 					// This will draw an empty line number because the current line is wrapped
 					if b.Settings["ruler"].(bool) {
 						w.drawLineNum(lineNumStyle, true, maxLineNumLength, &vloc, &bloc)

runtime/colorschemes/atom-dark.micro

@@ -16,6 +16,9 @@ color-link tabbar "#1D1F21,#C5C8C6"
 color-link indent-char "#505050,#1D1F21"
 color-link line-number "#656866,#232526"
 color-link current-line-number "#656866,#1D1F21"
+color-link diff-added "#00AF00"
+color-link diff-modified "#FFAF00"
+color-link diff-deleted "#D70000"
 color-link gutter-error "#FF4444,#1D1F21"
 color-link gutter-warning "#EEEE77,#1D1F21"
 color-link cursor-line "#2D2F31"

runtime/colorschemes/bubblegum.micro

@@ -14,6 +14,9 @@ color-link underlined "underline 241,231"
 color-link todo "246,231"
 color-link statusline "241,254"
 color-link tabbar "241,254"
+color-link diff-added "34"
+color-link diff-modified "214"
+color-link diff-deleted "160"
 color-link gutter-error "197,231"
 color-link gutter-warning "134,231"
 color-link line-number "246,254"

runtime/colorschemes/cmc-16.micro

@@ -33,6 +33,9 @@ color-link statusline "white,blue"
 color-link tabbar "white,blue"
 color-link current-line-number "red"
 color-link current-line-number.scroller "red"
+color-link diff-added "green"
+color-link diff-modified "yellow"
+color-link diff-deleted "red"
 color-link gutter-error ",red"
 color-link gutter-warning "red"
 color-link color-column "cyan"

runtime/colorschemes/cmc-tc.micro

@@ -28,9 +28,12 @@ color-link statusline "#aaaaaa,#8a496b"
 color-link tabbar "#aaaaaa,#8a496b"
 color-link current-line-number "bold #e34234,#424549"
 color-link current-line-number.scroller "red"
+color-link diff-added "#00AF00"
+color-link diff-modified "#FFAF00"
+color-link diff-deleted "#D70000"
 color-link gutter-error ",#e34234"
 color-link gutter-warning "#e34234"
 color-link color-column "#f26522"
 color-link constant.bool "bold #55ffff"
 color-link constant.bool.true "bold #85ff85"
-color-link constant.bool.false "bold #ff8585"
+color-link constant.bool.false "bold #ff8585"

runtime/colorschemes/darcula.micro

@@ -17,6 +17,9 @@ color-link tabbar "#242424,#CCCCCC"
 color-link indent-char "#4F4F4F,#242424"
 color-link line-number "#666666,#2C2C2C"
 color-link current-line-number "#666666,#242424"
+color-link diff-added "#00AF00"
+color-link diff-modified "#FFAF00"
+color-link diff-deleted "#D70000"
 color-link gutter-error "#CB4B16,#242424"
 color-link gutter-warning "#E6DB74,#242424"
 color-link cursor-line "#2C2C2C"

runtime/colorschemes/default.micro

@@ -17,6 +17,9 @@ color-link tabbar "#282828,#F8F8F2"
 color-link indent-char "#505050,#282828"
 color-link line-number "#AAAAAA,#323232"
 color-link current-line-number "#AAAAAA,#282828"
+color-link diff-added "#00AF00"
+color-link diff-modified "#FFAF00"
+color-link diff-deleted "#D70000"
 color-link gutter-error "#CB4B16,#282828"
 color-link gutter-warning "#E6DB74,#282828"
 color-link cursor-line "#323232"

runtime/colorschemes/geany.micro

@@ -18,5 +18,8 @@ color-link current-line-number ""
 color-link statusline "black,white"
 color-link tabbar "black,white"
 color-link color-column "bold geren"
+color-link diff-added "green"
+color-link diff-modified "yellow"
+color-link diff-deleted "red"
 color-link gutter-error ",red"
 color-link gutter-warning "red"