support unicode characters

vendor/github.com/jesseduffield/gocui/edit.go

@@ -4,7 +4,11 @@
 
 package gocui
 
-import "errors"
+import (
+	"errors"
+
+	"github.com/mattn/go-runewidth"
+)
 
 const maxInt = int(^uint(0) >> 1)
 
@@ -54,8 +58,9 @@ func simpleEditor(v *View, key Key, ch rune, mod Modifier) {
 
 // EditWrite writes a rune at the cursor position.
 func (v *View) EditWrite(ch rune) {
+	w := runewidth.RuneWidth(ch)
 	v.writeRune(v.cx, v.cy, ch)
-	v.MoveCursor(1, 0, true)
+	v.moveCursor(w, 0, true)
 }
 
 // EditDelete deletes a rune at the cursor position. back determines the
@@ -89,12 +94,12 @@ func (v *View) EditDelete(back bool) {
 					v.MoveCursor(-1, 0, true)
 				}
 			} else { // wrapped line
-				v.deleteRune(len(v.viewLines[y-1].line)-1, v.cy-1)
-				v.MoveCursor(-1, 0, true)
+				n, _ := v.deleteRune(len(v.viewLines[y-1].line)-1, v.cy-1)
+				v.MoveCursor(-n, 0, true)
 			}
 		} else { // middle/end of the line
-			v.deleteRune(v.cx-1, v.cy)
-			v.MoveCursor(-1, 0, true)
+			n, _ := v.deleteRune(v.cx-1, v.cy)
+			v.MoveCursor(-n, 0, true)
 		}
 	} else {
 		if x == len(v.viewLines[y].line) { // end of the line
@@ -116,35 +121,74 @@ func (v *View) EditNewLine() {
 // MoveCursor moves the cursor taking into account the width of the line/view,
 // displacing the origin if necessary.
 func (v *View) MoveCursor(dx, dy int, writeMode bool) {
+	ox, oy := v.cx+v.ox, v.cy+v.oy
+	x, y := ox+dx, oy+dy
+
+	if y < 0 || y >= len(v.viewLines) {
+		v.moveCursor(dx, dy, writeMode)
+		return
+	}
+
+	// Removing newline.
+	if x < 0 {
+		var prevLen int
+		if y-1 >= 0 && y-1 < len(v.viewLines) {
+			prevLen = lineWidth(v.viewLines[y-1].line)
+		}
+
+		v.MoveCursor(prevLen, -1, writeMode)
+		return
+	}
+
+	line := v.viewLines[y].line
+	var col int
+	var prevCol int
+	for i := range line {
+		prevCol = col
+		col += runewidth.RuneWidth(line[i].chr)
+		if dx > 0 {
+			if x <= col {
+				x = col
+				break
+			}
+			continue
+		}
+
+		if x < col {
+			x = prevCol
+			break
+		}
+	}
+
+	v.moveCursor(x-ox, y-oy, writeMode)
+}
+
+func (v *View) moveCursor(dx, dy int, writeMode bool) {
 	maxX, maxY := v.Size()
 	cx, cy := v.cx+dx, v.cy+dy
 	x, y := v.ox+cx, v.oy+cy
 
 	var curLineWidth, prevLineWidth int
 	// get the width of the current line
-	if writeMode {
-		if v.Wrap {
-			curLineWidth = maxX - 1
-		} else {
-			curLineWidth = maxInt
-		}
-	} else {
+	curLineWidth = maxInt
+	if v.Wrap {
+		curLineWidth = maxX - 1
+	}
+
+	if !writeMode {
+		curLineWidth = 0
 		if y >= 0 && y < len(v.viewLines) {
-			curLineWidth = len(v.viewLines[y].line)
+			curLineWidth = lineWidth(v.viewLines[y].line)
 			if v.Wrap && curLineWidth >= maxX {
 				curLineWidth = maxX - 1
 			}
-		} else {
-			curLineWidth = 0
 		}
 	}
 	// get the width of the previous line
+	prevLineWidth = 0
 	if y-1 >= 0 && y-1 < len(v.viewLines) {
-		prevLineWidth = len(v.viewLines[y-1].line)
-	} else {
-		prevLineWidth = 0
+		prevLineWidth = lineWidth(v.viewLines[y-1].line)
 	}
-
 	// adjust cursor's x position and view's x origin
 	if x > curLineWidth { // move to next line
 		if dx > 0 { // horizontal movement
@@ -190,10 +234,9 @@ func (v *View) MoveCursor(dx, dy int, writeMode bool) {
 				if !v.Wrap { // set origin so the EOL is visible
 					nox := prevLineWidth - maxX + 1
 					if nox < 0 {
-						v.ox = 0
-					} else {
-						v.ox = nox
+						nox = 0
 					}
+					v.ox = nox
 				}
 				v.cx = prevLineWidth
 			} else {
@@ -275,19 +318,31 @@ func (v *View) writeRune(x, y int, ch rune) error {
 
 // deleteRune removes a rune from the view's internal buffer, at the
 // position corresponding to the point (x, y).
-func (v *View) deleteRune(x, y int) error {
+// returns the amount of columns that where removed.
+func (v *View) deleteRune(x, y int) (int, error) {
 	v.tainted = true
 
 	x, y, err := v.realPosition(x, y)
 	if err != nil {
-		return err
+		return 0, err
 	}
 
 	if x < 0 || y < 0 || y >= len(v.lines) || x >= len(v.lines[y]) {
-		return errors.New("invalid point")
+		return 0, errors.New("invalid point")
 	}
-	v.lines[y] = append(v.lines[y][:x], v.lines[y][x+1:]...)
-	return nil
+
+	var tw int
+	for i := range v.lines[y] {
+		w := runewidth.RuneWidth(v.lines[y][i].chr)
+		tw += w
+		if tw > x {
+			v.lines[y] = append(v.lines[y][:i], v.lines[y][i+1:]...)
+			return w, nil
+		}
+
+	}
+
+	return 0, nil
 }
 
 // mergeLines merges the lines "y" and "y+1" if possible.