From 8ddf335e681fd0b9d6d0267497fa2ccc06afd663 Mon Sep 17 00:00:00 2001
From: Zachary Yedidia <zyedidia@gmail.com>
Date: Sun, 9 Feb 2020 14:58:37 -0500
Subject: [PATCH] Improve remove performance

---
 internal/buffer/eventhandler.go | 19 ++++++++++---------
 internal/buffer/line_array.go   | 12 +++++++-----
 internal/buffer/loc.go          |  2 +-
 3 files changed, 18 insertions(+), 15 deletions(-)

diff --git a/internal/buffer/eventhandler.go b/internal/buffer/eventhandler.go
index c271195d..cc737586 100644
--- a/internal/buffer/eventhandler.go
+++ b/internal/buffer/eventhandler.go
@@ -2,7 +2,6 @@ package buffer
 
 import (
 	"bytes"
-	"log"
 	"time"
 	"unicode/utf8"
 
@@ -124,33 +123,35 @@ func (eh *EventHandler) InsertBytes(start Loc, text []byte) {
 		Deltas:    []Delta{{text, start, Loc{0, 0}}},
 		Time:      time.Now(),
 	}
-	// oldl := eh.buf.LinesNum()
+	oldl := eh.buf.LinesNum()
 	eh.Execute(e)
-	// linecount := eh.buf.LinesNum() - oldl
+	linecount := eh.buf.LinesNum() - oldl
 	textcount := utf8.RuneCount(text)
 	lastnl := bytes.LastIndex(text, []byte{'\n'})
 	var endX int
 	var textX int
 	if lastnl >= 0 {
-		endX = utf8.RuneCount(text[lastnl:])
+		endX = utf8.RuneCount(text[lastnl+1:])
 		textX = endX
 	} else {
-		// endX = start.X + textcount
+		endX = start.X + textcount
 		textX = textcount
 	}
 
-	e.Deltas[0].End = start.MoveLA(textcount, eh.buf.LineArray)
-	// e.Deltas[0].End = clamp(Loc{endX, start.Y + linecount}, eh.buf.LineArray)
+	e.Deltas[0].End = clamp(Loc{endX, start.Y + linecount}, eh.buf.LineArray)
 	end := e.Deltas[0].End
 
 	for _, c := range eh.cursors {
 		move := func(loc Loc) Loc {
-			log.Println("move", loc)
 			if start.Y != end.Y && loc.GreaterThan(start) {
 				loc.Y += end.Y - start.Y
 			} else if loc.Y == start.Y && loc.GreaterEqual(start) {
 				loc.Y += end.Y - start.Y
-				loc.X += textX
+				if lastnl >= 0 {
+					loc.X = textX
+				} else {
+					loc.X += textX
+				}
 			}
 			return loc
 		}
diff --git a/internal/buffer/line_array.go b/internal/buffer/line_array.go
index 0aa69d7a..517979c5 100644
--- a/internal/buffer/line_array.go
+++ b/internal/buffer/line_array.go
@@ -224,20 +224,18 @@ func (la *LineArray) split(pos Loc) {
 
 // removes from start to end
 func (la *LineArray) remove(start, end Loc) []byte {
-	sub := la.Substr(start, end)
+	// sub := la.Substr(start, end)
 	startX := runeToByteIndex(start.X, la.lines[start.Y].data)
 	endX := runeToByteIndex(end.X, la.lines[end.Y].data)
 	if start.Y == end.Y {
 		la.lines[start.Y].data = append(la.lines[start.Y].data[:startX], la.lines[start.Y].data[endX:]...)
 	} else {
-		for i := start.Y + 1; i <= end.Y-1; i++ {
-			la.deleteLine(start.Y + 1)
-		}
+		la.deleteLines(start.Y, end.Y-1)
 		la.deleteToEnd(Loc{startX, start.Y})
 		la.deleteFromStart(Loc{endX - 1, start.Y + 1})
 		la.joinLines(start.Y, start.Y+1)
 	}
-	return sub
+	return []byte{}
 }
 
 // deleteToEnd deletes from the end of a line to the position
@@ -255,6 +253,10 @@ func (la *LineArray) deleteLine(y int) {
 	la.lines = la.lines[:y+copy(la.lines[y:], la.lines[y+1:])]
 }
 
+func (la *LineArray) deleteLines(y1, y2 int) {
+	la.lines = la.lines[:y1+copy(la.lines[y1:], la.lines[y2:])]
+}
+
 // DeleteByte deletes the byte at a position
 func (la *LineArray) deleteByte(pos Loc) {
 	la.lines[pos.Y].data = la.lines[pos.Y].data[:pos.X+copy(la.lines[pos.Y].data[pos.X:], la.lines[pos.Y].data[pos.X+1:])]
diff --git a/internal/buffer/loc.go b/internal/buffer/loc.go
index 4fd66329..5687f977 100644
--- a/internal/buffer/loc.go
+++ b/internal/buffer/loc.go
@@ -139,7 +139,7 @@ func ByteOffset(pos Loc, buf *Buffer) int {
 // clamps a loc within a buffer
 func clamp(pos Loc, la *LineArray) Loc {
 	if pos.GreaterEqual(la.End()) {
-		return la.End().MoveLA(-1, la)
+		return la.End()
 	} else if pos.LessThan(la.Start()) {
 		return la.Start()
 	}