From e5cbb074970c79b8286c615d5b5b16e72db55dd3 Mon Sep 17 00:00:00 2001
From: Mateusz Drewniak <matmg24@gmail.com>
Date: Fri, 28 Jul 2023 00:30:07 +0200
Subject: [PATCH] Fix horizontal cursor movements when there are grapheme
 clusters

---
 _example/http-prompt/main.go |   2 +-
 _example/live-prefix/main.go |   2 +-
 buffer.go                    |  40 ++++++---
 buffer_test.go               |  28 +++---
 document.go                  |  77 ++++++++++++++--
 document_test.go             | 166 +++++++++++++++++------------------
 emacs.go                     |  14 +--
 go.mod                       |   5 +-
 go.sum                       |   2 +
 key_bind_func.go             |   6 +-
 position.go                  | 103 +++++++---------------
 position_test.go             |   8 ++
 prompt.go                    |  63 +++++++------
 strings/strings.go           |  23 ++++-
 strings/strings_test.go      |  31 +++++++
 strings/units.go             |   4 +
 16 files changed, 337 insertions(+), 237 deletions(-)

diff --git a/_example/http-prompt/main.go b/_example/http-prompt/main.go
index df8e1091..67fbfb5e 100644
--- a/_example/http-prompt/main.go
+++ b/_example/http-prompt/main.go
@@ -164,7 +164,7 @@ func completer(in prompt.Document) ([]prompt.Suggest, istrings.RuneNumber, istri
 	if w == "" {
 		return []prompt.Suggest{}, 0, 0
 	}
-	startIndex := endIndex - istrings.RuneCount(w)
+	startIndex := endIndex - istrings.RuneCountInString(w)
 	return prompt.FilterHasPrefix(suggestions, w, true), startIndex, endIndex
 }
 
diff --git a/_example/live-prefix/main.go b/_example/live-prefix/main.go
index d4f9cb3c..a33e1357 100644
--- a/_example/live-prefix/main.go
+++ b/_example/live-prefix/main.go
@@ -21,7 +21,7 @@ func executor(in string) {
 func completer(in prompt.Document) ([]prompt.Suggest, istrings.RuneNumber, istrings.RuneNumber) {
 	endIndex := in.CurrentRuneIndex()
 	w := in.GetWordBeforeCursor()
-	startIndex := endIndex - istrings.RuneCount(w)
+	startIndex := endIndex - istrings.RuneCountInString(w)
 
 	s := []prompt.Suggest{
 		{Text: "users", Description: "Store the username and age"},
diff --git a/buffer.go b/buffer.go
index 6232f132..d0fc6682 100644
--- a/buffer.go
+++ b/buffer.go
@@ -69,13 +69,13 @@ func (b *Buffer) insertText(text string, columns istrings.Width, rows int, overw
 	if overwrite {
 		overwritten := string(currentTextRunes[cursor:])
 		if len(overwritten) >= int(cursor)+len(text) {
-			overwritten = string(currentTextRunes[cursor : cursor+istrings.RuneCount(text)])
+			overwritten = string(currentTextRunes[cursor : cursor+istrings.RuneCountInString(text)])
 		}
 		if i := strings.IndexAny(overwritten, "\n"); i != -1 {
 			overwritten = overwritten[:i]
 		}
 		b.setText(
-			string(currentTextRunes[:cursor])+text+string(currentTextRunes[cursor+istrings.RuneCount(overwritten):]),
+			string(currentTextRunes[:cursor])+text+string(currentTextRunes[cursor+istrings.RuneCountInString(overwritten):]),
 			columns,
 			rows,
 		)
@@ -88,7 +88,7 @@ func (b *Buffer) insertText(text string, columns istrings.Width, rows int, overw
 	}
 
 	if moveCursor {
-		b.cursorPosition += istrings.RuneCount(text)
+		b.cursorPosition += istrings.RuneCountInString(text)
 		b.recalculateStartLine(columns, rows)
 		b.updatePreferredColumn()
 	}
@@ -118,7 +118,7 @@ func (b *Buffer) recalculateStartLine(columns istrings.Width, rows int) bool {
 // (When doing this, make sure that the cursor_position is valid for this text.
 // text/cursor_position should be consistent at any time, otherwise set a Document instead.)
 func (b *Buffer) setText(text string, col istrings.Width, row int) {
-	debug.Assert(b.cursorPosition <= istrings.RuneCount(text), "length of input should be shorter than cursor position")
+	debug.Assert(b.cursorPosition <= istrings.RuneCountInString(text), "length of input should be shorter than cursor position")
 	b.workingLines[b.workingIndex] = text
 	b.recalculateStartLine(col, row)
 	b.resetPreferredColumn()
@@ -141,20 +141,32 @@ func (b *Buffer) setDocument(d *Document, columns istrings.Width, rows int) {
 	b.resetPreferredColumn()
 }
 
-// Move to the left on the current line.
+// Move to the left on the current line by the given amount of graphemes.
 // Returns true when the view should be rerendered.
-func (b *Buffer) CursorLeft(count istrings.RuneNumber, columns istrings.Width, rows int) bool {
-	l := b.Document().GetCursorLeftPosition(count)
-	b.cursorPosition += l
-	b.updatePreferredColumn()
-	return b.recalculateStartLine(columns, rows)
+func (b *Buffer) CursorLeft(count istrings.GraphemeNumber, columns istrings.Width, rows int) bool {
+	return b.cursorHorizontalMove(b.Document().GetCursorLeftPosition(count), columns, rows)
+}
+
+// Move to the left on the current line by the given amount of runes.
+// Returns true when the view should be rerendered.
+func (b *Buffer) CursorLeftRunes(count istrings.RuneNumber, columns istrings.Width, rows int) bool {
+	return b.cursorHorizontalMove(b.Document().GetCursorLeftPositionRunes(count), columns, rows)
 }
 
-// Move to the right on the current line.
+// Move to the right on the current line by the given amount of graphemes.
 // Returns true when the view should be rerendered.
-func (b *Buffer) CursorRight(count istrings.RuneNumber, columns istrings.Width, rows int) bool {
-	l := b.Document().GetCursorRightPosition(count)
-	b.cursorPosition += l
+func (b *Buffer) CursorRight(count istrings.GraphemeNumber, columns istrings.Width, rows int) bool {
+	return b.cursorHorizontalMove(b.Document().GetCursorRightPosition(count), columns, rows)
+}
+
+// Move to the right on the current line by the given amount of runes.
+// Returns true when the view should be rerendered.
+func (b *Buffer) CursorRightRunes(count istrings.RuneNumber, columns istrings.Width, rows int) bool {
+	return b.cursorHorizontalMove(b.Document().GetCursorRightPositionRunes(count), columns, rows)
+}
+
+func (b *Buffer) cursorHorizontalMove(count istrings.RuneNumber, columns istrings.Width, rows int) bool {
+	b.cursorPosition += count
 	b.updatePreferredColumn()
 	return b.recalculateStartLine(columns, rows)
 }
diff --git a/buffer_test.go b/buffer_test.go
index a8fea1c0..7dd220f0 100644
--- a/buffer_test.go
+++ b/buffer_test.go
@@ -25,8 +25,8 @@ func TestBuffer_InsertText(t *testing.T) {
 		t.Errorf("Text should be %#v, got %#v", "some_text", b.Text())
 	}
 
-	if b.cursorPosition != istrings.RuneCount("some_text") {
-		t.Errorf("cursorPosition should be %#v, got %#v", istrings.RuneCount("some_text"), b.cursorPosition)
+	if b.cursorPosition != istrings.RuneCountInString("some_text") {
+		t.Errorf("cursorPosition should be %#v, got %#v", istrings.RuneCountInString("some_text"), b.cursorPosition)
 	}
 }
 
@@ -38,8 +38,8 @@ func TestBuffer_InsertText_Overwrite(t *testing.T) {
 		t.Errorf("Text should be %#v, got %#v", "ABC", b.Text())
 	}
 
-	if b.cursorPosition != istrings.RuneCount("ABC") {
-		t.Errorf("cursorPosition should be %#v, got %#v", istrings.RuneCount("ABC"), b.cursorPosition)
+	if b.cursorPosition != istrings.RuneCountInString("ABC") {
+		t.Errorf("cursorPosition should be %#v, got %#v", istrings.RuneCountInString("ABC"), b.cursorPosition)
 	}
 
 	b.CursorLeft(1, DefColCount, DefRowCount)
@@ -87,8 +87,8 @@ func TestBuffer_CursorMovement(t *testing.T) {
 	if b.Text() != "some_teAxt" {
 		t.Errorf("Text should be %#v, got %#v", "some_teAxt", b.Text())
 	}
-	if b.cursorPosition != istrings.RuneCount("some_teA") {
-		t.Errorf("Text should be %#v, got %#v", istrings.RuneCount("some_teA"), b.cursorPosition)
+	if b.cursorPosition != istrings.RuneCountInString("some_teA") {
+		t.Errorf("Text should be %#v, got %#v", istrings.RuneCountInString("some_teA"), b.cursorPosition)
 	}
 
 	// Moving over left character counts.
@@ -97,8 +97,8 @@ func TestBuffer_CursorMovement(t *testing.T) {
 	if b.Text() != "Asome_teAxt" {
 		t.Errorf("Text should be %#v, got %#v", "some_teAxt", b.Text())
 	}
-	if b.cursorPosition != istrings.RuneCount("A") {
-		t.Errorf("Text should be %#v, got %#v", istrings.RuneCount("some_teA"), b.cursorPosition)
+	if b.cursorPosition != istrings.RuneCountInString("A") {
+		t.Errorf("Text should be %#v, got %#v", istrings.RuneCountInString("some_teA"), b.cursorPosition)
 	}
 
 	// TODO: Going right already at right end.
@@ -148,8 +148,8 @@ func TestBuffer_CursorDown(t *testing.T) {
 
 	// Normally going down
 	b.CursorDown(1, DefColCount, DefRowCount)
-	if b.Document().cursorPosition != istrings.RuneCount("line1\nlin") {
-		t.Errorf("Should be %#v, got %#v", istrings.RuneCount("line1\nlin"), b.Document().cursorPosition)
+	if b.Document().cursorPosition != istrings.RuneCountInString("line1\nlin") {
+		t.Errorf("Should be %#v, got %#v", istrings.RuneCountInString("line1\nlin"), b.Document().cursorPosition)
 	}
 
 	// Going down to a line that's storter.
@@ -157,8 +157,8 @@ func TestBuffer_CursorDown(t *testing.T) {
 	b.InsertTextMoveCursor("long line1\na\nb", DefColCount, DefRowCount, false)
 	b.cursorPosition = 3
 	b.CursorDown(1, DefColCount, DefRowCount)
-	if b.Document().cursorPosition != istrings.RuneCount("long line1\na") {
-		t.Errorf("Should be %#v, got %#v", istrings.RuneCount("long line1\na"), b.Document().cursorPosition)
+	if b.Document().cursorPosition != istrings.RuneCountInString("long line1\na") {
+		t.Errorf("Should be %#v, got %#v", istrings.RuneCountInString("long line1\na"), b.Document().cursorPosition)
 	}
 }
 
@@ -174,8 +174,8 @@ func TestBuffer_DeleteBeforeCursor(t *testing.T) {
 	if deleted != "e" {
 		t.Errorf("Should be %#v, got %#v", deleted, "e")
 	}
-	if b.cursorPosition != istrings.RuneCount("some_t") {
-		t.Errorf("Should be %#v, got %#v", istrings.RuneCount("some_t"), b.cursorPosition)
+	if b.cursorPosition != istrings.RuneCountInString("some_t") {
+		t.Errorf("Should be %#v, got %#v", istrings.RuneCountInString("some_t"), b.cursorPosition)
 	}
 
 	// Delete over the characters length before cursor.
diff --git a/document.go b/document.go
index a3ae1ff8..fad9b06b 100644
--- a/document.go
+++ b/document.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/elk-language/go-prompt/bisect"
 	istrings "github.com/elk-language/go-prompt/strings"
+	"github.com/rivo/uniseg"
 	"golang.org/x/exp/utf8string"
 )
 
@@ -142,7 +143,7 @@ func (d *Document) FindStartOfPreviousWord() istrings.ByteNumber {
 // of the text before the cursor until the start of the previous word.
 func (d *Document) FindRuneNumberUntilStartOfPreviousWord() istrings.RuneNumber {
 	x := d.TextBeforeCursor()
-	return istrings.RuneCount(x[d.FindStartOfPreviousWordWithSpace():])
+	return istrings.RuneCountInString(x[d.FindStartOfPreviousWordWithSpace():])
 }
 
 // FindStartOfPreviousWordWithSpace is almost the same as FindStartOfPreviousWord.
@@ -344,7 +345,7 @@ func (d *Document) CursorPositionRow() (row istrings.RuneNumber) {
 
 // TextEndPositionRow returns the row of the end of the current text. (0-based.)
 func (d *Document) TextEndPositionRow() (row istrings.RuneNumber) {
-	textLength := istrings.RuneCount(d.Text)
+	textLength := istrings.RuneCountInString(d.Text)
 	if textLength == 0 {
 		return 0
 	}
@@ -359,11 +360,41 @@ func (d *Document) CursorPositionCol() (col istrings.RuneNumber) {
 	return
 }
 
-// GetCursorLeftPosition returns the relative position for cursor left.
-func (d *Document) GetCursorLeftPosition(count istrings.RuneNumber) istrings.RuneNumber {
+// Returns the amount of runes that the cursors should be moved by.
+// The `count` argument tells this function by how many graphemes (visible characters)
+// the cursor should be moved (to the left).
+func (d *Document) GetCursorLeftPosition(count istrings.GraphemeNumber) istrings.RuneNumber {
 	if count < 0 {
 		return d.GetCursorRightPosition(-count)
 	}
+	if d.cursorPosition == 0 {
+		return 0
+	}
+	text := d.TextBeforeCursor()
+	g := uniseg.NewGraphemes(text)
+	graphemeLength := istrings.GraphemeCount(text)
+	var currentGraphemeIndex istrings.GraphemeNumber
+	var currentPosition istrings.RuneNumber
+
+	for g.Next() {
+		if currentGraphemeIndex >= graphemeLength-count {
+			break
+		}
+		currentPosition += istrings.RuneNumber(len(g.Runes()))
+		currentGraphemeIndex++
+	}
+
+	result := d.cursorPosition - currentPosition
+	return -result
+}
+
+// Returns the amount of runes that the cursors should be moved by.
+// The `count` argument tells this function by how many runes
+// the cursor should be moved (to the left).
+func (d *Document) GetCursorLeftPositionRunes(count istrings.RuneNumber) istrings.RuneNumber {
+	if count < 0 {
+		return d.GetCursorRightPositionRunes(-count)
+	}
 	runeSlice := []rune(d.Text)
 	var counter istrings.RuneNumber
 	targetPosition := d.cursorPosition - count
@@ -377,11 +408,39 @@ func (d *Document) GetCursorLeftPosition(count istrings.RuneNumber) istrings.Run
 	return counter
 }
 
-// GetCursorRightPosition returns relative position for cursor right.
-func (d *Document) GetCursorRightPosition(count istrings.RuneNumber) istrings.RuneNumber {
+// Returns the amount of runes that the cursors should be moved by.
+// The `count` argument tells this function by how many graphemes (visible characters)
+// the cursor should be moved (to the right).
+func (d *Document) GetCursorRightPosition(count istrings.GraphemeNumber) istrings.RuneNumber {
 	if count < 0 {
 		return d.GetCursorLeftPosition(-count)
 	}
+	text := d.TextAfterCursor()
+	if len(text) == 0 {
+		return 0
+	}
+
+	g := uniseg.NewGraphemes(text)
+	var currentGraphemeIndex istrings.GraphemeNumber
+	var currentPosition istrings.RuneNumber
+
+	for g.Next() {
+		if currentGraphemeIndex >= count {
+			break
+		}
+		currentPosition += istrings.RuneNumber(len(g.Runes()))
+		currentGraphemeIndex++
+	}
+	return currentPosition
+}
+
+// Returns the amount of runes that the cursors should be moved by.
+// The `count` argument tells this function by how many runes
+// the cursor should be moved (to the right).
+func (d *Document) GetCursorRightPositionRunes(count istrings.RuneNumber) istrings.RuneNumber {
+	if count < 0 {
+		return d.GetCursorLeftPositionRunes(-count)
+	}
 	runeSlice := []rune(d.Text)
 	var counter istrings.RuneNumber
 	targetPosition := d.cursorPosition + count
@@ -496,12 +555,12 @@ func (d *Document) OnLastLine() bool {
 
 // GetEndOfLinePosition returns relative position for the end of this line.
 func (d *Document) GetEndOfLinePosition() istrings.RuneNumber {
-	return istrings.RuneCount(d.CurrentLineAfterCursor())
+	return istrings.RuneCountInString(d.CurrentLineAfterCursor())
 }
 
 // GetStartOfLinePosition returns relative position for the start of this line.
 func (d *Document) GetStartOfLinePosition() istrings.RuneNumber {
-	return istrings.RuneCount(d.CurrentLineBeforeCursor())
+	return istrings.RuneCountInString(d.CurrentLineBeforeCursor())
 }
 
 // GetStartOfLinePosition returns relative position for the start of this line.
@@ -521,7 +580,7 @@ func (d *Document) FindStartOfFirstWordOfLine() istrings.RuneNumber {
 	}
 
 	if counter == 0 {
-		return istrings.RuneCount(line)
+		return istrings.RuneCountInString(line)
 	}
 
 	return counter
diff --git a/document_test.go b/document_test.go
index 56648d48..9c3c2db5 100644
--- a/document_test.go
+++ b/document_test.go
@@ -15,7 +15,7 @@ func ExampleDocument_CurrentLine() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.CurrentLine())
@@ -26,7 +26,7 @@ This is a exam`),
 func ExampleDocument_DisplayCursorPosition() {
 	d := &Document{
 		Text:           `Hello! my name is c-bata.`,
-		cursorPosition: istrings.RuneCount(`Hello`),
+		cursorPosition: istrings.RuneCountInString(`Hello`),
 	}
 	fmt.Println("DisplayCursorPosition", d.DisplayCursorPosition(50))
 	// Output:
@@ -39,7 +39,7 @@ func ExampleDocument_CursorPositionRow() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println("CursorPositionRow", d.CursorPositionRow())
@@ -53,7 +53,7 @@ func ExampleDocument_CursorPositionCol() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println("CursorPositionCol", d.CursorPositionCol())
@@ -67,7 +67,7 @@ func ExampleDocument_TextBeforeCursor() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.TextBeforeCursor())
@@ -82,7 +82,7 @@ func ExampleDocument_TextAfterCursor() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.TextAfterCursor())
@@ -107,7 +107,7 @@ func ExampleDocument_CurrentLineBeforeCursor() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.CurrentLineBeforeCursor())
@@ -121,7 +121,7 @@ func ExampleDocument_CurrentLineAfterCursor() {
 This is a example of Document component.
 This component has texts displayed in terminal and cursor position.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.CurrentLineAfterCursor())
@@ -134,7 +134,7 @@ func ExampleDocument_GetWordBeforeCursor() {
 		Text: `Hello! my name is c-bata.
 This is a example of Document component.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.GetWordBeforeCursor())
@@ -147,7 +147,7 @@ func ExampleDocument_GetWordAfterCursor() {
 		Text: `Hello! my name is c-bata.
 This is a example of Document component.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a exam`),
 	}
 	fmt.Println(d.GetWordAfterCursor())
@@ -160,7 +160,7 @@ func ExampleDocument_GetWordBeforeCursorWithSpace() {
 		Text: `Hello! my name is c-bata.
 This is a example of Document component.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a example `),
 	}
 	fmt.Println(d.GetWordBeforeCursorWithSpace())
@@ -173,7 +173,7 @@ func ExampleDocument_GetWordAfterCursorWithSpace() {
 		Text: `Hello! my name is c-bata.
 This is a example of Document component.
 `,
-		cursorPosition: istrings.RuneCount(`Hello! my name is c-bata.
+		cursorPosition: istrings.RuneCountInString(`Hello! my name is c-bata.
 This is a`),
 	}
 	fmt.Println(d.GetWordAfterCursorWithSpace())
@@ -184,7 +184,7 @@ This is a`),
 func ExampleDocument_GetWordBeforeCursorUntilSeparator() {
 	d := &Document{
 		Text:           `hello,i am c-bata`,
-		cursorPosition: istrings.RuneCount(`hello,i am c`),
+		cursorPosition: istrings.RuneCountInString(`hello,i am c`),
 	}
 	fmt.Println(d.GetWordBeforeCursorUntilSeparator(","))
 	// Output:
@@ -194,7 +194,7 @@ func ExampleDocument_GetWordBeforeCursorUntilSeparator() {
 func ExampleDocument_GetWordAfterCursorUntilSeparator() {
 	d := &Document{
 		Text:           `hello,i am c-bata,thank you for using go-prompt`,
-		cursorPosition: istrings.RuneCount(`hello,i a`),
+		cursorPosition: istrings.RuneCountInString(`hello,i a`),
 	}
 	fmt.Println(d.GetWordAfterCursorUntilSeparator(","))
 	// Output:
@@ -204,7 +204,7 @@ func ExampleDocument_GetWordAfterCursorUntilSeparator() {
 func ExampleDocument_GetWordBeforeCursorUntilSeparatorIgnoreNextToCursor() {
 	d := &Document{
 		Text:           `hello,i am c-bata,thank you for using go-prompt`,
-		cursorPosition: istrings.RuneCount(`hello,i am c-bata,`),
+		cursorPosition: istrings.RuneCountInString(`hello,i am c-bata,`),
 	}
 	fmt.Println(d.GetWordBeforeCursorUntilSeparatorIgnoreNextToCursor(","))
 	// Output:
@@ -214,7 +214,7 @@ func ExampleDocument_GetWordBeforeCursorUntilSeparatorIgnoreNextToCursor() {
 func ExampleDocument_GetWordAfterCursorUntilSeparatorIgnoreNextToCursor() {
 	d := &Document{
 		Text:           `hello,i am c-bata,thank you for using go-prompt`,
-		cursorPosition: istrings.RuneCount(`hello`),
+		cursorPosition: istrings.RuneCountInString(`hello`),
 	}
 	fmt.Println(d.GetWordAfterCursorUntilSeparatorIgnoreNextToCursor(","))
 	// Output:
@@ -269,7 +269,7 @@ func TestDocument_GetCharRelativeToCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "line 1\nline 2\nline 3\nline 4\n",
-				cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+				cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 			},
 			expected: "e",
 		},
@@ -306,7 +306,7 @@ func TestDocument_TextBeforeCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "line 1\nline 2\nline 3\nline 4\n",
-				cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+				cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 			},
 			expected: "line 1\nlin",
 		},
@@ -341,7 +341,7 @@ func TestDocument_TextAfterCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "line 1\nline 2\nline 3\nline 4\n",
-				cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+				cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 			},
 			expected: "e 2\nline 3\nline 4\n",
 		},
@@ -385,14 +385,14 @@ func TestDocument_GetWordBeforeCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple bana"),
+				cursorPosition: istrings.RuneCountInString("apple bana"),
 			},
 			expected: "bana",
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ./file/foo.json"),
+				cursorPosition: istrings.RuneCountInString("apply -f ./file/foo.json"),
 			},
 			expected: "foo.json",
 			sep:      " /",
@@ -400,14 +400,14 @@ func TestDocument_GetWordBeforeCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple banana orange",
-				cursorPosition: istrings.RuneCount("apple ba"),
+				cursorPosition: istrings.RuneCountInString("apple ba"),
 			},
 			expected: "ba",
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ./fi"),
+				cursorPosition: istrings.RuneCountInString("apply -f ./fi"),
 			},
 			expected: "fi",
 			sep:      " /",
@@ -415,7 +415,7 @@ func TestDocument_GetWordBeforeCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple ",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: "",
 		},
@@ -463,14 +463,14 @@ func TestDocument_GetWordBeforeCursorWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana ",
-				cursorPosition: istrings.RuneCount("apple bana "),
+				cursorPosition: istrings.RuneCountInString("apple bana "),
 			},
 			expected: "bana ",
 		},
 		{
 			document: &Document{
 				Text:           "apply -f /path/to/file/",
-				cursorPosition: istrings.RuneCount("apply -f /path/to/file/"),
+				cursorPosition: istrings.RuneCountInString("apply -f /path/to/file/"),
 			},
 			expected: "file/",
 			sep:      " /",
@@ -478,14 +478,14 @@ func TestDocument_GetWordBeforeCursorWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple ",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: "apple ",
 		},
 		{
 			document: &Document{
 				Text:           "path/",
-				cursorPosition: istrings.RuneCount("path/"),
+				cursorPosition: istrings.RuneCountInString("path/"),
 			},
 			expected: "path/",
 			sep:      " /",
@@ -534,14 +534,14 @@ func TestDocument_FindStartOfPreviousWord(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple bana"),
+				cursorPosition: istrings.RuneCountInString("apple bana"),
 			},
 			expected: istrings.Len("apple "),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ./file/foo.json"),
+				cursorPosition: istrings.RuneCountInString("apply -f ./file/foo.json"),
 			},
 			expected: istrings.Len("apply -f ./file/"),
 			sep:      " /",
@@ -549,14 +549,14 @@ func TestDocument_FindStartOfPreviousWord(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple ",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: istrings.Len("apple "),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ./"),
+				cursorPosition: istrings.RuneCountInString("apply -f ./"),
 			},
 			expected: istrings.Len("apply -f ./"),
 			sep:      " /",
@@ -605,14 +605,14 @@ func TestDocument_FindStartOfPreviousWordWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana ",
-				cursorPosition: istrings.RuneCount("apple bana "),
+				cursorPosition: istrings.RuneCountInString("apple bana "),
 			},
 			expected: istrings.Len("apple "),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f /file/foo/",
-				cursorPosition: istrings.RuneCount("apply -f /file/foo/"),
+				cursorPosition: istrings.RuneCountInString("apply -f /file/foo/"),
 			},
 			expected: istrings.Len("apply -f /file/"),
 			sep:      " /",
@@ -620,14 +620,14 @@ func TestDocument_FindStartOfPreviousWordWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple ",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: istrings.Len(""),
 		},
 		{
 			document: &Document{
 				Text:           "file/",
-				cursorPosition: istrings.RuneCount("file/"),
+				cursorPosition: istrings.RuneCountInString("file/"),
 			},
 			expected: istrings.Len(""),
 			sep:      " /",
@@ -676,14 +676,14 @@ func TestDocument_GetWordAfterCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple bana"),
+				cursorPosition: istrings.RuneCountInString("apple bana"),
 			},
 			expected: "",
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ./fi"),
+				cursorPosition: istrings.RuneCountInString("apply -f ./fi"),
 			},
 			expected: "le",
 			sep:      " /",
@@ -691,21 +691,21 @@ func TestDocument_GetWordAfterCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: "bana",
 		},
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple"),
+				cursorPosition: istrings.RuneCountInString("apple"),
 			},
 			expected: "",
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ."),
+				cursorPosition: istrings.RuneCountInString("apply -f ."),
 			},
 			expected: "",
 			sep:      " /",
@@ -713,7 +713,7 @@ func TestDocument_GetWordAfterCursor(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("ap"),
+				cursorPosition: istrings.RuneCountInString("ap"),
 			},
 			expected: "ple",
 		},
@@ -761,21 +761,21 @@ func TestDocument_GetWordAfterCursorWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple bana"),
+				cursorPosition: istrings.RuneCountInString("apple bana"),
 			},
 			expected: "",
 		},
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: "bana",
 		},
 		{
 			document: &Document{
 				Text:           "/path/to",
-				cursorPosition: istrings.RuneCount("/path/"),
+				cursorPosition: istrings.RuneCountInString("/path/"),
 			},
 			expected: "to",
 			sep:      " /",
@@ -783,7 +783,7 @@ func TestDocument_GetWordAfterCursorWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "/path/to/file",
-				cursorPosition: istrings.RuneCount("/path/"),
+				cursorPosition: istrings.RuneCountInString("/path/"),
 			},
 			expected: "to",
 			sep:      " /",
@@ -791,14 +791,14 @@ func TestDocument_GetWordAfterCursorWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple"),
+				cursorPosition: istrings.RuneCountInString("apple"),
 			},
 			expected: " bana",
 		},
 		{
 			document: &Document{
 				Text:           "path/to",
-				cursorPosition: istrings.RuneCount("path"),
+				cursorPosition: istrings.RuneCountInString("path"),
 			},
 			expected: "/to",
 			sep:      " /",
@@ -806,7 +806,7 @@ func TestDocument_GetWordAfterCursorWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("ap"),
+				cursorPosition: istrings.RuneCountInString("ap"),
 			},
 			expected: "ple",
 		},
@@ -854,21 +854,21 @@ func TestDocument_FindEndOfCurrentWord(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple bana"),
+				cursorPosition: istrings.RuneCountInString("apple bana"),
 			},
 			expected: istrings.Len(""),
 		},
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: istrings.Len("bana"),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ./"),
+				cursorPosition: istrings.RuneCountInString("apply -f ./"),
 			},
 			expected: istrings.Len("file"),
 			sep:      " /",
@@ -876,14 +876,14 @@ func TestDocument_FindEndOfCurrentWord(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple"),
+				cursorPosition: istrings.RuneCountInString("apple"),
 			},
 			expected: istrings.Len(""),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f ./file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f ."),
+				cursorPosition: istrings.RuneCountInString("apply -f ."),
 			},
 			expected: istrings.Len(""),
 			sep:      " /",
@@ -891,7 +891,7 @@ func TestDocument_FindEndOfCurrentWord(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("ap"),
+				cursorPosition: istrings.RuneCountInString("ap"),
 			},
 			expected: istrings.Len("ple"),
 		},
@@ -948,21 +948,21 @@ func TestDocument_FindEndOfCurrentWordWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple bana"),
+				cursorPosition: istrings.RuneCountInString("apple bana"),
 			},
 			expected: istrings.Len(""),
 		},
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple "),
+				cursorPosition: istrings.RuneCountInString("apple "),
 			},
 			expected: istrings.Len("bana"),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f /file/foo.json",
-				cursorPosition: istrings.RuneCount("apply -f /"),
+				cursorPosition: istrings.RuneCountInString("apply -f /"),
 			},
 			expected: istrings.Len("file"),
 			sep:      " /",
@@ -970,14 +970,14 @@ func TestDocument_FindEndOfCurrentWordWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("apple"),
+				cursorPosition: istrings.RuneCountInString("apple"),
 			},
 			expected: istrings.Len(" bana"),
 		},
 		{
 			document: &Document{
 				Text:           "apply -f /path/to",
-				cursorPosition: istrings.RuneCount("apply -f /path"),
+				cursorPosition: istrings.RuneCountInString("apply -f /path"),
 			},
 			expected: istrings.Len("/to"),
 			sep:      " /",
@@ -985,7 +985,7 @@ func TestDocument_FindEndOfCurrentWordWithSpace(t *testing.T) {
 		{
 			document: &Document{
 				Text:           "apple bana",
-				cursorPosition: istrings.RuneCount("ap"),
+				cursorPosition: istrings.RuneCountInString("ap"),
 			},
 			expected: istrings.Len("ple"),
 		},
@@ -1034,7 +1034,7 @@ func TestDocument_FindEndOfCurrentWordWithSpace(t *testing.T) {
 func TestDocument_CurrentLineBeforeCursor(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
 	ac := d.CurrentLineBeforeCursor()
 	ex := "lin"
@@ -1046,7 +1046,7 @@ func TestDocument_CurrentLineBeforeCursor(t *testing.T) {
 func TestDocument_CurrentLineAfterCursor(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
 	ac := d.CurrentLineAfterCursor()
 	ex := "e 2"
@@ -1058,7 +1058,7 @@ func TestDocument_CurrentLineAfterCursor(t *testing.T) {
 func TestDocument_CurrentLine(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
 	ac := d.CurrentLine()
 	ex := "line 2"
@@ -1074,7 +1074,7 @@ func TestDocument_CursorPositionRowAndCol(t *testing.T) {
 		expectedCol istrings.RuneNumber
 	}{
 		{
-			document:    &Document{Text: "line 1\nline 2\nline 3\n", cursorPosition: istrings.RuneCount("line 1\n" + "lin")},
+			document:    &Document{Text: "line 1\nline 2\nline 3\n", cursorPosition: istrings.RuneCountInString("line 1\n" + "lin")},
 			expectedRow: 1,
 			expectedCol: 3,
 		},
@@ -1099,7 +1099,7 @@ func TestDocument_CursorPositionRowAndCol(t *testing.T) {
 func TestDocument_GetCursorLeftPosition(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "line 2\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "line 2\n" + "lin"),
 	}
 	ac := d.GetCursorLeftPosition(2)
 	var ex istrings.RuneNumber = -2
@@ -1122,16 +1122,16 @@ func TestDocument_GetCursorLeftPosition(t *testing.T) {
 func TestDocument_GetCursorUpPosition(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "line 2\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "line 2\n" + "lin"),
 	}
 	ac := d.GetCursorUpPosition(2, -1)
-	ex := istrings.RuneCount("lin") - istrings.RuneCount("line 1\n"+"line 2\n"+"lin")
+	ex := istrings.RuneCountInString("lin") - istrings.RuneCountInString("line 1\n"+"line 2\n"+"lin")
 	if ac != ex {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
 
 	ac = d.GetCursorUpPosition(100, -1)
-	ex = istrings.RuneCount("lin") - istrings.RuneCount("line 1\n"+"line 2\n"+"lin")
+	ex = istrings.RuneCountInString("lin") - istrings.RuneCountInString("line 1\n"+"line 2\n"+"lin")
 	if ac != ex {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
@@ -1140,16 +1140,16 @@ func TestDocument_GetCursorUpPosition(t *testing.T) {
 func TestDocument_GetCursorDownPosition(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("lin"),
+		cursorPosition: istrings.RuneCountInString("lin"),
 	}
 	ac := d.GetCursorDownPosition(2, -1)
-	ex := istrings.RuneCount("line 1\n"+"line 2\n"+"lin") - istrings.RuneCount("lin")
+	ex := istrings.RuneCountInString("line 1\n"+"line 2\n"+"lin") - istrings.RuneCountInString("lin")
 	if ac != ex {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
 
 	ac = d.GetCursorDownPosition(100, -1)
-	ex = istrings.RuneCount("line 1\n"+"line 2\n"+"line 3\n"+"line 4\n") - istrings.RuneCount("lin")
+	ex = istrings.RuneCountInString("line 1\n"+"line 2\n"+"line 3\n"+"line 4\n") - istrings.RuneCountInString("lin")
 	if ac != ex {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
@@ -1158,7 +1158,7 @@ func TestDocument_GetCursorDownPosition(t *testing.T) {
 func TestDocument_GetCursorRightPosition(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "line 2\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "line 2\n" + "lin"),
 	}
 	ac := d.GetCursorRightPosition(2)
 	var ex istrings.RuneNumber = 2
@@ -1181,7 +1181,7 @@ func TestDocument_GetCursorRightPosition(t *testing.T) {
 func TestDocument_Lines(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
 	ac := d.Lines()
 	ex := []string{"line 1", "line 2", "line 3", "line 4", ""}
@@ -1193,7 +1193,7 @@ func TestDocument_Lines(t *testing.T) {
 func TestDocument_LineCount(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
 	ac := d.LineCount()
 	ex := 5
@@ -1205,9 +1205,9 @@ func TestDocument_LineCount(t *testing.T) {
 func TestDocument_TranslateIndexToPosition(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
-	row, col := d.TranslateIndexToPosition(istrings.RuneCount("line 1\nline 2\nlin"))
+	row, col := d.TranslateIndexToPosition(istrings.RuneCountInString("line 1\nline 2\nlin"))
 	if row != 2 {
 		t.Errorf("Should be %#v, got %#v", 2, row)
 	}
@@ -1226,10 +1226,10 @@ func TestDocument_TranslateIndexToPosition(t *testing.T) {
 func TestDocument_TranslateRowColToIndex(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3\nline 4\n",
-		cursorPosition: istrings.RuneCount("line 1\n" + "lin"),
+		cursorPosition: istrings.RuneCountInString("line 1\n" + "lin"),
 	}
 	ac := d.TranslateRowColToIndex(2, 3)
-	ex := istrings.RuneCount("line 1\nline 2\nlin")
+	ex := istrings.RuneCountInString("line 1\nline 2\nlin")
 	if ac != ex {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
@@ -1243,13 +1243,13 @@ func TestDocument_TranslateRowColToIndex(t *testing.T) {
 func TestDocument_OnLastLine(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3",
-		cursorPosition: istrings.RuneCount("line 1\nline"),
+		cursorPosition: istrings.RuneCountInString("line 1\nline"),
 	}
 	ac := d.OnLastLine()
 	if ac {
 		t.Errorf("Should be %#v, got %#v", false, ac)
 	}
-	d.cursorPosition = istrings.RuneCount("line 1\nline 2\nline")
+	d.cursorPosition = istrings.RuneCountInString("line 1\nline 2\nline")
 	ac = d.OnLastLine()
 	if !ac {
 		t.Errorf("Should be %#v, got %#v", true, ac)
@@ -1259,10 +1259,10 @@ func TestDocument_OnLastLine(t *testing.T) {
 func TestDocument_GetEndOfLinePosition(t *testing.T) {
 	d := &Document{
 		Text:           "line 1\nline 2\nline 3",
-		cursorPosition: istrings.RuneCount("line 1\nli"),
+		cursorPosition: istrings.RuneCountInString("line 1\nli"),
 	}
 	ac := d.GetEndOfLinePosition()
-	ex := istrings.RuneCount("ne 2")
+	ex := istrings.RuneCountInString("ne 2")
 	if ac != ex {
 		t.Errorf("Should be %#v, got %#v", ex, ac)
 	}
diff --git a/emacs.go b/emacs.go
index 09098b7a..223646f4 100644
--- a/emacs.go
+++ b/emacs.go
@@ -46,8 +46,8 @@ var emacsKeyBindings = []KeyBind{
 	{
 		Key: ControlE,
 		Fn: func(p *Prompt) bool {
-			return p.CursorRight(
-				istrings.RuneCount(p.Buffer.Document().CurrentLineAfterCursor()),
+			return p.CursorRightRunes(
+				istrings.RuneCountInString(p.Buffer.Document().CurrentLineAfterCursor()),
 			)
 		},
 	},
@@ -55,7 +55,7 @@ var emacsKeyBindings = []KeyBind{
 	{
 		Key: ControlA,
 		Fn: func(p *Prompt) bool {
-			return p.CursorLeft(
+			return p.CursorLeftRunes(
 				p.Buffer.Document().FindStartOfFirstWordOfLine(),
 			)
 		},
@@ -65,7 +65,7 @@ var emacsKeyBindings = []KeyBind{
 		Key: ControlK,
 		Fn: func(p *Prompt) bool {
 			p.Buffer.Delete(
-				istrings.RuneCount(p.Buffer.Document().CurrentLineAfterCursor()),
+				istrings.RuneCountInString(p.Buffer.Document().CurrentLineAfterCursor()),
 				p.renderer.col,
 				p.renderer.row,
 			)
@@ -77,7 +77,7 @@ var emacsKeyBindings = []KeyBind{
 		Key: ControlU,
 		Fn: func(p *Prompt) bool {
 			p.Buffer.DeleteBeforeCursor(
-				istrings.RuneCount(p.Buffer.Document().CurrentLineBeforeCursor()),
+				istrings.RuneCountInString(p.Buffer.Document().CurrentLineBeforeCursor()),
 				p.renderer.col,
 				p.renderer.row,
 			)
@@ -114,7 +114,7 @@ var emacsKeyBindings = []KeyBind{
 	{
 		Key: AltRight,
 		Fn: func(p *Prompt) bool {
-			return p.CursorRight(
+			return p.CursorRightRunes(
 				p.Buffer.Document().FindRuneNumberUntilEndOfCurrentWord(),
 			)
 		},
@@ -130,7 +130,7 @@ var emacsKeyBindings = []KeyBind{
 	{
 		Key: AltLeft,
 		Fn: func(p *Prompt) bool {
-			return p.CursorLeft(
+			return p.CursorLeftRunes(
 				p.Buffer.Document().FindRuneNumberUntilStartOfPreviousWord(),
 			)
 		},
diff --git a/go.mod b/go.mod
index 0db5cac3..5d8cd258 100644
--- a/go.mod
+++ b/go.mod
@@ -12,4 +12,7 @@ require (
 	golang.org/x/sys v0.1.0
 )
 
-require github.com/mattn/go-isatty v0.0.12 // indirect
+require (
+	github.com/mattn/go-isatty v0.0.12 // indirect
+	github.com/rivo/uniseg v0.4.4 // indirect
+)
diff --git a/go.sum b/go.sum
index 8b177a46..03984c81 100644
--- a/go.sum
+++ b/go.sum
@@ -14,6 +14,8 @@ github.com/mattn/go-tty v0.0.3 h1:5OfyWorkyO7xP52Mq7tB36ajHDG5OHrmBGIS/DtakQI=
 github.com/mattn/go-tty v0.0.3/go.mod h1:ihxohKRERHTVzN+aSVRwACLCeqIoZAWpoICkkvrWyR0=
 github.com/pkg/term v1.2.0-beta.2 h1:L3y/h2jkuBVFdWiJvNfYfKmzcCnILw7mJWm2JQuMppw=
 github.com/pkg/term v1.2.0-beta.2/go.mod h1:E25nymQcrSllhX42Ok8MRm1+hyBdHY0dCeiKZ9jpNGw=
+github.com/rivo/uniseg v0.4.4 h1:8TfxU8dW6PdqD27gjM8MVNuicgxIjxpm4K7x4jp8sis=
+github.com/rivo/uniseg v0.4.4/go.mod h1:FN3SvrM+Zdj16jyLfmOkMNblXMcoc8DfTHruCPUcx88=
 golang.org/x/exp v0.0.0-20230626212559-97b1e661b5df h1:UA2aFVmmsIlefxMk29Dp2juaUSth8Pyn3Tq5Y5mJGME=
 golang.org/x/exp v0.0.0-20230626212559-97b1e661b5df/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
diff --git a/key_bind_func.go b/key_bind_func.go
index 21e203bd..59d4b499 100644
--- a/key_bind_func.go
+++ b/key_bind_func.go
@@ -7,13 +7,13 @@ import (
 // GoLineEnd Go to the End of the line
 func GoLineEnd(p *Prompt) bool {
 	x := []rune(p.Buffer.Document().TextAfterCursor())
-	return p.CursorRight(istrings.RuneNumber(len(x)))
+	return p.CursorRightRunes(istrings.RuneNumber(len(x)))
 }
 
 // GoLineBeginning Go to the beginning of the line
 func GoLineBeginning(p *Prompt) bool {
 	x := []rune(p.Buffer.Document().TextBeforeCursor())
-	return p.CursorLeft(istrings.RuneNumber(len(x)))
+	return p.CursorLeftRunes(istrings.RuneNumber(len(x)))
 }
 
 // DeleteChar Delete character under the cursor
@@ -40,7 +40,7 @@ func GoLeftChar(p *Prompt) bool {
 
 func DeleteWordBeforeCursor(p *Prompt) bool {
 	p.Buffer.DeleteBeforeCursor(
-		istrings.RuneCount(p.Buffer.Document().GetWordBeforeCursorWithSpace()),
+		istrings.RuneCountInString(p.Buffer.Document().GetWordBeforeCursorWithSpace()),
 		p.renderer.col,
 		p.renderer.row,
 	)
diff --git a/position.go b/position.go
index 138e9243..53e750d2 100644
--- a/position.go
+++ b/position.go
@@ -1,11 +1,8 @@
 package prompt
 
 import (
-	"io"
-	"strings"
-
 	istrings "github.com/elk-language/go-prompt/strings"
-	"github.com/mattn/go-runewidth"
+	"github.com/rivo/uniseg"
 )
 
 // Position stores the coordinates
@@ -48,49 +45,32 @@ func (p Position) Subtract(other Position) Position {
 // positionAtEndOfString calculates the position of the
 // p at the end of the given string.
 func positionAtEndOfStringLine(str string, columns istrings.Width, line int) Position {
-	return positionAtEndOfReaderLine(strings.NewReader(str), columns, line)
-}
-
-// positionAtEndOfString calculates the position
-// at the end of the given string.
-func positionAtEndOfString(str string, columns istrings.Width) Position {
-	return positionAtEndOfReader(strings.NewReader(str), columns)
-}
-
-// positionAtEndOfReader calculates the position
-// at the end of the given io.Reader.
-func positionAtEndOfReader(reader io.RuneReader, columns istrings.Width) Position {
 	var down int
 	var right istrings.Width
+	g := uniseg.NewGraphemes(str)
 
 charLoop:
-	for {
-		char, _, err := reader.ReadRune()
-		if err != nil {
-			break charLoop
-		}
+	for g.Next() {
+		runes := g.Runes()
 
-		switch char {
-		case '\r':
-			char, _, err := reader.ReadRune()
-			if err != nil {
+		if len(runes) == 1 && runes[0] == '\n' {
+			if down == line {
 				break charLoop
 			}
-
-			if char == '\n' {
-				down++
-				right = 0
-			}
-		case '\n':
 			down++
 			right = 0
-		default:
-			right += istrings.Width(runewidth.RuneWidth(char))
-			if right == columns {
-				right = 0
-				down++
+		}
+
+		right += istrings.Width(g.Width())
+		if right > columns {
+			if down == line {
+				right = columns - 1
+				break charLoop
 			}
+			right = istrings.Width(g.Width())
+			down++
 		}
+
 	}
 
 	return Position{
@@ -99,49 +79,26 @@ charLoop:
 	}
 }
 
-// positionAtEndOfReaderLine calculates the position
-// at the given line of the given io.Reader.
-func positionAtEndOfReaderLine(reader io.RuneReader, columns istrings.Width, line int) Position {
+// positionAtEndOfString calculates the position
+// at the end of the given string.
+func positionAtEndOfString(str string, columns istrings.Width) Position {
 	var down int
 	var right istrings.Width
+	g := uniseg.NewGraphemes(str)
 
-charLoop:
-	for {
-		char, _, err := reader.ReadRune()
-		if err != nil {
-			break charLoop
-		}
+	for g.Next() {
+		runes := g.Runes()
 
-		switch char {
-		case '\r':
-			char, _, err := reader.ReadRune()
-			if err != nil {
-				break charLoop
-			}
-
-			if char == '\n' {
-				if down == line {
-					break charLoop
-				}
-				down++
-				right = 0
-			}
-		case '\n':
-			if down == line {
-				break charLoop
-			}
+		if len(runes) == 1 && runes[0] == '\n' {
 			down++
 			right = 0
-		default:
-			right += istrings.Width(runewidth.RuneWidth(char))
-			if right > columns {
-				if down == line {
-					right = columns - 1
-					break charLoop
-				}
-				right = istrings.Width(runewidth.RuneWidth(char))
-				down++
-			}
+			continue
+		}
+
+		right += istrings.Width(g.Width())
+		if right == columns {
+			right = 0
+			down++
 		}
 	}
 
diff --git a/position_test.go b/position_test.go
index 0ea6dd31..6220bd26 100644
--- a/position_test.go
+++ b/position_test.go
@@ -40,6 +40,14 @@ func TestPositionAtEndOfString(t *testing.T) {
 				Y: 0,
 			},
 		},
+		"complex emoji": {
+			input:   "🙆🏿‍♂️",
+			columns: 20,
+			want: Position{
+				X: 2,
+				Y: 0,
+			},
+		},
 		"one-line fits in columns": {
 			input:   "foo bar",
 			columns: 20,
diff --git a/prompt.go b/prompt.go
index bebc1cfa..89b47e0a 100644
--- a/prompt.go
+++ b/prompt.go
@@ -2,6 +2,8 @@ package prompt
 
 import (
 	"bytes"
+	"fmt"
+	"log"
 	"os"
 	"strings"
 	"time"
@@ -138,14 +140,14 @@ func (p *Prompt) Run() {
 	}
 }
 
-// func Log(format string, a ...any) {
-// 	f, err := os.OpenFile("log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
-// 	if err != nil {
-// 		log.Fatalf("error opening file: %v", err)
-// 	}
-// 	defer f.Close()
-// 	fmt.Fprintf(f, format+"\n", a...)
-// }
+func Log(format string, a ...any) {
+	f, err := os.OpenFile("log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
+	if err != nil {
+		log.Fatalf("error opening file: %v", err)
+	}
+	defer f.Close()
+	fmt.Fprintf(f, format+"\n", a...)
+}
 
 func (p *Prompt) feed(b []byte) (shouldExit bool, rerender bool, userInput *UserInput) {
 	key := GetKey(b)
@@ -349,7 +351,7 @@ func (p *Prompt) updateSuggestions(fn func()) {
 	// delete the previous selection
 	if !newSelected {
 		p.Buffer.DeleteBeforeCursor(
-			istrings.RuneCount(prevSuggestion.Text)-(prevEnd-prevStart),
+			istrings.RuneCountInString(prevSuggestion.Text)-(prevEnd-prevStart),
 			cols,
 			rows,
 		)
@@ -358,7 +360,7 @@ func (p *Prompt) updateSuggestions(fn func()) {
 
 	// delete previous selection and render the new one
 	p.Buffer.DeleteBeforeCursor(
-		istrings.RuneCount(prevSuggestion.Text),
+		istrings.RuneCountInString(prevSuggestion.Text),
 		cols,
 		rows,
 	)
@@ -518,33 +520,40 @@ func (p *Prompt) setup() {
 	p.renderer.UpdateWinSize(p.reader.GetWinSize())
 }
 
-// Move to the left on the current line.
+// Move to the left on the current line  by the given amount of graphemes (visible characters).
 // Returns true when the view should be rerendered.
-func (p *Prompt) CursorLeft(count istrings.RuneNumber) bool {
-	b := p.Buffer
-	cols := p.renderer.UserInputColumns()
-	previousCursor := b.DisplayCursorPosition(cols)
+func (p *Prompt) CursorLeft(count istrings.GraphemeNumber) bool {
+	return promptCursorHorizontalMove(p, p.Buffer.CursorLeft, count)
+}
 
-	rerender := p.Buffer.CursorLeft(count, cols, p.renderer.row) || p.completionReset || len(p.completion.tmp) > 0
-	if rerender {
-		return true
-	}
+// Move to the left on the current line by the given amount of runes.
+// Returns true when the view should be rerendered.
+func (p *Prompt) CursorLeftRunes(count istrings.RuneNumber) bool {
+	return promptCursorHorizontalMove(p, p.Buffer.CursorLeftRunes, count)
+}
 
-	newCursor := b.DisplayCursorPosition(cols)
-	p.renderer.previousCursor = newCursor
-	p.renderer.move(previousCursor, newCursor)
-	p.renderer.flush()
-	return false
+// Move the cursor to the right on the current line by the given amount of graphemes (visible characters).
+// Returns true when the view should be rerendered.
+func (p *Prompt) CursorRight(count istrings.GraphemeNumber) bool {
+	return promptCursorHorizontalMove(p, p.Buffer.CursorRight, count)
 }
 
-// Move the cursor to the right on the current line.
+// Move the cursor to the right on the current line by the given amount of runes.
+// Returns true when the view should be rerendered.
+func (p *Prompt) CursorRightRunes(count istrings.RuneNumber) bool {
+	return promptCursorHorizontalMove(p, p.Buffer.CursorRightRunes, count)
+}
+
+type horizontalCursorModifier[CountT ~int] func(CountT, istrings.Width, int) bool
+
+// Move to the left or right on the current line.
 // Returns true when the view should be rerendered.
-func (p *Prompt) CursorRight(count istrings.RuneNumber) bool {
+func promptCursorHorizontalMove[CountT ~int](p *Prompt, modifierFunc horizontalCursorModifier[CountT], count CountT) bool {
 	b := p.Buffer
 	cols := p.renderer.UserInputColumns()
 	previousCursor := b.DisplayCursorPosition(cols)
 
-	rerender := p.Buffer.CursorRight(count, cols, p.renderer.row) || p.completionReset || len(p.completion.tmp) > 0
+	rerender := modifierFunc(count, cols, p.renderer.row) || p.completionReset || len(p.completion.tmp) > 0
 	if rerender {
 		return true
 	}
diff --git a/strings/strings.go b/strings/strings.go
index 8523faf8..0781b02a 100644
--- a/strings/strings.go
+++ b/strings/strings.go
@@ -4,6 +4,7 @@ import (
 	"unicode/utf8"
 
 	"github.com/mattn/go-runewidth"
+	"github.com/rivo/uniseg"
 )
 
 // Get the length of the string in bytes.
@@ -12,13 +13,27 @@ func Len(s string) ByteNumber {
 }
 
 // Get the length of the string in runes.
-func RuneCount(s string) RuneNumber {
+func RuneCountInString(s string) RuneNumber {
 	return RuneNumber(utf8.RuneCountInString(s))
 }
 
-// Get the width of the string (how many columns it takes upt in the terminal).
-func GetWidth(s string) Width {
-	return Width(runewidth.StringWidth(s))
+// Get the length of the byte slice in runes.
+func RuneCount(b []byte) RuneNumber {
+	return RuneNumber(utf8.RuneCount(b))
+}
+
+// Returns the number of horizontal cells needed to print the given
+// text. It splits the text into its grapheme clusters, calculates each
+// cluster's width, and adds them up to a total.
+func GetWidth(text string) Width {
+	return Width(uniseg.StringWidth(text))
+}
+
+// Returns the number of horizontal cells needed to print the given
+// text. It splits the text into its grapheme clusters, calculates each
+// cluster's width, and adds them up to a total.
+func GraphemeCount(text string) GraphemeNumber {
+	return GraphemeNumber(uniseg.GraphemeClusterCount(text))
 }
 
 // Get the width of the rune (how many columns it takes upt in the terminal).
diff --git a/strings/strings_test.go b/strings/strings_test.go
index 8266054c..849cb2fc 100644
--- a/strings/strings_test.go
+++ b/strings/strings_test.go
@@ -2,10 +2,41 @@ package strings_test
 
 import (
 	"fmt"
+	"testing"
 
 	"github.com/elk-language/go-prompt/strings"
 )
 
+func TestGetWidth(t *testing.T) {
+	tests := []struct {
+		in   string
+		want strings.Width
+	}{
+		{
+			in:   "foo",
+			want: 3,
+		},
+		{
+			in:   "🇵🇱",
+			want: 2,
+		},
+		{
+			in:   "🙆🏿‍♂️",
+			want: 2,
+		},
+		{
+			in:   "日本語",
+			want: 6,
+		},
+	}
+
+	for _, tc := range tests {
+		if got := strings.GetWidth(tc.in); got != tc.want {
+			t.Errorf("Should be %#v, but got %#v, for %#v", tc.want, got, tc.in)
+		}
+	}
+}
+
 func ExampleIndexNotByte() {
 	fmt.Println(strings.IndexNotByte("golang", 'g'))
 	fmt.Println(strings.IndexNotByte("golang", 'x'))
diff --git a/strings/units.go b/strings/units.go
index 2f74a0e9..e34b247b 100644
--- a/strings/units.go
+++ b/strings/units.go
@@ -8,6 +8,10 @@ type ByteNumber int
 // of runes in a string, array or slice.
 type RuneNumber int
 
+// Numeric type that represents the amount
+// of grapheme clusters in a string, array or slice.
+type GraphemeNumber int
+
 // Numeric type that represents the visible
 // width of characters in a string as seen in a terminal emulator.
 type Width int