Render using a scrolling buffer

CHANGELOG.md

@@ -55,7 +55,6 @@ This release aims to make the code a bit cleaner, fix a couple of bugs and provi
 - Rename `prompt.OptionPrefixBackgroundColor` to `prompt.WithPrefixBackgroundColor`
 - Rename `prompt.OptionInputTextColor` to `prompt.WithInputTextColor`
 - Rename `prompt.OptionInputBGColor` to `prompt.WithInputBGColor`
-- Rename `prompt.OptionPreviewSuggestionTextColor` to `prompt.WithPreviewSuggestionTextColor`
 - Rename `prompt.OptionSuggestionTextColor` to `prompt.WithSuggestionTextColor`
 - Rename `prompt.OptionSuggestionBGColor` to `prompt.WithSuggestionBGColor`
 - Rename `prompt.OptionSelectedSuggestionTextColor` to `prompt.WithSelectedSuggestionTextColor`
@@ -75,6 +74,8 @@ This release aims to make the code a bit cleaner, fix a couple of bugs and provi
 - Rename `prompt.OptionShowCompletionAtStart` to `prompt.WithShowCompletionAtStart`
 - Rename `prompt.OptionBreakLineCallback` to `prompt.WithBreakLineCallback`
 - Rename `prompt.OptionExitChecker` to `prompt.WithExitChecker`
+- Change the signature of `Completer` from `func(Document) []Suggest` to `func(Document) (suggestions []Suggest, startChar, endChar istrings.RuneNumber)`
+- Change the signature of `KeyBindFunc` from `func(*Buffer)` to `func(p *Prompt) (rerender bool)`
 
 ### Fixed
 
@@ -86,7 +87,8 @@ This release aims to make the code a bit cleaner, fix a couple of bugs and provi
 ### Removed
 
 - `prompt.SwitchKeyBindMode`
-
+- `prompt.OptionPreviewSuggestionTextColor`
+- `prompt.OptionPreviewSuggestionBGColor`
 
 ## [0.2.6] - 2021-03-03
 

_example/even-lexer/main.go

@@ -2,9 +2,10 @@ package main
 
 import (
 	"fmt"
-	"strings"
+	"unicode/utf8"
 
 	"github.com/elk-language/go-prompt"
+	"github.com/elk-language/go-prompt/strings"
 )
 
 func main() {
@@ -19,17 +20,16 @@ func main() {
 func lexer(line string) []prompt.Token {
 	var elements []prompt.Token
 
-	strArr := strings.Split(line, "")
-
-	for i, value := range strArr {
+	for i, value := range line {
 		var color prompt.Color
 		// every even char must be green.
 		if i%2 == 0 {
 			color = prompt.Green
 		} else {
 			color = prompt.White
 		}
-		element := prompt.NewSimpleToken(color, value)
+		lastByteIndex := strings.ByteNumber(i + utf8.RuneLen(value) - 1)
+		element := prompt.NewSimpleToken(color, lastByteIndex)
 
 		elements = append(elements, element)
 	}

_example/exec-command/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"os/exec"
 
@@ -9,6 +10,7 @@ import (
 
 func executor(t string) {
 	if t != "bash" {
+		fmt.Println("Sorry, I don't understand.")
 		return
 	}
 
@@ -19,16 +21,9 @@ func executor(t string) {
 	cmd.Run()
 }
 
-func completer(t prompt.Document) []prompt.Suggest {
-	return []prompt.Suggest{
-		{Text: "bash"},
-	}
-}
-
 func main() {
 	p := prompt.New(
 		executor,
-		prompt.WithCompleter(completer),
 	)
 	p.Run()
 }

_example/http-prompt/main.go

@@ -11,6 +11,7 @@ import (
 	"strings"
 
 	prompt "github.com/elk-language/go-prompt"
+	istrings "github.com/elk-language/go-prompt/strings"
 )
 
 type RequestContext struct {
@@ -157,12 +158,14 @@ func executor(in string) {
 	}
 }
 
-func completer(in prompt.Document) []prompt.Suggest {
+func completer(in prompt.Document) ([]prompt.Suggest, istrings.RuneNumber, istrings.RuneNumber) {
+	endIndex := in.CurrentRuneIndex()
 	w := in.GetWordBeforeCursor()
 	if w == "" {
-		return []prompt.Suggest{}
+		return []prompt.Suggest{}, 0, 0
 	}
-	return prompt.FilterHasPrefix(suggestions, w, true)
+	startIndex := endIndex - istrings.RuneCount(w)
+	return prompt.FilterHasPrefix(suggestions, w, true), startIndex, endIndex
 }
 
 func main() {

_example/live-prefix/main.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	prompt "github.com/elk-language/go-prompt"
+	istrings "github.com/elk-language/go-prompt/strings"
 )
 
 var LivePrefix string = ">>> "
@@ -17,14 +18,18 @@ func executor(in string) {
 	LivePrefix = in + "> "
 }
 
-func completer(in prompt.Document) []prompt.Suggest {
+func completer(in prompt.Document) ([]prompt.Suggest, istrings.RuneNumber, istrings.RuneNumber) {
+	endIndex := in.CurrentRuneIndex()
+	w := in.GetWordBeforeCursor()
+	startIndex := endIndex - istrings.RuneCount(w)
+
 	s := []prompt.Suggest{
 		{Text: "users", Description: "Store the username and age"},
 		{Text: "articles", Description: "Store the article text posted by user"},
 		{Text: "comments", Description: "Store the text commented to articles"},
 		{Text: "groups", Description: "Combine users with specific rules"},
 	}
-	return prompt.FilterHasPrefix(s, in.GetWordBeforeCursor(), true)
+	return prompt.FilterHasPrefix(s, w, true), startIndex, endIndex
 }
 
 func changeLivePrefix() string {

buffer.go

@@ -11,6 +11,7 @@ import (
 type Buffer struct {
 	workingLines   []string // The working lines. Similar to history
 	workingIndex   int      // index of the current line
+	startLine      int      // Line number of the first visible line in the terminal (0-indexed)
 	cursorPosition istrings.RuneNumber
 	cacheDocument  *Document
 	lastKeyStroke  Key
@@ -41,8 +42,18 @@ func (b *Buffer) DisplayCursorPosition(columns istrings.Width) Position {
 	return b.Document().DisplayCursorPosition(columns)
 }
 
-// InsertText insert string from current line.
-func (b *Buffer) InsertText(text string, overwrite bool, moveCursor bool) {
+// Insert string into the buffer and move the cursor.
+func (b *Buffer) InsertTextMoveCursor(text string, columns istrings.Width, rows int, overwrite bool) {
+	b.insertText(text, columns, rows, overwrite, true)
+}
+
+// Insert string into the buffer without moving the cursor.
+func (b *Buffer) InsertText(text string, overwrite bool) {
+	b.insertText(text, 0, 0, overwrite, false)
+}
+
+// insertText insert string from current line.
+func (b *Buffer) insertText(text string, columns istrings.Width, rows int, overwrite bool, moveCursor bool) {
 	currentTextRunes := []rune(b.Text())
 	cursor := b.cursorPosition
 
@@ -54,22 +65,52 @@ func (b *Buffer) InsertText(text string, overwrite bool, moveCursor bool) {
 		if i := strings.IndexAny(overwritten, "\n"); i != -1 {
 			overwritten = overwritten[:i]
 		}
-		b.setText(string(currentTextRunes[:cursor]) + text + string(currentTextRunes[cursor+istrings.RuneCount(overwritten):]))
+		b.setText(
+			string(currentTextRunes[:cursor])+text+string(currentTextRunes[cursor+istrings.RuneCount(overwritten):]),
+			columns,
+			rows,
+		)
 	} else {
-		b.setText(string(currentTextRunes[:cursor]) + text + string(currentTextRunes[cursor:]))
+		b.setText(
+			string(currentTextRunes[:cursor])+text+string(currentTextRunes[cursor:]),
+			columns,
+			rows,
+		)
 	}
 
 	if moveCursor {
 		b.cursorPosition += istrings.RuneCount(text)
+		b.RecalculateStartLine(columns, rows)
+	}
+}
+
+func (b *Buffer) ResetStartLine() {
+	b.startLine = 0
+}
+
+// Calculates the startLine once again and returns true when it's been changed.
+func (b *Buffer) RecalculateStartLine(columns istrings.Width, rows int) bool {
+	origStartLine := b.startLine
+	pos := b.DisplayCursorPosition(columns)
+	if pos.Y > b.startLine+rows-1 {
+		b.startLine = pos.Y - rows + 1
+	} else if pos.Y < b.startLine {
+		b.startLine = pos.Y
+	}
+
+	if b.startLine < 0 {
+		b.startLine = 0
 	}
+	return origStartLine != b.startLine
 }
 
 // SetText method to set text and update cursorPosition.
 // (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) {
+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")
 	b.workingLines[b.workingIndex] = text
+	b.RecalculateStartLine(col, row)
 }
 
 // Set cursor position. Return whether it changed.
@@ -81,40 +122,49 @@ func (b *Buffer) setCursorPosition(p istrings.RuneNumber) {
 	}
 }
 
-func (b *Buffer) setDocument(d *Document) {
+func (b *Buffer) setDocument(d *Document, columns istrings.Width, rows int) {
 	b.cacheDocument = d
 	b.setCursorPosition(d.cursorPosition) // Call before setText because setText check the relation between cursorPosition and line length.
-	b.setText(d.Text)
+	b.setText(d.Text, columns, rows)
+	b.RecalculateStartLine(columns, rows)
 }
 
-// CursorLeft move to left on the current line.
-func (b *Buffer) CursorLeft(count istrings.RuneNumber) {
+// Move to the left on the current line.
+// 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
+	return b.RecalculateStartLine(columns, rows)
 }
 
-// CursorRight move to right on the current line.
-func (b *Buffer) CursorRight(count istrings.RuneNumber) {
+// Move to the right on the current line.
+// 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
+	return b.RecalculateStartLine(columns, rows)
 }
 
 // CursorUp move cursor to the previous line.
 // (for multi-line edit).
-func (b *Buffer) CursorUp(count int) {
+// Returns true when the view should be rerendered.
+func (b *Buffer) CursorUp(count int, columns istrings.Width, rows int) bool {
 	orig := b.Document().CursorPositionCol()
 	b.cursorPosition += b.Document().GetCursorUpPosition(count, orig)
+	return b.RecalculateStartLine(columns, rows)
 }
 
 // CursorDown move cursor to the next line.
 // (for multi-line edit).
-func (b *Buffer) CursorDown(count int) {
+// Returns true when the view should be rerendered.
+func (b *Buffer) CursorDown(count int, columns istrings.Width, rows int) bool {
 	orig := b.Document().CursorPositionCol()
 	b.cursorPosition += b.Document().GetCursorDownPosition(count, orig)
+	return b.RecalculateStartLine(columns, rows)
 }
 
 // DeleteBeforeCursor delete specified number of characters before cursor and return the deleted text.
-func (b *Buffer) DeleteBeforeCursor(count istrings.RuneNumber) (deleted string) {
+func (b *Buffer) DeleteBeforeCursor(count istrings.RuneNumber, columns istrings.Width, rows int) (deleted string) {
 	debug.Assert(count >= 0, "count should be positive")
 	r := []rune(b.Text())
 
@@ -127,28 +177,32 @@ func (b *Buffer) DeleteBeforeCursor(count istrings.RuneNumber) (deleted string)
 		b.setDocument(&Document{
 			Text:           string(r[:start]) + string(r[b.cursorPosition:]),
 			cursorPosition: b.cursorPosition - istrings.RuneNumber(len([]rune(deleted))),
-		})
+		}, columns, rows)
 	}
 	return
 }
 
 // NewLine means CR.
-func (b *Buffer) NewLine(copyMargin bool) {
+func (b *Buffer) NewLine(columns istrings.Width, rows int, copyMargin bool) {
 	if copyMargin {
-		b.InsertText("\n"+b.Document().leadingWhitespaceInCurrentLine(), false, true)
+		b.InsertTextMoveCursor("\n"+b.Document().leadingWhitespaceInCurrentLine(), columns, rows, false)
 	} else {
-		b.InsertText("\n", false, true)
+		b.InsertTextMoveCursor("\n", columns, rows, false)
 	}
 }
 
 // Delete specified number of characters and Return the deleted text.
-func (b *Buffer) Delete(count istrings.RuneNumber) string {
+func (b *Buffer) Delete(count istrings.RuneNumber, col istrings.Width, row int) string {
 	r := []rune(b.Text())
 	if b.cursorPosition < istrings.RuneNumber(len(r)) {
 		textAfterCursor := b.Document().TextAfterCursor()
 		textAfterCursorRunes := []rune(textAfterCursor)
 		deletedRunes := textAfterCursorRunes[:count]
-		b.setText(string(r[:b.cursorPosition]) + string(r[b.cursorPosition+istrings.RuneNumber(len(deletedRunes)):]))
+		b.setText(
+			string(r[:b.cursorPosition])+string(r[b.cursorPosition+istrings.RuneNumber(len(deletedRunes)):]),
+			col,
+			row,
+		)
 
 		deleted := string(deletedRunes)
 		return deleted
@@ -158,21 +212,29 @@ func (b *Buffer) Delete(count istrings.RuneNumber) string {
 }
 
 // JoinNextLine joins the next line to the current one by deleting the line ending after the current line.
-func (b *Buffer) JoinNextLine(separator string) {
+func (b *Buffer) JoinNextLine(separator string, col istrings.Width, row int) {
 	if !b.Document().OnLastLine() {
 		b.cursorPosition += b.Document().GetEndOfLinePosition()
-		b.Delete(1)
+		b.Delete(1, col, row)
 		// Remove spaces
-		b.setText(b.Document().TextBeforeCursor() + separator + strings.TrimLeft(b.Document().TextAfterCursor(), " "))
+		b.setText(
+			b.Document().TextBeforeCursor()+separator+strings.TrimLeft(b.Document().TextAfterCursor(), " "),
+			col,
+			row,
+		)
 	}
 }
 
 // SwapCharactersBeforeCursor swaps the last two characters before the cursor.
-func (b *Buffer) SwapCharactersBeforeCursor() {
+func (b *Buffer) SwapCharactersBeforeCursor(col istrings.Width, row int) {
 	if b.cursorPosition >= 2 {
 		x := b.Text()[b.cursorPosition-2 : b.cursorPosition-1]
 		y := b.Text()[b.cursorPosition-1 : b.cursorPosition]
-		b.setText(b.Text()[:b.cursorPosition-2] + y + x + b.Text()[b.cursorPosition:])
+		b.setText(
+			b.Text()[:b.cursorPosition-2]+y+x+b.Text()[b.cursorPosition:],
+			col,
+			row,
+		)
 	}
 }
 
@@ -181,6 +243,7 @@ func NewBuffer() (b *Buffer) {
 	b = &Buffer{
 		workingLines: []string{""},
 		workingIndex: 0,
+		startLine:    0,
 	}
 	return
 }