package readline import ( "fmt" "github.com/emirpasic/gods/lists/arraylist" "golang.org/x/term" ) type Buffer struct { Pos int Buf *arraylist.List Prompt *Prompt LineWidth int Width int Height int } func NewBuffer(prompt *Prompt) (*Buffer, error) { width, height, err := term.GetSize(0) if err != nil { fmt.Println("Error getting size:", err) return nil, err } lwidth := width - len(prompt.Prompt) if prompt.UseAlt { lwidth = width - len(prompt.AltPrompt) } b := &Buffer{ Pos: 0, Buf: arraylist.New(), Prompt: prompt, Width: width, Height: height, LineWidth: lwidth, } return b, nil } func (b *Buffer) MoveLeft() { if b.Pos > 0 { if b.Pos%b.LineWidth == 0 { fmt.Printf(CursorUp + CursorBOL + cursorRightN(b.Width)) } else { fmt.Print(CursorLeft) } b.Pos -= 1 } } func (b *Buffer) MoveLeftWord() { if b.Pos > 0 { var foundNonspace bool for { v, _ := b.Buf.Get(b.Pos - 1) if v == ' ' { if foundNonspace { break } } else { foundNonspace = true } b.MoveLeft() if b.Pos == 0 { break } } } } func (b *Buffer) MoveRight() { if b.Pos < b.Size() { b.Pos += 1 if b.Pos%b.LineWidth == 0 { fmt.Printf(CursorDown + CursorBOL + cursorRightN(b.PromptSize())) } else { fmt.Print(CursorRight) } } } func (b *Buffer) MoveRightWord() { if b.Pos < b.Size() { for { b.MoveRight() v, _ := b.Buf.Get(b.Pos) if v == ' ' { break } if b.Pos == b.Size() { break } } } } func (b *Buffer) MoveToStart() { if b.Pos > 0 { currLine := b.Pos / b.LineWidth if currLine > 0 { for cnt := 0; cnt < currLine; cnt++ { fmt.Print(CursorUp) } } fmt.Printf(CursorBOL + cursorRightN(b.PromptSize())) b.Pos = 0 } } func (b *Buffer) MoveToEnd() { if b.Pos < b.Size() { currLine := b.Pos / b.LineWidth totalLines := b.Size() / b.LineWidth if currLine < totalLines { for cnt := 0; cnt < totalLines-currLine; cnt++ { fmt.Print(CursorDown) } remainder := b.Size() % b.LineWidth fmt.Printf(CursorBOL + cursorRightN(b.PromptSize()+remainder)) } else { fmt.Print(cursorRightN(b.Size() - b.Pos)) } b.Pos = b.Size() } } func (b *Buffer) Size() int { return b.Buf.Size() } func min(n, m int) int { if n > m { return m } return n } func (b *Buffer) PromptSize() int { if b.Prompt.UseAlt { return len(b.Prompt.AltPrompt) } return len(b.Prompt.Prompt) } func (b *Buffer) Add(r rune) { if b.Pos == b.Buf.Size() { fmt.Printf("%c", r) b.Buf.Add(r) b.Pos += 1 if b.Pos > 0 && b.Pos%b.LineWidth == 0 { fmt.Printf("\n%s", b.Prompt.AltPrompt) } } else { fmt.Printf("%c", r) b.Buf.Insert(b.Pos, r) b.Pos += 1 if b.Pos > 0 && b.Pos%b.LineWidth == 0 { fmt.Printf("\n%s", b.Prompt.AltPrompt) } b.drawRemaining() } } func (b *Buffer) drawRemaining() { var place int remainingText := b.StringN(b.Pos) if b.Pos > 0 { place = b.Pos % b.LineWidth } fmt.Print(CursorHide) // render the rest of the current line currLine := remainingText[:min(b.LineWidth-place, len(remainingText))] if len(currLine) > 0 { fmt.Printf(ClearToEOL + currLine) fmt.Print(cursorLeftN(len(currLine))) } else { fmt.Print(ClearToEOL) } // render the other lines if len(remainingText) > len(currLine) { remaining := []rune(remainingText[len(currLine):]) var totalLines int for i, c := range remaining { if i%b.LineWidth == 0 { fmt.Printf("\n%s", b.Prompt.AltPrompt) totalLines += 1 } fmt.Printf("%c", c) } fmt.Print(ClearToEOL) fmt.Print(cursorUpN(totalLines)) fmt.Printf(CursorBOL + cursorRightN(b.Width-len(currLine))) } fmt.Print(CursorShow) } func (b *Buffer) Remove() { if b.Buf.Size() > 0 && b.Pos > 0 { if b.Pos%b.LineWidth == 0 { // if the user backspaces over the word boundary, do this magic to clear the line // and move to the end of the previous line fmt.Printf(CursorBOL + ClearToEOL) fmt.Printf(CursorUp + CursorBOL + cursorRightN(b.Width) + " " + CursorLeft) } else { fmt.Printf(CursorLeft + " " + CursorLeft) } var eraseExtraLine bool if (b.Size()-1)%b.LineWidth == 0 { eraseExtraLine = true } b.Pos -= 1 b.Buf.Remove(b.Pos) if b.Pos < b.Size() { b.drawRemaining() // this erases a line which is left over when backspacing in the middle of a line and there // are trailing characters which go over the line width boundary if eraseExtraLine { remainingLines := (b.Size() - b.Pos) / b.LineWidth fmt.Printf(cursorDownN(remainingLines+1) + CursorBOL + ClearToEOL) place := b.Pos % b.LineWidth fmt.Printf(cursorUpN(remainingLines+1) + cursorRightN(place+len(b.Prompt.Prompt))) } } } } func (b *Buffer) Delete() { if b.Size() > 0 && b.Pos < b.Size() { b.Buf.Remove(b.Pos) b.drawRemaining() if b.Size()%b.LineWidth == 0 { if b.Pos != b.Size() { remainingLines := (b.Size() - b.Pos) / b.LineWidth fmt.Printf(cursorDownN(remainingLines) + CursorBOL + ClearToEOL) place := b.Pos % b.LineWidth fmt.Printf(cursorUpN(remainingLines) + cursorRightN(place+len(b.Prompt.Prompt))) } } } } func (b *Buffer) DeleteBefore() { if b.Pos > 0 { for cnt := b.Pos - 1; cnt >= 0; cnt-- { b.Remove() } } } func (b *Buffer) DeleteRemaining() { if b.Size() > 0 && b.Pos < b.Size() { charsToDel := b.Size() - b.Pos for cnt := 0; cnt < charsToDel; cnt++ { b.Delete() } } } func (b *Buffer) DeleteWord() { if b.Buf.Size() > 0 && b.Pos > 0 { var foundNonspace bool for { v, _ := b.Buf.Get(b.Pos - 1) if v == ' ' { if !foundNonspace { b.Remove() } else { break } } else { foundNonspace = true b.Remove() } if b.Pos == 0 { break } } } } func (b *Buffer) ClearScreen() { fmt.Printf(ClearScreen + CursorReset + b.Prompt.Prompt) if b.IsEmpty() { ph := b.Prompt.Placeholder fmt.Printf(ColorGrey + ph + cursorLeftN(len(ph)) + ColorDefault) } else { currPos := b.Pos b.Pos = 0 b.drawRemaining() fmt.Printf(CursorReset + cursorRightN(len(b.Prompt.Prompt))) if currPos > 0 { targetLine := currPos / b.LineWidth if targetLine > 0 { for cnt := 0; cnt < targetLine; cnt++ { fmt.Print(CursorDown) } } remainder := currPos % b.LineWidth if remainder > 0 { fmt.Print(cursorRightN(remainder)) } if currPos%b.LineWidth == 0 { fmt.Printf(CursorBOL + b.Prompt.AltPrompt) } } b.Pos = currPos } } func (b *Buffer) IsEmpty() bool { return b.Buf.Empty() } func (b *Buffer) Replace(r []rune) { b.Pos = 0 b.Buf.Clear() fmt.Printf(ClearLine + CursorBOL + b.Prompt.Prompt) for _, c := range r { b.Add(c) } } func (b *Buffer) String() string { return b.StringN(0) } func (b *Buffer) StringN(n int) string { return b.StringNM(n, 0) } func (b *Buffer) StringNM(n, m int) string { var s string if m == 0 { m = b.Size() } for cnt := n; cnt < m; cnt++ { c, _ := b.Buf.Get(cnt) s += string(c.(rune)) } return s } func cursorLeftN(n int) string { return fmt.Sprintf(CursorLeftN, n) } func cursorRightN(n int) string { return fmt.Sprintf(CursorRightN, n) } func cursorUpN(n int) string { return fmt.Sprintf(CursorUpN, n) } func cursorDownN(n int) string { return fmt.Sprintf(CursorDownN, n) }