294 lines
5.8 KiB
Go
294 lines
5.8 KiB
Go
package qline
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// qline is a line input library for terminals that utilize
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// vt100 compatible escape sequences
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//
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// Copyright © 2021 Brian Evans
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//
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// Permission is hereby granted, free of charge, to any
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// person obtaining a copy of this software and associated
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// documentation files (the “Software”), to deal in the
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// Software without restriction, including without
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// limitation the rights to use, copy, modify, merge,
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// publish, distribute, sublicense, and/or sell copies of
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// the Software, and to permit persons to whom the Software
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// is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice
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// shall be included in all copies or substantial portions
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// of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
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// KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
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// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
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// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
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// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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// CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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// IN THE SOFTWARE.
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import (
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"bufio"
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"fmt"
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"os"
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"strings"
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"tildegit.org/sloum/swim/termios"
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)
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const (
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UpArrow rune = iota - 20
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DownArrow
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LeftArrow
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RightArrow
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Delete
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Home
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End
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PageUp
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PageDown
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Escape rune = 27
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NewLine rune = 10
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CarriageReturn rune = 13
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BackSpace rune = 127
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)
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var (
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width int
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)
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type buffer struct {
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buf []rune
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cursor int
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maxWidth int
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offset int
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cursorStart int
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prompt string
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}
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func GetInput(prompt string, content string) string {
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// termios.SetCharMode()
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cols, _ := termios.GetWindowSize()
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b := buffer{make([]rune, 0, (len(content)+1)*2), 0, cols-len(prompt), 0, 0, prompt}
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fmt.Print(prompt)
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fmt.Print("\033[6n")
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var ch rune
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var err error
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reader := bufio.NewReader(os.Stdin)
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for {
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ch, err = readKey(reader)
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if err != nil && err.Error() == "response" {
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b.cursorStart = int(ch)
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b.maxWidth = cols - b.cursorStart
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b.seedContent(content)
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b.printBuf()
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} else if err != nil {
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continue
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}
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if ch == CarriageReturn || ch == NewLine {
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break
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}
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if isControl(ch) {
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b.controlInput(ch)
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} else {
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b.addChar(ch, true)
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}
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}
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return b.string()
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}
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func (lb buffer) string() string {
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return string(lb.buf)
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}
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func (lb *buffer) deleteChar() {
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if lb.cursor == len(lb.buf) {
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return
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} else if lb.cursor == len(lb.buf)-1 {
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lb.buf = lb.buf[:len(lb.buf)-1]
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} else {
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lb.buf = append(lb.buf[:lb.cursor], lb.buf[lb.cursor+1:]...)
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}
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if lb.offset > 0 {
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lb.offset--
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}
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}
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func (lb *buffer) addChar(c rune, echo bool) {
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if c < 9 || (c > 10 && c < 13) || (c > 13 && c < 32) {
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return
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}
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if lb.cursor == len(lb.buf) {
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lb.buf = append(lb.buf, c)
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lb.cursor++
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} else {
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lb.buf = append(lb.buf[:lb.cursor+1], lb.buf[lb.cursor:]...)
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lb.buf[lb.cursor] = c
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lb.cursor++
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}
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if lb.cursor - lb.offset > lb.maxWidth {
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lb.offset++
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}
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if echo {
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lb.printBuf()
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}
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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func (lb buffer) printBuf() {
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out := lb.buf[lb.offset:min(len(lb.buf), lb.offset+lb.maxWidth)]
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fmt.Printf("\r%s%s\033[0K\r\033[%dC", lb.prompt, string(out), lb.cursor - lb.offset + len(lb.prompt))
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}
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func (lb *buffer) controlInput(c rune) {
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switch c {
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case Delete:
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lb.deleteChar()
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case BackSpace:
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if lb.cursor > 0 {
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lb.cursor--
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lb.deleteChar()
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}
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case LeftArrow:
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if lb.offset > 0 && lb.cursor - lb.offset == 0 {
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lb.offset--
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}
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if lb.cursor > 0 {
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lb.cursor--
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}
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case RightArrow:
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// This is still mildly funky, but works enough
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for ;lb.cursor - lb.offset >= lb.maxWidth && lb.cursor < len(lb.buf); {
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lb.offset++
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}
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if lb.cursor < len(lb.buf) {
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lb.cursor++
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}
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case Home:
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lb.offset = 0
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lb.cursor = 0
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case End:
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lb.cursor = len(lb.buf)
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lb.offset = max(lb.cursor - lb.maxWidth, 0)
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}
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lb.printBuf()
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}
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func (lb *buffer) seedContent(s string) {
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for _, r := range s {
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lb.addChar(r, false)
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}
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}
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func parseCursorPosition(esc string) (int, int, error) {
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var row, col int
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r := strings.NewReader(esc)
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_, err := fmt.Fscanf(r, "\033[%d;%dR", &row, &col)
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return row, col, err
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}
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func readKey(reader *bufio.Reader) (rune, error) {
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char, _, err := reader.ReadRune()
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if err != nil {
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return 0, err
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}
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avail := reader.Buffered()
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if char == Escape && avail > 0 {
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var b strings.Builder
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b.WriteRune(27)
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for ; avail > 0; avail-- {
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c, _, e := reader.ReadRune()
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if e != nil {
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break
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}
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b.WriteRune(c)
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}
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escSeq := b.String()
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switch true {
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case escSeq == "\033[A":
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char = UpArrow
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case escSeq == "\033[B":
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char = DownArrow
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case escSeq == "\033[C":
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char = RightArrow
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case escSeq == "\033[D":
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char = LeftArrow
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case escSeq == "\033[5~":
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char = PageUp
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case escSeq == "\033[6~":
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char = PageDown
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case isHomeKey(escSeq):
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char = Home
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case isEndKey(escSeq):
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char = End
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case isDeleteKey(escSeq):
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char = Delete
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case escSeq[len(escSeq)-1] == 'R':
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// This is a request for cursor position
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_, cols, err := parseCursorPosition(escSeq)
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if err == nil {
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err = fmt.Errorf("response")
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}
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return rune(cols), err
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}
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}
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return char, nil
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}
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func isControl(c rune) bool {
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switch c {
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case UpArrow, DownArrow, RightArrow, LeftArrow, PageUp, PageDown, Home, End, Delete, BackSpace, CarriageReturn, NewLine, Escape:
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return true
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default:
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return false
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}
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}
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func isDeleteKey(seq string) bool {
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switch seq {
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case "\033[3~", "\033[P":
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return true
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default:
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return false
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}
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}
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func isHomeKey(seq string) bool {
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switch seq {
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case "\033[1~", "\033[7~", "\033[H", "\033OH":
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return true
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default:
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return false
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}
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}
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func isEndKey(seq string) bool {
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switch seq {
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case "\033[4~", "\033[8~", "\033[F", "\033OF":
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return true
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default:
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return false
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}
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}
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