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key.go
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key.go
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package vt100
import (
"errors"
"fmt"
"io"
"strconv"
"time"
"unicode"
"unicode/utf8"
"github.com/pkg/term"
)
var (
defaultTimeout = 2 * time.Millisecond
lastKey int
)
// Key codes for 3-byte sequences (arrows, Home, End)
var keyCodeLookup = map[[3]byte]int{
{27, 91, 65}: 253, // Up Arrow
{27, 91, 66}: 255, // Down Arrow
{27, 91, 67}: 254, // Right Arrow
{27, 91, 68}: 252, // Left Arrow
{27, 91, 'H'}: 1, // Home (Ctrl-A)
{27, 91, 'F'}: 5, // End (Ctrl-E)
}
// Key codes for 4-byte sequences (Page Up, Page Down, Home, End)
var pageNavLookup = map[[4]byte]int{
{27, 91, 49, 126}: 1, // Home (ESC [1~)
{27, 91, 52, 126}: 5, // End (ESC [4~)
{27, 91, 53, 126}: 251, // Page Up (custom code)
{27, 91, 54, 126}: 250, // Page Down (custom code)
}
// Key codes for 6-byte sequences (Ctrl-Insert)
var ctrlInsertLookup = map[[6]byte]int{
{27, 91, 50, 59, 53, 126}: 258, // Ctrl-Insert (ESC [2;5~)
}
// String representations for 3-byte sequences
var keyStringLookup = map[[3]byte]string{
{27, 91, 65}: "↑", // Up Arrow
{27, 91, 66}: "↓", // Down Arrow
{27, 91, 67}: "→", // Right Arrow
{27, 91, 68}: "←", // Left Arrow
{27, 91, 'H'}: "⇱", // Home
{27, 91, 'F'}: "⇲", // End
}
// String representations for 4-byte sequences
var pageStringLookup = map[[4]byte]string{
{27, 91, 49, 126}: "⇱", // Home
{27, 91, 52, 126}: "⇲", // End
{27, 91, 53, 126}: "⇞", // Page Up
{27, 91, 54, 126}: "⇟", // Page Down
}
// String representations for 6-byte sequences (Ctrl-Insert)
var ctrlInsertStringLookup = map[[6]byte]string{
{27, 91, 50, 59, 53, 126}: "⎘", // Ctrl-Insert (Copy)
}
type TTY struct {
t *term.Term
timeout time.Duration
}
// NewTTY opens /dev/tty in raw and cbreak mode as a term.Term
func NewTTY() (*TTY, error) {
t, err := term.Open("/dev/tty", term.RawMode, term.CBreakMode, term.ReadTimeout(defaultTimeout))
if err != nil {
return nil, err
}
return &TTY{t, defaultTimeout}, nil
}
// SetTimeout sets a timeout for reading a key
func (tty *TTY) SetTimeout(d time.Duration) {
tty.timeout = d
tty.t.SetReadTimeout(tty.timeout)
}
// Close will restore and close the raw terminal
func (tty *TTY) Close() {
tty.t.Restore()
tty.t.Close()
}
// asciiAndKeyCode processes input into an ASCII code or key code, handling multi-byte sequences like Ctrl-Insert
func asciiAndKeyCode(tty *TTY) (ascii, keyCode int, err error) {
bytes := make([]byte, 6) // Use 6 bytes to cover longer sequences like Ctrl-Insert
var numRead int
// Set the terminal into raw mode and non-blocking mode with a timeout
tty.RawMode()
tty.NoBlock()
tty.SetTimeout(tty.timeout)
// Read bytes from the terminal
numRead, err = tty.t.Read(bytes)
// Restore the terminal settings
tty.Restore()
tty.t.Flush()
if err != nil {
return
}
// Handle multi-byte sequences
switch {
case numRead == 1:
ascii = int(bytes[0])
case numRead == 3:
seq := [3]byte{bytes[0], bytes[1], bytes[2]}
if code, found := keyCodeLookup[seq]; found {
keyCode = code
return
}
// Not found, check if it's a printable character
r, _ := utf8.DecodeRune(bytes[:numRead])
if unicode.IsPrint(r) {
ascii = int(r)
}
case numRead == 4:
seq := [4]byte{bytes[0], bytes[1], bytes[2], bytes[3]}
if code, found := pageNavLookup[seq]; found {
keyCode = code
return
}
case numRead == 6:
seq := [6]byte{bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]}
if code, found := ctrlInsertLookup[seq]; found {
keyCode = code
return
}
default:
// Attempt to decode as UTF-8
r, _ := utf8.DecodeRune(bytes[:numRead])
if unicode.IsPrint(r) {
ascii = int(r)
}
}
return
}
// Key reads the keycode or ASCII code and avoids repeated keys
func (tty *TTY) Key() int {
ascii, keyCode, err := asciiAndKeyCode(tty)
if err != nil {
lastKey = 0
return 0
}
var key int
if keyCode != 0 {
key = keyCode
} else {
key = ascii
}
if key == lastKey {
lastKey = 0
return 0
}
lastKey = key
return key
}
// String reads a string, handling key sequences and printable characters
func (tty *TTY) String() string {
bytes := make([]byte, 6)
var numRead int
// Set the terminal into raw mode with a timeout
tty.RawMode()
tty.SetTimeout(0)
// Read bytes from the terminal
numRead, err := tty.t.Read(bytes)
// Restore the terminal settings
tty.Restore()
tty.t.Flush()
if err != nil || numRead == 0 {
return ""
}
switch {
case numRead == 1:
r := rune(bytes[0])
if unicode.IsPrint(r) {
return string(r)
}
return "c:" + strconv.Itoa(int(r))
case numRead == 3:
seq := [3]byte{bytes[0], bytes[1], bytes[2]}
if str, found := keyStringLookup[seq]; found {
return str
}
// Attempt to interpret as UTF-8 string
return string(bytes[:numRead])
case numRead == 4:
seq := [4]byte{bytes[0], bytes[1], bytes[2], bytes[3]}
if str, found := pageStringLookup[seq]; found {
return str
}
return string(bytes[:numRead])
case numRead == 6:
seq := [6]byte{bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]}
if str, found := ctrlInsertStringLookup[seq]; found {
return str
}
return string(bytes[:numRead])
default:
// Attempt to interpret as UTF-8 string
return string(bytes[:numRead])
}
}
// Rune reads a rune, handling special sequences for arrows, Home, End, etc.
func (tty *TTY) Rune() rune {
bytes := make([]byte, 6)
var numRead int
// Set the terminal into raw mode with a timeout
tty.RawMode()
tty.SetTimeout(0)
// Read bytes from the terminal
numRead, err := tty.t.Read(bytes)
// Restore the terminal settings
tty.Restore()
tty.t.Flush()
if err != nil || numRead == 0 {
return rune(0)
}
switch {
case numRead == 1:
return rune(bytes[0])
case numRead == 3:
seq := [3]byte{bytes[0], bytes[1], bytes[2]}
if str, found := keyStringLookup[seq]; found {
return []rune(str)[0]
}
// Attempt to interpret as UTF-8 rune
r, _ := utf8.DecodeRune(bytes[:numRead])
return r
case numRead == 4:
seq := [4]byte{bytes[0], bytes[1], bytes[2], bytes[3]}
if str, found := pageStringLookup[seq]; found {
return []rune(str)[0]
}
r, _ := utf8.DecodeRune(bytes[:numRead])
return r
case numRead == 6:
seq := [6]byte{bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5]}
if str, found := ctrlInsertStringLookup[seq]; found {
return []rune(str)[0]
}
r, _ := utf8.DecodeRune(bytes[:numRead])
return r
default:
// Attempt to interpret as UTF-8 rune
r, _ := utf8.DecodeRune(bytes[:numRead])
return r
}
}
// RawMode switches the terminal to raw mode
func (tty *TTY) RawMode() {
term.RawMode(tty.t)
}
// NoBlock sets the terminal to cbreak mode (non-blocking)
func (tty *TTY) NoBlock() {
tty.t.SetCbreak()
}
// Restore the terminal to its original state
func (tty *TTY) Restore() {
tty.t.Restore()
}
// Flush flushes the terminal output
func (tty *TTY) Flush() {
tty.t.Flush()
}
// WriteString writes a string to the terminal
func (tty *TTY) WriteString(s string) error {
if n, err := tty.t.Write([]byte(s)); err != nil || n == 0 {
return errors.New("no bytes written to the TTY")
}
return nil
}
// ReadString reads a string from the TTY
func (tty *TTY) ReadString() (string, error) {
b, err := io.ReadAll(tty.t)
if err != nil {
return "", err
}
return string(b), nil
}
// PrintRawBytes for debugging raw byte sequences
func (tty *TTY) PrintRawBytes() {
bytes := make([]byte, 6)
var numRead int
// Set the terminal into raw mode with a timeout
tty.RawMode()
tty.SetTimeout(0)
// Read bytes from the terminal
numRead, err := tty.t.Read(bytes)
// Restore the terminal settings
tty.Restore()
tty.t.Flush()
if err != nil {
fmt.Println("Error:", err)
return
}
fmt.Printf("Raw bytes: %v\n", bytes[:numRead])
}
// Term will return the underlying term.Term
func (tty *TTY) Term() *term.Term {
return tty.t
}
// asciiAndKeyCodeOnce reads a single key press and returns the ASCII code and key code
func asciiAndKeyCodeOnce() (ascii, keyCode int, err error) {
t, err := NewTTY()
if err != nil {
return 0, 0, err
}
a, kc, err := asciiAndKeyCode(t)
t.Close()
return a, kc, err
}
// ASCII returns the ASCII code of the key pressed
func (tty *TTY) ASCII() int {
ascii, _, err := asciiAndKeyCode(tty)
if err != nil {
return 0
}
return ascii
}
// ASCIIOnce returns the ASCII code of a single key press
func ASCIIOnce() int {
ascii, _, err := asciiAndKeyCodeOnce()
if err != nil {
return 0
}
return ascii
}
// KeyCode returns the key code of the key pressed
func (tty *TTY) KeyCode() int {
_, keyCode, err := asciiAndKeyCode(tty)
if err != nil {
return 0
}
return keyCode
}
// KeyCodeOnce returns the key code of a single key press
func KeyCodeOnce() int {
_, keyCode, err := asciiAndKeyCodeOnce()
if err != nil {
return 0
}
return keyCode
}
// WaitForKey waits for Return, Esc, Space, or 'q' to be pressed
func WaitForKey() {
// Get a new TTY and start reading keypresses in a loop
r, err := NewTTY()
if err != nil {
panic(err)
}
defer r.Close()
for {
switch r.Key() {
case 13, 27, 32, 113:
return
}
}
}