bubbletea/key.go

687 lines
20 KiB
Go

package tea
import (
"context"
"fmt"
"io"
"regexp"
"unicode/utf8"
)
// KeyMsg contains information about a keypress. KeyMsgs are always sent to
// the program's update function. There are a couple general patterns you could
// use to check for keypresses:
//
// // Switch on the string representation of the key (shorter)
// switch msg := msg.(type) {
// case KeyMsg:
// switch msg.String() {
// case "enter":
// fmt.Println("you pressed enter!")
// case "a":
// fmt.Println("you pressed a!")
// }
// }
//
// // Switch on the key type (more foolproof)
// switch msg := msg.(type) {
// case KeyMsg:
// switch msg.Type {
// case KeyEnter:
// fmt.Println("you pressed enter!")
// case KeyRunes:
// switch string(msg.Runes) {
// case "a":
// fmt.Println("you pressed a!")
// }
// }
// }
//
// Note that Key.Runes will always contain at least one character, so you can
// always safely call Key.Runes[0]. In most cases Key.Runes will only contain
// one character, though certain input method editors (most notably Chinese
// IMEs) can input multiple runes at once.
type KeyMsg Key
// String returns a string representation for a key message. It's safe (and
// encouraged) for use in key comparison.
func (k KeyMsg) String() (str string) {
return Key(k).String()
}
// Key contains information about a keypress.
type Key struct {
Type KeyType
Runes []rune
Alt bool
}
// String returns a friendly string representation for a key. It's safe (and
// encouraged) for use in key comparison.
//
// k := Key{Type: KeyEnter}
// fmt.Println(k)
// // Output: enter
func (k Key) String() (str string) {
if k.Alt {
str += "alt+"
}
if k.Type == KeyRunes {
str += string(k.Runes)
return str
} else if s, ok := keyNames[k.Type]; ok {
str += s
return str
}
return ""
}
// KeyType indicates the key pressed, such as KeyEnter or KeyBreak or KeyCtrlC.
// All other keys will be type KeyRunes. To get the rune value, check the Rune
// method on a Key struct, or use the Key.String() method:
//
// k := Key{Type: KeyRunes, Runes: []rune{'a'}, Alt: true}
// if k.Type == KeyRunes {
//
// fmt.Println(k.Runes)
// // Output: a
//
// fmt.Println(k.String())
// // Output: alt+a
//
// }
type KeyType int
func (k KeyType) String() (str string) {
if s, ok := keyNames[k]; ok {
return s
}
return ""
}
// Control keys. We could do this with an iota, but the values are very
// specific, so we set the values explicitly to avoid any confusion.
//
// See also:
// https://en.wikipedia.org/wiki/C0_and_C1_control_codes
const (
keyNUL KeyType = 0 // null, \0
keySOH KeyType = 1 // start of heading
keySTX KeyType = 2 // start of text
keyETX KeyType = 3 // break, ctrl+c
keyEOT KeyType = 4 // end of transmission
keyENQ KeyType = 5 // enquiry
keyACK KeyType = 6 // acknowledge
keyBEL KeyType = 7 // bell, \a
keyBS KeyType = 8 // backspace
keyHT KeyType = 9 // horizontal tabulation, \t
keyLF KeyType = 10 // line feed, \n
keyVT KeyType = 11 // vertical tabulation \v
keyFF KeyType = 12 // form feed \f
keyCR KeyType = 13 // carriage return, \r
keySO KeyType = 14 // shift out
keySI KeyType = 15 // shift in
keyDLE KeyType = 16 // data link escape
keyDC1 KeyType = 17 // device control one
keyDC2 KeyType = 18 // device control two
keyDC3 KeyType = 19 // device control three
keyDC4 KeyType = 20 // device control four
keyNAK KeyType = 21 // negative acknowledge
keySYN KeyType = 22 // synchronous idle
keyETB KeyType = 23 // end of transmission block
keyCAN KeyType = 24 // cancel
keyEM KeyType = 25 // end of medium
keySUB KeyType = 26 // substitution
keyESC KeyType = 27 // escape, \e
keyFS KeyType = 28 // file separator
keyGS KeyType = 29 // group separator
keyRS KeyType = 30 // record separator
keyUS KeyType = 31 // unit separator
keyDEL KeyType = 127 // delete. on most systems this is mapped to backspace, I hear
)
// Control key aliases.
const (
KeyNull KeyType = keyNUL
KeyBreak KeyType = keyETX
KeyEnter KeyType = keyCR
KeyBackspace KeyType = keyDEL
KeyTab KeyType = keyHT
KeyEsc KeyType = keyESC
KeyEscape KeyType = keyESC
KeyCtrlAt KeyType = keyNUL // ctrl+@
KeyCtrlA KeyType = keySOH
KeyCtrlB KeyType = keySTX
KeyCtrlC KeyType = keyETX
KeyCtrlD KeyType = keyEOT
KeyCtrlE KeyType = keyENQ
KeyCtrlF KeyType = keyACK
KeyCtrlG KeyType = keyBEL
KeyCtrlH KeyType = keyBS
KeyCtrlI KeyType = keyHT
KeyCtrlJ KeyType = keyLF
KeyCtrlK KeyType = keyVT
KeyCtrlL KeyType = keyFF
KeyCtrlM KeyType = keyCR
KeyCtrlN KeyType = keySO
KeyCtrlO KeyType = keySI
KeyCtrlP KeyType = keyDLE
KeyCtrlQ KeyType = keyDC1
KeyCtrlR KeyType = keyDC2
KeyCtrlS KeyType = keyDC3
KeyCtrlT KeyType = keyDC4
KeyCtrlU KeyType = keyNAK
KeyCtrlV KeyType = keySYN
KeyCtrlW KeyType = keyETB
KeyCtrlX KeyType = keyCAN
KeyCtrlY KeyType = keyEM
KeyCtrlZ KeyType = keySUB
KeyCtrlOpenBracket KeyType = keyESC // ctrl+[
KeyCtrlBackslash KeyType = keyFS // ctrl+\
KeyCtrlCloseBracket KeyType = keyGS // ctrl+]
KeyCtrlCaret KeyType = keyRS // ctrl+^
KeyCtrlUnderscore KeyType = keyUS // ctrl+_
KeyCtrlQuestionMark KeyType = keyDEL // ctrl+?
)
// Other keys.
const (
KeyRunes KeyType = -(iota + 1)
KeyUp
KeyDown
KeyRight
KeyLeft
KeyShiftTab
KeyHome
KeyEnd
KeyPgUp
KeyPgDown
KeyCtrlPgUp
KeyCtrlPgDown
KeyDelete
KeyInsert
KeySpace
KeyCtrlUp
KeyCtrlDown
KeyCtrlRight
KeyCtrlLeft
KeyCtrlHome
KeyCtrlEnd
KeyShiftUp
KeyShiftDown
KeyShiftRight
KeyShiftLeft
KeyShiftHome
KeyShiftEnd
KeyCtrlShiftUp
KeyCtrlShiftDown
KeyCtrlShiftLeft
KeyCtrlShiftRight
KeyCtrlShiftHome
KeyCtrlShiftEnd
KeyF1
KeyF2
KeyF3
KeyF4
KeyF5
KeyF6
KeyF7
KeyF8
KeyF9
KeyF10
KeyF11
KeyF12
KeyF13
KeyF14
KeyF15
KeyF16
KeyF17
KeyF18
KeyF19
KeyF20
)
// Mappings for control keys and other special keys to friendly consts.
var keyNames = map[KeyType]string{
// Control keys.
keyNUL: "ctrl+@", // also ctrl+` (that's ctrl+backtick)
keySOH: "ctrl+a",
keySTX: "ctrl+b",
keyETX: "ctrl+c",
keyEOT: "ctrl+d",
keyENQ: "ctrl+e",
keyACK: "ctrl+f",
keyBEL: "ctrl+g",
keyBS: "ctrl+h",
keyHT: "tab", // also ctrl+i
keyLF: "ctrl+j",
keyVT: "ctrl+k",
keyFF: "ctrl+l",
keyCR: "enter",
keySO: "ctrl+n",
keySI: "ctrl+o",
keyDLE: "ctrl+p",
keyDC1: "ctrl+q",
keyDC2: "ctrl+r",
keyDC3: "ctrl+s",
keyDC4: "ctrl+t",
keyNAK: "ctrl+u",
keySYN: "ctrl+v",
keyETB: "ctrl+w",
keyCAN: "ctrl+x",
keyEM: "ctrl+y",
keySUB: "ctrl+z",
keyESC: "esc",
keyFS: "ctrl+\\",
keyGS: "ctrl+]",
keyRS: "ctrl+^",
keyUS: "ctrl+_",
keyDEL: "backspace",
// Other keys.
KeyRunes: "runes",
KeyUp: "up",
KeyDown: "down",
KeyRight: "right",
KeySpace: " ", // for backwards compatibility
KeyLeft: "left",
KeyShiftTab: "shift+tab",
KeyHome: "home",
KeyEnd: "end",
KeyCtrlHome: "ctrl+home",
KeyCtrlEnd: "ctrl+end",
KeyShiftHome: "shift+home",
KeyShiftEnd: "shift+end",
KeyCtrlShiftHome: "ctrl+shift+home",
KeyCtrlShiftEnd: "ctrl+shift+end",
KeyPgUp: "pgup",
KeyPgDown: "pgdown",
KeyCtrlPgUp: "ctrl+pgup",
KeyCtrlPgDown: "ctrl+pgdown",
KeyDelete: "delete",
KeyInsert: "insert",
KeyCtrlUp: "ctrl+up",
KeyCtrlDown: "ctrl+down",
KeyCtrlRight: "ctrl+right",
KeyCtrlLeft: "ctrl+left",
KeyShiftUp: "shift+up",
KeyShiftDown: "shift+down",
KeyShiftRight: "shift+right",
KeyShiftLeft: "shift+left",
KeyCtrlShiftUp: "ctrl+shift+up",
KeyCtrlShiftDown: "ctrl+shift+down",
KeyCtrlShiftLeft: "ctrl+shift+left",
KeyCtrlShiftRight: "ctrl+shift+right",
KeyF1: "f1",
KeyF2: "f2",
KeyF3: "f3",
KeyF4: "f4",
KeyF5: "f5",
KeyF6: "f6",
KeyF7: "f7",
KeyF8: "f8",
KeyF9: "f9",
KeyF10: "f10",
KeyF11: "f11",
KeyF12: "f12",
KeyF13: "f13",
KeyF14: "f14",
KeyF15: "f15",
KeyF16: "f16",
KeyF17: "f17",
KeyF18: "f18",
KeyF19: "f19",
KeyF20: "f20",
}
// Sequence mappings.
var sequences = map[string]Key{
// Arrow keys
"\x1b[A": {Type: KeyUp},
"\x1b[B": {Type: KeyDown},
"\x1b[C": {Type: KeyRight},
"\x1b[D": {Type: KeyLeft},
"\x1b[1;2A": {Type: KeyShiftUp},
"\x1b[1;2B": {Type: KeyShiftDown},
"\x1b[1;2C": {Type: KeyShiftRight},
"\x1b[1;2D": {Type: KeyShiftLeft},
"\x1b[OA": {Type: KeyShiftUp}, // DECCKM
"\x1b[OB": {Type: KeyShiftDown}, // DECCKM
"\x1b[OC": {Type: KeyShiftRight}, // DECCKM
"\x1b[OD": {Type: KeyShiftLeft}, // DECCKM
"\x1b[a": {Type: KeyShiftUp}, // urxvt
"\x1b[b": {Type: KeyShiftDown}, // urxvt
"\x1b[c": {Type: KeyShiftRight}, // urxvt
"\x1b[d": {Type: KeyShiftLeft}, // urxvt
"\x1b[1;3A": {Type: KeyUp, Alt: true},
"\x1b[1;3B": {Type: KeyDown, Alt: true},
"\x1b[1;3C": {Type: KeyRight, Alt: true},
"\x1b[1;3D": {Type: KeyLeft, Alt: true},
"\x1b[1;4A": {Type: KeyShiftUp, Alt: true},
"\x1b[1;4B": {Type: KeyShiftDown, Alt: true},
"\x1b[1;4C": {Type: KeyShiftRight, Alt: true},
"\x1b[1;4D": {Type: KeyShiftLeft, Alt: true},
"\x1b[1;5A": {Type: KeyCtrlUp},
"\x1b[1;5B": {Type: KeyCtrlDown},
"\x1b[1;5C": {Type: KeyCtrlRight},
"\x1b[1;5D": {Type: KeyCtrlLeft},
"\x1b[Oa": {Type: KeyCtrlUp, Alt: true}, // urxvt
"\x1b[Ob": {Type: KeyCtrlDown, Alt: true}, // urxvt
"\x1b[Oc": {Type: KeyCtrlRight, Alt: true}, // urxvt
"\x1b[Od": {Type: KeyCtrlLeft, Alt: true}, // urxvt
"\x1b[1;6A": {Type: KeyCtrlShiftUp},
"\x1b[1;6B": {Type: KeyCtrlShiftDown},
"\x1b[1;6C": {Type: KeyCtrlShiftRight},
"\x1b[1;6D": {Type: KeyCtrlShiftLeft},
"\x1b[1;7A": {Type: KeyCtrlUp, Alt: true},
"\x1b[1;7B": {Type: KeyCtrlDown, Alt: true},
"\x1b[1;7C": {Type: KeyCtrlRight, Alt: true},
"\x1b[1;7D": {Type: KeyCtrlLeft, Alt: true},
"\x1b[1;8A": {Type: KeyCtrlShiftUp, Alt: true},
"\x1b[1;8B": {Type: KeyCtrlShiftDown, Alt: true},
"\x1b[1;8C": {Type: KeyCtrlShiftRight, Alt: true},
"\x1b[1;8D": {Type: KeyCtrlShiftLeft, Alt: true},
// Miscellaneous keys
"\x1b[Z": {Type: KeyShiftTab},
"\x1b[2~": {Type: KeyInsert},
"\x1b[3;2~": {Type: KeyInsert, Alt: true},
"\x1b[3~": {Type: KeyDelete},
"\x1b[3;3~": {Type: KeyDelete, Alt: true},
"\x1b[5~": {Type: KeyPgUp},
"\x1b[5;3~": {Type: KeyPgUp, Alt: true},
"\x1b[5;5~": {Type: KeyCtrlPgUp},
"\x1b[5^": {Type: KeyCtrlPgUp}, // urxvt
"\x1b[5;7~": {Type: KeyCtrlPgUp, Alt: true},
"\x1b[6~": {Type: KeyPgDown},
"\x1b[6;3~": {Type: KeyPgDown, Alt: true},
"\x1b[6;5~": {Type: KeyCtrlPgDown},
"\x1b[6^": {Type: KeyCtrlPgDown}, // urxvt
"\x1b[6;7~": {Type: KeyCtrlPgDown, Alt: true},
"\x1b[1~": {Type: KeyHome},
"\x1b[H": {Type: KeyHome}, // xterm, lxterm
"\x1b[1;3H": {Type: KeyHome, Alt: true}, // xterm, lxterm
"\x1b[1;5H": {Type: KeyCtrlHome}, // xterm, lxterm
"\x1b[1;7H": {Type: KeyCtrlHome, Alt: true}, // xterm, lxterm
"\x1b[1;2H": {Type: KeyShiftHome}, // xterm, lxterm
"\x1b[1;4H": {Type: KeyShiftHome, Alt: true}, // xterm, lxterm
"\x1b[1;6H": {Type: KeyCtrlShiftHome}, // xterm, lxterm
"\x1b[1;8H": {Type: KeyCtrlShiftHome, Alt: true}, // xterm, lxterm
"\x1b[4~": {Type: KeyEnd},
"\x1b[F": {Type: KeyEnd}, // xterm, lxterm
"\x1b[1;3F": {Type: KeyEnd, Alt: true}, // xterm, lxterm
"\x1b[1;5F": {Type: KeyCtrlEnd}, // xterm, lxterm
"\x1b[1;7F": {Type: KeyCtrlEnd, Alt: true}, // xterm, lxterm
"\x1b[1;2F": {Type: KeyShiftEnd}, // xterm, lxterm
"\x1b[1;4F": {Type: KeyShiftEnd, Alt: true}, // xterm, lxterm
"\x1b[1;6F": {Type: KeyCtrlShiftEnd}, // xterm, lxterm
"\x1b[1;8F": {Type: KeyCtrlShiftEnd, Alt: true}, // xterm, lxterm
"\x1b[7~": {Type: KeyHome}, // urxvt
"\x1b[7^": {Type: KeyCtrlHome}, // urxvt
"\x1b[7$": {Type: KeyShiftHome}, // urxvt
"\x1b[7@": {Type: KeyCtrlShiftHome}, // urxvt
"\x1b[8~": {Type: KeyEnd}, // urxvt
"\x1b[8^": {Type: KeyCtrlEnd}, // urxvt
"\x1b[8$": {Type: KeyShiftEnd}, // urxvt
"\x1b[8@": {Type: KeyCtrlShiftEnd}, // urxvt
// Function keys, Linux console
"\x1b[[A": {Type: KeyF1}, // linux console
"\x1b[[B": {Type: KeyF2}, // linux console
"\x1b[[C": {Type: KeyF3}, // linux console
"\x1b[[D": {Type: KeyF4}, // linux console
"\x1b[[E": {Type: KeyF5}, // linux console
// Function keys, X11
"\x1bOP": {Type: KeyF1}, // vt100, xterm
"\x1bOQ": {Type: KeyF2}, // vt100, xterm
"\x1bOR": {Type: KeyF3}, // vt100, xterm
"\x1bOS": {Type: KeyF4}, // vt100, xterm
"\x1b[1;3P": {Type: KeyF1, Alt: true}, // vt100, xterm
"\x1b[1;3Q": {Type: KeyF2, Alt: true}, // vt100, xterm
"\x1b[1;3R": {Type: KeyF3, Alt: true}, // vt100, xterm
"\x1b[1;3S": {Type: KeyF4, Alt: true}, // vt100, xterm
"\x1b[11~": {Type: KeyF1}, // urxvt
"\x1b[12~": {Type: KeyF2}, // urxvt
"\x1b[13~": {Type: KeyF3}, // urxvt
"\x1b[14~": {Type: KeyF4}, // urxvt
"\x1b[15~": {Type: KeyF5}, // vt100, xterm, also urxvt
"\x1b[15;3~": {Type: KeyF5, Alt: true}, // vt100, xterm, also urxvt
"\x1b[17~": {Type: KeyF6}, // vt100, xterm, also urxvt
"\x1b[18~": {Type: KeyF7}, // vt100, xterm, also urxvt
"\x1b[19~": {Type: KeyF8}, // vt100, xterm, also urxvt
"\x1b[20~": {Type: KeyF9}, // vt100, xterm, also urxvt
"\x1b[21~": {Type: KeyF10}, // vt100, xterm, also urxvt
"\x1b[17;3~": {Type: KeyF6, Alt: true}, // vt100, xterm
"\x1b[18;3~": {Type: KeyF7, Alt: true}, // vt100, xterm
"\x1b[19;3~": {Type: KeyF8, Alt: true}, // vt100, xterm
"\x1b[20;3~": {Type: KeyF9, Alt: true}, // vt100, xterm
"\x1b[21;3~": {Type: KeyF10, Alt: true}, // vt100, xterm
"\x1b[23~": {Type: KeyF11}, // vt100, xterm, also urxvt
"\x1b[24~": {Type: KeyF12}, // vt100, xterm, also urxvt
"\x1b[23;3~": {Type: KeyF11, Alt: true}, // vt100, xterm
"\x1b[24;3~": {Type: KeyF12, Alt: true}, // vt100, xterm
"\x1b[1;2P": {Type: KeyF13},
"\x1b[1;2Q": {Type: KeyF14},
"\x1b[25~": {Type: KeyF13}, // vt100, xterm, also urxvt
"\x1b[26~": {Type: KeyF14}, // vt100, xterm, also urxvt
"\x1b[25;3~": {Type: KeyF13, Alt: true}, // vt100, xterm
"\x1b[26;3~": {Type: KeyF14, Alt: true}, // vt100, xterm
"\x1b[1;2R": {Type: KeyF15},
"\x1b[1;2S": {Type: KeyF16},
"\x1b[28~": {Type: KeyF15}, // vt100, xterm, also urxvt
"\x1b[29~": {Type: KeyF16}, // vt100, xterm, also urxvt
"\x1b[28;3~": {Type: KeyF15, Alt: true}, // vt100, xterm
"\x1b[29;3~": {Type: KeyF16, Alt: true}, // vt100, xterm
"\x1b[15;2~": {Type: KeyF17},
"\x1b[17;2~": {Type: KeyF18},
"\x1b[18;2~": {Type: KeyF19},
"\x1b[19;2~": {Type: KeyF20},
"\x1b[31~": {Type: KeyF17},
"\x1b[32~": {Type: KeyF18},
"\x1b[33~": {Type: KeyF19},
"\x1b[34~": {Type: KeyF20},
// Powershell sequences.
"\x1bOA": {Type: KeyUp, Alt: false},
"\x1bOB": {Type: KeyDown, Alt: false},
"\x1bOC": {Type: KeyRight, Alt: false},
"\x1bOD": {Type: KeyLeft, Alt: false},
}
// unknownInputByteMsg is reported by the input reader when an invalid
// utf-8 byte is detected on the input. Currently, it is not handled
// further by bubbletea. However, having this event makes it possible
// to troubleshoot invalid inputs.
type unknownInputByteMsg byte
func (u unknownInputByteMsg) String() string {
return fmt.Sprintf("?%#02x?", int(u))
}
// unknownCSISequenceMsg is reported by the input reader when an
// unrecognized CSI sequence is detected on the input. Currently, it
// is not handled further by bubbletea. However, having this event
// makes it possible to troubleshoot invalid inputs.
type unknownCSISequenceMsg []byte
func (u unknownCSISequenceMsg) String() string {
return fmt.Sprintf("?CSI%+v?", []byte(u)[2:])
}
var spaceRunes = []rune{' '}
// readAnsiInputs reads keypress and mouse inputs from a TTY and produces messages
// containing information about the key or mouse events accordingly.
func readAnsiInputs(ctx context.Context, msgs chan<- Msg, input io.Reader) error {
var buf [256]byte
var leftOverFromPrevIteration []byte
loop:
for {
// Read and block.
numBytes, err := input.Read(buf[:])
if err != nil {
return fmt.Errorf("error reading input: %w", err)
}
b := buf[:numBytes]
if leftOverFromPrevIteration != nil {
b = append(leftOverFromPrevIteration, b...)
}
// If we had a short read (numBytes < len(buf)), we're sure that
// the end of this read is an event boundary, so there is no doubt
// if we are encountering the end of the buffer while parsing a message.
// However, if we've succeeded in filling up the buffer, there may
// be more data in the OS buffer ready to be read in, to complete
// the last message in the input. In that case, we will retry with
// the left over data in the next iteration.
canHaveMoreData := numBytes == len(buf)
var i, w int
for i, w = 0, 07; i < len(b); i += w {
var msg Msg
w, msg = detectOneMsg(b[i:], canHaveMoreData)
if w == 0 {
// Expecting more bytes beyond the current buffer. Try waiting
// for more input.
leftOverFromPrevIteration = make([]byte, 0, len(b[i:])+len(buf))
leftOverFromPrevIteration = append(leftOverFromPrevIteration, b[i:]...)
continue loop
}
select {
case msgs <- msg:
case <-ctx.Done():
err := ctx.Err()
if err != nil {
err = fmt.Errorf("found context error while reading input: %w", err)
}
return err
}
}
leftOverFromPrevIteration = nil
}
}
var (
unknownCSIRe = regexp.MustCompile(`^\x1b\[[\x30-\x3f]*[\x20-\x2f]*[\x40-\x7e]`)
mouseSGRRegex = regexp.MustCompile(`(\d+);(\d+);(\d+)([Mm])`)
)
func detectOneMsg(b []byte, canHaveMoreData bool) (w int, msg Msg) {
// Detect mouse events.
// X10 mouse events have a length of 6 bytes
const mouseEventX10Len = 6
if len(b) >= mouseEventX10Len && b[0] == '\x1b' && b[1] == '[' {
switch b[2] {
case 'M':
return mouseEventX10Len, MouseMsg(parseX10MouseEvent(b))
case '<':
if matchIndices := mouseSGRRegex.FindSubmatchIndex(b[3:]); matchIndices != nil {
// SGR mouse events length is the length of the match plus the length of the escape sequence
mouseEventSGRLen := matchIndices[1] + 3
return mouseEventSGRLen, MouseMsg(parseSGRMouseEvent(b))
}
}
}
// Detect escape sequence and control characters other than NUL,
// possibly with an escape character in front to mark the Alt
// modifier.
var foundSeq bool
foundSeq, w, msg = detectSequence(b)
if foundSeq {
return
}
// No non-NUL control character or escape sequence.
// If we are seeing at least an escape character, remember it for later below.
alt := false
i := 0
if b[0] == '\x1b' {
alt = true
i++
}
// Are we seeing a standalone NUL? This is not handled by detectSequence().
if i < len(b) && b[i] == 0 {
return i + 1, KeyMsg{Type: keyNUL, Alt: alt}
}
// Find the longest sequence of runes that are not control
// characters from this point.
var runes []rune
for rw := 0; i < len(b); i += rw {
var r rune
r, rw = utf8.DecodeRune(b[i:])
if r == utf8.RuneError || r <= rune(keyUS) || r == rune(keyDEL) || r == ' ' {
// Rune errors are handled below; control characters and spaces will
// be handled by detectSequence in the next call to detectOneMsg.
break
}
runes = append(runes, r)
if alt {
// We only support a single rune after an escape alt modifier.
i += rw
break
}
}
if i >= len(b) && canHaveMoreData {
// We have encountered the end of the input buffer. Alas, we can't
// be sure whether the data in the remainder of the buffer is
// complete (maybe there was a short read). Instead of sending anything
// dumb to the message channel, do a short read. The outer loop will
// handle this case by extending the buffer as necessary.
return 0, nil
}
// If we found at least one rune, we report the bunch of them as
// a single KeyRunes or KeySpace event.
if len(runes) > 0 {
k := Key{Type: KeyRunes, Runes: runes, Alt: alt}
if len(runes) == 1 && runes[0] == ' ' {
k.Type = KeySpace
}
return i, KeyMsg(k)
}
// We didn't find an escape sequence, nor a valid rune. Was this a
// lone escape character at the end of the input?
if alt && len(b) == 1 {
return 1, KeyMsg(Key{Type: KeyEscape})
}
// The character at the current position is neither an escape
// sequence, a valid rune start or a sole escape character. Report
// it as an invalid byte.
return 1, unknownInputByteMsg(b[0])
}