Gets many keys working on the keyboard

.gitignore

@@ -0,0 +1 @@
+lines

main.go

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+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+
+	"tildegit.org/sloum/lines/termios"
+)
+
+const (
+	UpArrow rune = iota - 20
+	DownArrow
+	LeftArrow
+	RightArrow
+	Delete
+	Home
+	End
+	PrintScreen
+	PageUp
+	PageDown
+	Escape rune = 27
+	NewLine rune = 10
+	CarriageReturn rune = 13
+	BackSpace rune = 127
+)
+
+func readKey() (rune, error) {
+	reader := bufio.NewReader(os.Stdin)
+	char, _, err := reader.ReadRune()
+	if err != nil {
+		return 0, err
+	}
+	avail := reader.Buffered()
+	if char == Escape && avail > 0 {
+		var b strings.Builder
+		b.WriteRune(27)
+		for ; avail > 0; avail-- {
+			c, _, e := reader.ReadRune()
+			if e != nil {
+				break
+			}
+			b.WriteRune(c)
+		}
+		escSeq := b.String()
+		switch true {
+		case escSeq == "\033[A":
+			char = UpArrow
+		case escSeq == "\033[B":
+			char = DownArrow
+		case escSeq == "\033[C":
+			char = RightArrow
+		case escSeq == "\033[D":
+			char = LeftArrow
+		case escSeq == "\033[5~":
+			char = PageUp
+		case escSeq == "\033[6~":
+			char = PageDown
+		case IsHomeKey(escSeq):
+			char = Home
+		case IsEndKey(escSeq):
+			char = End
+		case escSeq == "\033[3~" || escSeq == "\033[P":
+			char = Delete
+		default:
+			fmt.Printf("Odd sequence: %s\n", escSeq[1:])
+		}
+	}
+	return char, nil
+}
+
+func IsHomeKey(seq string) bool {
+	switch seq {
+	case "\033[1~", "\033[7~", "\033[H", "\033OH":
+		return true
+	default:
+		return false
+	}
+}
+
+func IsEndKey(seq string) bool {
+	switch seq {
+	case "\033[4~", "\033[8~", "\033[F", "\033OF":
+		return true
+	default:
+		return false
+	}
+}
+
+func PrintKey(k rune) {
+	switch true {
+	case k == UpArrow:
+		fmt.Println("UpArrow")
+	case k == DownArrow:
+		fmt.Println("DownArrow")
+	case k == LeftArrow:
+		fmt.Println("LeftArrow")
+	case k == RightArrow:
+		fmt.Println("RightArrow")
+	case k == Escape:
+		fmt.Println("Escape")
+	case k == NewLine:
+		fmt.Println("NewLine")
+	case k == CarriageReturn:
+		fmt.Println("CarriageReturn")
+	case k == Delete:
+		fmt.Println("Delete")
+	case k == Home:
+		fmt.Println("Home")
+	case k == End:
+		fmt.Println("End")
+	case k == BackSpace:
+		fmt.Println("BackSpace")
+	default:
+		fmt.Printf("%c (%d)\n", k, k)
+	}
+
+}
+
+func main() {
+	termios.SetCharMode()
+
+	for {
+		k, e := readKey()
+		if e != nil {
+			fmt.Println(e.Error())
+			continue
+		}
+		PrintKey(k)
+		if k == NewLine || k == CarriageReturn {
+			break
+		}
+	}
+	termios.Restore()
+}

termios/consts_linux.go

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+// +build linux
+
+package termios
+
+import "syscall"
+
+const (
+	getTermiosIoctl = syscall.TCGETS
+	setTermiosIoctl = syscall.TCSETS
+)

termios/consts_nonlinux.go

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+// +build !linux
+
+package termios
+
+import "syscall"
+
+const (
+	getTermiosIoctl = syscall.TIOCGETA
+	setTermiosIoctl = syscall.TIOCSETAF
+)

termios/termios.go

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+package termios
+
+import (
+	"os"
+	"runtime"
+	"syscall"
+	"unsafe"
+)
+
+type winsize struct {
+	Row    uint16
+	Col    uint16
+	Xpixel uint16
+	Ypixel uint16
+}
+
+var fd = os.Stdin.Fd()
+var initial = getTermios()
+
+func ioctl(fd, request, argp uintptr) error {
+	if _, _, e := syscall.Syscall(syscall.SYS_IOCTL, fd, request, argp); e != 0 {
+		return e
+	}
+	return nil
+}
+
+func GetWindowSize() (int, int) {
+	var value winsize
+	ioctl(fd, syscall.TIOCGWINSZ, uintptr(unsafe.Pointer(&value)))
+	return int(value.Col), int(value.Row)
+}
+
+func getTermios() syscall.Termios {
+	var value syscall.Termios
+	err := ioctl(fd, getTermiosIoctl, uintptr(unsafe.Pointer(&value)))
+	if err != nil {
+		panic(err)
+	}
+	return value
+}
+
+func setTermios(termios syscall.Termios) {
+	err := ioctl(fd, setTermiosIoctl, uintptr(unsafe.Pointer(&termios)))
+	if err != nil {
+		panic(err)
+	}
+	runtime.KeepAlive(termios)
+}
+
+func SetCharMode() {
+	t := getTermios()
+	t.Lflag = t.Lflag ^ syscall.ICANON
+	t.Lflag = t.Lflag ^ syscall.ECHO
+	setTermios(t)
+}
+
+func SetLineMode() {
+	var t = getTermios()
+	t.Lflag = t.Lflag | (syscall.ICANON | syscall.ECHO)
+	setTermios(t)
+}
+
+func SetRawMode() {
+	t := getTermios()
+	t.Lflag = t.Lflag ^ syscall.ICANON
+	t.Lflag = t.Lflag ^ syscall.ECHO
+	t.Oflag = t.Oflag ^ syscall.OPOST
+	t.Iflag = t.Iflag ^ syscall.ICRNL
+	t.Iflag = t.Iflag ^ syscall.IXON
+	t.Cc[syscall.VMIN] = 0
+	t.Cc[syscall.VTIME] = 1
+	setTermios(t)
+}
+
+func Restore() {
+	setTermios(initial)
+}