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// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd os400 solaris
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package readline
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import (
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	"io"
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	"os"
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	"os/signal"
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	"sync"
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	"syscall"
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)
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type winsize struct {
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	Row    uint16
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	Col    uint16
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	Xpixel uint16
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	Ypixel uint16
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}
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// SuspendMe use to send suspend signal to myself, when we in the raw mode.
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// For OSX it need to send to parent's pid
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// For Linux it need to send to myself
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func SuspendMe() {
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	p, _ := os.FindProcess(os.Getppid())
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	p.Signal(syscall.SIGTSTP)
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	p, _ = os.FindProcess(os.Getpid())
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	p.Signal(syscall.SIGTSTP)
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}
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// get width of the terminal
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func getWidth(stdoutFd int) int {
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	cols, _, err := GetSize(stdoutFd)
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	if err != nil {
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		return -1
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	}
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	return cols
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}
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func GetScreenWidth() int {
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	w := getWidth(syscall.Stdout)
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	if w < 0 {
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		w = getWidth(syscall.Stderr)
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	}
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	return w
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}
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// ClearScreen clears the console screen
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func ClearScreen(w io.Writer) (int, error) {
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	return w.Write([]byte("\033[H"))
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}
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func DefaultIsTerminal() bool {
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	return IsTerminal(syscall.Stdin) && (IsTerminal(syscall.Stdout) || IsTerminal(syscall.Stderr))
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}
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func GetStdin() int {
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	return syscall.Stdin
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}
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// -----------------------------------------------------------------------------
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var (
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	widthChange         sync.Once
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	widthChangeCallback func()
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)
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func DefaultOnWidthChanged(f func()) {
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	widthChangeCallback = f
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	widthChange.Do(func() {
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		ch := make(chan os.Signal, 1)
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		signal.Notify(ch, syscall.SIGWINCH)
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		go func() {
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			for {
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				_, ok := <-ch
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				if !ok {
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					break
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				}
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				widthChangeCallback()
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			}
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		}()
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	})
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}
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