New class Watcher

watcher.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"io"
+	"os"
+	"strings"
+
+	"github.com/aymanbagabas/go-pty"
+)
+
+type Watcher struct {
+	ch       <-chan string
+	lastline string
+}
+
+func NewWatcher(ptmx pty.Pty) *Watcher {
+	pipeline := make(chan string, 1024)
+	go io.Copy(ptmx, os.Stdin)
+	go func() {
+		for {
+			var buffer [1024]byte
+			n, err := ptmx.Read(buffer[:])
+			if err != nil {
+				close(pipeline)
+				return
+			}
+			// If the code below spends a lot of time,
+			// It hangs up to io.Copy(ptmx, os.Stdin)
+			// The reason is unknown.
+			os.Stdout.Write(buffer[:n])
+			pipeline <- string(buffer[:n])
+		}
+	}()
+
+	return &Watcher{ch: pipeline}
+}
+
+func (W *Watcher) updateLastLine() {
+	newLinePos := strings.LastIndexByte(W.lastline, '\n')
+	if newLinePos >= 0 {
+		W.lastline = W.lastline[newLinePos+1:]
+	} else {
+		W.lastline = ""
+	}
+}
+
+func (W *Watcher) Expect(words ...string) int {
+	for frag := range W.ch {
+		W.lastline += frag
+		for i, word := range words {
+			if strings.Contains(W.lastline, word) {
+				W.updateLastLine()
+				return i
+			}
+		}
+		W.updateLastLine()
+	}
+	return -1
+}