From 6cbf970b0b5f8014bf6a06764900cc89a4622bb2 Mon Sep 17 00:00:00 2001
From: chzyer <0@0xdf.com>
Date: Sun, 4 Sep 2016 21:02:24 +0800
Subject: [PATCH] lazy init CancelableStdin() (#78)

---
 readline.go |  2 +-
 std.go      | 13 ++++++-------
 2 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/readline.go b/readline.go
index 14af1dd..1e67f51 100644
--- a/readline.go
+++ b/readline.go
@@ -87,7 +87,7 @@ func (c *Config) Init() error {
 	}
 	c.inited = true
 	if c.Stdin == nil {
-		c.Stdin = Stdin
+		c.Stdin = NewCancelableStdin(Stdin)
 	}
 	if c.Stdout == nil {
 		c.Stdout = Stdout
diff --git a/std.go b/std.go
index 28439f9..622e66e 100644
--- a/std.go
+++ b/std.go
@@ -7,7 +7,7 @@ import (
 )
 
 var (
-	Stdin  io.ReadCloser  = NewCancelableStdin()
+	Stdin  io.ReadCloser  = os.Stdin
 	Stdout io.WriteCloser = os.Stdout
 	Stderr io.WriteCloser = os.Stderr
 )
@@ -66,6 +66,7 @@ func Line(prompt string) (string, error) {
 }
 
 type CancelableStdin struct {
+	r           io.Reader
 	mutex       sync.Mutex
 	stop        chan struct{}
 	notify      chan struct{}
@@ -75,11 +76,13 @@ type CancelableStdin struct {
 	ioloopFired bool
 }
 
-func NewCancelableStdin() *CancelableStdin {
+func NewCancelableStdin(r io.Reader) *CancelableStdin {
 	c := &CancelableStdin{
+		r:      r,
 		notify: make(chan struct{}),
 		stop:   make(chan struct{}),
 	}
+	go c.ioloop()
 	return c
 }
 
@@ -88,7 +91,7 @@ loop:
 	for {
 		select {
 		case <-c.notify:
-			c.read, c.err = os.Stdin.Read(c.data)
+			c.read, c.err = c.r.Read(c.data)
 			c.notify <- struct{}{}
 		case <-c.stop:
 			break loop
@@ -99,10 +102,6 @@ loop:
 func (c *CancelableStdin) Read(b []byte) (n int, err error) {
 	c.mutex.Lock()
 	defer c.mutex.Unlock()
-	if !c.ioloopFired {
-		c.ioloopFired = true
-		go c.ioloop()
-	}
 
 	c.data = b
 	c.notify <- struct{}{}