From f892600c35265c3b2d0c79322107239c1ec9479b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ji=C5=99=C3=AD=20Setni=C4=8Dka?= <setnicka@seznam.cz>
Date: Mon, 20 Feb 2017 02:51:01 +0100
Subject: [PATCH] Ability to filter out input runes (#104)

Could be used to mask/disable some actions (like Ctrl-Z, or searching by
Ctrl-R and Ctrl-S)
---
 example/readline-demo/readline-demo.go | 12 +++++++++++-
 operation.go                           |  9 +++++++++
 readline.go                            |  4 ++++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/example/readline-demo/readline-demo.go b/example/readline-demo/readline-demo.go
index cb6fb1a..2b1daf7 100644
--- a/example/readline-demo/readline-demo.go
+++ b/example/readline-demo/readline-demo.go
@@ -61,6 +61,15 @@ var completer = readline.NewPrefixCompleter(
 	readline.PcItem("sleep"),
 )
 
+func filterInput(r rune) (rune, bool) {
+	switch r {
+	// block CtrlZ feature
+	case readline.CharCtrlZ:
+		return r, false
+	}
+	return r, true
+}
+
 func main() {
 	l, err := readline.NewEx(&readline.Config{
 		Prompt:          "\033[31m»\033[0m ",
@@ -69,7 +78,8 @@ func main() {
 		InterruptPrompt: "^C",
 		EOFPrompt:       "exit",
 
-		HistorySearchFold: true,
+		HistorySearchFold:   true,
+		FuncFilterInputRune: filterInput,
 	})
 	if err != nil {
 		panic(err)
diff --git a/operation.go b/operation.go
index 8377cce..14ade31 100644
--- a/operation.go
+++ b/operation.go
@@ -96,6 +96,15 @@ func (o *Operation) ioloop() {
 		keepInSearchMode := false
 		keepInCompleteMode := false
 		r := o.t.ReadRune()
+		if o.cfg.FuncFilterInputRune != nil {
+			var process bool
+			r, process = o.cfg.FuncFilterInputRune(r)
+			if !process {
+				o.buf.Refresh(nil) // to refresh the line
+				continue           // ignore this rune
+			}
+		}
+
 		if r == 0 { // io.EOF
 			if o.buf.Len() == 0 {
 				o.buf.Clean()
diff --git a/readline.go b/readline.go
index 1e232fb..3f02a83 100644
--- a/readline.go
+++ b/readline.go
@@ -63,6 +63,10 @@ type Config struct {
 	// it use in IM usually.
 	UniqueEditLine bool
 
+	// filter input runes (may be used to disable CtrlZ or for translating some keys to different actions)
+	// -> output = new (translated) rune and true/false if continue with processing this one
+	FuncFilterInputRune func(rune) (rune, bool)
+
 	// force use interactive even stdout is not a tty
 	FuncIsTerminal      func() bool
 	FuncMakeRaw         func() error