From 01a81100bbd30782c6fcd262fb80b4ccc7db3134 Mon Sep 17 00:00:00 2001
From: Lixen Wraith <lixen.wraith@gmail.com>
Date: Fri, 16 Oct 2026 23:48:40 -0400
Subject: [PATCH] v0.4.1 export control key

---
 controlkey_test.go | 26 ++++++++++++++++++++++++++
 input.go           | 27 +++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 controlkey_test.go

diff --git a/controlkey_test.go b/controlkey_test.go
new file mode 100644
index 0000000..8d295a2
--- /dev/null
+++ b/controlkey_test.go
@@ -0,0 +1,26 @@
+package terminal
+
+import "testing"
+
+func TestControlKey(t *testing.T) {
+	cases := map[rune]Key{
+		'a': KeyCtrlA, 'G': KeyCtrlG, 'z': KeyCtrlZ,
+		'h': KeyBackspace, 'i': KeyTab, 'j': KeyEnter, 'm': KeyEnter,
+		' ': KeyCtrlSpace, '@': KeyCtrlSpace, '2': KeyCtrlSpace,
+		'[': KeyEscape, '3': KeyEscape,
+		'\\': KeyCtrlBackslash, '4': KeyCtrlBackslash,
+		']': KeyCtrlBracketRight, '5': KeyCtrlBracketRight,
+		'^': KeyCtrlCaret, '6': KeyCtrlCaret,
+		'_': KeyCtrlUnderscore, '-': KeyCtrlUnderscore, '/': KeyCtrlUnderscore, '7': KeyCtrlUnderscore,
+	}
+	for r, want := range cases {
+		if got, ok := ControlKey(r); !ok || got != want {
+			t.Errorf("ControlKey(%q) = %v, %v; want %v, true", r, got, ok, want)
+		}
+	}
+	for _, r := range []rune{'1', '8', '.', '~', 'é', 0} {
+		if _, ok := ControlKey(r); ok {
+			t.Errorf("ControlKey(%q) ok, want none", r)
+		}
+	}
+}
diff --git a/input.go b/input.go
index f0df248..caa87e9 100644
--- a/input.go
+++ b/input.go
@@ -663,3 +663,30 @@ func decodeRune(data []byte) (rune, int) {
 
 	return r, size
 }
+
+// ControlKey is the key a terminal reads for Ctrl with a printable character: the
+// control byte that pair sends, parsed as input parsing reads it. Letters of
+// either case, space and '@', '[' '\' ']' '^' '_', '-' and '/' as '_', and the
+// digits 2 to 7 have one; ok is false for any other character.
+func ControlKey(r rune) (Key, bool) {
+	var b byte
+	switch {
+	case r >= 'a' && r <= 'z', r >= 'A' && r <= 'Z':
+		b = byte(r) & 0x1f
+	case r == ' ', r == '@', r == '2':
+		b = 0x00
+	case r == '[', r == '3':
+		b = 0x1b
+	case r == '\\', r == '4':
+		b = 0x1c
+	case r == ']', r == '5':
+		b = 0x1d
+	case r == '^', r == '6':
+		b = 0x1e
+	case r == '_', r == '-', r == '/', r == '7':
+		b = 0x1f
+	default:
+		return KeyNone, false
+	}
+	return (*inputReader)(nil).parseControl(b).Key, true
+}