Add mnemonic mute controls

uiterm/key_toml.go

@@ -1,15 +1,31 @@
 package uiterm
 
+import (
+	"fmt"
+	"unicode"
+	"unicode/utf8"
+)
+
 // MarshalText implements the encoding.TextMarshaler interface for Key
 // This allows TOML to serialize Key values as strings
 func (i Key) MarshalText() ([]byte, error) {
+	if r := rune(i); r >= 0x21 && r <= unicode.MaxASCII && unicode.IsPrint(r) {
+		return []byte(string(r)), nil
+	}
 	return []byte(i.String()), nil
 }
 
 // UnmarshalText implements the encoding.TextUnmarshaler interface for Key
 // This allows TOML to deserialize strings back into Key values
 func (i *Key) UnmarshalText(data []byte) error {
+	if r, size := utf8.DecodeRune(data); r != utf8.RuneError && size == len(data) && unicode.IsPrint(r) {
+		*i = Key(unicode.ToLower(r))
+		return nil
+	}
 	var err error
 	*i, err = KeyString(string(data))
+	if err != nil {
+		return fmt.Errorf("invalid key %q: %w", data, err)
+	}
 	return err
 }

uiterm/key_toml_test.go

@@ -0,0 +1,35 @@
+package uiterm
+
+import "testing"
+
+func TestPrintableKeyTextRoundTrip(t *testing.T) {
+	encoded, err := KeyM.MarshalText()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(encoded) != "m" {
+		t.Fatalf("encoded key = %q, want m", encoded)
+	}
+
+	var decoded Key
+	if err := decoded.UnmarshalText([]byte("M")); err != nil {
+		t.Fatal(err)
+	}
+	if decoded != KeyM {
+		t.Fatalf("decoded key = %v, want %v", decoded, KeyM)
+	}
+}
+
+func TestNamedKeyTextStillRoundTrips(t *testing.T) {
+	encoded, err := KeyCtrlT.MarshalText()
+	if err != nil {
+		t.Fatal(err)
+	}
+	var decoded Key
+	if err := decoded.UnmarshalText(encoded); err != nil {
+		t.Fatal(err)
+	}
+	if decoded != KeyCtrlT {
+		t.Fatalf("decoded key = %v, want %v", decoded, KeyCtrlT)
+	}
+}

uiterm/printable_keys.go

@@ -0,0 +1,5 @@
+package uiterm
+
+// Printable keys normally arrive through a view's character handler rather
+// than the special-key handler.
+const KeyM Key = 'm'