Fix handling of arrow keys with alt and/or shift modifier

Fix #2254

- Properly handle extra chars in the buffer. Patch suggested by @mckelly2833.
- Support alt-arrow sequences in \e[1;3A format
- Support shift-alt-arrow sequences in \e[1;10A format

man/man1/fzf.1

@@ -21,7 +21,7 @@ LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 THE SOFTWARE.
 ..
-.TH fzf 1 "Nov 2020" "fzf 0.24.3" "fzf - a command-line fuzzy finder"
+.TH fzf 1 "Nov 2020" "fzf 0.24.4" "fzf - a command-line fuzzy finder"
 
 .SH NAME
 fzf - a command-line fuzzy finder
@@ -712,6 +712,14 @@ e.g.
 .br
 \fIshift-right\fR
 .br
+\fIalt-shift-up\fR
+.br
+\fIalt-shift-down\fR
+.br
+\fIalt-shift-left\fR
+.br
+\fIalt-shift-right\fR
+.br
 \fIleft-click\fR
 .br
 \fIright-click\fR

src/options.go

@@ -524,6 +524,14 @@ func parseKeyChords(str string, message string) map[int]string {
 			chord = tui.PgUp
 		case "pgdn", "page-down":
 			chord = tui.PgDn
+		case "alt-shift-up", "shift-alt-up":
+			chord = tui.AltSUp
+		case "alt-shift-down", "shift-alt-down":
+			chord = tui.AltSDown
+		case "alt-shift-left", "shift-alt-left":
+			chord = tui.AltSLeft
+		case "alt-shift-right", "shift-alt-right":
+			chord = tui.AltSRight
 		case "shift-up":
 			chord = tui.SUp
 		case "shift-down":

src/tui/light.go

@@ -463,20 +463,54 @@ func (r *LightRenderer) escSequence(sz *int) Event {
 					}
 					return Event{Invalid, 0, nil}
 				case ';':
-					if len(r.buffer) != 6 {
+					if len(r.buffer) < 6 {
 						return Event{Invalid, 0, nil}
 					}
 					*sz = 6
 					switch r.buffer[4] {
-					case '2', '5':
+					case '1', '2', '3', '5':
-						switch r.buffer[5] {
+						alt := r.buffer[4] == '3'
+						altShift := r.buffer[4] == '1' && r.buffer[5] == '0'
+						char := r.buffer[5]
+						if altShift {
+							if len(r.buffer) < 7 {
+								return Event{Invalid, 0, nil}
+							}
+							*sz = 7
+							char = r.buffer[6]
+						}
+						switch char {
 						case 'A':
+							if alt {
+								return Event{AltUp, 0, nil}
+							}
+							if altShift {
+								return Event{AltSUp, 0, nil}
+							}
 							return Event{SUp, 0, nil}
 						case 'B':
+							if alt {
+								return Event{AltDown, 0, nil}
+							}
+							if altShift {
+								return Event{AltSDown, 0, nil}
+							}
 							return Event{SDown, 0, nil}
 						case 'C':
+							if alt {
+								return Event{AltRight, 0, nil}
+							}
+							if altShift {
+								return Event{AltSRight, 0, nil}
+							}
 							return Event{SRight, 0, nil}
 						case 'D':
+							if alt {
+								return Event{AltLeft, 0, nil}
+							}
+							if altShift {
+								return Event{AltSLeft, 0, nil}
+							}
 							return Event{SLeft, 0, nil}
 						}
 					} // r.buffer[4]

src/tui/tcell.go

@@ -222,7 +222,10 @@ func (r *FullscreenRenderer) GetChar() Event {
 
 		// process keyboard:
 	case *tcell.EventKey:
-		alt := (ev.Modifiers() & tcell.ModAlt) > 0
+		mods := ev.Modifiers()
+		alt := (mods & tcell.ModAlt) > 0
+		shift := (mods & tcell.ModShift) > 0
+		altShift := alt && shift
 		keyfn := func(r rune) int {
 			if alt {
 				return CtrlAltA - 'a' + int(r)
@@ -297,21 +300,45 @@ func (r *FullscreenRenderer) GetChar() Event {
 			return Event{BSpace, 0, nil}
 
 		case tcell.KeyUp:
+			if altShift {
+				return Event{AltSUp, 0, nil}
+			}
+			if shift {
+				return Event{SUp, 0, nil}
+			}
 			if alt {
 				return Event{AltUp, 0, nil}
 			}
 			return Event{Up, 0, nil}
 		case tcell.KeyDown:
+			if altShift {
+				return Event{AltSDown, 0, nil}
+			}
+			if shift {
+				return Event{SDown, 0, nil}
+			}
 			if alt {
 				return Event{AltDown, 0, nil}
 			}
 			return Event{Down, 0, nil}
 		case tcell.KeyLeft:
+			if altShift {
+				return Event{AltSLeft, 0, nil}
+			}
+			if shift {
+				return Event{SLeft, 0, nil}
+			}
 			if alt {
 				return Event{AltLeft, 0, nil}
 			}
 			return Event{Left, 0, nil}
 		case tcell.KeyRight:
+			if altShift {
+				return Event{AltSRight, 0, nil}
+			}
+			if shift {
+				return Event{SRight, 0, nil}
+			}
 			if alt {
 				return Event{AltRight, 0, nil}
 			}

src/tui/tui.go

@@ -98,6 +98,11 @@ const (
 	AltLeft
 	AltRight
 
+	AltSUp
+	AltSDown
+	AltSLeft
+	AltSRight
+
 	Alt0
 )