fix: fix various errors in parser - especially nested win32-input-mode

This seems to fix things quite nicely for WezTerm regardless of
running remotely or locally on Windows, or on macOS.  The goofy
nesting level only needs to be done when dealing with nesting, and
we can be reasonably sure that all content requiring the extra
parse pass comes together and is complete (and is generally only
required for non-keyboard data.)

Author: gdamore

_demos/mouse.go

@@ -139,7 +139,7 @@ func main() {
 
 	for {
 		drawBox(s, 1, 1, 42, 8, style, ' ')
-		s.PutStrStyled(2, 2, "Press ESC twice to exit, C to clear.", style)
+		s.PutStrStyled(2, 2, "Press Ctrl-Q to Quit, C to clear.", style)
 		s.PutStrStyled(2, 3, fmt.Sprintf(posfmt, mx, my), style)
 		s.PutStrStyled(2, 4, fmt.Sprintf(btnfmt, bstr), style)
 		s.PutStrStyled(2, 5, fmt.Sprintf(keyfmt, lks), style)
@@ -196,6 +196,9 @@ func main() {
 				}
 			} else if ev.Key() == tcell.KeyCtrlL {
 				s.Sync()
+			} else if ev.Key() == tcell.KeyCtrlQ {
+				s.Fini()
+				os.Exit(0)
 			} else if ev.Key() == tcell.KeyCtrlZ {
 				// CtrlZ doesn't really suspend the process, but we use it to execute a subshell.
 				if err := s.Suspend(); err == nil {

input.go

@@ -584,7 +584,6 @@ func (ip *inputParser) scan() {
 			ip.post(NewEventKey(KeyEscape, "", ModNone))
 		} else if ec := ip.escChar; ec != 0 {
 			ip.post(NewEventKey(KeyRune, string(ec), ModAlt))
-		} else {
 		}
 		// if we take too long between bytes, reset the state machine.
 		ip.state = istInit
@@ -732,16 +731,21 @@ func (ip *inputParser) handleWinKey(P []int) {
 		// key up event ignore ignore
 		return
 	}
-	if P[0] == 0 && P[2] == 27 && ip.nested == nil {
-		ip.nested = &inputParser{
-			evch: ip.evch,
-			rows: ip.rows,
-			cols: ip.cols,
-		}
-	}
 
-	if ip.nested != nil && P[2] > 0 && P[2] < 0x80 { // only ASCII in win32-input-mode
-		ip.nested.ScanUTF8([]byte{byte(P[2])})
+	// these terminals never send ambiguous escapes
+	ip.escaped = false
+
+	if P[0] == 0 && P[1] == 0 && P[2] > 0 && P[2] < 0x80 { // only ASCII in win32-input-mode
+		if ip.nested == nil {
+			ip.nested = &inputParser{
+				evch: ip.evch,
+				rows: ip.rows,
+				cols: ip.cols,
+			}
+		}
+		if P[2] > 0 {
+			ip.nested.ScanUTF8([]byte{byte(P[2])})
+		}
 		return
 	}
 
@@ -814,6 +818,8 @@ func (ip *inputParser) handleCsi(mode rune, params []byte, intermediate []byte)
 				if n, e := strconv.ParseInt(parts[i], 10, 32); e == nil {
 					P = append(P, int(n))
 				}
+			} else {
+				P = append(P, 0)
 			}
 		}
 	}
@@ -827,6 +833,7 @@ func (ip *inputParser) handleCsi(mode rune, params []byte, intermediate []byte)
 		case 'm', 'M': // mouse event, we only do SGR tracking
 			ip.handleMouse(mode, P)
 		}
+		return
 	}
 
 	switch mode {
@@ -841,8 +848,8 @@ func (ip *inputParser) handleCsi(mode rune, params []byte, intermediate []byte)
 		ip.state = istLnx
 		return
 	case 'u':
-		// CSI-u kitty keyboard protocol
-		if len(P) > 0 && !hasLT {
+		// CSI-u kitty keyboard protocol, is unambiguous
+		if len(P) > 0 {
 			mod := ModNone
 			key := KeyRune
 			chr := rune(0)
@@ -874,7 +881,7 @@ func (ip *inputParser) handleCsi(mode rune, params []byte, intermediate []byte)
 			return
 		}
 	case '~':
-		if len(P) >= 2 && !hasLT {
+		if len(P) >= 2 {
 			mod := calcModifier(P[1])
 			if ks, ok := csiAllKeys[csiParamMode{M: mode, P: P0}]; ok {
 				ip.post(NewEventKey(ks.Key, "", mod))
@@ -891,7 +898,7 @@ func (ip *inputParser) handleCsi(mode rune, params []byte, intermediate []byte)
 		}
 	}
 
-	if ks, ok := csiAllKeys[csiParamMode{M: mode, P: P0}]; ok && !hasLT {
+	if ks, ok := csiAllKeys[csiParamMode{M: mode, P: P0}]; ok {
 		if mode == '~' && len(P) > 1 && ks.Mod == ModNone {
 			// apply modifiers if present
 			ks.Mod = calcModifier(P[1])