Better explicit control over utf-8 input mode

ansi/lcd-terminal.rkt

@@ -145,7 +145,7 @@
    [(<= #x20 b #x7e) (simple-key (integer->char b))]
    [(= b #x7f) (simple-key 'backspace)]))
 
-(define (lex-lcd-input port)
+(define (lex-lcd-input port #:utf-8? [utf-8? (lcd-terminal-utf-8?)])
   (cond
    [(eof-object? (peek-byte port)) eof]
    [(or (regexp-try-match #px"^\e\\[([0-9]+(;[0-9]+)*)?(.)" port)
@@ -168,8 +168,8 @@
    ;; Characters between #\u80 and #\uff are ambiguous because in
    ;; some terminals, the high bit is set to indicate meta, and in
    ;; others, they are plain UTF-8 characters. We let the user
-   ;; distinguish via the lcd-terminal-utf-8? parameter.
-   [(not (lcd-terminal-utf-8?))
+   ;; distinguish via the #:utf-8? keyword argument.
+   [(not utf-8?)
     (define b (read-byte port))
     (if (< b 128)
         (interpret-ascii-code b)

ansi/test-raw.rkt

@@ -9,6 +9,12 @@
 (define (main)
   (tty-raw!)
 
+  (define utf-8?
+    (match (current-command-line-arguments)
+      [(or '#() '#("--utf-8")) #t]
+      ['#("--no-utf-8") #f]
+      [_ (error 'main "Usage: test-raw [ --utf-8 / --no-utf-8 ]")]))
+
   (plumber-add-flush! (current-plumber)
                       (lambda (handle)
                         (display (reset-mode x11-any-event-mouse-tracking-mode))))
@@ -19,7 +25,7 @@
   (display "Type keys. Press control-D to exit.\r\n")
   (let loop ()
     (flush-output)
-    (match (lex-lcd-input (current-input-port))
+    (match (lex-lcd-input (current-input-port) #:utf-8? utf-8?)
       [(? eof-object?) (void)]
       [(== (key #\D (set 'control))) (void)]
       [key

rmacs/display.rkt

@@ -58,6 +58,7 @@
              key-reader ;; InputPort -> Key
              [displayed-screen #:mutable] ;; Screen
              [pending-screen #:mutable] ;; Screen
+             [utf-8-input? #:mutable] ;; Boolean
              ) #:prefab)
 
 (define (make-screen rows columns pen)
@@ -80,7 +81,14 @@
                (current-output-port)
                ansi:lex-lcd-input
                (make-screen 24 80 tty-default-pen)
-               (make-screen 24 80 tty-default-pen)))
+               (make-screen 24 80 tty-default-pen)
+               (match (getenv "RMACS_UTF8_INPUT")
+                 [(or #f "yes" "true" "1") #t]
+                 [(or "no" "false" "0") #f]
+                 [v (error 'RMACS_UTF8_INPUT
+                           "Environment variable RMACS_UTF8_INPUT value ~v invalid: must be in ~v"
+                           v
+                           (list "yes" "true" "1" "no" "false" "0"))])))
     (reset *stdin-tty*)
     (plumber-add-flush! (current-plumber)
                         (lambda (h)
@@ -360,7 +368,7 @@
 ;; Input
 
 (define (tty-next-key tty)
-  (define k (ansi:lex-lcd-input (tty-input tty)))
+  (define k (ansi:lex-lcd-input (tty-input tty) #:utf-8? (tty-utf-8-input? tty)))
   (if (equal? k (ansi:key #\[ (set 'control))) ;; ESC
       (or (sync/timeout 0.5
                         (handle-evt (tty-next-key-evt tty)