Implement simple REPL

src/ncurses/Readline.ml

 
 external set_readline_name : string -> unit = "set_readline_name"
 external readline : unit -> string option = "readline_stub"
+external readline_prompt : string -> string option = "readline_prompt_stub"
 external add_history  : string -> unit = "add_history_stub"
 external connect_to_curses : unit -> unit = "connect_to_curses"
 external line_buffer : unit -> string = "line_buffer_stub"

src/ncurses/Readline.mli

@@ -2,6 +2,7 @@
 
 val set_readline_name : string -> unit
 val readline : unit -> string option
+val readline_prompt : string -> string option
 val add_history  : string -> unit
 val connect_to_curses : unit -> unit
 val line_buffer : unit -> string

src/ncurses/Readline_stub.c

@@ -17,6 +17,7 @@ extern "C" {
 
 value set_readline_name(value name);
 value readline_stub(value unit);
+value readline_prompt_stub(value prompt);
 value add_history_stub(value str);
 value connect_to_curses(value unit);
 value readline_use_ocaml_callback(value unit);
@@ -62,7 +63,21 @@ value readline_stub(value unit) {
   if (line == NULL) {
     CAMLreturn( Val_none );
   } else {
-    line_data = caml_alloc_string(strlen(line)+1);
+    line_data = caml_alloc_string(strlen(line));
+    strcpy( String_val(line_data), line);
+    free(line);
+    CAMLreturn( Val_some( line_data ) );
+  }
+}
+
+value readline_prompt_stub(value prompt) {
+  CAMLparam1 (prompt);
+  CAMLlocal1( line_data );
+  char* line = readline(String_val(prompt));
+  if (line == NULL) {
+    CAMLreturn( Val_none );
+  } else {
+    line_data = caml_alloc_string(strlen(line));
     strcpy( String_val(line_data), line);
     free(line);
     CAMLreturn( Val_some( line_data ) );

src/ncurses/Repl.ml

+
+open Readline
+
+type binding = string * (unit -> unit)
+
+type settings = {
+    prompt: string;
+    bindings: binding list;
+}
+
+let session : settings option ref = ref (None)
+
+let bind a b = (a,b)
+
+(* (* for debugging purposes... *)
+let cmp a b =
+    print_endline ("First string: >"^a^"<");
+    print_endline ("First string: >"^b^"<");
+    print_endline ("a=b -> >"^(string_of_bool (a = b))^"<");
+    print_endline ("a==b -> >"^(string_of_bool (a == b))^"<");
+    print_endline ("a<>b -> >"^(string_of_bool (a <> b))^"<")
+*)
+
+let start (settings: settings): unit =
+    session := Some (settings);
+    let findBinding (name: string) : binding =
+        let checkname (n,_) = (name = n) in
+        List.find checkname (settings.bindings)
+    in
+    let rec loop () =
+        if (!session = None) then ()
+        else begin
+            match (readline_prompt settings.prompt) with
+            | None -> ()
+            | Some line -> begin
+                let cmd = Str.split (Str.regexp "[ \n\t]+") line in
+                (match cmd with
+                | [] -> ()
+                | (v::_) when v = "" -> ()
+                | (name:: args) ->
+                    try
+                      let (_,callback) = findBinding name in
+                      callback()
+                    with Not_found -> begin
+                      let msg = "Command »"^name^"« not found." in
+                      print_endline msg
+                    end
+                )
+            end;
+            loop()
+        end
+    in
+    loop()
+
+let stop () =
+    session := None
+

src/ncurses/Repl.mli

+
+
+type binding = string * (unit -> unit)
+
+type settings = {
+    prompt: string;
+    bindings: binding list;
+}
+
+val bind : string -> (unit -> unit) -> binding
+
+val start : settings -> unit
+val stop : unit -> unit
+

src/repl-example/repl-example.ml

@@ -28,4 +28,14 @@ let main3 () =
     Unix.sleep 3;
     NCUI.screen_close()
 
-let _ = main3 ()
+let main4 () =
+    let session = {
+      Repl.prompt = "> ";
+      Repl.bindings = [
+        Repl.bind "exit" (fun () -> Repl.stop())
+      ];
+    }
+    in
+    Repl.start session
+
+let _ = main4 ()