scaffolding for backspace functionality

fcore/normal-mode/normal-mode.sml

@@ -272,4 +272,5 @@ struct
     | WITH_SEARCH_LIST searchList =>
         NormalFinish.withSearchList (app, searchList)
     | KEY_ENTER => app
+    | KEY_BACKSPACE => app
 end

fcore/normal-mode/normal-search-mode.sml

@@ -110,9 +110,14 @@ struct
         (app, buffer, searchString, tempSearchList, startLine, mode, msgs)
     end
 
+  (* todo: implement *)
+  fun backspace (app: app_type, searchString, tempSearchList) =
+    raise Fail "normal-search-mode: KEY_BACKSPACE unimplemented"
+
   fun update (app, {searchString, tempSearchList}, msg, time) =
     case msg of
       CHAR_EVENT chr => addChr (app, searchString, chr)
+    | KEY_BACKSPACE => backspace (app, searchString, tempSearchList)
     | KEY_ESC => exitToNormalMode app
     | KEY_ENTER => saveSearch (app, searchString, tempSearchList)
     | RESIZE_EVENT (width, height) => app

ffi/glfw-input.c

@@ -8,6 +8,7 @@ int REPEAT = GLFW_REPEAT;
 int RELEASE = GLFW_RELEASE;
 int KEY_ESC = GLFW_KEY_ESCAPE;
 int KEY_ENTER = GLFW_KEY_ENTER;
+int KEY_BACKSPACE = GLFW_KEY_BACKSPACE;
 
 void framebufferSizeCallback(GLFWwindow* window, int width, int height) {
   glViewport(0, 0, width, height);

ffi/glfw-input.sml

@@ -36,4 +36,7 @@ struct
   val (KEY_ENTER, _) =
     _symbol "KEY_ENTER" public : ( unit -> int ) * ( int -> unit );
   val KEY_ENTER = KEY_ENTER ()
+  val (KEY_BACKSPACE, _) =
+    _symbol "KEY_BACKSPACE" public : ( unit -> int ) * ( int -> unit );
+  val KEY_BACKSPACE = KEY_BACKSPACE ()
 end

message-types/input-msg.sml

@@ -4,6 +4,7 @@ struct
     CHAR_EVENT of char
   | KEY_ESC
   | KEY_ENTER
+  | KEY_BACKSPACE
   | RESIZE_EVENT of int * int
   | WITH_SEARCH_LIST of int vector
 end

shell/shell.sml

@@ -27,6 +27,8 @@ struct
         Mailbox.send (inputMailbox, InputMsg.KEY_ESC)
       else if key = KEY_ENTER andalso action = PRESS andalso mods = 0 then
         Mailbox.send (inputMailbox, InputMsg.KEY_ENTER)
+      else if key = KEY_BACKSPACE andalso action <> RELEASE andalso mods = 0 then
+        Mailbox.send (inputMailbox, InputMsg.KEY_BACKSPACE)
       else
         ()
     end