Implemented terminal.getch() for Windows

lib/pure/terminal.nim

@@ -493,17 +493,26 @@ template styledEcho*(args: varargs[expr]): expr =
   ## Echoes styles arguments to stdout using ``styledWriteLine``.
   callStyledEcho(args)
 
-when defined(nimdoc):
-  proc getch*(): char =
-    ## Read a single character from the terminal, blocking until it is entered.
-    ## The character is not printed to the terminal. This is not available for
-    ## Windows.
-    discard
-elif not defined(windows):
-  proc getch*(): char =
-    ## Read a single character from the terminal, blocking until it is entered.
-    ## The character is not printed to the terminal. This is not available for
-    ## Windows.
+proc getch*(): char =
+  ## Read a single character from the terminal, blocking until it is entered.
+  ## The character is not printed to the terminal.
+  when defined(windows):
+    let fd = getStdHandle(STD_INPUT_HANDLE)
+    # Block until character is entered
+    discard waitForSingleObject(fd, INFINITE)
+    var record = INPUT_RECORD()
+    var recordPtr: ptr INPUT_RECORD = addr(record)
+    var numRead: cint 
+    while true:
+      discard readConsoleInput(fd, recordPtr, 1, addr(numRead))
+      if numRead == 0 or record.eventType != 1:
+        continue
+      let keyEvent = cast[ptr KEY_EVENT_RECORD](recordPtr)
+      # skip key release events
+      if keyEvent.bKeyDown == 0:
+        continue
+      return char(keyEvent.UnicodeChar)
+  else:
     let fd = getFileHandle(stdin)
     var oldMode: Termios
     discard fd.tcgetattr(addr oldMode)

lib/windows/winlean.nim

@@ -1016,4 +1016,26 @@ proc wsaCloseEvent*(hEvent: Handle): bool
      {.stdcall, importc: "WSACloseEvent", dynlib: "ws2_32.dll".}
 
 proc wsaResetEvent*(hEvent: Handle): bool
-     {.stdcall, importc: "WSAResetEvent", dynlib: "ws2_32.dll".}
+     {.stdcall, importc: "WSAResetEvent", dynlib: "ws2_32.dll".}
+
+type
+  INPUT_RECORD* {.final, pure.} = object
+    eventType*: int16
+    padding: array[18, byte]
+  KEY_EVENT_RECORD* {.final, pure.} = object
+    eventType*: int16
+    bKeyDown*: WINBOOL
+    wRepeatCount*: int16
+    wVirtualKeyCode*: int16
+    wVirtualScanCode*: int16
+    UnicodeChar*: int16
+    dwControlKeyState*: DWORD
+
+when defined(useWinAnsi):
+  proc readConsoleInput*(hConsoleInput: Handle, lpBuffer: pointer, nLength: cint,
+                        lpNumberOfEventsRead: ptr cint): cint
+       {.header: "<windows.h>", importc: "ReadConsoleInputA".}
+else:
+  proc readConsoleInput*(hConsoleInput: Handle, lpBuffer: pointer, nLength: cint,
+                        lpNumberOfEventsRead: ptr cint): cint
+       {.header: "<windows.h>", importc: "ReadConsoleInputW".}