add new example 'debug-ui' (to be integrated in your mobile app)

examples/debug-ui/lisp/d-input-hook.lisp

@@ -0,0 +1,53 @@
+;;; idea & most code from "ecl-readline.lisp"
+
+(defpackage input-hook
+  (:use :cl)
+  (:export
+   #:add))
+
+(provide :input-hook)
+
+(in-package :input-hook)
+
+(defvar *functions* nil)
+
+(defun add (function)
+  (let ((stream (make-instance 'input-hook-stream)))
+    (push (cons stream function) *functions*)
+    stream))
+
+(defclass input-hook-stream (gray:fundamental-character-input-stream)
+  ((buffer :initform (make-string 0))
+   (index  :initform 0)))
+
+(defmethod gray:stream-read-char ((stream input-hook-stream))
+  (if (ensure-stream-data stream)
+      (with-slots (buffer index) stream
+        (let ((ch (char buffer index)))
+          (incf index)
+          ch))
+      :eof))
+
+(defmethod gray:stream-unread-char ((stream input-hook-stream) character)
+  (with-slots (index) stream
+    (when (> index 0)
+      (decf index))))
+
+(defmethod gray:stream-listen ((stream input-hook-stream))
+  nil)
+
+(defmethod gray:stream-clear-input ((stream input-hook-stream))
+  nil)
+
+(defmethod gray:stream-peek-char ((stream input-hook-stream))
+  (if (ensure-stream-data stream)
+      (with-slots (buffer index) stream
+        (char buffer index))
+      :eof))
+
+(defun ensure-stream-data (stream)
+  (with-slots (buffer index) stream
+    (when (= index (length buffer))
+      (setf buffer (funcall (cdr (assoc stream *functions*)))
+            index 0))
+    buffer))