1 files changed, 33 insertions, 0 deletions
diff --git a/src/prompt.lisp b/src/prompt.lisp
new file mode 100644
index 0000000..afe8604
--- /dev/null
+++ b/src/prompt.lisp
@@ -0,0 +1,33 @@
+;;;; prompt.lisp -- a function using readlline to collect text from the user
+
+(defpackage #:oneliners.cli.prompt
+  (:use #:cl)
+  (:local-nicknames (#:rl #:cl-readline))
+  (:export #:prompt))
+
+(in-package :oneliners.cli.prompt)
+
+(defun prompt (prompt
+               &key
+                 (expect (constantly t))
+                 retry-text
+                 (prefill ""))
+  ;; register a prefill hook
+  (rl:register-hook
+   :pre-input
+   (lambda ()
+     (rl:insert-text prefill)
+     (rl:redisplay)))
+  (unwind-protect 
+       (loop
+         with prompt-text = prompt
+         with should-retry-p = t
+         while should-retry-p
+         for line = (rl:readline :prompt prompt-text)
+         when (funcall expect line)
+           do (setf should-retry-p nil)
+         when retry-text
+           do (setf prompt-text retry-text)
+         finally (return line))
+    ;; unregisters the hook.
+    (rl:register-hook :pre-input nil)))