1 files changed, 40 insertions, 0 deletions
diff --git a/input.lisp b/input.lisp
new file mode 100644
index 0000000..d6dd4b3
--- /dev/null
+++ b/input.lisp
@@ -0,0 +1,40 @@
+(in-package #:input)
+
+(defstruct input
+  (cursor 0)
+  (file nil :read-only t)
+  (data nil :read-only t))
+
+(defun has-data? (input)
+  (< (input-cursor input)
+     (length (input-data input))))
+
+(defun element (input)
+  (char (input-data input)
+        (input-cursor input)))
+
+(defun advance (input)
+  (let ((new-input (copy-structure input)))
+    (incf (input-cursor new-input))
+    new-input))
+
+(declaim (ftype (function (simple-string) (values input &optional)) from-string))
+(defun from-string (str)
+  (make-input :data str))
+
+(declaim (ftype (function (simple-string) (values input &optional)) from-file))
+(defun from-file (filename)
+  (make-input :file filename :data (str:read-file filename)))
+
+(defun generate-report (input message)
+  (let ((line 0) (column 0))
+    (dotimes (i (input-cursor input))
+      (let ((c (char (input-data input) i)))
+        (case c
+          (#\Newline
+           (incf line)
+           (setf column 1))
+          (t (incf column)))))
+    (if (input-file input)
+      (format nil "~a:~a:~a: ~a" (input-file input) line column message)
+      (format nil "~a:~a: ~a" line column message))))