Update parser interface

1 files changed, 15 insertions, 4 deletions

diff --git a/main.lisp b/main.lisp
index 197f1b2..f802d25 100644
--- a/main.lisp
+++ b/main.lisp
@@ -6,9 +6,20 @@
                                          :data data))))
     (if (parsing-p result)
       (let ((finished? (not (has-data? (parsing-left result)))))
-        (values result finished?))
+        (values (parsing-tree result) finished?))
       result)))
 
-(defmethod print-object ((obj failure) stream)
-  (multiple-value-bind (line column) (line-and-column (failure-place obj))
-    (format stream "~a:~a: ~a~&~a" line column (failure-message obj) (failure-place obj))))
+(defun append-on-failure (p message)
+  (lambda (input)
+    (let ((result (funcall p input)))
+      (if (failure-p result)
+        (make-failure :place (failure-place result)
+                      :message (concatenate 'string message (failure-message result))
+                      :priority (failure-priority result))
+        result))))
+
+(defmacro defparser (name args parser)
+  (let ((message (format nil "In ~a:~&" name)))
+    (if (null args)
+      `(defparameter ,name (append-on-failure ,parser ,message))
+      `(defun ,name ,args (append-on-failure ,parser ,message)))))