From 1af10ddc10e35805c6723d7a2a85d7e3768497f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Juan=20Manuel=20Tom=C3=A1s?= <jtomas1815@gmail.com>
Date: Sun, 13 Oct 2024 00:51:57 -0300
Subject: Error out on parser failure

---
 input.lisp   | 11 +++++++++++
 main.lisp    |  6 +++++-
 package.lisp |  1 +
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/input.lisp b/input.lisp
index e28e73a..100baa5 100644
--- a/input.lisp
+++ b/input.lisp
@@ -18,3 +18,14 @@
 
 (defun cursor-distance (input1 input2)
   (- (input-cursor input1) (input-cursor input2)))
+
+(defun line-and-column (input)
+  (let ((line 1) (column 1))
+    (dotimes (i (input-cursor input))
+      (let ((c (char (input-data input) i)))
+        (case c
+          (#\Newline
+           (incf line)
+           (setf column 1))
+          (t (incf column)))))
+    (values line column)))
diff --git a/main.lisp b/main.lisp
index 6357cc4..0d890a0 100644
--- a/main.lisp
+++ b/main.lisp
@@ -8,4 +8,8 @@
     (if (parsing-p result)
       (let ((finished? (not (has-data? (parsing-left result)))))
         (values (parsing-tree result) finished?))
-      result)))
+      (error (format nil "~a" result)))))
+
+(defmethod print-object ((obj failure) stream)
+  (multiple-value-bind (line column) (line-and-column (failure-place obj))
+    (format stream "~a:~a: ~a" line column (failure-message obj))))
diff --git a/package.lisp b/package.lisp
index c59f997..62846f2 100644
--- a/package.lisp
+++ b/package.lisp
@@ -5,6 +5,7 @@
            #:failure-message
            #:input-cursor
            #:input-data
+           #:line-and-column 
            #:comp
            #:one-of
            #:unit
-- 
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