X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/sod/blobdiff_plain/dea4d05507e59ab779ed4bb209e05971d87e260c..bf090e021a5c20da452a4841cdfb8eb78e29544e:/src/parser/impl-scanner-token.lisp

diff --git a/src/parser/impl-scanner-token.lisp b/src/parser/impl-scanner-token.lisp
index e058b27..bf5e394 100644
--- a/src/parser/impl-scanner-token.lisp
+++ b/src/parser/impl-scanner-token.lisp
@@ -39,22 +39,23 @@ (defmethod scanner-at-eof-p ((scanner token-scanner))
 
 (defmethod scanner-step ((scanner token-scanner))
   (with-slots (type value tail captures line column) scanner
-    (cond (tail
-	   (let ((next (token-scanner-place-next tail)))
-	     (setf type (token-scanner-place-type next)
-		   value (token-scanner-place-value next)
-		   line (token-scanner-place-line next)
-		   column (token-scanner-place-column next)
-		   tail next)))
-	  (t
-	   (multiple-value-bind (ty val) (scanner-token scanner)
-	     (setf type ty
-		   value val)
-	     (when (plusp captures)
-	       (let ((next (make-token-scanner-place
-			    :type ty :value val :line line :column column)))
-		 (setf (token-scanner-place-next tail) next
-		       tail next))))))))
+    (acond ((and tail (token-scanner-place-next tail))
+	    (setf type (token-scanner-place-type it)
+		  value (token-scanner-place-value it)
+		  line (token-scanner-place-line it)
+		  column (token-scanner-place-column it)
+		  tail it))
+	   (t
+	    (multiple-value-bind (ty val) (scanner-token scanner)
+	      (setf type ty
+		    value val)
+	      (if (plusp captures)
+		  (let ((next (make-token-scanner-place
+			       :type ty :value val
+			       :line line :column column)))
+		    (setf (token-scanner-place-next tail) next
+			  tail next))
+		  (setf tail nil)))))))
 
 (defmethod scanner-capture-place ((scanner token-scanner))
   (with-slots (type value captures tail line column) scanner