X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/a1985b3cf0ca42f573b8599ec50a0f162a26c314..6afec9101d5ea87e3df4bda2239ffd05f8154fa6:/src/fragment-parse.lisp

diff --git a/src/fragment-parse.lisp b/src/fragment-parse.lisp
index c958da3..fcaa92e 100644
--- a/src/fragment-parse.lisp
+++ b/src/fragment-parse.lisp
@@ -40,9 +40,9 @@
    takes into account comments (both C and C++ style), string and character
    literals."
 
-  (let ((char-scanner (token-scanner-char-scanner scanner))
-	(delim nil)
-	(stack nil))
+  (let* ((char-scanner (token-scanner-char-scanner scanner))
+	 (delim-match nil) (delim-found nil) (delim-loc nil)
+	 (stack nil) (start nil) (tokstart nil) (eofwhine t))
     (with-parser-context (character-scanner-context :scanner char-scanner)
 
       ;; Hack.  If the first character is a newline then discard it
@@ -51,11 +51,20 @@
       (parse #\newline)
 
       ;; This seems the easiest way of gathering stuff.
+      (setf start (file-location char-scanner))
       (with-scanner-place (place char-scanner)
 
-	(flet ((push-delim (d)
-		 (push delim stack)
-		 (setf delim d))
+	(flet ((push-delim (found match)
+		 (push (list delim-found delim-match delim-loc) stack)
+		 (setf delim-found found
+		       delim-match match
+		       delim-loc tokstart))
+
+	       (pop-delim ()
+		 (destructuring-bind (found match loc) (pop stack)
+		   (setf delim-found found
+			 delim-match match
+			 delim-loc loc)))
 
 	       (result ()
 		 (let* ((output (scanner-interval char-scanner place))
@@ -71,6 +80,7 @@
 
 	  ;; March through characters until we reach the end.
 	  (loop
+	    (setf tokstart (file-location char-scanner))
 	    (cond-parse (:consumedp cp :expected exp)
 
 	      ;; Whitespace and comments are universally dull.
@@ -80,31 +90,58 @@
 	      ;; See if we've reached the end.  We must leave the delimiter
 	      ;; in the scanner, so `if-char' and its various friends aren't
 	      ;; appropriate.
-	      ((lisp (if (and (null delim)
+	      ((lisp (if (and (null delim-match)
+			      (not (scanner-at-eof-p char-scanner))
 			      (member (scanner-current-char char-scanner)
 				      end-chars))
 			 (values (result) t t)
 			 (values end-chars nil nil)))
 	       (return (values it t t)))
 	      (:eof
-	       (lexer-error char-scanner '(:any))
+	       (when eofwhine
+		 (lexer-error char-scanner nil))
+	       (loop
+		 (unless delim-found (return))
+		 (info-with-location delim-loc
+				     "Unmatched `~C' found here" delim-found)
+		 (pop-delim))
+	       (info-with-location start "C fragment started here")
 	       (return (values (result) t t)))
 
 	      ;; Opening and closing brackets.  Opening brackets push things
-	      ;; onto a stack; closing brackets pop things off again.
-	      (#\( (push-delim #\)))
-	      (#\[ (push-delim #\]))
-	      (#\{ (push-delim #\}))
-	      ((or #\) #\] #\})
-	       (if (eql it delim)
-		   (setf delim (pop stack))
-		   (cerror* "Unmatched `~C'" it)))
+	      ;; onto a stack; closing brackets pop things off again.  Pop a
+	      ;; bracket even if it doesn't match, to encourage progress
+	      ;; towards finding an end-delimiter.
+	      (#\( (push-delim #\( #\)))
+	      (#\[ (push-delim #\[ #\]))
+	      (#\{ (push-delim #\{ #\}))
+	      ((lisp (let ((char (scanner-current-char char-scanner)))
+		       (case char
+			 ((#\) #\] #\})
+			  (unless (eql char delim-match)
+			    (lexer-error char-scanner
+					 (and delim-match
+					      (list delim-match)))
+			    (when delim-loc
+			      (info-with-location
+			       delim-loc
+			       "Mismatched `~C' found here" delim-found)))
+			  (scanner-step char-scanner)
+			  (when delim-match (pop-delim))
+			  (values char t t))
+			 (t
+			  (values '(#\) #\] #\}) nil nil))))))
 
 	      ;; String and character literals.
 	      ((seq ((quote (or #\" #\'))
 		     (nil (skip-many ()
-			      (or (and #\\ :any) (not quote))))
-		     (nil (char quote)))))
+			    (or (and #\\ :any) (not quote))))
+		     (nil (or (char quote)
+			      (seq (:eof)
+				(lexer-error char-scanner (list quote))
+				(info-with-location tokstart
+						    "Literal started here")
+				(setf eofwhine nil)))))))
 
 	      ;; Anything else.
 	      (:any)
@@ -112,6 +149,8 @@
 	      ;; This really shouldn't be able to happen.
 	      (t
 	       (assert cp)
+	       (when (scanner-at-eof-p char-scanner)
+		 (setf eofwhine nil))
 	       (lexer-error char-scanner exp)))))))))
 
 (export 'parse-delimited-fragment)