X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/239fa5bd3dff0b38b0cebdd3438311f21c24ba4f..678b6c0f7fe1d62abdf249b173a8a922c4e5c1d3:/src/lexer-impl.lisp

diff --git a/src/lexer-impl.lisp b/src/lexer-impl.lisp
index f474590..7e953ef 100644
--- a/src/lexer-impl.lisp
+++ b/src/lexer-impl.lisp
@@ -7,7 +7,7 @@
 
 ;;;----- Licensing notice ---------------------------------------------------
 ;;;
-;;; This file is part of the Sensble Object Design, an object system for C.
+;;; This file is part of the Sensible Object Design, an object system for C.
 ;;;
 ;;; SOD is free software; you can redistribute it and/or modify
 ;;; it under the terms of the GNU General Public License as published by
@@ -39,9 +39,6 @@
 ;;;--------------------------------------------------------------------------
 ;;; Indicators and error messages.
 
-(defvar *indicator-map* (make-hash-table)
-  "Hash table mapping indicator objects to human-readable descriptions.")
-
 (defun show-char (stream char &optional colonp atsignp)
   "Format CHAR to STREAM in a readable way.
 
@@ -52,6 +49,45 @@
 	 (format stream "`~C'" char))
 	(t (format stream "<~(~:C~)>" char))))
 
+(defun skip-until (scanner token-types &key keep-end)
+  "This is the implementation of the `skip-until' parser."
+  (do ((consumedp nil t))
+      ((member (token-type scanner) token-types)
+       (unless keep-end (scanner-step scanner))
+       (values nil t (or keep-end consumedp)))
+    (when (scanner-at-eof-p scanner)
+      (return (values token-types nil consumedp)))
+    (scanner-step scanner)))
+
+(defun parse-error-recover (scanner parser recover &key ignore-unconsumed)
+  "This is the implementation of the `error' parser."
+  (multiple-value-bind (result win consumedp) (funcall parser)
+    (cond ((or win
+	       (and (not consumedp)
+		    (or ignore-unconsumed
+			(scanner-at-eof-p scanner))))
+	   ;; If we succeeded, or if we didn't consume any tokens and the
+	   ;; caller's OK with that, then there's nothing for us to do here.
+	   ;; On the other hand, if we failed, didn't consume any tokens, and
+	   ;; we're at end-of-file, then there's not much hope of making
+	   ;; onward progress, so in this case we propagate the failure
+	   ;; rather than trying to recover.  And we assume that the
+	   ;; continuation will somehow arrange to report the problem, and
+	   ;; avoid inundating the user with error reports.
+	   (values result win consumedp))
+	  (t
+	   ;; Now we have to do some kind of sensible error recovery.  The
+	   ;; important thing to do here is to make sure that we make some
+	   ;; progress.  If we consumed any tokens then we're fine, and we'll
+	   ;; just try the provided recovery strategy.  Otherwise, if we're
+	   ;; not at EOF, then we can ensure progress by discarding the
+	   ;; current token.  Finally, if we are at EOF then our best bet is
+	   ;; simply to propagate the current failure back to the caller, but
+	   ;; we handled that case above.
+	   (syntax-error scanner result :continuep t)
+	   (unless consumedp (scanner-step scanner))
+	   (funcall recover)))))
+
 ;;;--------------------------------------------------------------------------
 ;;; Token scanning.