X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/e0808c472145fc81e52898bc9ac289e10c4f4f41..4fd69126f8b52945e0a572d1cf4a347468c1ced5:/src/lexer-proto.lisp

diff --git a/src/lexer-proto.lisp b/src/lexer-proto.lisp
index 7ed7924..d6d33cb 100644
--- a/src/lexer-proto.lisp
+++ b/src/lexer-proto.lisp
@@ -116,7 +116,8 @@
 
 (export 'error)
 (defparse error (:context (context token-scanner-context)
-		 (&key) sub &optional (recover t))
+		 (&key ignore-unconsumed)
+		 sub &optional (recover t))
   "Try to parse SUB; if it fails then report an error, and parse RECOVER.
 
    This is the main way to recover from errors and continue parsing.  Even
@@ -126,10 +127,15 @@
    were never here.  Otherwise, try to recover in a sensible way so we can
    continue parsing.  The details of this recovery are subject to change, but
    the final action is generally to invoke the RECOVER parser and return its
-   result."
+   result.
+
+   If IGNORE-UNCONSUMED evaluates non-nil, then just propagate a failure of
+   SUB if it didn't consume input.  (This makes it suitable for use where the
+   parser containing `error' might be optional.)"
   `(parse-error-recover ,(parser-scanner context)
 			(parser () ,sub)
-			(parser () ,recover)))
+			(parser () ,recover)
+			:ignore-unconsumed ,ignore-unconsumed))
 
 ;;;--------------------------------------------------------------------------
 ;;; Lexical analysis utilities.