failures
:initial-value nil))
+(export 'parse-empty)
+(defun parse-empty (&optional value)
+ "Return a parser which parses nothing, successfully.
+
+ The parser returns VALUE and consumes nothing."
+ (lambda () (values value t nil)))
+
+(export 'parse-fail)
+(defun parse-fail (indicator &optional consumedp)
+ "Return a parser which fails.
+
+ The parser reports the INDICATOR and (falsely) claims to have consumed
+ input if CONSUMEDP is true."
+ (lambda () (values indicator nil consumedp)))
+
;;;--------------------------------------------------------------------------
;;; Basic protocol.
The return value may later be used with `parser-restore-place'. Be
careful: all of this is happening at macro-expansion time.")
(:method (context)
- (error "Parser context ~S doesn't support rewinding." context)))
+ (error "Parser context ~S doesn't support rewinding" context)))
(export 'parser-restore-place)
(defgeneric parser-restore-place (context place)
(defun commit-peeked-place ()
"Called by `commit' not lexically within `peek'."
- (error "`commit' is not within `peek'."))
+ (error "`commit' is not within `peek'"))
(export 'commit)
(defparse commit ()