diff options
Diffstat (limited to 'parser.lisp')
| -rw-r--r-- | parser.lisp | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/parser.lisp b/parser.lisp index a1ef1a8..2da9975 100644 --- a/parser.lisp +++ b/parser.lisp @@ -29,6 +29,13 @@ (funcall (funcall f (parsing-tree r)) (parsing-left r)) r)))) +(defun discarding-bind (p q) + (lambda (input) + (let ((r (funcall p input))) + (if (parsing-p r) + (funcall q (parsing-left r)) + r)))) + (defun fail (&optional (message "Unknown error.")) (lambda (input) (make-critical-failure :place input :message message))) @@ -53,12 +60,12 @@ (make-normal-failure :place input :message "Predicate not satisfied."))) (make-normal-failure :place input :message "Reached end of input.")))) -(defun literal (predicate) +(defun literal (str) (lambda (input) - (if (input::has-data? input (length predicate)) - (let ((str (input::peek-n input (length predicate)))) - (if (string= predicate str) - (make-parsing :tree str :left (input::advance input (length predicate))) + (if (input::has-data? input (length str)) + (let ((c (input::peek-n input (length str)))) + (if (string= str c) + (make-parsing :tree c :left (input::advance input (length c))) (make-normal-failure :place input :message "Predicate not satisfied."))) (make-normal-failure :place input :message "Reached end of input.")))) @@ -68,7 +75,7 @@ (let ((v (first (car bindings))) (p (second (car bindings)))) (if (eq v '_) - `(bind ,p (lambda () (comp ,(cdr bindings) ,@body))) + `(discarding-bind ,p (comp ,(cdr bindings) ,@body)) `(bind ,p (lambda (,v) (comp ,(cdr bindings) ,@body))))))) (defparameter nothing |