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(in-package #:monparser)
(defun parse-string (p input)
(let ((result (funcall p (from-string input))))
(if (parsing-p result)
(parsing-tree result)
result)))
(defun parse-file (p input)
(let ((result (funcall p (from-file input))))
(if (parsing-p result)
(parsing-tree result)
result)))
(defstruct parsing
tree
left)
(defstruct failure
place
message)
(defmethod print-object ((obj failure) stream)
(let ((file (file (failure-place obj))))
(if file
(multiple-value-bind (line column) (line-and-column (failure-place obj))
(format stream "~a:~a:~a: ~a" line column file (failure-message obj)))
(format stream "~a: ~a" (cursor (failure-place obj)) (failure-message obj)))))
(defun new (tree)
(lambda (input &key limit lazy)
(declare (ignore lazy limit))
(make-parsing :tree tree :left input)))
; (parser<a> (a -> parser<b>) -> b)
(defun bind (p f &key (greedy t))
(lambda (input &key limit lazy)
(let (r)
(if greedy
(setf r (funcall p input))
(let ((next-parser (funcall f nil input))
(limit -1))
(do ((sweep-input input (advance sweep-input))) (limit nil)
(when (and (has-data? sweep-input)
(functionp (funcall next-parser sweep-input t)))
(setf limit (input-sub sweep-input input))))
(if (< limit 0)
(setf r (make-failure :place input
:message "Reached end of input while sweeping."))
(setf r (funcall p input :limit limit)))))
(if (parsing-p r)
(if lazy
(lambda (ignored-input &key lazy inner-limit)
(declare (ignore ignored-input inner-limit))
(funcall (funcall f (parsing-tree r) input)
(parsing-left r)
:lazy lazy
:limit (if limit (1- limit))))
(funcall (funcall f (parsing-tree r) input)
(parsing-left r)
:limit (if limit (1- limit))))
r))))
(defmacro comp (bindings &body body)
(if (null bindings)
`(new (progn ,@body))
(let ((v (first (car bindings)))
(p (second (car bindings)))
(unused (gensym)))
(if (symbolp v)
(if (string= (symbol-name v) "_")
`(bind ,p (lambda (&rest ,unused)
(declare (ignore ,unused))
(comp ,(cdr bindings) ,@body)))
`(bind ,p (lambda (,v &rest ,unused)
(declare (ignore ,unused))
(comp ,(cdr bindings) ,@body))))
(if (and (consp v) (symbolp (car v)) (symbolp (cdr v)))
`(bind ,p (lambda (,(car v) ,(cdr v) &rest ,unused)
(declare (ignore ,unused))
(comp ,(cdr bindings) ,@body)))
(error "Binding must be either a symbol or a cons of symbols."))))))
(defun one-of (first-parser second-parser &rest other-parsers)
(lambda (input &key limit lazy)
(declare (ignore lazy limit))
(labels ((one-of-rec (parsers)
(let ((intermediate-parsers '())
(result nil))
(dolist (p parsers)
(let ((r (funcall p input :lazy (> (length parsers) 1))))
(cond ((functionp r)
(push r intermediate-parsers))
((parsing-p r)
(when (or (not (parsing-p result))
(> (cursor (parsing-input r))
(cursor (parsing-input result))))
(setf result r)))
((failure-p r)
(when (or (failure-p result)
(= (length parsers) 1))
(setf result r))))))
(if intermediate-parsers
(one-of-rec intermediate-parsers)
result))))
(one-of-rec (cons first-parser (cons second-parser other-parsers))))))
(defmacro unit (&optional predicate)
(cond ((null predicate)
(setf predicate '(characterp it)))
((symbolp predicate)
(setf predicate `(,predicate it)))
((characterp predicate)
(setf predicate `(char-equal ,predicate it)))
(t (setf predicate
(nsubst-if 'it
(lambda (x)
(and (symbolp x)
(string-equal (symbol-name x) "IT"))) predicate))))
`(lambda (input &key limit lazy)
(declare (ignore lazy limit))
(if (has-data? input)
(let ((it (peek input)))
(if ,predicate
(make-parsing :tree it :left (advance input))
(make-failure :place input
:message (format nil "Expected: ~a, Got: ~a" ',predicate it))))
(make-failure :place input :message "Reached end of input."))))
(defun literal (target)
(lambda (input &key limit lazy)
(declare (ignore lazy limit))
(if (has-data? input)
(if (prefix? target input)
(make-parsing :tree target :left (advance input (length target)))
(make-failure :place input :message "Predicate not satisfied."))
(make-failure :place input :message "Reached end of input."))))
(defparameter nothing
(new nil))
(defun optional (p)
(one-of p nothing))
(defun many (p)
(comp ((x p)
(xs (optional (many p))))
(cons x xs)))
(defun repeat (p min &optional (max 0))
(if (> min 0)
(comp ((x p)
(xs (repeat p (1- min) (1- max))))
(cons x xs))
(if (> max 0)
(comp ((x (optional p))
(xs (repeat p 0 (if x (1- max) 0))))
(if x (cons x xs) x))
nothing)))
(defun whitespace? (x)
(some (lambda (y) (char= x y)) '(#\Space #\Newline #\Tab)))
(defparameter whitespace
(comp ((_ (optional (many (unit whitespace?)))))
nil))
(defun separated-list (p separator &key include-separator)
(comp ((v p)
(sep (optional separator))
(vn (if sep
(crit (separated-list p separator))
nothing)))
(if include-separator
(cons v (cons sep vn))
(cons v vn))))
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