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(in-package :parser-combinators)
;; single character parsers
(def-cached-parser digit?
"Parser: accept digit character"
(sat #'digit-char-p))
(def-cached-parser lower?
"Parser: accept lowercase character"
(sat #'lower-case-p))
(def-cached-parser upper?
"Parser: accept uppercase character"
(sat #'upper-case-p))
(def-cached-parser letter?
"Parser: accept alphabetic character"
(sat #'alpha-char-p))
(def-cached-parser alphanum?
"Parser: accept alphanumeric character"
(sat #'alphanumericp))
;; some usual lexical tokens
(def-cached-arg-parser whitespace? (&key (result-type nil) (accept-empty nil))
"Parser: accept a sequence of whitespace characters."
(between? (sat (rcurry #'member '(#\Space #\Newline #\ )))
(if accept-empty nil 1)
nil
result-type))
(def-cached-parser word?
"Parser: accept a string of alphanumeric characters"
(between? (alphanum?) 1 nil 'string))
(def-cached-parser pure-word?
"Parser: accept a string of alphabetic characters"
(between? (letter?) 1 nil 'string))
;; naive implementation using monadic combinators, unfortunately rather slow
;; (defun int? ()
;; "Parser: accept an integer"
;; (mdo (<- f (choice (mdo (char? #\-) (result #'-)) (result #'identity)))
;; (<- n (nat?))
;; (result (funcall f n))))
(def-cached-arg-parser nat? (&optional (radix 10))
"Parser: accept natural numbers"
(named-seq? (<- number (between? (sat (rcurry #'digit-char-p radix))
1 nil
'string))
(parse-integer number :radix radix)))
(def-cached-arg-parser int? (&optional (radix 10))
"Parser: accept an integer, return as integer."
(named-seq*
(<- sign (choices #\-
#\+
(result #\+)))
(<- number (nat? radix))
(let ((sign (if (eql sign #\+)
1
-1)))
(* sign number))))
(def-cached-arg-parser quoted? (&key (quote-char #\")
(left-quote-char nil)
(right-quote-char nil)
(escape-char #\\)
(include-quotes t))
"Parser: accept a string delimited with quote-char, possibly escaped by escape-char, possibly including quotation chars."
(let* ((left-quote-char (or left-quote-char quote-char))
(right-quote-char (or right-quote-char quote-char))
(gather-end-condition (if escape-char
(rcurry #'member (list right-quote-char escape-char))
(rcurry #'eql right-quote-char)))
(quoted-quote (when escape-char
(format nil "~a~a" escape-char right-quote-char)))
(internal-parser (if escape-char
(many* (choice1 (gather-if-not* gather-end-condition
:result-type 'string)
(named-seq* quoted-quote 'quote)))
(gather-if-not* gather-end-condition :result-type nil :accept-empty t))))
(named-seq*
(<- c1 (context?))
left-quote-char
(<- data internal-parser)
right-quote-char
(<- c4 (context?))
(if include-quotes
(context-interval c1 c4)
(with-output-to-string (str)
(iter (for datum in data)
(if (eql datum 'quote)
(princ right-quote-char str)
(princ datum str))))))))
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