/usr/share/common-lisp/source/lexer/lexer.lisp is in cl-lexer 1-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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(in-package :LEXER)
;;;
;;; tokenizer/lexical analyser generator
;;;
;;;
;;; TOKENIZE
;;;
;;; Similar to MATCH-CASE, but more explicitly tailored to parsing
;;; duties.
;;;
;
; Should probably take advantage of the new regex compiler like deflexer does
;
(defmacro tokenize (str pos-var &rest rules)
(expand-tokenize str pos-var rules))
#+:Lispworks (editor:setup-indent "tokenize" 2 2 10)
(defun expand-tokenize (str pos rules &aux (strvar (gensym)) (matchedp (gensym)))
`(let ((,strvar ,str)
,matchedp *RSTART* *RLENGTH* *REGS* *LAST-SUCCESSFUL-MATCH*)
,(expand-tokenize-rules strvar pos matchedp rules)))
(defun expand-tokenize-rules (str pos matchedp rules)
(unless (null rules)
(destructuring-bind ((rule-pat . rule-actions) . rest-rules) rules
`(progn
(multiple-value-setq (,matchedp *RSTART* *RLENGTH* *REGS*)
(regex:match-str (get-matcher-for-pattern ,rule-pat)
,str :start ,pos))
(if ,matchedp
(progn
(setq *LAST-SUCCESSFUL-MATCH* ,str)
(incf ,pos *RLENGTH*)
,@rule-actions)
,(expand-tokenize-rules str pos matchedp rest-rules))))))
; (defun tokenize-test (str &optional (pos 0))
; (let ((end (length str)))
; (loop while (< pos end)
; do (tokenize str pos
; (#/[0-9]+([.][0-9]+([Ee][0-9]+)?)/ (print `(flt ,%0)))
; (#/[0-9]+/ (print `(int ,%0)))
; (#/./ (print %0))))))
;
; > (tokenize-test "1.0 2.0E5 10 30")
; (flt "1.0")
; " "
; (flt "2.0E5")
; " "
; (int "10")
; " "
; (int "30")
; NIL
;
; >
;;;
;;; Define a lexical analyser generator function. This function takes
;;; a string and optionally the start and end positions, and returns
;;; a function of no parameters that returns the two values token and
;;; value each time it is called. When the string is exhausted, it
;;; returns (values nil nil)
;;;
;;; These lexers are compatible with the lispworks parser generator.
;;;
;;; If you need to parse a stream, then just load the stream into a
;;; string and hand it to the parser. Or do it a line-at-a-time if
;;; you need a more incremental parser.
;;;
;;; This version uses the new regex compiler to good effect. It
;;; parses out each pattern, then combines them all into one big
;;; pattern that is rigged to
;;;
(defmacro deflexer (name &rest rules)
"Create a lexical analyser. This analyser function takes a string :position,
:end, :end-token and :end-value keyword parameters, and returns a function of
no arguments that returns the next token and value each time it is called,
or (values end-token end-value) when the input string is exhausted.
By default, position = 0, end = length of str, and end-token and end-value = nil."
(let ((matchervar (intern (concatenate 'string (symbol-name name) "-MATCHER")
*package*))
(rcvar (gensym))
(matchstartvar (gensym))
(matchlenvar (gensym))
(matchregsvar (gensym))
(strvar (gensym))
(prevposvar (gensym)))
(multiple-value-bind (patterns actions)
(extract-patterns-and-actions rules)
`(progn
(defparameter ,matchervar (macroexpand-regex-expr ',(combine-patterns patterns)))
(defun ,name (,strvar &key (start 0)
(end (length ,strvar))
(end-token nil)
(end-value nil)
&aux (,prevposvar -1)
,rcvar ,matchstartvar ,matchlenvar ,matchregsvar)
(declare (string ,strvar) (fixnum start end))
(flet ((%n (n)
(let* ((rstart (regex:register-start ,matchregsvar n))
(rend (regex:register-end ,matchregsvar n)))
(if (and (numberp rstart) (numberp rend))
(subseq ,strvar rstart rend))))
(nextch ()
(when (< start end)
(prog1
(char ,strvar start)
(incf start)
)))
(ungetch (ch)
(when (and (characterp ch) (> start 0))
(decf start)
)))
(symbol-macrolet ((%0 (%n 0)) (%1 (%n 1)) (%2 (%n 2)) (%3 (%n 3))
(%4 (%n 4)) (%5 (%n 5)) (%6 (%n 6)) (%7 (%n 7))
(%8 (%n 8)) (%9 (%n 9)) (%10 (%n 10)))
(lambda ()
(loop while (< start end)
when (= start ,prevposvar)
do (error "Lexer unable to recognize a token in ~S, position ~D (~S)"
,strvar start
(subseq ,strvar start (min end (+ start 20))))
do (progn
(setq ,prevposvar start)
(multiple-value-setq (,rcvar ,matchstartvar ,matchlenvar ,matchregsvar)
(match-str ,matchervar ,strvar :start start))
(if ,rcvar
(incf start ,matchlenvar)
(error "~A lexing failure (no token recognized) in ~S @ ~D"
',name ,strvar start))
(case ,rcvar
,@(make-lexer-actions actions)
(otherwise
(error "~A lexing failure (unknown token) in ~S @ ~D, ~S ~S ~S ~S"
',name ,strvar start
,rcvar ,matchstartvar ,matchlenvar ,matchregsvar))))
finally (return (values end-token end-value)))))))))))
#+:Lispworks (editor:setup-indent "deflexer" 1 2 10)
; Pull out the patterns and actions, with rule numbers so we can keep them associated
(defun extract-patterns-and-actions (rules &aux patterns actions)
(loop for rule in rules
for rulenum from 0
for pat = (first rule)
for action = (rest rule)
do (progn
(push `(,pat ,rulenum) patterns)
(push `(,action ,rulenum) actions))
finally (return (values (nreverse patterns) (nreverse actions)))))
; Combines patterns into one big ALT, with clause extended with a new success node
; that returns the pattern number that matched.
(defun combine-patterns (pats)
(flet ((make-specialized-parsetree (patstr hooknum)
(let ((parsetree (regex:parse-str patstr)))
(when (null parsetree)
(error "Regex compile error in ~S" patstr))
(regex:make-seq-node-args
parsetree
(regex:make-success-node hooknum)))))
(make-alt-node-list
(mapcar #'make-specialized-parsetree
(mapcar #'first pats)
(mapcar #'second pats)))))
; Build the body of the case statement that performs the action corresponding to
; the matched pattern.
(defun make-lexer-actions (actions)
(mapcar #'(lambda (action)
`(,(second action) (progn ,@(first action))))
actions))
;(deflexer test-lexer
; ("[0-9]+([.][0-9]+([Ee][0-9]+)?)"
; (return (values 'flt (num %0))))
; ("[0-9]+"
; (return (values 'int (int %0))))
; ("[0-9]+X"
; (return (values 'int (int %0))))
; ("[0-9]+L"
; (return (values 'int (int %0))))
; ("while" (return 'while))
; ("wend" (return 'wend))
; ("with" (return 'with))
; ("wabbit" (return 'wabbit))
; ("for" (return 'for))
; ("in" (return 'in))
; ("loop" (return 'loop))
; ("var" (return 'var))
; ("[:alpha:][:alnum:]*"
; (return (values 'name %0)))
; ("[:space:]+")
; )
;
; > (setq *lex* (test-lexer "1.0 12 fred with wabbit 10.23e12"))
; <closure ...>
;
; > (funcall *lex*)
; FLT
; 1.0
;
; > (funcall *lex*)
; INT
; 12
;
; > (funcall *lex*)
; NAME
; "fred"
;
; > (funcall *lex*)
; WITH
;
; > (funcall *lex*)
; WABBIT
;
; > (funcall *lex*)
; FLT
; 1.0229999999999997E46
;
; > (funcall *lex*)
; NIL
; NIL
;
; >
;;;
;;; Cribbed from clawk
;;;
;;;
;;; NUM
;;;
(defgeneric num (x))
(defmethod num ((x number))
x)
(defmethod num ((x (eql nil)))
0)
(defmethod num ((x string))
(let ((val (read (make-string-input-stream x))))
(if (numberp val)
val
0)))
;;;
;;; INT
;;;
(defgeneric int (x))
(defmethod int ((x integer))
x)
(defmethod int ((x number))
(round x))
(defmethod int ((x (eql nil)))
0)
(defmethod int ((x string))
(let ((val (read (make-string-input-stream x) nil 0)))
(if (numberp val)
(round val)
0)))
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