--- /dev/null
+(in-package #:clnl-lexer)
+
+; I played around with using #'read for netlogo code, which would have been neat.
+; However, it provides too many instances where people could inject CL code
+; and I wanted to prevent that. In the end, writing my own lexer became kind of fun.
+
+(defvar *state* :initial)
+(defvar *states* :extension-literal)
+(defparameter *lexes* nil)
+
+(defun as-symbol (text) (intern (string-upcase text) :keyword))
+
+(defmacro deflex (state match &optional func)
+ (let
+ ((scanner (gensym)))
+ `(let
+ ((,scanner (when (stringp ,match) (cl-ppcre:create-scanner ,match))))
+ (pushnew
+ (list
+ (lambda (state text)
+ (and
+ (eql ,state state)
+ (or
+ (and (symbolp text) (eql text ,match))
+ (and
+ ,scanner
+ (stringp text)
+ (multiple-value-bind (start end) (cl-ppcre:scan ,scanner text)
+ (and start end (= 0 start) (/= 0 end)))))))
+ (lambda (text) (second (multiple-value-list (cl-ppcre:scan ,scanner text))))
+ ,(or func #'as-symbol))
+ *lexes*))))
+
+(defun lex (text)
+ "LEX TEXT => AST
+
+ARGUMENTS AND VALUES:
+
+ TEXT: Some NetLogo code
+ AST: An ambigious AST that can later be parsed
+
+DESCRIPTION:
+
+ LEX lexes NetLogo code.
+
+ LEX checks for some things, in as much as it can without knowing anything
+ about some of the backgrounds of NetLogo. However, it does the first pass
+ with as much as it can."
+ (if (string= "" text)
+ (let
+ ((lex (find-if (lambda (f) (funcall f *state* :eof)) *lexes* :from-end t :key #'car)))
+ (when lex (list (funcall (third lex) :eof))))
+ (let
+ ((lex (find-if (lambda (f) (funcall f *state* text)) *lexes* :from-end t :key #'car)))
+ (when (not lex) (error "Can't lex this: ~S" text))
+ (let
+ ((val (funcall (third lex) (subseq text 0 (funcall (cadr lex) text)))))
+ (if val
+ (cons val (lex (subseq text (funcall (cadr lex) text))))
+ (lex (subseq text (funcall (cadr lex) text))))))))
+
+(defun set-state (new-state)
+ (setf *state* new-state))
+
+; This part is the actual netlogo spec
+
+(defvar *string-text* "(\\\\\"|\\\\n|\\\\r|\\\\t|\\\\|[^\\r\\n\\\"])")
+(defvar *nonnewline_white_space_char* "[ \\t\\b\\012]")
+(defvar *letter* "\\w")
+(defvar *digit* "\\d")
+(defvar *identifier-char* "[\\w\\d_.?=\*!<>:#\+/%$\^'&-]")
+
+;(defvar *extension-literal-depth* 0)
+;(defstruct extension-literal text)
+
+;(deflex :initial "{{"
+; (lambda (text)
+; (set-state :extension-literal)
+; (as-symbol text)
+; ))
+
+;(deflex :extension-literal "}}"
+; (lambda (text)
+; (if (= 0 *extension-literal-depth*)
+; (progn (set-state :initial) text)
+; (progn (decf *extension-literal-depth*) (as-symbol text)))))
+
+;(deflex :extension-literal "{{"
+; (lambda (text) (incf *extension-literal-depth*) text))
+
+;(deflex :extension-literal "\n|\r" (lambda () (error "End of line reached unexpectedly")))
+;(deflex :extension-literal :eof (lambda () (error "end of file reached unexpectedly")))
+;(deflex :extension-literal ".")
+
+(deflex :initial "[,\\{\\}\\[\\]\\(\\)]" #'as-symbol)
+(deflex :initial *nonnewline_white_space_char* (constantly nil))
+(deflex :initial "\\n|\\r" (constantly nil))
+(deflex :initial ";.*[\n\r]?" (constantly nil))
+(deflex :initial (format nil "-?\\.?[0-9]~A*" *identifier-char*)
+ (lambda (text)
+ (let
+ ((num?
+ (let
+ ((*readtable* (copy-readtable nil))
+ (*read-eval* nil))
+ (read-from-string (format nil "~Ad0" text)))))
+ (if (numberp num?) num? (error "Invalid number")))))
+
+(deflex :initial (format nil "~A*" *identifier-char*) #'as-symbol)
+(deflex :initial (format nil "\"~A*\"" *string-text*)
+ ; While this shouldn't let harmful strings in,
+ ; one can't be too careful
+ (lambda (text)
+ (let
+ ((*readtable* (copy-readtable nil))
+ (*read-eval* nil))
+ (read-from-string text))))
+
+(deflex :initial (format nil "\"~A*" *string-text*)
+ (lambda (text) (declare (ignore text)) (error "Closing double quote is missing")))
+;(deflex :initial "." (lambda (text) (error "Non standard character is not allowed")))
projects / clnl / blobdiff