path: root/src/interp/parsing.lisp

;; Copyright (c) 1991-2002, The Numerical ALgorithms Group Ltd.
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; NAME:    META/LISP Parser Generator and Lexical Analysis Utilities (Parsing)
;
; PURPOSE: This package provides routines to support the Metalanguage
;          translator writing system.   Metalanguage is described
;          in META/LISP, R.D. Jenks, Tech Report, IBM T.J. Watson Research Center,
;          1969.  Familiarity with this document is assumed.
;
;          The parser generator itself is described in either the file
;          MetaBoot.lisp (hand-coded version) or the file MetaMeta.lisp (machine
;          generated from self-descriptive Meta code), both of which load themselves
;          into package Parsing.

; CONTENTS:
;
;       0. Current I/O Stream definition
;
;       1. Data structure declarations (defstructs) for parsing objects
;
;               A. Line Buffer
;               B. Stack
;               C. Token
;               D. Reduction
;
;       2. Recursive descent parsing support routines
;               A. Stacking and retrieving reductions of rules.
;               B. Applying metagrammatical elements of a production (e.g., Star).
;
;       3. Routines for handling lexical scanning
;
;               A. Manipulating the token stack and reading tokens
;               B. Error handling
;               C. Constructing parsing procedures
;               D. Managing rule sets
;
;       4. Tracing routines
;
;       5. Routines for inspecting and resetting total I/O system state
;
;       METALEX.LISP:  Meta file handling, auxiliary parsing actions and tokenizing
;
;       BOOTLEX.LISP:  Boot file handling, auxiliary parsing actions and tokenizing
;       NEWMETA.LISP:  Boot parsing


(import-module "metalex")
(in-package "BOOT")

(defun IOStreams-Show ()
  (format t "~&Input is coming from ~A, and output is going to ~A.~%"
           (or (streamp in-stream) "the keyboard")
           (or (streamp out-stream) "the screen"))
  (format t "~:[~;The current input stream is logically closed.~%~]~%" File-Closed))

(defmacro IOStreams-Set (input output) `(setq in-stream ,input out-stream ,output))

(defmacro IOStreams-Clear (&optional (in t) (out t))
  `(progn (and (streamp in-stream) (close in-stream))
          (and (streamp out-stream) (close out-stream))
          (setq File-Closed nil)
          (IOStreams-Set ,in ,out)))

; 2B. Routines for applying certain metagrammatical elements
;     of a production (e.g., Star).

; Must means that if it is not present in the token stream, it is a syntax error.

; FUNCTIONS DEFINED IN THIS SECTION:
;
;       Star, Bang, Must, Optional, Action

(defmacro Star (lab prod)

"Succeeds if there are one or more of PROD, stacking as one unit
the sub-reductions of PROD and labelling them with LAB.
E.G., (Star IDs (parse-id)) with A B C will stack (3 IDs (A B C)),
where (parse-id) would stack (1 ID (A)) when applied once."

  `(prog ((oldstacksize (stack-size reduce-stack)))
         (if (not ,prod) ;(progn (format t "~&Star failed for ~A.~%" ',lab) (return nil)))
             (return nil))
    loop (if (not ,prod)
             (let* ((newstacksize (stack-size reduce-stack))
                    (number-of-new-reductions (- newstacksize oldstacksize)))
;              (format t "~&Starring ~A with ~D new reductions.~%"
;                      ',lab number-of-new-reductions)
               (if (> number-of-new-reductions 0)
                   (return (do ((i 0 (1+ i)) (accum nil))
                               ((= i number-of-new-reductions)
                                (Push-Reduction ',lab accum)
;                               (format t "~&Star accumulated ~D reductions.~%"
;                                       (length accum))
                                (return t))
                             (push (pop-stack-1) accum)))
                   (return t)))
             (go loop))))

(defmacro Bang (lab prod)

"If the execution of prod does not result in an increase in the size of
the stack, then stack a NIL. Return the value of prod."

  `(progn (setf (stack-updated reduce-stack) nil)
;         (format t "~&Banging ~A~:[~; and I think the stack is updated!~].~%" ',lab
;                 (stack-updated reduce-stack))
          (let* ((prodvalue ,prod)
                 (updated (stack-updated reduce-stack)))
;           (format t "~&Bang thinks that ~A ~:[didn't do anything~;did something~].~&"
;                   ',lab prodvalue)
            (if updated
                (progn ; (format t "~&Banged ~A and I think the stack is updated!~%" ',lab)
                       prodvalue)
                (progn (push-reduction ',lab nil)
                       ; (format t "~&Banged ~A.~%" ',lab)
                       prodvalue)))))

(defmacro must (dothis &optional (this-is nil) (in-rule nil))
  `(or ,dothis (meta-syntax-error ,this-is ,in-rule)))

; Optional means that if it is present in the token stream, that is a good thing,
; otherwise don't worry (like [ foo ] in BNF notation).

(defun Optional (dothis) (or dothis t))

; Action is something we do as a consequence of successful parsing; it is
; inserted at the end of the conjunction of requirements for a successful
; parse, and so should return T.

(defun action (dothis) (or dothis t))

; 3A.  Manipulating the token stack and reading tokens

; This section is broken up into 3 levels:
;
;       (0) String grabbing:    Match String, Match Advance String
;       (1) Token handling:     Current Token, Next Token, Advance Token
;       (2) Character handling: Current Char, Next Char, Advance Char
;       (3) Line handling:      Next Line, Print Next Line
;       (X) Random Stuff

; A good test for lexing is:

(defmacro test-lexing ()
  '(with-open-file (in-stream "lisp>meta.meta" :direction :input)
    (with-open-file (out-stream "lisp>foo.pars" :direction :output :if-exists :supersede)
      (loop (let ((z (advance-token)))
              (if z (Token-Print z out-stream) (return nil)))))))

; 3A (0). String grabbing

; String grabbing is the art of matching initial segments of the current
; line, and removing them from the line before the get tokenized if they
; match (or removing the corresponding current tokens).

; FUNCTIONS DEFINED IN THIS SECTION:
;
;       Match-String, Match-Advance-String

(defun Match-String (x)
  "Returns length of X if X matches initial segment of inputstream."
  (unget-tokens)                        ; So we don't get out of synch with token stream
  (skip-blanks)
  (if (and (not (Line-Past-End-P Current-Line)) (Current-Char) )
      (initial-substring-p x
           (subseq (Line-Buffer Current-Line) (Line-Current-Index Current-Line)))))

(defun Match-Advance-String (x)
  "Same as MATCH-STRING except if successful, advance inputstream past X."
  (let ((y (if (>= (length (string x))
                   (length (string (quote-if-string (current-token)))))
               (Match-String x)
               nil))) ; must match at least the current token
    (if y (progn (incf (Line-Current-Index Current-Line) y)
                 (if (not (Line-Past-End-P Current-Line))
                     (setf (Line-Current-Char Current-Line)
                           (elt (Line-Buffer Current-Line)
                                (Line-Current-Index Current-Line)))
                     (setf (Line-Current-Char Current-Line) #\Space))
                 (setq prior-token
                       (make-token :Symbol (intern (string x))
                                   :Type 'identifier
                                   :nonBlank nonblank))
                 t))))

(defun initial-substring-p (part whole)
  "Returns length of part if part matches initial segment of whole."
  (let ((x (string-not-greaterp part whole)))
    (and x (= x (length part)) x)))



; 3A 3. Line Handling.

; PARAMETERS DEFINED IN THIS SECTION:
;
;       Echo-Meta

; 3B. Error handling

(defparameter errcol nil)
(defparameter line nil)

(defun conversation (x y)
  (prog (u)
     a  (reduce-stack-clear)
        (setq u (namederrset 'spad_reader (conversation1 x y) ))
        (cond (*eof* (return nil))
              ((atom u) (go a))
              ((return (car u))))))

(defparameter ulcasefg nil              "")

(defun conversation1 (firstfun procfun)
  (prog nil
     top(cond ((not (Current-Char)) (return nil))
              ((and (current-token) (next-token)) (go top))
              ((compfin) (return 't))
              ((and (funcall firstfun)
                    (or (funcall procfun (pop-stack-1))))
               (go top))
              ((compfin) (return 't)) )
        (meta-syntax-error)
        (go top)))

(defun termchr ()  "Is CHR a terminating character?"
  (position (current-char) " *,;<>()[]/\\"))

(defun compfin () (or (match-string ")fin") (match-string ".FIN")))

; 3 C. Constructing parsing procedures

; FUNCTIONS DEFINED IN THIS SECTION:
;
;       Make-Parse-Function, GetGenSym

(MAKEPROP 'PROGN 'NARY T)       ; Setting for Make-Parse-Function

(defun make-parse-function (l op)
   (if (flagp op 'nary) (setq l (make-parse-func-flatten-1 l op nil)))
   (make-parse-function1 l op))

(defun make-parse-func-flatten (x op)
  (cond ((atom x) x)
        ((eq (car x) op) (cons op (make-parse-func-flatten-1 (cdr x) op nil)))
        (t (cons (make-parse-func-flatten (car x) op) (make-parse-func-flatten (cdr x) op)))))

(defun make-parse-func-flatten-1 (l op r)
  (let (x)
    (if (null l)
        r
        (make-parse-func-flatten-1
            (cdr l) op
            (append r (if (eqcar (setq x (make-parse-func-flatten (car l) op)) op)
                          (cdr x)
                          (list x)))))))

(defun make-parse-function1 (l op)
  (let (x)
    (case op
      (plus (cond ((eq 0 (setq x (length (setq l (s- l '(0 (zero))))))) 0)
                  ((eq 1 x) (car l))
                  (t `(+ . ,l))))
      (times (cond ((s* l '(0 (zero))) 0)
                   ((eq 0 (setq x (length (setq l (s- l '(1 (one))))))) 1)
                   ((eq 1 x) (car l))
                   (t `(times . ,l)) ))
      (quotient (cond ((> (length l) 2) (fail))
                      ((eq 0 (car l)) 0)
                      ((eq (cadr l) 1) (car l))
                      (t `(quotient . ,l)) ))
      (minus (cond ((cdr l) (fail))
                   ((numberp (setq x (car l))) (minus x))
                   ((eqcar x 'minus) (cadr x))
                   (t `(minus . ,l))  ))
      (- (cond ((> (length l) 2) (fail))
                        ((equal (car l) (cadr l)) '(zero))
                        ((member (car l) '(0 (zero))) (make-parse-function (cdr l) 'minus))
                        ((member (cadr l) '(0 (zero))) (car l))
                        ((eqcar (cadr l) 'minus)
                         (make-parse-function (list (car l) (cadadr l)) 'plus))
                        (t `(- . ,l)) ))
      (expt (cond ((> (length l) 2) (fail))
                  ((eq 0 (cadr l)) 1)
                  ((eq 1 (cadr l)) (car l))
                  ((member (car l) '(0 1 (zero) (one))) (car l))
                  (t `(expt . ,l)) ))
      (or (cond ((member 't l) ''t)
                ((eq 0 (setq x (length (setq l (delete nil l))))) nil)
                ((eq 1 x) (car l))
                (t `(or . ,l)) ))
      (|or| (cond ((member 't l) 't)
                  ((eq 0 (setq x (length (setq l (delete nil l))))) nil)
                  ((eq 1 x) (car l))
                  (t `(|or| . ,l)) ))
      (null (cond ((cdr l) (fail))
                  ((eqcar (car l) 'null) (cadar l))
                  ((eq (car l) 't) nil)
                  ((null (car l)) ''t)
                  (t `(null . ,l))))
      (|and| (cond ((eq 0 (setq x (length (setq l (delete 't (delete 'true l)))))) 't)
                   ((eq 1 x) (car l))
                   (t `(|and| . ,l)) ))
      (and (cond ((eq 0 (setq x (length (setq l (delete 't (delete 'true l)))))) ''t)
                 ((eq 1 x) (car l))
                 (t `(and . ,l)) ))
      (progn (cond ((and (not (atom l)) (null (last l)))
                    (cond ((cdr l) `(progn . ,l))
                          (t (car l))))
                   ((null (setq l (delete nil l))) nil)
                   ((cdr l) `(progn . ,l))
                   (t (car l)) ))
      (seq (cond ((eqcar (car l) 'exit) (cadar l))
                 ((cdr l) `(seq . ,l))
                 (t (car l))   ))
      (list (cond ((null l) nil) (t `(list . ,l))))
      (cons (cond ((cdr l) `(cons . ,l)) (t (car l)) ))
      (t (cons op l) ))))

(defparameter /genvarlst nil    "??")

(defun transpgvar (metapgvar) (remove-duplicates metapgvar))

(defparameter /gensymlist nil   "List of rule local variables generated by getgensym.")

(defun getgensym (n)
  "Used to create unique numerically indexed local variables for the use of rules."
  (loop
     (let ((m (length /gensymlist)))
       (if (< m n)
           (setq /gensymlist (nconc /gensymlist `(,(intern (format nil "G~D" (1+ m))))))
           (return (nth (1- n) /gensymlist))))))

; 3 D.  Managing rule sets

(defparameter bac nil                   "")
(defparameter keyfn nil                 "")
(defparameter /metaoption               "")
(defparameter tline nil                 "")
(defparameter rs nil                    "")

(defun getrulefunlists  (rootfun rs)
  (let* ((metapfx (or (get rootfun 'metapfx) ""))
         (mainfun (internl metapfx (pname rootfun)))
         (mainfunstr (pname mainfun))
         (flnam (internl mainfunstr "FUN"))
         (pfx-funlist (union (cons mainfun
                                   (if (atom (eval flnam)) nil (eval flnam)))
                             (mapcar #'(lambda (x) (internl metapfx (pname x)))
                                     (assocleft rs))))
         n unpfx-funlist)
    (set flnam pfx-funlist)
    (if (not (lessp (setq n (length metapfx)) 0))
        (setq unpfx-funlist
              (mapcar #'(lambda (x) 
			  (intern (subseq 
				   (symbol-name (copy-symbol (pname x))) n)))
                       pfx-funlist)))
    (if unpfx-funlist (list pfx-funlist unpfx-funlist))))

;  4. Tracing routines

(defparameter debugmode 'yes "Can be either YES or NO")

(defun reduction-print (y rule)
  (format t "~&")
  (cond ((eq y t) (|sayBrightly| `(|%b| ,rule |%d| " reduced")))
        (y (|sayBrightlyNT| `(|%b| ,rule |%d|))
           (format t " reduced ~A~%" y)))
  y)

#+Symbolics
(defmacro rtrace (&rest rules)
  `(compiler-let () .
        ,(mapcar #'(lambda (x)
                    (let ((rule (intern (strconc "PARSE-" x))))
                      `(zl:advise ,rule :around nil nil
                               (reduction-print :do-it ',rule))))
                rules)))

#+Symbolics
(defmacro runtrace () `(zl:unadvise))

(defmacro tracemeta (&rest l) `(trmeta ',l))

(defparameter /depth 0 "Used in Debug.lisp.")

(defun trmeta (l) (setq /depth 0) (mapc #'trmeta1 l))

(defun trmeta1 (x)
  (let (y)
  (if (not (fboundp  x))
      (if (fboundp (setq y (internl $lastprefix (pname x))))
          (moan (format nil "********* ~S RENAMED AS ~S" x (setq x y)))
          (croak (format nil  "********* ~S MUST BE GIVEN PREFIX" x))))
  (/embed-1 x
   (sublislis
     (list (pname x) x (gensym))
     '(nam* fun* argl*)
     '(lambda (&rest argl*)
       (prog (v tok)
         (terpri)
         (trblanks (* 2 /depth))          (setq /depth (+ 1 /depth))
         (princ (stringimage /depth))  (princ "<")
         (princ nam*)              (trargprint argl*)   (princ "/")
         (princ "chr= ")           (prin1 (Current-Char))
         (princ "/tok= ")          (prin1 (setq tok (current-symbol)))
         (princ "/col= ")          (prin1 (line-current-index current-line))
 ;;      (princ "/icol= ")         (prin1 initcolumn)
         (cond ( (not nonblank) (go a1)))     (princ "/nblnk= T")
     a1  ;;(cond (ok (go b1)))               (princ "/ok= NIL")
     b1  ;;(cond ( (not stackx) (go c1)))   (princ "/stackx= ")
         ;;(prin1 stackx)
     c1  (cond ( (not (identp tok)) (go d1)))
         (princ "/isid= ")
        ;; (princ (cond (isid "T") (t "NIL")))
     d1  (princ "/stack= ")            (prin1 (stack-store reduce-stack))
         (setq v (apply fun* argl*))           (setq /depth (- /depth 1))
         (terpri)
         (trblanks (* 2 /depth))          (princ (stringimage (\1+ /depth)))
         (princ ">")                       (princ nam*)
         (princ "/chr= ")                  (prin1 (Current-Char))
         (princ "/tok= ")                  (prin1 (setq tok (current-symbol)))
         (princ "/col= ")            (prin1 (line-current-index current-line))
         (if (not nonblank) (go a2))          (princ "/nblnk= ")
         (princ (if nonblank "T" "NIL"))
     a2  ;;(if ok (go b2))                   (princ "/ok= ")          (prin1 ok)
     b2  ;;(if (not stackx) (go c2))        (princ "/stackx1= ")     (prin1 stackx)
     c2  (if (not (identp tok)) (go d2))
         (princ "/isid= ")
        ;; (princ (if isid "T" "NIL"))
     d2  (princ "/stack= ")            (prin1 (stack-store reduce-stack))
         (princ "/value= ")         (prin1 v)
         (return v)))))))

(defun /embed-1 (x y)
   (princ (strconc (pname x) " embedded"))
   (terpri)
   (/embed-q x y))

(defvar /embednames)

(defun /embed-q (x y)
   (setq /embednames (cons x /embednames))
   (embed x
          (cond ((eqcar y 'lambda) y)
                ((eqcar y 'before)
                 `(lambda ,(cadr y)
                    (prog2 ,(caddr y) ,(cons 'funcall (cons x (cadr y))))))
                ((eqcar y 'after)
                 `(lambda ,(cadr y)
                    (prog1 ,(cons 'funcall (cons x (cadr y))) ,(caddr y))))))
   (/embedreply))

(defun /embedreply ()
  (if (atom (embedded)) '(|none| |embedded|)
      (append (embedded) (list '|embedded|))))

(defparameter mdeftrace nil             "")

(defun /mdef (x)
  (let (u)
    (cond  ((atom x) x)
           ((or (null (atom (car x))) (not (mbpip (car x))))
            (mapcar #'/mdef x))
           ((equal x (setq u (mdef (car x) x))) x)
           (mdeftrace (print x) (princ " --> ") (print u) (/mdef u))
           ((/mdef u)))))

(defun trargprint (l) (mapc #'(lambda (x) (princ " / ") (prin1 x)) l))

(defun trblanks (n) (do ((i 1 (1+ i))) ((> i n)) (princ " ")))

;       5. Routines for inspecting and resetting total I/O system state
;
; The package largely assumes that:
;
;       A. One I/O stream pair is in effect at any moment.
;       B. There is a Current Line
;       C. There is a Current Token and a Next Token
;       D. There is a Reduction Stack
;
; This state may be examined and reset with the procedures IOSTAT and IOCLEAR.

(defun IOStat ()
  "Tell me what the current state of the parsing world is."
  ;(IOStreams-show)
  (current-line-show)
  (if (or $BOOT $SPAD) (next-lines-show))
  (token-stack-show)
  ;(reduce-stack-show)
  nil)

(defun IOClear (&optional (in t) (out t))
  ;(IOStreams-clear in out)
  (input-clear)
  (current-line-clear)
  (token-stack-clear)
  (reduce-stack-clear)
  (if (or $BOOT $SPAD) (next-lines-clear))
  nil)

;; auxiliary functions needed by the parser

(defun char-eq (x y) (char= (character x) (character y)))

(defun char-ne (x y) (char/= (character x) (character y)))

(Defun FLOATEXPID (X &aux S)
  (if (AND (IDENTP X) (char= (char-upcase (ELT (SETQ S (PNAME X)) 0)) #\E)
           (> (LENGTH S) 1)
           (SPADREDUCE AND 0 (COLLECT (STEP I 1 1 (MAXINDEX S))
                                      (DIGITP (ELT S I)))))
       (READ-FROM-STRING S t nil :start 1)
    NIL))

(defun |getToken| (x) (if (EQCAR x '|elt|) (third x) x))

(defun |dollarTran| (dom rand)
       (let ((eltWord (if |$InteractiveMode| '|$elt| '|elt|)))
         (if (and (not (atom rand)) (cdr rand))
             (cons (list eltWord dom (car rand)) (cdr rand))
             (list eltWord dom rand))))