/usr/share/maxima/5.32.1/src/trans3.lisp is in maxima-src 5.32.1-1.
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;;; The data in this file contains enhancments. ;;;;;
;;; ;;;;;
;;; Copyright (c) 1984,1987 by William Schelter,University of Texas ;;;;;
;;; All rights reserved ;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; (c) Copyright 1980 Massachusetts Institute of Technology ;;;
;;; Maintained by GJC ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(in-package :maxima)
(macsyma-module trans3)
;;; The translation of macsyma LAMBDA into lexicaly scoped closures.
;;; Two cases [1] the downward transmission of variable binding environment,
;;; e.g. MAP(LAMBDA([U],F(U,X)),EXP)
;;; [2] downward and upward, requiring a full closure, e.g.
;;; MAP(LAMBDA([U],SUM:SUM+U),EXP);
;;; LAMBDA([U],F(U,X)) =>
;;; (DOWN-CLOSE (LAMBDA (U) (F U X)) (X))
;;; TBIND, TBOUNDP, and TUNBIND and TUNBINDS hack lexical scoping.
;;; A function to determine free vars from a lisp expression.
;;; It returns a <var-set> which is a list of pairs
;;; (<var> . <side-effectp>)
;;; N.B. This code does a veritable storm of consing, it need not
;;; do any if it used the lambda-bound plist scheme of GJC;UTRANS >
;;; a compiler is allowed to cons though, isn't it?
(defun free-lisp-vars (exp &aux prop)
(cond ((atom exp)
(cond ((or (null exp)(eq t exp)) nil)
((symbolp exp) `((,exp . nil)))
(t nil)))
((atom (car exp))
(cond ((setq prop (get (car exp) 'free-lisp-vars))
(funcall prop exp))
((setq prop (get (car exp) 'free-lisp-vars-macro))
(free-lisp-vars (funcall prop exp)))
((setq prop (get (car exp) 'macro))
(free-lisp-vars (funcall prop exp)))
((getl (car exp) '(fsubr fexpr))
(warn-fexpr (car exp)
"environment may fail to be correct.")
(free-lisp-vars-of-argl (cdr exp)))
(t
(free-lisp-vars-of-argl (cdr exp)))))
((eq (caar exp) 'lambda)
(sum-var-sets (free-lisp-vars (car exp))
(free-lisp-vars-of-argl (cdr exp))))
(t
(barfo "Bad lisp expression generated."))))
(defun free-lisp-vars-of-argl (argl)
(union-var-set (mapcar #'free-lisp-vars argl)))
;;; (REDUCE-VAR-SET '((A . NIL) NIL (B . T) (B . NIL))) => ((A . NIL) (B . T))
;;; mult-set reduction.
(defun reduce-var-set&op (var-set op)
(do ((var-set var-set (cdr var-set))
(reduced-var-set nil)
(var1)
(var2))
((null var-set) reduced-var-set)
(setq var1 (car var-set))
(cond ((null var1))
((setq var2 (assoc (car var1) reduced-var-set :test #'eq))
(rplacd var2 (funcall op (cdr var1) (cdr var2))))
(t
(push var1 reduced-var-set)))))
(defun reduce-var-set (var-set)
(reduce-var-set&op var-set #'(lambda (p1 p2)(or p1 p2))))
;;; S1 - S2. S1 reduced, minus any vars that are in S2.
(defun difference-var-sets (s1 s2)
(setq s1 (reduce-var-set s1))
(do ((s nil))
((null s1) s)
(cond ((assoc (caar s1) s2 :test #'eq)) ;;; is the first elem of S1 a member of S2?
(t
(push (car s1) s))) ;;; yes. shove it in.
(pop s1)))
;;; N.B. union of var sets is defined classicaly ala G.F.
(defun union-var-set (set-of-var-sets)
(reduce-var-set (apply #'append set-of-var-sets)))
;;; SUM-VAR-SETS is the usual convention.
(defun sum-var-sets (&rest l)
(reduce-var-set (apply #'append l))) ; consing up a storm aren't we?
(defun make-var-set (vars)
(loop for v in vars collect (ncons v)))
;;; (LAMBDA <BVL> . <BODY>)
(defun-prop (lambda free-lisp-vars) (form)
(difference-var-sets (free-lisp-vars-of-argl (cddr form))
(cond ((null (cadr form))
nil)
((atom (cadr form))
(make-var-set (list (cadr form))))
(t
(make-var-set (cadr form))))))
;;; (PROG <BVL> . <BODY>)
(defun-prop (prog free-lisp-vars) (form)
(difference-var-sets (union-var-set
(mapcar #'(lambda (u)
(cond ((atom u) nil) ;; go tag.
(t
(free-lisp-vars u))))
(cddr form)))
(make-var-set (cadr form))))
;;; no computed gos please.
(defun-prop (go free-lisp-vars) (ignor)ignor nil)
;;; (DO ((<V> <V> <V>) ...) ((<in-scope>) ..) ...)
(defun-prop (do free-lisp-vars) (form)
(difference-var-sets
(sum-var-sets (free-lisp-vars-of-argl (cdddr form))
(free-lisp-vars-of-argl (caddr form))
(union-var-set (mapcar #'(lambda (do-iter)
(free-lisp-vars-of-argl
(cdr do-iter)))
(cadr form))))
(make-var-set (mapcar #'car (cadr form)))))
;;; (COND (<I> ..) (<J> ..) ...)
(defun-prop (cond free-lisp-vars) (form)
(union-var-set (mapcar #'free-lisp-vars-of-argl (cdr form))))
(defun-prop (quote free-lisp-vars) (ignor)ignor nil)
(defun-prop (function free-lisp-vars) (ignor)ignor nil)
;;; (SETQ ... ODD AND EVENS...)
(defun-prop (setq free-lisp-vars) (form)
(do ((free-vars nil (sum-var-sets `((,(car form) . t))
(free-lisp-vars (cadr form))
free-vars))
(form (cdr form) (cddr form)))
((null form) free-vars)))
;;; uhm. LAMBDA, PROG, GO, DO, COND, QUOTE, SETQ.
(defun-prop (and free-lisp-vars)(form)(free-lisp-vars-of-argl (cdr form)))
(defun-prop (or free-lisp-vars)(form)(free-lisp-vars-of-argl (cdr form)))
(defun-prop (comment free-lisp-vars) (ignor)ignor nil)
(defun-prop (declare free-lisp-vars) (ignor) ignor nil)
;;; these next forms are generated by TRANSLATE.
(defprop $piece t sort-of-lexical)
(defun-prop (trd-msymeval free-lisp-vars) (form)
(if (get (cadr form) 'sort-of-lexical)
;; acts like a lexical variable because of the $SUBSTPART translator.
(list (list (cadr form)))
()))
(defun-prop (mfunction-call free-lisp-vars) (form)
;; it is not strictly known if the name of the function being called
;; is a variable or not. lets say its not.
(free-lisp-vars-of-argl (cddr form)))
;;; (FUNGEN&ENV-FOR-MEVAL () () EXP)
(defun-prop (fungen&env-for-meval free-lisp-vars) (form)
(free-lisp-vars (car (cdddr form))))
;;; the various augmented lambda forms.
(defun free-lisp-vars-m-tlambda (form)
(difference-var-sets (free-lisp-vars-of-argl (cddr form))
(free-lisp-vars-of-argl (cadr form))))
(mapc #'(lambda (u) (putprop u 'free-lisp-vars-m-tlambda 'free-lisp-vars))
'(m-tlambda m-tlambda&))
(defun free-lisp-vars-m-tlambda&env (form)
(difference-var-sets (free-lisp-vars-of-argl (cddr form))
(free-lisp-vars-of-argl (car (cadr form)))))
(defprop m-tlambda&env free-lisp-vars-m-tlambda&env free-lisp-vars)
(defprop m-tlambda&env& free-lisp-vars-m-tlambda&env free-lisp-vars)
;;; Other entry points:
(defun tbound-free-vars (free-varl)
;; Takes a FREE-VAR list and returns a list of two lists.
;; the tbound free vars and the tbound free vars that are
;; side effected also.
(do ((free nil)
(free&s nil))
((null free-varl) (list free free&s))
(let ((v (pop free-varl)))
(cond ((and (tboundp (car v))
(not (get (car v) 'special)))
(push (car v) free)
(cond ((cdr v)
(push (car v) free&s))))))))
(defun side-effect-free-check (varl form)
(cond ((null varl) t)
(t
(tr-format (intl:gettext "error: unsupported side effects on ~:M in expression ~M~%") `((mlist) ,@varl) form)
nil)))
;;; O.K. here is the translate property for LAMBDA.
;;; given catch and throw we don't know where a funarg lambda
;;; may end up.
;;; Cases:
;;; I. No side effects on free variables.
;;; A. one funarg only, not reconsed. e.g.
;;; F(N,L):=MAP(LAMBDA([U],Q(N,U)),L)$
;;; (PROGN (SET-ENV <*LINK*> N)
;;; (FUNCTION (LAMBDA (U) (LET ((N (GET-ENV *LINK*))) (f* U N)))))
;;; B. need new instance of the environment each time,
;;; F(N):=LAMBDA([U],N*U);
;;; `(LAMBDA (U) (gen-func U 'N)) without extend loaded.
;;; II. side effects.
;;; A. Those since effects need to be propogated to the environment
;;; where the LAMBDA was made. This is difficult to do in the
;;; present translator. e.g.
;;; F(L):=BLOCK([SUM:0],FULLMAP(LAMBDA([U],SUM:SUM+U),L),SUM);
;;; every function which guarantees the order of argument evalation
;;; (MPROG and MPROGN), must translate and expression and get information
;;; about environment propagation.
;;; (PROGN (FULLMAP (PROGN (SET-ENV) '(LAMBDA ...)) L)
;;; (GET-ENV)), uhm. this is pretty tricky anyway.
;;; B. side effects only have to be maintained inside the LAMBDA.
;;; this is easier, and if you have it, you really don't need II.A.
;;; since you can always ask the LAMBDA for its environment by
;;; calling it on the proper message {If the LAMBDA is written that way}.
;;; ((LAMBDA) ((MLIST) X Y ((MLIST Z))) . <BODY>)
;;; must also handle the &REST arguments. N.B. MAPPLY correctly handles
;;; the application of a lisp lambda form.
;;; Some forms know that the lambda is not going to
;;; be an upward funarg, that it is not possible (wanted)
;;; have two different lambda's generated from the same
;;; place. e.g. INTERPOLATE(SIN(X^2)=A,X,0,N) (implied lambda
;;; which is contructed by the translation property for
;;; interpolate. MAP(LAMBDA([U],...),L) is another example)
;;; these forms will be called I-LAMBDA's, and will be generated
;;; from LAMBDA's by the functions that want to. All this
;;; is meaningless in the present macsyma evaluator of course, since
;;; it uses dynamic binding and just hopes for the best.
(def%tr lambda (form)
(gen-tr-lambda form))
;;; we keep a pointer to the original FORM so that we can
;;; generate messages with it if need be.
(defun gen-tr-lambda (form &aux arg-info mode frees t-form)
(setq arg-info (mapcar #'(lambda (v)
(cond ((atom v) nil)
((and (eq (caar v) 'mlist)
(atom (cadr v)))
t)
(t '*bad*)))
(cdr (cadr form))))
(cond ((or (member '*bad* arg-info :test #'eq)
(and (member t arg-info :test #'eq)
(cdr (member t arg-info :test #'eq)))) ;;; the &REST is not the last one.
(tr-format (intl:gettext "error: unsupported argument list ~:M in lambda expression.~%") (cadr form))
(setq tr-abort t)
nil)
(t
(setq arg-info (member t arg-info :test #'eq) ;; &RESTP
t-form
(tr-lambda `((lambda)
((mlist) ,@(mapcar #'(lambda (v)
(cond ((atom v) v)
(t (cadr v))))
(cdr (cadr form))))
,@(cddr form)))
mode (car t-form) ; not much to do with the mode now,
t-form (cdr t-form) ; could be use by a global optimizer.
frees (tbound-free-vars (free-lisp-vars t-form)))))
; with this info we now dispatch to the various macros forms.
; (cadr t-form) is a lambda list. (cddr t-form) is a progn body.
(cond ((null (car frees)) ; woopie.
(cond ((null arg-info)
`($any . (m-tlambda ,@(cdr t-form))))
(t
`($any . (m-tlambda& ,@(cdr t-form))))))
((null (cadr frees))
`($any . (,(cond ((null arg-info) 'm-tlambda&env)
(t 'm-tlambda&env&))
(,(cadr t-form) ,(car frees))
,@(cddr t-form))))
(t
(warn-meval form)
(side-effect-free-check (cadr frees) form)
`($any . (meval ',form)))))
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