[bpt/guile.git] / module / ice-9 / eval.scm

;;; -*- mode: scheme; coding: utf-8; -*-

;;;; Copyright (C) 2009, 2010, 2012 Free Software Foundation, Inc.
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;; 
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;;; Lesser General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
;;;;

\f

;;; Commentary:

;;; Scheme eval, written in Scheme.
;;;
;;; Expressions are first expanded, by the syntax expander (i.e.
;;; psyntax), then memoized into internal forms. The evaluator itself
;;; only operates on the internal forms ("memoized expressions").
;;;
;;; Environments are represented as linked lists of the form (VAL ... .
;;; MOD). If MOD is #f, it means the environment was captured before
;;; modules were booted. If MOD is the literal value '(), we are
;;; evaluating at the top level, and so should track changes to the
;;; current module.
;;;
;;; Evaluate this in Emacs to make code indentation work right:
;;;
;;;    (put 'memoized-expression-case 'scheme-indent-function 1)
;;;

;;; Code:

\f

(eval-when (compile)
  (define-syntax capture-env
    (syntax-rules ()
      ((_ (exp ...))
       (let ((env (exp ...)))
         (capture-env env)))
      ((_ env)
       (if (null? env)
           (current-module)
           (if (not env)
               ;; the and current-module checks that modules are booted,
               ;; and thus the-root-module is defined
               (and (current-module) the-root-module)
               env)))))

  ;; Fast case for procedures with fixed arities.
  (define-syntax make-fixed-closure
    (lambda (x)
      (define *max-static-argument-count* 8)
      (define (make-formals n)
        (map (lambda (i)
               (datum->syntax
                x
                (string->symbol
                 (string (integer->char (+ (char->integer #\a) i))))))
             (iota n)))
      (syntax-case x ()
        ((_ eval nreq body env) (not (identifier? #'env))
         #'(let ((e env))
             (make-fixed-closure eval nreq body e)))
        ((_ eval nreq body env)
         #`(case nreq
             #,@(map (lambda (nreq)
                       (let ((formals (make-formals nreq)))
                         #`((#,nreq)
                            (lambda (#,@formals)
                              (eval body
                                    (cons* #,@(reverse formals) env))))))
                     (iota *max-static-argument-count*))
             (else
              #,(let ((formals (make-formals *max-static-argument-count*)))
                  #`(lambda (#,@formals . more)
                      (let lp ((new-env (cons* #,@(reverse formals) env))
                               (nreq (- nreq #,*max-static-argument-count*))
                               (args more))
                        (if (zero? nreq)
                            (eval body
                                  (if (null? args)
                                      new-env
                                      (scm-error 'wrong-number-of-args
                                                 "eval" "Wrong number of arguments"
                                                 '() #f)))
                            (if (null? args)
                                (scm-error 'wrong-number-of-args
                                           "eval" "Wrong number of arguments"
                                           '() #f)
                                (lp (cons (car args) new-env)
                                    (1- nreq)
                                    (cdr args)))))))))))))

  (define-syntax call
    (lambda (x)
      (define *max-static-call-count* 4)
      (syntax-case x ()
        ((_ eval proc nargs args env) (identifier? #'env)
         #`(case nargs
             #,@(map (lambda (nargs)
                       #`((#,nargs)
                          (proc
                           #,@(map
                               (lambda (n)
                                 (let lp ((n n) (args #'args))
                                   (if (zero? n)
                                       #`(eval (car #,args) env)
                                       (lp (1- n) #`(cdr #,args)))))
                               (iota nargs)))))
                     (iota *max-static-call-count*))
             (else
              (apply proc
                     #,@(map
                         (lambda (n)
                           (let lp ((n n) (args #'args))
                             (if (zero? n)
                                 #`(eval (car #,args) env)
                                 (lp (1- n) #`(cdr #,args)))))
                         (iota *max-static-call-count*))
                     (let lp ((exps #,(let lp ((n *max-static-call-count*)
                                               (args #'args))
                                        (if (zero? n)
                                            args
                                            (lp (1- n) #`(cdr #,args)))))
                              (args '()))
                       (if (null? exps)
                           (reverse args)
                           (lp (cdr exps)
                               (cons (eval (car exps) env) args)))))))))))

  ;; This macro could be more straightforward if the compiler had better
  ;; copy propagation. As it is we do some copy propagation by hand.
  (define-syntax mx-bind
    (lambda (x)
      (syntax-case x ()
        ((_ data () body)
         #'body)
        ((_ data (a . b) body) (and (identifier? #'a) (identifier? #'b))
         #'(let ((a (car data))
                 (b (cdr data)))
             body))
        ((_ data (a . b) body) (identifier? #'a)
         #'(let ((a (car data))
                 (xb (cdr data)))
             (mx-bind xb b body)))
        ((_ data (a . b) body) 
         #'(let ((xa (car data))
                 (xb (cdr data)))
             (mx-bind xa a (mx-bind xb b body))))
        ((_ data v body) (identifier? #'v)
         #'(let ((v data))
             body)))))
  
  ;; The resulting nested if statements will be an O(n) dispatch. Once
  ;; we compile `case' effectively, this situation will improve.
  (define-syntax mx-match
    (lambda (x)
      (syntax-case x (quote)
        ((_ mx data tag)
         #'(error "what" mx))
        ((_ mx data tag (('type pat) body) c* ...)
         #`(if (eqv? tag #,(or (memoized-typecode (syntax->datum #'type))
                               (error "not a typecode" #'type)))
               (mx-bind data pat body)
               (mx-match mx data tag c* ...))))))

  (define-syntax memoized-expression-case
    (lambda (x)
      (syntax-case x ()
        ((_ mx c ...)
         #'(let ((tag (memoized-expression-typecode mx))
                 (data (memoized-expression-data mx)))
             (mx-match mx data tag c ...)))))))


;;;
;;; On 18 Feb 2010, I did a profile of how often the various memoized expression
;;; types occur when getting to a prompt on a fresh build. Here are the numbers
;;; I got:
;;;
;;;      lexical-ref: 32933054
;;;             call: 20281547
;;;     toplevel-ref: 13228724
;;;               if: 9156156
;;;            quote: 6610137
;;;              let: 2619707
;;;           lambda: 1010921
;;;            begin: 948945
;;;      lexical-set: 509862
;;; call-with-values: 139668
;;;            apply: 49402
;;;       module-ref: 14468
;;;           define: 1259
;;;     toplevel-set: 328
;;;          dynwind: 162
;;;      with-fluids: 0
;;;          call/cc: 0
;;;       module-set: 0
;;;
;;; So until we compile `case' into a computed goto, we'll order the clauses in
;;; `eval' in this order, to put the most frequent cases first.
;;;

(define primitive-eval
  (let ()
    ;; We pre-generate procedures with fixed arities, up to some number of
    ;; arguments; see make-fixed-closure above.

    ;; A unique marker for unbound keywords.
    (define unbound-arg (list 'unbound-arg))

    ;; Procedures with rest, optional, or keyword arguments, potentially with
    ;; multiple arities, as with case-lambda.
    (define (make-general-closure env body nreq rest? nopt kw inits alt)
      (define alt-proc
        (and alt                             ; (body docstring nreq ...)
             (let* ((body (car alt))
                    (spec (cddr alt))
                    (nreq (car spec))
                    (rest (if (null? (cdr spec)) #f (cadr spec)))
                    (tail (and (pair? (cdr spec)) (pair? (cddr spec)) (cddr spec)))
                    (nopt (if tail (car tail) 0))
                    (kw (and tail (cadr tail)))
                    (inits (if tail (caddr tail) '()))
                    (alt (and tail (cadddr tail))))
               (make-general-closure env body nreq rest nopt kw inits alt))))
      (define (set-procedure-arity! proc)
        (let lp ((alt alt) (nreq nreq) (nopt nopt) (rest? rest?))
          (if (not alt)
              (begin
                (set-procedure-property! proc 'arglist
                                         (list nreq
                                               nopt
                                               (if kw (cdr kw) '())
                                               (and kw (car kw))
                                               (and rest? '_)))
                (set-procedure-minimum-arity! proc nreq nopt rest?))
              (let* ((spec (cddr alt))
                     (nreq* (car spec))
                     (rest?* (if (null? (cdr spec)) #f (cadr spec)))
                     (tail (and (pair? (cdr spec)) (pair? (cddr spec)) (cddr spec)))
                     (nopt* (if tail (car tail) 0))
                     (alt* (and tail (cadddr tail))))
                (if (or (< nreq* nreq)
                        (and (= nreq* nreq)
                             (if rest?
                                 (and rest?* (> nopt* nopt))
                                 (or rest?* (> nopt* nopt)))))
                    (lp alt* nreq* nopt* rest?*)
                    (lp alt* nreq nopt rest?)))))
        proc)
      (set-procedure-arity!
       (lambda %args
         (let lp ((env env)
                  (nreq* nreq)
                  (args %args))
           (if (> nreq* 0)
               ;; First, bind required arguments.
               (if (null? args)
                   (if alt
                       (apply alt-proc %args)
                       (scm-error 'wrong-number-of-args
                                  "eval" "Wrong number of arguments"
                                  '() #f))
                   (lp (cons (car args) env)
                       (1- nreq*)
                       (cdr args)))
               ;; Move on to optional arguments.
               (if (not kw)
                   ;; Without keywords, bind optionals from arguments.
                   (let lp ((env env)
                            (nopt nopt)
                            (args args)
                            (inits inits))
                     (if (zero? nopt)
                         (if rest?
                             (eval body (cons args env))
                             (if (null? args)
                                 (eval body env)
                                 (if alt
                                     (apply alt-proc %args)
                                     (scm-error 'wrong-number-of-args
                                                "eval" "Wrong number of arguments"
                                                '() #f))))
                         (if (null? args)
                             (lp (cons (eval (car inits) env) env)
                                 (1- nopt) args (cdr inits))
                             (lp (cons (car args) env)
                                 (1- nopt) (cdr args) (cdr inits)))))
                   ;; With keywords, we stop binding optionals at the first
                   ;; keyword.
                   (let lp ((env env)
                            (nopt* nopt)
                            (args args)
                            (inits inits))
                     (if (> nopt* 0)
                         (if (or (null? args) (keyword? (car args)))
                             (lp (cons (eval (car inits) env) env)
                                 (1- nopt*) args (cdr inits))
                             (lp (cons (car args) env)
                                 (1- nopt*) (cdr args) (cdr inits)))
                         ;; Finished with optionals.
                         (let* ((aok (car kw))
                                (kw (cdr kw))
                                (kw-base (+ nopt nreq (if rest? 1 0)))
                                (imax (let lp ((imax (1- kw-base)) (kw kw))
                                        (if (null? kw)
                                            imax
                                            (lp (max (cdar kw) imax)
                                                (cdr kw)))))
                                ;; Fill in kwargs  with "undefined" vals.
                                (env (let lp ((i kw-base)
                                              ;; Also, here we bind the rest
                                              ;; arg, if any.
                                              (env (if rest? (cons args env) env)))
                                       (if (<= i imax)
                                           (lp (1+ i) (cons unbound-arg env))
                                           env))))
                           ;; Now scan args for keywords.
                           (let lp ((args args))
                             (if (and (pair? args) (pair? (cdr args))
                                      (keyword? (car args)))
                                 (let ((kw-pair (assq (car args) kw))
                                       (v (cadr args)))
                                   (if kw-pair
                                       ;; Found a known keyword; set its value.
                                       (list-set! env (- imax (cdr kw-pair)) v)
                                       ;; Unknown keyword.
                                       (if (not aok)
                                           (scm-error 'keyword-argument-error
                                                      "eval" "Unrecognized keyword"
                                                      '() #f)))
                                   (lp (cddr args)))
                                 (if (pair? args)
                                     (if rest?
                                         ;; Be lenient parsing rest args.
                                         (lp (cdr args))
                                         (scm-error 'keyword-argument-error
                                                    "eval" "Invalid keyword"
                                                    '() #f))
                                     ;; Finished parsing keywords. Fill in
                                     ;; uninitialized kwargs by evalling init
                                     ;; expressions in their appropriate
                                     ;; environment.
                                     (let lp ((i (- imax kw-base))
                                              (inits inits))
                                       (if (pair? inits)
                                           (let ((tail (list-tail env i)))
                                             (if (eq? (car tail) unbound-arg)
                                                 (set-car! tail
                                                           (eval (car inits)
                                                                 (cdr tail))))
                                             (lp (1- i) (cdr inits)))
                                           ;; Finally, eval the body.
                                           (eval body env)))))))))))))))

    ;; The "engine". EXP is a memoized expression.
    (define (eval exp env)
      (memoized-expression-case exp
        (('lexical-ref n)
         (list-ref env n))
        
        (('call (f nargs . args))
         (let ((proc (eval f env)))
           (call eval proc nargs args env)))
        
        (('toplevel-ref var-or-sym)
         (variable-ref
          (if (variable? var-or-sym)
              var-or-sym
              (memoize-variable-access! exp
                                        (capture-env (if (pair? env)
                                                         (cdr (last-pair env))
                                                         env))))))

        (('if (test consequent . alternate))
         (if (eval test env)
             (eval consequent env)
             (eval alternate env)))
      
        (('quote x)
         x)

        (('let (inits . body))
         (let lp ((inits inits) (new-env (capture-env env)))
           (if (null? inits)
               (eval body new-env)
               (lp (cdr inits)
                   (cons (eval (car inits) env) new-env)))))

        (('lambda (body docstring nreq . tail))
         (let ((proc
                (if (null? tail)
                    (make-fixed-closure eval nreq body (capture-env env))
                    (if (null? (cdr tail))
                        (make-general-closure (capture-env env) body
                                              nreq (car tail)
                                              0 #f '() #f)
                        (apply make-general-closure (capture-env env)
                               body nreq tail)))))
           (when docstring
             (set-procedure-property! proc 'documentation docstring))
           proc))

        (('begin (first . rest))
         (let lp ((first first) (rest rest))
           (if (null? rest)
               (eval first env)
               (begin
                 (eval first env)
                 (lp (car rest) (cdr rest))))))
      
        (('lexical-set! (n . x))
         (let ((val (eval x env)))
           (list-set! env n val)))
        
        (('call-with-values (producer . consumer))
         (call-with-values (eval producer env)
           (eval consumer env)))

        (('apply (f args))
         (apply (eval f env) (eval args env)))

        (('module-ref var-or-spec)
         (variable-ref
          (if (variable? var-or-spec)
              var-or-spec
              (memoize-variable-access! exp #f))))

        (('define (name . x))
         (let ((x (eval x env)))
           (if (and (procedure? x) (not (procedure-property x 'name)))
               (set-procedure-property! x 'name name))
           (define! name x)
           (if #f #f)))
      
        (('toplevel-set! (var-or-sym . x))
         (variable-set!
          (if (variable? var-or-sym)
              var-or-sym
              (memoize-variable-access! exp
                                        (capture-env (if (pair? env)
                                                         (cdr (last-pair env))
                                                         env))))
          (eval x env)))
      
        (('dynwind (in exp . out))
         (dynamic-wind (eval in env)
                       (lambda () (eval exp env))
                       (eval out env)))
        
        (('with-fluids (fluids vals . exp))
         (let* ((fluids (map (lambda (x) (eval x env)) fluids))
                (vals (map (lambda (x) (eval x env)) vals)))
           (let lp ((fluids fluids) (vals vals))
             (if (null? fluids)
                 (eval exp env)
                 (with-fluids (((car fluids) (car vals)))
                   (lp (cdr fluids) (cdr vals)))))))
        
        (('prompt (tag exp . handler))
         (@prompt (eval tag env)
                  (eval exp env)
                  (eval handler env)))
        
        (('call/cc proc)
         (call/cc (eval proc env)))

        (('module-set! (x . var-or-spec))
         (variable-set!
          (if (variable? var-or-spec)
              var-or-spec
              (memoize-variable-access! exp #f))
          (eval x env)))))
  
    ;; primitive-eval
    (lambda (exp)
      "Evaluate @var{exp} in the current module."
      (eval 
       (memoize-expression 
        (if (macroexpanded? exp)
            exp
            ((module-transformer (current-module)) exp)))
       '()))))
Commit	Line	Data
5161a3c0 AW	1	;;; -- mode: scheme; coding: utf-8; --
5161a3c0 AW	2
c438cd71	3	;;;; Copyright (C) 2009, 2010, 2012 Free Software Foundation, Inc.
5161a3c0 AW	4	;;;;
	5	;;;; This library is free software; you can redistribute it and/or
	6	;;;; modify it under the terms of the GNU Lesser General Public
	7	;;;; License as published by the Free Software Foundation; either
	8	;;;; version 3 of the License, or (at your option) any later version.
	9	;;;;
	10	;;;; This library is distributed in the hope that it will be useful,
	11	;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	13	;;;; Lesser General Public License for more details.
	14	;;;;
	15	;;;; You should have received a copy of the GNU Lesser General Public
	16	;;;; License along with this library; if not, write to the Free Software
	17	;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	18	;;;;
	19
	20	\f
	21
	22	;;; Commentary:
	23
b2b554ef AW	24	;;; Scheme eval, written in Scheme.
	25	;;;
	26	;;; Expressions are first expanded, by the syntax expander (i.e.
	27	;;; psyntax), then memoized into internal forms. The evaluator itself
	28	;;; only operates on the internal forms ("memoized expressions").
	29	;;;
	30	;;; Environments are represented as linked lists of the form (VAL ... .
	31	;;; MOD). If MOD is #f, it means the environment was captured before
	32	;;; modules were booted. If MOD is the literal value '(), we are
	33	;;; evaluating at the top level, and so should track changes to the
	34	;;; current module.
	35	;;;
	36	;;; Evaluate this in Emacs to make code indentation work right:
	37	;;;
	38	;;; (put 'memoized-expression-case 'scheme-indent-function 1)
5161a3c0 AW	39	;;;
	40
	41	;;; Code:
	42
	43	\f
	44
5161a3c0 AW	45	(eval-when (compile)
	46	(define-syntax capture-env
	47	(syntax-rules ()
bb0c8157 AW	48	((_ (exp ...))
	49	(let ((env (exp ...)))
	50	(capture-env env)))
5161a3c0 AW	51	((_ env)
	52	(if (null? env)
	53	(current-module)
	54	(if (not env)
b2b554ef AW	55	;; the and current-module checks that modules are booted,
b2b554ef AW	56	;; and thus the-root-module is defined
5f161164	57	(and (current-module) the-root-module)
5161a3c0 AW	58	env)))))
5161a3c0 AW	59
d8a071fc AW	60	;; Fast case for procedures with fixed arities.
d8a071fc AW	61	(define-syntax make-fixed-closure
4abb824c	62	(lambda (x)
9331f91c	63	(define max-static-argument-count 8)
4abb824c AW	64	(define (make-formals n)
	65	(map (lambda (i)
	66	(datum->syntax
c438cd71	67	x
4abb824c AW	68	(string->symbol
	69	(string (integer->char (+ (char->integer #\a) i))))))
	70	(iota n)))
	71	(syntax-case x ()
d8a071fc	72	((_ eval nreq body env) (not (identifier? #'env))
4abb824c	73	#'(let ((e env))
d8a071fc AW	74	(make-fixed-closure eval nreq body e)))
d8a071fc AW	75	((_ eval nreq body env)
4abb824c AW	76	#`(case nreq
	77	#,@(map (lambda (nreq)
	78	(let ((formals (make-formals nreq)))
	79	#`((#,nreq)
d8a071fc AW	80	(lambda (#,@formals)
	81	(eval body
	82	(cons* #,@(reverse formals) env))))))
4abb824c AW	83	(iota max-static-argument-count))
	84	(else
	85	#,(let ((formals (make-formals max-static-argument-count)))
	86	#`(lambda (#,@formals . more)
	87	(let lp ((new-env (cons* #,@(reverse formals) env))
	88	(nreq (- nreq #,max-static-argument-count))
	89	(args more))
	90	(if (zero? nreq)
	91	(eval body
d8a071fc AW	92	(if (null? args)
	93	new-env
	94	(scm-error 'wrong-number-of-args
	95	"eval" "Wrong number of arguments"
	96	'() #f)))
4abb824c AW	97	(if (null? args)
	98	(scm-error 'wrong-number-of-args
	99	"eval" "Wrong number of arguments"
	100	'() #f)
	101	(lp (cons (car args) new-env)
	102	(1- nreq)
	103	(cdr args)))))))))))))
	104
9331f91c AW	105	(define-syntax call
	106	(lambda (x)
	107	(define max-static-call-count 4)
	108	(syntax-case x ()
	109	((_ eval proc nargs args env) (identifier? #'env)
	110	#`(case nargs
	111	#,@(map (lambda (nargs)
	112	#`((#,nargs)
	113	(proc
	114	#,@(map
	115	(lambda (n)
	116	(let lp ((n n) (args #'args))
	117	(if (zero? n)
	118	#`(eval (car #,args) env)
	119	(lp (1- n) #`(cdr #,args)))))
	120	(iota nargs)))))
	121	(iota max-static-call-count))
	122	(else
	123	(apply proc
	124	#,@(map
	125	(lambda (n)
	126	(let lp ((n n) (args #'args))
	127	(if (zero? n)
	128	#`(eval (car #,args) env)
	129	(lp (1- n) #`(cdr #,args)))))
	130	(iota max-static-call-count))
	131	(let lp ((exps #,(let lp ((n max-static-call-count)
	132	(args #'args))
	133	(if (zero? n)
	134	args
	135	(lp (1- n) #`(cdr #,args)))))
	136	(args '()))
	137	(if (null? exps)
	138	(reverse args)
	139	(lp (cdr exps)
	140	(cons (eval (car exps) env) args)))))))))))
	141
b2b554ef AW	142	;; This macro could be more straightforward if the compiler had better
b2b554ef AW	143	;; copy propagation. As it is we do some copy propagation by hand.
5161a3c0 AW	144	(define-syntax mx-bind
	145	(lambda (x)
	146	(syntax-case x ()
	147	((_ data () body)
	148	#'body)
	149	((_ data (a . b) body) (and (identifier? #'a) (identifier? #'b))
	150	#'(let ((a (car data))
	151	(b (cdr data)))
	152	body))
	153	((_ data (a . b) body) (identifier? #'a)
	154	#'(let ((a (car data))
	155	(xb (cdr data)))
	156	(mx-bind xb b body)))
	157	((_ data (a . b) body)
	158	#'(let ((xa (car data))
	159	(xb (cdr data)))
	160	(mx-bind xa a (mx-bind xb b body))))
	161	((_ data v body) (identifier? #'v)
	162	#'(let ((v data))
	163	body)))))
	164
b2b554ef AW	165	;; The resulting nested if statements will be an O(n) dispatch. Once
b2b554ef AW	166	;; we compile `case' effectively, this situation will improve.
5161a3c0 AW	167	(define-syntax mx-match
	168	(lambda (x)
	169	(syntax-case x (quote)
	170	((_ mx data tag)
	171	#'(error "what" mx))
	172	((_ mx data tag (('type pat) body) c* ...)
	173	#`(if (eqv? tag #,(or (memoized-typecode (syntax->datum #'type))
	174	(error "not a typecode" #'type)))
	175	(mx-bind data pat body)
	176	(mx-match mx data tag c* ...))))))
	177
	178	(define-syntax memoized-expression-case
	179	(lambda (x)
	180	(syntax-case x ()
	181	((_ mx c ...)
	182	#'(let ((tag (memoized-expression-typecode mx))
	183	(data (memoized-expression-data mx)))
	184	(mx-match mx data tag c ...)))))))
	185
	186
21ec0bd9 AW	187	;;;
	188	;;; On 18 Feb 2010, I did a profile of how often the various memoized expression
	189	;;; types occur when getting to a prompt on a fresh build. Here are the numbers
	190	;;; I got:
	191	;;;
	192	;;; lexical-ref: 32933054
	193	;;; call: 20281547
	194	;;; toplevel-ref: 13228724
	195	;;; if: 9156156
	196	;;; quote: 6610137
	197	;;; let: 2619707
	198	;;; lambda: 1010921
	199	;;; begin: 948945
	200	;;; lexical-set: 509862
	201	;;; call-with-values: 139668
	202	;;; apply: 49402
	203	;;; module-ref: 14468
	204	;;; define: 1259
	205	;;; toplevel-set: 328
	206	;;; dynwind: 162
	207	;;; with-fluids: 0
	208	;;; call/cc: 0
	209	;;; module-set: 0
	210	;;;
	211	;;; So until we compile `case' into a computed goto, we'll order the clauses in
	212	;;; `eval' in this order, to put the most frequent cases first.
	213	;;;
	214
5161a3c0 AW	215	(define primitive-eval
5161a3c0 AW	216	(let ()
d8a071fc AW	217	;; We pre-generate procedures with fixed arities, up to some number of
	218	;; arguments; see make-fixed-closure above.
	219
	220	;; A unique marker for unbound keywords.
	221	(define unbound-arg (list 'unbound-arg))
	222
7572ee52 AW	223	;; Procedures with rest, optional, or keyword arguments, potentially with
7572ee52 AW	224	;; multiple arities, as with case-lambda.
d8a071fc	225	(define (make-general-closure env body nreq rest? nopt kw inits alt)
7572ee52	226	(define alt-proc
c438cd71	227	(and alt ; (body docstring nreq ...)
dc3e203e	228	(let* ((body (car alt))
c438cd71 LC	229	(spec (cddr alt))
	230	(nreq (car spec))
	231	(rest (if (null? (cdr spec)) #f (cadr spec)))
	232	(tail (and (pair? (cdr spec)) (pair? (cddr spec)) (cddr spec)))
dc3e203e AW	233	(nopt (if tail (car tail) 0))
	234	(kw (and tail (cadr tail)))
	235	(inits (if tail (caddr tail) '()))
	236	(alt (and tail (cadddr tail))))
	237	(make-general-closure env body nreq rest nopt kw inits alt))))
f3cf9421 AW	238	(define (set-procedure-arity! proc)
	239	(let lp ((alt alt) (nreq nreq) (nopt nopt) (rest? rest?))
	240	(if (not alt)
fc835b1b AW	241	(begin
	242	(set-procedure-property! proc 'arglist
	243	(list nreq
	244	nopt
	245	(if kw (cdr kw) '())
	246	(and kw (car kw))
	247	(and rest? '_)))
	248	(set-procedure-minimum-arity! proc nreq nopt rest?))
c438cd71 LC	249	(let* ((spec (cddr alt))
	250	(nreq* (car spec))
	251	(rest?* (if (null? (cdr spec)) #f (cadr spec)))
	252	(tail (and (pair? (cdr spec)) (pair? (cddr spec)) (cddr spec)))
f3cf9421 AW	253	(nopt* (if tail (car tail) 0))
	254	(alt* (and tail (cadddr tail))))
	255	(if (or (< nreq* nreq)
	256	(and (= nreq* nreq)
	257	(if rest?
	258	(and rest?* (> nopt* nopt))
	259	(or rest?* (> nopt* nopt)))))
	260	(lp alt* nreq* nopt* rest?*)
	261	(lp alt* nreq nopt rest?)))))
	262	proc)
	263	(set-procedure-arity!
	264	(lambda %args
	265	(let lp ((env env)
	266	(nreq* nreq)
	267	(args %args))
	268	(if (> nreq* 0)
	269	;; First, bind required arguments.
	270	(if (null? args)
	271	(if alt
	272	(apply alt-proc %args)
	273	(scm-error 'wrong-number-of-args
	274	"eval" "Wrong number of arguments"
	275	'() #f))
	276	(lp (cons (car args) env)
	277	(1- nreq*)
	278	(cdr args)))
	279	;; Move on to optional arguments.
	280	(if (not kw)
	281	;; Without keywords, bind optionals from arguments.
	282	(let lp ((env env)
	283	(nopt nopt)
	284	(args args)
	285	(inits inits))
	286	(if (zero? nopt)
	287	(if rest?
	288	(eval body (cons args env))
	289	(if (null? args)
	290	(eval body env)
	291	(if alt
	292	(apply alt-proc %args)
	293	(scm-error 'wrong-number-of-args
	294	"eval" "Wrong number of arguments"
	295	'() #f))))
	296	(if (null? args)
	297	(lp (cons (eval (car inits) env) env)
	298	(1- nopt) args (cdr inits))
	299	(lp (cons (car args) env)
	300	(1- nopt) (cdr args) (cdr inits)))))
	301	;; With keywords, we stop binding optionals at the first
	302	;; keyword.
	303	(let lp ((env env)
	304	(nopt* nopt)
	305	(args args)
	306	(inits inits))
	307	(if (> nopt* 0)
	308	(if (or (null? args) (keyword? (car args)))
	309	(lp (cons (eval (car inits) env) env)
	310	(1- nopt*) args (cdr inits))
	311	(lp (cons (car args) env)
	312	(1- nopt*) (cdr args) (cdr inits)))
	313	;; Finished with optionals.
	314	(let* ((aok (car kw))
	315	(kw (cdr kw))
	316	(kw-base (+ nopt nreq (if rest? 1 0)))
317	(imax (let lp ((imax (1- kw-base)) (kw kw))
318	(if (null? kw)
319	imax
320	(lp (max (cdar kw) imax)
321	(cdr kw)))))
322	;; Fill in kwargs with "undefined" vals.
323	(env (let lp ((i kw-base)
324	;; Also, here we bind the rest
325	;; arg, if any.
326	(env (if rest? (cons args env) env)))
327	(if (<= i imax)
328	(lp (1+ i) (cons unbound-arg env))
329	env))))
330	;; Now scan args for keywords.
331	(let lp ((args args))
332	(if (and (pair? args) (pair? (cdr args))
333	(keyword? (car args)))
334	(let ((kw-pair (assq (car args) kw))
335	(v (cadr args)))
336	(if kw-pair
337	;; Found a known keyword; set its value.
338	(list-set! env (- imax (cdr kw-pair)) v)
339	;; Unknown keyword.
340	(if (not aok)
341	(scm-error 'keyword-argument-error
342	"eval" "Unrecognized keyword"
343	'() #f)))
344	(lp (cddr args)))
345	(if (pair? args)
346	(if rest?
347	;; Be lenient parsing rest args.
348	(lp (cdr args))
349	(scm-error 'keyword-argument-error
350	"eval" "Invalid keyword"
351	'() #f))
352	;; Finished parsing keywords. Fill in
353	;; uninitialized kwargs by evalling init
354	;; expressions in their appropriate
355	;; environment.
356	(let lp ((i (- imax kw-base))
357	(inits inits))
358	(if (pair? inits)
359	(let ((tail (list-tail env i)))
360	(if (eq? (car tail) unbound-arg)
361	(set-car! tail
362	(eval (car inits)
363	(cdr tail))))
364	(lp (1- i) (cdr inits)))
365	;; Finally, eval the body.
366	(eval body env)))))))))))))))
d8a071fc	367
b2b554ef	368	;; The "engine". EXP is a memoized expression.
5161a3c0 AW	369	(define (eval exp env)
5161a3c0 AW	370	(memoized-expression-case exp
21ec0bd9	371	(('lexical-ref n)
bb0c8157 AW	372	(list-ref env n))
bb0c8157 AW	373
21ec0bd9 AW	374	(('call (f nargs . args))
	375	(let ((proc (eval f env)))
	376	(call eval proc nargs args env)))
	377
	378	(('toplevel-ref var-or-sym)
	379	(variable-ref
	380	(if (variable? var-or-sym)
	381	var-or-sym
bb0c8157 AW	382	(memoize-variable-access! exp
	383	(capture-env (if (pair? env)
	384	(cdr (last-pair env))
	385	env))))))
21ec0bd9	386
5161a3c0 AW	387	(('if (test consequent . alternate))
	388	(if (eval test env)
	389	(eval consequent env)
	390	(eval alternate env)))
	391
21ec0bd9 AW	392	(('quote x)
	393	x)
	394
5161a3c0 AW	395	(('let (inits . body))
	396	(let lp ((inits inits) (new-env (capture-env env)))
	397	(if (null? inits)
	398	(eval body new-env)
	399	(lp (cdr inits)
	400	(cons (eval (car inits) env) new-env)))))
c438cd71 LC	401
	402	(('lambda (body docstring nreq . tail))
	403	(let ((proc
	404	(if (null? tail)
	405	(make-fixed-closure eval nreq body (capture-env env))
	406	(if (null? (cdr tail))
	407	(make-general-closure (capture-env env) body
	408	nreq (car tail)
	409	0 #f '() #f)
	410	(apply make-general-closure (capture-env env)
	411	body nreq tail)))))
	412	(when docstring
	413	(set-procedure-property! proc 'documentation docstring))
	414	proc))
d8a071fc	415
21ec0bd9 AW	416	(('begin (first . rest))
	417	(let lp ((first first) (rest rest))
	418	(if (null? rest)
	419	(eval first env)
	420	(begin
	421	(eval first env)
	422	(lp (car rest) (cdr rest))))))
5161a3c0 AW	423
	424	(('lexical-set! (n . x))
	425	(let ((val (eval x env)))
bb0c8157	426	(list-set! env n val)))
5161a3c0	427
21ec0bd9 AW	428	(('call-with-values (producer . consumer))
	429	(call-with-values (eval producer env)
	430	(eval consumer env)))
	431
	432	(('apply (f args))
	433	(apply (eval f env) (eval args env)))
	434
	435	(('module-ref var-or-spec)
5161a3c0	436	(variable-ref
21ec0bd9 AW	437	(if (variable? var-or-spec)
	438	var-or-spec
	439	(memoize-variable-access! exp #f))))
5161a3c0	440
21ec0bd9	441	(('define (name . x))
ee15aa46 AW	442	(let ((x (eval x env)))
	443	(if (and (procedure? x) (not (procedure-property x 'name)))
	444	(set-procedure-property! x 'name name))
adb8054c MW	445	(define! name x)
adb8054c MW	446	(if #f #f)))
21ec0bd9	447
5161a3c0 AW	448	(('toplevel-set! (var-or-sym . x))
	449	(variable-set!
	450	(if (variable? var-or-sym)
	451	var-or-sym
bb0c8157 AW	452	(memoize-variable-access! exp
	453	(capture-env (if (pair? env)
	454	(cdr (last-pair env))
	455	env))))
5161a3c0 AW	456	(eval x env)))
5161a3c0 AW	457
21ec0bd9 AW	458	(('dynwind (in exp . out))
	459	(dynamic-wind (eval in env)
	460	(lambda () (eval exp env))
	461	(eval out env)))
	462
bb0229b5 AW	463	(('with-fluids (fluids vals . exp))
	464	(let* ((fluids (map (lambda (x) (eval x env)) fluids))
	465	(vals (map (lambda (x) (eval x env)) vals)))
1371fe9b AW	466	(let lp ((fluids fluids) (vals vals))
	467	(if (null? fluids)
	468	(eval exp env)
	469	(with-fluids (((car fluids) (car vals)))
	470	(lp (cdr fluids) (cdr vals)))))))
bb0229b5	471
747022e4 AW	472	(('prompt (tag exp . handler))
	473	(@prompt (eval tag env)
	474	(eval exp env)
	475	(eval handler env)))
	476
21ec0bd9 AW	477	(('call/cc proc)
21ec0bd9 AW	478	(call/cc (eval proc env)))
5161a3c0 AW	479
	480	(('module-set! (x . var-or-spec))
	481	(variable-set!
	482	(if (variable? var-or-spec)
	483	var-or-spec
	484	(memoize-variable-access! exp #f))
	485	(eval x env)))))
	486
b2b554ef	487	;; primitive-eval
5161a3c0	488	(lambda (exp)
b2b554ef	489	"Evaluate @var{exp} in the current module."
5161a3c0	490	(eval
a310a1d1 AW	491	(memoize-expression
	492	(if (macroexpanded? exp)
	493	exp
	494	((module-transformer (current-module)) exp)))
5161a3c0	495	'()))))