/
srfi-149.ss
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srfi-149.ss
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#|
Copyright (c) 2009-2021 Alex Shinn All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
3. The name of the author may not be used to endorse or promote products
derived from this software without specific prior written permission.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|#
(define-library (srfi 149)
(import (only (meevax core) define-syntax quote-syntax)
(only (meevax macro-transformer) er-macro-transformer identifier?)
(only (meevax symbol) identifier->symbol)
(scheme r4rs))
(export syntax-rules)
(begin (define %number->string number->string)
(define (length* ls1) ; Chibi-Scheme's sexp_length_op (sexp.c)
(if (not (pair? ls1))
0
(let length* ((ls1 ls1)
(ls2 (cdr ls1))
(res 1))
(if (and (pair? ls2)
(pair? (cdr ls2)))
(if (eq? ls1 ls2)
#f
(length* (cdr ls1)
(cddr ls2)
(+ res 2)))
(+ res (if (pair? ls2) 1 0))))))
(define cons-source cons)
(define syntax-quote quote-syntax)
(define (strip-syntactic-closures x) x)
(define (any f xs)
(if (pair? xs)
(or (f (car xs))
(any f (cdr xs)))
#f))
(define (find f xs)
(if (pair? xs)
(if (f (car xs))
(car xs)
(find f (cdr xs)))
#f)))
(begin (define (syntax-rules-transformer expr rename compare)
(let ((ellipsis-specified? (identifier? (cadr expr)))
(count 0)
(_er-macro-transformer (rename 'er-macro-transformer))
(_lambda (rename 'lambda)) (_let (rename 'let))
(_begin (rename 'begin)) (_if (rename 'if))
(_and (rename 'and)) (_or (rename 'or))
(_eq? (rename 'eq?)) (_equal? (rename 'equal?))
(_car (rename 'car)) (_cdr (rename 'cdr))
(_cons (rename 'cons)) (_pair? (rename 'pair?))
(_null? (rename 'null?)) (_expr (rename 'expr))
(_rename (rename 'rename)) (_compare (rename 'compare))
(_quote (rename 'syntax-quote)) (_apply (rename 'apply))
(_append (rename 'append)) (_map (rename 'map))
(_vector? (rename 'vector?)) (_list? (rename 'list?))
(_len (rename'len)) (_length (rename 'length*))
(_- (rename '-)) (_>= (rename '>=)) (_error (rename 'error))
(_ls (rename 'ls)) (_res (rename 'res)) (_i (rename 'i))
(_reverse (rename 'reverse))
(_vector->list (rename 'vector->list))
(_list->vector (rename 'list->vector))
(_cons3 (rename 'cons-source))
(_underscore (rename '_)))
(define ellipsis (if ellipsis-specified? (cadr expr) (rename '...)))
(define lits (if ellipsis-specified? (car (cddr expr)) (cadr expr)))
(define forms (if ellipsis-specified? (cdr (cddr expr)) (cddr expr)))
(define (next-symbol s)
(set! count (+ count 1))
(rename (string->symbol (string-append s (%number->string count)))))
(define (expand-pattern pat tmpl)
(let lp ((p (cdr pat))
(x (list _cdr _expr))
(dim 0)
(vars '())
(k (lambda (vars)
(list _cons (expand-template tmpl vars) #f))))
(let ((v (next-symbol "v.")))
(list
_let (list (list v x))
(cond
((identifier? p)
(if (any (lambda (l) (compare p l)) lits)
(list _and
(list _compare v (list _rename (list _quote p)))
(k vars))
(if (compare p _underscore)
(k vars)
(list _let (list (list p v)) (k (cons (cons p dim) vars))))))
((ellipsis? p)
(cond
((not (null? (cdr (cdr p))))
(cond
((any (lambda (x) (and (identifier? x) (compare x ellipsis)))
(cddr p))
(error "multiple ellipses" p))
(else
(let ((len (length* (cdr (cdr p))))
(_lp (next-symbol "lp.")))
`(,_let ((,_len (,_length ,v)))
(,_and (,_>= ,_len ,len)
(,_let ,_lp ((,_ls ,v)
(,_i (,_- ,_len ,len))
(,_res (,_quote ())))
(,_if (,_>= 0 ,_i)
,(lp `(,(cddr p)
(,(car p) ,(car (cdr p))))
`(,_cons ,_ls
(,_cons (,_reverse ,_res)
(,_quote ())))
dim
vars
k)
(,_lp (,_cdr ,_ls)
(,_- ,_i 1)
(,_cons3 (,_car ,_ls)
,_res
,_ls))))))))))
((identifier? (car p))
(list _and (list _list? v)
(list _let (list (list (car p) v))
(k (cons (cons (car p) (+ 1 dim)) vars)))))
(else
(let* ((w (next-symbol "w."))
(_lp (next-symbol "lp."))
(new-vars (all-vars (car p) (+ dim 1)))
(ls-vars (map (lambda (x)
(next-symbol
(string-append
(symbol->string
(identifier->symbol (car x)))
"-ls")))
new-vars))
(once
(lp (car p) (list _car w) (+ dim 1) '()
(lambda (_)
(cons
_lp
(cons
(list _cdr w)
(map (lambda (x l)
(list _cons (car x) l))
new-vars
ls-vars)))))))
(list
_let
_lp (cons (list w v)
(map (lambda (x) (list x (list _quote '()))) ls-vars))
(list _if (list _null? w)
(list _let (map (lambda (x l)
(list (car x) (list _reverse l)))
new-vars
ls-vars)
(k (append new-vars vars)))
(list _and (list _pair? w) once)))))))
((pair? p)
(list _and (list _pair? v)
(lp (car p)
(list _car v)
dim
vars
(lambda (vars)
(lp (cdr p) (list _cdr v) dim vars k)))))
((vector? p)
(list _and
(list _vector? v)
(lp (vector->list p) (list _vector->list v) dim vars k)))
((null? p) (list _and (list _null? v) (k vars)))
(else (list _and (list _equal? v p) (k vars))))))))
(define (ellipsis-escape? x) (and (pair? x) (compare ellipsis (car x))))
(define (ellipsis? x)
(and (pair? x) (pair? (cdr x)) (compare ellipsis (cadr x))))
(define (ellipsis-depth x)
(if (ellipsis? x)
(+ 1 (ellipsis-depth (cdr x)))
0))
(define (ellipsis-tail x)
(if (ellipsis? x)
(ellipsis-tail (cdr x))
(cdr x)))
(define (all-vars x dim)
(let lp ((x x) (dim dim) (vars '()))
(cond ((identifier? x)
(if (any (lambda (lit) (compare x lit)) lits)
vars
(cons (cons x dim) vars)))
((ellipsis? x) (lp (car x) (+ dim 1) (lp (cddr x) dim vars)))
((pair? x) (lp (car x) dim (lp (cdr x) dim vars)))
((vector? x) (lp (vector->list x) dim vars))
(else vars))))
(define (free-vars x vars dim)
(let lp ((x x) (free '()))
(cond
((identifier? x)
(if (and (not (memq x free))
(cond ((assq x vars) => (lambda (cell) (>= (cdr cell) dim)))
(else #f)))
(cons x free)
free))
((pair? x) (lp (car x) (lp (cdr x) free)))
((vector? x) (lp (vector->list x) free))
(else free))))
(define (expand-template tmpl vars)
(let lp ((t tmpl) (dim 0))
(cond
((identifier? t)
(cond
((find (lambda (v) (eq? t (car v))) vars)
=> (lambda (cell)
(if (<= (cdr cell) dim)
t
(error "too few ...'s"))))
(else
(list _rename (list _quote t)))))
((pair? t)
(cond
((ellipsis-escape? t)
(list _quote
(if (pair? (cdr t))
(if (pair? (cddr t)) (cddr t) (cadr t))
(cdr t))))
((ellipsis? t)
(let* ((depth (ellipsis-depth t))
(ell-dim (+ dim depth))
(ell-vars (free-vars (car t) vars ell-dim)))
(cond
((null? ell-vars)
(error "too many ...'s"))
((and (null? (cdr (cdr t))) (identifier? (car t)))
;; shortcut for (var ...)
(lp (car t) ell-dim))
(else
(let* ((once (lp (car t) ell-dim))
(nest (if (and (null? (cdr ell-vars))
(identifier? once)
(eq? once (car vars)))
once ;; shortcut
(cons _map
(cons (list _lambda ell-vars once)
ell-vars))))
(many (do ((d depth (- d 1))
(many nest
(list _apply _append many)))
((= d 1) many))))
(if (null? (ellipsis-tail t))
many ;; shortcut
(list _append many (lp (ellipsis-tail t) dim))))))))
(else (list _cons3 (lp (car t) dim) (lp (cdr t) dim) (list _quote t)))))
((vector? t) (list _list->vector (lp (vector->list t) dim)))
((null? t) (list _quote '()))
(else t))))
(list
_er-macro-transformer
(list _lambda (list _expr _rename _compare)
(list
_car
(cons
_or
(append
(map
(lambda (clause) (expand-pattern (car clause) (cadr clause)))
forms)
(list
(list _cons
(list _error "no expansion for"
(list (rename 'strip-syntactic-closures) _expr))
#f)))))))))
(define-syntax syntax-rules
(er-macro-transformer
(lambda (form rename compare)
(syntax-rules-transformer form rename compare))))))