485 lines
18 KiB
Racket
485 lines
18 KiB
Racket
#lang racket/base
|
|
(require (for-syntax racket/base
|
|
racket/set
|
|
racket/syntax
|
|
racket/match
|
|
racket/private/sc
|
|
unstable/struct)
|
|
racket/match
|
|
racket/vector
|
|
syntax/stx
|
|
syntax/parse/private/residual
|
|
unstable/struct)
|
|
(provide template
|
|
define-template-metafunction
|
|
??
|
|
?@)
|
|
|
|
#|
|
|
To do:
|
|
- improve error messages
|
|
- support flexible depths, eg
|
|
(with-syntax ([(a ...) #'(1 2 3)]
|
|
[((b ...) ...) #'((1 2 3) (4 5 6) (7 8 9))])
|
|
#'(((a b) ...) ...)) ;; a has depth 1, used at depth 2
|
|
|#
|
|
|
|
#|
|
|
A Template (T) is one of:
|
|
- pvar
|
|
- atom (including (), not pvar)
|
|
- (metafunction . T)
|
|
- (H . T)
|
|
- (H ... . T), (H ... ... . T), etc
|
|
- (?? T T)
|
|
- ... other standard compound forms
|
|
|
|
A HeadTemplate (H) is one of:
|
|
- T
|
|
- (?? T)
|
|
- (?@ . T)
|
|
|#
|
|
|
|
(define-syntax (template stx)
|
|
(parameterize ((current-syntax-context stx))
|
|
(syntax-case stx ()
|
|
[(template t)
|
|
(let-values ([(guide deps) (parse-template #'t)])
|
|
;; (eprintf "guide = ~s\n" guide)
|
|
(let ([vars
|
|
(for/list ([dep (in-vector deps)])
|
|
(cond [(syntax-pattern-variable? dep)
|
|
(let* ([valvar (syntax-mapping-valvar dep)]
|
|
[attr (syntax-local-value valvar (lambda () #f))])
|
|
(cond [(attribute-mapping? attr)
|
|
(attribute-mapping-var attr)]
|
|
[else valvar]))]
|
|
[(template-metafunction? dep)
|
|
(template-metafunction-var dep)]))])
|
|
(syntax-arm
|
|
(cond [(equal? guide '1) ;; was (template pvar)
|
|
(with-syntax ([var (car vars)])
|
|
#'(if (syntax? var)
|
|
var
|
|
(error/not-stx (quote-syntax t) var)))]
|
|
[(equal? guide '_) ;; constant
|
|
#`(quote-syntax t)]
|
|
[else
|
|
(with-syntax ([guide guide]
|
|
[(var ...) vars])
|
|
#'(substitute (quote-syntax t)
|
|
'guide
|
|
(vector var ...)))]))))])))
|
|
|
|
(define-syntaxes (?? ?@)
|
|
(let ([tx (lambda (stx) (raise-syntax-error #f "not allowed as an expression" stx))])
|
|
(values tx tx)))
|
|
|
|
;; ============================================================
|
|
|
|
#|
|
|
A Guide (G) is one of:
|
|
- _
|
|
- (G . G)
|
|
- integer
|
|
- #s(stxvector G)
|
|
- #s(stxstruct G)
|
|
- #&G
|
|
- #s(dots HG (vector-of integer) nat G)
|
|
- #s(app HG G)
|
|
- #s(escaped G)
|
|
- #s(orelse G (vector-of integer) G)
|
|
- #s(metafun integer G)
|
|
"optimized" forms:
|
|
- #s(sdots G integer G) ; simple head template, one driver, nesting=1
|
|
|
|
A HeadGuide (HG) is one of:
|
|
- G
|
|
- #s(app-opt G (vector-of integer))
|
|
- #s(splice G)
|
|
|
|
A Pre-Guide is like a Guide but with pvars and pvar sets instead of
|
|
integers and integer vectors.
|
|
|#
|
|
|
|
(define-syntax-rule (begin-both-phases form ...)
|
|
(begin (begin-for-syntax form ...)
|
|
(begin form ...)))
|
|
|
|
(begin-both-phases
|
|
(struct stxvector (g) #:prefab)
|
|
(struct stxstruct (g) #:prefab)
|
|
(struct dots (head hdrivers nesting tail) #:prefab)
|
|
(struct app (head tail) #:prefab)
|
|
(struct escaped (body) #:prefab)
|
|
(struct orelse (g1 drivers1 g2) #:prefab)
|
|
(struct metafun (index g) #:prefab)
|
|
(struct app-opt (g drivers) #:prefab)
|
|
(struct splice (g) #:prefab)
|
|
|
|
(struct sdots (head driver tail) #:prefab)
|
|
|
|
(define (head-guide? x)
|
|
(or (app-opt? x) (splice? x)))
|
|
)
|
|
|
|
;; ============================================================
|
|
|
|
(define-syntax (define-template-metafunction stx)
|
|
(syntax-case stx ()
|
|
[(dsm (id arg ...) . body)
|
|
#'(dsm id (lambda (arg ...) . body))]
|
|
[(dsm id expr)
|
|
(identifier? #'id)
|
|
(with-syntax ([(internal-id) (generate-temporaries #'(id))])
|
|
#'(begin (define internal-id expr)
|
|
(define-syntax id
|
|
(template-metafunction (quote-syntax internal-id)))))]))
|
|
|
|
(begin-for-syntax
|
|
(struct template-metafunction (var)))
|
|
|
|
;; ============================================================
|
|
|
|
(begin-for-syntax
|
|
|
|
(define (parse-template t)
|
|
(let-values ([(_const? drivers pre-guide) (parse-t t 0 #f)])
|
|
(define (set->env drivers)
|
|
(for/hash ([pvar (in-set drivers)]
|
|
[n (in-naturals 1)])
|
|
(values pvar n)))
|
|
(define main-env (set->env drivers))
|
|
(define (loop g loop-env)
|
|
(define (get-index x)
|
|
(let ([loop-index (hash-ref loop-env x #f)])
|
|
(if loop-index
|
|
(- loop-index)
|
|
(hash-ref main-env x))))
|
|
(match g
|
|
['_ '_]
|
|
[(cons g1 g2) (cons (loop g1 loop-env) (loop g2 loop-env))]
|
|
[(? syntax-pattern-variable? pvar) (get-index pvar)]
|
|
[(dots head hdrivers nesting tail)
|
|
(cond [(and (= nesting 1)
|
|
(= (set-count hdrivers) 1)
|
|
(not (head-guide? head)))
|
|
(let* ([pvar (for/first ([pvar (in-set hdrivers)]) pvar)]
|
|
[sub-loop-env (hash pvar 0)])
|
|
(sdots (loop head sub-loop-env)
|
|
(get-index pvar)
|
|
(loop tail loop-env)))]
|
|
[else
|
|
(let* ([sub-loop-env (set->env hdrivers)]
|
|
[sub-loop-vector (index-hash->vector sub-loop-env get-index)])
|
|
(dots (loop head sub-loop-env)
|
|
sub-loop-vector
|
|
nesting
|
|
(loop tail loop-env)))])]
|
|
[(app head tail)
|
|
(app (loop head loop-env) (loop tail loop-env))]
|
|
[(escaped g1)
|
|
(escaped (loop g1 loop-env))]
|
|
[(orelse g1 drivers1 g2)
|
|
(orelse (loop g1 loop-env)
|
|
(for/vector ([pvar (in-set drivers1)])
|
|
(get-index pvar))
|
|
(loop g2 loop-env))]
|
|
[(metafun mf g1)
|
|
(metafun (get-index mf)
|
|
(loop g1 loop-env))]
|
|
[(stxvector g1)
|
|
(stxvector (loop g1 loop-env))]
|
|
[(stxstruct g1)
|
|
(stxstruct (loop g1 loop-env))]
|
|
[(? box?)
|
|
(box (loop (unbox g) loop-env))]
|
|
[(app-opt g1 drivers1)
|
|
(app-opt (loop g1 loop-env)
|
|
(for/vector ([pvar (in-set drivers1)])
|
|
(get-index pvar)))]
|
|
[(splice g1)
|
|
(splice (loop g1 loop-env))]
|
|
[else (error 'template "internal error: bad pre-guide: ~e" g)]))
|
|
(define guide (loop pre-guide #hash()))
|
|
(values guide
|
|
(index-hash->vector main-env))))
|
|
|
|
;; ----------------------------------------
|
|
|
|
(define (parse-t t depth esc?)
|
|
(syntax-case t (?? ?@)
|
|
[id
|
|
(identifier? #'id)
|
|
(cond [(and (not esc?)
|
|
(or (free-identifier=? #'id (quote-syntax ...))
|
|
(free-identifier=? #'id (quote-syntax ??))
|
|
(free-identifier=? #'id (quote-syntax ?@))))
|
|
(wrong-syntax #'id "illegal use")]
|
|
[else
|
|
(let ([pvar (lookup #'id depth)])
|
|
(cond [(syntax-pattern-variable? pvar)
|
|
(values #f (set pvar) pvar)]
|
|
[(template-metafunction? pvar)
|
|
(wrong-syntax t "illegal use of syntax metafunction")]
|
|
[else (values #t (set) '_)]))])]
|
|
[atom
|
|
(atom? (syntax-e #'atom))
|
|
(values #t (set) '_)]
|
|
[(mf . template)
|
|
(and (not esc?)
|
|
(identifier? #'mf)
|
|
(template-metafunction? (lookup #'mf #f)))
|
|
(let-values ([(mf) (lookup #'mf #f)]
|
|
[(const? drivers guide) (parse-t #'template depth esc?)])
|
|
(values #f
|
|
(set-union (set mf) drivers)
|
|
(metafun mf guide)))]
|
|
[(DOTS template)
|
|
(and (not esc?)
|
|
(identifier? #'DOTS) (free-identifier=? #'DOTS (quote-syntax ...)))
|
|
(let-values ([(const? drivers guide) (parse-t #'template depth #t)])
|
|
(values #f drivers (escaped guide)))]
|
|
[(?? t1 t2)
|
|
(not esc?)
|
|
(let-values ([(const1? drivers1 guide1) (parse-t #'t1 depth esc?)]
|
|
[(const2? drivers2 guide2) (parse-t #'t2 depth esc?)])
|
|
(values #f
|
|
(set-union drivers1 drivers2)
|
|
(orelse guide1 (set-filter drivers1 syntax-pattern-variable?) guide2)))]
|
|
[(head DOTS . tail)
|
|
(and (not esc?)
|
|
(identifier? #'DOTS) (free-identifier=? #'DOTS (quote-syntax ...)))
|
|
(let-values ([(nesting tail)
|
|
(let loop ([nesting 1] [tail #'tail])
|
|
(syntax-case tail ()
|
|
[(DOTS . tail)
|
|
(and (identifier? #'DOTS) (free-identifier=? #'DOTS (quote-syntax ...)))
|
|
(loop (add1 nesting) #'tail)]
|
|
[else (values nesting tail)]))])
|
|
(let-values ([(hconst? hdrivers _hsplice? hguide) (parse-h #'head (+ depth nesting) esc?)]
|
|
[(tconst? tdrivers tguide) (parse-t tail depth esc?)])
|
|
(unless (positive? (set-count hdrivers))
|
|
(wrong-syntax #'head "no pattern variables in term before ellipsis"))
|
|
(values #f
|
|
(set-union hdrivers tdrivers)
|
|
(dots hguide (set-filter hdrivers pvar/depth>0?) nesting tguide))))]
|
|
[(head . tail)
|
|
(let-values ([(hconst? hdrivers hsplice? hguide) (parse-h #'head depth esc?)]
|
|
[(tconst? tdrivers tguide) (parse-t #'tail depth esc?)])
|
|
(let ([const? (and hconst? tconst?)])
|
|
(values const?
|
|
(set-union hdrivers tdrivers)
|
|
(cond [const? '_]
|
|
[hsplice? (app hguide tguide)]
|
|
[else (cons hguide tguide)]))))]
|
|
[vec
|
|
(vector? (syntax-e #'vec))
|
|
(let-values ([(const? drivers guide) (parse-t (vector->list (syntax-e #'vec)) depth esc?)])
|
|
(values const? drivers (if const? '_ (stxvector guide))))]
|
|
[pstruct
|
|
(prefab-struct-key (syntax-e #'pstruct))
|
|
(let-values ([(const? drivers guide) (parse-t (struct->list (syntax-e #'pstruct)) depth esc?)])
|
|
(values const? drivers (if const? '_ (stxstruct guide))))]
|
|
[#&template
|
|
(let-values ([(const? drivers guide) (parse-t #'template depth esc?)])
|
|
(values const? drivers (if const? '_ (box guide))))]
|
|
[_ (wrong-syntax t "bad pattern")]))
|
|
|
|
(define (parse-h h depth esc?)
|
|
(syntax-case h (?? ?@)
|
|
[(?? t)
|
|
(not esc?)
|
|
(let-values ([(const? drivers guide) (parse-t #'t depth esc?)])
|
|
(values #f drivers #t (app-opt guide (set-filter drivers syntax-pattern-variable?))))]
|
|
[(?@ . t)
|
|
(not esc?)
|
|
(let-values ([(const? drivers guide) (parse-t #'t depth esc?)])
|
|
(values #f drivers #t (splice guide)))]
|
|
[t
|
|
(let-values ([(const? drivers guide) (parse-t #'t depth esc?)])
|
|
(values const? drivers #f guide))]))
|
|
|
|
(define (atom? x)
|
|
(or (null? x)
|
|
(number? x)
|
|
(boolean? x)
|
|
(string? x)
|
|
(bytes? x)
|
|
(keyword? x)
|
|
(regexp? x)
|
|
(char? x)))
|
|
|
|
;; Note: always creates equal?-based set.
|
|
(define (set-filter s pred?)
|
|
(for/set ([el (in-set s)] #:when (pred? el)) el))
|
|
|
|
(define (lookup id depth)
|
|
(let ([v (syntax-local-value id (lambda () #f))])
|
|
(cond [(syntax-pattern-variable? v)
|
|
(unless (or (not depth)
|
|
(= (syntax-mapping-depth v) depth)
|
|
(= (syntax-mapping-depth v) 0))
|
|
(wrong-syntax id
|
|
"pattern variable used at wrong ellipsis depth (expected ~s, used at ~s)"
|
|
(syntax-mapping-depth v)
|
|
depth))
|
|
v]
|
|
[(template-metafunction? v)
|
|
v]
|
|
[else
|
|
;; id is a literal; check that for all x s.t. id = x.y, x is not a pattern variable
|
|
(for ([pfx (in-list (dotted-prefixes id))])
|
|
(when (syntax-pattern-variable? (syntax-local-value pfx (lambda () #f)))
|
|
(wrong-syntax id "undefined nested attribute of attribute `~a'" (syntax-e pfx))))
|
|
#f])))
|
|
|
|
(define (dotted-prefixes id)
|
|
(let* ([id-string (symbol->string (syntax-e id))]
|
|
[dot-locations (map car (regexp-match-positions* #rx"\\.[^.]" id-string))])
|
|
(for/list ([loc (in-list dot-locations)])
|
|
(datum->syntax id (string->symbol (substring id-string 0 loc))))))
|
|
|
|
(define (index-hash->vector hash [f values])
|
|
(let ([vec (make-vector (hash-count hash))])
|
|
(for ([(value index) (in-hash hash)])
|
|
(vector-set! vec (sub1 index) (f value)))
|
|
vec))
|
|
|
|
(define (pvar/depth>0? x)
|
|
(and (syntax-pattern-variable? x)
|
|
(positive? (syntax-mapping-depth x))))
|
|
|
|
)
|
|
|
|
;; ============================================================
|
|
|
|
(define (substitute stx g main-env)
|
|
(define (get index lenv)
|
|
(cond [(positive? index)
|
|
(vector-ref main-env (sub1 index))]
|
|
[(negative? index)
|
|
(vector-ref lenv (- -1 index))]
|
|
[(zero? index) lenv]))
|
|
(define (loop stx g lenv)
|
|
(match g
|
|
['_ stx]
|
|
[(cons g1 g2)
|
|
(restx stx (cons (loop (stx-car stx) g1 lenv) (loop (stx-cdr stx) g2 lenv)))]
|
|
[(? exact-integer? index)
|
|
(let ([v (get index lenv)])
|
|
(if (syntax? v)
|
|
v
|
|
(error/not-stx stx v)))]
|
|
[(sdots ghead loop-var gtail)
|
|
(let ([lenv* (get loop-var lenv)])
|
|
(unless lenv* (error 'template "pattern variable used in ellipsis pattern is not defined"))
|
|
(restx stx
|
|
(if (equal? ghead '0) ;; pattern was just (pvar ... . T)
|
|
(append lenv* (loop (stx-cddr stx) gtail lenv))
|
|
(let ([head-stx (stx-car stx)])
|
|
(let dotsloop ([lenv* lenv*])
|
|
(if (null? lenv*)
|
|
(loop (stx-cddr stx) gtail lenv)
|
|
(cons (loop head-stx ghead (car lenv*))
|
|
(dotsloop (cdr lenv*)))))))))]
|
|
[(dots ghead henv nesting gtail)
|
|
(define head-stx (stx-car stx))
|
|
(define (nestloop lenv* nesting)
|
|
(cond [(zero? nesting)
|
|
(loop-h head-stx ghead lenv*)]
|
|
[else
|
|
(for ([v (in-vector lenv*)])
|
|
(unless v (error 'template "pattern variable used in ellipsis pattern is not defined")))
|
|
(let ([len0 (length (vector-ref lenv* 0))])
|
|
(for ([v (in-vector lenv*)])
|
|
(unless (= len0 (length v))
|
|
(raise-syntax-error 'template
|
|
"incomplatible ellipsis match counts for template"
|
|
stx)))
|
|
(let dotsloop ([len0 len0] [lenv* lenv*])
|
|
(if (zero? len0)
|
|
null
|
|
(let ([lenv** (vector-map car lenv*)])
|
|
(cons (nestloop lenv** (sub1 nesting))
|
|
(dotsloop (sub1 len0) (vector-map! cdr lenv*)))))))]))
|
|
(let ([head-results ;; (listof^nesting (listof stx)) -- extra listof for loop-h
|
|
(nestloop (vector-map (lambda (index) (get index lenv)) henv) nesting)]
|
|
[tail-result (loop (stx-drop nesting (stx-cdr stx)) gtail lenv)])
|
|
(restx stx (deep-append head-results nesting tail-result)))]
|
|
[(app ghead gtail)
|
|
(restx stx (append (loop-h (stx-car stx) ghead lenv)
|
|
(loop (stx-cdr stx) gtail lenv)))]
|
|
[(escaped g1)
|
|
(loop (stx-cadr stx) g1 lenv)]
|
|
[(orelse g1 drivers1 g2)
|
|
(if (for/and ([index (in-vector drivers1)]) (get index lenv))
|
|
(loop (stx-cadr stx) g1 lenv)
|
|
(loop (stx-caddr stx) g2 lenv))]
|
|
[(metafun index g1)
|
|
(let ([v (restx stx (cons (stx-car stx) (loop (stx-cdr stx) g1 lenv)))]
|
|
[mark (make-syntax-introducer)]
|
|
[old-mark (current-template-metafunction-introducer)]
|
|
[mf (get index lenv)])
|
|
(parameterize ((current-template-metafunction-introducer mark))
|
|
(let ([r (mf (mark (old-mark v)))])
|
|
(unless (syntax? r)
|
|
(raise-syntax-error 'template "result of metafunction was not syntax" stx))
|
|
(restx stx (old-mark (mark r))))))]
|
|
[(stxvector g1)
|
|
(restx stx (list->vector (loop (vector->list (syntax-e stx)) g1 lenv)))]
|
|
[(stxstruct g1)
|
|
(let ([s (syntax-e stx)])
|
|
(restx stx (apply make-prefab-struct
|
|
(prefab-struct-key s)
|
|
(loop (struct->list s) g1 lenv))))]
|
|
[(box g1)
|
|
(restx stx (box (loop (unbox (syntax-e stx)) g1 lenv)))]))
|
|
(define (loop-h stx hg lenv)
|
|
(match hg
|
|
[(app-opt g1 drivers1)
|
|
(if (for/and ([index (in-vector drivers1)]) (get index lenv))
|
|
(list (loop (stx-cadr stx) g1 lenv))
|
|
null)]
|
|
[(splice g1)
|
|
(let* ([v (loop (stx-cdr stx) g1 lenv)]
|
|
[v* (stx->list v)])
|
|
(unless v*
|
|
(raise-syntax-error 'template
|
|
"splicing template did not produce a syntax list"
|
|
stx))
|
|
v*)]
|
|
[else (list (loop stx hg lenv))]))
|
|
(loop stx g #f))
|
|
|
|
(define current-template-metafunction-introducer
|
|
(make-parameter
|
|
(lambda (stx)
|
|
(if (syntax-transforming?)
|
|
(syntax-local-introduce stx)
|
|
stx))))
|
|
|
|
(define (stx-cadr x) (stx-car (stx-cdr x)))
|
|
(define (stx-cddr x) (stx-cdr (stx-cdr x)))
|
|
(define (stx-caddr x) (stx-car (stx-cdr (stx-cdr x))))
|
|
|
|
(define (stx-drop n x)
|
|
(cond [(zero? n) x]
|
|
[else (stx-drop (sub1 n) (stx-cdr x))]))
|
|
|
|
(define (restx basis val)
|
|
(if (syntax? basis)
|
|
(datum->syntax basis val basis basis)
|
|
val))
|
|
|
|
;; deep-append : (listof^(nesting+1) A) nat (listof A) -> (listof A)
|
|
;; (Actually, in practice onto is stx, so this is an improper append.)
|
|
(define (deep-append lst nesting onto)
|
|
(cond [(null? lst) onto]
|
|
[(zero? nesting) (append lst onto)]
|
|
[else (deep-append (car lst) (sub1 nesting)
|
|
(deep-append (cdr lst) nesting onto))]))
|
|
|
|
(define (error/not-stx stx val)
|
|
(raise-syntax-error 'template "pattern variable is not syntax-valued" stx))
|