racket/collects/scheme/splicing.ss

235 lines
9.4 KiB
Scheme

#lang scheme/base
(require (for-syntax scheme/base
syntax/kerncase)
"stxparam.ss"
"private/stxparam.ss"
"private/local.ss")
(provide splicing-let-syntax
splicing-let-syntaxes
splicing-letrec-syntax
splicing-letrec-syntaxes
splicing-let
splicing-let-values
splicing-letrec
splicing-letrec-values
splicing-letrec-syntaxes+values
splicing-local
splicing-syntax-parameterize)
(define-for-syntax ((check-id stx) id-stx)
(unless (identifier? id-stx)
(raise-syntax-error #f "expected an identifier" stx id-stx))
(list id-stx))
(define-for-syntax ((check-ids stx) ids-stx)
(let ([ids (syntax->list ids-stx)])
(unless ids
(raise-syntax-error
#f
"expected a parenthesized sequence of identifiers"
stx
ids-stx))
(for-each (check-id stx) ids)
ids))
(define-for-syntax (check-dup-binding stx idss)
(let ([dup-id (check-duplicate-identifier (apply append idss))])
(when dup-id
(raise-syntax-error #f "duplicate binding" stx dup-id))))
(define-for-syntax (do-let-syntax stx rec? multi? let-id def-id need-top-decl?)
(syntax-case stx ()
[(_ ([ids expr] ...) body ...)
(let ([all-ids (map ((if multi? check-ids check-id) stx)
(syntax->list #'(ids ...)))])
(check-dup-binding stx all-ids)
(if (eq? 'expression (syntax-local-context))
(with-syntax ([LET let-id])
(syntax/loc stx
(LET ([ids expr] ...)
(#%expression body)
...)))
(let ([def-ctx (syntax-local-make-definition-context)]
[ctx (list (gensym 'intdef))])
(syntax-local-bind-syntaxes (apply append all-ids) #f def-ctx)
(internal-definition-context-seal def-ctx)
(let* ([add-context
(lambda (expr)
(let ([q (local-expand #`(quote #,expr)
ctx
(list #'quote)
def-ctx)])
(syntax-case q ()
[(_ expr) #'expr])))])
(with-syntax ([((id ...) ...)
(map (lambda (ids)
(map add-context ids))
all-ids)]
[(expr ...)
(let ([exprs (syntax->list #'(expr ...))])
(if rec?
(map add-context exprs)
exprs))]
[(body ...)
(map add-context (syntax->list #'(body ...)))]
[DEF def-id])
(with-syntax ([(top-decl ...)
(if (and need-top-decl? (equal? 'top-level (syntax-local-context)))
#'((define-syntaxes (id ... ...) (values)))
null)])
#'(begin
top-decl ...
(DEF (id ...) expr)
...
body ...)))))))]))
(define-syntax (splicing-let-syntax stx)
(do-let-syntax stx #f #f #'let-syntax #'define-syntaxes #f))
(define-syntax (splicing-let-syntaxes stx)
(do-let-syntax stx #f #t #'let-syntaxes #'define-syntaxes #f))
(define-syntax (splicing-letrec-syntax stx)
(do-let-syntax stx #t #f #'letrec-syntax #'define-syntaxes #f))
(define-syntax (splicing-letrec-syntaxes stx)
(do-let-syntax stx #t #t #'letrec-syntaxes #'define-syntaxes #f))
(define-syntax (splicing-let stx)
(do-let-syntax stx #f #f #'let #'define-values #f))
(define-syntax (splicing-let-values stx)
(do-let-syntax stx #f #t #'let-values #'define-values #f))
(define-syntax (splicing-letrec stx)
(do-let-syntax stx #t #f #'letrec #'define-values #t))
(define-syntax (splicing-letrec-values stx)
(do-let-syntax stx #t #t #'letrec-values #'define-values #t))
;; ----------------------------------------
(define-syntax (splicing-letrec-syntaxes+values stx)
(syntax-case stx ()
[(_ ([sids sexpr] ...) ([vids vexpr] ...) body ...)
(let* ([all-sids (map (check-ids stx)
(syntax->list #'(sids ...)))]
[all-vids (map (check-ids stx)
(syntax->list #'(vids ...)))]
[all-ids (append all-sids all-vids)])
(check-dup-binding stx all-ids)
(if (eq? 'expression (syntax-local-context))
(syntax/loc stx
(letrec-syntaxes+values ([sids sexpr] ...) ([vids vexpr] ...)
(#%expression body) ...))
(let ([def-ctx (syntax-local-make-definition-context)]
[ctx (list (gensym 'intdef))])
(syntax-local-bind-syntaxes (apply append all-ids) #f def-ctx)
(internal-definition-context-seal def-ctx)
(let* ([add-context
(lambda (expr)
(let ([q (local-expand #`(quote #,expr)
ctx
(list #'quote)
def-ctx)])
(syntax-case q ()
[(_ expr) #'expr])))]
[add-context-to-idss
(lambda (idss)
(map add-context idss))])
(with-syntax ([((sid ...) ...)
(map add-context-to-idss all-sids)]
[((vid ...) ...)
(map add-context-to-idss all-vids)]
[(sexpr ...)
(map add-context (syntax->list #'(sexpr ...)))]
[(vexpr ...)
(map add-context (syntax->list #'(vexpr ...)))]
[(body ...)
(map add-context (syntax->list #'(body ...)))])
(with-syntax ([top-decl
(if (equal? 'top-level (syntax-local-context))
#'(define-syntaxes (vid ... ...) (values))
#'(begin))])
(syntax/loc stx
(begin
top-decl
(define-syntaxes (sid ...) sexpr) ...
(define-values (vid ...) vexpr) ...
body ...))))))))]))
(define-syntax (splicing-local stx)
(do-local stx #'splicing-letrec-syntaxes+values))
;; ----------------------------------------
(define-syntax (splicing-syntax-parameterize stx)
(if (eq? 'expression (syntax-local-context))
;; Splicing is no help in an expression context:
(do-syntax-parameterize stx #'let-syntaxes #f)
;; Let `syntax-parameterize' check syntax, then continue
(do-syntax-parameterize stx #'ssp-let-syntaxes #t)))
(define-syntax (ssp-let-syntaxes stx)
(syntax-case stx ()
[(_ ([(id) rhs] ...) body ...)
(with-syntax ([(splicing-temp ...) (generate-temporaries #'(id ...))])
#'(begin
;; Evaluate each RHS only once:
(define-syntax splicing-temp rhs) ...
;; Partially expand `body' to push down `let-syntax':
(expand-ssp-body (id ...) (splicing-temp ...) body)
...))]))
(define-syntax (expand-ssp-body stx)
(syntax-case stx ()
[(_ (sp-id ...) (temp-id ...) body)
(let ([body (local-expand #'(letrec-syntaxes/trans ([(sp-id) (syntax-local-value (quote-syntax temp-id))]
...)
(force-expand body))
(syntax-local-context)
null ;; `force-expand' actually determines stopping places
#f)])
;; Extract expanded body out of `body':
(syntax-case body (quote)
[(ls _ _ (quote body))
(let ([body #'body])
(syntax-case body (begin define-values define-syntaxes define-for-syntaxes)
[(begin expr ...)
(syntax/loc body
(begin (expand-ssp-body (sp-id ...) (temp-id ...) expr) ...))]
[(define-values (id ...) rhs)
(syntax/loc body
(define-values (id ...)
(letrec-syntaxes ([(sp-id) (syntax-local-value (quote-syntax temp-id))] ...)
rhs)))]
[(define-syntaxes . _) body]
[(define-for-syntaxes . _) body]
[expr (syntax/loc body
(letrec-syntaxes ([(sp-id) (syntax-local-value (quote-syntax temp-id))] ...)
expr))]))]))]))
(define-syntax (letrec-syntaxes/trans stx)
(syntax-case stx ()
[(_ bindings body)
(syntax-property
#'(letrec-syntaxes bindings body)
'certify-mode
'transparent)]))
(define-syntax (force-expand stx)
(syntax-case stx ()
[(_ stx)
;; Expand `stx' to reveal type of form, and then preserve it via
;; `quote':
(syntax-property
#`(quote #,(local-expand #'stx
'module
(kernel-form-identifier-list)
#f))
'certify-mode
'transparent)]))