racket/collects/syntax/private/util/expand.rkt
2011-09-27 19:28:44 -06:00

89 lines
3.9 KiB
Racket

#lang racket/base
(require syntax/kerncase
syntax/stx)
(provide head-local-expand-and-categorize-syntaxes
categorize-expanded-syntaxes
head-local-expand-syntaxes)
;; head-local-expand-syntaxes : syntax boolean boolean -> stxs ^ 6
;; Setting allow-def-after-expr? allows def/expr interleaving.
(define (head-local-expand-and-categorize-syntaxes x allow-def-after-expr?)
(define estxs (head-local-expand-syntaxes x allow-def-after-expr?))
(define-values (defs vdefs sdefs exprs)
(categorize-expanded-syntaxes estxs))
(values estxs estxs defs vdefs sdefs exprs))
;; categorize-expanded-syntaxes : (listof stx) -> stxs ^ 4
;; Split head-expanded stxs into
;; definitions, values-definitions, syntaxes-definitions, exprs
;; (definitions include both values-definitions and syntaxes-definitions.)
(define (categorize-expanded-syntaxes estxs0)
(let loop ([estxs estxs0] [defs null] [vdefs null] [sdefs null] [exprs null])
(cond [(pair? estxs)
(let ([ee (car estxs)])
(syntax-case ee (begin define-values define-syntaxes)
[(define-values . _)
(loop (cdr estxs)
(cons ee defs)
(cons ee vdefs)
sdefs
exprs)]
[(define-syntaxes (var ...) rhs)
(loop (cdr estxs)
(cons ee defs)
vdefs
(cons ee sdefs)
exprs)]
[_
(loop (cdr estxs)
defs
vdefs
sdefs
(cons ee exprs))]))]
[(null? estxs)
(values (reverse defs)
(reverse vdefs)
(reverse sdefs)
(reverse exprs))])))
;; head-local-expand-syntaxes : syntax boolean -> (listof syntax)
(define (head-local-expand-syntaxes x allow-def-after-expr?)
(let ([intdef (syntax-local-make-definition-context)]
[ctx '(block)])
(let loop ([x x] [ex null] [expr? #f])
(cond [(stx-pair? x)
(let ([ee (local-expand (stx-car x)
ctx
(kernel-form-identifier-list)
intdef)])
(syntax-case ee (begin define-values define-syntaxes)
[(begin e ...)
(loop (append (syntax->list #'(e ...)) (stx-cdr x)) ex expr?)]
[(begin . _)
(raise-syntax-error #f "bad begin form" ee)]
[(define-values (var ...) rhs)
(andmap identifier? (syntax->list #'(var ...)))
(begin
(when (and expr? (not allow-def-after-expr?))
(raise-syntax-error #f "definition after expression" ee))
(syntax-local-bind-syntaxes (syntax->list #'(var ...)) #f intdef)
(loop (stx-cdr x) (cons ee ex) expr?))]
[(define-values . _)
(raise-syntax-error #f "bad define-values form" ee)]
[(define-syntaxes (var ...) rhs)
(andmap identifier? (syntax->list #'(var ...)))
(begin
(when (and expr? (not allow-def-after-expr?))
(raise-syntax-error #f "definition after expression" ee))
(syntax-local-bind-syntaxes (syntax->list #'(var ...))
#'rhs
intdef)
(loop (stx-cdr x) (cons ee ex) expr?))]
[(define-syntaxes . _)
(raise-syntax-error #f "bad define-syntaxes form" ee)]
[_
(loop (stx-cdr x) (cons ee ex) #t)]))]
[(stx-null? x)
(internal-definition-context-seal intdef)
(reverse ex)]))))