racket/collects/syntax/parse/private/residual.rkt
2012-12-03 19:28:12 -05:00

227 lines
7.8 KiB
Racket

#lang racket/base
(require (for-syntax racket/base)
racket/stxparam
racket/lazy-require)
;; ============================================================
;; Compile-time
(require (for-syntax racket/private/sc
syntax/parse/private/residual-ct))
(provide (for-syntax (all-from-out syntax/parse/private/residual-ct)))
(begin-for-syntax
;; == from runtime.rkt
(provide make-attribute-mapping
attribute-mapping?
attribute-mapping-var
attribute-mapping-name
attribute-mapping-depth
attribute-mapping-syntax?)
(define-struct attribute-mapping (var name depth syntax?)
#:omit-define-syntaxes
#:property prop:procedure
(lambda (self stx)
(if (attribute-mapping-syntax? self)
#`(#%expression #,(attribute-mapping-var self))
(let ([source-name
(or (let loop ([p (syntax-property stx 'disappeared-use)])
(cond [(identifier? p) p]
[(pair? p) (or (loop (car p)) (loop (cdr p)))]
[else #f]))
(attribute-mapping-name self))])
#`(let ([value #,(attribute-mapping-var self)])
(check-attr-value-is-syntax '#,(attribute-mapping-depth self)
value
(quote-syntax #,source-name))
value)))))
)
;; ============================================================
;; Run-time
(require "runtime-progress.rkt"
syntax/stx)
(provide (all-from-out "runtime-progress.rkt")
this-syntax
this-role
this-context-syntax
attribute
attribute-binding
stx-list-take
stx-list-drop/cx
check-list^depth*
check-literal*
begin-for-syntax/once
name->too-few/once
name->too-few
name->too-many
syntax-patterns-fail)
;; == from runtime.rkt
;; this-syntax
;; Bound to syntax being matched inside of syntax class
(define-syntax-parameter this-syntax
(lambda (stx)
(raise-syntax-error #f "used out of context: not within a syntax class" stx)))
(define-syntax-parameter this-role
(lambda (stx)
(raise-syntax-error #f "used out of context: not within a syntax class" stx)))
;; this-context-syntax
;; Bound to (expression that extracts) context syntax (bottom frame in progress)
(define-syntax-parameter this-context-syntax
(lambda (stx)
(raise-syntax-error #f "used out of context: not within a syntax class" stx)))
(define-syntax (attribute stx)
(syntax-case stx ()
[(attribute name)
(identifier? #'name)
(let ([mapping (syntax-local-value #'name (lambda () #f))])
(unless (syntax-pattern-variable? mapping)
(raise-syntax-error #f "not bound as a pattern variable" stx #'name))
(let ([var (syntax-mapping-valvar mapping)])
(let ([attr (syntax-local-value var (lambda () #f))])
(unless (attribute-mapping? attr)
(raise-syntax-error #f "not bound as an attribute" stx #'name))
(syntax-property (attribute-mapping-var attr)
'disappeared-use
#'name))))]))
;; (attribute-binding id)
;; mostly for debugging/testing
(define-syntax (attribute-binding stx)
(syntax-case stx ()
[(attribute-bound? name)
(identifier? #'name)
(let ([value (syntax-local-value #'name (lambda () #f))])
(if (syntax-pattern-variable? value)
(let ([value (syntax-local-value (syntax-mapping-valvar value) (lambda () #f))])
(if (attribute-mapping? value)
#`(quote #,(make-attr (attribute-mapping-name value)
(attribute-mapping-depth value)
(attribute-mapping-syntax? value)))
#'(quote #f)))
#'(quote #f)))]))
;; stx-list-take : stxish nat -> syntax
(define (stx-list-take stx n)
(datum->syntax #f
(let loop ([stx stx] [n n])
(if (zero? n)
null
(cons (stx-car stx)
(loop (stx-cdr stx) (sub1 n)))))))
;; stx-list-drop/cx : stxish stx nat -> (values stxish stx)
(define (stx-list-drop/cx x cx n)
(let loop ([x x] [cx cx] [n n])
(if (zero? n)
(values x
(if (syntax? x) x cx))
(loop (stx-cdr x)
(if (syntax? x) x cx)
(sub1 n)))))
;; check-attr-value-is-syntax : nat any id -> boolean
;; returns #t if value is a (listof^depth syntax)
;; used by attribute-mapping code above
(define (check-attr-value-is-syntax depth value source-id)
(define (check-syntax depth value)
(if (zero? depth)
(syntax? value)
(and (list? value)
(for/and ([part (in-list value)])
(check-syntax (sub1 depth) part)))))
(unless (check-syntax depth value)
(raise-syntax-error #f
(format "attribute is bound to non-syntax value: ~e" value)
source-id)))
;; check-list^depth* : symbol nat any -> list^depth
(define (check-list^depth* aname n0 v0)
(define (loop n v)
(when (positive? n)
(unless (list? v)
(raise-type-error aname (format "lists nested ~s deep" n0) v))
(for ([x (in-list v)]) (loop (sub1 n) x))))
(loop n0 v0)
v0)
;; check-literal* : id phase phase (listof phase) stx -> void
(define (check-literal* id used-phase mod-phase ok-phases/ct-rel ctx)
(unless (or (memv (and used-phase (- used-phase mod-phase))
ok-phases/ct-rel)
(identifier-binding id used-phase))
(raise-syntax-error
#f
(format "literal is unbound in phase ~a (phase ~a relative to the enclosing module)"
used-phase
(and used-phase (- used-phase mod-phase)))
ctx id)))
;; (begin-for-syntax/once expr/phase1 ...)
;; evaluates in pass 2 of module/intdefs expansion
(define-syntax (begin-for-syntax/once stx)
(syntax-case stx ()
[(bfs/o e ...)
(cond [(list? (syntax-local-context))
#`(define-values ()
(begin (begin-for-syntax/once e ...)
(values)))]
[else
#'(let-syntax ([m (lambda _ (begin e ...) #'(void))])
(m))])]))
;; == parse.rkt
(define (name->too-few/once name)
(and name (format "missing required occurrence of ~a" name)))
(define (name->too-few name)
(and name (format "too few occurrences of ~a" name)))
(define (name->too-many name)
(and name (format "too many occurrences of ~a" name)))
;; == parse.rkt
(lazy-require
["runtime-report.rkt"
(syntax-patterns-fail)])
;; == specialized ellipsis parser
;; returns (values 'ok attr-values) or (values 'fail failure)
(provide predicate-ellipsis-parser)
(define (predicate-ellipsis-parser x cx pr es pred? desc rl)
(let ([elems (stx->list x)])
(if (and elems (list? elems) (andmap pred? elems))
(values 'ok elems)
(let loop ([x x] [cx cx] [i 0])
(cond [(syntax? x)
(loop (syntax-e x) x i)]
[(pair? x)
(if (pred? (car x))
(loop (cdr x) cx (add1 i))
(let* ([pr (ps-add-cdr pr i)]
[pr (ps-add-car pr)]
[es (es-add-thing pr desc #t rl es)])
(values 'fail (failure pr es))))]
[else ;; not null, because stx->list failed
(let ([pr (ps-add-cdr pr i)]
#|
;; Don't extend es! That way we don't get spurious "expected ()"
;; that *should* have been cancelled out by ineffable pair failures.
|#)
(values 'fail (failure pr es)))])))))