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#lang racket/base
(require racket/contract/base
syntax/srcloc
syntax/modcollapse
racket/syntax
syntax/location)
(provide/contract
[wrap-expr/c
(->* (syntax? syntax?)
(#:arg? any/c
#:positive (or/c syntax? string? module-path-index?
'from-macro 'use-site 'unknown)
#:negative (or/c syntax? string? module-path-index?
'from-macro 'use-site 'unknown)
#:name (or/c identifier? symbol? string? #f)
#:macro (or/c identifier? symbol? string? #f)
#:context (or/c syntax? #f)
#:phase exact-integer?)
syntax?)])
(module runtime racket/base
(require (for-syntax racket/base
syntax/free-vars)
racket/contract/base
racket/contract/combinator
(only-in racket/contract/private/base
make-apply-contract)
syntax/location)
(provide (all-from-out racket/base
syntax/location)
expr/contract
relative-source)
(define (macro-expr/c arg? expr-name ctc0)
(define ctc (coerce-contract 'wrap-expr/c ctc0))
(define proj (get/build-late-neg-projection ctc))
(make-contract
#:name (unquoted-printing-string
(format "macro ~a contract~a~a"
(if arg? "argument" "result")
(if expr-name " on " "")
(if expr-name expr-name "")))
#:first-order (contract-first-order ctc)
#:late-neg-projection
(λ (blame)
(define blame* (blame-add-context blame (format "~s" (contract-name ctc)) #:swap? arg?))
(proj blame*))
#:list-contract? (list-contract? ctc)))
(define (macro-dep-expr/c arg? expr-name)
(make-contract
#:name (unquoted-printing-string
(format "macro ~a contract~a~a"
(if arg? "argument" "result")
(if expr-name " on " "")
(if expr-name expr-name "")))
#:late-neg-projection
(lambda (blame)
(lambda (_f neg)
;; Note: specialized to _f = return-second-arg.
(lambda (c v)
(define (slow-path)
(define ctc (coerce-contract 'wrap-expr/c c))
(define proj (get/build-late-neg-projection ctc))
(define blame*
(blame-add-context blame (format "~s" (contract-name ctc)) #:swap? arg?))
((proj blame*) v neg))
(cond [(flat-contract? c)
(let ([c (if (procedure? c) c (coerce-contract 'wrap-expr/c c))])
(if (c v) v (slow-path)))]
[else (slow-path)]))))))
(define (return-second-arg c v) v)
(begin-for-syntax
(define (okay-to-lift? ee)
(and (identifier? ee) (not (local-free-vars? ee))))
(define (self-module-path-index? mpi)
(define-values (rel base) (module-path-index-split mpi))
(and (eq? rel #f) (eq? (module-path-index-submodule mpi) #f)))
(define (local-free-vars? ee)
(for/or ([fv (in-list (free-vars ee #:module-bound? #t))])
(define b (identifier-binding fv))
(cond [(list? b) (self-module-path-index? (car b))]
[else #t]))))
(define-syntax (expr/contract stx)
(cond
[(eq? (syntax-local-context) 'expression)
(syntax-case stx ()
[(_ val-expr ctc-expr arg? expr-name [mac-arg ...])
(let ([ctc-ee (local-expand #'ctc-expr 'expression null)])
(cond [(okay-to-lift? ctc-ee)
#`(#,(syntax-local-lift-expression
#`(make-apply-contract
(macro-expr/c arg? expr-name #,ctc-ee)
mac-arg ...))
val-expr)]
[else
#`(#,(syntax-local-lift-expression
#`((make-apply-contract
(macro-dep-expr/c arg? expr-name)
mac-arg ...)
return-second-arg))
#,ctc-ee
val-expr)]))])]
[else #`(#%expression #,stx)]))
(define (relative-source base-mpi rel-mod-path)
(define r
(resolved-module-path-name
(module-path-index-resolve
(module-path-index-join rel-mod-path base-mpi))))
(cond [(pair? r)
(cons 'submod r)]
[(symbol? r)
(list 'quote r)]
[else r])))
;; Allow phase shift of 0 or 1 without needing to lift requires
(require (for-template (submod "." runtime))
;; for phase +1 uses, only need to instantiate, since we’ll shift
(only-in (submod "." runtime)))
(define (wrap-expr/c ctc-expr expr
#:arg? [arg? #t]
#:positive [pos-source 'from-macro]
#:negative [neg-source 'use-site]
#:name [expr-name #f]
#:macro [macro-name #f]
#:context [ctx (current-syntax-context)]
#:phase [phase (syntax-local-phase-level)])
(let* ([pos-source-expr
(get-source-expr pos-source
(if (identifier? macro-name) macro-name ctx))]
[neg-source-expr
(get-source-expr neg-source
(if (identifier? macro-name) macro-name ctx))]
[expr-name
(if (identifier? expr-name)
(syntax-e expr-name)
expr-name)]
[macro-name
(cond [(identifier? macro-name) (syntax-e macro-name)]
[(or (string? macro-name) (symbol? macro-name)) macro-name]
[(syntax? ctx)
(syntax-case ctx ()
[(x . _) (identifier? #'x) (syntax-e #'x)]
[x (identifier? #'x) (syntax-e #'x)]
[_ '?])]
[else '?])]
[introduce (make-syntax-introducer)]
[phase-shift (- phase (syntax-local-phase-level))]
[shift+introduce (lambda (stx) (introduce (syntax-shift-phase-level stx phase-shift)))]
[unshift+introduce (lambda (stx) (introduce (syntax-shift-phase-level stx (- phase-shift))))]
[expr+ctc (shift+introduce
#`(expr/contract #,(unshift+introduce expr) #,(unshift+introduce ctc-expr)
'#,(and arg? #t) '#,expr-name
[#,pos-source-expr
#,neg-source-expr
'#,macro-name
(quote-syntax #,expr)
#f]))])
(cond
;; no need to lift for common phases, since we explicitly require them in this module
[(memq phase-shift '(0 1))
expr+ctc]
[else
(unless (syntax-transforming?)
(raise-arguments-error 'wrap-expr/c "not currently expanding"))
(define phased-require-spec
(introduce (datum->syntax #'here `(for-meta ,phase-shift ,(quote-module-path runtime)))))
(syntax-local-introduce (syntax-local-lift-require (syntax-local-introduce phased-require-spec)
(syntax-local-introduce expr+ctc)))])))
(define (get-source-expr source ctx)
(cond [(eq? source 'use-site)
#'(quote-module-path)]
[(eq? source 'unknown)
#'(quote "unknown")]
[(eq? source 'from-macro)
(get-source-expr (extract-source ctx) #f)]
[(string? source) #`(quote #,source)]
[(syntax? source) #`(quote #,(source-location->string source))]
[(module-path-index? source)
;; FIXME: This assumes that if source is relative, it is relative to
;; the current self-index (the module currently being compiled). That
;; should usually be the case, but it's not necessarily true.
(define collapsed (collapse-module-path-index source))
(cond [(eq? collapsed #f)
#'(quote-module-path)]
[(relative-module-path? collapsed)
#`(relative-source (variable-reference->module-path-index
(#%variable-reference))
'#,collapsed)]
[else #`(quote #,collapsed)])]))
(define (relative-module-path? mp)
(or (string? mp) (path? mp)
(and (pair? mp) (eq? (car mp) 'submod)
(let ([base (cadr mp)]) (or (string? base) (path? base))))))
;; extract-source : (U Syntax #f) -> (U ModulePathIndex 'use-site 'unknown)
(define (extract-source stx)
(let ([id (syntax-case stx ()
[(x . _) (identifier? #'x) #'x]
[x (identifier? #'x) #'x]
[_ #f])])
(if id
(let ([b (identifier-binding id)])
(cond [(list? b) (car b)] ;; module-path-index
[else 'use-site]))
'unknown)))
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