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beautiful-racket/beautiful-racket-lib/br/syntax.rkt

146 lines
5.5 KiB
Racket

#lang racket/base
(require (for-syntax
racket/base
br/private/generate-literals)
racket/list
racket/match
racket/syntax
racket/format
syntax/stx
syntax/strip-context
syntax/parse
br/define
br/private/syntax-flatten)
(provide (all-defined-out)
syntax-flatten
stx-map
strip-context ;; under both names
(rename-out [strip-context strip-bindings]
[replace-context replace-bindings]
[stx-map syntax-map]
[syntax-flatten stx-flatten]
[prefix-id prefix-ids]
[suffix-id suffix-ids]
[infix-id infix-ids]))
(module+ test (require rackunit))
(define-macro-cases syntax-parse/easy
[(_ STX [PAT . BODY] ... [else . ELSEBODY])
(with-syntax ([(PAT ...) (map (λ (stx) (literalize-pat stx #'~literal)) (syntax->list #'(PAT ...)))])
#'(syntax-parse (syntax-case STX () [any #'any])
[PAT . BODY] ... [else . ELSEBODY]))])
(define-macro-cases pattern-case
[(_ EXPR ... [else . ELSEBODY]) #'(syntax-parse/easy EXPR ...
[else . ELSEBODY])]
[(_ STX-ARG PAT+BODY ...)
#'(pattern-case STX-ARG
PAT+BODY ...
[else (raise-syntax-error 'pattern-case
(format "unable to match pattern for ~v" (syntax->datum STX-ARG)))])])
(module+ test
(define (pc stx)
(pattern-case stx
[(a 2ND c) #'2ND]
[(LEFT RIGHT) #'LEFT]
[(g) #'hooray]))
(check-equal? (syntax->datum (pc #'(a b c))) 'b)
(check-equal? (syntax->datum (pc #'(x y))) 'x)
(check-equal? (syntax->datum (pc #'(g))) 'hooray)
(check-exn exn:fail:syntax? (λ () (pc #'(f)))))
(define-macro (pattern-case-filter STX-ARG PAT+BODY ...)
#'(let* ([arg STX-ARG]
[stxs (or (and (syntax? arg) (syntax->list arg)) arg)])
(unless (and (list? stxs) (andmap syntax? stxs))
(raise-syntax-error 'pattern-case-filter
(format "~v cannot be made into a list of syntax objects" (syntax->datum arg))))
(for*/list ([stx (in-list stxs)]
[result (in-value (pattern-case stx PAT+BODY ... [else #f]))]
#:when result)
result)))
(module+ test
(define (pcf x)
(pattern-case-filter x
[(1ST 2ND 3RD) #'2ND]
[(LEFT RIGHT) #'LEFT]))
(check-equal? (map syntax-e (pcf #'((a b c) (x y) (f)))) '(b x)))
(define-macro-cases with-pattern
[(_ () . BODY) #'(begin . BODY)]
[(_ ([PAT0 STX0] PAT+STX ...) . BODY)
#'(syntax-parse/easy STX0
[PAT0 (with-pattern (PAT+STX ...) (let () (void) . BODY))]
[else (raise-syntax-error 'with-pattern
(format "unable to match pattern ~a" 'PAT0) STX0)])])
(module+ test
(check-equal? (syntax->datum (with-pattern ([foo 'foo])
#'zzz)) 'zzz)
(check-exn exn:fail:syntax? (λ () (with-pattern ([42 'foo])
#'zzz)))
(check-exn exn:fail:syntax? (λ () (with-pattern ([bar 'foo])
#'zzz)))
(check-equal? (syntax->datum (with-pattern ([(foo BAR) '(foo 42)])
#'BAR)) 42)
(check-exn exn:fail:syntax? (λ () (with-pattern ([(foo BAR) '(zam 42)])
#'BAR))))
(define-macro (format-string FMT ID0 ID ...)
#'(datum->syntax ID0 (format FMT (syntax->datum ID0) (syntax->datum ID) ...)))
(define (->unsyntax x) (if (syntax? x) (syntax->datum x) x))
(define (stx-join stxs)
(apply string-append (map (compose1 ~a ->unsyntax) stxs)))
(define (*fix-base loc-arg ctx-arg prefixes base-or-bases suffixes)
(define list-mode? (or (list? base-or-bases) (syntax->list base-or-bases)))
(define bases (if list-mode?
(or (syntax->list base-or-bases) base-or-bases)
(list base-or-bases)))
(define result (map (λ (base) (format-id (or ctx-arg base) "~a~a~a" (stx-join prefixes) (syntax-e base) (stx-join suffixes)
#:source loc-arg)) bases))
(if list-mode? result (car result)))
(define (prefix-id #:source [loc-arg #f] #:context [ctx-arg #f] . args)
((match-lambda
[(list prefixes ... base-or-bases)
(*fix-base loc-arg ctx-arg prefixes base-or-bases empty)]) args))
(define (infix-id #:source [loc-arg #f] #:context [ctx-arg #f] . args)
((match-lambda
[(list prefix base-or-bases suffixes ...)
(*fix-base loc-arg ctx-arg (list prefix) base-or-bases suffixes)]) args))
(define (suffix-id #:source [loc-arg #f] #:context [ctx-arg #f] . args)
((match-lambda
[(list base-or-bases suffixes ...)
(*fix-base loc-arg ctx-arg empty base-or-bases suffixes)]) args))
(module+ test
(define-check (check-stx-equal? stx1 stx2)
(define stxs (list stx1 stx2))
(apply equal? (map syntax->datum stxs)))
(check-stx-equal? (prefix-id "foo" "bar" #'id) #'foobarid)
(check-stx-equal? (infix-id "foo" #'id "bar" "zam") #'fooidbarzam)
(check-stx-equal? (suffix-id #'id "foo" "bar" "zam") #'idfoobarzam)
(for-each check-stx-equal? (suffix-id #'(this that) "@") (list #'this@ #'that@)))
(define (syntax-srcloc stx)
(srcloc (syntax-source stx)
(syntax-line stx)
(syntax-column stx)
(syntax-position stx)
(syntax-span stx)))