f2dc2027f6
in the original GitHub fork: https://github.com/ntoronto/racket Some things about this are known to be broken (most egregious is that the array tests DO NOT RUN because of a problem in typed/rackunit), about half has no coverage in the tests, and half has no documentation. Fixes and docs are coming. This is committed now to allow others to find errors and inconsistency in the things that appear to be working, and to give the author a (rather incomplete) sense of closure.
45 lines
1.4 KiB
Racket
45 lines
1.4 KiB
Racket
#lang racket/base
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(require (for-syntax racket/base))
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(provide array/syntax)
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(define-for-syntax (square-bracket? e-stx)
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(eq? #\[ (syntax-property e-stx 'paren-shape)))
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(define-for-syntax (syntax-list-shape e-stx)
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(define lst (syntax->list e-stx))
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(cond [(or (not lst) (not (square-bracket? e-stx))) null]
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[(null? lst) (list 0)]
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[else
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(define d (length lst))
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(define ds (syntax-list-shape (car lst)))
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(if ds
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(let loop ([lst (cdr lst)])
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(cond [(null? lst) (cons d ds)]
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[(equal? ds (syntax-list-shape (car lst)))
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(loop (cdr lst))]
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[else #f]))
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#f)]))
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(define-for-syntax (syntax-list-flatten e-stx)
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(reverse
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(let loop ([e-stx e-stx] [acc null])
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(define lst (syntax->list e-stx))
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(cond [(and lst (square-bracket? e-stx))
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(for/fold ([acc acc]) ([lst (in-list lst)])
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(loop lst acc))]
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[else
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(cons e-stx acc)]))))
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(define-syntax (array/syntax stx)
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(syntax-case stx ()
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[(_ orig-name constr ->array e)
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(let ([ds (syntax-list-shape #'e)])
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(unless ds
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(raise-syntax-error (syntax->datum #'orig-name) "expected rectangular data" stx #'e))
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(with-syntax ([(d ...) ds]
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[(v ...) (syntax-list-flatten #'e)])
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(syntax/loc stx
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(->array (vector d ...) (constr v ...)))))]))
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