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82 lines
3.7 KiB
Racket
82 lines
3.7 KiB
Racket
#lang racket
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(require racket/contract/region)
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;; use full planet paths because this file is evaluated from source directory,
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;; not module directory
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(require (for-syntax (planet mb/pollen/tools) (planet mb/pollen/world)))
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(require (planet mb/pollen/tools) (planet mb/pollen/world))
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(provide (all-defined-out))
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(module+ test (require rackunit))
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;; Look for an EXTRAS_DIR directory local to the source file.
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;; and require all the .rkt files therein.
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;; optionally provide them.
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(define-syntax (require-extras stx #:provide [provide #f])
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(cond
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[(directory-exists? EXTRAS_DIR)
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;; This will be resolved in the context of current-directory.
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;; So when called from outside the project directory,
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;; current-directory must be properly set with 'parameterize'
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(define (make-complete-path path)
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;; todo: document why this function is necessary (it definitely is, but I forgot why)
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(define-values (start_dir name _ignore) (split-path (path->complete-path path)))
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(build-path start_dir EXTRAS_DIR name))
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(define files (map make-complete-path (filter (λ(i) (has-ext? i 'rkt)) (directory-list EXTRAS_DIR))))
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(define files-in-require-form
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(map (λ(file) `(file ,(->string file))) files))
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(datum->syntax stx
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(if provide
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`(begin
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(require ,@files-in-require-form)
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(provide (all-from-out ,@files-in-require-form)))
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`(begin
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(require ,@files-in-require-form))))]
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; if no files to import, do nothing
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[else #'(begin)]))
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;; here = path of this file, relative to current directory.
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;; We want to make this identifier behave as a runtime function
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;; This requires two steps.
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;; First, define the underlying function as syntax-rule
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(define-syntax (get-here stx)
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(datum->syntax stx
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'(begin
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;; Even though begin permits defines,
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;; This macro might be used in an expression context,
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;; whereupon define would cause an error.
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;; Therefore, best to use let.
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(let* ([ccr (current-contract-region)] ; trick for getting current module name
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[here-path (cond
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;; if contract-region is called from within submodule,
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;; you get a list
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;; in which case, just grab the path from the front
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[(list? ccr) (car ccr)]
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;; file isn't yet saved in drracket
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[(equal? 'pollen-lang-module ccr) 'nowhere]
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[else ccr])])
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;; pass complete path back as here value (as string)
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;; Why not relative to current-directory?
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;; Because current-directory can't be parameterized
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;; so raises possibility of inconsistent values.
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;; Whereas the complete path is unambiguous,
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;; and can be made relative by the caller (or otherwise altered).
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(->string here-path)))))
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;; todo: update tests
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;(module+ test
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; (check-equal? (get-here) "main-helper.rkt"))
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; Second step: apply a separate syntax transform to the identifier itself
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; We can't do this in one step, because if the macro goes from identifier to function definition,
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; The macro processor will evaluate the body at compile-time, not at runtime.
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(define-syntax here (λ(stx) (datum->syntax stx '(get-here))))
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;; todo: update test
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;(module+ test
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; (check-equal? here "main-helper.rkt"))
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