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95 lines
3.7 KiB
Racket
95 lines
3.7 KiB
Racket
#lang racket
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(require (for-syntax (planet mb/pollen/tools)
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(planet mb/pollen/world)))
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(require (planet mb/pollen/tools)
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(planet mb/pollen/world))
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Look for a EXTRAS_DIR directory local to the source file.
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;; If it exists, get list of rkt files
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;; and require + provide them.
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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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(require racket/contract/region)
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(define-for-syntax (is-rkt-file? x) (has-ext? x 'rkt))
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(define-for-syntax (make-complete-path x)
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(define-values (start_dir name _ignore)
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(split-path (path->complete-path x)))
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(build-path start_dir EXTRAS_DIR name))
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(define-syntax (require-and-provide-extras stx)
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(if (directory-exists? EXTRAS_DIR)
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(letrec
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([files (map make-complete-path (filter is-rkt-file? (directory-list EXTRAS_DIR)))]
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[files-in-require-form
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(map (λ(x) `(file ,(path->string x))) files)])
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(datum->syntax stx
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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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; if no files to import, do nothing
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#'(begin))) ; tried (void) here but it doesn't work: prints <void>
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; todo: merge with function above
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(define-syntax (require-extras stx)
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(if (directory-exists? EXTRAS_DIR)
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(letrec
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([files (map make-complete-path (filter is-rkt-file? (directory-list EXTRAS_DIR)))]
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[files-in-require-form
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(map (λ(x) `(file ,(path->string x))) files)])
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(datum->syntax stx
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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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#'(begin)))
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; AHA! This is how to make an identifier secretly behave as a runtime function
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; first, define the function as syntax-rule
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(define-syntax-rule (get-here)
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(begin ; define-syntax-rule must have a single expression in the body
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; also, even though begin permits defines,
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; macro might be used in an expression context, whereupon they will cause an error.
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; so best to use let
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(let ([ccr (current-contract-region)]) ; trick for getting current module name
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(when (list? ccr) ; if contract-region is called from within submodule, you get a list
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(set! ccr (car ccr))) ; in which case, just grab the path from the front
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(if (equal? 'pollen-lang-module ccr) ; what happens if the file isn't yet saved in drracket
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'nowhere ; thus you are nowhere
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(match-let-values ([(_ here-name _) (split-path ccr)])
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(path->string (remove-all-ext here-name)))))))
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; then, apply a separate syntax transform to the identifier itself
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; can't do this in one step, because if the macro goes from identifier to function definition,
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; macro processor will evaluate the body at compile-time, not runtime.
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(define-syntax here
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(λ(stx) (datum->syntax stx '(get-here))))
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; function to strip metas out of body and consolidate them separately
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(define (split-metas body)
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(define meta-list '())
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(define (&split-metas x)
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(cond
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[(and (named-xexpr? x) (equal? 'meta (car x)))
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(begin
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(set! meta-list (cons x meta-list))
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empty)]
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[(named-xexpr? x) ; handle named-xexpr
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(let-values([(name attr body) (xexplode x)])
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(make-xexpr name attr (&split-metas body)))]
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[(list? x) (map &split-metas x)]
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[else x]))
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(values (remove-empty (&split-metas body)) (reverse meta-list)))
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(provide (all-defined-out))
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(module+ test
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(require rackunit)
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(check-equal? (get-here) "test-main-helper")) |