pollen/main-helper.rkt

#lang racket/base
(require (for-syntax racket/base pollen/project-requires))

(require racket/contract/region)

(provide (all-defined-out) (all-from-out racket/contract/region))

(define-for-syntax (put-file-in-require-form file)
  `(file ,(path->string file)))

(define-for-syntax (do-project-require-file-syntax stx #:provide? [provide? #f])
  (define project-require-files (get-project-require-files))
  (if project-require-files
      (let ([files-in-require-form (map put-file-in-require-form project-require-files)])
        (datum->syntax stx `(begin
                              (require ,@files-in-require-form)
                              ,@(if provide? 
                                    (list `(provide (all-from-out ,@files-in-require-form))) 
                                    '()))))
      ; if no files to import, do nothing
      #'(begin)))

(define-syntax (require-and-provide-project-require-files stx)
  (do-project-require-file-syntax stx #:provide? #t))

(define-syntax (require-project-require-files stx)
  (do-project-require-file-syntax stx))


;; here = path of this file, relative to current directory. 
;; We want to make this identifier behave as a runtime function
;; This requires two steps.
;; First, define the underlying function as syntax-rule
(define-syntax (get-here-path stx)
  (datum->syntax stx 
                 '(begin 
                    ;; Even though begin permits defines,
                    ;; This macro might be used in an expression context, 
                    ;; whereupon define would cause an error. Therefore, use let.
                    (let* ([ccr (current-contract-region)] ; trick for getting current module name
                           [hp (cond
                                 ;; if contract-region is called from within submodule,
                                 ;; you get a list
                                 ;; in which case, just grab the path from the front
                                 [(list? ccr) (car ccr)]
                                 ;; file isn't yet saved in drracket
                                 [(equal? 'pollen-lang-module ccr) 'nowhere] 
                                 [else ccr])])
                      ;; pass complete path back as here value (as string)
                      ;; Why not relative to current-directory? 
                      ;; Because current-directory can't be parameterized
                      ;; so raises possibility of inconsistent values.
                      ;; Whereas the complete path is unambiguous,
                      ;; and can be made relative by the caller (or otherwise altered).
                      ((bound/c ->string) hp)))))


; Second step: apply a separate syntax transform to the identifier itself
; We can't do this in one step, because if the macro goes from identifier to function definition,
; The macro processor will evaluate the body at compile-time, not at runtime.
(define-syntax here-path (λ(stx) (datum->syntax stx '(get-here-path))))