;; ncompile v180819b
;; usage:
;;   (ncompile-file "foo.m")
;; first checks for first line of the form
;;   #lang <from-language>
;; then uses file ending ".m" => nx-matlab


(define-module (ncompile)
  #:export (ncompile-file)
  )

(define (lang-from-port port)

  (define (release chl)
    (let loop ((chl chl))
      (unless (null? chl)
	(unread-char (car chl) port)
	(loop (cdr chl))))
    #f)

  (define (return chl)
    (string->symbol (reverse-list->string chl)))
	  
  (let loop ((cl '()) (st 0) (kl '(#\# #\l #\a #\n #\g)) (ch (read-char port)))
    (case st
      ((0) (cond			; read `#lang'
	    ((eof-object? ch) (release cl))
	    ((null? kl) (loop cl 1 kl ch))
	    ((char=? ch (car kl))
	     (loop (cons ch cl) st (cdr kl) (read-char port)))
	    (else (release (cons ch cl)))))
      ((1) (cond			; skip spaces
	    ((eof-object? ch) (release cl))
	    ((char=? ch #\space) (loop (cons ch cl) st kl (read-char port)))
	    (else (loop cl 2 '() ch))))
      ((2) (cond			; collect lang name
	    ((eof-object? ch) (return kl))
	    ((char=? ch #\newline) (return kl))
	    ((char-whitespace? ch) (loop cl 3 kl ch))
	    (else (loop cl st (cons ch kl) (read-char port)))))
      ((3) (cond
	    ((eof-object? ch) (return kl))
	    ((char=? ch #\newline) (return kl))
	    (else (loop cl st kl (read-char port))))))))

(define %file-extension-map
  '(("scm" . scheme)
    ("el" . elisp)
    ("m" . nx-matlab)
    ("js" . ecmascript)))

(define* (lang-from-file file)
  (let* ((ix (string-rindex file #\.))
	(ext (and ix (substring file (1+ ix)))))
    (and ext (assoc-ref %file-extension-map ext))))

(define call-with-output-file/atomic
  (@@ (system base compile) call-with-output-file/atomic))
(define language-printer
  (@ (system base language) language-printer))
(define ensure-language
  (@@ (system base compile) ensure-language))
(define ensure-directory
  (@@ (system base compile) ensure-directory))
(define read-and-compile
  (@@ (system base compile) read-and-compile))
(define compiled-file-name
  (@@ (system base compile) compiled-file-name))
(define default-environment
  (@@ (system base compile) default-environment))

(define* (ncompile-file file #:key
			(output-file #f)
			(from #f)
			(to 'bytecode)
			(env #f)
			(opts '())
			(canonicalization 'relative))
  (with-fluids ((%file-port-name-canonicalization canonicalization))
    (let* ((comp (or output-file (compiled-file-name file)
                     (error "failed to create path for auto-compiled file"
                            file)))
           (in (open-input-file file))
           (enc (file-encoding in)))
      ;; Choose the input encoding deterministically.
      (set-port-encoding! in (or enc "UTF-8"))

      (ensure-directory (dirname comp))
      (call-with-output-file/atomic comp
	(lambda (port)
	  (let* ((from (or from
			   (lang-from-port in)
			   (lang-from-file file)
			   (current-language)))
		 (env (or env (default-environment from))))
	    (simple-format (current-error-port) "compiling from lang ~A\n" from)
	    ((language-printer (ensure-language to))
	     (read-and-compile in #:env env #:from from #:to to #:opts
			       (cons* #:to-file? #t opts))
	     port)))
	  file)
	comp)))

;; Local Variables:
;; eval: (put 'call-with-output-file/atomic 'scheme-indent-function 1)
;; End:
;; --- last line ---