;;; Syntax definitions for scsh.
;;; Translating process forms into Scheme code.

;; Copyright (c) 1993 by Olin Shivers
;; Copyright (c) 2010 Clinton Ebadi

(define-modules (scsh syntax)
  #:use-module (scsh syntax-helpers)
  #:export (exec-pf
	    || && :or:
	    run/collecting
	    run/port+proc
	    run/port
	    run/strings
	    run/file
	    run/string
	    run/sexp
	    run/sexps
	    run/pty))

;;; The three basic forms for running an extended process form:
;;; EXEC-EPF, &, and RUN. EXEC-EPF is the foundation.

(define-syntax exec-epf
  (lambda (form)
    (syntax-case form ()
      ((_ forms ...)
       (expand-process-form #'(forms ...))))))


(define-simple-syntax (& . epf)
  (fork (lambda () (exec-epf . epf))))

(define-simple-syntax (run . epf)
  (wait (& . epf)))

;;; Sequencing operators:
;;;
;;; (|| pf1 ... pfn)
;;;     Run each proc until one completes successfully (i.e., exit status 0).
;;;     Return true if some proc completes successfully; otherwise #f.
;;;
;;; (&& pf1 ... pfn) 
;;;     Run each proc until one fails (i.e., exit status non-0).
;;;     Return true if all procs complete successfully; otherwise #f.

;;; WARNING: || is not a readable symbol in R4RS.

(define-simple-syntax (|| pf ...) (or  (zero? (run pf)) ...))
(define-simple-syntax (:or: pf ...) (or  (zero? (run pf)) ...))
(define-simple-syntax (&& pf ...) (and (zero? (run pf)) ...))

(define-simple-syntax (run/collecting fds . epf)
  (run/collecting* `fds (lambda () (exec-epf . epf))))

(define-simple-syntax (run/port+proc . epf)
  (run/port+proc* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/port . epf)
  (run/port* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/strings . epf)
  (run/strings* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/file . epf)
  (run/file* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/string . epf)
  (run/string* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/sexp . epf)
  (run/sexp* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/sexps . epf)
  (run/sexps* (lambda () (exec-epf . epf))))

(define-simple-syntax (run/pty . epf)
  (run/pty* (lambda () (exec-epf . epf))))

;(define (expand-mac transformer form)
;  (transformer form (lambda (x) x) eq?))

;(define-simple-syntax (test-mac trans . form)
;  (pp (expand-mac trans (quote form))))


;; Return a Unix port such that reads on it get the chars produced by
;; DISPLAYing OBJ. For example, if OBJ is a string, then reading from
;; the port produces the characters of OBJ.
;; 
;; This implementation works by writing the string out to a temp file,
;; but that isn't necessary. It could work, for example, by forking off a 
;; writer process that outputs to a pipe, i.e.,
;;     (run/port (begin (display obj (fdes->outport 1))))

(define (open-string-source obj)
  (receive (inp outp) (temp-file-channel)
    (display obj outp)
    (close-output-port outp)
    inp))