scsh-0.6/scsh/syntax.scm

86 lines
2.7 KiB
Scheme

;;; Syntax definitions for scsh.
;;; Translating process forms into Scheme code.
;;; Copyright (c) 1993 by Olin Shivers.
;;; The three basic forms for running an extended process form:
;;; EXEC-EPF, &, and RUN. EXEC-EPF is the foundation.
;; This is used by the macro for the << redirection to prevent the temporary
;; port from being closed by a GC before the process exec's
(define <<-port-holder)
(define-syntax exec-epf
(lambda (form rename compare)
(transcribe-extended-process-form (cdr form) rename compare)))
(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))