;;; Gash -- Guile As SHell
;;; Copyright © 2018 Timothy Sample <samplet@ngyro.com>
;;;
;;; This file is part of Gash.
;;;
;;; Gash is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; Gash is distributed in the hope that it will be useful, but WITHOUT ANY
;;; WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
;;; FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
;;; details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with Gash.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gash built-ins utils)
  #:use-module (ice-9 match)
  #:export (get-evaluator
            split-assignment))

;;; Commentary:
;;;
;;; Utility functions shared by built-ins.
;;;
;;; Code:

;; We need to be able to run Shell code from the 'dot' and 'eval'
;; built-ins.  This is a bit of trickery to avoid a module dependency
;; loop.
(define (get-evaluator)
  (module-ref (resolve-interface '(gash eval)) 'eval-sh))

(define (split-assignment assignment)
  (match (string-index assignment #\=)
    (#f (values assignment #f))
    (index (let ((name (substring assignment 0 index)))
             (match (substring assignment (1+ index))
               ((? string-null?) (values name #f))
               (value (values name value)))))))
