;;; Copyright (C) Peter McGoron 2024
;;; This program 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, version 3 of the License.
;;; 
;;; This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
;;; 
;;; Simple COND-EXPAND using SYNTAX-RULES. Designed for chez.

(define-syntax cond-expand-conditional
  (syntax-rules (and or not chez r6rs)
    ;; Defined keywords
    ((cond-expand-conditional chez execute alt) execute)
    ((cond-expand-conditional r6rs execute alt) execute)
    ;; Conditional statements: AND
    ((cond-expand-conditional (and e1 e2 ...) execute alt)
     (cond-expand-conditional e1
                              (cond-expand-conditional
                               (and e2 ...)
                               execute
                               alt)
                              alt))
    ((cond-expand-conditional (and) execute alt) execute)
    ;; OR
    ((cond-expand-conditional (or e1 e2 ...) execute alt)
     (cond-expand-conditional e1 execute
                              (cond-expand-conditional
                               (or e2 ...) execute alt)))
    ((cond-expand-conditional (or) execute alt) alt)
    ;; NOT
    ((cond-expand-conditional (not e) execute alt)
     (cond-expand-conditional e alt execute))
    ;; All other conditions
    ((cond-expand-conditional unknown execute alt) alt)))

(define-syntax cond-expand
  (syntax-rules (else)
    ((cond-expand (else evaluated ...)) (begin evaluated ...))
    ((cond-expand (conditional evaluated ...) rest ...)
     (cond-expand-conditional conditional
                              (begin evaluated ...)
                              (cond-expand rest ...)))))