;; guile-csv transform
;; Copyright (C) 2021
;; Brady McDonough

;; This program is free software; you can redistribute it and/or modify
;; it under the terms of the GNU Lesser General Public License as
;; published by the Free Software Foundation; either version 3 of the
;; License, or (at your option) any later version.
;;
;; 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
;; Lesser General Public License for more details.
;;
;; You should have received a copy of the GNU Lesser General Public
;; License along with this program; if not, contact:
;;
;; Free Software Foundation, Inc.     Voice:  +1-617-542-5942
;; 51 Franklin Street, Fifth Floor    Fax:    +1-617-542-2652
;; Boston, MA  02110-1301,  USA       gnu@gnu.org

(define-module (csv transform)
  #:use-module (ice-9 receive)
  #:use-module (sxml transform)
  #:export (bubble-term)
  #:reexport (pre-post-order))

(define (key-contains-defer str)
  (lambda ($pair) (string-contains (symbol->string (car $pair)) str)))

;; Generates a handler for pre-post-order.
;; EXAMPLE USAGE:
;; (pre-post-order $tree `(,(bubble-term rec "key-name")
;;                         (*default* . ,(lambda x x))))
;; This will generate a rule which travels in *preorder* to each record named
;;'rec' and replace the rec symbol with the pair keyed as "key-name"
(define-syntax bubble-term
  (syntax-rules ()
    ((_ record-sym $str)
     `(record-sym *preorder* .
                  ,(lambda $record
                     (let* (($lst (cadr $record)))
                       (receive (head rest)
                           (partition (key-contains-defer $str) $lst)
                         (cons head (cons rest '())))))))))