/usr/share/guile/site/container/nodal-tree.scm is in guile-library 0.2.1-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 | ;; (container nodal-tree) -- a tree data structure
;; Copyright (C) 2003,2004 Andy Wingo <wingo at pobox dot com>
;; 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, 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 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 <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;;A nodal tree is a tree composed of nodes, each of which may have
;;children. Nodes are represented as alists. The only alist entry that
;;is specified is @code{children}, which must hold a list of child
;;nodes. Other entries are intentionally left unspecified, so as to
;;allow for extensibility.
;;
;;; Code:
(define-module (container nodal-tree)
#:export (nodal-tree? make-node
node-ref node-set! node-children))
;; Returns pairs, not lists
(define (group-pairs l)
(let lp ((in l) (out '()))
(cond
((null? in) (reverse! out))
(else (lp (list-cdr-ref in 2) (acons (car in) (cadr in) out))))))
(define (make-node . attributes)
(or (even? (length attributes)) (error "invalid node atrributes"))
(cons 'nodal-tree
(let ((body (group-pairs attributes)))
(if (assq 'children body)
body
(acons 'children '() body)))))
(define (node-set! node name val)
(set-cdr! node (assq-set! (cdr node) name val)))
(define (node-ref node name)
(assq-ref (cdr node) name))
(define (node-children node)
(or (node-ref node 'children) '()))
(define (nodal-tree? x)
"Predicate to determine if @var{x} is a nodal tree. Not particularly
efficient: intended for debugging purposes."
(and (list? x)
(eq? (car x) 'nodal-tree)
(and-map pair? x)
(and-map nodal-tree? (node-children x))))
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