--- /dev/null
+;
+;
+; $Id$
+;
+; SuperTux 0.3.1 tileset splitter
+; Copyright (C) 2008 Christoph Sommer <christoph.sommer@2008.expires.deltadevelopment.de>
+;
+; 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 2
+; 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, write to the Free Software
+; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+;
+
+; ---------------------------------------------------------------------------
+; Reads a SuperTux tileset on stdin, outputs a SuperTux tileset with only
+; those tiles with a tile-id in the tileset's first group.
+; This means that if the tileset starts with a tilegroup "snow", you
+; will get a tileset with only snow tiles in the output
+; ---------------------------------------------------------------------------
+
+; return first sublist in haystack that starts with needle or #f if none is found
+(define (find-sublist haystack needle)
+ (cond
+ (
+ (not (pair? haystack))
+ #f
+ )
+ (
+ (and (pair? (car haystack)) (eq? (caar haystack) needle))
+ (cdar haystack)
+ )
+ (
+ else
+ (find-sublist (cdr haystack) needle)
+ )
+ )
+ )
+
+; input: (tile ... (id 1) ...) (1 2 3 4 5)
+; output: #t if "id" in "valid-ids", #f otherwise
+(define (output-tile? children valid-ids)
+ (let
+ ((id (car (find-sublist children 'id))))
+ (if (not id)
+ #f
+ )
+ (if (member id valid-ids)
+ #t
+ #f
+ )
+ )
+ )
+
+; input: (1 7 8) (1 2 3 4 5)
+; output: #t if any of "needles" in "haystack", #f otherwise
+(define (any-member needles haystack)
+ (if (null? needles)
+ #f
+ (or
+ (member (car needles) haystack)
+ (any-member (cdr needles) haystack)
+ )
+ )
+ )
+
+; input: (tiles ... (ids 1 7 8) ...) (1 2 3 4 5)
+; output: #t if any of "ids" in "valid-ids", #f otherwise
+(define (output-tiles? children valid-ids)
+ (let
+ ((ids (find-sublist children 'ids)))
+ (if (not ids)
+ #f
+ )
+ (if (any-member ids valid-ids)
+ #t
+ #f
+ )
+ )
+ )
+
+; input: ((tilegroup ...) (tilegroup ...) (tile ...) (tiles ...))
+; output: ((tilegroup ...) (tile ...) (tiles ...))
+(define (output-and-next children valid-ids)
+ (if (null? valid-ids)
+ ; tilegroup not yet found
+ (if (not (string=? (symbol->string (caar children)) "tilegroup"))
+ ; no tilegroup: just continue
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ (begin
+ ; tilegroup: get valid-ids
+ (set! valid-ids (find-sublist (car children) 'tiles))
+ ; output tilegroup and continue
+ (cons
+ (car children)
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ )
+ )
+ )
+ (begin
+ ; tilegroup already found
+ (cond
+ ((string=? (symbol->string (caar children)) "tile")
+ (if (output-tile? (car children) valid-ids)
+ (cons
+ (car children)
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ )
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ )
+ )
+ ((string=? (symbol->string (caar children)) "tiles")
+ (if (output-tiles? (car children) valid-ids)
+ (cons
+ (car children)
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ )
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ )
+ )
+ (else
+ (if (not (null? (cdr children))) (output-and-next (cdr children) valid-ids) '())
+ )
+ )
+ )
+ )
+ )
+
+; input: (supertux-tiles ... (tilegroup ...) (tilegroup ...) (tile ...) (tiles ...))
+; output: (supertux-tiles (tilegroup ...) (tile ...) (tiles ...))
+(define (clip-tileset supertux-tiles)
+ (let ()
+ (if (not (string=? (symbol->string (car supertux-tiles)) "supertux-tiles")) (error "not a supertux-tileset:" type))
+ (output-and-next (cdr supertux-tiles) '())
+ )
+ )
+
+; run conversion on stdin, output to stdout
+(write (clip-tileset (read)))
+(newline)
+(quit)
+