This file is indexed.

/usr/share/uim/sxml-tools.scm is in uim-data 1:1.8.6+gh20180114.64e3173-2build2.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

  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
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
;;                            S X M L   T o o l s               
; $Revision: 3.14 $ from $Date: 2003/12/23 05:39:31 $:
;
; This software is in Public Domain.
; IT IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND.
;
; Please send bug reports and comments to lisovsky@acm.org
;           Kirill Lisovsky
;
;   SXML normal form used for normalization-dependent functions:
; If attr-list is present it's always the second in SXML element.
; If aux-list is present - then list of attributes is always
; included, and aux-list is always the third.
;   Minimized form is just the same, but all the empty aux-lists are 
; absent, and empty attr-lists are present only in elements with aux-lists
; present. 

;==============================================================================
; Auxiliary functions.

(define (make-char-quotator char-encoding)
  (let ((bad-chars (map car char-encoding)))

    ; Check to see if str contains one of the characters in charset,
    ; from the position i onward. If so, return that character's index.
    ; otherwise, return #f
    (define (index-cset str i charset)
      (let loop ((i i))
        (and (< i (string-length str))
             (if (memv (string-ref str i) charset) i
                 (loop (inc i))))))

    ; The body of the function
    (lambda (str)
      (let ((bad-pos (index-cset str 0 bad-chars)))
        (if (not bad-pos) str   ; str had all good chars
            (let loop ((from 0) (to bad-pos))
              (cond
               ((>= from (string-length str)) '())
               ((not to)
                (cons (substring str from (string-length str)) '()))
               (else
                (let ((quoted-char
                       (cdr (assv (string-ref str to) char-encoding)))
                      (new-to
                       (index-cset str (inc to) bad-chars)))
                  (if (< from to)
                      (cons
                       (substring str from to)
                       (cons quoted-char (loop (inc to) new-to)))
                      (cons quoted-char (loop (inc to) new-to))))))))))
))

; unlike filter-map from SRFI-1 this function uses separate predicate 
; and mapping functions. 
; Applies proc to  all the elements of source list that satisfy the predicate 
; and return the list of the results.
(define (filter-and-map pred proc lis)			
  (let rpt ((l lis))		
    (if (null? l)
      '()
      (if (pred (car l))
	(cons (proc (car l)) (rpt (cdr l)))
	(rpt (cdr l))))))
      
; Applies pred to every member of lst and yields #t if all the results
; are #t
(define (check-list pred lst) 
  (cond
    ((null? lst) #t)
    ((pred (car lst))
     (check-list pred (cdr lst)))
    (else #f)))

; Returns attr-list node for a given obj 
;   or #f if it is absent
(define (sxml:attr-list-node obj)
  (if (and (not (null? (cdr obj)))
	    (pair? (cadr obj)) 
	    (eq? '% (caadr obj)))
	 (cadr obj)
	 #f))

; Returns attr-list wrapped in list
;   or '((%)) if it is absent and aux-list is present 
;   or '() if both lists are absent
(define (sxml:attr-as-list obj)
  (cond
    ((sxml:attr-list-node obj)
     => list)
    ((sxml:aux-list-node obj)
     '((%)))
    (else '())))


; Returns aux-list node for a given obj 
;   or #f if it is absent
(define (sxml:aux-list-node obj)
  (if
    (or (null? (cdr obj))
	(null? (cddr obj))
	(not (pair? (caddr obj)))
	(not (eq? (caaddr obj) '%%)))
    #f
    (caddr obj)))

; Returns aux-list wrapped in list 
;   or '() if it is absent
(define (sxml:aux-as-list obj)
  (cond 
    ((sxml:aux-list-node obj)
     => list)
    (else '())))

; optimized (string-rindex name #\:)
; returns position of a separator between namespace-id and LocalName
(define-macro (sxml:find-name-separator len)
  `(let rpt ((pos (mm ,len))) 
     (cond
       ((negative? pos) #f) 	
       ((char=? #\: (string-ref name pos)) pos)
       (else (rpt (mm pos))))))
  

;==============================================================================
; Predicates

; Predicate which returns #t if given element <obj> is empty. 
; Empty element has no nested elements, text nodes, PIs, Comments or entities
; but it may contain attributes or namespace-id.
; It is a SXML counterpart of XML empty-element.
(define (sxml:empty-element? obj)
  (not 
    ((select-first-kid 
     (lambda(x)
       (or ((ntype-names?? '(*PI* *COMMENT* *ENTITY*)) x)
           ((ntype?? '*) x)
	   (string? x)))) obj)))

; Returns #t if the given <obj> is shallow-normalized SXML element.
; The element itself has to be normalised but its nested elements are not tested.
(define (sxml:shallow-normalized? obj)
  (or 
    (null? (cdr obj))
    (and (or 
	   (and 
	     (pair? (cadr obj)) 
	     (eq? (caadr obj) '%))
	   (not ((select-first-kid (ntype-names?? '(% %%))) obj)))
	 (or (null? (cddr obj))
	     (and (pair? (caddr obj)) 
		  (eq? (caaddr obj) '%%))
	     (not ((select-first-kid (ntype?? '%%)) obj))))))

; Returns #t if the given <obj> is normalized SXML element.
;  The element itself and all its nested elements have to be normalised.
(define (sxml:normalized? obj)
    (and
      (sxml:shallow-normalized? obj)
    (check-list
      (lambda(x)
	(if
	   (sxml:element? x)
	   (sxml:normalized? x)
	   #t))
       (sxml:content obj))
    ))

; Returns #t if the given <obj> is shallow-minimized SXML element.
; The element itself has to be minimised but its nested elements are not tested.
(define (sxml:shallow-minimized? obj)
  (and
    (sxml:shallow-normalized? obj)
    (not (and (sxml:aux-list-node obj) 
	      (null? (sxml:aux-list obj))))
    (not (and (sxml:attr-list-node obj)
	      (null? (sxml:attr-list obj))
	      (not (sxml:aux-list-node obj))))))

; Returns #t if the given <obj> is minimized SXML element.
;  The element itself and all its nested elements have to be minimised.
(define (sxml:minimized? obj)
    (and
      (sxml:shallow-minimized? obj)
    (check-list
      (lambda(x)
	(if
	   (sxml:element? x)
	   (sxml:minimized? x)
	   #t))
       (sxml:content obj))
    ))

;==============================================================================
; Accessors  

; Returns a name of a given SXML node
; It is introduced for the sake of encapsulation.
(define sxml:name car)

; A version of sxml:name, which returns #f if the given <obj> is 
; not a SXML element.
; Otherwise returns its name.
(define (sxml:element-name obj)
  (and ((ntype?? '*) obj) 
       (car obj)))

; Safe version of sxml:name, which returns #f if the given <obj> is 
; not a SXML node.
; Otherwise returns its name.
(define (sxml:node-name obj)
  (and (pair? obj) 
       (symbol? (car obj))
    (car obj)))

; Returns Local Part of Qualified Name (Namespaces in XML production [6])
; for given obj, which is ":"-separated suffix of its Qualified Name
; If a name of a node given is NCName (Namespaces in XML production [4]), then 
; it is returned as is.
; Please note that while SXML name is a symbol this function returns a string.
(define (sxml:ncname obj)
  (let* ((name (symbol->string (car obj)))
	 (len (string-length name)))
    (cond
      ((sxml:find-name-separator len)
       => (lambda (pos) 
	    (substring name (+ pos 1) len)))
      (else name))))

; Returns namespace-id part of given name, or #f if it's LocalName
(define (sxml:name->ns-id sxml-name)
  (let* ((name (symbol->string sxml-name)))
    (cond
      ((sxml:find-name-separator (string-length name))
       => (lambda (pos) 
	    (substring name  0 pos)))
      (else #f))))
    

; Returns the content of given SXML element or nodeset (just text and element
; nodes) representing it as a list of strings and nested elements in document 
; order.  This list is empty if <obj> is empty element or empty list.
(define (sxml:content obj)
  (((if (nodeset? obj) 
      sxml:filter
      select-kids) 
    (lambda(x)
      (or
	(string? x)   ;  ((ntype?? '*text*) x)
       ((ntype?? '*) x)))) 
   obj))

; Returns a string which combines all the character data 
; from text node childrens of the given SXML element
; or "" if there is no text node children
(define (sxml:text obj)
  (let ((tnodes
	 ((select-kids
	   string?) 
	   obj)))
    (cond 
      ((null? tnodes) "")
      ((null? (cdr tnodes))
       (car tnodes))
      (else (string-intersperse tnodes "")))))

;------------------------------------------------------------------------------
; Normalization-dependent accessors
;
;
; "Universal" accessors are less effective but may be used for non-normalized SXML
; Safe accessors are named with suffix '-u'
;
; "Fast" accessors are optimized for normalized SXML data.
; They are not applicable to arbitrary non-normalized SXML data
; Their names has no specific suffixes

; Returns all the content of normalized SXML element except attr-list and
; aux-list.
; Thus it includes PI, COMMENT and  ENTITY nodes as well as TEXT and ELEMENT nodes
; returned by sxml:content.
; Returns  a list of nodes in document order or empty list if <obj> is empty 
; element or empty list.
; This function is faster than sxml:content
(define (sxml:content-raw obj)
  ((if (and (not (null? (cdr obj))) 
	    (pair? (cadr obj)) (eq? (caadr obj) '%))
     (if (and (not (null? (cddr obj))) 
	      (pair? (caddr obj)) (eq? (caaddr obj) '%%))
       cdddr
       cddr)
     cdr) obj))


; Returns the list of attributes for given element or nodeset.
; Analog of ((sxpath '(% *)) obj)
; Empty list is returned if there is no list of attributes.
(define (sxml:attr-list-u obj)
  (cond (((select-first-kid (ntype?? '%)) obj)
	 => cdr)
	(else '())))

; Returns the list of auxiliary nodes for given element or nodeset.
; Analog of ((sxpath '(%% *)) obj)
; Empty list is returned if a list of auxiliary nodes is absent.
(define (sxml:aux-list obj)
  (if
    (or (null? (cdr obj))
	(null? (cddr obj))
	(not (pair? (caddr obj)))
	(not (eq? (caaddr obj) '%%)))
    '()
    (cdaddr obj)))  

; Returns the list of auxiliary nodes for given element or nodeset.
; Analog of ((sxpath '(%% *)) obj)
; Empty list is returned if a list of auxiliary nodes is absent.
(define (sxml:aux-list-u obj)
  (cond (((select-first-kid (ntype?? '%%)) obj)
	 => cdr)
	(else '())))

; Return the first aux-node with <aux-name> given in SXML element <obj> 
; or #f is such a node is absent.
; NOTE: it returns just the FIRST node found even if multiple nodes are
; present, so it's mostly intended for nodes with unique names 
(define (sxml:aux-node obj aux-name)
  (cond 
    ((assq aux-name (sxml:aux-list obj)))
    (else #f))) 

; Return a list of aux-node with <aux-name> given in SXML element <obj> 
; or '() if such a node is absent.
(define (sxml:aux-nodes obj aux-name)
  (filter 
    (lambda(x) (eq? aux-name (car x)))
    (sxml:aux-list obj)))

; Accessor for an attribute <attr-name> of given SXML element <obj> which 
; It returns: 
;    the value of the attribute if the attribute is present
;    #f if there is no such an attribute in the given element
(define (sxml:attr obj attr-name)
  (cond 
    ((assq attr-name (sxml:attr-list obj))
     => cadr)
    (else #f)))

; Extracts a value of attribute with given name from attr-list
(define (sxml:attr-from-list attr-list name)
	    (cond 
	      ((assq name attr-list) 
	       => cadr)
	      (else #f)))

; Accessor for a numerical attribute <attr-name> of given SXML element <obj> 
; which It returns: 
;    a value of the attribute as the attribute as a number if the attribute 
;    is present and its value may be converted to number using string->number
;    #f if there is no such an attribute in the given element or
;    its value can't be converted to a number
(define (sxml:num-attr obj attr-name)
  (cond 
    ((assq attr-name (sxml:attr-list obj))
     => (lambda(x) (string->number (cadr x))))
    (else #f)))

; Accessor for an attribute <attr-name> of given SXML element <obj> which 
; may also be an attributes-list or nodeset (usually content of SXML element)
;
; It returns: 
;    the value of the attribute if the attribute is present
;    #f if there is no such an attribute in the given element
(define (sxml:attr-u obj attr-name)
  (cond 
    ((assq attr-name
	   ; the list of attributes is computed below
	   (cond
	     ((and (not (null? (cdr obj))) 
		   (pair? (cadr obj))
		   (eq? '% (caadr obj)))
	      (cdadr obj))   ; fast track for normalized elements 
	     ((eq? '% (car obj))
	      (cdr obj))     ; if applied to attr-list
	     (else (sxml:attr-list-u obj))))
     => cadr)
    (else #f)))

; Returns the list of namespaces for given element.
; Analog of ((sxpath '(%% *NAMESPACES* *)) obj)
; Empty list is returned if there is no list of namespaces.
(define (sxml:ns-list obj)
  (cond ((assv '*NAMESPACES* (sxml:aux-list obj))
	 => cdr)
	(else '())))

; Returns the list of namespace-assoc's for given namespace-id in 
; SXML element <obj>.
; Analog of ((sxpath '(%% *NAMESPACES* namespace-id)) obj)
; Empty list is returned if there is no namespace-assoc with namespace-id
; given.
(define (sxml:ns-id->nodes obj namespace-id)
  (filter 
    (lambda(x)
      (eq? (car x) namespace-id))
    (sxml:ns-list obj)))

; It returns: 
;    A  URI's for namespace-id given 
;    #f if there is no namespace-assoc with namespace-id given
(define (sxml:ns-id->uri obj namespace-id)
  (cond 
    ((assq namespace-id (sxml:ns-list obj))
     => cadr)
    (else #f)))

; Returns a list of namespace-assocs nodes for NS URI given 
(define (sxml:ns-uri->nodes obj URI)
  (filter
    (lambda (ns-assoc) 
      (string=? (cadr ns-assoc) URI))
    (sxml:ns-list obj)))

; Returns a namespace-id for NS URI given 
(define (sxml:ns-uri->id obj URI)
  (let rpt ((ns-assocs (sxml:ns-list obj)))
  (cond
      ((null? ns-assocs) #f)
      ((string=? (cadar ns-assocs) URI)
       (caar ns-assocs))
      (else (rpt (cdr ns-assocs)))
    )))

; Returns namespace-id for given namespace-assoc list
(define sxml:ns-id car)

; Returns URI for given namespace-assoc list
(define sxml:ns-uri cadr)

; It returns namespace prefix for given namespace-assoc list
;  Original (as in XML document) prefix for namespace-id given 
; has to be strored as the third element in namespace-assoc list 
; if it is different from namespace-id.
;    If original prefix is omitted in namespace-assoc then
;      namespace-id is used instead
(define (sxml:ns-prefix ns-assoc)
      (if (> (length ns-assoc) 2)
	(caddr ns-assoc)
	(car ns-assoc))) 

;==============================================================================
; Data modification functions
; Constructors and mutators for normalized SXML data
; 
; This functions are optimized for normalized SXML data.
; They are not applicable to arbitrary non-normalized SXML data
; 
; Most of the functions are provided in two variants: 
; 1. side-effect intended functions for linear update of given elements.
;   Their names are ended with exclamation mark.
;   An example: 
;      sxml:change-content! 
; 2. pure functions without side-effects which return modified elements.
;   An example: 
;      sxml:change-content
 
; Change the content of given SXML element to <new-content>
; If <new-content> is an empty list then the <obj> is transformed 
; The resulting SXML element is normalized
; Former name sxml:content!
(define (sxml:change-content! obj new-content)
  (set-cdr! obj 
	    `(
              ,@(sxml:attr-as-list obj)
              ,@(sxml:aux-as-list obj)
	      ,@new-content)))

; Change the content of given SXML element to <new-content>
; If <new-content> is an empty list then the <obj> is transformed 
; to an empty element
; The resulting SXML element is normalized
(define (sxml:change-content obj new-content)
  `(,(sxml:name obj) 
              ,@(sxml:attr-as-list obj)
              ,@(sxml:aux-as-list obj)
	,@new-content))

; The resulting SXML element is normalized, if <new-attrlist> is empty,
; the cadr of <obj> is (%)
(define (sxml:change-attrlist obj new-attrlist)
  `(,(sxml:name obj) 
     ,@(cond 
	 (new-attrlist
	  `((% ,@new-attrlist)))
	 ((sxml:aux-list-node obj)
	   '((%)))
	 (else `()))
     ,@(sxml:aux-as-list obj)
     ,@(sxml:content obj)))

; The resulting SXML element is normalized, if <new-attrlist> is empty,
; the cadr of <obj> is (%)
; Former name sxml:attrlist!
(define (sxml:change-attrlist! obj new-attrlist)
  (set-cdr! obj 
	`(
	  ,@(cond 
	      (new-attrlist
		`((% ,@new-attrlist)))
	      ((sxml:aux-list-node obj)
	       '((%)))
	      (else `()))
	  ,@(sxml:aux-as-list obj)
	  ,@(sxml:content obj))))
      
; Change a name of SXML element destructively
; Former name was 'sxml:name!'
(define (sxml:change-name! obj new-name)
  (set-car! obj new-name))

; Returns SXML element with its name changed 
(define (sxml:change-name obj new-name)
  (cons new-name (cdr obj)))

; Returns SXML element <obj> with attribute <attr> added or #f
; if the attribute with given name already exists, 
; <attr> is (<attr-name> <attr-value>)
; Pure functional counterpart to sxml:add-attr!
(define (sxml:add-attr obj attr)
  (let ((attr-list (sxml:attr-list obj)))
    (if (assq (car attr) attr-list) 
      #f
      `(,(sxml:name obj)
	(% ,@(cons attr attr-list))
	,@(sxml:aux-as-list obj)
	,@(sxml:content obj)))))

; Add an attribute <attr> for an element <obj>
; Returns #f if the attribute with given name already exists. 
; The resulting SXML node is normalized.
; Linear update counterpart to sxml:add-attr
(define (sxml:add-attr! obj attr)
  (let ((attr-list (sxml:attr-list obj)))
    (if (assq (car attr) attr-list) 
      #f
      (begin
      (set-cdr! obj 
	`(
	(% ,@(cons attr attr-list))
	,@(sxml:aux-as-list obj)
	,@(sxml:content obj)))
      obj))))


; Returns SXML element <obj> with changed value of attribute <attr> or #f
; if where is no attribute with given name. 
; <attr> is (<attr-name> <attr-value>)
(define (sxml:change-attr obj attr)
  (let ((attr-list (sxml:attr-list obj)))
    (if (null? attr-list)
      #f
      (cond 
	((assv (car attr) attr-list) 
	 => (lambda (y)
	      `(,(sxml:name obj)
		 (% ,@(map
			(lambda(at)
			  (if
			    (eq? at y)
			    attr
			    at))
			attr-list))
		 ,@(sxml:aux-as-list obj)
		 ,@(sxml:content obj)
		 )))
	(else #f)))))
    
; Change value of the attribute for element <obj> 
; <attr> is (<attr-name> <attr-value>)
; Returns #f if where is no such attribute
(define (sxml:change-attr! obj attr)
  (let ((x (sxml:attr-list obj)))
     (if (null? x)
       #f
       (cond 
	 ((assv (car attr) x) => (lambda (y)
				  (set-cdr! y (cdr attr)) obj))
	 (else #f)))))

; Set attribute <attr> of element <obj> 
; If there is no such attribute the new one is added
(define (sxml:set-attr obj attr)
  (let ((attr-list (sxml:attr-list obj)))
    (cond 
      ((assv (car attr) attr-list) 
       => (lambda (y)
	    `(,(sxml:name obj)
	       (% ,@(map
		      (lambda(at)
			(if
			  (eq? at y)
			  attr
			  at))
		      attr-list))
	       ,@(sxml:aux-as-list obj)
	       ,@(sxml:content obj)
	       )))
      (else 
	`(,(sxml:name obj)
	   (% ,@(cons attr attr-list)) 
	   ,@(sxml:aux-as-list obj)
	   ,@(sxml:content obj))))
    ))

; Set attribute <attr> of element <obj> 
; If there is no such attribute the new one is added
(define (sxml:set-attr! obj attr)
  (let ((attr-list (sxml:attr-list obj)))
     (cond 
       ((assv (car attr) attr-list) 
	=> (lambda (x) (set-cdr! x (cdr attr))))
       (else (set-cdr! obj
		       `((% ,@(cons attr attr-list)) 
			 ,@(sxml:aux-as-list obj)
			 ,@(sxml:content obj))))
   )))

; Returns SXML element <obj> with an auxiliary node <aux-node> added 
(define (sxml:add-aux obj aux-node)
      `(,(sxml:name obj)
	(% ,@(sxml:attr-list obj))
	(%% ,@(cons aux-node (sxml:aux-list obj)))
	,@(sxml:content obj)))

; Add an auxiliary node <aux-node> for an element <obj>
(define (sxml:add-aux! obj aux-node)
      (set-cdr! obj 
	`(
	(% ,@(sxml:attr-list obj))
	(%% ,@(cons aux-node (sxml:aux-list obj)))
	,@(sxml:content obj)))
      obj)

; Eliminates empty lists of attributes and aux-lists for given SXML element 
; <obj> and its descendants ("minimize" it)
; Returns: minimized and normalized SXML element
(define (sxml:squeeze! obj)
   (set-cdr! obj 
  `(,@(cond 
	((sxml:attr-list-node obj)
	 => (lambda (atl) 
	      (if (and (null? (cdr atl)) 
		       (null? (sxml:aux-list obj)))
		 '()
	         (list atl))))	
	(else '()))
    ,@(cond ((sxml:aux-list-node obj)
	     => (lambda (axl) 
	      (if (null? (cdr axl))
		'()
	         (list axl))))
	(else '()))
    ,@(map
	(lambda(x)
	  (cond 
	    (((ntype?? '*) x)
	     (sxml:squeeze! x)
	     x)
	    (else x)))
       (sxml:content obj))
    ))
   )

	     
; Eliminates empty lists of attributes and aux-lists for given SXML element 
; <obj> and its descendants ("minimize" it)
; Returns: minimized and normalized SXML element
(define (sxml:squeeze obj)
  `(,(sxml:name obj)
   ,@(cond 
	((sxml:attr-list-node obj)
	 => (lambda (atl) 
	      (if (and (null? (cdr atl)) 
		       (null? (sxml:aux-list obj)))
		 '()
	         (list atl))))	
	(else '()))
    ,@(cond ((sxml:aux-list-node obj)
	     => (lambda (axl) 
	      (if (null? (cdr axl))
		'()
	         (list axl))))
	(else '()))
    ,@(map
	(lambda(x)
	  (cond 
	    (((ntype?? '*) x)
	     (sxml:squeeze x))
	    (else x)))
       (sxml:content obj))))

; Eliminates empty lists of attributes and ALL aux-lists for given SXML element 
; <obj> and its descendants
; Returns: minimized and normalized SXML element
(define (sxml:clean obj)
  `(,(sxml:name obj)
   ,@(cond 
	((sxml:attr-list-node obj)
	 => (lambda (atl) 
	      (if (null? (cdr atl)) 
		 '()
	         (list atl))))	
	(else '()))
    ,@(map
	(lambda(x)
	  (cond 
	    (((ntype?? '*) x)
	     (sxml:clean x))
	    (else x)))
       (sxml:content obj))))
;==============================================================================
; SXPath-related 

;------------------------------------------------------------------------------
; Extensions

; select-first-kid:: Pred -> Node -> Node
; Given a Node, return its first child that satisfy
; the test-pred?
; Returns #f if there is no such a child
; select-first-kid:: Pred -> Nodeset -> Node
; The same as above, but select among children of all the nodes in
; the Nodeset
(define (select-first-kid test-pred?)
 (lambda(obj)
  (let rpt ((lst (if (symbol? (car obj)) 
		  (cdr obj)
		  obj)))
    (cond 
      ((null? lst) #f)
      ((and (pair? (car lst))
	    (test-pred? (car lst)))
	(car lst))
      (else (rpt (cdr lst)))) 
    )))

;------------------------------------------------------------------------------
; Fast node-parent 

; Returns a function of one argument - SXML element - which returns its parent
; node using *PARENT* pointer in aux-list
; '*TOP-PTR* may be used as a pointer to root node
; It return an empty list when applyed to root node
(define (sxml:node-parent rootnode)
  (lambda(obj)
  (cond 
    ((sxml:aux-node obj '*PARENT*)
     => (lambda(x)
 	  (if 
 	    (eq? '*TOP-PTR* (cadr x))
	  rootnode
	  ((cadr x)))))
    ((and (pair? obj)
          (eq? (car obj) '*TOP* ))
     '())           
     (else (sxml:error nl "PARENT pointer is absent in: " obj nl)
	   ))))

(define (sxml:add-parents obj . top-ptr)
  (let rpt 
    ((elt obj)
     (p '*TOP*)
     (at-aux (if (eq? (sxml:name obj) '*TOP*)
		(list (cons '%% (sxml:aux-list-u obj)))
		(list
		  (cons '% (sxml:attr-list obj))
		  (cons '%% (cons `(*PARENT* ,(lambda() (car top-ptr))) 
						 (sxml:aux-list obj))))))
     ) ; *TOP* is a parent for top-level element
    (let* ((h (list (sxml:name elt)))
	   (b  (append 
		 at-aux
		 (map
		     (lambda(x)
		       (cond 
			 (((ntype?? '*) x)
			  (rpt x h
			       (list
				 (cons '% (sxml:attr-list x))
				 (cons '%% (cons `(*PARENT* ,(lambda() h)) 
						 (sxml:aux-list x))))
			       ))
			 (else x)))
		     (sxml:content elt)))))
      (set-cdr! h b)
      h)))

; Lookup an element using its ID 
(define (sxml:lookup id index)
    (cond
      ((assoc id index) 
       => cdr)
      (else #f)))

;==============================================================================
; Markup generation

;------------------------------------------------------------------------------
; XML

; Creates the XML markup for attributes.
(define (sxml:attr->xml attr)
   (list " " (sxml:ncname attr)
	 "='" (cadr attr) "'"))

; Return a string or a list of strings where all the occurences of 
; characters < > & " ' in a given string are replaced by corresponding 
; character entity references. See also:  sxml:string->html
(define sxml:string->xml
  (make-char-quotator
   '((#\< . "&lt;") (#\> . "&gt;") (#\& . "&amp;") 
		    (#\" . "&quot;") (#\' . "&apos;"))))

; A version of dispatch-node specialized and optimized for SXML->XML
; transformation.
(define (sxml:sxml->xml tree)
  (cond
    ((nodeset? tree)
     (map (lambda (a-tree) 
	    (sxml:sxml->xml a-tree)) 
	  tree))
    ((pair? tree)
     (let* ((name (sxml:name tree))   ; NS (URI-prefixed) not supported
	    (nm (symbol->string name))
	    (content (sxml:content-raw tree)))
	 `("<" ,nm ,@(map sxml:attr->xml (sxml:attr-list tree))
	   ,@(if (null? content) '("/>")
	       `(">" ,@(sxml:sxml->xml content) "</" ,nm ">")))))
    ((string? tree) (sxml:string->xml tree)) ; *text*
    (else (sxml:error "sxml->html - unexpected type of node: " tree))))


;------------------------------------------------------------------------------
; HTML

; Creates the HTML markup for attributes.
(define (sxml:attr->html attr)
	 (if (equal? "" (cadr attr))
             (list " " (sxml:ncname attr))
             (list " " (sxml:ncname attr) "='" (cadr attr) "'")))



; Given a string, check to make sure it does not contain characters
; < > & " that require encoding. Return either the original
; string, or a list of string fragments with special characters
; replaced by appropriate character entities.
; Borrowed from Oleg Kiselyov's XML-to-HTML.scm (where its name is
; string->goodHTML)
(define sxml:string->html
  (make-char-quotator
   '((#\< . "&lt;") (#\> . "&gt;") (#\& . "&amp;") (#\" . "&quot;"))))


; This predicate yields #t for "unterminated" HTML 4.0 tags
(define (sxml:non-terminated-html-tag? tag) 
  (memq tag 
     '(area base basefont br col frame hr img input isindex link meta param)))


; A version of dispatch-node specialized and optimized for SXML->HTML
; transformation.
(define (sxml:sxml->html tree)
  (cond
    ((nodeset? tree)
     (map (lambda (a-tree) 
	    (sxml:sxml->html a-tree)) 
	  tree))
    ((pair? tree)
     (let* ((name (sxml:name tree))
	    (nm (symbol->string name))
	    (content (sxml:content-raw tree)))
	 `("<" ,nm ,@(map sxml:attr->html (sxml:attr-list tree))
	   ,@(if (null? content)
	       (if (sxml:non-terminated-html-tag? name) '(">") '("/>"))
	       `(">" ,@(sxml:sxml->html content) "</" ,nm ">")))))
    ((string? tree) (sxml:string->html tree)) ; *text*
    (else (sxml:error "sxml->html - unexpected type of node: " tree))))