Re: Getting selected PCDATA

Subject: Re: Getting selected PCDATA
From: Ron Ross <ronross@xxxxxxxxx>
Date: 24 Sep 1999 15:28:17 -0400
Many thanks, Brandon.

I'm having some trouble in getting this script to work (just working
with the example DTD-instance bellow). 

When I run the script through OpenJade with the examples given, with the
RTF backend, I get an empty page. If I comment out either of the element
rules for PARENT or CHILD, I get partial results: i.e., if only the one
for PARENT is in effect, I get the data from CHILD; if the one for
CHILD, I get the PARENT data. Armed with the spec, I'm going to try to
understand exactly what's going on in the script, but if you've got a
clue for me to digest in the meantime . . .


BTW, I'm sorry it's taken a while for me to respond; I was *really*
under the gun for getting work out, didn't have time to look at the code
carefully and didn't want to send back a lame reply. Well, now I think
I'm sending one anyway;-(

On Tue, 21 Sep 1999, Brandon Ibach spake thusly:> 
> Content-Type: text/plain; charset=us-ascii
>    Okay... I accidentally deleted the original post before I was ready
> to respond to it, but this has to do with the question about selecting
> a portion of the PCDATA from a <parent> element within the rule for a
> <child> element.
>    Attached are a very simple document (including DTD) and a DSSSL
> stylesheet which uses the SGML backend's "formatting-instruction" FO
> to spit out the general structure of each <parent>'s content, then a
> single line for each <child> in that <parent>, listing the content of
> the child, an "=", and the immediately preceding "term" from the
> parent.  The "term", in this case, is the chunk of text leading up to
> the <child>, starting at either the beginning of the <parent> or the
> most recent comma.  Before being printed, it is trimmed of whitespace
> at the beginning and end.
>    Note that the function which finds the "term" (lastterm) actually
> accepts an optional singleton node list, which defaults to the current
> node.  So, you could actually get the "term" preceding *any* node.
> It doesn't even have to be an element.
>    I hope the code will stand on its own and be clear enough, even
> though I didn't really document it.  Any questions, please ask. :)
> -Brandon :)
> Content-Type: text/x-sgml
> Content-Disposition: attachment; filename="dtest.sgml"
> <!doctype dtest [
> <!element dtest  o o (parent)*>
> <!element parent o o (#PCDATA|child)*>
> <!element child  - o (#PCDATA)*>
> ]>
> <parent>some text<child>some term</child>,
> other text<child>other term</child>, last text</parent>
> Content-Type: text/x-dsssl; charset=us-ascii
> Content-Disposition: attachment; filename="dtest.dsl"
> <!doctype style-sheet PUBLIC "-//James Clark//DTD DSSSL Style
> Sheet//EN">
> <style-specification>
> (declare-flow-object-class formatting-instruction
>   "UNREGISTERED::James Clark//Flow Object Class::formatting-instruction")
> (define cr (string #\U-000D #\U-000A))
> (define showkids (lambda (#!optional (nl (children (current-node))))
>   (let loop ((n nl) (s "") (d 0))
>     (if (node-list-empty? n) s
>       (let* ((cn (node-list-first n)) (c (node-property 'class-name cn)))
>         (loop (node-list-rest n)
>               (apply string-append
>                      (if (equal? 'data-char c)
>                          (list s (if (= d 0) "  Data: " "")
>                                (string (node-property 'char cn)))
>                          (list s (if (> d 0) cr "")
>                                (if (equal? 'element c)
>                                    "  Element: " "  Node: ")
>                                (if (equal? 'element c)
>                                    (gi cn) (symbol->string c))
>                                cr)))
>               (if (equal? 'data-char c) (+ d 1) 0)))))))
> (define node-list-contains? (lambda (nl snl)
>   (cond ((node-list-empty? nl) #f)
>         ((node-list=? snl (node-list-first nl)) #t)
>         (else (node-list-contains? (node-list-rest nl) snl)))))
> (define lastterm (lambda (#!optional (el (current-node))
>                                      (nl (children (parent (current-node)))))
>   (let loop ((n nl) (s ""))
>     (if (node-list-empty? n) ""
>       (let* ((cn (node-list-first n)))
>         (if (node-list-contains? el cn) s
>             (loop (node-list-rest n)
>                   (if (equal? 'data-char (node-property 'class-name cn))
>                       (let ((ch (string (node-property 'char cn))))
>                         (if (equal? "," ch) "" (string-append s ch)))
>                       s))))))))
> (define trim (lambda (s)
>   (let ((l (string-length s)))
>     (let loop ((i 0) (r "") (w ""))
>       (if (>= i l) r
>           (if (member (string-ref s i) '(#\space #\U-0009 #\U-000A #\U-000D))
>               (loop (+ i 1) r (string-append w (substring s i (+ i 1))))
>               (loop (+ i 1) (string-append r (if (< 0 (string-length r)) w "")
>                                            (substring s i (+ i 1))) "")))))))
> (element PARENT (sosofo-append
>   (make formatting-instruction
>         data: (string-append "Parent: " cr (showkids) cr))
>   (process-node-list (select-elements (children (current-node)) "CHILD"))))
> (element CHILD
>   (make formatting-instruction
>         data: (string-append "Child: " (data (current-node))
>                              " = " (trim (lastterm)) cr)))
> </style-specification>
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