Re: Best Way to Break Up Nested Structures Based On I

Gerrit,

I don't immediately see how the code in the referenced message works but it's
simple enough to try in my context.

In my case the number of switches is small relative to the total content, so
it will only be applied occasionally and infrequently.

Cheers,

E.

--
Eliot Kimber
http://contrext.com

o;?On 4/18/18, 1:15 PM, "Imsieke, Gerrit, le-tex gerrit.imsieke@xxxxxxxxx"
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:

    Hi Eliot,

    I think this can be tackled with what I call "upward projection", see
    for ex. https://markmail.org/message/kmq2g4fidmw6cofz

    You'd identify all leaf elements and group them (maybe a combination of
    group-starting-with="two-colum-start" and
    group-ending-with="two-colum-end" is in order here).

    Then for each group you transform the top-level block in a certain mode,
    with a tunneled parameter. The tunneled parameter contains the current
    group and its ancestors.

    In the template that matches any element in this mode, you check whether
    the tunneled parameter contains the current element. If so, the
    next-match identity template will apply, if not, nothing will be written
    to the result.

    There's a special template in this mode that matches the
    two-column-start element. It will create <fo:block span="none"> and then
    go on processing the children.

    I'm not 100% sure whether this works, but I have an intercontinental
    flight ahead of me. It will give me some time to create working code,
    unless you're faster implementing the suggested solution (or a better
one).

    I guess that the solution scales with the number of splitting points
    times the number of leaves, so performance may deteriorate for large
    documents with frequently changing column spans.

    Gerrit

    On 18/04/2018 19:45, Eliot Kimber ekimber@xxxxxxxxxxxx wrote:
    > Using XSLT 2 with Saxon.
    >
    > In the context of generating XSL-FO markup where there tree of fo:block
elements can be quite deep, I need to break the blocks into a sequence of
top-level blocks that specify @span based on the presence of markers anywhere
in the heirarchy. This is to support FOP's strict implementation of the FO
spec, which only allows specifying column spans on direct children of
fo:flow.
    >
    > In my processing I'm emitting marker elements to signal the starts and
ends of areas that need to change the column spanning, e.g.:
    >
    > <fo:block span="all">
    >    <fo:block>
    >       <fo:block>
    >         <fo:block>
    >            <two-column-start/>
    >        </fo:block>
    >        ...
    >       <two-column-end/>
    >     </fo:block>
    >    <fo:block>...
    >    </fo:block>
    > </fo:block>
    >
    > Where the result needs to be:
    >
    > <fo:block span="all">
    >     <!-- Stuff before two-column start -->
    > </fo:block>
    > <fo:block span="none">
    >     <!-- Stuff up to <two-column-end/> marker -->
    > </fo:block>
    > <fo:block span="all">
    >    <!-- Stuff after <two-column-end> marker -->
    > </fo:block>
    >
    > There must be a general pattern for solving this kind of transformation
pattern but I'm not seeing it or not remembering it.
    >
    > I can think of a recursive algorithm to do it but is there a simpler or
more efficient approach? Conceptually it's a for-each-group problem but the
structure of the content doesn't see to lend itself to grouping.
    >
    > Thanks,
    >
    > Eliot
    > --
    > Eliot Kimber
    > http://contrext.com
    >
    >
    >

    --
    Gerrit Imsieke
    GeschC$ftsfC<hrer / Managing Director
    le-tex publishing services GmbH
    Weissenfelser Str. 84, 04229 Leipzig, Germany
    Phone +49 341 355356 110, Fax +49 341 355356 510
    gerrit.imsieke@xxxxxxxxx, http://www.le-tex.de

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