Re: [xsl] Help With Homework: HTML Tables to CALS

["David Birnbaum djbpitt@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Dear Martin and Michael,

Thank you both for the quick responses!

Best,

David

On Thu, Jan 23, 2020 at 12:38 PM Michael Kay mike@xxxxxxxxxxxx <
xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:

> In Saxon there's the vendor extension <xsl:function
> saxon:memo-function="yes"/> which has been available for some years; in
> XSLT 3.0 it's standardised as <xsl:function cache="yes"/>
>
> Michael Kay
> Saxonica
>
> On 23 Jan 2020, at 17:31, David Birnbaum djbpitt@xxxxxxxxx <
> xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Dear XSL-list,
>
> Is there information anywhere about how to construct a memo function? I
> see that support for it it is built into Saxon PE and EE, but does anyone
> know of an example or description of how to construct a memo function in
> HE, or a different XSLT engine that does already incorporate hooks for that
> functionality?
>
> Thanks,
>
> David
>
> On Thu, Jan 23, 2020 at 11:15 AM Michael Kay mike@xxxxxxxxxxxx <
> xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
>> One technique I have found useful in converting algorithms designed for
>> procedural programming languages is to use memo functions. For example, if
>> you need to assign  (row, column, height, depth) properties to every cell
>> in a table, you don't necessarily need to construct a data structure
>> holding that information; if you have a function (or set of functions)
that
>> computes the properties in terms of the corresponding properties for other
>> cells in the table, and if you make that computation a memo function, then
>> the data structure is there in the implicit memory of the memo function,
>> and doesn't need to be exposed explicitly in variables. To take an example
>> with a one-dimensional table where every cell has a colspan attribute, we
>> can compute
>>
>> function f:column($cell) { $cell ! (if (preceding-sibling::cell) then
>> (column(preceding-sibling::cell) + (@colspan, 1)[1]) else 1) }
>>
>> and if this is a memo function, we don't need to worry about the cost of
>> repeated computation of the function.
>>
>> Michael Kay
>> Saxonica
>>
>> On 23 Jan 2020, at 15:59, Eliot Kimber ekimber@xxxxxxxxxxxx <
>> xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>> Andrew's code will almost certainly allow me to solve my immediate
>> problem.
>>
>> I would still be interested in an XSLT 3 solution that uses arrays or
>> maps, but I might be able to work it out myself, although I know that I
>> don't fully grok the best/most compact way to do things, for example,
>> taking advantage of higher-order functions or fold-* approaches.
>>
>> Cheers,
>>
>> E.
>> --
>> Eliot Kimber
>> http://contrext.com
>>
>>
>> o;?On 1/23/20, 9:37 AM, "Martin Honnen martin.honnen@xxxxxx" <
>> xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>>
>>    Am 23.01.2020 um 16:30 schrieb Eliot Kimber ekimber@xxxxxxxxxxxx:
>>
>> I have XSLT 1-style code that converts HTML tables to CALS tables. I
>> discovered that this code fails for certain patterns of HTML tables in
that
>> it miscalculates column spans in the face of row spans earlier in the
>> table. It doesn't fail for all tables, just specific ones (which is why we
>> didn't notice this bug earlier). I haven't been able to determine the
cause
>> of the bug in the short time I've had to debug it (found the bug in the
>> course of trying to prepare a rush publishing job that has about 50
complex
>> tables in it, of course).
>>
>> Rather than try to debug and fix the XSLT 1 solution it seemed easier and
>> better to re-implement the processing using XSLT 3 and I took a stab at
>> doing it using arrays last night, but quickly got bogged down in my own
>> lack of facility with such things. The procedural solution in i.e., Java,
>> would be easy: just populate the 2x2 matrix that represents the table grid
>> to reflect row and column spans as you process the table cells
>> left-to-right and top to bottom, using cells projected from earlier rows
to
>> determine the starting column of cells in subsequent rows that get pushed
>> over by row-spanning cells.
>>
>> However, I couldn't quickly see how to do this using arrays or maps in
>> XSLT 3--the immutability of arrays and thus the coding patterns that take
>> existing arrays or maps and return new ones threw me and my feeble brain
>> just wasn't landing on the right algorithmic pattern.
>>
>> I know there must be a general pattern for this type of processing but
>> none of the examples I could find were helpful.
>>
>> So my request: can someone help me with this challenge and outline how to
>> solve this kind of problem where you take as input an HTML table where any
>> cell may span two or more columns and two or more rows and produce a 2x2
>> array representing the table's grid, where every grid cell reflects the
>> HTML table cell that covers it.
>>
>> From that array it's then easy to determine what the CALS result should
>> be (where CALS represents column spans by naming the start and end columns
>> the cell spans).
>>
>>
>>    Does Andrew's XSLT 2 code help?
>>    http://andrewjwelch.com/code/xslt/table/table-normalization.html
>>
>>
>>
>>
>>
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