[NTG-context] Re: How can a macro check how many items are in a list?

[Hans Hagen via ntg-context <ntg-context@ntg.nl>]

On 11/3/2024 5:53 PM, Bruce Horrocks wrote:
> \definecounter [MyItemsCounter]
> \definecounter [MyItemsUniqueID] [way=bytext]
> \setcounter    [MyItemsUniqueID] [1]
> 
> \definedataset [MyItems] [delay=yes]
> 
> \defineitemgroup [MyItems]
> \setupitemgroup  [MyItems]
>    [ before={\setcounter[MyItemsCounter][1]},
>      inbetween={\incrementcounter[MyItemsCounter]},
>      after={\setdataset[MyItems][\rawcountervalue[MyItemsUniqueID]][count=\rawcountervalue[MyItemsCounter]]%
>             \incrementcounter[MyItemsUniqueID]},
>    ]
> 
> \define\listLen{\datasetvariable{MyItems}{\rawcountervalue[MyItemsUniqueID]}{count}}
> \define\itemOrItems{\doifelse{\datasetvariable{MyItems}{\rawcountervalue[MyItemsUniqueID]}{count}}{1}{item}{items}}
> 
> \starttext
> 
> This list has \listLen\ \itemOrItems.
> \startMyItems
> \item cat
> \item dog
> \item tree
> \stopMyItems
> 
> \blank
> 
> This list has \listLen\ \itemOrItems.
> \startMyItems
> \item cow
> \stopMyItems
> 
> \stoptext

There is actually some info when you are in an itemize:

\currentitemindex
\currentnofitems

So it's not too hard to get the upcoming value of \currentnofitems:

(1) an extra helper in strc-itm.mkxl

\permanent\tolerant\protected\def\upcomingnofitems[#1]%
   {\the\numexpr
      \clf_analyzeupcomingitemgroup
        {\ifempty{#1}\v!itemize\else#1\fi}%
        \numexpr\c_strc_itemgroups_nesting+\plusone\relax
      \c_strc_itemgroups_max_items
    \relax}

(2) a few line patch in strc-itm.lmt

local function analyzeitemgroup(name,level,upcoming)
     local n = counts[name]
     local u = false
     if level == 1 then
         n = n + 1
         counts[name] = n
         u = upcoming and true
     end
     local items = 0
     local width = 0
     local itemgroup = collected[name]
     if itemgroup then
         local entry = itemgroup[n]
         if entry then
             local l = entry[level]
             if l then
                 items = l[1] or 0
                 width = l[2] or 0
             end
         end
     end
     if u then
         counts[name] = n - 1
     end
     texsetcount(c_strc_itemgroups_max_items,items)
     texsetdimen(d_strc_itemgroups_max_width,width)
end

plus extra:

implement {
     name      = "analyzeupcomingitemgroup",
     actions   = analyzeitemgroup,
     arguments = { "string", "integer", true }
}

And then for Bruce to come up with the singular / plural variant for

This list has \upcomingnofitems[MyItems] entries

\startMyItems
\item cat
\item dog
\item tree
\stopMyItems

This list has \upcomingnofitems\ entries

\startitemize
\item cat
\item dog
\item tree
\stopitemize


Hans


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                                           Hans Hagen | PRAGMA ADE
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