Re: Referring to multiple elements

[Sietse Brouwer <sbbrouwer@gmail.com>]

Hi Marco,

The heart of what you need is a lua function that will take an array
of numbers, and return an array of consective-number runs, like so:

fignumarray = {1, 2, 3,    5, 6,    8,   10, 11, 12}
-- figruns = get_runs(fignumarray)
-- returns a table structured like so:
--> figruns[1].start = 1, figruns[1].stop = 3,
--> figruns[2].start = 5, figruns[2].stop = 6,
--> figruns[3].start = 8, figruns[3].stop = 8,
--> figruns[4].start = 10, figruns[4].stop = 12

I've written one below, plus the scaffolding required to feed it the
right input, and print its output to ConTeXt. Only two functions still
need writing --- one to turn the context argument [fig:f1, fig:f2,
fig:f4] into a lua array of strings, and one to turn each reference
string into a figure number. But this should get you on your way.

If you're not comfortable with programming LuaTeX, say so and I can
fill in the two missing functions sometime this weekend. But they
should be doable, really. (And, of course, you may be far more
experienced in LuaTeX than I, I don't know.)

Cheers,
Sietse

% should be below startluacode block, but clearer like so
\def\inwithranges[#1]%
    {\ctxlua{u.inwithranges("#1")}}

\startluacode
u = userdata or { }

function get_runs(a)
    runs = { }
    run_start = 1
    while run_start <= #a do
        run_stop = run_start
        while a[run_stop + 1] == a[run_stop] + 1 do
            run_stop = run_stop + 1
        end
        print(a[run_start] .. "-" .. a[run_stop])

        table.insert(runs, {["start"] = a[run_start],
                            ["stop"]   = a[run_stop]})
        run_start = run_stop + 1
    end
    return runs
end

function u.inwithranges(ref_string)
    -- CTX... means I expect ConTeXt already has this function in a
library somewhere
    local ref_array = CTXstring_to_array(refs_string)  --FIXME
    local ref_numbers = { }
    for _, v in ipairs(ref_array) do
        ref_numbers[i] = CTXref_to_fignumber(array)  --FIXME
    end
    ref_numbers.sort()
    runs = get_runs(ref_numbers)
    for i, run in ipairs(runs) do
        context.in( {run.start} )
        context("-")
        context.in( {run.stop} )
        if i < #runs then context(',') end
    end
end

\stopluacode
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