Re: [NTG-context] supp-ran.lua makes code unable to work in ConTeXt

[Hans Hagen]

On 5/1/2020 6:12 AM, Jairo A. del Rio wrote:

I've adapted the following code to make mazes in LuaLaTeX and ConTeXt: https://www.rosettacode.org/wiki/Maze_generation#Lua

function make_maze_tex(w, h, m)
   w = w or 16
   h = h or 8

   local map = initialize_grid(w*2+1, h*2+1)

   function walk(x, y)
     map[y][x] = false

     local d = { 1, 2, 3, 4 }
     shuffle(d)
     for i, dirnum in ipairs(d) do
       local xx = x + dirs[dirnum].x
       local yy = y + dirs[dirnum].y
       if map[yy] and map[yy][xx] then
         map[avg(y, yy)][avg(x, xx)] = false
         walk(xx, yy)
       end
     end
   end

   walk(math.random(1, w)*2, math.random(1, h)*2)

  tex.print([[\bgroup]])
  tex.print([[\baselineskip ]]..m)
   local s = {}
   for i = 1, h*2+1 do
     --table.insert(s, [[\hbox{]])
     tex.print([[\hbox{]])
     for j = 1, w*2+1 do
      -- table.insert(s, [[\hbox{]])
       if (j == 1 and i == 2) or (j == 2*w + 1 and i == 2*h) then
         tex.print([[\hskip ]]..m)
       elseif map[i][j] then
         --table.insert(s, [[\vrule width ]]..m..[[ height ]]..m)
         tex.print([[\vrule width ]]..m..[[ height ]]..m)
       else
         --table.insert(s, [[\hskip ]]..m)
         tex.print([[\hskip ]]..m)
       end
     --  table.insert(s, [[}]].."\n")
     end
     --table.insert(s, [[}]])
   tex.print([[}]])
   end
  --tex.print(table.concat(s))
  tex.print([[\egroup]])
end

And I executed the folowing in LuaLaTeX and ConTeXt:

%\documentclass{article}
%\usepackage{luacode}
%\begin{document}
\starttext
%\begin{luacode*}
\startluacode
mz = dofile("maze.lua")
local count = 0
for i=10,109 do
count = count + 1
tex.print([[\subject{Laberinto ]]..count..[[}]])
mz.make_maze_tex(i, i, [[\dimexpr\textwidth/]]..(2*i+1)..[[\relax]])
tex.print([[\pagebreak]])
end
%\end{luacode*}
\stopluacode
%\end{document}
\stoptext

I defined a modified version to make content visible to TeX and I saved in a file named maze.lua: Whereas it works very fast in LuaLaTeX it crashes on ConTeXt and outputs the following:

btw, fast is relative ... no problem making the code twice as fast

it is actually a nice example for the cld manual ... attached some output from a first 'improvement' (that version runs some 50-60% faster so you have a challenge ... actually, it could be a nice challenge for others on this list: how to make this one contextish and so, maybe we should have a challenge every few weeks)

token call, execute: ...ext/tex/texmf-context/tex/context/base/mkiv/supp-ran.lua:30: C stack overflow Why does it happen? I guess it has something to do with math.randomseed, but I don't know how to avoid this error message.

no, it's just lua running out of stack space so it depends on the binary (and als the initial random value)

luajittex has a limited stack of 8000 so it will also crash



(new lmtx upload later this weekend)

Hans

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                                          Hans Hagen | PRAGMA ADE
              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
       tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl
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luatex 1.13 uses lua 5.3 which has a large stack but depending on the compiler/linker settings and platform (it's 1000000 but depending on the situatation you get a message or crash when that doesn't work out) luametatex uses lua 5.4 which uses a bit different stack model and can't go that high (it has a default of 2000 but i will bnump that to 6000 which still seems to work ok, that way i get upto a 120 maze)

mazecontext.pdf
Description: Adobe PDF document

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