[luatex] \Ucharcat

[Hans Hagen]

Hi David,

Here is a better example. Instead of directlua, we register a function 
and call that one. The funny expandafters make sure we call them 
out-of-order. It works ok in luatex-plain. In fact, \directlua itself 
could be reimplemented as function but it is slightly slower then so we 
keep it as core primitive.

(Btw, some day soon I'm going to see if some backend primitives can be 
replaced by directlua + tokenscanner calls). The smaller the core and 
the more decoupled the backend is from the scanner, the better.)

\directlua{
     gadgets = gadgets or { } % reserved namespace

     gadgets.functions = { }
     local registered  = { }

     function gadgets.functions.reserve()
         local numb = newtoken.scan_int()
         local name = newtoken.scan_string()
         local okay = string.gsub(name,"[\string\\ ]","")
         registered[okay] = numb
         texio.write_nl("reserving lua function '"..okay.."' with number 
"..numb)
     end

     function gadgets.functions.register(name,f)
         local okay = string.gsub(name,"[\string\\ ]","")
         local numb = registered[okay]
         if numb then
             texio.write_nl("registering lua function '"..okay.."' with 
number "..numb)
             lua.get_functions_table()[numb] = f
         else
             texio.write_nl("lua function '"..okay.."' is not reserved")
         end
     end

}

\newcount\lastallocatedluafunction

\def\newluafunction#1%
   {\ifdefined#1\else
      \global\advance\lastallocatedluafunction 1
      \global\chardef#1\lastallocatedluafunction
      \directlua{gadgets.functions.reserve()}#1{\detokenize{#1}}%
    \fi}

\newluafunction\UcharcatLuaOne
\newluafunction\UcharcatLuaTwo

\directlua {

     local cct = nil
     local chr = nil

     gadgets.functions.register("UcharcatLuaOne",function()
         chr = newtoken.scan_int()
         cct = tex.getcatcode(chr)
         tex.setcatcode(chr,newtoken.scan_int())
         tex.sprint(unicode.utf8.char(chr))
     end)

     gadgets.functions.register("UcharcatLuaTwo",function()
         tex.setcatcode(chr,cct)
     end)

}

\def\Ucharcat
   {\expandafter\expandafter\expandafter\luafunction
    \expandafter\expandafter\expandafter\UcharcatLuaTwo
    \luafunction\UcharcatLuaOne}

A:\the\catcode65:\Ucharcat 65 11:A:\the\catcode65\par
A:\the\catcode65:\Ucharcat 65  5:A:\the\catcode65\par
A:\the\catcode65:\Ucharcat 65 11:A:\the\catcode65\par

Hans

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                                           Hans Hagen | PRAGMA ADE
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