Here is a proof of concept at doing the equivalent of \XeTeXinterchartoks in luatex.
First, a style file:
% luatexinterchartoks.sty
\newcount\XeTeXinterchartokenstate
\newcount\charclasses
\def\newXeTeXintercharclass#1%
{\global\advance\charclasses1\relax
\newcount#1
\global#1=\the\charclasses
}
\newcount\cchone
\newcount\cchtwo
\def\dodoXeTeXcharclass
{\directlua{setcharclass(\the\cchone,\the\cchtwo)}}
\def\doXeTeXcharclass%
{\afterassignment\dodoXeTeXcharclass\cchtwo }
\def\XeTeXcharclass%
{\afterassignment\doXeTeXcharclass\cchone }
\protected\def\XeTeXdointerchartoks%
{\directlua{setinterchartoks(\the\cchone,\the\cchtwo,\the\allocationnumber)}}
\protected\def\dodoXeTeXinterchartoks%
{\newtoks\mytoks\afterassignment\XeTeXdointerchartoks\global\mytoks }
\protected\def\doXeTeXinterchartoks%
{\afterassignment\dodoXeTeXinterchartoks\cchtwo }
\def\XeTeXinterchartoks%
{\afterassignment\doXeTeXinterchartoks\cchone }
\luatexdirectlua{dofile('luatexinterchartoks.lua')}
\endinput
And a matching lua file:
% luatexinterchartoks.lua
charclasses = charclasses or {}
function setcharclass (a,b)
charclasses[a] = b
end
local i = 0
while i < 65536 do
charclasses[i] = 0
i = i + 1
end
interchartoks = interchartoks or {}
function setinterchartoks (a,b,c)
interchartoks[a] = interchartoks[a] or {}
interchartoks[a][b] = c
end
local nc, oc
oc = 255
function do_intertoks ()
local tok = token.get_next()
if tex.count['XeTeXinterchartokenstate'] == 1 then
if tok[1] == 11 or tok[1] == 12 then
nc = charclasses[tok[2]]
newchar = tok[2]
else
nc = 255
newchar = ''
end
local insert = ''
if interchartoks[oc] and interchartoks[oc][nc] then
insert = interchartoks[oc][nc]
local newtok = tok
if insert<100 then
local dec = math.floor(insert / 10) + 48;
local unit = math.floor(insert % 10) + 48;
newtok = {
-- \XeTeXinterchartokenstate=0 \the\toks<n> \XeTeXinterchartokenstate=1
token.create('XeTeXinterchartokenstate'),
token.create(string.byte('='),12),
token.create(string.byte('0'),12),
token.create(string.byte(' '),10),
token.create('the'),
token.create('toks'),
token.create(dec,12),
token.create(unit,12),
token.create(string.byte(' '),10),
token.create('XeTeXinterchartokenstate'),
token.create(string.byte('='),12),
token.create(string.byte('1'),12),
token.create(string.byte(' '),10),
{tok[1], tok[2], tok[3]}}
end
tok = newtok
end
oc = nc
end
return tok
end
callback.register ('token_filter', do_intertoks)
And a test document:
\documentclass{article}
\usepackage{luatexinterchartoks}
\usepackage{color}
\begin{document}
\newXeTeXintercharclass \mycharclassa
\newXeTeXintercharclass \mycharclassA
\newXeTeXintercharclass \mycharclassB
\XeTeXcharclass `\a \mycharclassa
\XeTeXcharclass `\A \mycharclassA
\XeTeXcharclass `\B \mycharclassB
% between "a" and "A":
\XeTeXinterchartoks \mycharclassa \mycharclassA = {[\itshape}
\XeTeXinterchartoks \mycharclassA \mycharclassa = {\upshape]}
% between " " and "B":
\XeTeXinterchartoks 255 \mycharclassB = {\bgroup\color{blue}}
\XeTeXinterchartoks \mycharclassB 255 = {\egroup}
% between "B" and "B":
\XeTeXinterchartoks \mycharclassB \mycharclassB = {.}
\begingroup
\XeTeXinterchartokenstate = 1
aAa A a B aBa BB
\endgroup
\end{document}
Not very pretty, but it proves that it can be done ...
Best Answer
Verbatim text uses the font defined with
\setmonofont(or the default Latin Modern Typewriter font).However, when the Greek language is active, Polyglossia makes XeLaTeX look whether the font has the GRK feature and, if that's not available, it looks whether a font family under the name
\greekfonttthas been defined. Thus(use your preferred monospaced font) should do.
I wouldn't use
ucharclassesfor switching automatically from English to Greek and conversely: this will fill your auxiliary files with\select@languagedeclarations and won't ensure that a monospaced font is used inverbatim. Rather prefer the standard method of confining language switches with explicit\selectlanguagecommands (not recommended),otherlanguage,otherlanguage*or\foreignlanguage.