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% This is the macro package used by OpTeX, see http://petr.olsak.net/optex
% vlna.opm, Petr Olšák <petr@olsak.net>, 2021
% Vlna prevents breaks in spaces after single-letter prepositions, after (or
% before) degrees, and between value and SI units. It enables or disables
% split hyphens too. All folks are done at the postprocessing phase before TeX splits
% the typesetting material into the paragraph lines.
% vlna.opm is based on Lua code from the package `luavlna` (by Michal Hoftich
% and Miro Hrončok). See `texdoc luavlna` or end of this file for more information.
\_codedecl \singlechars {Preventing single-chars prepositions and more <2021-01-08>}
\_namespace{vlna}
\_doc -----------------------------
We declare new attribute, register callbacks, and define Lua functions that
point to Lua functions from `luavlna.lua` package.
We need this package installed.
We need not `require ltluatex` because `luatexbase.callbaks` are defined
in the `optex.lua` file and it is part of the OpTeX format.
\_cod -----------------------------
\_newattribute \.preventsinglestatus
\_directlua{%
luavlna = require "luavlna"
luatexbase.add_to_callback("pre_linebreak_filter", luavlna.preventsingle,"LuaVlna")
luatexbase.add_to_callback("hyphenate", luavlna.split_hyphens, "allow hyphen breaks")
luavlna.preventsingleid = \_the\_attributealloc
set_singlechars = function(lang,chars)
if (lang == "") then return nil end
local utf_gmatch = unicode.utf8.gmatch
local chars = chars or ""
local singlechars = {}
for char in unicode.utf8.gmatch(chars,"(\_csstring\%a)") do
singlechars[char] = true
end
luavlna.singlechars(lang,singlechars)
end
set_compounds = function(lang, compounds)
if (lang == "") then return nil end
local c = compounds:explode(",+") % match multiple colons as one
local compoundstable = {}
for _, compound in pairs(c) do
compoundstable[compound] = true
end
luavlna.initials(lang, compoundstable)
end
set_main_language = function(lang)
if (lang == "") then return nil end
luavlna.set_main_language(tonumber(lang))
end
enable_split_hyphens = function(lang)
if (lang == "") then return nil end
luavlna.split_hyphen_langs[tonumber(lang)] = true
end
disable_split_hyphens = function(lang)
if (lang == "") then return nil end
luavlna.split_hyphen_langs[tonumber(lang)] = nil
end
}
\_doc -----------------------------
We need not `require luavlna-langno` because of the conversion from
language name to the `\language` number is done by the macro
`\.langtonum``<sequence>={<langname>}` defined here.
It does `\def<sequence>{<langnumber>}` or `\def\sequence{}` if <langname>
is unknown. The <langname> is case insensitive and these names are
declared in the hyphen-lan.opm file, section 2.37.2 in OpTeX documentation.
\_cod -----------------------------
\_def\.langtonum#1=#2{\_lowercase{\_edef#1{\_trycs{_ulan:#2}{}}}%
\_ifx#1\_empty \_opwarning{vlna: unknown language "#2", ignored}%
\_else \_edef#1{\_the\_cs{_#1Patt}}\_fi}
\_doc -----------------------------
`\singlechars``{<langname>}{<prepositions>}` sets <prepositions> for
given language.\nl
`\compoundinitials``{<langname>}{<comma-separated-list>}` sets
compound characters from the list for given language.
\_cod -----------------------------
\_def\.singlechars#1#2{\.langtonum\.l={#1}\_directlua{set_singlechars("\.l","#2")}}
\_def\.compoundinitials#1#2{\.langtonum\.l={#1}\_directlua{set_compounds("\.l","#2")}}
\_doc -----------------------------
`\enablesplithyphens` and `\disablesplithyphens` are dependent on the language.
\_cod -----------------------------
\_def\.enablesplithyphens#1{\.langtonum\.l={#1}\_directlua{enable_split_hyphens("\.l")}}
\_def\.disablesplithyphens#1{\.langtonum\.l={#1}\_directlua{disable_split_hyphens("\.l")}}
\_doc -----------------------------
By default, the language-dependent features of the `luavlna` depend on
the current `\language` value, i.e. on the currently selected hyphenation.
`\preventsinglelang``{<langname>}` activates the language-dependent
features regardless of the current `\language` value.
\_cod -----------------------------
\_def\.preventsinglelang#1{\.langtonum\.l={#1}\_directlua{set_main_language("\.l")}}
\_doc -----------------------------
Switching on/off `luavlna` preposition features should be done using attribute
setting. It will allow you to switch them on/off in the middle of the paragraph.
\_cod -----------------------------
\_def\.preventsingleon{\.preventsinglestatus=2 }
\_def\.preventsingleoff{\.preventsinglestatus=1 }
\_doc -----------------------------
Switching on/off the other `luavlna` features is implemented only by
setting a special `luavlna` variable.
\_cod -----------------------------
\_def\.preventsingledebugon{\_directlua{luavlna.debug(true)}}
\_def\.preventsingledebugoff{\_directlua{luavlna.debug(false)}}
\_def\.nopredegrees{\_directlua{luavlna.no_predegrees = true}}
\_def\.nosufdegrees{\_directlua{luavlna.no_sufdegrees = true}}
\_def\.nounits{\_directlua{luavlna.no_unit = true}}
\_def\.noinitials{\_directlua{luavlna.no_initials = true}}
\_nspublic
\singlechars % declare single-letter prepositions per language
\compoundinitials % declare compound characters per language
\enablesplithyphens % enable split hyphens per language
\disablesplithyphens % disable split hyphens per language
\preventsinglelang % declare main language independent of current hyphenation
\preventsingleon % switch on the prepositions feature (default)
\preventsingleoff % switch off the prepositions feature
\nopredegrees % switch off pre-degrees feature (default is on)
\nosufdegrees % switch off post-degrees feature (default is on)
\nounits % switch off SI units feature (default is on)
\noinitials % switch off initials feature (default is on)
\preventsingledebugon % switch on debug printing (purple squares)
\preventsingledebugoff % switch off debug printing (default)
;
\_endnamespace
% Default values:
\singlechars{Czech}{AIiVvOoUuSsZzKk}
\singlechars{Slovak}{AIiVvOoUuSsZzKk}
\compoundinitials{Czech}{Ch,CH} % doesn't work in version v0.1g of luavlna
\enablesplithyphens{Czech}
\enablesplithyphens{Slovak}
% + predegrees, sufdegrees, units, initials (they are independent of language value)
\_endcode
What should be done automatically after `\load[vlna]`:
Prepositions feature: v lese -> v~lese, (A taky zde) -> (A~taky zde).
Pre-degrees feature: Mgr. Bown -> Mgr.~Brown.
Post-degrees feature: John Brown, PhD. -> John Brown,~PhD.
SI units feature: 42 cm -> 42~cm (with thin space)
Initials feature: J. Brown -> J.~Brown
Split hyphens feature: propan-butan -> propan\discretionary{-}{-}{-}butan.
The prepositions and split-hyphens features are language-dependent, the other
features are language-independent.
A testing file:
\begtt
\load[vlna]
\fontfam[LMfonts]
\cslang
\preventsingledebugon
Mgr. J. Brown, PhD., zkusí v lese (A taky v závorce) zkontrolovat rozměr 42 m.
Obejde se bez propan-butanových lahví.
\bye
\endtt
Note, that versinon v0.1g 2020-06-02 of the luavlna package is an
experimental code. It seems that `\compoundinitials` does not work in this
version and when you use `\hbox{-}` in a paragraph when
`\enablesplithyphens` then LuaTeX hangs.
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