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|
-- Lua code for the selnolig package.
-- To be loaded with an instruction such as
-- \directlua{ require("selnolig.lua") }
-- from a (Lua)LaTeX .sty file.
--
-- Author: Mico Loretan (loretan dot mico at gmail dot com)
-- (with crucial contributions from Taco Hoekwater,
-- Patrick Gundlach, and Steffen Hildebrandt)
--
-- The entire selnolig package is placed under the terms
-- of the LaTeX Project Public License, version 1.3 or
-- later. (http://www.latex-project.org/lppl.txt).
-- It has the status "maintained".
selnolig = { }
selnolig.module = {
name = "selnolig",
version = "0.256",
date = "2015/10/26",
description = "Selective suppression of typographic ligatures",
author = "Mico Loretan",
copyright = "Mico Loretan",
license = "LPPL 1.3 or later"
}
debug=false -- default: don't output detailed information
-- Define variables corresponding to various text nodes;
-- cf. sections 8.1.2 and 8.1.4 of LuaTeX reference guide
local rule = node.id('rule')
local glue = node.id("glue") --
local kern = node.id('kern')
local glyph = node.id('glyph') --
local whatsit = node.id("whatsit") --
local userdefined
for n,v in pairs ( node.whatsits() ) do
if v == 'user_defined' then userdefined = n end
end
local identifier = 123456 -- any unique identifier
local noliga={}
local keepliga={} -- String -> Boolean
function debug_info(s)
if debug then
texio.write_nl(s)
end
end
local blocknode = node.new(whatsit, userdefined)
blocknode.type = 100
blocknode.user_id = identifier
local suppression_on = true -- if false, process_ligatures won't do anything
local prefix_length = function(word, byte)
return unicode.utf8.len( string.sub(word,0,byte) )
end
-- Problem: string.find and unicode.utf8.find return
-- the byte-position at which the pattern is found
-- instead of the character-position. Fix this by
-- providing a dedicated string search function.
local unicode_find = function(s, pattern, position)
-- Start by correcting the incoming position
if position ~= nil then
-- debug_info("Position: "..position)
sub = string.sub(s, 1, position)
position=position+string.len(sub) - unicode.utf8.len(sub)
-- debug_info("Corrected position: "..position)
end
-- Now execute find and fix it accordingly
byte_pos = unicode.utf8.find(s, pattern, position)
if byte_pos ~= nil then
-- "convert" byte_pos to "unicode_pos"
return unicode.utf8.len( string.sub(s, 1, byte_pos) )
else
return nil
end
end
function process_ligatures(nodes,tail)
if not suppression_on then
return -- suppression disabled
end
local s={}
local current_node=nodes
local build_liga_table = function(strlen,t)
local p={}
for i = 1, strlen do
p[i]=0
end
for k,v in pairs(t) do
-- debug_info("Match: "..v[3])
local c= unicode_find(noliga[v[3]],"|")
local correction=1
while c~=nil do
--debug_info("Position "..(v[1]+c))
p[v[1]+c-correction] = 1
c = unicode_find(noliga[v[3]],"|",c+1)
correction = correction+1
end
end
--debug_info("Liga table: "..table.concat(p, ""))
return p
end
local apply_ligatures=function(head,ligatures)
local i=1
local hh=head
local last=node.tail(head)
for curr in node.traverse_id(glyph,head) do
if ligatures[i]==1 then
debug_info("Inserting nolig whatsit before glyph: " ..unicode.utf8.char(curr.char))
node.insert_before(hh,curr, node.copy(blocknode))
hh=curr
end
last=curr
if i==#ligatures then
-- debug_info("Leave node list on position: "..i)
break
end
i=i+1
end
if(last~=nil) then
debug_info("Last char: "..unicode.utf8.char(last.char))
end
end
for t in node.traverse(nodes) do
if t.id==glyph then
s[#s+1]=unicode.utf8.char(t.char)
end
if ( t.id==glue or t.next==nil or t.id==kern or t.id==rule ) then
local f=string.gsub(table.concat(s,""),"[\\?!,\\.]+","")
local throwliga={}
for k,v in pairs (noliga) do
local count=1
local match = string.find(f,k)
while match do
count = match
keep = false
debug_k1 = ""
for k1,v1 in pairs (keepliga) do
if v1 and string.find(f,k1) and string.find(k1,k) then
debug_k1=k1
keep=true
break
end
end
if not keep then
debug_info("pattern match: "..f .." - "..k)
local n = match + string.len(k) - 1
table.insert(throwliga,{prefix_length(f,match),n,k})
else
debug_info("pattern match nolig and keeplig: "..f .." - "..k.." - "..debug_k1)
end
match= string.find(f,k,count+1)
end
end
if #throwliga==0 then
-- debug_info("No ligature suppression for: "..f)
else
debug_info("Do ligature suppression for: "..f)
local ligabreaks = build_liga_table(f:len(),throwliga)
apply_ligatures(current_node,ligabreaks)
end
s = {}
current_node = t
end
end
end -- end of function process_ligatures(nodes,tail)
function suppress_liga(s,t)
noliga[s] = t
end
function always_keep_liga(s)
keepliga[s] = true
end
function enable_suppression(val)
suppression_on = val
if val then
debug_info("Turning ligature suppression back on")
else
debug_info("Turning ligature suppression off")
end
end
function enableselnolig()
luatexbase.add_to_callback( "ligaturing",
process_ligatures, "Suppress ligatures selectively", 1 )
end
function disableselnolig()
luatexbase.remove_from_callback( "ligaturing",
"Suppress ligatures selectively" )
end
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