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if not modules then modules = { } end modules ['font-imp-ligatures'] = {
version = 1.001,
comment = "companion to font-ini.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
local lpegmatch = lpeg.match
local utfsplit = utf.split
local settings_to_array = utilities.parsers.settings_to_array
local fonts = fonts
local otf = fonts.handlers.otf
local registerotffeature = otf.features.register
local addotffeature = otf.addfeature
-- This is a quick and dirty hack.
local lookups = { }
local protect = { }
local revert = { }
local zwjchar = 0x200C
local zwj = { zwjchar }
addotffeature {
name = "blockligatures",
type = "chainsubstitution",
nocheck = true, -- because there is no 0x200C in the font
prepend = true, -- make sure we do it early
future = true, -- avoid nilling due to no steps yet
lookups = {
{
type = "multiple",
data = lookups,
},
},
data = {
rules = protect,
}
}
addotffeature {
name = "blockligatures",
type = "chainsubstitution",
nocheck = true, -- because there is no 0x200C in the font
append = true, -- this is done late
overload = false, -- we don't want to overload the previous definition
lookups = {
{
type = "ligature",
data = lookups,
},
},
data = {
rules = revert,
}
}
registerotffeature {
name = 'blockligatures',
description = 'block certain ligatures',
}
local splitter = lpeg.splitat(":")
local function blockligatures(str)
local t = settings_to_array(str)
for i=1,#t do
local ti = t[i]
local before, current, after = lpegmatch(splitter,ti)
if current and after then -- before is returned when no match
-- experimental joke
if before then
before = utfsplit(before)
for i=1,#before do
before[i] = { before[i] }
end
end
if current then
current = utfsplit(current)
end
if after then
after = utfsplit(after)
for i=1,#after do
after[i] = { after[i] }
end
end
else
before = nil
current = utfsplit(ti)
after = nil
end
if #current > 1 then
local one = current[1]
local two = current[2]
lookups[one] = { one, zwjchar }
local one = { one }
local two = { two }
local new = #protect + 1
protect[new] = {
before = before,
current = { one, two },
after = after,
lookups = { 1 }, -- not shared !
}
revert[new] = {
-- before = before,
current = { one, zwj },
-- after = { two, unpack(after) },
after = { two },
lookups = { 1 }, -- not shared !
}
end
end
end
-- blockligatures("\0\0")
otf.helpers.blockligatures = blockligatures
-- blockligatures("fi,ff")
-- blockligatures("fl")
-- blockligatures("u:fl:age")
if context then
interfaces.implement {
name = "blockligatures",
arguments = "string",
actions = blockligatures,
}
end
|
