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if not modules then modules = { } end modules ['attr-neg'] = {
version = 1.001,
comment = "companion to attr-neg.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
-- this module is being reconstructed and code will move to other places
-- we can also do the nsnone via a metatable and then also se index 0
local format = string.format
local attributes, nodes = attributes, nodes
local states = attributes.states
local tasks = nodes.tasks
local nodeinjections = backends.nodeinjections
local settexattribute = tex.setattribute
local variables = interfaces.variables
--- negative / positive
attributes.negatives = attributes.negatives or { }
local negatives = attributes.negatives
local a_negative = attributes.private("negative")
negatives.data = negatives.data or { }
negatives.attribute = a_negative
negatives.registered = {
[variables.positive] = 1,
[variables.negative] = 2,
}
local data, registered = negatives.data, negatives.registered
local function extender(negatives,key)
if key == "none" then
local d = data[1]
negatives.none = d
return d
end
end
local function reviver(data,n)
if n == 1 then
local d = nodeinjections.positive() -- called once
data[1] = d
return d
elseif n == 2 then
local d = nodeinjections.negative() -- called once
data[2] = d
return d
end
end
setmetatable(negatives, { __index = extender })
setmetatable(negatives.data, { __index = reviver })
negatives.handler = nodes.installattributehandler {
name = "negative",
namespace = negatives,
initializer = states.initialize,
finalizer = states.finalize,
processor = states.process,
}
local function register(stamp)
return registered[stamp] or registered.positive
end
local function enable()
tasks.enableaction("shipouts","attributes.negatives.handler")
end
negatives.register = register
negatives.enable = enable
-- interface
local enabled = false
function commands.triggernegative(stamp)
if not enabled then
enable()
enabled = true
end
settexattribute(a_negative,register(stamp))
end
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