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-rw-r--r--tex/context/base/attr-neg.lua71
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diff --git a/tex/context/base/attr-neg.lua b/tex/context/base/attr-neg.lua
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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
+
+--- negative / positive
+
+attributes.negatives = attributes.negatives or { }
+local negatives = attributes.negatives
+negatives.data = negatives.data or { }
+negatives.attribute = attributes.private("negative")
+
+negatives.registered = {
+ positive = 1,
+ 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 })
+
+function negatives.register(stamp)
+ return registered[stamp] or registered.positive
+end
+
+attributes.negatives.handler = nodes.install_attribute_handler {
+ name = "negative",
+ namespace = negatives,
+ initializer = states.initialize,
+ finalizer = states.finalize,
+ processor = states.process,
+}
+
+function negatives.enable()
+ tasks.enableaction("shipouts","attributes.negatives.handler")
+end