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if not modules then modules = { } end modules ['typo-dir'] = {
version = 1.001,
comment = "companion to typo-dir.mkiv",
author = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
copyright = "PRAGMA ADE / ConTeXt Development Team",
license = "see context related readme files"
}
-- When we started with this, there were some issues in luatex so we needed to take care of
-- intereferences. Some has been improved but we stil might end up with each node having a
-- dir property. Now, the biggest problem is that there is an official bidi algorithm but
-- some searching on the web shows that there are many confusing aspects and therefore
-- proposals circulate about (sometimes imcompatible ?) improvements. In the end it all boils
-- down to the lack of willingness to tag an input source. Of course tagging of each number
-- and fenced strip is somewhat over the top, but now it has to be captured in logic. Texies
-- normally have no problem with tagging but we need to handle any input. So, what we have
-- done here (over the years) is starting from what we expect to see happen, especially with
-- respect to punctation, numbers and fences. Eventually alternative algorithms will be provides
-- so that users can choose (the reason why suggestion sfor improvements circulate on the web
-- is that it is non trivial to predict the expected behaviour so one hopes that the ditor
-- and the rest of the machinery match somehow. Anyway, the fun of tex is that it has no hard
-- coded behavior. And ... we also want to have more debugging and extras and ... so we want
-- a flexible approach. In the end we will have:
--
-- = full tagging (mechanism turned off)
-- = half tagging (the current implementation)
-- = unicode version x interpretation (several depending on the evolution)
local next, type = next, type
local format, insert, sub, find, match = string.format, table.insert, string.sub, string.find, string.match
local utfchar = utf.char
local formatters = string.formatters
local nodes, node = nodes, node
local trace_textdirections = false trackers.register("typesetters.directions.text", function(v) trace_textdirections = v end)
local trace_mathdirections = false trackers.register("typesetters.directions.math", function(v) trace_mathdirections = v end)
local trace_directions = false trackers.register("typesetters.directions", function(v) trace_textdirections = v trace_mathdirections = v end)
local report_textdirections = logs.reporter("typesetting","text directions")
local report_mathdirections = logs.reporter("typesetting","math directions")
local traverse_id = node.traverse_id
local insert_node_before = node.insert_before
local insert_node_after = node.insert_after
local remove_node = nodes.remove
local end_of_math = nodes.end_of_math
local texsetattribute = tex.setattribute
local texsetcount = tex.setcount
local unsetvalue = attributes.unsetvalue
local nodecodes = nodes.nodecodes
local whatcodes = nodes.whatcodes
local mathcodes = nodes.mathcodes
local tasks = nodes.tasks
local glyph_code = nodecodes.glyph
local whatsit_code = nodecodes.whatsit
local math_code = nodecodes.math
local penalty_code = nodecodes.penalty
local kern_code = nodecodes.kern
local glue_code = nodecodes.glue
local hlist_code = nodecodes.hlist
local vlist_code = nodecodes.vlist
local localpar_code = whatcodes.localpar
local dir_code = whatcodes.dir
local nodepool = nodes.pool
local new_textdir = nodepool.textdir
local fonthashes = fonts.hashes
local fontdata = fonthashes.identifiers
local fontchar = fonthashes.characters
local chardirections = characters.directions
local charmirrors = characters.mirrors
local charclasses = characters.textclasses
local directions = typesetters.directions or { }
typesetters.directions = directions
local a_state = attributes.private('state')
local a_directions = attributes.private('directions')
local a_mathbidi = attributes.private('mathbidi')
local strip = false
local s_isol = fonts.analyzers.states.isol
local variables = interfaces.variables
local v_global = variables["global"]
local v_local = variables["local"]
local v_on = variables.on
local v_yes = variables.yes
local m_enabled = 2^6 -- 64
local m_global = 2^7
local m_fences = 2^8
local handlers = { }
local methods = { }
local lastmethod = 0
local function installhandler(name,handler)
local method = methods[name]
if not method then
lastmethod = lastmethod + 1
method = lastmethod
methods[name] = method
end
handlers[method] = handler
return method
end
directions.handlers = handlers
directions.installhandler = installhandler
local function tomode(specification)
local scope = specification.scope
local mode
if scope == v_global or scope == v_on then
mode = m_enabled + m_global
elseif scope == v_local then
mode = m_enabled
else
return 0
end
local method = methods[specification.method]
if method then
mode = mode + method
else
return 0
end
if specification.fences == v_yes then
mode = mode + m_fences
end
return mode
end
local function getglobal(a)
return a and a > 0 and hasbit(a,m_global)
end
local function getfences(a)
return a and a > 0 and hasbit(a,m_fences)
end
local function getmethod(a)
return a and a > 0 and a % m_enabled or 0
end
directions.tomode = tomode
directions.getglobal = getglobal
directions.getfences = getfences
directions.getmethod = getmethod
directions.installhandler = installhandler
function commands.getbidimode(specification)
context(tomode(specification)) -- hash at tex end
end
local enabled = false
local starttiming = statistics.starttiming
local stoptiming = statistics.stoptiming
function directions.process(namespace,attribute,head) -- for the moment nodes and not nuts
if not head.next then
return head, false
end
local attr = head[a_directions]
if not attr or attr == 0 then
return head, false
end
local method = getmethod(attr)
local handler = handlers[method]
if not handler then
return head, false
end
starttiming(directions)
local head, done = handler(namespace,attribute,head)
stoptiming(directions)
return head, done
end
-- function directions.enable()
-- tasks.enableaction("processors","directions.handler")
-- end
function directions.set(n) -- todo: names and numbers
if not enabled then
if trace_textdirections then
report_textdirections("enabling directions handler")
end
tasks.enableaction("processors","typesetters.directions.handler")
enabled = true
end
if not n or n == 0 then
n = unsetvalue
-- maybe tracing
end
texsetattribute(a_directions,n)
end
commands.setdirection = directions.set
directions.handler = nodes.installattributehandler {
name = "directions",
namespace = directions,
processor = directions.process,
}
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