if not modules then modules = { } end modules ['typo-dha'] = {
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"
}
-- Some analysis by Idris:
--
-- 1. Assuming the reading- vs word-order distinction (bidi-char types) is governing;
-- 2. Assuming that 'ARAB' represents an actual arabic string in raw input order, not word-order;
-- 3. Assuming that 'BARA' represent the correct RL word order;
--
-- Then we have, with input: LATIN ARAB
--
-- \textdirection 1 LATIN ARAB => LATIN BARA
-- \textdirection 1 LATIN ARAB => LATIN BARA
-- \textdirection 1 LRO LATIN ARAB => LATIN ARAB
-- \textdirection 1 LRO LATIN ARAB => LATIN ARAB
-- \textdirection 1 RLO LATIN ARAB => NITAL ARAB
-- \textdirection 1 RLO LATIN ARAB => NITAL ARAB
-- elseif d == "es" then -- European Number Separator
-- elseif d == "et" then -- European Number Terminator
-- elseif d == "cs" then -- Common Number Separator
-- elseif d == "nsm" then -- Non-Spacing Mark
-- elseif d == "bn" then -- Boundary Neutral
-- elseif d == "b" then -- Paragraph Separator
-- elseif d == "s" then -- Segment Separator
-- elseif d == "ws" then -- Whitespace
-- elseif d == "on" then -- Other Neutrals
-- todo : use new dir functions
-- todo : make faster
-- todo : move dir info into nodes
-- todo : swappable tables and floats i.e. start-end overloads (probably loop in builders)
-- I removed the original tracing code and now use the colorful one. If I ever want to change
-- something I will just inject prints for tracing.
local nodes, node = nodes, node
local trace_directions = false trackers.register("typesetters.directions", function(v) trace_directions = v end)
local report_directions = logs.reporter("typesetting","text directions")
local nuts = nodes.nuts
local getnext = nuts.getnext
local getprev = nuts.getprev
local getchar = nuts.getchar
local getid = nuts.getid
local getsubtype = nuts.getsubtype
local getlist = nuts.getlist
local getattr = nuts.getattr
local getprop = nuts.getprop
local getdirection = nuts.getdirection
local isglyph = nuts.isglyph -- or ischar
local setprop = nuts.setprop
local setstate = nuts.setstate
local setchar = nuts.setchar
local insertnodebefore = nuts.insertbefore
local insertnodeafter = nuts.insertafter
local remove_node = nuts.remove
local endofmath = nuts.endofmath
local startofpar = nuts.startofpar
local nodepool = nuts.pool
local nodecodes = nodes.nodecodes
local gluecodes = nodes.gluecodes
local glyph_code = nodecodes.glyph
local math_code = nodecodes.math
local kern_code = nodecodes.kern
local glue_code = nodecodes.glue
local dir_code = nodecodes.dir
local par_code = nodecodes.par
local dirvalues = nodes.dirvalues
local lefttoright_code = dirvalues.lefttoright
local righttoleft_code = dirvalues.righttoleft
local parfillskip_code = gluecodes.parfillskip
local new_direction = nodepool.direction
local insert = table.insert
local fonthashes = fonts.hashes
local fontchar = fonthashes.characters
local chardirections = characters.directions
local charmirrors = characters.mirrors
local charclasses = characters.textclasses
local directions = typesetters.directions
local setcolor = directions.setcolor
local getglobal = directions.getglobal
local a_directions = attributes.private('directions')
local strip = false
local s_isol = fonts.analyzers.states.isol
local function stopdir(finish) -- we could use finish directly
local n = new_direction(finish == righttoleft_code and righttoleft_code or lefttoright_code,true)
setprop(n,"direction",true)
return n
end
local function startdir(finish) -- we could use finish directly
local n = new_direction(finish == righttoleft_code and righttoleft_code or lefttoright_code)
setprop(n,"direction",true)
return n
end
local function nextisright(current)
current = getnext(current)
local character, id = isglyph(current)
if character then
local direction = chardirections[character]
return direction == "r" or direction == "al" or direction == "an"
end
end
local function previsright(current)
current = getprev(current)
local character, id = isglyph(current)
if character then
local direction = chardirections[character]
return direction == "r" or direction == "al" or direction == "an"
end
end
local function process(start)
local head = start
local current = head
local autodir = 0
local embedded = 0
local override = 0
local pardir = 0
local textdir = 0
local done = false
local stack = { }
local top = 0
local obsolete = { }
local rlo = false
local lro = false
local prevattr = false
local fences = { }
while current do
-- no isglyph here as we test for skips first
local id = getid(current)
local next = getnext(current)
if id == math_code then
current = getnext(endofmath(next))
elseif getprop(current,"direction") then
-- this handles unhbox etc
current = next
else
local attr = getattr(current,a_directions)
if attr and attr > 0 then
if attr ~= prevattr then
if not getglobal(a) then
lro = false
rlo = false
end
prevattr = attr
end
end
if id == glyph_code then
if attr and attr > 0 then
local character, font = isglyph(current)
if character == 0 then
-- skip signals
setprop(current,"direction",true)
else
local direction = chardirections[character]
local reversed = false
if rlo or override > 0 then
if direction == "l" then
direction = "r"
reversed = true
end
elseif lro or override < 0 then
if direction == "r" or direction == "al" then
setstate(current,s_isol) -- hm
direction = "l"
reversed = true
end
end
if direction == "on" then
local mirror = charmirrors[character]
if mirror and fontchar[font][mirror] then
local class = charclasses[character]
if class == "open" then
if nextisright(current) then
setchar(current,mirror)
setprop(current,"direction","r")
elseif autodir < 0 then
setchar(current,mirror)
setprop(current,"direction","r")
else
mirror = false
setprop(current,"direction","l")
end
local fencedir = autodir == 0 and textdir or autodir
fences[#fences+1] = fencedir
elseif class == "close" and #fences > 0 then
local fencedir = fences[#fences]
fences[#fences] = nil
if fencedir < 0 then
setchar(current,mirror)
setprop(current,"direction","r")
else
setprop(current,"direction","l")
mirror = false
end
elseif autodir < 0 then
setchar(current,mirror)
setprop(current,"direction","r")
else
setprop(current,"direction","l")
mirror = false
end
else
setprop(current,"direction",true)
end
if trace_directions then
setcolor(current,direction,false,mirror)
end
elseif direction == "l" then
if trace_directions then
setcolor(current,"l",reversed)
end
setprop(current,"direction","l")
elseif direction == "r" then
if trace_directions then
setcolor(current,"r",reversed)
end
setprop(current,"direction","r")
elseif direction == "en" then -- european number
if trace_directions then
setcolor(current,"l")
end
setprop(current,"direction","l")
elseif direction == "al" then -- arabic letter
if trace_directions then
setcolor(current,"r")
end
setprop(current,"direction","r")
elseif direction == "an" then -- arabic number
-- needs a better scanner as it can be a float
if trace_directions then
setcolor(current,"l") -- was r
end
setprop(current,"direction","n") -- was r
elseif direction == "lro" then -- Left-to-Right Override -> right becomes left
top = top + 1
stack[top] = { override, embedded }
override = -1
obsolete[#obsolete+1] = current
elseif direction == "rlo" then -- Right-to-Left Override -> left becomes right
top = top + 1
stack[top] = { override, embedded }
override = 1
obsolete[#obsolete+1] = current
elseif direction == "lre" then -- Left-to-Right Embedding -> lefttoright_code
top = top + 1
stack[top] = { override, embedded }
embedded = 1
obsolete[#obsolete+1] = current
elseif direction == "rle" then -- Right-to-Left Embedding -> righttoleft_code
top = top + 1
stack[top] = { override, embedded }
embedded = -1
obsolete[#obsolete+1] = current
elseif direction == "pdf" then -- Pop Directional Format
if top > 0 then
local s = stack[top]
override = s[1]
embedded = s[2]
top = top - 1
else
override = 0
embedded = 0
end
obsolete[#obsolete+1] = current
elseif trace_directions then
setcolor(current)
setprop(current,"direction",true)
else
setprop(current,"direction",true)
end
end
else
setprop(current,"direction",true)
end
elseif id == glue_code then
if getsubtype(current) == parfillskip_code then
setprop(current,"direction",'!')
else
setprop(current,"direction",'g')
end
elseif id == kern_code then
setprop(current,"direction",'k')
elseif id == dir_code then
local direction, pop = getdirection(current)
if direction == righttoleft_code then
if not pop then
autodir = -1
elseif embedded and embedded~= 0 then
autodir = embedded
else
autodir = 0
end
elseif direction == lefttoright_code then
if not pop then
autodir = 1
elseif embedded and embedded~= 0 then
autodir = embedded
else
autodir = 0
end
end
textdir = autodir
setprop(current,"direction",true)
elseif id == par_code and startofpar(current) then
local direction = getdirection(current)
if direction == righttoleft_code then
autodir = -1
elseif direction == lefttoright_code then
autodir = 1
end
pardir = autodir
textdir = pardir
setprop(current,"direction",true)
else
setprop(current,"direction",true)
end
current = next
end
end
-- todo: track if really needed
-- todo: maybe we need to set the property (as it can be a copied list)
if done and strip then
local n = #obsolete
if n > 0 then
for i=1,n do
remove_node(head,obsolete[i],true)
end
if trace_directions then
report_directions("%s character nodes removed",n)
end
end
end
local state = false
local last = false
local collapse = true
current = head
-- todo: textdir
-- todo: inject before parfillskip
while current do
local id = getid(current)
if id == math_code then
-- todo: this might be tricky nesting
current = getnext(endofmath(getnext(current)))
else
local cp = getprop(current,"direction")
if cp == "n" then
local swap = state == "r"
if swap then
head = insertnodebefore(head,current,startdir(lefttoright_code))
end
setprop(current,"direction",true)
while true do
local n = getnext(current)
if n and getprop(n,"direction") == "n" then
current = n
setprop(current,"direction",true)
else
break
end
end
if swap then
head, current = insertnodeafter(head,current,stopdir(lefttoright_code))
end
elseif cp == "l" then
if state ~= "l" then
if state == "r" then
head = insertnodebefore(head,last or current,stopdir(righttoleft_code))
end
head = insertnodebefore(head,current,startdir(lefttoright_code))
state = "l"
done = true
end
last = false
elseif cp == "r" then
if state ~= "r" then
if state == "l" then
head = insertnodebefore(head,last or current,stopdir(lefttoright_code))
end
head = insertnodebefore(head,current,startdir(righttoleft_code))
state = "r"
done = true
end
last = false
elseif collapse then
if cp == "k" or cp == "g" then
last = last or current
else
last = false
end
else
if state == "r" then
head = insertnodebefore(head,current,stopdir(righttoleft_code))
elseif state == "l" then
head = insertnodebefore(head,current,stopdir(lefttoright_code))
end
state = false
last = false
end
setprop(current,"direction",true)
end
local next = getnext(current)
if next then
current = next
else
local sd = (state == "r" and stopdir(righttoleft_code)) or (state == "l" and stopdir(lefttoright_code))
if sd then
if id == glue_code and getsubtype(current) == parfillskip_code then
head = insertnodebefore(head,current,sd)
else
head = insertnodeafter(head,current,sd)
end
end
break
end
end
return head
end
directions.installhandler(interfaces.variables.default,process)