1 files changed, 21 insertions, 4 deletions
diff --git a/Master/texmf-dist/tex/generic/babel/babel-bidi-basic.lua b/Master/texmf-dist/tex/generic/babel/babel-bidi-basic.lua
index 8fe47ecb80f..be342c12fe5 100644
--- a/Master/texmf-dist/tex/generic/babel/babel-bidi-basic.lua
+++ b/Master/texmf-dist/tex/generic/babel/babel-bidi-basic.lua
@@ -91,8 +91,11 @@ local function insert_numeric(head, state)
   return head, new_state
 end
 
--- \hbox with an explicit dir can lead to wrong results
--- <R \hbox dir TLT{<R>}> and <L \hbox dir TRT{<L>}>
+-- TODO - \hbox with an explicit dir can lead to wrong results
+-- <R \hbox dir TLT{<R>}> and <L \hbox dir TRT{<L>}>. A small attempt
+-- was s made to improve the situation, but the problem is the 3-dir
+-- model in babel/Unicode and the 2-dir model in LuaTeX don't fit
+-- well.
 
 function Babel.bidi(head, ispar, hdir)
   local d   -- d is used mainly for computations in a loop
@@ -101,6 +104,7 @@ function Babel.bidi(head, ispar, hdir)
 
   local nodes = {}
   local outer_first = nil
+  local inmath = false
 
   local glue_d = nil
   local glue_i = nil
@@ -119,9 +123,14 @@ function Babel.bidi(head, ispar, hdir)
                  (temp == 2 and 'al')
   elseif ispar then            -- Or error? Shouldn't happen
     save_outer = ('TRT' == tex.pardir) and 'r' or 'l'
-  else
+  else                         -- Or error? Shouldn't happen
     save_outer = ('TRT' == hdir) and 'r' or 'l'
   end
+    -- when the callback is called, we are just _after_ the box,
+    -- and the textdir is that of the surrounding text
+  -- if not ispar and hdir ~= tex.textdir then
+  --   save_outer = ('TRT' == hdir) and 'r' or 'l'
+  -- end
   local outer = save_outer
   local last = outer
   -- 'al' is only taken into account in the first, current loop
@@ -160,6 +169,7 @@ function Babel.bidi(head, ispar, hdir)
         end
       end
       d = d or 'l'
+      if inmath then d = ('TRT' == tex.mathdir) and 'r' or 'l' end
       d_font = d_font or d
 
       d_font = (d_font == 'l' and 0) or
@@ -208,6 +218,9 @@ function Babel.bidi(head, ispar, hdir)
       glue_i = item
       d = nil
 
+    elseif item.id == node.id'math' then
+      inmath = (item.subtype == 0)
+
     else
       d = nil
     end
@@ -371,7 +384,11 @@ function Babel.bidi(head, ispar, hdir)
       end
     else
       if d == 'an' or d == 'l' then
-        state.sim = state.sim or item
+        if nodes[q][3] then -- nil except after an explicit dir
+          state.sim = item  -- so we move sim 'inside' the group
+        else
+          state.sim = state.sim or item
+        end
         state.eim = item
       elseif d == 'r' and state.sim then
         head, state = insert_implicit(head, state, outer)