From fcfe981c9e34bb88f5ca7ceb7e41b7b2b68dcf03 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcel=20Fabian=20Kr=C3=BCger?= <tex@2krueger.de>
Date: Fri, 18 Jun 2021 23:03:39 +0200
Subject: [PATCH] Support aligned

---
 luamml-amsmath.lua         | 53 ++++++++++++++++++++++++++++++-
 luamml-patches-amsmath.sty | 64 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 113 insertions(+), 4 deletions(-)

diff --git a/luamml-amsmath.lua b/luamml-amsmath.lua
index eacb91f..40da8c4 100644
--- a/luamml-amsmath.lua
+++ b/luamml-amsmath.lua
@@ -8,6 +8,23 @@ local to_text = require'luamml-lr'
 
 local properties = node.get_properties_table()
 
+local math_t = node.id'math'
+
+local funcid = luatexbase.new_luafunction'__luamml_amsmath_add_last_to_row:'
+token.set_lua('__luamml_amsmath_add_last_to_row:', funcid, 'protected')
+lua.get_functions_table()[funcid] = function()
+  -- TODO: Error handling etc
+  -- local box = token.scan_int()
+  local nest = tex.nest.top
+  local head, startmath = nest.head, nest.tail
+  repeat
+    startmath = startmath.prev
+  until startmath == head or (startmath.id == math_t and startmath.subtype == 0)
+  if startmath == head then return end
+  assert(startmath.id == node.id"math")
+  store_column(startmath, true)
+end
+
 local funcid = luatexbase.new_luafunction'__luamml_amsmath_add_box_to_row:'
 token.set_lua('__luamml_amsmath_add_box_to_row:', funcid, 'protected')
 lua.get_functions_table()[funcid] = function()
@@ -15,10 +32,44 @@ lua.get_functions_table()[funcid] = function()
   -- local box = token.scan_int()
   local boxnum = 0
   local startmath = tex.box[boxnum].list
-  assert(startmath.id == node.id"math")
+  assert(startmath.id == math_t)
   store_column(startmath, true)
 end
 
+do
+  local saved
+  funcid = luatexbase.new_luafunction'__luamml_amsmath_save_inner_table:'
+  token.set_lua('__luamml_amsmath_save_inner_table:', funcid)
+  lua.get_functions_table()[funcid] = function()
+    -- TODO: Error handling etc
+    local mml_table = get_table()
+    if not mml_table then return end
+    mml_table.displaystyle = true
+    local columns = node.count(node.id'align_record', tex.lists.align_head)//2
+    mml_table.columnalign = string.rep('right left', columns, ' ')
+    local spacing = {}
+    for n in node.traverse_id(node.id'glue', tex.lists.align_head) do
+      spacing[#spacing+1] = n.width == 0 and '0' or string.format('%.3f', n.width/65781.76)
+    end
+    mml_table.columnspacing = table.concat(spacing, ' ', 2, #spacing-2)
+    saved = mml_table
+  end
+
+  funcid = luatexbase.new_luafunction'__luamml_amsmath_finalize_inner_table:'
+  token.set_lua('__luamml_amsmath_finalize_inner_table:', funcid)
+  lua.get_functions_table()[funcid] = function()
+    -- TODO: Error handling etc
+    local vcenter = tex.nest.top.tail.nucleus
+    local props = properties[vcenter]
+    if not props then
+      props = {}
+      properties[vcenter] = props
+    end
+    props.mathml_table = assert(saved)
+    saved = nil
+  end
+end
+
 funcid = luatexbase.new_luafunction'__luamml_amsmath_finalize_table:'
 token.set_lua('__luamml_amsmath_finalize_table:', funcid)
 lua.get_functions_table()[funcid] = function()
diff --git a/luamml-patches-amsmath.sty b/luamml-patches-amsmath.sty
index b37bf4d..c5d2423 100644
--- a/luamml-patches-amsmath.sty
+++ b/luamml-patches-amsmath.sty
@@ -3,6 +3,65 @@
 
 \lua_now:n { require'luamml-amsmath' }
 
+\cs_set:Npn \start@aligned #1#2 {
+  \RIfM@
+  \else
+    \nonmatherr@ { \begin { \@currenvir } }
+  \fi
+  \savecolumn@ % Assumption: called inside a group
+  \alignedspace@left
+  \ams@start@box {#1} \bgroup
+    \maxfields@ #2 \relax
+    \ifnum \maxfields@ > \m@ne
+      \multiply \maxfields@ \tw@
+      \let \math@cr@@@ \math@cr@@@alignedat
+      \alignsep@ \z@skip
+    \else
+      \let \math@cr@@@ \math@cr@@@aligned
+      \alignsep@ \minalignsep
+    \fi
+    \Let@ \chardef \dspbrk@context \@ne
+    \default@tag
+    \spread@equation % no-op if already called
+    \global \column@ \z@
+    \ialign \bgroup
+      & \column@plus
+        \hfil
+        \strut@
+        $
+          \m@th
+          \displaystyle
+          {##}
+          \luamml_flag_save:N \displaystyle
+        $
+        \__luamml_amsmath_add_last_to_row:
+        \tabskip \z@skip
+      & \column@plus
+        $
+          \m@th
+          \displaystyle
+          {
+            {}
+            ##
+          }
+          \luamml_flag_save:N \displaystyle
+        $
+        \__luamml_amsmath_add_last_to_row:
+        \hfil
+        \tabskip\alignsep@
+      \crcr
+      \ams@return@opt@arg
+}
+
+\cs_set:Npn \endaligned {
+      \crcr
+      \__luamml_amsmath_save_inner_table:
+    \egroup
+    \restorecolumn@
+  \egroup
+  \__luamml_amsmath_finalize_inner_table:
+}
+
 \cs_set:Npn \align@preamble {
   &
     \hfil
@@ -11,9 +70,8 @@
       \@lign
       $
         \m@th
-        \displaystyle {
-          ##
-        }
+        \displaystyle
+        {##}
         \ifmeasuring@
           \luamml_flag_ignore:
         \else