{multline} support (without labels on the left)

luamml-amsmath.lua

@@ -4,6 +4,7 @@ local save_result = require'luamml-tex'.save_result
 local store_column = require'luamml-table'.store_column
 local store_tag = require'luamml-table'.store_tag
 local get_table = require'luamml-table'.get_table
+local set_row_attribute = require'luamml-table'.set_row_attribute
 local to_text = require'luamml-lr'
 
 local properties = node.get_properties_table()
@@ -36,6 +37,12 @@ lua.get_functions_table()[funcid] = function()
   store_column(startmath)
 end
 
+local funcid = luatexbase.new_luafunction'__luamml_amsmath_set_row_columnalign:n'
+token.set_lua('__luamml_amsmath_set_row_columnalign:n', funcid, 'protected')
+lua.get_functions_table()[funcid] = function()
+  set_row_attribute('columnalign', token.scan_argument())
+end
+
 do
   local saved
   funcid = luatexbase.new_luafunction'__luamml_amsmath_save_inner_table:n'
@@ -81,6 +88,7 @@ lua.get_functions_table()[funcid] = function()
   mml_table.displaystyle = true
   local columns = node.count(node.id'align_record', tex.lists.align_head)//2
   mml_table.columnalign = kind == 'align' and string.rep('right left', columns, ' ') or nil
+  mml_table.width = kind == 'multline' and '100%' or nil
   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 '.8em'

luamml-patches-amsmath.sty

@@ -271,6 +271,83 @@
   \ignorespacesafterend
 }
 
+% For a more interesting one, let's consider multline:
+\cs_new_eq:NN \__luamml_amsmath_original_multline:n \multline@
+\cs_set:Npn \multline@ #1 {
+  \__luamml_amsmath_original_multline:n {
+    \ifmeasuring@ \else
+      \__luamml_amsmath_set_row_columnalign:n {left}
+    \fi
+    #1
+    \ifmeasuring@ \else
+      \__luamml_amsmath_set_row_columnalign:n {right}
+    \fi
+  }
+}
+
+\cs_new_eq:NN \__luamml_amsmath_original_mmeasure:n \mmeasure@
+\cs_set:Npn \mmeasure@ #1 {
+  \exp_last_unbraced:Nno
+    \use_ii_i:nn
+    { \luamml_flag_ignore: }
+    { \__luamml_amsmath_original_mmeasure:n {#1} }
+}
+
+% Luckily, {multline} uses \endmultline@math in exactly
+% the spot where we have to set the flag.
+% Less luckily, \endmultline@math sometimes get overwritten for the last line.
+% But that isn't a problem since we want special behavior there anyway.
+\cs_set:Npn \endmultline@math {
+  \luamml_flag_save:Nn \displaystyle {mtd}
+  $
+  \__luamml_amsmath_add_last_to_row:
+}
+
+\cs_set:Npn \rendmultline@ {
+    \iftag@
+      \luamml_flag_save:Nn \displaystyle {mtd}
+      $
+      \__luamml_amsmath_add_last_to_row:
+      \let \endmultline@math \relax
+      \ifshifttag@
+        \hskip \multlinegap
+        \llap {
+          \vtop {
+            \raise@tag
+            \normalbaselines
+            \setbox \@ne \null
+            \dp \@ne \lineht@
+            \box \@ne
+            \hbox {
+              \strut@
+              \make@display@tag
+            }
+          }
+        }
+      \else
+        \hskip \multlinetaggap
+        \make@display@tag
+      \fi
+      \__luamml_amsmath_set_tag:
+    \else
+      \hskip \multlinegap
+    \fi
+    \hfilneg
+    \math@cr
+    \__luamml_amsmath_finalize_table:n {multline}
+  \egroup
+  $$
+}
+
+\cs_set:Npn \lendmultline@ {
+    \hfilneg
+    \hskip\multlinegap
+    \math@cr
+    \__luamml_amsmath_finalize_table:n {multline}
+  \egroup
+  $$
+}
+
 \cs_set:Npn \bBigg@ #1 #2 {
   {
     \ensuremath {

luamml-table.lua

@@ -4,8 +4,23 @@ local save_result = require'luamml-tex'.save_result
 
 local properties = node.get_properties_table()
 
+local glue_id = node.id'glue'
+local tabskip_sub = 12
+assert(node.subtypes'glue'[tabskip_sub] == 'tabskip')
+
 local function store_get_row()
-  local row_temp = tex.nest[tex.nest.ptr-1].head
+  local row_temp
+  for i=tex.nest.ptr-1, 0, -1 do
+    local head = tex.nest[i].head
+    local glue = head.next
+    if glue and glue.id == glue_id and glue.subtype == tabskip_sub then
+      row_temp = head
+      break
+    end
+  end
+  if not row_temp then
+    error[[luamml_table's store function called outside of table]]
+  end
   local props = properties[row_temp]
   if not props then
     props = {}
@@ -48,6 +63,11 @@ local function store_tag(xml)
   last_tag = nil
 end
 
+local function set_row_attribute(name, value)
+  local mml_row = store_get_row()
+  mml_row[name] = value
+end
+
 luatexbase.add_to_callback('hpack_filter', function(_, group)
   if group ~= 'fin_row' then return true end
 
@@ -85,5 +105,6 @@ return {
   store_column = store_column,
   store_column_xml = store_column_xml,
   store_tag = store_tag,
+  set_row_attribute = set_row_attribute,
   get_table = get_table,
 }