Don't require unicode-math

mlist_to_mml.lua

@@ -14,6 +14,16 @@ local noad_sub = node.subtypes'noad'
 local radical_sub = node.subtypes'radical'
 local fence_sub = node.subtypes'fence'
 
+local remap_lookup = setmetatable({}, {__index = function(t, k)
+  local ch = utf8.char(k & 0x1FFFFF)
+  t[k] = ch
+  return ch
+end})
+local digit_map = {["0"] = true, ["1"] = true,
+     ["2"] = true, ["3"] = true, ["4"] = true,
+     ["5"] = true, ["6"] = true, ["7"] = true,
+     ["8"] = true, ["9"] = true,}
+
 local nodes_to_table
 
 local function sub_style(s) return s//4*2+5 end
@@ -25,7 +35,8 @@ local function delim_to_table(delim)
   local props = properties[delim] props = props and props.mathml_table
   if props then return props end
   local fam = delim.small_fam
-  return {[0] = 'mo', utf8.char(delim.small_char), ['tex:family'] = fam ~= 0 and fam or nil, stretchy = not stretchy[delim.small_char] or nil }
+  local char = remap_lookup[fam << 21 | delim.small_char]
+  return {[0] = 'mo', char, ['tex:family'] = fam ~= 0 and fam or nil, stretchy = not stretchy[char] or nil }
 end
 
 -- Like kernel_to_table but always a math_char_t. Also creating a mo and potentially remapping to handle combining chars
@@ -36,9 +47,9 @@ local function acc_to_table(acc, cur_style, stretch)
   if acc.id ~= math_char_t then
     error'confusion'
   end
-  local char = utf8.char(acc.char)
-  char = remap_comb[char] or char
   local fam = acc.fam
+  local char = remap_lookup[fam << 21 | acc.char]
+  char = remap_comb[char] or char
   if stretch ~= not stretchy[char] then -- Handle nil gracefully in stretchy
     stretch = nil
   end
@@ -51,10 +62,14 @@ local function kernel_to_table(kernel, cur_style)
   if props then return props end
   local id = kernel.id
   if id == math_char_t then
-    local char = kernel.char
-    local elem = char >= 0x30 and char < 0x39 and 'mn' or 'mi'
     local fam = kernel.fam
-    return {[0] = elem, utf8.char(char), ['tex:family'] = fam ~= 0 and fam or nil, mathvariant = char < 0x10000 and 'normal' or nil }
+    local char = remap_lookup[fam << 21 | kernel.char]
+    local elem = digit_map[char] and 'mn' or 'mi'
+    return {[0] = elem,
+      char,
+      ['tex:family'] = fam ~= 0 and fam or nil,
+      mathvariant = #char == 1 and utf8.codepoint(char) < 0x10000 and 'normal' or nil
+    }
   elseif id == sub_box_t then
     return {[0] = 'mi', {[0] = 'mglyph', ['tex:box'] = kernel.list}}
   elseif id == sub_mlist_t then
@@ -269,7 +284,14 @@ function nodes_to_table(head, cur_style)
   return result
 end
 
-return function(head, style)
+local function register_remap(family, mapping)
+  family = family << 21
+  for from, to in next, mapping do
+    remap_lookup[family | from] = utf8.char(to)
+  end
+end
+
+local function to_mml(head, style)
   local result = nodes_to_table(head, style or 0)
   result[0] = 'math'
   result.xmlns = 'http://www.w3.org/1998/Math/MathML'
@@ -279,3 +301,8 @@ return function(head, style)
   end
   return result
 end
+
+return {
+  register_family = register_remap,
+  process = to_mml,
+}

test_tex.lua

@@ -1,14 +1,30 @@
 local inspect = require'inspect'
 local function show(t) return print(inspect(t)) end
 
-local mlist_to_table = require'mlist_to_mml'
+local mlist_to_mml = require'mlist_to_mml'
+local process_mlist = mlist_to_mml.process
+local register_family = mlist_to_mml.register_family
+
+local mappings = require'remap'
 local write_xml = require'write_xml'
 
+local funcid = luatexbase.new_luafunction'RegisterFamilyMapping'
+token.set_lua('RegisterFamilyMapping', funcid, 'protected')
+lua.get_functions_table()[funcid] = function()
+  local fam = token.scan_int()
+  local mapping = token.scan_string()
+  if mappings[mapping] then
+    register_family(fam, mappings[mapping])
+  else
+    tex.error(string.format('Unknown font mapping %q', mapping))
+  end
+end
+
 luatexbase.add_to_callback('pre_mlist_to_hlist_filter', function(mlist, style)
-  print'\n\n'
-  local xml = mlist_to_table(mlist, style == 'display' and 2 or 0)
+  print''
+  local xml = process_mlist(mlist, style == 'display' and 2 or 0)
   print(write_xml(xml))
   -- print(write_xml(xml, '\n'))
-  print'\n'
+  print''
   return true
 end, 'dump_list')

test_tex.tex

@@ -1,6 +1,8 @@
 \documentclass{article}
-\usepackage{unicode-math}
+% \usepackage{unicode-math}
 \directlua{require'test_tex'}
+\RegisterFamilyMapping\symsymbols{oms}
+\RegisterFamilyMapping\symletters{oml}
 \begin{document}
 \[
   ax^2+b+c=0