Better stretchy handling and overwrite support

mlist_to_mml.lua

@@ -1,4 +1,7 @@
 local remap_comb = require'remap_comb'
+local stretchy = require'stretchy'
+
+local properties = node.get_properties_table()
 
 local noad_t, accent_t, style_t, choice_t = node.id'noad', node.id'accent', node.id'style', node.id'choice'
 local radical_t, fraction_t, fence_t = node.id'radical', node.id'fraction', node.id'fence'
@@ -17,18 +20,39 @@ local function sup_style(s) return s//4*2+4+s%2 end
 -- We ignore large_... since they aren't used for modern fonts
 local function delim_to_table(delim)
   if not delim then return end
+  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 }
+  return {[0] = 'mo', utf8.char(delim.small_char), ['tex:family'] = fam ~= 0 and fam or nil, stretchy = not stretchy[delim.small_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
+local function acc_to_table(acc, cur_style, stretch)
+  if not acc then return end
+  local props = properties[acc] props = props and props.mathml_table
+  if props then return props end
+  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
+  if stretch ~= not stretchy[char] then -- Handle nil gracefully in stretchy
+    stretch = nil
+  end
+  return {[0] = 'mo', char, ['tex:family'] = fam ~= 0 and fam or nil, stretchy = stretch}
 end
 
 local function kernel_to_table(kernel, cur_style)
   if not kernel then return end
+  local props = properties[kernel] props = props and props.mathml_table
+  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(kernel.char), ['tex:family'] = fam ~= 0 and fam or nil, mathvariant = char < 0x10000 and 'normal' or nil }
+    return {[0] = elem, utf8.char(char), ['tex:family'] = fam ~= 0 and fam or nil, mathvariant = 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
@@ -64,6 +88,7 @@ local function noad_to_table(noad, sub, cur_style)
       -- TODO
     else
       nucleus[0] = 'mo'
+      if stretchy[nucleus[1]] then nucleus.stretchy = false end
       if nucleus.mathvariant == 'normal' then nucleus.mathvariant = nil end
     end
     nucleus['tex:class'] = class
@@ -98,24 +123,8 @@ end
 
 local function accent_to_table(accent, sub, cur_style)
   local nucleus = kernel_to_table(accent.nucleus, cur_style//2*2+1)
-  local top_acc = kernel_to_table(accent.accent, cur_style)
+  local top_acc = acc_to_table(accent.accent, cur_style, sub & 1 == 1)
-  local bot_acc = kernel_to_table(accent.bot_accent, cur_style)
+  local bot_acc = acc_to_table(accent.bot_accent, cur_style, sub & 2 == 2)
-  if top_acc then
-    top_acc[0] = 'mo'
-    if top_acc.mathvariant == 'normal' then top_acc.mathvariant = nil end
-    if sub & 1 == 1 then
-      top_acc.stretchy = 'false'
-    end
-    top_acc[1] = remap_comb[top_acc[1]] or top_acc[1]
-  end
-  if bot_acc then
-    bot_acc[0] = 'mo'
-    if bot_acc.mathvariant == 'normal' then bot_acc.mathvariant = nil end
-    if sub & 2 == 2 then
-      bot_acc.stretchy = 'false'
-    end
-    bot_acc[1] = remap_comb[bot_acc[1]] or bot_acc[1]
-  end
   return {[0] = top_acc and (bot_acc and 'munderover' or 'mover') or 'munder',
     nucleus,
     bot_acc or top_acc,
@@ -145,7 +154,7 @@ local function radical_to_table(radical, sub, cur_style)
     elem = {[0] = 'msqrt', nucleus}
   elseif kind == 'uroot' then
     -- FIXME: Check that this is really a root
-    elem = {[0] = 'msqrt', nucleus, delim_to_table(radical.degree)}
+    elem = {[0] = 'msqrt', nucleus, kernel_to_table(radical.degree)}
   elseif kind == 'uunderdelimiter' then
     elem = {[0] = 'munder', left, nucleus}
   elseif kind == 'uoverdelimiter' then
@@ -189,7 +198,6 @@ end
 
 local function fence_to_table(fence, sub, cur_style)
   local delim = delim_to_table(fence.delimiter)
-  delim.stretchy = 'true'
   delim.fence = 'true'
   return delim
 end
@@ -198,7 +206,10 @@ function nodes_to_table(head, cur_style)
   local t = {[0] = "mrow"}
   local result = t
   for n, id, sub in node.traverse(head) do
-    if id == noad_t then
+    local props = properties[n] props = props and props.mathml_table
+    if props then
+      t[#t+1] = props
+    elseif id == noad_t then
       t[#t+1] = noad_to_table(n, sub, cur_style)
     elseif id == accent_t then
       t[#t+1] = accent_to_table(n, sub, cur_style)