From 174cad050b1f6a4be1ff93f4e7e25363c4e84fe9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcel=20Fabian=20Kr=C3=BCger?= <tex@2krueger.de>
Date: Wed, 20 Dec 2023 19:22:21 +0100
Subject: [PATCH] Add LaTeX hook to intercept converted MathML

---
 luamml-tex.lua       | 25 +++++++++++++++++++++++--
 luamml-xmlwriter.lua |  2 +-
 luamml.dtx           | 19 +++++++++++++++++--
 3 files changed, 41 insertions(+), 5 deletions(-)

diff --git a/luamml-tex.lua b/luamml-tex.lua
index c391a0a..7c069c8 100644
--- a/luamml-tex.lua
+++ b/luamml-tex.lua
@@ -10,6 +10,10 @@ local write_struct = require'luamml-structelemwriter'
 
 local filename_token = token.create'l__luamml_filename_tl'
 local label_token = token.create'l__luamml_label_tl'
+local left_brace = token.new(string.byte'{', 1)
+local right_brace = token.new(string.byte'}', 2)
+
+local output_hook_token
 
 local properties = node.get_properties_table()
 local mmode, hmode, vmode do
@@ -92,6 +96,11 @@ local function save_result(xml, display, structelem)
   if tracing then
     texio.write_nl(write_xml(mlist_result) .. '\n')
   end
+  if output_hook_token then
+    tex.runtoks(function()
+      tex.sprint(-2, output_hook_token, left_brace, write_xml(mlist_result), right_brace)
+    end)
+  end
   if tex.count.l__luamml_flag_int & 8 == 8 then
     write_struct(mlist_result)
   end
@@ -166,7 +175,7 @@ lua.get_functions_table()[funcid] = function()
 end
 
 funcid = luatexbase.new_luafunction'luamml_begin_single_file:'
-token.set_lua('luamml_begin_single_file:', funcid, protected)
+token.set_lua('luamml_begin_single_file:', funcid, 'protected')
 lua.get_functions_table()[funcid] = function()
   token.put_next(filename_token)
   local filename = token.scan_argument()
@@ -176,7 +185,7 @@ lua.get_functions_table()[funcid] = function()
 end
 
 funcid = luatexbase.new_luafunction'luamml_end_single_file:'
-token.set_lua('luamml_end_single_file:', funcid, protected)
+token.set_lua('luamml_end_single_file:', funcid, 'protected')
 lua.get_functions_table()[funcid] = function()
   if out_file then
     out_file:close()
@@ -184,6 +193,18 @@ lua.get_functions_table()[funcid] = function()
   end
 end
 
+funcid = luatexbase.new_luafunction'luamml_register_output_hook:N'
+token.set_lua('__luamml_register_output_hook:N', funcid, 'protected')
+lua.get_functions_table()[funcid] = function()
+  output_hook_token = token.get_next()
+end
+
+funcid = luatexbase.new_luafunction'luamml_disable_output_hook:'
+token.set_lua('__luamml_disable_output_hook:', funcid, 'protected')
+lua.get_functions_table()[funcid] = function()
+  output_hook_token = nil
+end
+
 local annotate_context = require'luamml-tex-annotate'
 annotate_context.data.mathml = labelled_mathml
 
diff --git a/luamml-xmlwriter.lua b/luamml-xmlwriter.lua
index 47d4385..c68b79a 100644
--- a/luamml-xmlwriter.lua
+++ b/luamml-xmlwriter.lua
@@ -10,7 +10,7 @@ local escapes = {
   ['&'] = "&amp;",
 }
 local function escape_text(text)
-  return string.gsub(string.gsub(tostring(text), '["<>&]', escapes), '[\x00-\x08\x0B\x0C\x0E-\x20]', function(x)
+  return string.gsub(string.gsub(tostring(text), '["<>&]', escapes), '[\x00-\x08\x0B\x0C\x0E-\x1F]', function(x)
     return string.format('^^%02x', string.byte(x))
   end)
 end
diff --git a/luamml.dtx b/luamml.dtx
index 72b9561..5c18f49 100644
--- a/luamml.dtx
+++ b/luamml.dtx
@@ -99,6 +99,21 @@
 %    \begin{macrocode}
 %<luatex>\lua_now:n { require'luamml-tex' }
 %    \end{macrocode}
+%
+% \subsection{Hook}
+% We also call a hook with arguments at the end of every MathML conversion with the result.
+% Currently only implemented in Lua\TeX{} since it immediately provides the output.
+%    \begin{macrocode}
+%<*luatex>
+\hook_new_with_args:nn { luamml / converted } { 1 }
+
+\cs_new_protected:Npn \__luamml_output_hook:n {
+  \hook_use:nnw { luamml / converted } { 1 }
+}
+\__luamml_register_output_hook:N \__luamml_output_hook:n
+%</luatex>
+%    \end{macrocode}
+
 %
 % \subsection{Flags}
 % The most important interface is for setting the flag which controls how the
@@ -259,7 +274,7 @@
 \cs_new_protected:Npn \luamml_annotate:nen #1#2#3 {
   \__luamml_annotate_begin:
     #3
-    \__luamml_annotate_end:we \tex_numexpr:D #1 \scan_stop: {#2}
+  \__luamml_annotate_end:we \tex_numexpr:D #1 \scan_stop: {#2}
 }
 
 \cs_new_protected:Npn \luamml_annotate:en #1#2 {
@@ -434,7 +449,7 @@
 %    \begin{macrocode}
 \cs_new_protected:Npn \__luamml_patch_package:nn #1 #2 {
   \@ifpackageloaded {#1} {#2} {
-    \hook_gput_code:nnn {package/after/#1} {luamml} {#2}
+    \hook_gput_code:nnn {package/#1/after} {luamml} {#2}
   }
 }
 \cs_new_protected:Npn \__luamml_patch_package:n #1 {