From d4c53f5bdf8e0bb716ef21847306ab24c8e67d3a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcel=20Fabian=20Kr=C3=BCger?= <tex@2krueger.de>
Date: Mon, 28 Feb 2022 11:59:15 +0100
Subject: [PATCH] Add node.current_latelua

---
 manual/luatex-nodes.tex                    | 12 ++++++++++
 source/texk/web2c/luatexdir/lua/lnodelib.c | 26 ++++++++++++++++++++++
 source/texk/web2c/luatexdir/lua/luastuff.c |  6 +++++
 3 files changed, 44 insertions(+)

diff --git a/manual/luatex-nodes.tex b/manual/luatex-nodes.tex
index 5a48b4c18..aaff0a38c 100644
--- a/manual/luatex-nodes.tex
+++ b/manual/luatex-nodes.tex
@@ -1421,6 +1421,18 @@ attribute list, not a copy thereof. Therefore, changing any of the attributes in
 the list will change these values for all nodes that have the current attribute
 list assigned to them.
 
+\subsection{\type {current_latelua}}
+
+\libindex{current_latelua}
+
+When called directly or indirectly from a \type{late_lua} whatsit, return the
+whatsit node which triggered this execution.
+
+\startfunctioncall
+<node> m =
+    node.current_latelua()
+\stopfunctioncall
+
 \subsection{\type {hpack}}
 
 \libindex {hpack}
diff --git a/source/texk/web2c/luatexdir/lua/lnodelib.c b/source/texk/web2c/luatexdir/lua/lnodelib.c
index 1ff36bc95..84bccee60 100644
--- a/source/texk/web2c/luatexdir/lua/lnodelib.c
+++ b/source/texk/web2c/luatexdir/lua/lnodelib.c
@@ -6541,6 +6541,30 @@ static int lua_nodelib_direct_currentattr(lua_State * L)
 }
 
 
+/* Defined in luastuff.c */
+extern halfword current_latelua;
+
+/* node.current_latelua(node m) */
+
+static int lua_nodelib_currentlatelua(lua_State * L)
+{
+    lua_nodelib_push_fast(L, current_latelua);
+    return 1;
+}
+
+
+/* node.direct.current_latelua() */
+
+static int lua_nodelib_direct_currentlatelua(lua_State * L)
+{
+    if (current_latelua)
+        lua_pushinteger(L, current_latelua);
+    else
+        lua_pushnil(L);
+    return 1;
+}
+
+
 /* node.direct.todirect */
 
 static int lua_nodelib_direct_todirect(lua_State * L)
@@ -8890,6 +8914,7 @@ static const struct luaL_Reg direct_nodelib_f[] = {
     {"copy_list", lua_nodelib_direct_copy_list},
     {"count", lua_nodelib_direct_count},
     {"current_attr", lua_nodelib_direct_currentattr},
+    {"current_latelua", lua_nodelib_direct_currentlatelua},
     {"dimensions", lua_nodelib_direct_dimensions},
     {"rangedimensions", lua_nodelib_direct_rangedimensions},
  /* {"do_ligature_n", lua_nodelib_direct_do_ligature_n}, */
@@ -9036,6 +9061,7 @@ static const struct luaL_Reg nodelib_f[] = {
     {"copy_list", lua_nodelib_copy_list},
     {"count", lua_nodelib_count},
     {"current_attr", lua_nodelib_currentattr},
+    {"current_latelua", lua_nodelib_currentlatelua},
     {"dimensions", lua_nodelib_dimensions},
     {"rangedimensions", lua_nodelib_rangedimensions},
  /* {"do_ligature_n", lua_nodelib_do_ligature_n}, */
diff --git a/source/texk/web2c/luatexdir/lua/luastuff.c b/source/texk/web2c/luatexdir/lua/luastuff.c
index fb05c60dd..469074d8c 100644
--- a/source/texk/web2c/luatexdir/lua/luastuff.c
+++ b/source/texk/web2c/luatexdir/lua/luastuff.c
@@ -32,6 +32,8 @@ lua_State *Luas = NULL;
 int luastate_bytes = 0;
 int lua_active = 0;
 
+halfword current_latelua = null;
+
 #ifdef LuajitTeX
 #define Luas_load(Luas,getS,ls,lua_id) \
     lua_load(Luas,getS,ls,lua_id);
@@ -594,8 +596,11 @@ void luacall_vf(int p, int f, int c)
 
 void late_lua(PDF pdf, halfword p)
 {
+    halfword saved;
     halfword t;
     (void) pdf;
+    saved = current_latelua;
+    current_latelua = p;
     t = late_lua_type(p);
     if (t == normal) {
         /*tex sets |def_ref| */
@@ -609,6 +614,7 @@ void late_lua(PDF pdf, halfword p)
     } else {
         /*tex Let's just ignore it, could be some user specific thing. */
     }
+    current_latelua = saved;
 }
 
 void luatokencall(int p, int nameptr)
-- 
2.35.1