From b3bd3805961c05776c7f398ce98082effebd8ca2 Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavelo@centrum.sk>
Date: Fri, 8 Jul 2011 00:24:40 +0200
Subject: A lightweight version of lua::state::pushclosure which handles the
 simple cases

---
 src/FbTk/Luamm.cc | 12 ++++++++++--
 src/FbTk/Luamm.hh |  3 ++-
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/FbTk/Luamm.cc b/src/FbTk/Luamm.cc
index 563be9c..1ef751f 100644
--- a/src/FbTk/Luamm.cc
+++ b/src/FbTk/Luamm.cc
@@ -59,6 +59,7 @@ namespace lua {
             lua_rawset(l, index);
         }
 
+        template<typename Functor>
         int closure_trampoline(lua_State *l)
         {
             lua_checkstack(l, 2);
@@ -68,7 +69,7 @@ namespace lua {
             lua_pop(l, 1);
 
             try {
-                Slot *fn = static_cast<Slot *>( L->touserdata(lua_upvalueindex(1)) );
+                Functor *fn = reinterpret_cast<Functor *>( L->touserdata(lua_upvalueindex(1)) );
                 assert(fn);
                 return (*fn)(L);
             }
@@ -390,7 +391,14 @@ namespace lua {
         setmetatable(-2);
 
         insert(-n-1);
-        lua_pushcclosure(cobj, &closure_trampoline, n+1);
+        lua_pushcclosure(cobj, &closure_trampoline<Slot>, n+1);
+    }
+
+    void state::pushclosure(int (*fn)(state *), int n)
+    {
+        pushlightuserdata(reinterpret_cast<void *>(fn));
+        insert(-n-1);
+        lua_pushcclosure(cobj, &closure_trampoline<int (state *)>, n+1);
     }
 
     void state::rawgetfield(int index, const char *k) throw(std::bad_alloc)
diff --git a/src/FbTk/Luamm.hh b/src/FbTk/Luamm.hh
index 05cb569..96a5eea 100644
--- a/src/FbTk/Luamm.hh
+++ b/src/FbTk/Luamm.hh
@@ -237,9 +237,10 @@ namespace lua {
         void newtable() { lua_newtable(cobj); }
         void *newuserdata(size_t size) { return lua_newuserdata(cobj, size); }
         // Functor can be anything that FbTk::Slot can handle, everything else remains
-        // identical
+        // identical. We also provide a specialized, lightweight version for simple functors
         template<typename Functor>
         void pushclosure(const Functor &fn, int n);
+        void pushclosure(int (*fn)(state *), int n);
         template<typename Functor>
         void pushfunction(const Functor &fn) { pushclosure(fn, 0); }
         void pushstring(const char *s) { lua_pushstring(cobj, s); }
-- 
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