From 81fdf41e3b04925dae7fe4629b5fd2b3913eb3cc Mon Sep 17 00:00:00 2001
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
Date: Sat, 26 Nov 2011 05:10:44 +0200
Subject: [PATCH] Lua: Add table _SYSTEM

---
 manual.lyx       |  9 +++++++++
 src/core/lua.cpp | 29 +++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/manual.lyx b/manual.lyx
index 8a05e35c..8398605a 100644
--- a/manual.lyx
+++ b/manual.lyx
@@ -2583,6 +2583,15 @@ Writes the specified value (negative values undergo 2's complement) to specified
 \end_layout
 
 \begin_layout Subsection
+Table _SYSTEM
+\end_layout
+
+\begin_layout Standard
+Contains copy of global variables from time of Lua initialization.
+ Non-writeable.
+\end_layout
+
+\begin_layout Subsection
 Callbacks
 \end_layout
 
diff --git a/src/core/lua.cpp b/src/core/lua.cpp
index 26def20c..9d28f428 100644
--- a/src/core/lua.cpp
+++ b/src/core/lua.cpp
@@ -283,6 +283,34 @@ namespace
 			command::invokeC("repaint");
 		}
 	}
+
+	int system_write_error(lua_State* L)
+	{
+		lua_pushstring(L, "_SYSTEM is write-protected");
+		lua_error(L);
+		return 0;
+	}
+
+	void copy_system_tables(lua_State* L)
+	{
+		lua_newtable(L);
+		lua_pushnil(L);
+		while(lua_next(L, LUA_GLOBALSINDEX)) {
+			//Stack: _SYSTEM, KEY, VALUE
+			lua_pushvalue(L, -2);
+			lua_pushvalue(L, -2);
+			//Stack: _SYSTEM, KEY, VALUE, KEY, VALUE
+			lua_rawset(L, -5);
+			//Stack: _SYSTEM, KEY, VALUE
+			lua_pop(L, 1);
+			//Stack: _SYSTEM, KEY
+		}
+		lua_newtable(L);
+		lua_pushcfunction(L, system_write_error);
+		lua_setfield(L, -2, "__newindex");
+		lua_setmetatable(L, -2);
+		lua_setglobal(L, "_SYSTEM");
+	}
 }
 
 void lua_callback_do_paint(struct lua_render_context* ctx) throw()
@@ -438,6 +466,7 @@ void init_lua() throw()
 	luaL_openlibs(L);
 
 	register_lua_functions(L);
+	copy_system_tables(L);
 }
 
 bool lua_requests_repaint = false;
-- 
2.11.4.GIT