Lua: loopwarapper

manual.lyx

@@ -1817,6 +1817,53 @@ bus_address(number snesaddr)
 Returns virtual address corresponding to specified address on SNES bus.
 \end_layout
 
+\begin_layout Subsubsection
+loopwrapper(function fun, ...)
+\end_layout
+
+\begin_layout Standard
+Calls function fun with function and specified arguments.
+ The function passed suspends execution until the function returned is called.
+ Handy for linear flow control among multiple invocations of a hook.
+ Example code:
+\end_layout
+
+\begin_layout LyX-Code
+on_paint = loopwrapper(function(wait)
+\end_layout
+
+\begin_deeper
+\begin_layout LyX-Code
+while true do
+\end_layout
+
+\begin_deeper
+\begin_layout LyX-Code
+gui.text(0, 0, 
+\begin_inset Quotes eld
+\end_inset
+
+Test!
+\begin_inset Quotes erd
+\end_inset
+
+);
+\end_layout
+
+\begin_layout LyX-Code
+wait();
+\end_layout
+
+\end_deeper
+\begin_layout LyX-Code
+end
+\end_layout
+
+\end_deeper
+\begin_layout LyX-Code
+end);
+\end_layout
+
 \begin_layout Subsection
 Table bit:
 \end_layout

manual.txt

@@ -886,6 +886,25 @@ has expired, on_timer() will be called once.
 Returns virtual address corresponding to specified address on 
 SNES bus.
 
+8.1.8 loopwrapper(function fun, ...)
+
+Calls function fun with function and specified arguments. The 
+function passed suspends execution until the function returned is 
+called. Handy for linear flow control among multiple invocations 
+of a hook. Example code:
+
+on_paint = loopwrapper(function(wait)
+
+  while true do
+
+    gui.text(0, 0, “Test!”);
+
+    wait();
+
+  end
+
+end);
+
 8.2 Table bit:
 
 Bitwise logical functions and related.

src/lua/lua.cpp

@@ -19,6 +19,7 @@ extern "C" {
 
 uint64_t lua_idle_hook_time = 0x7EFFFFFFFFFFFFFFULL;
 uint64_t lua_timer_hook_time = 0x7EFFFFFFFFFFFFFFULL;
+extern const char* lua_sysrc_script;
 
 namespace
 {
@@ -338,6 +339,12 @@ namespace
 		lua_setmetatable(L, -2);
 		lua_setglobal(L, "_SYSTEM");
 	}
+
+	void run_sysrc_lua(lua_State* L)
+	{
+		do_eval_lua(lua_sysrc_script);
+	}
+
 }
 
 void lua_callback_do_paint(struct lua_render_context* ctx, bool non_synthetic) throw()
@@ -552,6 +559,7 @@ void init_lua(bool soft) throw()
 	luaL_openlibs(L);
 
 	register_lua_functions(L);
+	run_sysrc_lua(L);
 	copy_system_tables(L);
 }
 

src/lua/sysrc.cpp

@@ -0,0 +1,18 @@
+const char* lua_sysrc_script =
+"loopwrapper = function(fn, ...)\n"
+"	local routine = coroutine.create(fn);\n"
+"	local resume = function(...)\n"
+"		if coroutine.status(routine) ~= \"dead\" then\n"
+"			local x, y;\n"
+"			x, y = coroutine.resume(routine, ...);\n"
+"			if not x then\n"
+"				error(y);\n"
+"			end\n"
+"		end\n"
+"	end\n"
+"	local yield = function()\n"
+"		return coroutine.yield(routine);\n"
+"	end\n"
+"	resume(yield, ...);\n"
+"	return resume;\n"
+"end\n";