Added love.event.addListener and removeListener.

addListener takes a function, and names of events that will trigger the function when they're processed inside love.event.poll or love.event.wait. When the given listener function is called, the name of the event as well as all of the event's arguments are passed to the function.

If addListener is called multiple times with the same function and events, it will not add the function more than once.

removeListener takes a function and removes it from all events it was previously added to.

platform/xcode/liblove.xcodeproj/project.pbxproj

@@ -920,6 +920,7 @@
 
 /* Begin PBXFileReference section */
 		503971A86B7167A91B670FBA /* boot.lua.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = boot.lua.h; sourceTree = "<group>"; };
+		FA024C1C1C0D81CD00567EB0 /* wrap_Event.lua */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text; path = wrap_Event.lua; sourceTree = "<group>"; };
 		FA08F5AE16C7525600F007B5 /* liblove-macosx.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = "liblove-macosx.plist"; path = "macosx/liblove-macosx.plist"; sourceTree = "<group>"; };
 		FA0B78DD1A958B90000E1D17 /* liblove.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = liblove.a; sourceTree = BUILT_PRODUCTS_DIR; };
 		FA0B78F71A958E3B000E1D17 /* b64.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = b64.cpp; sourceTree = "<group>"; };
@@ -2170,6 +2171,7 @@
 				FA0B7B551A95902C000E1D17 /* sdl */,
 				FA8951A01AA2EDF300EC385A /* wrap_Event.cpp */,
 				FA8951A11AA2EDF300EC385A /* wrap_Event.h */,
+				FA024C1C1C0D81CD00567EB0 /* wrap_Event.lua */,
 			);
 			path = event;
 			sourceTree = "<group>";

src/common/runtime.cpp

@@ -243,7 +243,17 @@ int luax_register_module(lua_State *L, const WrappedModule &m)
 
 	// Register all the functions.
 	if (m.functions != nullptr)
-		luax_setfuncs(L, m.functions);
+	{
+		const luaL_Reg *l = m.functions;
+
+		for (; l->name != nullptr; l++)
+		{
+			// Set the module's table as an upvalue for the module's functions.
+			lua_pushvalue(L, -1);
+			lua_pushcclosure(L, l->func, 1);
+			lua_setfield(L, -2, l->name);
+		}
+	}
 
 	// Register types.
 	if (m.types != nullptr)

src/modules/event/Event.h

@@ -49,6 +49,8 @@ public:
 	int toLua(lua_State *L);
 	static Message *fromLua(lua_State *L, int n);
 
+	const std::string &getName() const { return name; }
+
 private:
 
 	std::string name;

src/modules/event/wrap_Event.cpp

@@ -25,6 +25,11 @@
 
 #include "sdl/Event.h"
 
+// Put the Lua code directly into a raw string literal.
+static const char event_lua[] =
+#include "wrap_Event.lua"
+;
+
 namespace love
 {
 namespace event
@@ -32,55 +37,82 @@ namespace event
 
 #define instance() (Module::getInstance<Event>(Module::M_EVENT))
 
-static int poll_i(lua_State *L)
-{
-	Message *m;
+static const char *listenersKey = "_listeners";
 
-	while (instance()->poll(m))
+static int processMessage(lua_State *L, Message *m)
+{
+	if (m == nullptr)
+		return 0;
+
+	int args = m->toLua(L);
+
+	// Push the love.event[listenersKey][eventname] table onto the stack.
+	lua_getfield(L, lua_upvalueindex(1), listenersKey);
+	lua_getfield(L, -1, m->getName().c_str());
+
+	if (lua_istable(L, -1))
 	{
-		int args = m->toLua(L);
-		m->release();
-		return args;
+		int len = (int) luax_objlen(L, -1);
+
+		// Each array entry in the table is a listener function we should call.
+		for (int i = 1; i <= len; i++)
+		{
+			lua_rawgeti(L, -1, i);
+
+			// Push all message args (including the event name), in order.
+			for (int j = 1; j <= args; j++)
+				lua_pushvalue(L, -(args + 3));
+
+			lua_call(L, args, 0);
+		}
 	}
 
+	lua_pop(L, 2);
+
+	m->release();
+
+	// Leave the message's args on the stack.
+	return args;
+}
+
+static int w_poll_i(lua_State *L)
+{
+	Message *m = nullptr;
+
+	if (instance()->poll(m))
+		return processMessage(L, m);
+
 	// No pending events.
 	return 0;
 }
 
+int w_poll(lua_State *L)
+{
+	// w_poll_i needs access to the love.event table via an upvalue.
+	lua_pushvalue(L, lua_upvalueindex(1));
+	lua_pushcclosure(L, w_poll_i, 1);
+	return 1;
+}
+
 int w_pump(lua_State *)
 {
 	instance()->pump();
 	return 0;
 }
 
-int w_poll(lua_State *L)
-{
-	lua_pushcclosure(L, &poll_i, 0);
-	return 1;
-}
-
 int w_wait(lua_State *L)
 {
-	Message *m;
-
-	if ((m = instance()->wait()))
-	{
-		int args = m->toLua(L);
-		m->release();
-		return args;
-	}
-
-	return 0;
+	Message *m = instance()->wait();
+	return processMessage(L, m);
 }
 
 int w_push(lua_State *L)
 {
-	Message *m;
+	Message *m = Message::fromLua(L, 1);
 
-	bool success = (m = Message::fromLua(L, 1)) != NULL;
-	luax_pushboolean(L, success);
+	luax_pushboolean(L, m != nullptr);
 
-	if (!success)
+	if (m == nullptr)
 		return 1;
 
 	instance()->push(m);
@@ -117,6 +149,7 @@ int w_quit(lua_State *L)
 // List of functions to wrap.
 static const luaL_Reg functions[] =
 {
+	// addListener and removeListener are defined in wrap_Event.lua
 	{ "pump", w_pump },
 	{ "poll", w_poll },
 	{ "wait", w_wait },
@@ -143,7 +176,19 @@ extern "C" int luaopen_love_event(lua_State *L)
 	w.functions = functions;
 	w.types = nullptr;
 
-	return luax_register_module(L, w);
+	int ret = luax_register_module(L, w);
+
+	// love.event[listenersKey] = {}
+	lua_newtable(L);
+	lua_setfield(L, -2, listenersKey);
+
+	// Execute wrap_Event.lua, sending the event and listeners tables as args.
+	luaL_loadbuffer(L, event_lua, sizeof(event_lua), "wrap_Event.lua");
+	lua_pushvalue(L, -2);
+	lua_getfield(L, -1, listenersKey);
+	lua_call(L, 2, 0);
+
+	return ret;
 }
 
 } // event

src/modules/event/wrap_Event.lua

@@ -0,0 +1,97 @@
+R"luastring"--(
+-- DO NOT REMOVE THE ABOVE LINE. It is used to load this file as a C++ string.
+-- There is a matching delimiter at the bottom of the file.
+
+--[[
+Copyright (c) 2006-2015 LOVE Development Team
+
+This software is provided 'as-is', without any express or implied
+warranty.  In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not
+claim that you wrote the original software. If you use this software
+in a product, an acknowledgment in the product documentation would be
+appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be
+misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+--]]
+
+local event, listeners = ...
+
+local type, select, error = type, select, error
+local pairs, ipairs = pairs, ipairs
+local table_insert, table_remove = table.insert, table.remove
+local max = math.max
+
+local function addListenerForEvent(event, func)
+	listeners[event] = listeners[event] or {}
+
+	-- Don't add a function to the event's array more than once.
+	for i,v in ipairs(listeners[event]) do
+		if v == func then
+			return
+		end
+	end
+
+	table_insert(listeners[event], func)
+end
+
+function event.addListener(func, ...)
+	if type(func) ~= "function" then
+		error("Invalid argument #1 to addListener (expected function)", 2)
+	end
+
+	local t = (...)
+	if type(t) == "table" then
+		for i, name in ipairs(t) do
+			if type(name) ~= "string" then
+				error("Invalid table element #"..i.." in argument #2 to love.event.addListener (expected string)", 2)
+			end
+
+			addListenerForEvent(name, func)
+		end
+	else
+		local n = select("#", ...)
+		for i = 1, max(n, 1) do
+			local name = select(i, ...)
+
+			if type(name) ~= "string" then
+				error("Invalid argument #"..(i+1).." to addListener (expected string)", 2)
+			end
+
+			addListenerForEvent(name, func)
+		end
+	end
+
+	return func
+end
+
+function event.removeListener(func)
+	if type(func) ~= "function" then
+		error("Invalid argument #1 to removeListener (expected function)", 2)
+	end
+
+	local success = false
+
+	-- Remove the listener function from all event names it was subscribed to.
+	for eventname, eventlisteners in pairs(listeners) do
+		for i=#eventlisteners, 1, -1 do
+			if eventlisteners[i] == func then
+				table_remove(eventlisteners, i)
+				success = true
+				break
+			end
+		end
+	end
+
+	return success
+end
+
+-- DO NOT REMOVE THE NEXT LINE. It is used to load this file as a C++ string.
+--)luastring"--"