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/**
* @file lualistener.cpp
* @author Nat Goodspeed
* @date 2024-02-06
* @brief Implementation for lualistener.
*
* $LicenseInfo:firstyear=2024&license=viewerlgpl$
* Copyright (c) 2024, Linden Research, Inc.
* $/LicenseInfo$
*/
// Precompiled header
#include "linden_common.h"
// associated header
#include "lualistener.h"
// STL headers
// std headers
#include <cstdlib> // std::rand()
#include <cstring> // std::memcpy()
// external library headers
#include "luau/lua.h"
// other Linden headers
#include "llerror.h"
#include "llleaplistener.h"
#include "lua_function.h"
LuaListener::LuaListener(lua_State* L):
super(getUniqueKey()),
mListener(
new LLLeapListener(
[L](LLEventPump& pump, const std::string& listener)
{ return connect(L, pump, listener); }))
{
mReplyConnection = connect(L, mReplyPump, "LuaListener");
}
LuaListener::~LuaListener()
{
LL_DEBUGS("Lua") << "~LuaListener('" << mReplyPump.getName() << "')" << LL_ENDL;
}
int LuaListener::getUniqueKey()
{
// Find a random key that does NOT already correspond to a LuaListener
// instance. Passing a duplicate key to LLInstanceTracker would do Bad
// Things.
int key;
do
{
key = std::rand();
} while (LuaListener::getInstance(key));
// This is theoretically racy, if we were instantiating new
// LuaListeners on multiple threads. Don't.
return key;
}
LLBoundListener LuaListener::connect(lua_State* L, LLEventPump& pump, const std::string& listener)
{
return pump.listen(
listener,
[L, pumpname=pump.getName()](const LLSD& data)
{ return call_lua(L, pumpname, data); });
}
bool LuaListener::call_lua(lua_State* L, const std::string& pump, const LLSD& data)
{
LL_INFOS("Lua") << "LuaListener::call_lua('" << pump << "', " << data << ")" << LL_ENDL;
if (! lua_checkstack(L, 3))
{
LL_WARNS("Lua") << "Cannot extend Lua stack to call listen_events() callback"
<< LL_ENDL;
return false;
}
// push the registered Lua callback function stored in our registry as
// "event.function"
lua_getfield(L, LUA_REGISTRYINDEX, "event.function");
llassert(lua_isfunction(L, -1));
// pass pump name
lua_pushstdstring(L, pump);
// then the data blob
lua_pushllsd(L, data);
// call the registered Lua listener function; allow it to return bool;
// no message handler
auto status = lua_pcall(L, 2, 1, 0);
bool result{ false };
if (status != LUA_OK)
{
LL_WARNS("Lua") << "Error in listen_events() callback: "
<< lua_tostdstring(L, -1) << LL_ENDL;
}
else
{
result = lua_toboolean(L, -1);
}
// discard either the error message or the bool return value
lua_pop(L, 1);
return result;
}
std::string LuaListener::getCommandName() const
{
return mListener->getPumpName();
}
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