GameCodingCompleteLinux/Source/GCC4/LUAScripting/LuaStateManager.cpp

// GameCode4 is the sample application that encapsulates much of the source code
// discussed in "Game Coding Complete - 4th Edition" by Mike McShaffry and David
// "Rez" Graham, published by Charles River Media. 
// ISBN-10: 1133776574 | ISBN-13: 978-1133776574
//
// If this source code has found it's way to you, and you think it has helped you
// in any way, do the authors a favor and buy a new copy of the book - there are 
// detailed explanations in it that compliment this code well. Buy a copy at Amazon.com
// by clicking here: 
//    http://www.amazon.com/gp/product/1133776574/ref=olp_product_details?ie=UTF8&me=&seller=
//
// There's a companion web site at http://www.mcshaffry.com/GameCode/
// 
// The source code is managed and maintained through Google Code: 
//    http://code.google.com/p/gamecode4/
//
// (c) Copyright 2012 Michael L. McShaffry and David Graham
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser GPL v3
// as published by the Free Software Foundation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See 
// http://www.gnu.org/licenses/lgpl-3.0.txt for more details.
//
// You should have received a copy of the GNU Lesser GPL v3
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
//========================================================================

#include "LuaStateManager.h"
#include "../Unix/GameCodeStd.h"
#include "../Debugging/Logger.h"
#include "../Utilities/String.h"

LuaStateManager* LuaStateManager::s_pSingleton = NULL;

bool LuaStateManager::Create(void)
{
	if (s_pSingleton)
	{
		GCC_ERROR("Overwriting LuaStateManager singleton");
		SAFE_DELETE(s_pSingleton);
	}

	s_pSingleton = GCC_NEW LuaStateManager;
	if (s_pSingleton)
		return s_pSingleton->VInit();

	return false;
}

void LuaStateManager::Destroy(void)
{
	GCC_ASSERT(s_pSingleton);
	SAFE_DELETE(s_pSingleton);
}

bool LuaStateManager::VInit(void)
{
	m_luaState.open_libraries(sol::lib::base);

	// // register functions
	m_luaState["ExecuteFile"] = [this](const std::string& path) { 
		return this->VExecuteFile(path.c_str()); 
	};

	m_luaState["ExecuteString"] = [this](const std::string& chunk) { 
		return this->VExecuteString(chunk.c_str()); 
	};

	return true;
}

void LuaStateManager::VExecuteFile(const char* path)
{
	try
	{
		auto result = m_luaState.script_file(path);
	}
	catch(sol::error const& err)
	{
		SetError(err);
	}
}

void LuaStateManager::VExecuteString(const char* chunk)
{
	try
	{
		// Most strings are passed straight through to the Lua interpreter
		if (strlen(chunk) <= 1 || chunk[0] != '=')
		{
			m_luaState.script(chunk);
		}
		else // If the string starts with '=', wrap the statement in the print() function.
		{
			std::string buffer("print(");
			buffer += (chunk + 1);
			buffer += ")";
			m_luaState.script(buffer);
		}
	}
	catch(sol::error const& err)
	{
		SetError(err);
	}
}

void LuaStateManager::SetError(sol::error const& err)
{
    m_lastError = err.what();
    GCC_ERROR(m_lastError);
}

sol::global_table LuaStateManager::GetGlobalVars(void)
{
	return m_luaState.globals();
}

sol::state_view LuaStateManager::GetLuaState(void)
{
	return m_luaState;
}

sol::table LuaStateManager::CreatePath(const char* pathString, bool toIgnoreLastElement)
{
	StringVec splitPath;
	Split(pathString, splitPath, '.');
	if (toIgnoreLastElement)
		splitPath.pop_back();

	sol::table context = GetGlobalVars();
	for (auto it=splitPath.begin(); it != splitPath.end(); ++it)
	{
		// make sure we still have a valid context
		if (context == sol::lua_nil)
		{
			GCC_ERROR("Something broke in CreatePath(); bailing out (element == " + (*it) + ")");
			return context; // this will be nil
		}

		// grab whatever exists for this element
		const std::string& element = (*it);
		sol::object curr = context[element];

		if (!curr.is<sol::table>())
		{
			// if the element is not a table and not nil, we clobber it
			if (curr != sol::lua_nil)
			{
				GCC_WARNING("Overwriting element '" + element + "' in table");
				context[element] = sol::lua_nil;
			}

			context[element] = sol::state_view(context.lua_state()).create_table();
		}

		context = context[element];
	}

	return context;
}