Luapath

Luapath is a small C++ library that can load and traverse .lua files.

Usage

Let's say we have the following lua file called test.lua:

skinnedModels = {
barbarian = {
		modelDir = "models/barbarian/exported/barbarian7.dae",
		vertexShader = "skinning",
		fragmentShader = "texture_d",
		animationName = "wait",
		additionalAnimations = {
			{animationName = "dance" , fileDir = "models/barbarian/exported/animations/dance.dae"},
			{animationName = "run" , fileDir = "models/barbarian/exported/animations/run.dae"},
			{animationName = "walk" , fileDir = "models/barbarian/exported/animations/walk.dae"},
			{animationName = "lie" , fileDir = "models/barbarian/exported/animations/lie.dae"},
		},
		aabb = {
			min = {x = -0.5, y = 0.0, z = -0.5},
			max = {x = 0.5, y = 2.2, z = 0.5}
		}
	},

Load file

#include <luapath/luapath.hpp>
...
luapath::LuaState myfile("test.lua");

If the file can't be loaded a lua_state_exception exception is thrown.

Traversal

Traversing the file is very easy. "." is used to traverse string keys and "#" is used to traverse number keys. If there is an error traversing a path_lookup_exception exception is thrown.

The function getValue returns either a string, int or a float depending on what C++ value we are trying to cast the lua value to. If it can't cast to the desired type a type_mismatch_exception exception is thrown.

The function getGlobalTable returns a Table object by searching the top most level of the file.

The function getTable returns an intermediary table.

For example if we want to get the vertex shader of the barbarian we do:

std::string shader;
shader = myfile.getGlobalTable("skinnedModels").getValue(".barbarian.vertexShader");

and if we wanted to get the second additional animation:

std::string anim;
anim = myfile.getGlobalTable("skinnedModels").getValue(".barbarian.additionalAnimations#2");

also we can play around with intermediary table so we don't have to repeat long sequences:

luapath::Table models;
model = myfile.getGlobalTable("skinnedModels");
luapath::Table currModel = models.getTable(".barbarian");
std::string shader = currModel.getValue(".vertexShader");
std::string anim = currModel.getValue(".additionalAnimations#2");

sometimes we are not sure if a key even exists. For example if we wanted to iterate over the "additionalAnimations" table until the end we can do the following:

luapath::Table additionalAnimTable = currModel.getTable(".additionalAnimations");
int additionalAnimNum = 1; // lua indexing is not 0 based
luapath::Table currAnim;
while (additionalAnimTable.getTable(string("#") + std::to_string(additionalAnimNum), currAnim))
{
    //do something cool
    //
	additionalAnimNum++;
}

Installation

Include the include folder for the header files. The library has a dependency on the lua C++ library so you need to include and link against it too. It is available under the 3rdparty folder.

Alternatively, if you use CMake you can add the following to your Cmake file:

add_subdirectory(${DEVLIB_DIR}/luapath "luapath")
include_directories(${LUAPATH_INCLUDE_DIR})
target_link_libraries(${APP_NAME} ${LUAPATH_LIBRARIES})

To Do