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README
td_rlua
This library is a high-level binding for Lua 5.3. You don't have access to the Lua stack, all you can do is read/write variables (including callbacks) and execute Lua code.
How to install it?
Add this to the Cargo.toml
file of your project
[dependencies]
td_rlua = "0.1.0"
How to use it?
extern crate td_rlua;
use td_rlua::Lua;
The Lua
struct is the main element of this library. It represents a context in which you can execute Lua code.
let mut lua = Lua::new(); // mutable is mandatory
Reading and writing variables
lua.set("x", 2);
let _: () = lua.exec_string("x = x + 1").unwrap();
let x: i32 = lua.query("x").unwrap();
assert_eq!(x, 3);
Reading and writing global variables of the Lua context can be done with set
and query
.
The query
function returns an Option<T>
and does a copy of the value.
The base types that can be read and written are: i8
, i16
, i32
, u8
, u16
, u32
, f32
, f64
, bool
, String
. &str
can be written but not read.
If you wish so, you can also add other types by implementing the LuaPush
and LuaRead
traits.
Executing Lua
let x: u32 = lua.exec_string("return 6 * 2;").unwrap(); // equals 12
The exec_string
function takes a &str
and returns a Option<T>
where T: LuaRead
.
Writing functions
In order to write a function, you must wrap it around td_rlua::functionX
where X
is the number of parameters. This is for the moment a limitation of Rust's inferrence system.
fn add(a: i32, b: i32) -> i32 {
a + b
}
lua.set("add", td_rlua::function2(add));
let _: () = lua.exec_string("c = add(2, 4)").unwrap(); // calls the `add` function above
let c: i32 = lua.query("c").unwrap();
assert_eq!(c, 6);
In Lua, functions are exactly like regular variables.
You can write regular functions as well as closures:
lua.set("mul", td_rlua::function2(|a: i32, b: i32| a * b));
Note that the lifetime of the Lua context must be equal to or shorter than the lifetime of closures. This is enforced at compile-time.
let mut a = 5i;
{
let mut lua = Lua::new();
lua.set("inc", || a += 1); // borrows 'a'
for i in (0 .. 15) {
let _: () = lua.exec_string("inc()").unwrap();
}
} // unborrows `a`
assert_eq!(a, 20)
Error handling
extern "C" fn error_handle(lua: *mut c_lua::lua_State) -> libc::c_int {
let err = unsafe { c_lua::lua_tostring(lua, -1) };
let err = unsafe { CStr::from_ptr(err) };
let err = String::from_utf8(err.to_bytes().to_vec()).unwrap();
println!("error:{}", err);
0
}
lua.register("error_handle", error_handle);
Default in exec_string will call pcall, and set the error_function _G["error_handle"] so you can reset 'error_handle' function to you custom.
Manipulating Lua tables
Manipulating a Lua table can be done by reading a LuaTable
object. This can be achieved easily by reading a LuaTable
object.
let _:() = lua.exec_string("a = { 9, 8, 7 }").unwrap();
let mut table : LuaTable = lua.query("a").unwrap();
let x: i32 = table.query(2).unwrap();
assert_eq!(x, 8);
table.set(3, "hello");
let y: String = table.query(3).unwrap();
assert_eq!(y, "hello");
let z: i32 = table.query(1).unwrap();
assert_eq!(z, 9);
You can then iterate through the table with the .iter()
function. Note that the value returned by the iterator is an Option<(Key, Value)>
, the Option
being empty when either the key or the value is not convertible to the requested type. The filter_map
function (provided by the standard Iterator
trait) is very useful when dealing with this.
let _:() = lua.exec_string("a = { 9, 8, 7 }").unwrap();
let mut table : LuaTable = lua.query("a").unwrap();
for _ in 0 .. 10 {
let table_content: Vec<Option<(u32, u32)>> = table.iter().collect();
assert_eq!(table_content, vec![ Some((1,9)), Some((2,8)), Some((3,7)) ]);
}
User data
When you expose functions to Lua, you may wish to read or write more elaborate objects. This is called a user data.
To do so, you should implement the LuaPush
for your types.
This is usually done by redirecting the call to userdata::push_userdata
.
it will operate the ref of object
if you use userdata::push_userdata
the userdata will copy one time, for lua gc manager
if you use userdata::push_lightuserdata
the userdata life manager by rust, so none copy will occup
#[derive(Clone, Debug)]
struct Foo {
a : i32,
};
impl<'a> td_rlua::LuaPush for &'a mut Foo {
fn push_to_lua(self, lua: *mut c_lua::lua_State) -> i32 {
td_rlua::userdata::push_userdata(self, lua, |_|{})
}
}
impl<'a> td_rlua::LuaRead for &'a mut Foo {
fn lua_read_at_position(lua: *mut c_lua::lua_State, index: i32) -> Option<&'a mut Foo> {
td_rlua::userdata::read_userdata(lua, index)
}
}
let xx = &mut Foo {
a : 10,
};
lua.set("a", xx);
let get: &mut Foo = lua.query("a").unwrap();
assert!(get.a == 10);
get.a = 100;
let get: &mut Foo = lua.query("a").unwrap();
assert!(get.a == 100);
use lightuserdata you can change
impl<'a> td_rlua::LuaPush for &'a mut Foo {
fn push_to_lua(self, lua: *mut c_lua::lua_State) -> i32 {
td_rlua::userdata::push_lightuserdata(self, lua, |_|{})
}
}
custom lua call userdata need impl NewStruct
#[derive(Clone, Debug)]
struct TestLuaSturct {
index : i32,
}
impl NewStruct for TestLuaSturct {
fn new() -> TestLuaSturct {
println!("new !!!!!!!!!!!!!!");
TestLuaSturct {
index : 19,
}
}
fn name() -> &'static str {
"TestLuaSturct"
}
}
impl<'a> LuaRead for &'a mut TestLuaSturct {
fn lua_read_at_position(lua: *mut c_lua::lua_State, index: i32) -> Option<&'a mut TestLuaSturct> {
td_rlua::userdata::read_userdata(lua, index)
}
}
now we can custom function
let mut lua = Lua::new();
lua.openlibs();
fn one_arg(obj : &mut TestLuaSturct) -> i32 { obj.index = 10; 5 };
fn two_arg(obj : &mut TestLuaSturct, index : i32) { obj.index = index;};
let mut value = td_rlua::LuaStruct::<TestLuaSturct>::new(lua.state());
value.create().def("one_arg", td_rlua::function1(one_arg)).def("two_arg", td_rlua::function2(two_arg));
let _ : Option<()> = lua.exec_string("x = TestLuaSturct()");
let val : Option<i32> = lua.exec_string("return x:one_arg()");
assert_eq!(val, Some(5));
let obj : Option<&mut TestLuaSturct> = lua.query("x");
assert_eq!(obj.unwrap().index, 10);
let val : Option<i32> = lua.exec_string("x:two_arg(121)");
assert_eq!(val, None);
let obj : Option<&mut TestLuaSturct> = lua.query("x");
assert_eq!(obj.unwrap().index, 121);
let obj : Option<&mut TestLuaSturct> = lua.exec_string("return TestLuaSturct()");
assert_eq!(obj.unwrap().index, 19);
HotFix
in runtime, if we need change some logic, we need restart the process, it may lose some memory data so sometimes we need update the logic, add keep the memory data, so we need hotfix
let mut lua = Lua::new();
lua.openlibs();
lua.enable_hotfix();
let _ = lua.exec_func2("hotfix", r"
local value = {3, 4}
function get_a()
value[2] = 3
return value[1]
end
function get_b()
return value[2]
end
", "hotfix");
Refer
the project write refer to hlua, if you use lua5.2, you can use it.
Contributing
Contributions are welcome!