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//! High-level zero-cost bindings for Lua //! //! Lua is an interpreted programming language. This crate allows you to execute Lua code. //! //! # General usage //! //! In order to execute Lua code you first need a *Lua context*, which is represented in this //! library with [the `Lua` struct](struct.Lua.html). You can then call //! [the `execute` method](struct.Lua.html#method.execute) on this object. //! //! For example: //! //! ``` //! use hlua::Lua; //! //! let mut lua = Lua::new(); //! lua.execute::<()>("a = 12 * 5").unwrap(); //! ``` //! //! This example puts the value `60` in the global variable `a`. The values of all global variables //! are stored within the `Lua` struct. If you execute multiple Lua scripts on the same context, //! each script will have access to the same global variables that were modified by the previous //! scripts. //! //! In order to do something actually useful with Lua, we will need to make Lua and Rust //! communicate with each other. This can be done in four ways: //! //! - You can use methods on the `Lua` struct to read or write the values of global variables with //! the [`get`](struct.Lua.html#method.get) and [`set`](struct.Lua.html#method.set) methods. For //! example you can write to a global variable with a Lua script then read it from Rust, or you //! can write to a global variable from Rust then read it from a Lua script. //! //! - The Lua script that you execute with the [`execute`](struct.Lua.html#method.execute) method //! can return a value. //! //! - You can set the value of a global variable to a Rust functions or closures, which can then be //! invoked with a Lua script. See [the `Function` struct](struct.Function.html) for more //! information. For example if you set the value of the global variable `foo` to a Rust //! function, you can then call it from Lua with `foo()`. //! //! - Similarly you can set the value of a global variable to a Lua function, then call it from //! Rust. The function call can return a value. //! //! Which method(s) you use depends on which API you wish to expose to your Lua scripts. //! //! # Pushing and loading values //! //! The interface between Rust and Lua involves two things: //! //! - Sending values from Rust to Lua, which is known as *pushing* the value. //! - Sending values from Lua to Rust, which is known as *loading* the value. //! //! Pushing (ie. sending from Rust to Lua) can be done with //! [the `set` method](struct.Lua.html#method.set): //! //! ``` //! # use hlua::Lua; //! # let mut lua = Lua::new(); //! lua.set("a", 50); //! ``` //! //! You can push values that implement [the `Push` trait](trait.Push.html) or //! [the `PushOne` trait](trait.PushOne.html) depending on the situation: //! //! - Integers, floating point numbers and booleans. //! - `String` and `&str`. //! - Any Rust function or closure whose parameters and loadable and whose return type is pushable. //! See the documentation of [the `Function` struct](struct.Function.html) for more information. //! - [The `AnyLuaValue` struct](struct.AnyLuaValue.html). This enumeration represents any possible //! value in Lua. //! - The [`LuaCode`](struct.LuaCode.html) and //! [`LuaCodeFromReader`](struct.LuaCodeFromReader.html) structs. Since pushing these structs can //! result in an error, you need to use [`checked_set`](struct.Lua.html#method.checked_set) //! instead of `set`. //! - `Vec`s and `HashMap`s whose content is pushable. //! - As a special case, `Result` can be pushed only as the return type of a Rust function or //! closure. If they contain an error, the Rust function call is considered to have failed. //! - As a special case, tuples can be pushed when they are the return type of a Rust function or //! closure. They implement `Push` but not `PushOne`. //! - TODO: userdata //! //! Loading (ie. sending from Lua to Rust) can be done with //! [the `get` method](struct.Lua.html#method.get): //! //! ```no_run //! # use hlua::Lua; //! # let mut lua = Lua::new(); //! let a: i32 = lua.get("a").unwrap(); //! ``` //! //! You can load values that implement [the `LuaRead` trait](trait.LuaRead.html): //! //! - Integers, floating point numbers and booleans. //! - `String` and [`StringInLua`](struct.StringInLua.html) (ie. the equivalent of `&str`). Loading //! the latter has no cost while loading a `String` performs an allocation. //! - Any function (Lua or Rust), with [the `LuaFunction` struct](struct.LuaFunction.html). This //! can then be used to execute the function. //! - [The `AnyLuaValue` struct](struct.AnyLuaValue.html). This enumeration represents any possible //! value in Lua. //! - [The `LuaTable` struct](struct.LuaTable.html). This struct represents a table in Lua, where //! keys and values can be of different types. The table can then be iterated and individual //! elements can be loaded or modified. //! - As a special case, tuples can be loaded when they are the return type of a Lua function or as //! the return type of [`execute`](struct.Lua.html#method.execute). //! - TODO: userdata //! extern crate lua52_sys as ffi; extern crate libc; use std::ffi::{CStr, CString}; use std::io::Read; use std::io::Error as IoError; use std::borrow::Borrow; use std::marker::PhantomData; use std::error::Error; use std::fmt; use std::convert::From; use std::io; pub use any::{AnyHashableLuaValue, AnyLuaString, AnyLuaValue}; pub use functions_write::{Function, InsideCallback}; pub use functions_write::{function0, function1, function2, function3, function4, function5}; pub use functions_write::{function6, function7, function8, function9, function10}; pub use lua_functions::LuaFunction; pub use lua_functions::LuaFunctionCallError; pub use lua_functions::{LuaCode, LuaCodeFromReader}; pub use lua_tables::LuaTable; pub use lua_tables::LuaTableIterator; pub use tuples::TuplePushError; pub use userdata::UserdataOnStack; pub use userdata::{push_userdata, read_userdata}; pub use values::StringInLua; mod any; mod functions_write; mod lua_functions; mod lua_tables; mod macros; mod rust_tables; mod userdata; mod values; mod tuples; /// Main object of the library. /// /// The lifetime parameter corresponds to the lifetime of the content of the Lua context. /// /// # About panic safety /// /// This type isn't panic safe. This means that if a panic happens while you were using the `Lua`, /// then it will probably stay in a corrupt state. Trying to use the `Lua` again will most likely /// result in another panic but shouldn't result in unsafety. pub struct Lua<'lua> { lua: LuaContext, must_be_closed: bool, marker: PhantomData<&'lua ()>, } /// RAII guard for a value pushed on the stack. /// /// You shouldn't have to manipulate this type directly unless you are fiddling with the /// library's internals. pub struct PushGuard<L> { lua: L, size: i32, raw_lua: LuaContext, } impl<'lua, L> PushGuard<L> where L: AsMutLua<'lua> { #[inline] fn assert_one_and_forget(self) -> i32 { assert_eq!(self.size, 1); self.forget() } /// Prevents the value from being poped when the `PushGuard` is destroyed, and returns the /// number of elements on the stack. #[inline] fn forget(mut self) -> i32 { let size = self.size; self.size = 0; size } /// Destroys the guard, popping the value. Returns the inner part, /// which returns access when using by-value capture. #[inline] pub fn into_inner(mut self) -> L { use std::{mem, ptr}; let mut res; unsafe { res = mem::uninitialized(); ptr::copy_nonoverlapping(&self.lua, &mut res, 1); if self.size != 0 { ffi::lua_pop(self.lua.as_mut_lua().0, self.size); } }; mem::forget(self); res } } /// Trait for objects that have access to a Lua context. When using a context returned by a /// `AsLua`, you are not allowed to modify the stack. // TODO: the lifetime should be an associated lifetime instead pub unsafe trait AsLua<'lua> { fn as_lua(&self) -> LuaContext; } /// Trait for objects that have access to a Lua context. You are allowed to modify the stack, but /// it must be in the same state as it was when you started. // TODO: the lifetime should be an associated lifetime instead pub unsafe trait AsMutLua<'lua>: AsLua<'lua> { /// Returns the raw Lua context. fn as_mut_lua(&mut self) -> LuaContext; } /// Opaque type that contains the raw Lua context. // TODO: probably no longer necessary #[derive(Copy, Clone)] pub struct LuaContext(*mut ffi::lua_State); unsafe impl Send for LuaContext {} unsafe impl<'a, 'lua> AsLua<'lua> for Lua<'lua> { #[inline] fn as_lua(&self) -> LuaContext { self.lua } } unsafe impl<'lua> AsMutLua<'lua> for Lua<'lua> { #[inline] fn as_mut_lua(&mut self) -> LuaContext { self.lua } } unsafe impl<'lua, L> AsLua<'lua> for PushGuard<L> where L: AsMutLua<'lua> { #[inline] fn as_lua(&self) -> LuaContext { self.lua.as_lua() } } unsafe impl<'lua, L> AsMutLua<'lua> for PushGuard<L> where L: AsMutLua<'lua> { #[inline] fn as_mut_lua(&mut self) -> LuaContext { self.lua.as_mut_lua() } } unsafe impl<'a, 'lua, L: ?Sized> AsLua<'lua> for &'a L where L: AsLua<'lua> { #[inline] fn as_lua(&self) -> LuaContext { (**self).as_lua() } } unsafe impl<'a, 'lua, L: ?Sized> AsLua<'lua> for &'a mut L where L: AsLua<'lua> { #[inline] fn as_lua(&self) -> LuaContext { (**self).as_lua() } } unsafe impl<'a, 'lua, L: ?Sized> AsMutLua<'lua> for &'a mut L where L: AsMutLua<'lua> { #[inline] fn as_mut_lua(&mut self) -> LuaContext { (**self).as_mut_lua() } } /// Types that can be given to a Lua context, for example with `lua.set()` or as a return value /// of a function. pub trait Push<L> { /// Error that can happen when pushing a value. type Err; /// Pushes the value on the top of the stack. /// /// Must return a guard representing the elements that have been pushed. /// /// You can implement this for any type you want by redirecting to call to /// another implementation (for example `5.push_to_lua`) or by calling /// `userdata::push_userdata`. fn push_to_lua(self, lua: L) -> Result<PushGuard<L>, (Self::Err, L)>; /// Same as `push_to_lua` but can only succeed and is only available if `Err` is `Void`. // TODO: when https://github.com/rust-lang/rust/issues/20041 is fixed, use `Self::Err == Void` #[inline] fn push_no_err<E>(self, lua: L) -> PushGuard<L> where Self: Sized, Self: Push<L, Err = E>, E: Into<Void>, { match self.push_to_lua(lua) { Ok(p) => p, Err(_) => unreachable!(), } } } /// Extension trait for `Push`. Guarantees that only one element will be pushed. /// /// This should be implemented on most types that implement `Push`, except for tuples. /// /// > **Note**: Implementing this trait on a type that pushes multiple elements will most likely /// > result in panics. // Note for the implementation: since this trait is not unsafe, it is mostly a hint. Functions can // require this trait if they only accept one pushed element, but they must also add a runtime // assertion to make sure that only one element was actually pushed. pub trait PushOne<L>: Push<L> {} /// Type that cannot be instantiated. /// /// Will be replaced with `!` eventually (https://github.com/rust-lang/rust/issues/35121). #[derive(Debug, Copy, Clone)] pub enum Void {} /// Types that can be obtained from a Lua context. /// /// Most types that implement `Push` also implement `LuaRead`, but this is not always the case /// (for example `&'static str` implements `Push` but not `LuaRead`). pub trait LuaRead<L>: Sized { /// Reads the data from Lua. #[inline] fn lua_read(lua: L) -> Result<Self, L> { LuaRead::lua_read_at_position(lua, -1) } /// Reads the data from Lua at a given position. fn lua_read_at_position(lua: L, index: i32) -> Result<Self, L>; } /// Error that can happen when executing Lua code. #[derive(Debug)] pub enum LuaError { /// There was a syntax error when parsing the Lua code. SyntaxError(String), /// There was an error during execution of the Lua code /// (for example not enough parameters for a function call). ExecutionError(String), /// There was an IoError while reading the source code to execute. ReadError(IoError), /// The call to `execute` has requested the wrong type of data. WrongType, } impl fmt::Display for LuaError { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { use LuaError::*; match *self { SyntaxError(ref s) => write!(f, "Syntax error: {}", s), ExecutionError(ref s) => write!(f, "Execution error: {}", s), ReadError(ref e) => write!(f, "Read error: {}", e), WrongType => write!(f, "Wrong type returned by Lua"), } } } impl Error for LuaError { fn description(&self) -> &str { use LuaError::*; match *self { SyntaxError(ref s) => &s, ExecutionError(ref s) => &s, ReadError(_) => "read error", WrongType => "wrong type returned by Lua", } } fn cause(&self) -> Option<&Error> { use LuaError::*; match *self { SyntaxError(_) => None, ExecutionError(_) => None, ReadError(ref e) => Some(e), WrongType => None, } } } impl From<io::Error> for LuaError { fn from(e: io::Error) -> Self { LuaError::ReadError(e) } } impl<'lua> Lua<'lua> { /// Builds a new empty Lua context. /// /// There are no global variables and the registry is totally empty. Even the functions from /// the standard library can't be used. /// /// If you want to use the Lua standard library in the scripts of this context, see /// [the openlibs method](#method.openlibs) /// /// # Example /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// ``` /// /// # Panic /// /// The function panics if the underlying call to `lua_newstate` fails /// (which indicates lack of memory). #[inline] pub fn new() -> Lua<'lua> { let lua = unsafe { ffi::lua_newstate(alloc, std::ptr::null_mut()) }; if lua.is_null() { panic!("lua_newstate failed"); } // this alloc function is required to create a lua state. extern "C" fn alloc(_ud: *mut libc::c_void, ptr: *mut libc::c_void, _osize: libc::size_t, nsize: libc::size_t) -> *mut libc::c_void { unsafe { if nsize == 0 { libc::free(ptr as *mut libc::c_void); std::ptr::null_mut() } else { libc::realloc(ptr, nsize) } } } // called whenever lua encounters an unexpected error. extern "C" fn panic(lua: *mut ffi::lua_State) -> libc::c_int { let err = unsafe { ffi::lua_tostring(lua, -1) }; let err = unsafe { CStr::from_ptr(err) }; let err = String::from_utf8(err.to_bytes().to_vec()).unwrap(); panic!("PANIC: unprotected error in call to Lua API ({})\n", err); } unsafe { ffi::lua_atpanic(lua, panic) }; Lua { lua: LuaContext(lua), must_be_closed: true, marker: PhantomData, } } /// Takes an existing `lua_State` and build a Lua object from it. /// /// If `close_at_the_end` is true, `lua_close` will be called on the `lua_State` in the /// destructor. #[inline] pub unsafe fn from_existing_state<T>(lua: *mut T, close_at_the_end: bool) -> Lua<'lua> { Lua { lua: std::mem::transmute(lua), must_be_closed: close_at_the_end, marker: PhantomData, } } /// Opens all standard Lua libraries. /// /// See the reference for the standard library here: /// https://www.lua.org/manual/5.2/manual.html#6 /// /// This is done by calling `luaL_openlibs`. /// /// # Example /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// lua.openlibs(); /// ``` #[inline] pub fn openlibs(&mut self) { unsafe { ffi::luaL_openlibs(self.lua.0) } } /// Opens base library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_base #[inline] pub fn open_base(&mut self) { unsafe { ffi::luaopen_base(self.lua.0) } } /// Opens bit32 library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_bit32 #[inline] pub fn open_bit32(&mut self) { unsafe { ffi::luaopen_bit32(self.lua.0) } } /// Opens coroutine library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_coroutine #[inline] pub fn open_coroutine(&mut self) { unsafe { ffi::luaopen_coroutine(self.lua.0) } } /// Opens debug library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_debug #[inline] pub fn open_debug(&mut self) { unsafe { ffi::luaopen_debug(self.lua.0) } } /// Opens io library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_io #[inline] pub fn open_io(&mut self) { unsafe { ffi::luaopen_io(self.lua.0) } } /// Opens math library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_math #[inline] pub fn open_math(&mut self) { unsafe { ffi::luaopen_math(self.lua.0) } } /// Opens os library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_os #[inline] pub fn open_os(&mut self) { unsafe { ffi::luaopen_os(self.lua.0) } } /// Opens package library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_package #[inline] pub fn open_package(&mut self) { unsafe { ffi::luaopen_package(self.lua.0) } } /// Opens string library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_string #[inline] pub fn open_string(&mut self) { unsafe { ffi::luaopen_string(self.lua.0) } } /// Opens table library. /// /// https://www.lua.org/manual/5.2/manual.html#pdf-luaopen_table #[inline] pub fn open_table(&mut self) { unsafe { ffi::luaopen_table(self.lua.0) } } /// Executes some Lua code in the context. /// /// The code will have access to all the global variables you set with methods such as `set`. /// Every time you execute some code in the context, the code can modify these global variables. /// /// The template parameter of this function is the return type of the expression that is being /// evaluated. /// In order to avoid compilation error, you should call this function either by doing /// `lua.execute::<T>(...)` or `let result: T = lua.execute(...);` where `T` is the type of /// the expression. /// The function will return an error if the actual return type of the expression doesn't /// match the template parameter. /// /// The return type must implement the `LuaRead` trait. See /// [the documentation at the crate root](index.html#pushing-and-loading-values) for more /// information. /// /// # Examples /// /// Without a return value: /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// lua.execute::<()>("function multiply_by_two(a) return a * 2 end").unwrap(); /// lua.execute::<()>("twelve = multiply_by_two(6)").unwrap(); /// ``` /// /// With a return value: /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// /// let twelve: i32 = lua.execute("return 3 * 4;").unwrap(); /// let sixty = lua.execute::<i32>("return 6 * 10;").unwrap(); /// ``` #[inline] pub fn execute<'a, T>(&'a mut self, code: &str) -> Result<T, LuaError> where T: for<'g> LuaRead<PushGuard<&'g mut PushGuard<&'a mut Lua<'lua>>>> { let mut f = try!(lua_functions::LuaFunction::load(self, code)); f.call() } /// Executes some Lua code on the context. /// /// This does the same thing as [the `execute` method](#method.execute), but the code to /// execute is loaded from an object that implements `Read`. /// /// Use this method when you potentially have a large amount of code (for example if you read /// the code from a file) in order to avoid having to put everything in memory first before /// passing it to the Lua interpreter. /// /// # Example /// /// ```no_run /// use std::fs::File; /// use hlua::Lua; /// /// let mut lua = Lua::new(); /// let script = File::open("script.lua").unwrap(); /// lua.execute_from_reader::<(), _>(script).unwrap(); /// ``` #[inline] pub fn execute_from_reader<'a, T, R>(&'a mut self, code: R) -> Result<T, LuaError> where T: for<'g> LuaRead<PushGuard<&'g mut PushGuard<&'a mut Lua<'lua>>>>, R: Read { let mut f = try!(lua_functions::LuaFunction::load_from_reader(self, code)); f.call() } /// Reads the value of a global variable. /// /// Returns `None` if the variable doesn't exist or has the wrong type. /// /// The type must implement the `LuaRead` trait. See /// [the documentation at the crate root](index.html#pushing-and-loading-values) for more /// information. /// /// # Example /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// lua.execute::<()>("a = 5").unwrap(); /// let a: i32 = lua.get("a").unwrap(); /// assert_eq!(a, 5); /// ``` #[inline] pub fn get<'l, V, I>(&'l mut self, index: I) -> Option<V> where I: Borrow<str>, V: LuaRead<PushGuard<&'l mut Lua<'lua>>> { let index = CString::new(index.borrow()).unwrap(); unsafe { ffi::lua_getglobal(self.lua.0, index.as_ptr()); } if unsafe { ffi::lua_isnil(self.as_lua().0, -1) } { let raw_lua = self.as_lua(); let _guard = PushGuard { lua: self, size: 1, raw_lua: raw_lua, }; return None; } let raw_lua = self.as_lua(); let guard = PushGuard { lua: self, size: 1, raw_lua: raw_lua, }; LuaRead::lua_read(guard).ok() } /// Reads the value of a global, capturing the context by value. #[inline] pub fn into_get<V, I>(self, index: I) -> Result<V, PushGuard<Self>> where I: Borrow<str>, V: LuaRead<PushGuard<Lua<'lua>>> { let index = CString::new(index.borrow()).unwrap(); unsafe { ffi::lua_getglobal(self.lua.0, index.as_ptr()); } let is_nil = unsafe { ffi::lua_isnil(self.as_lua().0, -1) }; let raw_lua = self.as_lua(); let guard = PushGuard { lua: self, size: 1, raw_lua: raw_lua, }; if is_nil { Err(guard) } else { LuaRead::lua_read(guard) } } /// Modifies the value of a global variable. /// /// If you want to write an array, you are encouraged to use /// [the `empty_array` method](#method.empty_array) instead. /// /// The type must implement the `PushOne` trait. See /// [the documentation at the crate root](index.html#pushing-and-loading-values) for more /// information. /// /// # Example /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// /// lua.set("a", 12); /// let six: i32 = lua.execute("return a / 2;").unwrap(); /// assert_eq!(six, 6); /// ``` #[inline] pub fn set<I, V, E>(&mut self, index: I, value: V) where I: Borrow<str>, for<'a> V: PushOne<&'a mut Lua<'lua>, Err = E>, E: Into<Void>, { match self.checked_set(index, value) { Ok(_) => (), Err(_) => unreachable!(), } } /// Modifies the value of a global variable. // TODO: docs #[inline] pub fn checked_set<I, V, E>(&mut self, index: I, value: V) -> Result<(), E> where I: Borrow<str>, for<'a> V: PushOne<&'a mut Lua<'lua>, Err = E> { unsafe { // TODO: can be simplified let mut me = self; ffi::lua_pushglobaltable(me.lua.0); match index.borrow().push_to_lua(&mut me) { Ok(pushed) => { debug_assert_eq!(pushed.size, 1); pushed.forget() } Err(_) => unreachable!(), }; match value.push_to_lua(&mut me) { Ok(pushed) => { assert_eq!(pushed.size, 1); pushed.forget() } Err((err, lua)) => { ffi::lua_pop(lua.lua.0, 2); return Err(err); } }; ffi::lua_settable(me.lua.0, -3); ffi::lua_pop(me.lua.0, 1); Ok(()) } } /// Sets the value of a global variable to an empty array, then loads it. /// /// This is the function you should use if you want to set the value of a global variable to /// an array. After calling it, you will obtain a `LuaTable` object which you can then fill /// with the elements of the array. /// /// # Example /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// lua.openlibs(); // Necessary for `ipairs`. /// /// { /// let mut array = lua.empty_array("my_values"); /// array.set(1, 10); // Don't forget that Lua arrays are indexed from 1. /// array.set(2, 15); /// array.set(3, 20); /// } /// /// let sum: i32 = lua.execute(r#" /// local sum = 0 /// for i, val in ipairs(my_values) do /// sum = sum + val /// end /// return sum /// "#).unwrap(); /// /// assert_eq!(sum, 45); /// ``` #[inline] pub fn empty_array<'a, I>(&'a mut self, index: I) -> LuaTable<PushGuard<&'a mut Lua<'lua>>> where I: Borrow<str> { unsafe { let mut me = self; ffi::lua_pushglobaltable(me.lua.0); match index.borrow().push_to_lua(&mut me) { Ok(pushed) => pushed.forget(), Err(_) => unreachable!(), }; ffi::lua_newtable(me.lua.0); ffi::lua_settable(me.lua.0, -3); ffi::lua_pop(me.lua.0, 1); // TODO: cleaner implementation me.get(index).unwrap() } } /// Loads the array containing the global variables. /// /// In lua, the global variables accessible from the lua code are all part of a table which /// you can load here. /// /// # Examples /// /// The function can be used to write global variables, just like `set`. /// /// ``` /// use hlua::Lua; /// let mut lua = Lua::new(); /// lua.globals_table().set("a", 5); /// assert_eq!(lua.get::<i32, _>("a"), Some(5)); /// ``` /// /// A more useful feature for this function is that it allows you to set the metatable of the /// global variables. See TODO for more info. /// /// ``` /// use hlua::Lua; /// use hlua::AnyLuaValue; /// /// let mut lua = Lua::new(); /// { /// let mut metatable = lua.globals_table().get_or_create_metatable(); /// metatable.set("__index", hlua::function2(|_: AnyLuaValue, var: String| -> AnyLuaValue { /// println!("The user tried to access the variable {:?}", var); /// AnyLuaValue::LuaNumber(48.0) /// })); /// } /// /// let b: i32 = lua.execute("return b * 2;").unwrap(); /// // -> The user tried to access the variable "b" /// /// assert_eq!(b, 96); /// ``` #[inline] pub fn globals_table<'a>(&'a mut self) -> LuaTable<PushGuard<&'a mut Lua<'lua>>> { unsafe { ffi::lua_pushglobaltable(self.lua.0); } let raw_lua = self.as_lua(); let guard = PushGuard { lua: self, size: 1, raw_lua: raw_lua, }; LuaRead::lua_read(guard).ok().unwrap() } } impl<'lua> Drop for Lua<'lua> { #[inline] fn drop(&mut self) { if self.must_be_closed { unsafe { ffi::lua_close(self.lua.0) } } } } impl<L> Drop for PushGuard<L> { #[inline] fn drop(&mut self) { if self.size != 0 { unsafe { ffi::lua_pop(self.raw_lua.0, self.size); } } } } #[cfg(test)] mod tests { use Lua; use LuaError; #[test] fn open_base_opens_base_library() { let mut lua = Lua::new(); match lua.execute::<()>("return assert(true)") { Err(LuaError::ExecutionError(_)) => { }, Err(_) => panic!("Wrong error"), Ok(_) => panic!("Unexpected success"), } lua.open_base(); let result: bool = lua.execute("return assert(true)").unwrap(); assert_eq!(result, true); } #[test] fn opening_all_libraries_doesnt_panic() { let mut lua = Lua::new(); lua.open_base(); lua.open_bit32(); lua.open_coroutine(); lua.open_debug(); lua.open_io(); lua.open_math(); lua.open_os(); lua.open_package(); lua.open_string(); lua.open_table(); } }