Struct Lua 

pub struct Lua { /* private fields */ }

Top level Lua struct which represents an instance of Lua VM.

Implementations

impl Lua

pub fn create_require_function<R: Require + MaybeSend + 'static>( &self, require: R, ) -> Result<Function>

Available on crate feature luau only.

Create a custom Luau require function using provided Require implementation to find and load modules.

impl Lua

pub fn new() -> Lua

Creates a new Lua state and loads the safe subset of the standard libraries.

Safety

The created Lua state will have some safety guarantees and will not allow to load unsafe standard libraries or C modules.

See StdLib documentation for a list of unsafe modules that cannot be loaded.

pub unsafe fn unsafe_new() -> Lua

Creates a new Lua state and loads all the standard libraries.

Safety

The created Lua state will not have safety guarantees and will allow to load C modules.

pub fn new_with(libs: StdLib, options: LuaOptions) -> Result<Lua>

Creates a new Lua state and loads the specified safe subset of the standard libraries.

Use the StdLib flags to specify the libraries you want to load.

Safety

The created Lua state will have some safety guarantees and will not allow to load unsafe standard libraries or C modules.

See StdLib documentation for a list of unsafe modules that cannot be loaded.

pub unsafe fn unsafe_new_with(libs: StdLib, options: LuaOptions) -> Lua

Creates a new Lua state and loads the specified subset of the standard libraries.

Use the StdLib flags to specify the libraries you want to load.

Safety

The created Lua state will not have safety guarantees and allow to load C modules.

pub unsafe fn get_or_init_from_ptr<'a>(state: *mut lua_State) -> &'a Lua

Returns or constructs Lua instance from a raw state.

Once initialized, the returned Lua instance is cached in the registry and can be retrieved by calling this function again.

Safety

The Lua must outlive the chosen lifetime 'a.

pub unsafe fn exec_raw<R: FromLuaMulti>( &self, args: impl IntoLuaMulti, f: impl FnOnce(*mut lua_State), ) -> Result<R>

Calls provided function passing a raw lua state.

The arguments will be pushed onto the stack before calling the function.

This method ensures that the Lua instance is locked while the function is called and restores Lua stack after the function returns.

Example

let lua = Lua::new();
let n: i32 = unsafe {
    let nums = (3, 4, 5);
    lua.exec_raw(nums, |state| {
        let n = ffi::lua_gettop(state);
        let mut sum = 0;
        for i in 1..=n {
            sum += ffi::lua_tointeger(state, i);
        }
        ffi::lua_pop(state, n);
        ffi::lua_pushinteger(state, sum);
    })
}?;
assert_eq!(n, 12);

pub fn load_std_libs(&self, libs: StdLib) -> Result<()>

Loads the specified subset of the standard libraries into an existing Lua state.

Use the StdLib flags to specify the libraries you want to load.

pub fn register_module(&self, modname: &str, value: impl IntoLua) -> Result<()>

Registers module into an existing Lua state using the specified value.

After registration, the given value will always be immediately returned when the given module is required.

pub fn preload_module(&self, modname: &str, func: Function) -> Result<()>

Available on non-crate feature luau only.

Preloads module into an existing Lua state using the specified loader function.

When the module is required, the loader function will be called with module name as the first argument.

This is similar to setting the [package.preload[modname]] field.

[package.preload[modname]]: https://www.lua.org/manual/5.4/manual.html#pdf-package.preload

pub fn unload_module(&self, modname: &str) -> Result<()>

Unloads module modname.

This method does not support unloading binary Lua modules since they are internally cached and can be unloaded only by closing Lua state.

This is similar to calling Lua::register_module with Nil value.

pub fn sandbox(&self, enabled: bool) -> Result<()>

Available on crate feature luau only.

Enables (or disables) sandbox mode on this Lua instance.

This method, in particular:

• Set all libraries to read-only
• Set all builtin metatables to read-only
• Set globals to read-only (and activates safeenv)
• Setup local environment table that performs writes locally and proxies reads to the global environment.
• Allow only count mode in collectgarbage function.

Examples

let lua = Lua::new();

lua.sandbox(true)?;
lua.load("var = 123").exec()?;
assert_eq!(lua.globals().get::<u32>("var")?, 123);

// Restore the global environment (clear changes made in sandbox)
lua.sandbox(false)?;
assert_eq!(lua.globals().get::<Option<u32>>("var")?, None);

pub fn set_global_hook<F>( &self, triggers: HookTriggers, callback: F, ) -> Result<()>

where F: Fn(&Lua, &Debug<'_>) -> Result<VmState> + MaybeSend + 'static,

Available on non-crate feature luau only.

Sets or replaces a global hook function that will periodically be called as Lua code executes.

All new threads created (by mlua) after this call will use the global hook function.

For more information see Lua::set_hook.

pub fn set_hook<F>(&self, triggers: HookTriggers, callback: F) -> Result<()>

where F: Fn(&Lua, &Debug<'_>) -> Result<VmState> + MaybeSend + 'static,

Available on non-crate feature luau only.

Sets a hook function that will periodically be called as Lua code executes.

When exactly the hook function is called depends on the contents of the triggers parameter, see HookTriggers for more details.

The provided hook function can error, and this error will be propagated through the Lua code that was executing at the time the hook was triggered. This can be used to implement a limited form of execution limits by setting HookTriggers.every_nth_instruction and erroring once an instruction limit has been reached.

This method sets a hook function for the current thread of this Lua instance. If you want to set a hook function for another thread (coroutine), use Thread::set_hook instead.

Example

Shows each line number of code being executed by the Lua interpreter.

let lua = Lua::new();
lua.set_hook(HookTriggers::EVERY_LINE, |_lua, debug| {
    println!("line {:?}", debug.current_line());
    Ok(VmState::Continue)
});

lua.load(r#"
    local x = 2 + 3
    local y = x * 63
    local z = string.len(x..", "..y)
"#).exec()

pub fn remove_global_hook(&self)

Available on non-crate feature luau only.

Removes a global hook previously set by Lua::set_global_hook.

This function has no effect if a hook was not previously set.

pub fn remove_hook(&self)

Available on non-crate feature luau only.

Removes any hook from the current thread.

This function has no effect if a hook was not previously set.

pub fn set_interrupt<F>(&self, callback: F)

where F: Fn(&Lua) -> Result<VmState> + MaybeSend + 'static,

Available on crate feature luau only.

Sets an interrupt function that will periodically be called by Luau VM.

Any Luau code is guaranteed to call this handler “eventually” (in practice this can happen at any function call or at any loop iteration). This is similar to Lua::set_hook but in more simplified form.

The provided interrupt function can error, and this error will be propagated through the Luau code that was executing at the time the interrupt was triggered. Also this can be used to implement continuous execution limits by instructing Luau VM to yield by returning VmState::Yield. The yield will happen only at yieldable points of execution (not across metamethod/C-call boundaries).

Example

Periodically yield Luau VM to suspend execution.

let lua = Lua::new();
let count = Arc::new(AtomicU64::new(0));
lua.set_interrupt(move |_| {
    if count.fetch_add(1, Ordering::Relaxed) % 2 == 0 {
        return Ok(VmState::Yield);
    }
    Ok(VmState::Continue)
});

let co = lua.create_thread(
    lua.load(r#"
        local b = 0
        for _, x in ipairs({1, 2, 3}) do b += x end
    "#)
    .into_function()?,
)?;
while co.status() == ThreadStatus::Resumable {
    co.resume::<()>(())?;
}

pub fn remove_interrupt(&self)

Available on crate feature luau only.

Removes any interrupt function previously set by set_interrupt.

This function has no effect if an ‘interrupt’ was not previously set.

pub fn set_thread_creation_callback<F>(&self, callback: F)

where F: Fn(&Lua, Thread) -> Result<()> + MaybeSend + 'static,

Available on crate feature luau only.

Sets a thread creation callback that will be called when a thread is created.

pub fn set_thread_collection_callback<F>(&self, callback: F)

where F: Fn(LightUserData) + MaybeSend + 'static,

Available on crate feature luau only.

Sets a thread collection callback that will be called when a thread is destroyed.

Luau GC does not support exceptions during collection, so the callback must be non-panicking. If the callback panics, the program will be aborted.

pub fn remove_thread_callbacks(&self)

Available on crate feature luau only.

Removes any thread creation or collection callbacks previously set by Lua::set_thread_creation_callback or Lua::set_thread_collection_callback.

This function has no effect if a thread callbacks were not previously set.

pub fn set_warning_function<F>(&self, callback: F)

where F: Fn(&Lua, &str, bool) -> Result<()> + MaybeSend + 'static,

Available on crate feature lua54 only.

Sets the warning function to be used by Lua to emit warnings.

pub fn remove_warning_function(&self)

Available on crate feature lua54 only.

Removes warning function previously set by set_warning_function.

This function has no effect if a warning function was not previously set.

pub fn warning(&self, msg: impl AsRef<str>, incomplete: bool)

Available on crate feature lua54 only.

Emits a warning with the given message.

A message in a call with incomplete set to true should be continued in another call to this function.

pub fn inspect_stack<R>( &self, level: usize, f: impl FnOnce(&Debug<'_>) -> R, ) -> Option<R>

Gets information about the interpreter runtime stack at a given level.

This function calls callback f, passing the [Debug] structure that can be used to get information about the function executing at a given level. Level 0 is the current running function, whereas level n+1 is the function that has called level n (except for tail calls, which do not count in the stack).

pub fn used_memory(&self) -> usize

Returns the amount of memory (in bytes) currently used inside this Lua state.

pub fn set_memory_limit(&self, limit: usize) -> Result<usize>

Sets a memory limit (in bytes) on this Lua state.

Once an allocation occurs that would pass this memory limit, a Error::MemoryError is generated instead. Returns previous limit (zero means no limit).

Does not work in module mode where Lua state is managed externally.

pub fn gc_is_running(&self) -> bool

Available on crate features lua54 or lua53 or lua52 or luau only.

Returns true if the garbage collector is currently running automatically.

pub fn gc_stop(&self)

Stop the Lua GC from running

pub fn gc_restart(&self)

Restarts the Lua GC if it is not running

pub fn gc_collect(&self) -> Result<()>

Perform a full garbage-collection cycle.

It may be necessary to call this function twice to collect all currently unreachable objects. Once to finish the current gc cycle, and once to start and finish the next cycle.

pub fn gc_step(&self) -> Result<bool>

Steps the garbage collector one indivisible step.

Returns true if this has finished a collection cycle.

pub fn gc_step_kbytes(&self, kbytes: c_int) -> Result<bool>

Steps the garbage collector as though memory had been allocated.

if kbytes is 0, then this is the same as calling gc_step. Returns true if this step has finished a collection cycle.

pub fn gc_set_pause(&self, pause: c_int) -> c_int

Sets the pause value of the collector.

Returns the previous value of pause. More information can be found in the Lua documentation.

For Luau this parameter sets GC goal

pub fn gc_set_step_multiplier(&self, step_multiplier: c_int) -> c_int

Sets the step multiplier value of the collector.

Returns the previous value of the step multiplier. More information can be found in the Lua documentation.

pub fn gc_inc( &self, pause: c_int, step_multiplier: c_int, step_size: c_int, ) -> GCMode

Changes the collector to incremental mode with the given parameters.

Returns the previous mode (always GCMode::Incremental in Lua < 5.4). More information can be found in the Lua documentation.

pub fn gc_gen(&self, minor_multiplier: c_int, major_multiplier: c_int) -> GCMode

Available on crate feature lua54 only.

Changes the collector to generational mode with the given parameters.

Returns the previous mode. More information about the generational GC can be found in the Lua 5.4 documentation.

pub fn set_compiler(&self, compiler: Compiler)

Available on crate feature luau only.

Sets a default Luau compiler (with custom options).

This compiler will be used by default to load all Lua chunks including via require function.

See Compiler for details and possible options.

pub fn enable_jit(&self, enable: bool)

Available on crate feature luau-jit only.

Toggles JIT compilation mode for new chunks of code.

By default JIT is enabled. Changing this option does not have any effect on already loaded functions.

pub fn load<'a>(&self, chunk: impl AsChunk + 'a) -> Chunk<'a>

Returns Lua source code as a Chunk builder type.

In order to actually compile or run the resulting code, you must call Chunk::exec or similar on the returned builder. Code is not even parsed until one of these methods is called.

pub fn create_string(&self, s: impl AsRef<[u8]>) -> Result<String>

Creates and returns an interned Lua string.

Lua strings can be arbitrary [u8] data including embedded nulls, so in addition to &str and &String, you can also pass plain &[u8] here.

pub fn create_buffer(&self, data: impl AsRef<[u8]>) -> Result<Buffer>

Available on crate feature luau only.

Creates and returns a Luau buffer object from a byte slice of data.

pub fn create_buffer_with_capacity(&self, size: usize) -> Result<Buffer>

Available on crate feature luau only.

Creates and returns a Luau buffer object with the specified size.

Size limit is 1GB. All bytes will be initialized to zero.

pub fn create_table(&self) -> Result<Table>

Creates and returns a new empty table.

pub fn create_table_with_capacity( &self, narr: usize, nrec: usize, ) -> Result<Table>

Creates and returns a new empty table, with the specified capacity.

• narr is a hint for how many elements the table will have as a sequence.
• nrec is a hint for how many other elements the table will have.

Lua may use these hints to preallocate memory for the new table.

pub fn create_table_from<K, V>( &self, iter: impl IntoIterator<Item = (K, V)>, ) -> Result<Table>

where K: IntoLua, V: IntoLua,

Creates a table and fills it with values from an iterator.

pub fn create_sequence_from<T>( &self, iter: impl IntoIterator<Item = T>, ) -> Result<Table>

where T: IntoLua,

Creates a table from an iterator of values, using 1.. as the keys.

pub fn create_function<F, A, R>(&self, func: F) -> Result<Function>

where F: Fn(&Lua, A) -> Result<R> + MaybeSend + 'static, A: FromLuaMulti, R: IntoLuaMulti,

Wraps a Rust function or closure, creating a callable Lua function handle to it.

The function’s return value is always a Result: If the function returns Err, the error is raised as a Lua error, which can be caught using (x)pcall or bubble up to the Rust code that invoked the Lua code. This allows using the ? operator to propagate errors through intermediate Lua code.

If the function returns Ok, the contained value will be converted to one or more Lua values. For details on Rust-to-Lua conversions, refer to the IntoLua and IntoLuaMulti traits.

Examples

Create a function which prints its argument:

let greet = lua.create_function(|_, name: String| {
    println!("Hello, {}!", name);
    Ok(())
});

Use tuples to accept multiple arguments:

let print_person = lua.create_function(|_, (name, age): (String, u8)| {
    println!("{} is {} years old!", name, age);
    Ok(())
});

pub fn create_function_mut<F, A, R>(&self, func: F) -> Result<Function>

where F: FnMut(&Lua, A) -> Result<R> + MaybeSend + 'static, A: FromLuaMulti, R: IntoLuaMulti,

Wraps a Rust mutable closure, creating a callable Lua function handle to it.

This is a version of Lua::create_function that accepts a FnMut argument.

pub unsafe fn create_c_function(&self, func: lua_CFunction) -> Result<Function>

Wraps a C function, creating a callable Lua function handle to it.

Safety

This function is unsafe because provides a way to execute unsafe C function.

pub fn create_async_function<F, A, FR, R>(&self, func: F) -> Result<Function>

where F: Fn(Lua, A) -> FR + MaybeSend + 'static, A: FromLuaMulti, FR: Future<Output = Result<R>> + MaybeSend + 'static, R: IntoLuaMulti,

Available on crate feature async only.

Wraps a Rust async function or closure, creating a callable Lua function handle to it.

While executing the function Rust will poll the Future and if the result is not ready, call yield() passing internal representation of a Poll::Pending value.

The function must be called inside Lua coroutine (Thread) to be able to suspend its execution. An executor should be used to poll AsyncThread and mlua will take a provided Waker in that case. Otherwise noop waker will be used if try to call the function outside of Rust executors.

The family of call_async() functions takes care about creating Thread.

Examples

Non blocking sleep:

use std::time::Duration;
use mlua::{Lua, Result};

async fn sleep(_lua: Lua, n: u64) -> Result<&'static str> {
    tokio::time::sleep(Duration::from_millis(n)).await;
    Ok("done")
}

#[tokio::main]
async fn main() -> Result<()> {
    let lua = Lua::new();
    lua.globals().set("sleep", lua.create_async_function(sleep)?)?;
    let res: String = lua.load("return sleep(...)").call_async(100).await?; // Sleep 100ms
    assert_eq!(res, "done");
    Ok(())
}

pub fn create_thread(&self, func: Function) -> Result<Thread>

Wraps a Lua function into a new thread (or coroutine).

Equivalent to coroutine.create.

pub fn create_userdata<T>(&self, data: T) -> Result<AnyUserData>

where T: UserData + MaybeSend + 'static,

Creates a Lua userdata object from a custom userdata type.

All userdata instances of the same type T shares the same metatable.

pub fn create_ser_userdata<T>(&self, data: T) -> Result<AnyUserData>

where T: UserData + Serialize + MaybeSend + 'static,

Available on crate feature serde only.

Creates a Lua userdata object from a custom serializable userdata type.

pub fn create_any_userdata<T>(&self, data: T) -> Result<AnyUserData>

where T: MaybeSend + 'static,

Creates a Lua userdata object from a custom Rust type.

You can register the type using Lua::register_userdata_type to add fields or methods before calling this method. Otherwise, the userdata object will have an empty metatable.

All userdata instances of the same type T shares the same metatable.

pub fn create_ser_any_userdata<T>(&self, data: T) -> Result<AnyUserData>

where T: Serialize + MaybeSend + 'static,

Available on crate feature serde only.

Creates a Lua userdata object from a custom serializable Rust type.

See Lua::create_any_userdata for more details.

pub fn register_userdata_type<T: 'static>( &self, f: impl FnOnce(&mut UserDataRegistry<T>), ) -> Result<()>

Registers a custom Rust type in Lua to use in userdata objects.

This methods provides a way to add fields or methods to userdata objects of a type T.

pub fn create_proxy<T>(&self) -> Result<AnyUserData>

where T: UserData + 'static,

Create a Lua userdata “proxy” object from a custom userdata type.

Proxy object is an empty userdata object that has T metatable attached. The main purpose of this object is to provide access to static fields and functions without creating an instance of type T.

You can get or set uservalues on this object but you cannot borrow any Rust type.

Examples

struct MyUserData(i32);

impl UserData for MyUserData {
    fn add_fields<F: UserDataFields<Self>>(fields: &mut F) {
        fields.add_field_method_get("val", |_, this| Ok(this.0));
    }

    fn add_methods<M: UserDataMethods<Self>>(methods: &mut M) {
        methods.add_function("new", |_, value: i32| Ok(MyUserData(value)));
    }
}

lua.globals().set("MyUserData", lua.create_proxy::<MyUserData>()?)?;

lua.load("assert(MyUserData.new(321).val == 321)").exec()?;

pub fn set_type_metatable<T: LuaType>(&self, metatable: Option<Table>)

Sets the metatable for a Lua builtin type.

The metatable will be shared by all values of the given type.

Examples

Change metatable for Lua boolean type:

let mt = lua.create_table()?;
mt.set("__tostring", lua.create_function(|_, b: bool| Ok(if b { "2" } else { "0" }))?)?;
lua.set_type_metatable::<bool>(Some(mt));
lua.load("assert(tostring(true) == '2')").exec()?;

pub fn globals(&self) -> Table

Returns a handle to the global environment.

pub fn set_globals(&self, globals: Table) -> Result<()>

Sets the global environment.

This will replace the current global environment with the provided globals table.

For Lua 5.2+ the globals table is stored in the registry and shared between all threads. For Lua 5.1 and Luau the globals table is stored in each thread.

Please note that any existing Lua functions have cached global environment and will not see the changes made by this method. To update the environment for existing Lua functions, use Function::set_environment.

pub fn current_thread(&self) -> Thread

Returns a handle to the active Thread.

For calls to Lua this will be the main Lua thread, for parameters given to a callback, this will be whatever Lua thread called the callback.

pub fn scope<'env, R>( &self, f: impl for<'scope> FnOnce(&'scope Scope<'scope, 'env>) -> Result<R>, ) -> Result<R>

Calls the given function with a Scope parameter, giving the function the ability to create userdata and callbacks from Rust types that are !Send or non-'static.

The lifetime of any function or userdata created through Scope lasts only until the completion of this method call, on completion all such created values are automatically dropped and Lua references to them are invalidated. If a script accesses a value created through Scope outside of this method, a Lua error will result. Since we can ensure the lifetime of values created through Scope, and we know that Lua cannot be sent to another thread while Scope is live, it is safe to allow !Send data types and whose lifetimes only outlive the scope lifetime.

pub fn coerce_string(&self, v: Value) -> Result<Option<String>>

Attempts to coerce a Lua value into a String in a manner consistent with Lua’s internal behavior.

To succeed, the value must be a string (in which case this is a no-op), an integer, or a number.

pub fn coerce_integer(&self, v: Value) -> Result<Option<Integer>>

Attempts to coerce a Lua value into an integer in a manner consistent with Lua’s internal behavior.

To succeed, the value must be an integer, a floating point number that has an exact representation as an integer, or a string that can be converted to an integer. Refer to the Lua manual for details.

pub fn coerce_number(&self, v: Value) -> Result<Option<Number>>

Attempts to coerce a Lua value into a Number in a manner consistent with Lua’s internal behavior.

To succeed, the value must be a number or a string that can be converted to a number. Refer to the Lua manual for details.

pub fn pack(&self, t: impl IntoLua) -> Result<Value>

Converts a value that implements IntoLua into a Value instance.

pub fn unpack<T: FromLua>(&self, value: Value) -> Result<T>

Converts a Value instance into a value that implements FromLua.

pub fn convert<U: FromLua>(&self, value: impl IntoLua) -> Result<U>

Converts a value that implements IntoLua into a FromLua variant.

pub fn pack_multi(&self, t: impl IntoLuaMulti) -> Result<MultiValue>

Converts a value that implements IntoLuaMulti into a MultiValue instance.

pub fn unpack_multi<T: FromLuaMulti>(&self, value: MultiValue) -> Result<T>

Converts a MultiValue instance into a value that implements FromLuaMulti.

pub fn set_named_registry_value(&self, key: &str, t: impl IntoLua) -> Result<()>

Set a value in the Lua registry based on a string key.

This value will be available to Rust from all Lua instances which share the same main state.

pub fn named_registry_value<T>(&self, key: &str) -> Result<T>

where T: FromLua,

Get a value from the Lua registry based on a string key.

Any Lua instance which shares the underlying main state may call this method to get a value previously set by Lua::set_named_registry_value.

pub fn unset_named_registry_value(&self, key: &str) -> Result<()>

Removes a named value in the Lua registry.

Equivalent to calling Lua::set_named_registry_value with a value of Nil.

pub fn create_registry_value(&self, t: impl IntoLua) -> Result<RegistryKey>

Place a value in the Lua registry with an auto-generated key.

This value will be available to Rust from all Lua instances which share the same main state.

Be warned, garbage collection of values held inside the registry is not automatic, see RegistryKey for more details. However, dropped RegistryKeys automatically reused to store new values.

pub fn registry_value<T: FromLua>(&self, key: &RegistryKey) -> Result<T>

Get a value from the Lua registry by its RegistryKey

Any Lua instance which shares the underlying main state may call this method to get a value previously placed by Lua::create_registry_value.

pub fn remove_registry_value(&self, key: RegistryKey) -> Result<()>

Removes a value from the Lua registry.

You may call this function to manually remove a value placed in the registry with Lua::create_registry_value. In addition to manual RegistryKey removal, you can also call Lua::expire_registry_values to automatically remove values from the registry whose RegistryKeys have been dropped.

pub fn replace_registry_value( &self, key: &mut RegistryKey, t: impl IntoLua, ) -> Result<()>

Replaces a value in the Lua registry by its RegistryKey.

An identifier used in RegistryKey may possibly be changed to a new value.

See Lua::create_registry_value for more details.

pub fn owns_registry_value(&self, key: &RegistryKey) -> bool

Returns true if the given RegistryKey was created by a Lua which shares the underlying main state with this Lua instance.

Other than this, methods that accept a RegistryKey will return Error::MismatchedRegistryKey if passed a RegistryKey that was not created with a matching Lua state.

pub fn expire_registry_values(&self)

Remove any registry values whose RegistryKeys have all been dropped.

Unlike normal handle values, RegistryKeys do not automatically remove themselves on Drop, but you can call this method to remove any unreachable registry values not manually removed by Lua::remove_registry_value.

pub fn set_app_data<T: MaybeSend + 'static>(&self, data: T) -> Option<T>

Sets or replaces an application data object of type T.

Application data could be accessed at any time by using Lua::app_data_ref or Lua::app_data_mut methods where T is the data type.

Panics

Panics if the app data container is currently borrowed.

Examples

use mlua::{Lua, Result};

fn hello(lua: &Lua, _: ()) -> Result<()> {
    let mut s = lua.app_data_mut::<&str>().unwrap();
    assert_eq!(*s, "hello");
    *s = "world";
    Ok(())
}

fn main() -> Result<()> {
    let lua = Lua::new();
    lua.set_app_data("hello");
    lua.create_function(hello)?.call::<()>(())?;
    let s = lua.app_data_ref::<&str>().unwrap();
    assert_eq!(*s, "world");
    Ok(())
}

pub fn try_set_app_data<T: MaybeSend + 'static>( &self, data: T, ) -> StdResult<Option<T>, T>

Tries to set or replace an application data object of type T.

Returns:

• Ok(Some(old_data)) if the data object of type T was successfully replaced.
• Ok(None) if the data object of type T was successfully inserted.
• Err(data) if the data object of type T was not inserted because the container is currently borrowed.

See Lua::set_app_data for examples.

pub fn app_data_ref<T: 'static>(&self) -> Option<AppDataRef<'_, T>>

Gets a reference to an application data object stored by Lua::set_app_data of type T.

Panics

Panics if the data object of type T is currently mutably borrowed. Multiple immutable reads can be taken out at the same time.

pub fn try_app_data_ref<T: 'static>( &self, ) -> StdResult<Option<AppDataRef<'_, T>>, BorrowError>

Tries to get a reference to an application data object stored by Lua::set_app_data of type T.

pub fn app_data_mut<T: 'static>(&self) -> Option<AppDataRefMut<'_, T>>

Gets a mutable reference to an application data object stored by Lua::set_app_data of type T.

Panics

Panics if the data object of type T is currently borrowed.

pub fn try_app_data_mut<T: 'static>( &self, ) -> StdResult<Option<AppDataRefMut<'_, T>>, BorrowMutError>

Tries to get a mutable reference to an application data object stored by Lua::set_app_data of type T.

pub fn remove_app_data<T: 'static>(&self) -> Option<T>

Removes an application data of type T.

Panics

Panics if the app data container is currently borrowed.

pub async fn yield_with<R: FromLuaMulti>( &self, args: impl IntoLuaMulti, ) -> Result<R>

Available on crate feature async only.

Suspends the current async function, returning the provided arguments to caller.

This function is similar to coroutine.yield but allow yeilding Rust functions and passing values to the caller. Please note that you cannot cross Thread boundaries (e.g. calling yield_with on one thread and resuming on another).

Examples

Async iterator:

async fn generator(lua: Lua, _: ()) -> Result<()> {
    for i in 0..10 {
        lua.yield_with::<()>(i).await?;
    }
    Ok(())
}

fn main() -> Result<()> {
    let lua = Lua::new();
    lua.globals().set("generator", lua.create_async_function(generator)?)?;

    lua.load(r#"
       local n = 0
       for i in coroutine.wrap(generator) do
           n = n + i
       end
       assert(n == 45)
    "#)
    .exec()
}

Exchange values on yield:

async fn pingpong(lua: Lua, mut val: i32) -> Result<()> {
    loop {
        val = lua.yield_with::<i32>(val).await? + 1;
    }
    Ok(())
}

let lua = Lua::new();

let co = lua.create_thread(lua.create_async_function(pingpong)?)?;
assert_eq!(co.resume::<i32>(1)?, 1);
assert_eq!(co.resume::<i32>(2)?, 3);
assert_eq!(co.resume::<i32>(3)?, 4);

pub fn weak(&self) -> WeakLua

Returns a weak reference to the Lua instance.

This is useful for creating a reference to the Lua instance that does not prevent it from being deallocated.

Trait Implementations

impl Clone for Lua

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Lua

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Lua

fn default() -> Self

Returns the “default value” for a type.

impl Drop for Lua

fn drop(&mut self)

Executes the destructor for this type.

impl LuaSerdeExt for Lua

Available on crate feature serde only.

fn null(&self) -> Value

A special value (lightuserdata) to encode/decode optional (none) values.

fn array_metatable(&self) -> Table

A metatable attachable to a Lua table to systematically encode it as Array (instead of Map). As result, encoded Array will contain only sequence part of the table, with the same length as the # operator on that table.

fn to_value<T>(&self, t: &T) -> Result<Value>

where T: Serialize + ?Sized,

Converts T into a Value instance.

fn to_value_with<T>(&self, t: &T, options: Options) -> Result<Value>

where T: Serialize + ?Sized,

Converts T into a Value instance with options.

fn from_value<T>(&self, value: Value) -> Result<T>

where T: DeserializeOwned,

Deserializes a Value into any serde deserializable object.

fn from_value_with<T>(&self, value: Value, options: Options) -> Result<T>

where T: DeserializeOwned,

Deserializes a Value into any serde deserializable object with options.