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use std::os::raw::c_int;
use error::{Error, Result};
use ffi;
use types::LuaRef;
use util::{assert_stack, check_stack, error_traceback, pop_error, StackGuard};
use value::{FromLuaMulti, MultiValue, ToLuaMulti};
/// Status of a Lua thread (or coroutine).
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub enum ThreadStatus {
/// The thread was just created, or is suspended because it has called `coroutine.yield`.
///
/// If a thread is in this state, it can be resumed by calling [`Thread::resume`].
///
/// [`Thread::resume`]: struct.Thread.html#method.resume
Resumable,
/// Either the thread has finished executing, or the thread is currently running.
Unresumable,
/// The thread has raised a Lua error during execution.
Error,
}
/// Handle to an internal Lua thread (or coroutine).
#[derive(Clone, Debug)]
pub struct Thread<'lua>(pub(crate) LuaRef<'lua>);
impl<'lua> Thread<'lua> {
/// Resumes execution of this thread.
///
/// Equivalent to `coroutine.resume`.
///
/// Passes `args` as arguments to the thread. If the coroutine has called `coroutine.yield`, it
/// will return these arguments. Otherwise, the coroutine wasn't yet started, so the arguments
/// are passed to its main function.
///
/// If the thread is no longer in `Active` state (meaning it has finished execution or
/// encountered an error), this will return `Err(CoroutineInactive)`, otherwise will return `Ok`
/// as follows:
///
/// If the thread calls `coroutine.yield`, returns the values passed to `yield`. If the thread
/// `return`s values from its main function, returns those.
///
/// # Examples
///
/// ```
/// # extern crate rlua;
/// # use rlua::{Lua, Thread, Error, Result};
/// # fn try_main() -> Result<()> {
/// let lua = Lua::new();
/// let thread: Thread = lua.eval(r#"
/// coroutine.create(function(arg)
/// assert(arg == 42)
/// local yieldarg = coroutine.yield(123)
/// assert(yieldarg == 43)
/// return 987
/// end)
/// "#, None).unwrap();
///
/// assert_eq!(thread.resume::<_, u32>(42).unwrap(), 123);
/// assert_eq!(thread.resume::<_, u32>(43).unwrap(), 987);
///
/// // The coroutine has now returned, so `resume` will fail
/// match thread.resume::<_, u32>(()) {
/// Err(Error::CoroutineInactive) => {},
/// unexpected => panic!("unexpected result {:?}", unexpected),
/// }
/// # Ok(())
/// # }
/// # fn main() {
/// # try_main().unwrap();
/// # }
/// ```
pub fn resume<A, R>(&self, args: A) -> Result<R>
where
A: ToLuaMulti<'lua>,
R: FromLuaMulti<'lua>,
{
let lua = self.0.lua;
let args = args.to_lua_multi(lua)?;
let results = unsafe {
let _sg = StackGuard::new(lua.state);
assert_stack(lua.state, 1);
lua.push_ref(&self.0);
let thread_state = ffi::lua_tothread(lua.state, -1);
let status = ffi::lua_status(thread_state);
if status != ffi::LUA_YIELD && ffi::lua_gettop(thread_state) == 0 {
return Err(Error::CoroutineInactive);
}
ffi::lua_pop(lua.state, 1);
let nargs = args.len() as c_int;
check_stack(lua.state, nargs)?;
check_stack(thread_state, nargs + 1)?;
for arg in args {
lua.push_value(arg);
}
ffi::lua_xmove(lua.state, thread_state, nargs);
let ret = ffi::lua_resume(thread_state, lua.state, nargs);
if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
error_traceback(thread_state);
return Err(pop_error(thread_state, ret));
}
let nresults = ffi::lua_gettop(thread_state);
let mut results = MultiValue::new();
ffi::lua_xmove(thread_state, lua.state, nresults);
assert_stack(lua.state, 2);
for _ in 0..nresults {
results.push_front(lua.pop_value());
}
results
};
R::from_lua_multi(results, lua)
}
/// Gets the status of the thread.
pub fn status(&self) -> ThreadStatus {
let lua = self.0.lua;
unsafe {
let _sg = StackGuard::new(lua.state);
assert_stack(lua.state, 1);
lua.push_ref(&self.0);
let thread_state = ffi::lua_tothread(lua.state, -1);
ffi::lua_pop(lua.state, 1);
let status = ffi::lua_status(thread_state);
if status != ffi::LUA_OK && status != ffi::LUA_YIELD {
ThreadStatus::Error
} else if status == ffi::LUA_YIELD || ffi::lua_gettop(thread_state) > 0 {
ThreadStatus::Resumable
} else {
ThreadStatus::Unresumable
}
}
}
}