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use std::os::raw::c_int;
use ffi;
use error::*;
use util::*;
use types::LuaRef;
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;
unsafe {
stack_err_guard(lua.state, 0, || {
check_stack(lua.state, 1);
lua.push_ref(lua.state, &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 args = args.to_lua_multi(lua)?;
let nargs = args.len() as c_int;
check_stack(thread_state, nargs);
for arg in args {
lua.push_value(thread_state, arg);
}
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();
check_stack(thread_state, 1);
for _ in 0..nresults {
results.push_front(lua.pop_value(thread_state));
}
R::from_lua_multi(results, lua)
})
}
}
/// Gets the status of the thread.
pub fn status(&self) -> ThreadStatus {
let lua = self.0.lua;
unsafe {
stack_guard(lua.state, 0, || {
check_stack(lua.state, 1);
lua.push_ref(lua.state, &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
}
})
}
}
}
#[cfg(test)]
mod tests {
use std::panic::catch_unwind;
use super::{Thread, ThreadStatus};
use error::Error;
use function::Function;
use lua::Lua;
#[test]
fn test_thread() {
let lua = Lua::new();
let thread = lua.create_thread(lua.eval::<Function>(
r#"
function (s)
local sum = s
for i = 1,4 do
sum = sum + coroutine.yield(sum)
end
return sum
end
"#,
None,
).unwrap())
.unwrap();
assert_eq!(thread.status(), ThreadStatus::Resumable);
assert_eq!(thread.resume::<_, i64>(0).unwrap(), 0);
assert_eq!(thread.status(), ThreadStatus::Resumable);
assert_eq!(thread.resume::<_, i64>(1).unwrap(), 1);
assert_eq!(thread.status(), ThreadStatus::Resumable);
assert_eq!(thread.resume::<_, i64>(2).unwrap(), 3);
assert_eq!(thread.status(), ThreadStatus::Resumable);
assert_eq!(thread.resume::<_, i64>(3).unwrap(), 6);
assert_eq!(thread.status(), ThreadStatus::Resumable);
assert_eq!(thread.resume::<_, i64>(4).unwrap(), 10);
assert_eq!(thread.status(), ThreadStatus::Unresumable);
let accumulate = lua.create_thread(lua.eval::<Function>(
r#"
function (sum)
while true do
sum = sum + coroutine.yield(sum)
end
end
"#,
None,
).unwrap())
.unwrap();
for i in 0..4 {
accumulate.resume::<_, ()>(i).unwrap();
}
assert_eq!(accumulate.resume::<_, i64>(4).unwrap(), 10);
assert_eq!(accumulate.status(), ThreadStatus::Resumable);
assert!(accumulate.resume::<_, ()>("error").is_err());
assert_eq!(accumulate.status(), ThreadStatus::Error);
let thread = lua.eval::<Thread>(
r#"
coroutine.create(function ()
while true do
coroutine.yield(42)
end
end)
"#,
None,
).unwrap();
assert_eq!(thread.status(), ThreadStatus::Resumable);
assert_eq!(thread.resume::<_, i64>(()).unwrap(), 42);
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);
match thread.resume::<_, u32>(()) {
Err(Error::CoroutineInactive) => {}
Err(_) => panic!("resuming dead coroutine error is not CoroutineInactive kind"),
_ => panic!("resuming dead coroutine did not return error"),
}
}
#[test]
fn coroutine_from_closure() {
let lua = Lua::new();
let thrd_main = lua.create_function(|_, ()| Ok(())).unwrap();
lua.globals().set("main", thrd_main).unwrap();
let thrd: Thread = lua.eval("coroutine.create(main)", None).unwrap();
thrd.resume::<_, ()>(()).unwrap();
}
#[test]
fn coroutine_panic() {
// check that coroutines propagate panics correctly
let lua = Lua::new();
let thrd_main = lua.create_function(|lua, ()| {
// whoops, 'main' has a wrong type
let _coro: u32 = lua.globals().get("main").unwrap();
Ok(())
}).unwrap();
lua.globals().set("main", thrd_main.clone()).unwrap();
let thrd: Thread = lua.create_thread(thrd_main).unwrap();
match catch_unwind(|| thrd.resume::<_, ()>(())) {
Ok(r) => panic!("coroutine panic not propagated, instead returned {:?}", r),
Err(_) => {}
}
}
}