146 lines
4.9 KiB
Rust
146 lines
4.9 KiB
Rust
use std::os::raw::c_int;
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use crate::error::{Error, Result};
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use crate::ffi;
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use crate::types::LuaRef;
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use crate::util::{
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assert_stack, check_stack, error_traceback, pop_error, protect_lua_closure, StackGuard,
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};
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use crate::value::{FromLuaMulti, MultiValue, ToLuaMulti};
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/// Status of a Lua thread (or coroutine).
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#[derive(Debug, Copy, Clone, Eq, PartialEq)]
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pub enum ThreadStatus {
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/// The thread was just created, or is suspended because it has called `coroutine.yield`.
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///
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/// If a thread is in this state, it can be resumed by calling [`Thread::resume`].
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///
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/// [`Thread::resume`]: struct.Thread.html#method.resume
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Resumable,
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/// Either the thread has finished executing, or the thread is currently running.
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Unresumable,
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/// The thread has raised a Lua error during execution.
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Error,
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}
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/// Handle to an internal Lua thread (or coroutine).
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#[derive(Clone, Debug)]
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pub struct Thread<'lua>(pub(crate) LuaRef<'lua>);
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impl<'lua> Thread<'lua> {
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/// Resumes execution of this thread.
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///
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/// Equivalent to `coroutine.resume`.
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///
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/// Passes `args` as arguments to the thread. If the coroutine has called `coroutine.yield`, it
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/// will return these arguments. Otherwise, the coroutine wasn't yet started, so the arguments
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/// are passed to its main function.
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///
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/// If the thread is no longer in `Active` state (meaning it has finished execution or
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/// encountered an error), this will return `Err(CoroutineInactive)`, otherwise will return `Ok`
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/// as follows:
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///
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/// If the thread calls `coroutine.yield`, returns the values passed to `yield`. If the thread
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/// `return`s values from its main function, returns those.
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///
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/// # Examples
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///
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/// ```
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/// # use mlua::{Error, Lua, Result, Thread};
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/// # fn main() -> Result<()> {
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/// # let lua = Lua::new();
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/// let thread: Thread = lua.load(r#"
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/// coroutine.create(function(arg)
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/// assert(arg == 42)
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/// local yieldarg = coroutine.yield(123)
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/// assert(yieldarg == 43)
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/// return 987
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/// end)
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/// "#).eval()?;
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///
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/// assert_eq!(thread.resume::<_, u32>(42)?, 123);
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/// assert_eq!(thread.resume::<_, u32>(43)?, 987);
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///
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/// // The coroutine has now returned, so `resume` will fail
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/// match thread.resume::<_, u32>(()) {
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/// Err(Error::CoroutineInactive) => {},
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/// unexpected => panic!("unexpected result {:?}", unexpected),
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/// }
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/// # Ok(())
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/// # }
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/// ```
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pub fn resume<A, R>(&self, args: A) -> Result<R>
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where
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A: ToLuaMulti<'lua>,
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R: FromLuaMulti<'lua>,
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{
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let lua = self.0.lua;
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let args = args.to_lua_multi(lua)?;
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let results = unsafe {
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let _sg = StackGuard::new(lua.state);
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assert_stack(lua.state, 3);
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lua.push_ref(&self.0);
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let thread_state = ffi::lua_tothread(lua.state, -1);
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let status = ffi::lua_status(thread_state);
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if status != ffi::LUA_YIELD && ffi::lua_gettop(thread_state) == 0 {
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return Err(Error::CoroutineInactive);
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}
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ffi::lua_pop(lua.state, 1);
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let nargs = args.len() as c_int;
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check_stack(lua.state, nargs)?;
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check_stack(thread_state, nargs + 1)?;
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for arg in args {
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lua.push_value(arg)?;
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}
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ffi::lua_xmove(lua.state, thread_state, nargs);
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let ret = ffi::lua_resume(thread_state, lua.state, nargs);
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if ret != ffi::LUA_OK && ret != ffi::LUA_YIELD {
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protect_lua_closure(lua.state, 0, 0, |_| {
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error_traceback(thread_state);
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0
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})?;
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return Err(pop_error(thread_state, ret));
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}
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let nresults = ffi::lua_gettop(thread_state);
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let mut results = MultiValue::new();
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ffi::lua_xmove(thread_state, lua.state, nresults);
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assert_stack(lua.state, 2);
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for _ in 0..nresults {
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results.push_front(lua.pop_value());
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}
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results
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};
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R::from_lua_multi(results, lua)
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}
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/// Gets the status of the thread.
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pub fn status(&self) -> ThreadStatus {
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let lua = self.0.lua;
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unsafe {
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let _sg = StackGuard::new(lua.state);
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assert_stack(lua.state, 1);
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lua.push_ref(&self.0);
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let thread_state = ffi::lua_tothread(lua.state, -1);
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ffi::lua_pop(lua.state, 1);
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let status = ffi::lua_status(thread_state);
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if status != ffi::LUA_OK && status != ffi::LUA_YIELD {
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ThreadStatus::Error
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} else if status == ffi::LUA_YIELD || ffi::lua_gettop(thread_state) > 0 {
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ThreadStatus::Resumable
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} else {
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ThreadStatus::Unresumable
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}
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}
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}
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}
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