low_luajit/lua/type/
nil.rs

1use crate::{AmountReturned, LuaState, ffi};
2
3/// Nil (& none) related functions.
4impl LuaState {
5	/// Returns `true` if the value at the given acceptable `index` is `nil`, `false` otherwise.
6	#[inline]
7	#[must_use]
8	pub fn is_nil(&self, index: i32) -> bool {
9		// SAFETY: self.0 is always valid.
10		unsafe { ffi::lua_isnil(self.0, index) != 0 }
11	}
12
13	/// Returns `true` if the value at the given acceptable `index` is invalid (out of bounds), `false` otherwise.
14	#[inline]
15	#[must_use]
16	pub fn is_none(&self, index: i32) -> bool {
17		// SAFETY: self.0 is always valid.
18		unsafe { ffi::lua_isnone(self.0, index) != 0 }
19	}
20
21	/// Returns `true` if the value at the given acceptable `index` is `nil` or invalid (out of bounds), `false` otherwise.
22	#[inline]
23	#[must_use]
24	pub fn is_none_or_nil(&self, index: i32) -> bool {
25		// SAFETY: self.0 is always valid.
26		unsafe { ffi::lua_isnoneornil(self.0, index) != 0 }
27	}
28
29	/// Pushes `nil` onto the stack.
30	#[inline]
31	pub fn push_nil(&mut self) {
32		// SAFETY: self.0 is always valid.
33		unsafe { ffi::lua_pushnil(self.0); }
34	}
35
36	/// Finishes the currently called [`CFunction`], returning `nil` to the caller.
37	///
38	/// The `LuaState` wrapper is consumed to prevent invalidating the [`AmountReturned`] (the Lua state itself is left intact).
39	///
40	/// To return no value at all instead of `nil`, see [`LuaState::return_none`].
41	/// *(There is a small difference, but it's usually negligible.)*
42	///
43	/// [`CFunction`]: ./type.CFunction.html
44	#[inline]
45	pub fn return_nil(mut self) -> AmountReturned {
46		self.push_nil();
47
48		// SAFETY: There should always be at least one element in the stack.
49		unsafe { AmountReturned::unchecked(1) }
50	}
51
52	/// Finishes the currently called [`CFunction`], returning no value to the caller.
53	///
54	/// This is currently effectively the same as just returning [`AmountReturned::NONE`].
55	///
56	/// To return `nil` instead of no value at all, see [`LuaState::return_nil`].
57	/// *(There is a small difference, but it's usually negligible.)*
58	///
59	/// [`CFunction`]: ./type.CFunction.html
60	#[inline]
61	pub fn return_none(self) -> AmountReturned {
62		AmountReturned::NONE
63	}
64}
low_luajit/lua/type/nil.rs

low_luajit/lua/type/
nil.rs
