482 lines
16 KiB
Rust
482 lines
16 KiB
Rust
use std::cell::{Ref, RefCell, RefMut};
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use std::marker::PhantomData;
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use std::collections::HashMap;
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use std::string::String as StdString;
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use ffi;
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use error::*;
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use util::*;
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use types::{Callback, LuaRef};
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use value::{FromLua, FromLuaMulti, ToLua, ToLuaMulti};
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use lua::Lua;
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/// Kinds of metamethods that can be overridden.
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///
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/// Currently, this mechanism does not allow overriding the `__gc` metamethod, since there is
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/// generally no need to do so: [`UserData`] implementors can instead just implement `Drop`.
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///
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/// [`UserData`]: trait.UserData.html
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#[derive(Debug, Copy, Clone, Eq, PartialEq, Hash)]
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pub enum MetaMethod {
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/// The `+` operator.
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Add,
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/// The `-` operator.
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Sub,
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/// The `*` operator.
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Mul,
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/// The `/` operator.
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Div,
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/// The `%` operator.
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Mod,
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/// The `^` operator.
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Pow,
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/// The unary minus (`-`) operator.
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Unm,
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/// The floor division (//) operator.
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IDiv,
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/// The bitwise AND (&) operator.
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BAnd,
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/// The bitwise OR (|) operator.
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BOr,
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/// The bitwise XOR (binary ~) operator.
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BXor,
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/// The bitwise NOT (unary ~) operator.
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BNot,
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/// The bitwise left shift (<<) operator.
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Shl,
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/// The bitwise right shift (>>) operator.
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Shr,
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/// The string concatenation operator `..`.
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Concat,
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/// The length operator `#`.
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Len,
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/// The `==` operator.
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Eq,
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/// The `<` operator.
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Lt,
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/// The `<=` operator.
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Le,
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/// Index access `obj[key]`.
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Index,
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/// Index write access `obj[key] = value`.
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NewIndex,
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/// The call "operator" `obj(arg1, args2, ...)`.
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Call,
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/// The `__tostring` metamethod.
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///
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/// This is not an operator, but will be called by methods such as `tostring` and `print`.
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ToString,
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}
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/// Method registry for [`UserData`] implementors.
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///
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/// [`UserData`]: trait.UserData.html
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pub struct UserDataMethods<'lua, T> {
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pub(crate) methods: HashMap<StdString, Callback<'lua, 'static>>,
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pub(crate) meta_methods: HashMap<MetaMethod, Callback<'lua, 'static>>,
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pub(crate) _type: PhantomData<T>,
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}
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impl<'lua, T: UserData> UserDataMethods<'lua, T> {
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/// Add a method which accepts a `&T` as the first parameter.
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///
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/// Regular methods are implemented by overriding the `__index` metamethod and returning the
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/// accessed method. This allows them to be used with the expected `userdata:method()` syntax.
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///
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/// If `add_meta_method` is used to override the `__index` metamethod, this approach will fall
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/// back to the user-provided metamethod if no regular method was found.
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pub fn add_method<A, R, M>(&mut self, name: &str, method: M)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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M: 'static + Send + for<'a> Fn(&'lua Lua, &'a T, A) -> Result<R>,
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{
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self.methods
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.insert(name.to_owned(), Self::box_method(method));
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}
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/// Add a regular method which accepts a `&mut T` as the first parameter.
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///
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/// Refer to [`add_method`] for more information about the implementation.
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///
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/// [`add_method`]: #method.add_method
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pub fn add_method_mut<A, R, M>(&mut self, name: &str, method: M)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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M: 'static + Send + for<'a> FnMut(&'lua Lua, &'a mut T, A) -> Result<R>,
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{
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self.methods
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.insert(name.to_owned(), Self::box_method_mut(method));
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}
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/// Add a regular method as a function which accepts generic arguments, the first argument will
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/// always be a `UserData` of type T.
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///
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/// Prefer to use [`add_method`] or [`add_method_mut`] as they are easier to use.
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///
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/// [`add_method`]: #method.add_method
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/// [`add_method_mut`]: #method.add_method_mut
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pub fn add_function<A, R, F>(&mut self, name: &str, function: F)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>,
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{
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self.methods
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.insert(name.to_owned(), Self::box_function(function));
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}
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/// Add a regular method as a mutable function which accepts generic arguments, the first
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/// argument will always be a `UserData` of type T.
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///
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/// This is a version of [`add_function`] that accepts a FnMut argument.
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///
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/// [`add_function`]: #method.add_function
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pub fn add_function_mut<A, R, F>(&mut self, name: &str, function: F)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>,
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{
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self.methods
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.insert(name.to_owned(), Self::box_function_mut(function));
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}
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/// Add a metamethod which accepts a `&T` as the first parameter.
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///
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/// # Note
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///
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/// This can cause an error with certain binary metamethods that can trigger if only the right
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/// side has a metatable. To prevent this, use [`add_meta_function`].
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///
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/// [`add_meta_function`]: #method.add_meta_function
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pub fn add_meta_method<A, R, M>(&mut self, meta: MetaMethod, method: M)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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M: 'static + Send + for<'a> Fn(&'lua Lua, &'a T, A) -> Result<R>,
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{
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self.meta_methods.insert(meta, Self::box_method(method));
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}
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/// Add a metamethod as a function which accepts a `&mut T` as the first parameter.
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///
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/// # Note
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///
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/// This can cause an error with certain binary metamethods that can trigger if only the right
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/// side has a metatable. To prevent this, use [`add_meta_function`].
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///
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/// [`add_meta_function`]: #method.add_meta_function
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pub fn add_meta_method_mut<A, R, M>(&mut self, meta: MetaMethod, method: M)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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M: 'static + Send + for<'a> FnMut(&'lua Lua, &'a mut T, A) -> Result<R>,
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{
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self.meta_methods.insert(meta, Self::box_method_mut(method));
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}
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/// Add a metamethod which accepts generic arguments.
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///
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/// Metamethods for binary operators can be triggered if either the left or right argument to
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/// the binary operator has a metatable, so the first argument here is not necessarily a
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/// userdata of type `T`.
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pub fn add_meta_function<A, R, F>(&mut self, meta: MetaMethod, function: F)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>,
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{
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self.meta_methods.insert(meta, Self::box_function(function));
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}
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/// Add a metamethod as a mutable function which accepts generic arguments.
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///
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/// This is a version of [`add_meta_function`] that accepts a FnMut argument.
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///
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/// [`add_meta_function`]: #method.add_meta_function
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pub fn add_meta_function_mut<A, R, F>(&mut self, meta: MetaMethod, function: F)
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>,
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{
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self.meta_methods
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.insert(meta, Self::box_function_mut(function));
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}
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fn box_function<A, R, F>(function: F) -> Callback<'lua, 'static>
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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F: 'static + Send + Fn(&'lua Lua, A) -> Result<R>,
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{
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Box::new(move |lua, args| function(lua, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua))
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}
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fn box_function_mut<A, R, F>(function: F) -> Callback<'lua, 'static>
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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F: 'static + Send + FnMut(&'lua Lua, A) -> Result<R>,
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{
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let function = RefCell::new(function);
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Box::new(move |lua, args| {
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let function = &mut *function
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.try_borrow_mut()
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.map_err(|_| Error::RecursiveMutCallback)?;
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function(lua, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
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})
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}
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fn box_method<A, R, M>(method: M) -> Callback<'lua, 'static>
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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M: 'static + Send + for<'a> Fn(&'lua Lua, &'a T, A) -> Result<R>,
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{
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Box::new(move |lua, mut args| {
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if let Some(front) = args.pop_front() {
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let userdata = AnyUserData::from_lua(front, lua)?;
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let userdata = userdata.borrow::<T>()?;
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method(lua, &userdata, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
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} else {
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Err(Error::FromLuaConversionError {
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from: "missing argument",
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to: "userdata",
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message: None,
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})
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}
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})
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}
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fn box_method_mut<A, R, M>(method: M) -> Callback<'lua, 'static>
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where
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A: FromLuaMulti<'lua>,
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R: ToLuaMulti<'lua>,
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M: 'static + Send + for<'a> FnMut(&'lua Lua, &'a mut T, A) -> Result<R>,
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{
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let method = RefCell::new(method);
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Box::new(move |lua, mut args| {
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if let Some(front) = args.pop_front() {
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let userdata = AnyUserData::from_lua(front, lua)?;
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let mut userdata = userdata.borrow_mut::<T>()?;
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let mut method = method
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.try_borrow_mut()
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.map_err(|_| Error::RecursiveMutCallback)?;
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(&mut *method)(lua, &mut userdata, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
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} else {
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Err(Error::FromLuaConversionError {
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from: "missing argument",
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to: "userdata",
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message: None,
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})
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}
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})
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}
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}
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/// Trait for custom userdata types.
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///
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/// By implementing this trait, a struct becomes eligible for use inside Lua code. Implementations
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/// of [`ToLua`] and [`FromLua`] are automatically provided.
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///
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/// # Examples
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///
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/// ```
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/// # extern crate rlua;
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/// # use rlua::{Lua, UserData, Result};
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/// # fn try_main() -> Result<()> {
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/// struct MyUserData(i32);
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///
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/// impl UserData for MyUserData {}
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///
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/// let lua = Lua::new();
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///
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/// // `MyUserData` now implements `ToLua`:
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/// lua.globals().set("myobject", MyUserData(123))?;
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///
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/// lua.exec::<()>("assert(type(myobject) == 'userdata')", None)?;
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/// # Ok(())
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/// # }
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/// # fn main() {
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/// # try_main().unwrap();
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/// # }
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/// ```
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///
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/// Custom methods and operators can be provided by implementing `add_methods` (refer to
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/// [`UserDataMethods`] for more information):
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///
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/// ```
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/// # extern crate rlua;
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/// # use rlua::{Lua, MetaMethod, UserData, UserDataMethods, Result};
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/// # fn try_main() -> Result<()> {
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/// struct MyUserData(i32);
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///
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/// impl UserData for MyUserData {
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/// fn add_methods(methods: &mut UserDataMethods<Self>) {
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/// methods.add_method("get", |_, this, _: ()| {
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/// Ok(this.0)
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/// });
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///
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/// methods.add_method_mut("add", |_, this, value: i32| {
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/// this.0 += value;
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/// Ok(())
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/// });
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///
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/// methods.add_meta_method(MetaMethod::Add, |_, this, value: i32| {
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/// Ok(this.0 + value)
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/// });
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/// }
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/// }
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///
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/// let lua = Lua::new();
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///
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/// lua.globals().set("myobject", MyUserData(123))?;
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///
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/// lua.exec::<()>(r#"
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/// assert(myobject:get() == 123)
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/// myobject:add(7)
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/// assert(myobject:get() == 130)
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/// assert(myobject + 10 == 140)
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/// "#, None)?;
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/// # Ok(())
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/// # }
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/// # fn main() {
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/// # try_main().unwrap();
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/// # }
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/// ```
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///
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/// [`ToLua`]: trait.ToLua.html
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/// [`FromLua`]: trait.FromLua.html
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/// [`UserDataMethods`]: struct.UserDataMethods.html
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pub trait UserData: 'static + Sized {
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/// Adds custom methods and operators specific to this userdata.
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fn add_methods(_methods: &mut UserDataMethods<Self>) {}
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}
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/// Handle to an internal Lua userdata for any type that implements [`UserData`].
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///
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/// Similar to `std::any::Any`, this provides an interface for dynamic type checking via the [`is`]
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/// and [`borrow`] methods.
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///
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/// Internally, instances are stored in a `RefCell`, to best match the mutable semantics of the Lua
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/// language.
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///
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/// # Note
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///
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/// This API should only be used when necessary. Implementing [`UserData`] already allows defining
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/// methods which check the type and acquire a borrow behind the scenes.
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///
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/// [`UserData`]: trait.UserData.html
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/// [`is`]: #method.is
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/// [`borrow`]: #method.borrow
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#[derive(Clone, Debug)]
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pub struct AnyUserData<'lua>(pub(crate) LuaRef<'lua>);
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impl<'lua> AnyUserData<'lua> {
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/// Checks whether the type of this userdata is `T`.
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pub fn is<T: UserData>(&self) -> Result<bool> {
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match self.inspect(|_: &RefCell<T>| Ok(())) {
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Ok(()) => Ok(true),
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Err(Error::UserDataTypeMismatch) => Ok(false),
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Err(err) => Err(err),
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}
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}
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/// Borrow this userdata immutably if it is of type `T`.
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///
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/// # Errors
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///
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/// Returns a `UserDataBorrowError` if the userdata is already mutably borrowed. Returns a
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/// `UserDataTypeMismatch` if the userdata is not of type `T`.
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pub fn borrow<T: UserData>(&self) -> Result<Ref<T>> {
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self.inspect(|cell| Ok(cell.try_borrow().map_err(|_| Error::UserDataBorrowError)?))
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}
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/// Borrow this userdata mutably if it is of type `T`.
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///
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/// # Errors
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///
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/// Returns a `UserDataBorrowMutError` if the userdata is already borrowed. Returns a
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/// `UserDataTypeMismatch` if the userdata is not of type `T`.
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pub fn borrow_mut<T: UserData>(&self) -> Result<RefMut<T>> {
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self.inspect(|cell| {
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Ok(cell.try_borrow_mut()
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.map_err(|_| Error::UserDataBorrowMutError)?)
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})
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}
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fn inspect<'a, T, R, F>(&'a self, func: F) -> Result<R>
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where
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T: UserData,
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F: FnOnce(&'a RefCell<T>) -> Result<R>,
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{
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unsafe {
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let lua = self.0.lua;
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stack_err_guard(lua.state, move || {
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check_stack(lua.state, 3);
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lua.push_ref(lua.state, &self.0);
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rlua_assert!(
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ffi::lua_getmetatable(lua.state, -1) != 0,
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"AnyUserData missing metatable"
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);
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ffi::lua_rawgeti(
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lua.state,
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ffi::LUA_REGISTRYINDEX,
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lua.userdata_metatable::<T>()? as ffi::lua_Integer,
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);
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if ffi::lua_rawequal(lua.state, -1, -2) == 0 {
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ffi::lua_pop(lua.state, 3);
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Err(Error::UserDataTypeMismatch)
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} else {
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let res = func(&*get_userdata::<RefCell<T>>(lua.state, -3));
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ffi::lua_pop(lua.state, 3);
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res
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}
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})
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}
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}
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/// Sets an associated value to this `AnyUserData`.
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///
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/// The value may be any Lua value whatsoever, and can be retrieved with [`get_user_value`].
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///
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/// [`get_user_value`]: #method.get_user_value
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pub fn set_user_value<V: ToLua<'lua>>(&self, v: V) -> Result<()> {
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let lua = self.0.lua;
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unsafe {
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stack_err_guard(lua.state, || {
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check_stack(lua.state, 2);
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lua.push_ref(lua.state, &self.0);
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lua.push_value(lua.state, v.to_lua(lua)?);
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ffi::lua_setuservalue(lua.state, -2);
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ffi::lua_pop(lua.state, 1);
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Ok(())
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})
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}
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}
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/// Returns an associated value set by [`set_user_value`].
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///
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/// [`set_user_value`]: #method.set_user_value
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pub fn get_user_value<V: FromLua<'lua>>(&self) -> Result<V> {
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let lua = self.0.lua;
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unsafe {
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stack_err_guard(lua.state, || {
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check_stack(lua.state, 3);
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lua.push_ref(lua.state, &self.0);
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ffi::lua_getuservalue(lua.state, -1);
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let res = V::from_lua(lua.pop_value(lua.state), lua)?;
|
|
ffi::lua_pop(lua.state, 1);
|
|
Ok(res)
|
|
})
|
|
}
|
|
}
|
|
}
|