wit-bindgen 0.32.0

//! NB: These functions are not used any more by the latest version of the
//! bindings generator for Rust. These functions are provided for historical
//! compatibility with previous bindings generators before the 0.20.0 version
//! of wit-bindgen.
//!
//! Once `cargo component` has updated to `wit-bindgen` 0.20.0+ and has been
//! there for awhile this file should be removed.

extern crate alloc as alloc_crate;

use alloc_crate::alloc::Layout;
use alloc_crate::boxed::Box;
use alloc_crate::string::String;
use alloc_crate::vec::Vec;
use core::fmt;
use core::marker;
use core::ops::{Deref, DerefMut};
use core::sync::atomic::{AtomicU32, Ordering::Relaxed};

pub use alloc_crate::{alloc, boxed, string, vec};

pub unsafe fn dealloc(ptr: i32, size: usize, align: usize) {
    if size == 0 {
        return;
    }
    let layout = Layout::from_size_align_unchecked(size, align);
    alloc_crate::alloc::dealloc(ptr as *mut u8, layout);
}

macro_rules! as_traits {
	($(($trait_:ident $func:ident $ty:ident <=> $($tys:ident)*))*) => ($(
		pub fn $func<T: $trait_>(t: T) -> $ty {
			t.$func()
		}

		pub trait $trait_ {
			fn $func(self) -> $ty;
		}

		impl<'a, T: Copy + $trait_> $trait_ for &'a T {
			fn $func(self) -> $ty{
				(*self).$func()
			}
		}

		$(
			impl $trait_ for $tys {
				#[inline]
				fn $func(self) -> $ty {
					self as $ty
				}
			}
		)*

	)*)
}

as_traits! {
    (AsI64 as_i64 i64 <=> i64 u64)
    (AsI32 as_i32 i32 <=> i32 u32 i16 u16 i8 u8 char usize)
    (AsF32 as_f32 f32 <=> f32)
    (AsF64 as_f64 f64 <=> f64)
}

pub unsafe fn string_lift(bytes: Vec<u8>) -> String {
    if cfg!(debug_assertions) {
        String::from_utf8(bytes).unwrap()
    } else {
        String::from_utf8_unchecked(bytes)
    }
}

pub unsafe fn invalid_enum_discriminant<T>() -> T {
    if cfg!(debug_assertions) {
        panic!("invalid enum discriminant")
    } else {
        core::hint::unreachable_unchecked()
    }
}

pub unsafe fn char_lift(val: u32) -> char {
    if cfg!(debug_assertions) {
        core::char::from_u32(val).unwrap()
    } else {
        core::char::from_u32_unchecked(val)
    }
}

pub unsafe fn bool_lift(val: u8) -> bool {
    if cfg!(debug_assertions) {
        match val {
            0 => false,
            1 => true,
            _ => panic!("invalid bool discriminant"),
        }
    } else {
        core::mem::transmute::<u8, bool>(val)
    }
}

type RawRep<T> = Option<T>;

/// A type which represents a component model resource, either imported or
/// exported into this component.
///
/// This is a low-level wrapper which handles the lifetime of the resource
/// (namely this has a destructor). The `T` provided defines the component model
/// intrinsics that this wrapper uses.
///
/// One of the chief purposes of this type is to provide `Deref` implementations
/// to access the underlying data when it is owned.
///
/// This type is primarily used in generated code for exported and imported
/// resources.
#[repr(transparent)]
pub struct Resource<T: WasmResource> {
    // NB: This would ideally be `u32` but it is not. The fact that this has
    // interior mutability is not exposed in the API of this type except for the
    // `take_handle` method which is supposed to in theory be private.
    //
    // This represents, almost all the time, a valid handle value. When it's
    // invalid it's stored as `u32::MAX`.
    handle: AtomicU32,
    _marker: marker::PhantomData<Box<T>>,
}

/// A trait which all wasm resources implement, namely providing the ability to
/// drop a resource.
///
/// This generally is implemented by generated code, not user-facing code.
pub unsafe trait WasmResource {
    /// Invokes the `[resource-drop]...` intrinsic.
    unsafe fn drop(handle: u32);
}

/// A trait which extends [`WasmResource`] used for Rust-defined resources, or
/// those exported from this component.
///
/// This generally is implemented by generated code, not user-facing code.
pub unsafe trait RustResource: WasmResource {
    /// Invokes the `[resource-new]...` intrinsic.
    unsafe fn new(rep: usize) -> u32;
    /// Invokes the `[resource-rep]...` intrinsic.
    unsafe fn rep(handle: u32) -> usize;
}

impl<T: WasmResource> Resource<T> {
    #[doc(hidden)]
    pub unsafe fn from_handle(handle: u32) -> Self {
        debug_assert!(handle != u32::MAX);
        Self {
            handle: AtomicU32::new(handle),
            _marker: marker::PhantomData,
        }
    }

    /// Takes ownership of the handle owned by `resource`.
    ///
    /// Note that this ideally would be `into_handle` taking `Resource<T>` by
    /// ownership. The code generator does not enable that in all situations,
    /// unfortunately, so this is provided instead.
    ///
    /// Also note that `take_handle` is in theory only ever called on values
    /// owned by a generated function. For example a generated function might
    /// take `Resource<T>` as an argument but then call `take_handle` on a
    /// reference to that argument. In that sense the dynamic nature of
    /// `take_handle` should only be exposed internally to generated code, not
    /// to user code.
    #[doc(hidden)]
    pub fn take_handle(resource: &Resource<T>) -> u32 {
        resource.handle.swap(u32::MAX, Relaxed)
    }

    #[doc(hidden)]
    pub fn handle(resource: &Resource<T>) -> u32 {
        resource.handle.load(Relaxed)
    }

    /// Creates a new Rust-defined resource from the underlying representation
    /// `T`.
    ///
    /// This will move `T` onto the heap to create a single pointer to represent
    /// it which is then wrapped up in a component model resource.
    pub fn new(val: T) -> Resource<T>
    where
        T: RustResource,
    {
        let rep = Box::into_raw(Box::new(Some(val))) as usize;
        unsafe {
            let handle = T::new(rep);
            Resource::from_handle(handle)
        }
    }

    #[doc(hidden)]
    pub unsafe fn dtor(rep: usize)
    where
        T: RustResource,
    {
        let _ = Box::from_raw(rep as *mut RawRep<T>);
    }

    /// Takes back ownership of the object, dropping the resource handle.
    pub fn into_inner(resource: Self) -> T
    where
        T: RustResource,
    {
        unsafe {
            let rep = T::rep(resource.handle.load(Relaxed));
            RawRep::take(&mut *(rep as *mut RawRep<T>)).unwrap()
        }
    }

    #[doc(hidden)]
    pub unsafe fn lift_borrow<'a>(rep: usize) -> &'a T
    where
        T: RustResource,
    {
        RawRep::as_ref(&*(rep as *const RawRep<T>)).unwrap()
    }
}

impl<T: RustResource> Deref for Resource<T> {
    type Target = T;

    fn deref(&self) -> &T {
        unsafe {
            let rep = T::rep(self.handle.load(Relaxed));
            RawRep::as_ref(&*(rep as *const RawRep<T>)).unwrap()
        }
    }
}

impl<T: RustResource> DerefMut for Resource<T> {
    fn deref_mut(&mut self) -> &mut T {
        unsafe {
            let rep = T::rep(self.handle.load(Relaxed));
            RawRep::as_mut(&mut *(rep as *mut RawRep<T>)).unwrap()
        }
    }
}

impl<T: WasmResource> fmt::Debug for Resource<T> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.debug_struct("Resource")
            .field("handle", &self.handle)
            .finish()
    }
}

impl<T: WasmResource> Drop for Resource<T> {
    fn drop(&mut self) {
        unsafe {
            match self.handle.load(Relaxed) {
                // If this handle was "taken" then don't do anything in the
                // destructor.
                u32::MAX => {}

                // ... but otherwise do actually destroy it with the imported
                // component model intrinsic as defined through `T`.
                other => T::drop(other),
            }
        }
    }
}