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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.pub(crate) type AtomicPtr<T> = *mut T;#[allow(unused)]pub(crate) struct RawBytes {  ptr: *const u8,  len: usize,  // inlined "trait object"  data: AtomicPtr<()>,  vtable: &'static Vtable,}
impl RawBytes {  pub fn new_raw(    ptr: *const u8,    len: usize,    data: AtomicPtr<()>,    vtable: &'static Vtable,  ) -> bytes::Bytes {    RawBytes {      ptr,      len,      data,      vtable,    }    .into()  }}
// Validate some bytes::Bytes layout assumptions at compile time.const _: () = {  assert!(    core::mem::size_of::<RawBytes>() == core::mem::size_of::<bytes::Bytes>(),  );  assert!(    core::mem::align_of::<RawBytes>() == core::mem::align_of::<bytes::Bytes>(),  );};
#[allow(unused)]pub(crate) struct Vtable {  /// fn(data, ptr, len)  pub clone: unsafe fn(&AtomicPtr<()>, *const u8, usize) -> bytes::Bytes,  /// fn(data, ptr, len)  ///  /// takes `Bytes` to value  pub to_vec: unsafe fn(&AtomicPtr<()>, *const u8, usize) -> Vec<u8>,  /// fn(data, ptr, len)  pub drop: unsafe fn(&mut AtomicPtr<()>, *const u8, usize),}
impl From<RawBytes> for bytes::Bytes {  fn from(b: RawBytes) -> Self {    // SAFETY: RawBytes has the same layout as bytes::Bytes    // this is tested below, both are composed of usize-d ptrs/values    // thus aren't currently subject to rust's field re-ordering to minimize padding    unsafe { std::mem::transmute(b) }  }}
#[cfg(test)]mod tests {  use super::*;  use std::mem;
  const HELLO: &str = "hello";
  // ===== impl StaticVtable =====
  const STATIC_VTABLE: Vtable = Vtable {    clone: static_clone,    drop: static_drop,    to_vec: static_to_vec,  };
  unsafe fn static_clone(    _: &AtomicPtr<()>,    ptr: *const u8,    len: usize,  ) -> bytes::Bytes {    from_static(std::slice::from_raw_parts(ptr, len)).into()  }
  unsafe fn static_to_vec(    _: &AtomicPtr<()>,    ptr: *const u8,    len: usize,  ) -> Vec<u8> {    let slice = std::slice::from_raw_parts(ptr, len);    slice.to_vec()  }
  unsafe fn static_drop(_: &mut AtomicPtr<()>, _: *const u8, _: usize) {    // nothing to drop for &'static [u8]  }
  fn from_static(bytes: &'static [u8]) -> RawBytes {    RawBytes {      ptr: bytes.as_ptr(),      len: bytes.len(),      data: std::ptr::null_mut(),      vtable: &STATIC_VTABLE,    }  }
  #[test]  fn bytes_identity() {    let b1: bytes::Bytes = from_static(HELLO.as_bytes()).into();    let b2 = bytes::Bytes::from_static(HELLO.as_bytes());    assert_eq!(b1, b2); // Values are equal  }
  #[test]  fn bytes_layout() {    let u1: [usize; 4] =      // SAFETY: ensuring layout is the same      unsafe { mem::transmute(from_static(HELLO.as_bytes())) };    let u2: [usize; 4] =      // SAFETY: ensuring layout is the same      unsafe { mem::transmute(bytes::Bytes::from_static(HELLO.as_bytes())) };    assert_eq!(u1[..3], u2[..3]); // Struct bytes are equal besides Vtables  }}