clone_dyn_types/

lib.rs

#![no_std]
#![doc(html_logo_url = "https://raw.githubusercontent.com/Wandalen/wTools/master/asset/img/logo_v3_trans_square.png")]
#![doc(
  html_favicon_url = "https://raw.githubusercontent.com/Wandalen/wTools/alpha/asset/img/logo_v3_trans_square_icon_small_v2.ico"
)]
#![doc(html_root_url = "https://docs.rs/clone_dyn_types/latest/clone_dyn_types/")]
#![ cfg_attr( doc, doc = include_str!( concat!( env!( "CARGO_MANIFEST_DIR" ), "/", "readme.md" ) ) ) ]
#![ cfg_attr( not( doc ), doc = "Clone trait object types" ) ]

/// Namespace with dependencies.
#[ cfg( feature = "enabled" ) ]
pub mod dependency
{
}

/// Define a private namespace for all its items.
// #[ cfg( any( not( feature = "no_std" ), feature = "use_alloc" ) ) ]
#[ cfg( feature = "enabled" ) ]
mod private
{

  // xxx: ?
  // #[ cfg( any( not( feature = "no_std" ), feature = "use_alloc" ) ) ]
  extern crate alloc;
  // #[ cfg( any( not( feature = "no_std" ), feature = "use_alloc" ) ) ]
  // #[ allow( unused_imports ) ]
  use alloc::boxed::Box;
  // #[ cfg( all( feature = "use_std", not( feature = "use_alloc" ) ) ) ]
  // use std::boxed::Box;

  /// A trait to upcast a clonable entity and clone it.
  /// It's implemented for all entities which can be cloned.
  pub trait CloneDyn: Sealed {
  #[ doc( hidden ) ]
  fn __clone_dyn(&self, _ : DontCallMe) -> *mut ();
 }

  // clonable
  impl< T > CloneDyn for T
  where
  T: Clone,
  {
  #[ inline ]
  #[ allow( clippy::implicit_return, clippy::as_conversions, clippy::ptr_as_ptr ) ]
  fn __clone_dyn(&self, _ : DontCallMe) -> *mut ()
  {
   Box::< T >::into_raw(Box::new(self.clone())) as *mut ()
  }
 }

  // slice
  impl< T > CloneDyn for [T]
  where
  T: Clone,
  {
  #[ inline ]
  #[ allow( clippy::implicit_return, clippy::as_conversions, clippy::ptr_as_ptr ) ]
  fn __clone_dyn(&self, _ : DontCallMe) -> *mut ()
  {
   Box::< [T] >::into_raw(self.iter().cloned().collect()) as *mut ()
  }
 }

  // str slice
  impl CloneDyn for str 
  {
  #[ inline ]
  #[ allow( clippy ::as_conversions, clippy ::ptr_as_ptr, clippy ::implicit_return ) ]
  fn __clone_dyn(&self, _: DontCallMe) -> *mut () 
  {
   Box::< str >::into_raw(Box::from(self)) as *mut ()
 }
 }

  ///
  /// True clone which is applicable not only to clonable entities, but to trait objects implementing `CloneDyn`.
  ///
  /// # Example
  ///
  /// ```
  /// use clone_dyn_types::clone;
  ///
  /// #[ derive( Clone ) ]
  /// struct MyStruct
  /// {
  ///   value: i32,
  /// }
  ///
  /// let original = MyStruct { value: 42 };
  /// let cloned = clone( &original );
  ///
  /// assert_eq!( original.value, cloned.value );
  /// ```
  #[ inline ]
  pub fn clone< T >(src : &T) -> T
  where
  T: CloneDyn,
  {
  // # Safety
  //
  // This function uses an `unsafe` block because it performs low-level memory manipulations. Specifically, it handles
  // raw pointers and converts them to and from `Box< T >`. This is necessary to dynamically clone a trait object, which
  // does not support cloning through the standard `Clone` trait. The safety of this function depends on the guarantee
  // that the `CloneDyn` trait is correctly implemented for the given type `T`, ensuring that `__clone_dyn` returns a
  // valid pointer to a cloned instance of `T`.
  //
  #[ allow( unsafe_code,
   clippy::as_conversions,
   clippy::ptr_as_ptr,
   clippy::implicit_return,
   clippy::undocumented_unsafe_blocks ) ]
  unsafe
  {
   *Box::from_raw(< T as CloneDyn >::__clone_dyn(src, DontCallMe) as *mut T)
 }
 }

  ///
  /// Clone boxed dyn.
  ///
  /// Clones a dynamically sized trait object into a `Box< T >`.
  ///
  /// # Example
  ///
  /// ```
  /// use clone_dyn_types::{ CloneDyn, clone_into_box };
  ///
  /// #[ derive( Clone ) ]
  /// struct MyStruct
  /// {
  ///   value: i32,
  /// }
  ///
  /// trait MyTrait: CloneDyn
  /// {
  ///   fn val( &self ) -> i32;
  /// }
  ///
  /// impl MyTrait for MyStruct
  /// {
  ///   fn val( &self ) -> i32
  ///   {
  ///     self.value
  /// }
  /// }
  ///
  /// #[ allow( non_local_definitions ) ]
  /// impl < 'c > Clone
  /// for Box< dyn MyTrait + 'c >
  /// {
  ///   #[ inline ]
  ///   fn clone( &self ) -> Self { clone_into_box( &**self ) }
  /// }
  ///
  /// #[ allow( non_local_definitions ) ]
  /// impl < 'c > Clone
  /// for Box< dyn MyTrait + Send + 'c >
  /// {
  ///   #[ inline ]
  ///   fn clone( &self ) -> Self { clone_into_box( &**self ) }
  /// }
  ///
  /// #[ allow( non_local_definitions ) ]
  /// impl < 'c > Clone
  /// for Box< dyn MyTrait + Sync + 'c >
  /// {
  ///   #[ inline ]
  ///   fn clone( &self ) -> Self { clone_into_box( &**self ) }
  /// }
  ///
  /// #[ allow( non_local_definitions ) ]
  /// impl < 'c > Clone
  /// for Box< dyn MyTrait + Send + Sync + 'c >
  /// {
  ///   #[ inline ]
  ///   fn clone( &self ) -> Self { clone_into_box( &**self ) }
  /// }
  ///
  /// let cloned: Box< dyn MyTrait > = clone_into_box( &MyStruct { value: 42 } );
  ///
  /// ```
  #[ inline ]
  pub fn clone_into_box< T >(ref_dyn : &T) -> Box< T >
  where
  T: ?Sized + CloneDyn,
  {
  // # Safety
  //
  // This function uses an `unsafe` block because it performs low-level memory manipulations involving raw pointers.
  // The `unsafe` block is necessary here because we're manually handling raw pointers and converting them to and from
  // `Box< T >`. This bypasses Rust's ownership and borrowing rules to achieve dynamic cloning of a boxed trait object.
  // The safety of this function relies on the correct implementation of the `CloneDyn` trait for the given type `T`.
  // Specifically, `__clone_dyn` must return a valid pointer to a cloned instance of `T`.
  //
  #[ allow( unsafe_code,
   clippy::implicit_return,
   clippy::as_conversions,
   clippy::ptr_cast_constness,
   clippy::ptr_as_ptr,
   clippy::multiple_unsafe_ops_per_block,
   clippy::undocumented_unsafe_blocks,
   clippy::ref_as_ptr,
   clippy::borrow_as_ptr ) ]
  unsafe
  {
   let mut ptr = ref_dyn as *const T;
   #[ allow( clippy::borrow_as_ptr ) ]
   let data_ptr = &mut ptr as *mut *const T as *mut *mut (); // don't change it
          // qqq: xxx: after atabilization try `&raw mut ptr` instead
          // let data_ptr = &raw mut ptr as *mut *mut (); // fix clippy
   *data_ptr = < T as CloneDyn >::__clone_dyn(ref_dyn, DontCallMe);
   Box::from_raw(ptr as *mut T)
 }
 }

  #[ doc( hidden ) ]
  mod sealed
  {
  #[ doc( hidden ) ]
  #[ allow( missing_debug_implementations ) ]
  pub struct DontCallMe;
  #[ doc( hidden ) ]
  pub trait Sealed {}
  impl< T: Clone > Sealed for T {}
  impl< T: Clone > Sealed for [T] {}
  impl Sealed for str {}
 }
  use sealed :: { DontCallMe, Sealed };
}

#[ cfg( feature = "enabled" ) ]
#[ doc( inline ) ]
#[ allow( unused_imports ) ]
#[ allow( clippy ::pub_use ) ]
pub use own :: *;

/// Own namespace of the module.
#[ cfg( feature = "enabled" ) ]
#[ allow( unused_imports ) ]
pub mod own 
{
  use super ::orphan;
  #[ doc( inline ) ]
  #[ allow( clippy ::useless_attribute, clippy ::pub_use ) ]
  pub use orphan :: *;
}

/// Orphan namespace of the module.
#[ cfg( feature = "enabled" ) ]
#[ allow( unused_imports ) ]
pub mod orphan 
{
  use super ::exposed;
  #[ doc( inline ) ]
  #[ allow( clippy ::useless_attribute, clippy ::pub_use ) ]
  pub use exposed :: *;
}

/// Exposed namespace of the module.
#[ cfg( feature = "enabled" ) ]
#[ allow( unused_imports ) ]
pub mod exposed 
{
  use super ::prelude;
  #[ doc( inline ) ]
  #[ allow( clippy ::useless_attribute, clippy ::pub_use ) ]
  pub use prelude :: *;
}

/// Prelude to use essentials: `use my_module ::prelude :: *`.
#[ cfg( feature = "enabled" ) ]
#[ allow( unused_imports ) ]
pub mod prelude 
{
  use super ::private;
  #[ doc( inline ) ]
  #[ allow( clippy ::useless_attribute, clippy ::pub_use ) ]
  pub use private :: { CloneDyn, clone_into_box, clone };
}