use type_constructor::prelude::*;

use core::fmt;
types!
{
  #[ derive( Debug ) ]
  pub pair MyHomoPair : < T : fmt::Debug >;
}
let x = MyHomoPair( 13, 31 );
dbg!( &x );
// prints : &x = MyHomoPair( 13, 31 )
let clone_as_array : [ i32 ; 2 ] = x.clone_as_array();
dbg!( &clone_as_array );
// prints : &clone_as_array = [ 13, 31 ]
let clone_as_tuple : ( i32 , i32 ) = x.clone_as_tuple();
dbg!( &clone_as_tuple );
// prints : &clone_as_tuple = ( 13, 31 )

它生成代码

use type_constructor::prelude::*;
use core::fmt;

#[ derive( Debug ) ]
pub struct MyHomoPair< T >( pub T, pub T );

impl< T > core::ops::Deref for MyHomoPair< T >
{
  type Target = ( T, T );

  fn deref( &self ) -> &Self::Target
  {
    #[ cfg( debug_assertions ) ]
    {
      let layout1 = std::alloc::Layout::new::< Self >();
      let layout2 = std::alloc::Layout::new::< Self::Target >();
      debug_assert_eq!( layout1, layout2 );
    }
    unsafe { std::mem::transmute::< _, _ >( self ) }
  }
}

impl< T > core::ops::DerefMut for MyHomoPair< T >
{
  fn deref_mut( &mut self ) -> &mut Self::Target
  {
    #[ cfg( debug_assertions ) ]
    {
      let layout1 = std::alloc::Layout::new::< Self >();
      let layout2 = std::alloc::Layout::new::< Self::Target >();
      debug_assert_eq!( layout1, layout2 );
    }
    unsafe { std::mem::transmute::< _, _ >( self ) }
  }
}

impl< T > From< ( T, T ) > for MyHomoPair< T >
{
  fn from( src : ( T, T ) ) -> Self { Self( src.0, src.1 ) }
}

impl< T > From< MyHomoPair< T >> for ( T, T )
{
  fn from( src : MyHomoPair< T > ) -> Self { ( src.0, src.1 ) }
}

impl< T > From< [ T; 2 ] > for MyHomoPair< T >
where
  T : Clone,
{
  fn from( src : [ T; 2 ] ) -> Self { Self( src[ 0 ].clone(), src[ 1 ].clone() ) }
}

impl< T > From< MyHomoPair< T >> for [ T; 2 ]
{
  fn from( src : MyHomoPair< T > ) -> Self { [ src.0, src.1 ] }
}

impl< T > From< &[ T ] > for MyHomoPair< T >
where
  T : Clone,
{
  fn from( src : &[ T ] ) -> Self
  {
    debug_assert_eq!( src.len(), 2 );
    Self( src[ 0 ].clone(), src[ 1 ].clone() )
  }
}

impl< T > From< T > for MyHomoPair< T >
where
  T : Clone,
{
  fn from( src : T ) -> Self { Self( src.clone(), src.clone() ) }
}

impl< T > CloneAsTuple< ( T, T ) > for MyHomoPair< T >
where
  T : Clone,
{
  fn clone_as_tuple( &self ) -> ( T, T ) { ( self.0.clone(), self.1.clone() ) }
}

impl< T > CloneAsArray< T, 2 > for MyHomoPair< T >
where
  T : Clone,
{
  fn clone_as_array( &self ) -> [ T; 2 ] { [ self.0.clone(), self.1.clone() ] }
}

impl< T > AsTuple< ( T, T ) > for MyHomoPair< T >
{
  fn as_tuple( &self ) -> &( T, T ) { unsafe { std::mem::transmute::< &_, &( T, T ) >( self ) } }
}

impl< T > AsArray< T, 2 > for MyHomoPair< T >
{
  fn as_array( &self ) -> &[ T; 2 ] { unsafe { std::mem::transmute::< &_, &[ T; 2 ] >( self ) } }
}

impl< T > AsSlice< T > for MyHomoPair< T >
{
  fn as_slice( &self ) -> &[ T ] { &self.as_array()[ .. ] }
}

#[ cfg( feature = "make" ) ]
impl< T > From_0 for MyHomoPair< T >
where
  T : Default,
{
  fn from_0() -> Self { Self( Default::default(), Default::default() ) }
}

#[ cfg( feature = "make" ) ]
impl< T > From_1< T > for MyHomoPair< T >
where
  T : Clone,
{
  fn from_1( _0 : T ) -> Self { Self( _0.clone(), _0.clone() ) }
}

#[ cfg( feature = "make" ) ]
impl< T > From_2< T, T > for MyHomoPair< T >
{
  fn from_2( _0 : T, _1 : T ) -> Self { Self( _0, _1 ) }
}

/* ... */

let x = MyHomoPair( 13, 31 );
dbg!( &x );
// prints : &x = MyHomoPair( 13, 31 )
let clone_as_array : [ i32 ; 2 ] = x.clone_as_array();
dbg!( &clone_as_array );
// prints : &clone_as_array = [ 13, 31 ]
let clone_as_tuple : ( i32 , i32 ) = x.clone_as_tuple();
dbg!( &clone_as_tuple );
// prints : &clone_as_tuple = ( 13, 31 )

基本用例 :: 单行多个元素

使用类型构造函数 many 将 Vec 包裹在元组中。类似于 single，它为其实现了必要的特质。

// #[ cfg
// (
//   all
//   (
//     feature = "many",
//     any( not( feature = "no_std" ), feature = "use_alloc" ),
//   )
// ) ]
// {
//   use type_constructor::prelude::*;
//
//   types!( pub many MyMany : i32 );
//   let x = MyMany::from( [ 1, 2, 3 ] );
//   println!( "x : {:?}", x.0 );
// }

它生成代码

use type_constructor::prelude::*;

pub struct MyMany( pub std::vec::Vec< i32 > );

impl core::ops::Deref for MyMany
{
  type Target = std::vec::Vec< i32 >;

  fn deref( &self ) -> &Self::Target { &self.0 }
}

impl core::ops::DerefMut for MyMany
{
  fn deref_mut( &mut self ) -> &mut Self::Target { &mut self.0 }
}

impl From< i32 > for MyMany
{
  fn from( src : i32 ) -> Self { Self( vec![ src ] ) }
}

impl From< ( i32, ) > for MyMany
{
  fn from( src : ( i32, ) ) -> Self { Self( vec![ src.0 ] ) }
}

impl< const N: usize > From< [ i32; N ] > for MyMany
where
  i32 : Clone,
{
  fn from( src : [ i32; N ] ) -> Self { Self( std::vec::Vec::from( src ) ) }
}

impl From< &[ i32 ] > for MyMany
where
  i32 : Clone,
{
  fn from( src : &[ i32 ] ) -> Self
  {
    debug_assert_eq!( src.len(), 1 );
    Self( std::vec::Vec::from( src ) )
  }
}

impl AsSlice< i32 > for MyMany
where
  i32 : Clone,
{
  fn as_slice( &self ) -> &[ i32 ] { &self[ .. ] }
}

#[ cfg( feature = "make" ) ]
impl From_0 for MyMany
{
  fn from_0() -> Self { Self( std::vec::Vec::< i32 >::new() ) }
}

#[ cfg( feature = "make" ) ]
impl From_1< i32 > for MyMany
{
  fn from_1( _0 : i32 ) -> Self { Self( vec![ _0 ] ) }
}

#[ cfg( feature = "make" ) ]
impl From_2< i32, i32 > for MyMany
{
  fn from_2( _0 : i32, _1 : i32 ) -> Self { Self( vec![ _0, _1 ] ) }
}

#[ cfg( feature = "make" ) ]
impl From_3< i32, i32, i32 > for MyMany
{
  fn from_3( _0 : i32, _1 : i32, _2 : i32 ) -> Self { Self( vec![ _0, _1, _2 ] ) }
}

/* ... */

let x = MyMany::from( [ 1, 2, 3 ] );
println!( "x : {:?}", x.0 );

基本用例 :: make - 可变参数构造函数

实现特性 [From_0]、[From_1] 直至 MakeN，以提供接口，使用不同的参数集来构造你的结构。在这个示例结构中，Struct1 可以不带参数、带单个参数或带两个参数来构造。

• 不带参数的构造函数将字段填充为零。
• 带单个参数的构造函数将两个字段都设置为参数的值。
• 带两个参数的构造函数设置每个字段的单独值。

#[ cfg( feature = "make" ) ]
{
  use type_constructor::prelude::*;

  #[ derive( Debug, PartialEq ) ]
  struct Struct1
  {
    a : i32,
    b : i32,
  }

  impl From_0 for Struct1
  {
    fn from_0() -> Self
    {
      Self { a : 0, b : 0 }
    }
  }

  impl From_1< i32 > for Struct1
  {
    fn from_1( val : i32 ) -> Self
    {
      Self { a : val, b : val }
    }
  }

  impl From_2< i32, i32 > for Struct1
  {
    fn from_2( val1 : i32, val2 : i32 ) -> Self
    {
      Self { a : val1, b : val2 }
    }
  }

  let got : Struct1 = from!();
  let exp = Struct1{ a : 0, b : 0 };
  assert_eq!( got, exp );

  let got : Struct1 = from!( 13 );
  let exp = Struct1{ a : 13, b : 13 };
  assert_eq!( got, exp );

  let got : Struct1 = from!( 1, 3 );
  let exp = Struct1{ a : 1, b : 3 };
  assert_eq!( got, exp );
}

将它们添加到你的项目中

cargo add type_constructor

从仓库中尝试使用

git clone https://github.com/Wandalen/wTools
cd wTools
cd examples/type_constructor_trivial_sample
cargo run