daily pastebin goal
4%
SHARE
TWEET

Untitled

a guest Jan 17th, 2019 74 Never
Not a member of Pastebin yet? Sign Up, it unlocks many cool features!
  1. use std::ops::*;
  2.  
  3. fn main()
  4. {
  5.     let iter: MyIterator<f32> = MyIterator::new();
  6.     for (i, val) in iter.take(10).enumerate() {
  7.         println!("{} => {}", i, val);
  8.     }
  9. }
  10.  
  11. struct MyIterator<T: MyType>
  12. {
  13.     previous: T::InnerType,
  14. }
  15.  
  16. impl<T: MyType> MyIterator<T>
  17. {
  18.     pub fn new() -> Self {
  19.         MyIterator { previous: T::InnerType::ONE }
  20.     }
  21. }
  22.  
  23. // `Add`, `Shl`, and `From` trait bounds only work when put here...
  24. impl<T: MyType> Iterator for MyIterator<T>
  25. {
  26.     type Item = T;
  27.    
  28.     fn next(&mut self) -> Option<Self::Item> {
  29.         // Add one
  30.         let plus_one = T::InnerType::from(self.previous + T::InnerType::ONE);
  31.        
  32.         // Multiply by two
  33.         let times_two = T::InnerType::from(plus_one << 1);
  34.        
  35.         // Save state
  36.         self.previous = times_two;
  37.        
  38.         // Return value
  39.         Some(T::from_inner(times_two))
  40.     }
  41. }
  42.  
  43. trait MyType
  44. {
  45.     // Want to put `Add`, `Shl`, and `From` trait bounds on InnerType here...
  46.     type InnerType:
  47.             One + Copy + Add + Shl<usize> +
  48.             From<<Self::InnerType as Add>::Output> +
  49.             From<<Self::InnerType as Shl<usize>>::Output>;
  50.  
  51.     fn from_inner(val: Self::InnerType) -> Self;
  52. }
  53.  
  54. impl MyType for f32
  55. {
  56.     type InnerType = u32;
  57.    
  58.     fn from_inner(val: u32) -> f32 {
  59.         val as f32
  60.     }
  61. }
  62.  
  63. trait One
  64. {
  65.     const ONE: Self;
  66. }
  67.  
  68. impl One for u32
  69. {
  70.     const ONE: u32 = 1;
  71. }
RAW Paste Data
We use cookies for various purposes including analytics. By continuing to use Pastebin, you agree to our use of cookies as described in the Cookies Policy. OK, I Understand
 
Top