library/core/tests/iter/traits/step.rs

   1 use core::iter::*;
   2
   3 #[test]
   4 fn test_steps_between() {
   5     assert_eq!(Step::steps_between(&20_u8, &200_u8), Some(180_usize));
   6     assert_eq!(Step::steps_between(&-20_i8, &80_i8), Some(100_usize));
   7     assert_eq!(Step::steps_between(&-120_i8, &80_i8), Some(200_usize));
   8     assert_eq!(Step::steps_between(&20_u32, &4_000_100_u32), Some(4_000_080_usize));
   9     assert_eq!(Step::steps_between(&-20_i32, &80_i32), Some(100_usize));
  10     assert_eq!(Step::steps_between(&-2_000_030_i32, &2_000_050_i32), Some(4_000_080_usize));
  11
  12     // Skip u64/i64 to avoid differences with 32-bit vs 64-bit platforms
  13
  14     assert_eq!(Step::steps_between(&20_u128, &200_u128), Some(180_usize));
  15     assert_eq!(Step::steps_between(&-20_i128, &80_i128), Some(100_usize));
  16     if cfg!(target_pointer_width = "64") {
  17         assert_eq!(Step::steps_between(&10_u128, &0x1_0000_0000_0000_0009_u128), Some(usize::MAX));
  18     }
  19     assert_eq!(Step::steps_between(&10_u128, &0x1_0000_0000_0000_000a_u128), None);
  20     assert_eq!(Step::steps_between(&10_i128, &0x1_0000_0000_0000_000a_i128), None);
  21     assert_eq!(
  22         Step::steps_between(&-0x1_0000_0000_0000_0000_i128, &0x1_0000_0000_0000_0000_i128,),
  23         None,
  24     );
  25 }
  26
  27 #[test]
  28 fn test_step_forward() {
  29     assert_eq!(Step::forward_checked(55_u8, 200_usize), Some(255_u8));
  30     assert_eq!(Step::forward_checked(252_u8, 200_usize), None);
  31     assert_eq!(Step::forward_checked(0_u8, 256_usize), None);
  32     assert_eq!(Step::forward_checked(-110_i8, 200_usize), Some(90_i8));
  33     assert_eq!(Step::forward_checked(-110_i8, 248_usize), None);
  34     assert_eq!(Step::forward_checked(-126_i8, 256_usize), None);
  35
  36     assert_eq!(Step::forward_checked(35_u16, 100_usize), Some(135_u16));
  37     assert_eq!(Step::forward_checked(35_u16, 65500_usize), Some(u16::MAX));
  38     assert_eq!(Step::forward_checked(36_u16, 65500_usize), None);
  39     assert_eq!(Step::forward_checked(-110_i16, 200_usize), Some(90_i16));
  40     assert_eq!(Step::forward_checked(-20_030_i16, 50_050_usize), Some(30_020_i16));
  41     assert_eq!(Step::forward_checked(-10_i16, 40_000_usize), None);
  42     assert_eq!(Step::forward_checked(-10_i16, 70_000_usize), None);
  43
  44     assert_eq!(Step::forward_checked(10_u128, 70_000_usize), Some(70_010_u128));
  45     assert_eq!(Step::forward_checked(10_i128, 70_030_usize), Some(70_040_i128));
  46     assert_eq!(
  47         Step::forward_checked(0xffff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_u128, 0xff_usize),
  48         Some(u128::MAX),
  49     );
  50     assert_eq!(
  51         Step::forward_checked(0xffff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_u128, 0x100_usize),
  52         None
  53     );
  54     assert_eq!(
  55         Step::forward_checked(0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0xff_usize),
  56         Some(i128::MAX),
  57     );
  58     assert_eq!(
  59         Step::forward_checked(0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0x100_usize),
  60         None
  61     );
  62 }
  63
  64 #[test]
  65 fn test_step_backward() {
  66     assert_eq!(Step::backward_checked(255_u8, 200_usize), Some(55_u8));
  67     assert_eq!(Step::backward_checked(100_u8, 200_usize), None);
  68     assert_eq!(Step::backward_checked(255_u8, 256_usize), None);
  69     assert_eq!(Step::backward_checked(90_i8, 200_usize), Some(-110_i8));
  70     assert_eq!(Step::backward_checked(110_i8, 248_usize), None);
  71     assert_eq!(Step::backward_checked(127_i8, 256_usize), None);
  72
  73     assert_eq!(Step::backward_checked(135_u16, 100_usize), Some(35_u16));
  74     assert_eq!(Step::backward_checked(u16::MAX, 65500_usize), Some(35_u16));
  75     assert_eq!(Step::backward_checked(10_u16, 11_usize), None);
  76     assert_eq!(Step::backward_checked(90_i16, 200_usize), Some(-110_i16));
  77     assert_eq!(Step::backward_checked(30_020_i16, 50_050_usize), Some(-20_030_i16));
  78     assert_eq!(Step::backward_checked(-10_i16, 40_000_usize), None);
  79     assert_eq!(Step::backward_checked(-10_i16, 70_000_usize), None);
  80
  81     assert_eq!(Step::backward_checked(70_010_u128, 70_000_usize), Some(10_u128));
  82     assert_eq!(Step::backward_checked(70_020_i128, 70_030_usize), Some(-10_i128));
  83     assert_eq!(Step::backward_checked(10_u128, 7_usize), Some(3_u128));
  84     assert_eq!(Step::backward_checked(10_u128, 11_usize), None);
  85     assert_eq!(
  86         Step::backward_checked(-0x7fff_ffff_ffff_ffff__ffff_ffff_ffff_ff00_i128, 0x100_usize),
  87         Some(i128::MIN)
  88     );
  89 }