Trait StepCount

pub trait StepCount: Iterator {
    // Provided methods
    fn step_count<T: Step + Default>(self) -> T
       where Self: Sized { ... }
    fn step_count_from<T: Step>(self, start: T) -> T
       where Self: Sized { ... }
    fn step_count_checked<T: Step + Default>(self) -> Option<T>
       where Self: Sized { ... }
    fn step_count_from_checked<T: Step>(self, start: T) -> Option<T>
       where Self: Sized { ... }
}

Convenience trait to allow using step_count* functions as methods. This trait is implemented for every Iterator.

Provided Methods

fn step_count<T: Step + Default>(self) -> T

where Self: Sized,

Consumes the iterator, counting the number of iterations. This uses the Step trait to keep track of the count of iterations. The count starts from the default value provided by the Default trait.

Panics

Panics if the count exceeds the capacity of the count type (T).

Examples

Basic usage:

let arr = [1, 2, 3];
let count: usize = arr.into_iter().step_count();
assert_eq!(count, 3);

Overflow:

let range = 0..u8::MAX as usize + 1;
range.step_count::<u8>();

fn step_count_from<T: Step>(self, start: T) -> T

where Self: Sized,

Consumes the iterator, counting the number of iterations, starting from a given value. This uses the Step trait to keep track of the count of iterations.

Panics

Panics if the count exceeds the capacity of the count type (T).

Examples

Basic usage:

let arr = [1, 2, 3];
let count: u16 = arr.into_iter().step_count_from(2);
assert_eq!(count, 5);

Overflow:

let range = 0..u8::MAX as usize - 1;
range.step_count_from::<u8>(2);

fn step_count_checked<T: Step + Default>(self) -> Option<T>

where Self: Sized,

Consumes the iterator, counting the number of iterations. This uses the Step trait to keep track of the count of iterations. The count starts from the default value provided by the Default trait. Returns None if the count exceeded the capcity of the count type (T).

This function always fully consumes the iterator, even if None is returned.

Examples

Basic usage:

let arr = [1, 2, 3];
let count: Option<u16> = arr.into_iter().step_count_checked();
assert_eq!(count, Some(3));

Overflow:

let range = 0..u8::MAX as usize + 1;
let count: Option<u8> = range.step_count_checked();
assert!(count.is_none());

Consumption:

let mut range = -1..u8::MAX as isize;
let count: Option<u8> = range.by_ref().step_count_checked();
assert!(count.is_none());
assert!(range.is_empty());

fn step_count_from_checked<T: Step>(self, start: T) -> Option<T>

where Self: Sized,

Consumes the iterator, counting the number of iterations, starting from a given value. This uses the Step trait to keep track of the count of iterations. Returns None if the count exceeded the capcity of the count type (T).

This function always fully consumes the iterator, even if None is returned.

Examples

Basic usage:

let arr = [1, 2, 3];
let count: Option<u16> = arr.into_iter().step_count_from_checked(2);
assert_eq!(count, Some(5));

Overflow:

let range = 0..u8::MAX as usize - 1;
let count: Option<u8> = range.step_count_from_checked(2);
assert!(count.is_none());

Consumption:

let mut range = -2..i8::MAX as isize;
let count: Option<i8> = range.by_ref().step_count_from_checked(-1);
assert!(count.is_none());
assert!(range.is_empty());

Implementors

impl<T: Iterator> StepCount for T