A Better Peekable

This crate provides BPeekable<I: Iterator> which is a wrapper over an iterator. You can call the usual iterator methods on BPeekable<I> like next() and others (untested at the moment), in addition to peek and peek_n which allow you to peek the inner iterator without consuming it. peek gives you a reference to the immediately available item to be consumed by a next() call, whereas peek_n allows you to peek n times ahead. Calling peek_n(0) is the same as calling peek.

peek and peek_n are idempotent which means calling them repeatedly on BPeekable should have no effects on the underlying iterator or any state of BPeekable.

Usage

We are going to test the idempotence of BPeekable using the following sequence of peek and peek_n calls. Feel free to file an issue if you test and find out if something doesn't match up.

```rust // Required for peek and peekn use betterpeekable::BetterPeekable;

fn main() { let vec = vec![ String::from("Hello"), String::from("World"), String::from("It's a nice day to make"), String::from("A better peekable iterator adaptor"), String::from("Peek_N and Peek are supposed to be"), String::from("Idempotent Methods"), ];

    let mut iter = vec.into_iter();
    let mut better_peeker = iter.better_peekable();

    assert_eq!(better_peeker.peek(), Some(&"Hello".to_string()));
    assert_eq!(better_peeker.peek(), Some(&"Hello".to_string()));
    assert_eq!(better_peeker.peek(), Some(&"Hello".to_string()));
    assert_eq!(better_peeker.peek_n(1), Some(&"World".to_string()));
    assert_eq!(better_peeker.next(), Some("Hello".to_string()));
    assert_eq!(better_peeker.next(), Some("World".to_string()));
    assert_eq!(
        better_peeker.peek(),
        Some(&"It's a nice day to make".to_string())
    );
    assert_eq!(
        better_peeker.peek_n(0),
        Some(&"It's a nice day to make".to_string())
    );
    assert_eq!(
        better_peeker.peek_n(1),
        Some(&"A better peekable iterator adaptor".to_string())
    );
    assert_eq!(
        better_peeker.nth(1),
        Some("A better peekable iterator adaptor".to_string())
    );
    assert_eq!(
        better_peeker.peek_n(1),
        Some(&"Idempotent Methods".to_string())
    );

```