6 releases
0.2.4 | Apr 29, 2022 |
---|---|
0.2.3 | Apr 19, 2022 |
0.1.3 | Apr 18, 2022 |
#1309 in Data structures
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8KB
97 lines
A Better Peekable
This crate provides a trait BetterPeekable
and a type BPeekable<I: Iterator>
which is a wrapper over an iterator and returned by calling better_peekable()
on any Iterator
. You can call the usual iterator methods on BPeekable<I>
just like next()
on I
. You can also call methods like next_back
,size_hint
and rposition
and everything else from DoubleEndedIterator
in addition to peek
and peek_n
.
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
. If you find a bug that violates this contract, please open an issue.
Usage
Add to better_peekable
to your Cargo.toml
.
[dependencies]
better_peekable = "0.2.4"
We are going to test the idempotence of BPeekable
using the following sequence of peek
and peek_n
calls.
// Required for peek and peek_n
use better_peekable::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())
);
Changelog 0.2.4 :
Removed trait bound std::fmt::Debug
bound from Iterator::Item