Iterators

Iterators

• Iterator is a trait, with an Item associated type

• Produces a sequence of Option<Item> values on calls to its next() method

• Ubiquitous in Rust code

Iterator Adapters

• Implementation of Iterator() that operates by consuming the output of some passed iterator; essentially iterators over iterators

• Ubiquitous in Rust code

• Book pp. 329-351 are a bestiary of Standard Library stuff, worth studying in detail

FromIterator

• Trait used by collect() to make an iterator into a collection

• Can implement for your collection type to make it collectible

IntoIterator

• Trait for getting a "canonical" iterator for a type

• Makes the type work with for loops

    trait IntoIterator where Self::IntoIter::Item == Self::Item {
        type Item;
        type IntoIter: Iterator;
        fn into_iter(self) -> Self::IntoIter;
    }
  

• Every Iterator has a default implementation of IntoIterator, so that you can for loop over an explicit iterator

Implementing an Iterator

• Let's look at a "Neighborhood" iterator, which examines the squares around a target square in a grid. (playground)