Crate streaming_iterator

Streaming iterators.

The iterator APIs in the Rust standard library do not allow elements to be yielded which borrow from the iterator itself. That means, for example, that the std::io::Lines iterator must allocate a new String for each line rather than reusing an internal buffer. The StreamingIterator trait instead provides access to elements being iterated over only by reference rather than by value.

StreamingIterators cannot be used in Rust for loops, but while let loops offer a similar level of ergonomics:

while let Some(item) = iter.next() {
    // work with item
}

However, make sure to only use the above form with a mutable reference to an existing iterator, not with an expression that creates an iterator. For example, the following code will loop forever over the first element of the array:

use streaming_iterator::{convert, StreamingIterator};
let array = [0, 1, 2, 3];

while let Some(item) = convert(array.iter()).next() {
  // This is an infinite loop!
}

While the standard Iterator trait’s functionality is based off of the next method, StreamingIterator’s functionality is based off of a pair of methods: advance and get. This essentially splits the logic of next in half (in fact, StreamingIterator’s next method does nothing but call advance followed by get).

This is required because of Rust’s lexical handling of borrows (more specifically a lack of single entry, multiple exit borrows). If StreamingIterator was defined like Iterator with just a required next method, operations like filter would be impossible to define.

Structs

• Chain
  A streaming iterator that concatenates two streaming iterators
• Cloned
  A normal, non-streaming, iterator which converts the elements of a streaming iterator into owned values by cloning them.
• Convert
  A streaming iterator which yields elements from a normal, non-streaming, iterator.
• ConvertMut
  A streaming iterator which yields elements from an iterator of mutable references.
• ConvertRef
  A streaming iterator which yields elements from an iterator of references.
• Copied
  A normal, non-streaming, iterator which converts the elements of a streaming iterator into owned values by copying them.
• Empty
  A simple iterator that returns nothing.
• Filter
  A streaming iterator which filters the elements of a streaming iterator with a predicate.
• FilterMap
  An iterator which both filters and maps elements of a streaming iterator with a closure.
• FilterMapDeref
  A regular, non-streaming iterator which both filters and maps elements of a streaming iterator with a closure.
• FlatMap
  A streaming iterator that maps elements to iterators with a closure and then yields the concatenation of the obtained iterators
• Flatten
  A streaming iterator that flattens nested streaming iterators.
• FromFn
  A simple iterator that returns items from a function call.
• Fuse
  A streaming iterator which is well-defined before and after iteration.
• Inspect
  A streaming iterator that calls a function with element before yielding it.
• Map
  A streaming iterator which transforms the elements of a streaming iterator.
• MapDeref
  A regular, non-streaming iterator which transforms the elements of a streaming iterator.
• MapDerefMut
  A regular, non-streaming iterator which transforms the elements of a mutable streaming iterator.
• MapRef
  A streaming iterator which transforms the elements of a streaming iterator.
• Once
  A simple iterator that returns exactly one item.
• OnceWith
  A simple iterator that returns exactly one item from a function call.
• Repeat
  A simple iterator that repeats an item endlessly.
• RepeatWith
  A simple iterator that endlessly returns items from a function call.
• Rev
  A streaming iterator which returns elements in the opposite order.
• Skip
  A streaming iterator which skips a number of elements in a streaming iterator.
• SkipWhile
  A streaming iterator which skips initial elements that match a predicate
• Successors
  An iterator where each successive item is computed from the preceding one.
• Take
  A streaming iterator which only yields a limited number of elements in a streaming iterator.
• TakeWhile
  A streaming iterator which only returns initial elements matching a predicate.
• WindowsMut
  A streaming iterator which returns overlapping mutable subslices of length size.

Traits

• DoubleEndedStreamingIterator
  A streaming iterator able to yield elements from both ends.
• DoubleEndedStreamingIteratorMut
  A mutable streaming iterator able to yield elements from both ends.
• IntoStreamingIterator
  Conversion from IntoIterator to StreamingIterator.
• StreamingIterator
  An interface for dealing with streaming iterators.
• StreamingIteratorMut
  An interface for dealing with mutable streaming iterators.

Functions

• convert
  Turns a normal, non-streaming iterator into a streaming iterator.
• convert_mut
  Turns an iterator of mutable references into a streaming iterator.
• convert_ref
  Turns an iterator of references into a streaming iterator.
• empty
  Creates an empty iterator.
• from_fn
  Creates an iterator that returns items from a function call.
• once
  Creates an iterator that returns exactly one item.
• once_with
  Creates an iterator that returns exactly one item from a function call.
• repeat
  Creates an iterator that returns an item endlessly.
• repeat_with
  Creates an iterator that endlessly returns items from a function call.
• successors
  Creates an iterator where each successive item is computed from the preceding one.
• windows_mut
  Creates an iterator over all contiguous windows of length size in a mutable slice.