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//! Macros for delegating newtype iterators to inner types.
// Note: these place `impl` bounds at the end, as token gobbling is the only way
// I know how to consume an arbitrary list of constraints, with `$($args:tt)*`.
/// Creates a parallel iterator implementation which simply wraps an inner type
/// and delegates all methods inward. The actual struct must already be
/// declared with an `inner` field.
///
/// The implementation of `IntoParallelIterator` should be added separately.
macro_rules! delegate_iterator {
($iter:ty => $item:ty ,
impl $( $args:tt )*
) => {
impl $( $args )* ParallelIterator for $iter {
type Item = $item;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where C: UnindexedConsumer<Self::Item>
{
self.inner.drive_unindexed(consumer)
}
fn opt_len(&self) -> Option<usize> {
self.inner.opt_len()
}
}
}
}
/// Creates an indexed parallel iterator implementation which simply wraps an
/// inner type and delegates all methods inward. The actual struct must already
/// be declared with an `inner` field.
macro_rules! delegate_indexed_iterator {
($iter:ty => $item:ty ,
impl $( $args:tt )*
) => {
delegate_iterator!{
$iter => $item ,
impl $( $args )*
}
impl $( $args )* IndexedParallelIterator for $iter {
fn drive<C>(self, consumer: C) -> C::Result
where C: Consumer<Self::Item>
{
self.inner.drive(consumer)
}
fn len(&self) -> usize {
self.inner.len()
}
fn with_producer<CB>(self, callback: CB) -> CB::Output
where CB: ProducerCallback<Self::Item>
{
self.inner.with_producer(callback)
}
}
}
}
#[test]
fn unindexed_example() {
use crate::collections::btree_map::IntoIter;
use crate::iter::plumbing::*;
use crate::prelude::*;
use std::collections::BTreeMap;
struct MyIntoIter<T: Ord + Send, U: Send> {
inner: IntoIter<T, U>,
}
delegate_iterator! {
MyIntoIter<T, U> => (T, U),
impl<T: Ord + Send, U: Send>
}
let map = BTreeMap::from([(1, 'a'), (2, 'b'), (3, 'c')]);
let iter = MyIntoIter {
inner: map.into_par_iter(),
};
let vec: Vec<_> = iter.map(|(k, _)| k).collect();
assert_eq!(vec, &[1, 2, 3]);
}
#[test]
fn indexed_example() {
use crate::iter::plumbing::*;
use crate::prelude::*;
use crate::vec::IntoIter;
struct MyIntoIter<T: Send> {
inner: IntoIter<T>,
}
delegate_indexed_iterator! {
MyIntoIter<T> => T,
impl<T: Send>
}
let iter = MyIntoIter {
inner: vec![1, 2, 3].into_par_iter(),
};
let mut vec = vec![];
iter.collect_into_vec(&mut vec);
assert_eq!(vec, &[1, 2, 3]);
}
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