collect_with

Trait CollectIndex

Source 
pub trait CollectIndex: Iterator {
    // Provided methods
    fn collect_indexmap_with<K, V>(
        self,
        capacity: impl FnOnce(usize) -> usize,
    ) -> IndexMap<K, V, RandomState>
       where Self: Sized + Iterator<Item = (K, V)>,
             K: Hash + Eq { ... }
    fn collect_indexmap_with_exact<K, V>(
        self,
        capacity: impl FnOnce(usize) -> usize,
    ) -> IndexMap<K, V>
       where Self: Sized + Iterator<Item = (K, V)>,
             K: Hash + Eq { ... }
    fn collect_indexset_with<K>(
        self,
        capacity: impl FnOnce(usize) -> usize,
    ) -> IndexSet<K, RandomState>
       where Self: Sized + Iterator<Item = K>,
             K: Hash + Eq { ... }
    fn collect_indexset_with_exact<K>(
        self,
        capacity: impl FnOnce(usize) -> usize,
    ) -> IndexSet<K>
       where Self: Sized + Iterator<Item = K>,
             K: Hash + Eq { ... }
}
Available on crate feature indexmap only.
Expand description

Trait for collecting items into IndexMap or IndexSet with specified capacity while preserving insertion order.

Provided Methods§

Source

fn collect_indexmap_with<K, V>( self, capacity: impl FnOnce(usize) -> usize, ) -> IndexMap<K, V, RandomState>
where Self: Sized + Iterator<Item = (K, V)>, K: Hash + Eq,

Available on crate feature ahash only.

Collects items into an IndexMap<K, V, ahash::RandomState> with a specified capacity.

§Example
use indexmap::IndexMap;
use collect_with::CollectIndex;

let map = ('a'..='i')
  .zip(100..=109)
  .collect_indexmap_with(|u| u + 1); // u + 1 => 9 + 1 = 10

assert_eq!(map.get(&'a'), Some(&100));
assert_eq!(map.get_index(0), Some((&'a', &100)));
assert_eq!(map.get_index(2), Some((&'c', &102)));
assert_eq!(map.capacity(), 10);
Source

fn collect_indexmap_with_exact<K, V>( self, capacity: impl FnOnce(usize) -> usize, ) -> IndexMap<K, V>
where Self: Sized + Iterator<Item = (K, V)>, K: Hash + Eq,

Collects items into an IndexMap with exact specified capacity.

Preserves insertion order and strictly uses calculated capacity.

§Example
use indexmap::IndexMap;
use collect_with::CollectIndex;

let map = [(1, "a"), (2, "b"), (3, "c")]
    .into_iter()
    .collect_indexmap_with_exact(|size_hint| size_hint);
assert_eq!(map.len(), 3);
assert_eq!(map.capacity(), 3);
Source

fn collect_indexset_with<K>( self, capacity: impl FnOnce(usize) -> usize, ) -> IndexSet<K, RandomState>
where Self: Sized + Iterator<Item = K>, K: Hash + Eq,

Available on crate feature ahash only.

Collects items into an IndexSet<K, ahash::RandomState> with specified capacity.

Preserves insertion order and maintains unique elements.

§Example
use indexmap::IndexSet;
use collect_with::CollectIndex;

let set = (0..3)
    .collect_indexset_with(|size_hint| size_hint + 2);
assert_eq!(set.len(), 3);
assert!(set.capacity() >= 3);
Source

fn collect_indexset_with_exact<K>( self, capacity: impl FnOnce(usize) -> usize, ) -> IndexSet<K>
where Self: Sized + Iterator<Item = K>, K: Hash + Eq,

Collects items into an IndexSet with exact specified capacity.

Preserves insertion order and strictly uses calculated capacity.

§Example
use indexmap::IndexSet;
use collect_with::CollectIndex;

let set = (0..3)
    .into_iter()
    .collect_indexset_with_exact(|size_hint| size_hint);
assert_eq!(set.len(), 3);
assert_eq!(set.capacity(), 3);

Implementors§