Struct linked_hash_set::LinkedHashSet
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pub struct LinkedHashSet<T, S = RandomState> { /* fields omitted */ }
A linked hash set implemented as a linked_hash_map::LinkedHashMap
where the value is
()
, in a similar way std HashSet
is implemented from HashMap
.
General usage is very similar to a std HashSet
. However, a LinkedHashSet
maintains
insertion order using a doubly-linked list running through its entries. As such methods
front()
, pop_front()
, back()
and pop_back()
are provided.
Examples
use linked_hash_set::LinkedHashSet; // Type inference lets us omit an explicit type signature (which // would be `LinkedHashSet<&str>` in this example). let mut books = LinkedHashSet::new(); // Add some books. books.insert("A Dance With Dragons"); books.insert("To Kill a Mockingbird"); books.insert("The Odyssey"); books.insert("The Great Gatsby"); // Check for a specific one. if !books.contains("The Winds of Winter") { println!( "We have {} books, but The Winds of Winter ain't one.", books.len() ); } // Remove a book. books.remove("The Odyssey"); // Remove the first inserted book. books.pop_front(); // Iterate over the remaining books in insertion order. for book in &books { println!("{}", book); } assert_eq!( books.into_iter().collect::<Vec<_>>(), vec!["To Kill a Mockingbird", "The Great Gatsby"] );
The easiest way to use LinkedHashSet
with a custom type is to derive
Eq
and Hash
. We must also derive PartialEq
, this will in the
future be implied by Eq
.
use linked_hash_set::LinkedHashSet; #[derive(Hash, Eq, PartialEq, Debug)] struct Viking<'a> { name: &'a str, power: usize, } let mut vikings = LinkedHashSet::new(); vikings.insert(Viking { name: "Einar", power: 9 }); vikings.insert(Viking { name: "Einar", power: 9 }); vikings.insert(Viking { name: "Olaf", power: 4 }); vikings.insert(Viking { name: "Harald", power: 8 }); // Use derived implementation to print the vikings. for x in &vikings { println!("{:?}", x); }
A LinkedHashSet
with fixed list of elements can be initialized from an array:
use linked_hash_set::LinkedHashSet; fn main() { let viking_names: LinkedHashSet<&str> = [ "Einar", "Olaf", "Harald" ].iter().cloned().collect(); // use the values stored in the set }
Methods
impl<T: Hash + Eq> LinkedHashSet<T, RandomState>
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fn new() -> LinkedHashSet<T, RandomState>
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Creates an empty LinkedHashSet
.
Examples
use linked_hash_set::LinkedHashSet; let set: LinkedHashSet<i32> = LinkedHashSet::new();
fn with_capacity(capacity: usize) -> LinkedHashSet<T, RandomState>
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Creates an empty LinkedHashSet
with the specified capacity.
The hash set will be able to hold at least capacity
elements without
reallocating. If capacity
is 0, the hash set will not allocate.
Examples
use linked_hash_set::LinkedHashSet; let set: LinkedHashSet<i32> = LinkedHashSet::with_capacity(10); assert!(set.capacity() >= 10);
impl<T, S> LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher,
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T: Eq + Hash,
S: BuildHasher,
fn with_hasher(hasher: S) -> LinkedHashSet<T, S>
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Creates a new empty hash set which will use the given hasher to hash keys.
The hash set is also created with the default initial capacity.
Warning: hasher
is normally randomly generated, and
is designed to allow LinkedHashSet
s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.
Examples
use linked_hash_set::LinkedHashSet; use std::collections::hash_map::RandomState; let s = RandomState::new(); let mut set = LinkedHashSet::with_hasher(s); set.insert(2);
fn with_capacity_and_hasher(capacity: usize, hasher: S) -> LinkedHashSet<T, S>
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Creates an empty LinkedHashSet
with with the specified capacity, using
hasher
to hash the keys.
The hash set will be able to hold at least capacity
elements without
reallocating. If capacity
is 0, the hash set will not allocate.
Warning: hasher
is normally randomly generated, and
is designed to allow LinkedHashSet
s to be resistant to attacks that
cause many collisions and very poor performance. Setting it
manually using this function can expose a DoS attack vector.
Examples
use linked_hash_set::LinkedHashSet; use std::collections::hash_map::RandomState; let s = RandomState::new(); let mut set = LinkedHashSet::with_capacity_and_hasher(10, s); set.insert(1);
fn hasher(&self) -> &S
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Returns a reference to the set's BuildHasher
.
Examples
use linked_hash_set::LinkedHashSet; use std::collections::hash_map::RandomState; let hasher = RandomState::new(); let set: LinkedHashSet<i32> = LinkedHashSet::with_hasher(hasher); let hasher: &RandomState = set.hasher();
fn capacity(&self) -> usize
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Returns the number of elements the set can hold without reallocating.
Examples
use linked_hash_set::LinkedHashSet; let set: LinkedHashSet<i32> = LinkedHashSet::with_capacity(100); assert!(set.capacity() >= 100);
fn reserve(&mut self, additional: usize)
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Reserves capacity for at least additional
more elements to be inserted
in the LinkedHashSet
. The collection may reserve more space to avoid
frequent reallocations.
Panics
Panics if the new allocation size overflows usize
.
Examples
use linked_hash_set::LinkedHashSet; let mut set: LinkedHashSet<i32> = LinkedHashSet::new(); set.reserve(10); assert!(set.capacity() >= 10);
fn shrink_to_fit(&mut self)
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Shrinks the capacity of the set as much as possible. It will drop down as much as possible while maintaining the internal rules and possibly leaving some space in accordance with the resize policy.
Examples
use linked_hash_set::LinkedHashSet; let mut set = LinkedHashSet::with_capacity(100); set.insert(1); set.insert(2); assert!(set.capacity() >= 100); set.shrink_to_fit(); assert!(set.capacity() >= 2);
fn iter(&self) -> Iter<T>
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An iterator visiting all elements in insertion order.
The iterator element type is &'a T
.
Examples
use linked_hash_set::LinkedHashSet; let mut set = LinkedHashSet::new(); set.insert("a"); set.insert("b"); // Will print in an insertion order. for x in set.iter() { println!("{}", x); }
fn difference<'a>(
&'a self,
other: &'a LinkedHashSet<T, S>
) -> Difference<'a, T, S>
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&'a self,
other: &'a LinkedHashSet<T, S>
) -> Difference<'a, T, S>
Visits the values representing the difference,
i.e. the values that are in self
but not in other
.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let b: LinkedHashSet<_> = [4, 2, 3, 4].iter().cloned().collect(); // Can be seen as `a - b`. for x in a.difference(&b) { println!("{}", x); // Print 1 } let diff: LinkedHashSet<_> = a.difference(&b).collect(); assert_eq!(diff, [1].iter().collect()); // Note that difference is not symmetric, // and `b - a` means something else: let diff: LinkedHashSet<_> = b.difference(&a).collect(); assert_eq!(diff, [4].iter().collect());
fn symmetric_difference<'a>(
&'a self,
other: &'a LinkedHashSet<T, S>
) -> SymmetricDifference<'a, T, S>
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&'a self,
other: &'a LinkedHashSet<T, S>
) -> SymmetricDifference<'a, T, S>
Visits the values representing the symmetric difference,
i.e. the values that are in self
or in other
but not in both.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let b: LinkedHashSet<_> = [4, 2, 3, 4].iter().cloned().collect(); // Print 1, 4 in insertion order. for x in a.symmetric_difference(&b) { println!("{}", x); } let diff1: LinkedHashSet<_> = a.symmetric_difference(&b).collect(); let diff2: LinkedHashSet<_> = b.symmetric_difference(&a).collect(); assert_eq!(diff1, diff2); assert_eq!(diff1, [1, 4].iter().collect());
fn intersection<'a>(
&'a self,
other: &'a LinkedHashSet<T, S>
) -> Intersection<'a, T, S>
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&'a self,
other: &'a LinkedHashSet<T, S>
) -> Intersection<'a, T, S>
Visits the values representing the intersection,
i.e. the values that are both in self
and other
.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let b: LinkedHashSet<_> = [4, 2, 3, 4].iter().cloned().collect(); // Print 2, 3 in insertion order. for x in a.intersection(&b) { println!("{}", x); } let intersection: LinkedHashSet<_> = a.intersection(&b).collect(); assert_eq!(intersection, [2, 3].iter().collect());
fn union<'a>(&'a self, other: &'a LinkedHashSet<T, S>) -> Union<'a, T, S>
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Visits the values representing the union,
i.e. all the values in self
or other
, without duplicates.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let b: LinkedHashSet<_> = [4, 2, 3, 4].iter().cloned().collect(); // Print 1, 2, 3, 4 in insertion order. for x in a.union(&b) { println!("{}", x); } let union: LinkedHashSet<_> = a.union(&b).collect(); assert_eq!(union, [1, 2, 3, 4].iter().collect());
fn len(&self) -> usize
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Returns the number of elements in the set.
Examples
use linked_hash_set::LinkedHashSet; let mut v = LinkedHashSet::new(); assert_eq!(v.len(), 0); v.insert(1); assert_eq!(v.len(), 1);
fn is_empty(&self) -> bool
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Returns true if the set contains no elements.
Examples
use linked_hash_set::LinkedHashSet; let mut v = LinkedHashSet::new(); assert!(v.is_empty()); v.insert(1); assert!(!v.is_empty());
fn clear(&mut self)
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Clears the set, removing all values.
Examples
use linked_hash_set::LinkedHashSet; let mut v = LinkedHashSet::new(); v.insert(1); v.clear(); assert!(v.is_empty());
fn contains<Q: ?Sized>(&self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
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T: Borrow<Q>,
Q: Hash + Eq,
Returns true
if the set contains a value.
The value may be any borrowed form of the set's value type, but
Hash
and Eq
on the borrowed form must match those for
the value type.
Examples
use linked_hash_set::LinkedHashSet; let set: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); assert_eq!(set.contains(&1), true); assert_eq!(set.contains(&4), false);
fn refresh<Q: ?Sized>(&mut self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
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T: Borrow<Q>,
Q: Hash + Eq,
If already present, moves a value to the end of the ordering.
If the set did have this value present, true
is returned.
If the set did not have this value present, false
is returned.
Similar to LinkedHashMap::get_refresh
.
Examples
use linked_hash_set::LinkedHashSet; let mut set: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let was_refreshed = set.refresh(&2); assert_eq!(was_refreshed, true); assert_eq!(set.into_iter().collect::<Vec<_>>(), vec![1, 3, 2]);
fn is_disjoint(&self, other: &LinkedHashSet<T, S>) -> bool
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Returns true
if self
has no elements in common with other
.
This is equivalent to checking for an empty intersection.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let mut b = LinkedHashSet::new(); assert_eq!(a.is_disjoint(&b), true); b.insert(4); assert_eq!(a.is_disjoint(&b), true); b.insert(1); assert_eq!(a.is_disjoint(&b), false);
fn is_subset(&self, other: &LinkedHashSet<T, S>) -> bool
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Returns true
if the set is a subset of another,
i.e. other
contains at least all the values in self
.
Examples
use linked_hash_set::LinkedHashSet; let sup: LinkedHashSet<_> = [1, 2, 3].iter().cloned().collect(); let mut set = LinkedHashSet::new(); assert_eq!(set.is_subset(&sup), true); set.insert(2); assert_eq!(set.is_subset(&sup), true); set.insert(4); assert_eq!(set.is_subset(&sup), false);
fn is_superset(&self, other: &LinkedHashSet<T, S>) -> bool
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Returns true
if the set is a superset of another,
i.e. self
contains at least all the values in other
.
Examples
use linked_hash_set::LinkedHashSet; let sub: LinkedHashSet<_> = [1, 2].iter().cloned().collect(); let mut set = LinkedHashSet::new(); assert_eq!(set.is_superset(&sub), false); set.insert(0); set.insert(1); assert_eq!(set.is_superset(&sub), false); set.insert(2); assert_eq!(set.is_superset(&sub), true);
fn insert(&mut self, value: T) -> bool
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Adds a value to the set.
If the set did not have this value present, true
is returned.
If the set did have this value present, false
is returned.
Note that performing this action will always place the value at the end of the ordering
whether the set already contained the value or not. Also see
insert_if_absent
.
Examples
use linked_hash_set::LinkedHashSet; let mut set = LinkedHashSet::new(); assert_eq!(set.insert(2), true); assert_eq!(set.insert(2), false); assert_eq!(set.len(), 1);
fn insert_if_absent(&mut self, value: T) -> bool
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Adds a value to the set, if not already present. The distinction with insert
is that
order of elements is unaffected when calling this method for a value already contained.
If the set did not have this value present, true
is returned.
If the set did have this value present, false
is returned.
Examples
use linked_hash_set::LinkedHashSet; let mut set = LinkedHashSet::new(); assert_eq!(set.insert_if_absent(2), true); assert_eq!(set.insert_if_absent(2), false); assert_eq!(set.len(), 1);
fn remove<Q: ?Sized>(&mut self, value: &Q) -> bool where
T: Borrow<Q>,
Q: Hash + Eq,
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T: Borrow<Q>,
Q: Hash + Eq,
Removes a value from the set. Returns true
if the value was
present in the set.
The value may be any borrowed form of the set's value type, but
Hash
and Eq
on the borrowed form must match those for
the value type.
This operation will not affect the ordering of the other elements.
Examples
use linked_hash_set::LinkedHashSet; let mut set = LinkedHashSet::new(); set.insert(2); assert_eq!(set.remove(&2), true); assert_eq!(set.remove(&2), false);
fn front(&self) -> Option<&T>
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Gets the first entry.
fn pop_front(&mut self) -> Option<T>
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Removes the first entry.
fn back(&mut self) -> Option<&T>
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Gets the last entry.
fn pop_back(&mut self) -> Option<T>
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Removes the last entry.
Trait Implementations
impl<T: Hash + Eq + Clone, S: BuildHasher + Clone> Clone for LinkedHashSet<T, S>
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fn clone(&self) -> Self
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Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
1.0.0[src]
Performs copy-assignment from source
. Read more
impl<T, S> PartialEq for LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher,
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T: Eq + Hash,
S: BuildHasher,
fn eq(&self, other: &LinkedHashSet<T, S>) -> bool
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This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
1.0.0[src]
This method tests for !=
.
impl<T, S> Eq for LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher,
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T: Eq + Hash,
S: BuildHasher,
impl<T, S> Debug for LinkedHashSet<T, S> where
T: Eq + Hash + Debug,
S: BuildHasher,
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T: Eq + Hash + Debug,
S: BuildHasher,
impl<T, S> FromIterator<T> for LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher + Default,
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T: Eq + Hash,
S: BuildHasher + Default,
fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> LinkedHashSet<T, S>
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Creates a value from an iterator. Read more
impl<T, S> Extend<T> for LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher,
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T: Eq + Hash,
S: BuildHasher,
fn extend<I: IntoIterator<Item = T>>(&mut self, iter: I)
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Extends a collection with the contents of an iterator. Read more
impl<'a, T, S> Extend<&'a T> for LinkedHashSet<T, S> where
T: 'a + Eq + Hash + Copy,
S: BuildHasher,
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T: 'a + Eq + Hash + Copy,
S: BuildHasher,
fn extend<I: IntoIterator<Item = &'a T>>(&mut self, iter: I)
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Extends a collection with the contents of an iterator. Read more
impl<T, S> Default for LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher + Default,
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T: Eq + Hash,
S: BuildHasher + Default,
fn default() -> LinkedHashSet<T, S>
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Creates an empty LinkedHashSet<T, S>
with the Default
value for the hasher.
impl<'a, 'b, T, S> BitOr<&'b LinkedHashSet<T, S>> for &'a LinkedHashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
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T: Eq + Hash + Clone,
S: BuildHasher + Default,
type Output = LinkedHashSet<T, S>
The resulting type after applying the |
operator.
fn bitor(self, rhs: &LinkedHashSet<T, S>) -> LinkedHashSet<T, S>
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Returns the union of self
and rhs
as a new LinkedHashSet<T, S>
.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = vec![1, 2, 3].into_iter().collect(); let b: LinkedHashSet<_> = vec![3, 4, 5].into_iter().collect(); let set = &a | &b; let mut i = 0; let expected = [1, 2, 3, 4, 5]; for x in &set { assert!(expected.contains(x)); i += 1; } assert_eq!(i, expected.len());
impl<'a, 'b, T, S> BitAnd<&'b LinkedHashSet<T, S>> for &'a LinkedHashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
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T: Eq + Hash + Clone,
S: BuildHasher + Default,
type Output = LinkedHashSet<T, S>
The resulting type after applying the &
operator.
fn bitand(self, rhs: &LinkedHashSet<T, S>) -> LinkedHashSet<T, S>
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Returns the intersection of self
and rhs
as a new LinkedHashSet<T, S>
.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = vec![1, 2, 3].into_iter().collect(); let b: LinkedHashSet<_> = vec![2, 3, 4].into_iter().collect(); let set = &a & &b; let mut i = 0; let expected = [2, 3]; for x in &set { assert!(expected.contains(x)); i += 1; } assert_eq!(i, expected.len());
impl<'a, 'b, T, S> BitXor<&'b LinkedHashSet<T, S>> for &'a LinkedHashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
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T: Eq + Hash + Clone,
S: BuildHasher + Default,
type Output = LinkedHashSet<T, S>
The resulting type after applying the ^
operator.
fn bitxor(self, rhs: &LinkedHashSet<T, S>) -> LinkedHashSet<T, S>
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Returns the symmetric difference of self
and rhs
as a new LinkedHashSet<T, S>
.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = vec![1, 2, 3].into_iter().collect(); let b: LinkedHashSet<_> = vec![3, 4, 5].into_iter().collect(); let set = &a ^ &b; let mut i = 0; let expected = [1, 2, 4, 5]; for x in &set { assert!(expected.contains(x)); i += 1; } assert_eq!(i, expected.len());
impl<'a, 'b, T, S> Sub<&'b LinkedHashSet<T, S>> for &'a LinkedHashSet<T, S> where
T: Eq + Hash + Clone,
S: BuildHasher + Default,
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T: Eq + Hash + Clone,
S: BuildHasher + Default,
type Output = LinkedHashSet<T, S>
The resulting type after applying the -
operator.
fn sub(self, rhs: &LinkedHashSet<T, S>) -> LinkedHashSet<T, S>
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Returns the difference of self
and rhs
as a new LinkedHashSet<T, S>
.
Examples
use linked_hash_set::LinkedHashSet; let a: LinkedHashSet<_> = vec![1, 2, 3].into_iter().collect(); let b: LinkedHashSet<_> = vec![3, 4, 5].into_iter().collect(); let set = &a - &b; let mut i = 0; let expected = [1, 2]; for x in &set { assert!(expected.contains(x)); i += 1; } assert_eq!(i, expected.len());
impl<'a, T, S> IntoIterator for &'a LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher,
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T: Eq + Hash,
S: BuildHasher,
type Item = &'a T
The type of the elements being iterated over.
type IntoIter = Iter<'a, T>
Which kind of iterator are we turning this into?
fn into_iter(self) -> Iter<'a, T>
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Creates an iterator from a value. Read more
impl<T, S> IntoIterator for LinkedHashSet<T, S> where
T: Eq + Hash,
S: BuildHasher,
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T: Eq + Hash,
S: BuildHasher,
type Item = T
The type of the elements being iterated over.
type IntoIter = IntoIter<T>
Which kind of iterator are we turning this into?
fn into_iter(self) -> IntoIter<T>
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Creates a consuming iterator, that is, one that moves each value out of the set in insertion order. The set cannot be used after calling this.
Examples
use linked_hash_set::LinkedHashSet; let mut set = LinkedHashSet::new(); set.insert("a".to_string()); set.insert("b".to_string()); // Not possible to collect to a Vec<String> with a regular `.iter()`. let v: Vec<String> = set.into_iter().collect(); // Will print in an insertion order. for x in &v { println!("{}", x); }