Struct im::vector::Vector

pub struct Vector<A> { /* fields omitted */ }

A persistent vector.

This is a sequence of elements in insertion order - if you need a list of things, any kind of list of things, this is what you're looking for.

It's implemented as an RRB vector with smart head/tail chunking. In performance terms, this means that practically every operation is O(log n), except push/pop on both sides, which will be O(1) amortised, and O(log n) in the worst case. In practice, the push/pop operations will be blindingly fast, nearly on par with the native VecDeque, and other operations will have decent, if not high, performance, but they all have more or less the same O(log n) complexity, so you don't need to keep their performance characteristics in mind - everything, even splitting and merging, is safe to use and never too slow.

Performance Notes

Because of the head/tail chunking technique, until you push a number of items above double the tree's branching factor (that's self.len() = 2 × k (where k = 64) = 128) on either side, the data structure is still just a handful of arrays, not yet an RRB tree, so you'll see performance and memory characteristics similar to Vec or VecDeque.

This means that the structure always preallocates four chunks of size k (k being the tree's branching factor), equivalent to a Vec with an initial capacity of 256. Beyond that, it will allocate tree nodes of capacity k as needed.

Methods

impl<A: Clone> Vector<A>

pub fn new() -> Self

Construct an empty vector.

pub fn singleton(a: A) -> Self

Construct a vector with a single value.

pub fn len(&self) -> usize

Get the length of a vector.

Time: O(1)

Examples

assert_eq!(5, vector![1, 2, 3, 4, 5].len());

pub fn is_empty(&self) -> bool

Test whether a vector is empty.

Time: O(1)

Examples

let vec = vector!["Joe", "Mike", "Robert"];
assert_eq!(false, vec.is_empty());
assert_eq!(true, Vector::<i32>::new().is_empty());

Important traits for Iter<'a, A>

impl<'a, A: Clone> Iterator for Iter<'a, A> type Item = &'a A;

pub fn iter(&self) -> Iter<A>

Get an iterator over a vector.

Time: O(1)

Important traits for IterMut<'a, A>

impl<'a, A: Clone> Iterator for IterMut<'a, A> type Item = &'a mut A;

pub fn iter_mut(&mut self) -> IterMut<A>

Get a mutable iterator over a vector.

Time: O(1)

pub fn get(&self, index: usize) -> Option<&A>

Get a reference to the value at index index in a vector.

Returns None if the index is out of bounds.

Time: O(log n)

Examples

let vec = vector!["Joe", "Mike", "Robert"];
assert_eq!(Some(&"Robert"), vec.get(2));
assert_eq!(None, vec.get(5));

pub fn get_mut(&mut self, index: usize) -> Option<&mut A>

Get a mutable reference to the value at index index in a vector.

Returns None if the index is out of bounds.

Time: O(log n)

Examples

let mut vec = vector!["Joe", "Mike", "Robert"];
{
    let robert = vec.get_mut(2).unwrap();
    assert_eq!(&mut "Robert", robert);
    *robert = "Bjarne";
}
assert_eq!(vector!["Joe", "Mike", "Bjarne"], vec);

pub fn front(&self) -> Option<&A>

Get the first element of a vector.

If the vector is empty, None is returned.

Time: O(log n)

pub fn front_mut(&mut self) -> Option<&mut A>

Get a mutable reference to the first element of a vector.

If the vector is empty, None is returned.

Time: O(log n)

pub fn head(&self) -> Option<&A>

Get the first element of a vector.

If the vector is empty, None is returned.

This is an alias for the front method.

Time: O(log n)

pub fn back(&self) -> Option<&A>

Get the last element of a vector.

If the vector is empty, None is returned.

Time: O(log n)

pub fn back_mut(&mut self) -> Option<&mut A>

Get a mutable reference to the last element of a vector.

If the vector is empty, None is returned.

Time: O(log n)

pub fn last(&self) -> Option<&A>

Get the last element of a vector.

If the vector is empty, None is returned.

This is an alias for the back method.

Time: O(log n)

pub fn index_of(&self, value: &A) -> Option<usize> where     A: PartialEq,

Get the index of a given element in the vector.

Searches the vector for the first occurrence of a given value, and returns the index of the value if it's there. Otherwise, it returns None.

Time: O(n)

Examples

let mut vec = vector![1, 2, 3, 4, 5];
assert_eq!(Some(2), vec.index_of(&3));
assert_eq!(None, vec.index_of(&31337));

pub fn contains(&self, value: &A) -> bool where     A: PartialEq,

Test if a given element is in the vector.

Searches the vector for the first occurrence of a given value, and returns true if it's there. If it's nowhere to be found in the vector, it returnsfalse`.

Time: O(n)

Examples

let mut vec = vector![1, 2, 3, 4, 5];
assert_eq!(true, vec.contains(&3));
assert_eq!(false, vec.contains(&31337));

pub fn update(&self, index: usize, value: A) -> Self

Create a new vector with the value at index index updated.

Panics if the index is out of bounds.

Time: O(log n)

Examples

let mut vec = vector![1, 2, 3];
assert_eq!(vector![1, 5, 3], vec.update(1, 5));

pub fn set(&mut self, index: usize, value: A)

Update the value at index index in a vector.

Panics if the index is out of bounds.

Time: O(log n)

pub fn swap(&mut self, i: usize, j: usize)

Swaps the elements at indices i and j.

Time: O(log n)

pub fn push_front(&mut self, value: A)

Push a value to the front of a vector.

Time: O(1)*

Examples

let mut vec = vector![5, 6, 7];
vec.push_front(4);
assert_eq!(vector![4, 5, 6, 7], vec);

pub fn push_back(&mut self, value: A)

Push a value to the back of a vector.

Time: O(1)*

Examples

let mut vec = vector![1, 2, 3];
vec.push_back(4);
assert_eq!(vector![1, 2, 3, 4], vec);

pub fn pop_front(&mut self) -> Option<A>

Remove the first element from a vector and return it.

Time: O(1)*

Examples

let mut vec = vector![1, 2, 3];
assert_eq!(Some(1), vec.pop_front());
assert_eq!(vector![2, 3], vec);

pub fn pop_back(&mut self) -> Option<A>

Remove the last element from a vector and return it.

Time: O(1)*

Examples

let mut vec = vector![1, 2, 3];
assert_eq!(Some(3), vec.pop_back());
assert_eq!(vector![1, 2], vec);

pub fn append(&mut self, other: Self)

Append the vector other to the end of the current vector.

Time: O(log n)

Examples

let mut vec = vector![1, 2, 3];
vec.append(vector![7, 8, 9]);
assert_eq!(vector![1, 2, 3, 7, 8, 9], vec);

pub fn retain<F>(&mut self, f: F) where     F: FnMut(&A) -> bool,

Retain only the elements specified by the predicate.

Remove all elements for which the provided function f returns false from the vector.

Time: O(n)

pub fn split_at(self, index: usize) -> (Self, Self)

Split a vector at a given index.

Split a vector at a given index, consuming the vector and returning a pair of the left hand side and the right hand side of the split.

Time: O(log n)

Examples

let mut vec = vector![1, 2, 3, 7, 8, 9];
let (left, right) = vec.split_at(3);
assert_eq!(vector![1, 2, 3], left);
assert_eq!(vector![7, 8, 9], right);

pub fn split_off(&mut self, index: usize) -> Self

Split a vector at a given index.

Split a vector at a given index, leaving the left hand side in the current vector and returning a new vector containing the right hand side.

Time: O(log n)

Examples

let mut left = vector![1, 2, 3, 7, 8, 9];
let right = left.split_off(3);
assert_eq!(vector![1, 2, 3], left);
assert_eq!(vector![7, 8, 9], right);

pub fn skip(&self, count: usize) -> Self

Construct a vector with count elements removed from the start of the current vector.

Time: O(log n)

pub fn take(&self, count: usize) -> Self

Construct a vector of the first count elements from the current vector.

Time: O(log n)

pub fn truncate(&mut self, len: usize)

Truncate a vector to the given size.

Discards all elements in the vector beyond the given length.

Panics if the new length is greater than the current length.

Time: O(log n)

pub fn insert(&mut self, index: usize, value: A)

Insert an element into a vector.

Insert an element at position index, shifting all elements after it to the right.

Performance Note

While push_front and push_back are heavily optimised operations, insert in the middle of a vector requires a split, a push, and an append. Thus, if you want to insert many elements at the same location, instead of inserting them one by one, you should rather create a new vector containing the elements to insert, split the vector at the insertion point, and append the left hand, the new vector and the right hand in order.

Time: O(log n)

pub fn remove(&mut self, index: usize) -> A

Remove an element from a vector.

Remove the element from position 'index', shifting all elements after it to the left, and return the removec element.

Performance Note

While pop_front and pop_back are heavily optimised operations, remove in the middle of a vector requires a split, a pop, and an append. Thus, if you want to remove many elements from the same location, instead of removeing them one by one, it is much better to use slice.

Time: O(log n)

pub fn clear(&mut self)

Discard all elements from the vector.

This leaves you with an empty vector, and all elements that were previously inside it are dropped.

Time: O(n)

pub fn binary_search_by<F>(&self, f: F) -> Result<usize, usize> where     F: FnMut(&A) -> Ordering,

Binary search a sorted vector for a given element using a comparator function.

Assumes the vector has already been sorted using the same comparator function, eg. by using sort_by.

If the value is found, it returns Ok(index) where index is the index of the element. If the value isn't found, it returns Err(index) where index is the index at which the element would need to be inserted to maintain sorted order.

Time: O(log n)

pub fn binary_search(&self, value: &A) -> Result<usize, usize> where     A: Ord,

Binary search a sorted vector for a given element.

If the value is found, it returns Ok(index) where index is the index of the element. If the value isn't found, it returns Err(index) where index is the index at which the element would need to be inserted to maintain sorted order.

Time: O(log n)

pub fn binary_search_by_key<B, F>(&self, b: &B, f: F) -> Result<usize, usize> where     F: FnMut(&A) -> B,     B: Ord,

Binary search a sorted vector for a given element with a key extract function.

Assumes the vector has already been sorted using the same key extract function, eg. by using sort_by_key.

If the value is found, it returns Ok(index) where index is the index of the element. If the value isn't found, it returns Err(index) where index is the index at which the element would need to be inserted to maintain sorted order.

Time: O(log n)

pub fn insert_ord(&mut self, item: A) where     A: Ord,

Insert an element into a sorted vector.

Insert an element into a vector in sorted order, assuming the vector is already in sorted order.

Time: O(log n)

Examples

let mut vec = vector![1, 2, 3, 7, 8, 9];
vec.insert_ord(5);
assert_eq!(vector![1, 2, 3, 5, 7, 8, 9], vec);

pub fn sort(&mut self) where     A: Ord,

Sort a vector.

Time: O(n log n)

Examples

let mut vec = vector![3, 2, 5, 4, 1];
vec.sort();
assert_eq!(vector![1, 2, 3, 4, 5], vec);

pub fn sort_by<F>(&mut self, cmp: F) where     F: Fn(&A, &A) -> Ordering,

Sort a vector using a comparator function.

Time: O(n log n)

Examples

let mut vec = vector![3, 2, 5, 4, 1];
vec.sort_by(|left, right| left.cmp(right));
assert_eq!(vector![1, 2, 3, 4, 5], vec);

Trait Implementations

impl<A: Clone> Default for Vector<A>

fn default() -> Self

Returns the "default value" for a type.

impl<A> Clone for Vector<A>

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<A: Clone + Debug> Debug for Vector<A>

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl<A: Clone + PartialEq> PartialEq for Vector<A>

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl<A: Clone + Eq> Eq for Vector<A>

impl<A: Clone + PartialOrd> PartialOrd for Vector<A>

fn partial_cmp(&self, other: &Self) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl<A: Clone + Ord> Ord for Vector<A>

fn cmp(&self, other: &Self) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

impl<A: Clone + Hash> Hash for Vector<A>

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given [Hasher].

fn hash_slice<H>(data: &[Self], state: &mut H) where     H: Hasher,

Feeds a slice of this type into the given [Hasher].

impl<A: Clone> Sum for Vector<A>

fn sum<I>(it: I) -> Self where     I: Iterator<Item = Self>,

Method which takes an iterator and generates Self from the elements by "summing up" the items.

impl<A: Clone> Add for Vector<A>

type Output = Vector<A>

The resulting type after applying the + operator.

fn add(self, other: Self) -> Self::Output

Concatenate two vectors.

Time: O(log n)

impl<'a, A: Clone> Add for &'a Vector<A>

type Output = Vector<A>

The resulting type after applying the + operator.

fn add(self, other: Self) -> Self::Output

Concatenate two vectors.

Time: O(log n)

impl<A: Clone> Extend<A> for Vector<A>

fn extend<I>(&mut self, iter: I) where     I: IntoIterator<Item = A>,

Add values to the end of a vector by consuming an iterator.

Time: O(n)

impl<A: Clone> Index<usize> for Vector<A>

type Output = A

The returned type after indexing.

fn index(&self, index: usize) -> &Self::Output

Get a reference to the value at index index in the vector.

Time: O(log n)

impl<A: Clone> IndexMut<usize> for Vector<A>

fn index_mut(&mut self, index: usize) -> &mut Self::Output

Get a mutable reference to the value at index index in the vector.

Time: O(log n)

impl<'a, A: Clone> IntoIterator for &'a Vector<A>

type Item = &'a A

The type of the elements being iterated over.

type IntoIter = Iter<'a, A>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<A: Clone> IntoIterator for Vector<A>

type Item = A

The type of the elements being iterated over.

type IntoIter = ConsumingIter<A>

Which kind of iterator are we turning this into?

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

impl<A: Clone> FromIterator<A> for Vector<A>

fn from_iter<I>(iter: I) -> Self where     I: IntoIterator<Item = A>,

Create a vector from an iterator.

Time: O(n)

impl<'s, 'a, A, OA> From<&'s Vector<&'a A>> for Vector<OA> where     A: ToOwned<Owned = OA>,     OA: Borrow<A> + Clone,

fn from(vec: &Vector<&A>) -> Self

Performs the conversion.

impl<'a, A: Clone> From<&'a [A]> for Vector<A>

fn from(slice: &[A]) -> Self

Performs the conversion.

impl<A: Clone> From<Vec<A>> for Vector<A>

fn from(vec: Vec<A>) -> Self

Create a vector from a std::vec::Vec.

Time: O(n)

impl<'a, A: Clone> From<&'a Vec<A>> for Vector<A>

fn from(vec: &Vec<A>) -> Self

Create a vector from a std::vec::Vec.

Time: O(n)