Struct indextree::Arena

pub struct Arena<T> { /* fields omitted */ }

An Arena structure containing certain Nodes.

Implementations

impl<T> Arena<T>

pub fn new() -> Arena<T>

Creates a new empty Arena.

pub fn get_node_id(&self, node: &Node<T>) -> Option<NodeId> where
    T: PartialEq, 

Retrieves the NodeId correspoding to a Node in the Arena. Note that this method can only be used if the datatype of the Node implements the PartialEq trait.

pub fn new_node(&mut self, data: T) -> NodeId

Creates a new node from its associated data.

Panics

Panics if the arena already has usize::max_value() nodes.

Examples

let mut arena = Arena::new();
let foo = arena.new_node("foo");

assert_eq!(*arena[foo].get(), "foo");

pub fn count(&self) -> usize

Counts the number of nodes in arena and returns it.

Examples

let mut arena = Arena::new();
let foo = arena.new_node("foo");
let _bar = arena.new_node("bar");
assert_eq!(arena.count(), 2);

foo.remove(&mut arena);
assert_eq!(arena.count(), 2);

pub fn is_empty(&self) -> bool

Returns true if arena has no nodes, false otherwise.

Examples

let mut arena = Arena::new();
assert!(arena.is_empty());

let foo = arena.new_node("foo");
assert!(!arena.is_empty());

foo.remove(&mut arena);
assert!(!arena.is_empty());

pub fn get(&self, id: NodeId) -> Option<&Node<T>>

Returns a reference to the node with the given id if in the arena.

Returns None if not available.

Examples

let mut arena = Arena::new();
let foo = arena.new_node("foo");
assert_eq!(arena.get(foo).map(|node| *node.get()), Some("foo"));

Note that this does not check whether the given node ID is created by the arena.

let mut arena = Arena::new();
let foo = arena.new_node("foo");
let bar = arena.new_node("bar");
assert_eq!(arena.get(foo).map(|node| *node.get()), Some("foo"));

let mut another_arena = Arena::new();
let _ = another_arena.new_node("Another arena");
assert_eq!(another_arena.get(foo).map(|node| *node.get()), Some("Another arena"));
assert!(another_arena.get(bar).is_none());

pub fn get_mut(&mut self, id: NodeId) -> Option<&mut Node<T>>

Returns a mutable reference to the node with the given id if in the arena.

Returns None if not available.

Examples

let mut arena = Arena::new();
let foo = arena.new_node("foo");
assert_eq!(arena.get(foo).map(|node| *node.get()), Some("foo"));

*arena.get_mut(foo).expect("The `foo` node exists").get_mut() = "FOO!";
assert_eq!(arena.get(foo).map(|node| *node.get()), Some("FOO!"));

pub fn iter(&self) -> impl Iterator<Item = &Node<T>>

Returns an iterator of all nodes in the arena in storage-order.

Note that this iterator returns also removed elements, which can be tested with the is_removed() method on the node.

Examples

let mut arena = Arena::new();
let _foo = arena.new_node("foo");
let _bar = arena.new_node("bar");

let mut iter = arena.iter();
assert_eq!(iter.next().map(|node| *node.get()), Some("foo"));
assert_eq!(iter.next().map(|node| *node.get()), Some("bar"));
assert_eq!(iter.next().map(|node| *node.get()), None);

let mut arena = Arena::new();
let _foo = arena.new_node("foo");
let bar = arena.new_node("bar");
bar.remove(&mut arena);

let mut iter = arena.iter();
assert_eq!(iter.next().map(|node| (*node.get(), node.is_removed())), Some(("foo", false)));
assert_eq!(iter.next().map(|node| (*node.get(), node.is_removed())), Some(("bar", true)));
assert_eq!(iter.next().map(|node| (*node.get(), node.is_removed())), None);

Trait Implementations

impl<T: Clone> Clone for Arena<T>

fn clone(&self) -> Arena<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for Arena<T>

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

Formats the value using the given formatter.

impl<T> Default for Arena<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T: Eq> Eq for Arena<T>

impl<T> Index<NodeId> for Arena<T>

type Output = Node<T>

The returned type after indexing.

fn index(&self, node: NodeId) -> &Node<T>

Performs the indexing (container[index]) operation.

impl<T> IndexMut<NodeId> for Arena<T>

fn index_mut(&mut self, node: NodeId) -> &mut Node<T>

Performs the mutable indexing (container[index]) operation.

impl<T: PartialEq> PartialEq<Arena<T>> for Arena<T>

fn eq(&self, other: &Arena<T>) -> bool

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

fn ne(&self, other: &Arena<T>) -> bool

This method tests for !=.

impl<T> StructuralEq for Arena<T>

impl<T> StructuralPartialEq for Arena<T>