Struct internment::Intern

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

A pointer to an interned object.

The interned object will be held in memory indefinitely. On the plus side, this means that lifetime issues are simple when using Intern.

Example

use internment::Intern;

let x = Intern::new("hello");
let y = Intern::new("world");
assert_ne!(x, y);
assert_eq!(x, Intern::new("hello"));
assert_eq!(*x, "hello"); // dereference an Intern like a pointer

Methods

impl<T: Eq + Hash + Send + 'static> Intern<T>

pub fn new(val: T) -> Intern<T>

Intern a value. If this value has not previously been interned, then new will allocate a spot for the value on the heap. Otherwise, it will return a pointer to the object previously allocated.

Note that Intern::new is a bit slow, since it needs to check a HashSet protected by a Mutex.

pub fn num_objects_interned(&self) -> usize

See how many objects have been interned. This may be helpful in analyzing memory use.

Trait Implementations

impl<T> Clone for Intern<T>

fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Copy for Intern<T>

An Intern is Copy, which is unusal for a pointer. This is safe because we never free the data pointed to by an Intern.

impl<T> Send for Intern<T>

impl<T> Sync for Intern<T>

impl<T: Debug> Fits64 for Intern<T>

The Fits64 implementation for Intern<T> is designed to normally give (relatively) small numbers, by XORing with a fixed pointer that is also on the heap. This should make the most significant bits of the resulting u64 be zero, which will mean that Set64 (which is space-efficient in storing small integers) can store this result in fewer than 8 bytes.

unsafe fn from_u64(x: u64) -> Self

Convert back from a u64. This is unsafe, since it is only infallible (and lossless) if the u64 originally came from type Self.

fn to_u64(self) -> u64

Convert to a u64. This should be infallible.

fn test_fits64(self) -> bool

verify that the conversion is lossless

impl<T> AsRef<T> for Intern<T>

Important traits for &'a mut R

impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn as_ref(&self) -> &T

Performs the conversion.

impl<T> Borrow<T> for Intern<T>

Important traits for &'a mut R

impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn borrow(&self) -> &T

Immutably borrows from an owned value.

impl<T> Deref for Intern<T>

type Target = T

The resulting type after dereferencing.

Important traits for &'a mut R

impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

fn deref(&self) -> &T

Dereferences the value.

impl<T: Display> Display for Intern<T>

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

Formats the value using the given formatter.

impl<T> Pointer for Intern<T>

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

Formats the value using the given formatter.

impl<T: Eq + Hash + Send + 'static> From<T> for Intern<T>

fn from(t: T) -> Self

Performs the conversion.

impl<T: Eq + Hash + Send + Default + 'static> Default for Intern<T>

fn default() -> Intern<T>

Returns the "default value" for a type.

impl<T> Hash for Intern<T>

The hash implementation returns the hash of the pointer value, not the hash of the value pointed to. This should be irrelevant, since there is a unique pointer for every value, but it is observable, since you could compare the hash of the pointer with hash of the data itself.

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<T> PartialEq for Intern<T>

fn eq(&self, other: &Intern<T>) -> 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<T> Eq for Intern<T>

impl<T: PartialOrd> PartialOrd for Intern<T>

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: &Self) -> bool

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

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

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

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

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

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

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

impl<T: Ord> Ord for Intern<T>

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<T: Serialize> Serialize for Intern<T>

fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl<'de, T: Eq + Hash + Send + 'static + Deserialize<'de>> Deserialize<'de> for Intern<T>

fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl<T: Debug> Debug for Intern<T>

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

Formats the value using the given formatter.