Struct mentat_core::intern_set::InternSet

pub struct InternSet<T> where
    T: Eq + Hash,  {
    pub inner: HashSet<Rc<T>>,
}

An InternSet allows to "intern" some potentially large values, maintaining a single value instance owned by the InternSet and leaving consumers with lightweight ref-counted handles to the large owned value. This can avoid expensive clone() operations.

In Mentat, such large values might be strings or arbitrary [a v] pairs.

See https://en.wikipedia.org/wiki/String_interning for discussion.

Fields

inner: HashSet<Rc<T>>

Methods

impl<T> InternSet<T> where     T: Eq + Hash,

pub fn new() -> InternSet<T>

pub fn len(&self) -> usize

pub fn intern<R: Into<Rc<T>>>(&mut self, value: R) -> Rc<T>

Intern a value, providing a ref-counted handle to the interned value.

use std::rc::Rc;
use mentat_core::intern_set::InternSet;

let mut s = InternSet::new();

let one = "foo".to_string();
let two = Rc::new("foo".to_string());

let out_one = s.intern(one);
assert_eq!(out_one, two);
// assert!(!&out_one.ptr_eq(&two));      // Nightly-only.

let out_two = s.intern(two);
assert_eq!(out_one, out_two);
assert_eq!(1, s.inner.len());
// assert!(&out_one.ptr_eq(&out_two));   // Nightly-only.

Trait Implementations

impl<T: Clone> Clone for InternSet<T> where     T: Eq + Hash,

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for InternSet<T> where     T: Eq + Hash,

fn fmt(&self, __arg_0: &mut Formatter) -> Result

Formats the value using the given formatter.

impl<T: Default> Default for InternSet<T> where     T: Eq + Hash,

fn default() -> InternSet<T>

Returns the "default value" for a type.

impl<T: Eq> Eq for InternSet<T> where     T: Eq + Hash,

impl<T: PartialEq> PartialEq for InternSet<T> where     T: Eq + Hash,

fn eq(&self, __arg_0: &InternSet<T>) -> bool

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

fn ne(&self, __arg_0: &InternSet<T>) -> bool

This method tests for !=.