Struct edn::intern_set::InternSet

pub struct InternSet<T> where
    T: Eq + Hash,  { /* fields omitted */ }

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.

Methods

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

pub fn new() -> InternSet<T>

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

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

use edn::{InternSet, ValueRc};

let mut s = InternSet::new();

let one = "foo".to_string();
let two = ValueRc::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.len());
// assert!(&out_one.ptr_eq(&out_two));   // Nightly-only.

Methods from Deref<Target = HashSet<ValueRc<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;

pub fn hasher(&self) -> &S

Returns a reference to the set's BuildHasher.

Examples

use std::collections::HashSet;
use std::collections::hash_map::RandomState;

let hasher = RandomState::new();
let set: HashSet<i32> = HashSet::with_hasher(hasher);
let hasher: &RandomState = set.hasher();

pub fn capacity(&self) -> usize

Returns the number of elements the set can hold without reallocating.

Examples

use std::collections::HashSet;
let set: HashSet<i32> = HashSet::with_capacity(100);
assert!(set.capacity() >= 100);

pub fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted in the HashSet. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new allocation size overflows usize.

Examples

use std::collections::HashSet;
let mut set: HashSet<i32> = HashSet::new();
set.reserve(10);
assert!(set.capacity() >= 10);

pub fn shrink_to_fit(&mut self)

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 std::collections::HashSet;

let mut set = HashSet::with_capacity(100);
set.insert(1);
set.insert(2);
assert!(set.capacity() >= 100);
set.shrink_to_fit();
assert!(set.capacity() >= 2);

Important traits for Iter<'a, K>

impl<'a, K> Iterator for Iter<'a, K> type Item = &'a K;

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

An iterator visiting all elements in arbitrary order. The iterator element type is &'a T.

Examples

use std::collections::HashSet;
let mut set = HashSet::new();
set.insert("a");
set.insert("b");

// Will print in an arbitrary order.
for x in set.iter() {
    println!("{}", x);
}

Important traits for Difference<'a, T, S>

impl<'a, T, S> Iterator for Difference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash,  type Item = &'a T;

pub fn difference(&'a self, other: &'a HashSet<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 std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [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: HashSet<_> = a.difference(&b).collect();
assert_eq!(diff, [1].iter().collect());

// Note that difference is not symmetric,
// and `b - a` means something else:
let diff: HashSet<_> = b.difference(&a).collect();
assert_eq!(diff, [4].iter().collect());

Important traits for SymmetricDifference<'a, T, S>

impl<'a, T, S> Iterator for SymmetricDifference<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash,  type Item = &'a T;

pub fn symmetric_difference(
    &'a self,
    other: &'a HashSet<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 std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Print 1, 4 in arbitrary order.
for x in a.symmetric_difference(&b) {
    println!("{}", x);
}

let diff1: HashSet<_> = a.symmetric_difference(&b).collect();
let diff2: HashSet<_> = b.symmetric_difference(&a).collect();

assert_eq!(diff1, diff2);
assert_eq!(diff1, [1, 4].iter().collect());

Important traits for Intersection<'a, T, S>

impl<'a, T, S> Iterator for Intersection<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash,  type Item = &'a T;

pub fn intersection(
    &'a self,
    other: &'a HashSet<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 std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Print 2, 3 in arbitrary order.
for x in a.intersection(&b) {
    println!("{}", x);
}

let intersection: HashSet<_> = a.intersection(&b).collect();
assert_eq!(intersection, [2, 3].iter().collect());

Important traits for Union<'a, T, S>

impl<'a, T, S> Iterator for Union<'a, T, S> where
    S: BuildHasher,
    T: Eq + Hash,  type Item = &'a T;

pub fn union(&'a self, other: &'a HashSet<T, S>) -> Union<'a, T, S>

Visits the values representing the union, i.e. all the values in self or other, without duplicates.

Examples

use std::collections::HashSet;
let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let b: HashSet<_> = [4, 2, 3, 4].iter().cloned().collect();

// Print 1, 2, 3, 4 in arbitrary order.
for x in a.union(&b) {
    println!("{}", x);
}

let union: HashSet<_> = a.union(&b).collect();
assert_eq!(union, [1, 2, 3, 4].iter().collect());

pub fn len(&self) -> usize

Returns the number of elements in the set.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
assert_eq!(v.len(), 0);
v.insert(1);
assert_eq!(v.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if the set contains no elements.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
assert!(v.is_empty());
v.insert(1);
assert!(!v.is_empty());

Important traits for Drain<'a, K>

impl<'a, K> Iterator for Drain<'a, K> type Item = K;

pub fn drain(&mut self) -> Drain<T>

Clears the set, returning all elements in an iterator.

Examples

use std::collections::HashSet;

let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert!(!set.is_empty());

// print 1, 2, 3 in an arbitrary order
for i in set.drain() {
    println!("{}", i);
}

assert!(set.is_empty());

pub fn clear(&mut self)

Clears the set, removing all values.

Examples

use std::collections::HashSet;

let mut v = HashSet::new();
v.insert(1);
v.clear();
assert!(v.is_empty());

pub fn contains<Q>(&self, value: &Q) -> bool where
    Q: Hash + Eq + ?Sized,
    T: Borrow<Q>, 

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 std::collections::HashSet;

let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);

pub fn get<Q>(&self, value: &Q) -> Option<&T> where
    Q: Hash + Eq + ?Sized,
    T: Borrow<Q>, 

Returns a reference to the value in the set, if any, that is equal to the given 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 std::collections::HashSet;

let set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.get(&2), Some(&2));
assert_eq!(set.get(&4), None);

pub fn is_disjoint(&self, other: &HashSet<T, S>) -> bool

Returns true if self has no elements in common with other. This is equivalent to checking for an empty intersection.

Examples

use std::collections::HashSet;

let a: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let mut b = HashSet::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);

pub fn is_subset(&self, other: &HashSet<T, S>) -> bool

Returns true if the set is a subset of another, i.e. other contains at least all the values in self.

Examples

use std::collections::HashSet;

let sup: HashSet<_> = [1, 2, 3].iter().cloned().collect();
let mut set = HashSet::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);

pub fn is_superset(&self, other: &HashSet<T, S>) -> bool

Returns true if the set is a superset of another, i.e. self contains at least all the values in other.

Examples

use std::collections::HashSet;

let sub: HashSet<_> = [1, 2].iter().cloned().collect();
let mut set = HashSet::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);

pub fn insert(&mut self, value: T) -> bool

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.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();

assert_eq!(set.insert(2), true);
assert_eq!(set.insert(2), false);
assert_eq!(set.len(), 1);

pub fn replace(&mut self, value: T) -> Option<T>

Adds a value to the set, replacing the existing value, if any, that is equal to the given one. Returns the replaced value.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();
set.insert(Vec::<i32>::new());

assert_eq!(set.get(&[][..]).unwrap().capacity(), 0);
set.replace(Vec::with_capacity(10));
assert_eq!(set.get(&[][..]).unwrap().capacity(), 10);

pub fn remove<Q>(&mut self, value: &Q) -> bool where
    Q: Hash + Eq + ?Sized,
    T: Borrow<Q>, 

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.

Examples

use std::collections::HashSet;

let mut set = HashSet::new();

set.insert(2);
assert_eq!(set.remove(&2), true);
assert_eq!(set.remove(&2), false);

pub fn take<Q>(&mut self, value: &Q) -> Option<T> where
    Q: Hash + Eq + ?Sized,
    T: Borrow<Q>, 

Removes and returns the value in the set, if any, that is equal to the given one.

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 std::collections::HashSet;

let mut set: HashSet<_> = [1, 2, 3].iter().cloned().collect();
assert_eq!(set.take(&2), Some(2));
assert_eq!(set.take(&2), None);

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

Retains only the elements specified by the predicate.

In other words, remove all elements e such that f(&e) returns false.

Examples

use std::collections::HashSet;

let xs = [1,2,3,4,5,6];
let mut set: HashSet<isize> = xs.iter().cloned().collect();
set.retain(|&k| k % 2 == 0);
assert_eq!(set.len(), 3);

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 !=.

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

type Target = HashSet<ValueRc<T>>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

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

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.