Struct edn::intern_set::InternSet [] [src]

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
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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
1.9.0
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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();

1.0.0
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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);

1.0.0
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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);

1.0.0
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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>
1.0.0
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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>
1.0.0
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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>
1.0.0
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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>
1.0.0
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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>
1.0.0
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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());

1.0.0
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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);

1.0.0
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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>
1.6.0
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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());

1.0.0
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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());

1.0.0
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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);

1.9.0
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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);

1.0.0
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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);

1.0.0
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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);

1.0.0
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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);

1.0.0
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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);

1.9.0
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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);

1.0.0
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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);

1.9.0
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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);

1.18.0
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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
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Returns a copy of the value. Read more

1.0.0
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Performs copy-assignment from source. Read more

impl<T: Debug> Debug for InternSet<T> where
    T: Eq + Hash
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Formats the value using the given formatter. Read more

impl<T: Default> Default for InternSet<T> where
    T: Eq + Hash
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Returns the "default value" for a type. Read more

impl<T: Eq> Eq for InternSet<T> where
    T: Eq + Hash
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impl<T: PartialEq> PartialEq for InternSet<T> where
    T: Eq + Hash
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This method tests for self and other values to be equal, and is used by ==. Read more

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This method tests for !=.

impl<T> Deref for InternSet<T> where
    T: Eq + Hash
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The resulting type after dereferencing.

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Dereferences the value.

impl<T> DerefMut for InternSet<T> where
    T: Eq + Hash
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Mutably dereferences the value.