Struct just_a_tag::TagUnion

pub struct TagUnion(_);

A tag union, e.g. foo or foo+bar+baz (i.e. foo and bar and baz).

use just_a_tag::{Tag, TagUnion};

let union = TagUnion::from_str("foo").unwrap();
assert!(union.contains(&Tag::new("foo")));
assert_eq!(union.len(), 1);

let union = TagUnion::from_str("foo+bar").unwrap();
assert!(union.contains(&Tag::new("foo")));
assert!(union.contains(&Tag::new("bar")));
assert_eq!(union.len(), 2);

assert!(TagUnion::from_str("foo bar").is_err());

Implementations

impl TagUnion

pub fn matches_set(&self, values: &HashSet<Tag>) -> bool

Returns true if this tag union matches the value presented in the set.

use std::collections::HashSet;
use just_a_tag::{MatchesAnyTagUnion, Tag, TagUnion};

let unions = vec![
    TagUnion::from_str("foo").unwrap(),
    TagUnion::from_str("bar+baz").unwrap()
];

// foo, and bar+baz matches
let set_1 = HashSet::from_iter([Tag::new("foo"), Tag::new("bar"), Tag::new("baz")]);
assert!(unions.matches_set(&set_1));

// bar+baz matches
let set_2 = HashSet::from_iter([Tag::new("fubar"), Tag::new("bar"), Tag::new("baz")]);
assert!(unions.matches_set(&set_2));

// foo matches
let set_3 = HashSet::from_iter([Tag::new("foo"), Tag::new("bar")]);
assert!(unions.matches_set(&set_3));

// none match
let set_4 = HashSet::from_iter([Tag::new("fubar"), Tag::new("bar")]);
assert!(!unions.matches_set(&set_4));

pub fn insert(&mut self, tag: Tag) -> bool

Inserts a tag into this union. Returns whether the tag was inserted; that is:

• If the tag was not previously inserted, true is returned,
• If the tag was previously inserted, false is returned.

pub fn remove<T: Borrow<Tag>>(&mut self, tag: T) -> bool

Removes a tag from this union. Returns whether the tag was removed; that is:

• If the tag was previously inserted, true is returned,
• If the tag was not previously inserted, false is returned.

pub fn contains<T: Borrow<Tag>>(&self, tag: &T) -> bool

Returns whether this union contains the specified tag. That is:

• If the tag was previously inserted, true is returned,
• If the tag was not previously inserted, false is returned.

pub fn from_str<S: AsRef<str>>( value: S ) -> Result<TagUnion, TagUnionFromStringError>

Attempts to parse a TagUnion from a string-like input.

Methods from Deref<Target = HashSet<Tag>>

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 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}");
}

Performance

In the current implementation, iterating over set takes O(capacity) time instead of O(len) because it internally visits empty buckets too.

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());

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 difference<'a>( &'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::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

pub fn symmetric_difference<'a>( &'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::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

pub fn intersection<'a>( &'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.

When an equal element is present in self and other then the resulting Intersection may yield references to one or the other. This can be relevant if T contains fields which are not compared by its Eq implementation, and may hold different value between the two equal copies of T in the two sets.

Examples

use std::collections::HashSet;
let a = HashSet::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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());

pub fn union<'a>(&'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::from([1, 2, 3]);
let b = HashSet::from([4, 2, 3, 4]);

// 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 contains<Q>(&self, value: &Q) -> boolwhere T: Borrow<Q>, Q: Hash + Eq + ?Sized,

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::from([1, 2, 3]);
assert_eq!(set.contains(&1), true);
assert_eq!(set.contains(&4), false);

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

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::from([1, 2, 3]);
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::from([1, 2, 3]);
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::from([1, 2, 3]);
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::from([1, 2]);
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);

Trait Implementations

impl Clone for TagUnion

fn clone(&self) -> TagUnion

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for TagUnion

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

Formats the value using the given formatter.

impl Default for TagUnion

fn default() -> TagUnion

Returns the “default value” for a type.

impl Deref for TagUnion

type Target = HashSet<Tag, RandomState>

The resulting type after dereferencing.

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

Dereferences the value.

impl<'de> Deserialize<'de> for TagUnion

Available on crate feature serde only.

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

Deserialize this value from the given Serde deserializer.

impl FromIterator<Tag> for TagUnion

fn from_iter<T: IntoIterator<Item = Tag>>(iter: T) -> Self

Creates a value from an iterator.

impl FromStr for TagUnion

type Err = TagUnionFromStringError

The associated error which can be returned from parsing.

fn from_str(value: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for TagUnion

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, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq<TagUnion> for TagUnion

fn eq(&self, other: &TagUnion) -> 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 !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for TagUnion

impl StructuralEq for TagUnion

impl StructuralPartialEq for TagUnion