Trait Column

pub trait Column: Mapping {
    // Required method
    fn iter(&self) -> impl Iterator<Item = (Self::Dom, &Self::Cod)>;

    // Provided methods
    fn values(&self) -> impl Iterator<Item = &Self::Cod> { ... }
    fn preimage(&self, y: &Self::Cod) -> impl Iterator<Item = Self::Dom> { ... }
    fn is_empty(&self) -> bool { ... }
}

A mapping with finite support.

While its domain and codomain can be infinite, such a mapping is defined at only finitely many values in the domain. It is thus a “column of data”, as found in data tables and relational databases.

Required Methods

fn iter(&self) -> impl Iterator<Item = (Self::Dom, &Self::Cod)>

Iterates over pairs stored by the column.

Provided Methods

fn values(&self) -> impl Iterator<Item = &Self::Cod>

Iterates over values stored by the column.

fn preimage(&self, y: &Self::Cod) -> impl Iterator<Item = Self::Dom>

Computes the preimage of the mapping at a value in the codomain.

Depending on whether the implementation maintains a reverse index for the mapping, this method can be cheap or expensive.

fn is_empty(&self) -> bool

Is the mapping not defined anywhere?

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl Column for SkelIndexedColumn

impl<K, V, S> Column for HashColumn<K, V, S>

where K: Eq + Hash + Clone, V: Eq + Clone, S: BuildHasher,

impl<K, V, S> Column for IndexedHashColumn<K, V, S>

where K: Eq + Hash + Clone, V: Eq + Hash + Clone, S: BuildHasher,

impl<T: Eq + Clone> Column for VecColumn<T>

impl<T: Eq + Hash + Clone> Column for IndexedVecColumn<T>