Struct codd::expression::Empty

pub struct Empty<T> where
    T: Tuple,  { /* fields omitted */ }

Represents an empty instance containing no tuples.

Example:

use codd::{Database, expression::Empty};

let mut db = Database::new();
let empty = Empty::<i32>::new();

assert_eq!(Vec::<i32>::new(), db.evaluate(&empty).unwrap().into_tuples());

Implementations

impl<T> Empty<T> where
    T: Tuple, 

pub fn new() -> Self

Creates a new instance of Empty.

Trait Implementations

impl<T: Clone> Clone for Empty<T> where
    T: Tuple, 

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

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for Empty<T> where
    T: Tuple, 

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

Formats the value using the given formatter.

impl<T: Tuple> Default for Empty<T>

fn default() -> Self

Returns the "default value" for a type.

impl<T> Expression<T> for Empty<T> where
    T: Tuple, 

fn visit<V>(&self, visitor: &mut V) where
    V: Visitor, 

Visits this expression by a Visitor.

fn builder(&self) -> Builder<T, Self>

Returns an expression builder over this expression.

impl<T: Tuple> From<Empty<T>> for Mono<T>

fn from(empty: Empty<T>) -> Self

Performs the conversion.