Enum Expr 

pub enum Expr<T: Element> {
    Node(Node<T>),
    Or(Or<T>),
    And(And<T>),
    Choose(Choose<T>),
}

An expression describing which sets of nodes form a quorum.

Variants

Node(Node<T>)

A single node

Or(Or<T>)

At least one child expression must be satisfied

And(And<T>)

All child expressions must be satisfied

Choose(Choose<T>)

At least k child expressions must be satisfied

Implementations

impl<T: Element> Expr<T>

pub fn quorums(&self) -> Box<dyn Iterator<Item = HashSet<T>> + '_>

Iterate over the quorums of this expression.

The same quorum can be produced more than once (for example by a + a), and non-minimal quorums are included (for example {a, b} from a + a * b).

pub fn is_quorum(&self, xs: &HashSet<T>) -> bool

Whether xs contains a quorum of this expression.

pub fn elements(&self) -> HashSet<T>

The identifiers of all nodes in this expression.

pub fn nodes(&self) -> HashSet<Node<T>>

All nodes in this expression.

If the same identifier appears more than once with different capacities or latency, the first occurrence (in left-to-right order) wins.

pub fn dual(&self) -> Self

The dual expression: Or and And swap, and choose(k, n) becomes choose(n - k + 1, n).

Every quorum of an expression intersects every quorum of its dual.

pub fn dup_free(&self) -> bool

Whether every node identifier appears at most once.

pub fn resilience(&self) -> usize

The resilience: the largest number of nodes that can fail while some quorum is still fully alive.

This equals min_hitting_set(quorums) - 1. Duplicate-free expressions are solved in closed form. Otherwise the hitting set is solved exactly as an integer program over the minimal quorums.

Trait Implementations

impl<T: Element> Add for Expr<T>

Expr + Expr produces an Or expression, flattening nested Or children.

type Output = Expr<T>

The resulting type after applying the + operator.

fn add(self, rhs: Self) -> Self::Output

Performs the + operation.

impl<T: Clone + Element> Clone for Expr<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug + Element> Debug for Expr<T>

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

Formats the value using the given formatter.

impl<T: Element> Display for Expr<T>

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

Formats the value using the given formatter.

impl<T: Element> From<And<T>> for Expr<T>

fn from(e: And<T>) -> Self

Converts to this type from the input type.

impl<T: Element> From<Choose<T>> for Expr<T>

fn from(e: Choose<T>) -> Self

Converts to this type from the input type.

impl<T: Element> From<Node<T>> for Expr<T>

fn from(node: Node<T>) -> Self

Converts to this type from the input type.

impl<T: Element> From<Or<T>> for Expr<T>

fn from(e: Or<T>) -> Self

Converts to this type from the input type.

impl<T: Element> Mul for Expr<T>

Expr * Expr produces an And expression, flattening nested And children.

type Output = Expr<T>

The resulting type after applying the * operator.

fn mul(self, rhs: Self) -> Self::Output

Performs the * operation.

impl<T: PartialEq + Element> PartialEq for Expr<T>

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<T: PartialEq + Element> StructuralPartialEq for Expr<T>