Enum Expr

pub enum Expr {
    Var(Variable),
    Not(Box<Expr>),
    And(Box<Expr>, Box<Expr>),
    Or(Box<Expr>, Box<Expr>),
    Val(bool),
}

Represents a boolean expression.

Expressions can be:

• A Var(Variable): A propositional variable.
• A Not(Box<Expr>): The logical negation of an expression.
• An And(Box<Expr>, Box<Expr>): The logical conjunction of two expressions.
• An Or(Box<Expr>, Box<Expr>): The logical disjunction of two expressions.
• A Val(bool): A constant boolean value (true or false).

Variants

Var(Variable)

A propositional variable, identified by Variable.

Not(Box<Expr>)

Logical negation of an inner expression.

And(Box<Expr>, Box<Expr>)

Logical conjunction (AND) of two inner expressions.

Or(Box<Expr>, Box<Expr>)

Logical disjunction (OR) of two inner expressions.

Val(bool)

A constant boolean value (true or false).

Implementations

impl Expr

pub const fn is_val(&self) -> bool

Checks if the expression is a Val variant.

pub const fn is_var(&self) -> bool

Checks if the expression is a Var variant.

pub const fn is_not(&self) -> bool

Checks if the expression is a Not variant.

pub const fn is_and(&self) -> bool

Checks if the expression is an And variant.

pub const fn is_or(&self) -> bool

Checks if the expression is an Or variant.

pub const fn is_true(&self) -> bool

Checks if the expression is Val(true).

pub const fn is_false(&self) -> bool

Checks if the expression is Val(false).

pub fn unwrap_val(&self) -> bool

Unwraps the boolean value if the expression is a Val variant.

Panics

Panics if the expression is not Expr::Val(_).

pub fn unwrap_var(&self) -> Variable

Unwraps the variable identifier if the expression is a Var variant.

Panics

Panics if the expression is not Expr::Var(_).

pub fn ors(expressions: &[Self]) -> Self

Creates a new expression representing the disjunction (OR) of all expressions in the slice e.

e_1 OR e_2 OR ... OR e_n. The fold starts with Expr::Val(false) as the identity for OR (x OR false == x). If e is empty, Expr::Val(false) is returned.

Arguments

• e: A slice of Expr to be OR-ed together.

Returns

A new Expr representing the OR of all expressions in e.

Panics

Panics if e is empty, as the OR of no elements is not defined.

pub fn ands(expressions: &[Self]) -> Self

Creates a new expression representing the conjunction (AND) of all expressions in the slice e.

e_1 AND e_2 AND ... AND e_n. The fold starts with Expr::Val(true) as the identity for AND (x AND true == x). If e is empty, Expr::Val(true) is returned.

Arguments

• e: A slice of Expr to be AND-ed together.

Returns

A new Expr representing the AND of all expressions in e.

Panics

Should not panic, but if e is empty, it returns Expr::Val(true).

Trait Implementations

impl Clone for Expr

fn clone(&self) -> Expr

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Expr

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

Formats the value using the given formatter.

impl<T: Literal, S: LiteralStorage<T>> From<Expr> for Cnf<T, S>

fn from(expr: Expr) -> Self

Converts an Expr into a Cnf<T, S>. This is a convenience wrapper around to_cnf.

impl From<bool> for Expr

fn from(b: bool) -> Self

Converts a bool into an Expr::Val.

impl From<i32> for Expr

fn from(i: i32) -> Self

Converts an i32 (DIMACS-style literal) into an Expr. A positive i becomes Expr::Var(i.abs()). A negative i becomes Expr::Not(Box::new(Expr::Var(i.abs()))). Variable is assumed to be constructible from u32.

impl From<u32> for Expr

fn from(i: Variable) -> Self

Converts a Variable into an Expr::Var.

impl Hash for Expr

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 Ord for Expr

fn cmp(&self, other: &Expr) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Expr

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Expr

fn partial_cmp(&self, other: &Expr) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<T: Literal, S: LiteralStorage<T>> TryFrom<Cnf<T, S>> for Expr

fn try_from(cnf: Cnf<T, S>) -> Result<Self, Self::Error>

Attempts to convert a Cnf<T, S> back into an Expr. The resulting Expr will be a conjunction of disjunctions. Returns an error if the CNF is empty (contains no clauses).

type Error = &'static str

The type returned in the event of a conversion error.

impl Eq for Expr

impl StructuralPartialEq for Expr