Enum avalog::Expr

pub enum Expr<T: Symbol = Arc<String>> {
    Sym(T),
    Var(Arc<String>),
    Rel(Box<Expr<T>>, Box<Expr<T>>),
    Ava(Box<Expr<T>>, Box<Expr<T>>),
    Inner(Box<Expr<T>>),
    UniqAva(Box<Expr<T>>),
    RoleOf(Box<Expr<T>>, Box<Expr<T>>),
    Eq(Box<Expr<T>>, Box<Expr<T>>),
    Neq(Box<Expr<T>>, Box<Expr<T>>),
    Has(Box<Expr<T>>, Box<Expr<T>>),
    App(Box<Expr<T>>, Box<Expr<T>>),
    AmbiguousRole(Box<Expr<T>>, Box<Expr<T>>, Box<Expr<T>>),
    AmbiguousRel(Box<Expr<T>>, Box<Expr<T>>, Box<Expr<T>>),
    Rule(Box<Expr<T>>, Vec<Expr<T>>),
    Ambiguity(bool),
    Tail,
    TailVar(Arc<String>),
    List(Vec<Expr<T>>),
}

Represents an expression.

Variants

Sym(T)

A symbol.

Var(Arc<String>)

A variable.

Rel(Box<Expr<T>>, Box<Expr<T>>)

A relation between two symbols.

Ava(Box<Expr<T>>, Box<Expr<T>>)

A 1-avatar of some expression.

Inner(Box<Expr<T>>)

Unwraps 1-avatar.

UniqAva(Box<Expr<T>>)

A 1-avatar q'(b) such that p(a) = q'(b).

RoleOf(Box<Expr<T>>, Box<Expr<T>>)

A role of expression.

Eq(Box<Expr<T>>, Box<Expr<T>>)

An equality, e.g. p(a) = b.

Neq(Box<Expr<T>>, Box<Expr<T>>)

An inequality, e.g. X != a.

Has(Box<Expr<T>>, Box<Expr<T>>)

A set membership relation, e.g. p(a) ∋ b.

App(Box<Expr<T>>, Box<Expr<T>>)

Apply an argument to a role, e.g. p(a).

AmbiguousRole(Box<Expr<T>>, Box<Expr<T>>, Box<Expr<T>>)

There is an ambiguous role.

AmbiguousRel(Box<Expr<T>>, Box<Expr<T>>, Box<Expr<T>>)

There is an ambiguous relation.

Rule(Box<Expr<T>>, Vec<Expr<T>>)

Defines a rule.

Ambiguity(bool)

Ambiguity summary.

This is true when some ambiguity is found, and false when no ambiguity is found.

Tail

Represents the tail of an argument list ...

TailVar(Arc<String>)

Represents the tail of an argument list bound a symbol ..x.

List(Vec<Expr<T>>)

Represents a list.

Implementations

impl<T: Symbol> Expr<T>

pub fn eval_lift(&self, eval: &T, top: bool) -> Expr<T>

Lifts apply with an eval role.

pub fn is_const(&self) -> bool

Returns true if expression contains no variables.

pub fn is_tail(&self) -> bool

Returns true if expression is a tail pattern.

pub fn arity(&self) -> usize

Returns the number of arguments in apply expression.

Trait Implementations

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

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

Returns a copy of the value.

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

Performs copy-assignment from source.

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

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

Formats the value using the given formatter.

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

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

Formats the value using the given formatter.

impl<T: Hash + Symbol> Hash for Expr<T>

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<T: Ord + Symbol> Ord for Expr<T>

fn cmp(&self, other: &Expr<T>) -> 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 + PartialOrd,

Restrict a value to a certain interval.

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

fn eq(&self, other: &Expr<T>) -> 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<T: PartialOrd + Symbol> PartialOrd for Expr<T>

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

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

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

This method tests less than (for self and other) and is used by the < operator.

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

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

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

This method tests greater than (for self and other) and is used by the > operator.

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

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

impl<T: Eq + Symbol> Eq for Expr<T>

impl<T: Symbol> StructuralPartialEq for Expr<T>