Enum Expression 

pub enum Expression<V>
where
    V: Clone,
{
    Boolean(BooleanExpr<V>),
    Natural(NaturalExpr<V>),
    Integer(IntegerExpr<V>),
    Float(FloatExpr<V>),
}

Expressions for the language internally used by PGs and CSs.

Expression<V> encodes the language in which V is the type of variables.

Note that not all expressions that can be formed are well-typed.

Variants

Boolean(BooleanExpr<V>)

Expression of Boolean type.

Natural(NaturalExpr<V>)

Expression of Natural type (unsigned integers).

Integer(IntegerExpr<V>)

Expression of Integer type.

Float(FloatExpr<V>)

Expression of Float type.

Implementations

impl<V> Expression<V>

where V: Clone,

pub fn type(&self) -> Type

Computes the type of an expression.

Fails if the expression is badly typed, e.g., if variables in it have type incompatible with the expression.

pub fn eval<R: Rng>(&self, vars: &dyn Fn(&V) -> Val, rng: &mut R) -> Val

Evaluates the expression with the given variable assignments and provided RNG.

Will assume the expression (with the variable assignment) is well-typed, and may panic if producing an unexpected type.

pub fn is_constant(&self) -> bool

Evals a constant expression. Returns an error if expression contains variables.

pub fn eval_constant(&self) -> Result<Val, TypeError>

Evals a constant expression. Returns an error if expression contains variables.

pub fn from_var(var: V, type: Type) -> Self

Creates an [Expression] out of a variable and the type of such variable.

pub fn equal_to(self, rhs: Self) -> Result<BooleanExpr<V>, TypeError>

Creates an Expression that predicates the equality of self and rhs, and returns error if comparison is not possible.

Equality of Boolean is represented as “if and only if”.

Equality of numerical types automatically casts the one of most-restrictive type to the less restrictive type of the other one: for example, NaturalExpr can be cast to IntegerExpr or FloatExpr; and [IntegerExpr] can be cast to [FloatExpr].

pub fn greater_than_or_equal_to( self, rhs: Self, ) -> Result<BooleanExpr<V>, TypeError>

Creates a BooleanExpr that compares numerical expressions self and rhs, and returns error if comparison is not possible.

Equality of numerical types automatically casts the one of most-restrictive type to the less restrictive type of the other one; see Self::equal_to.

pub fn greater_than(self, rhs: Self) -> Result<BooleanExpr<V>, TypeError>

Creates a BooleanExpr that compares numerical expressions self and rhs, and returns error if comparison is not possible.

Equality of numerical types automatically casts the one of most-restrictive type to the less restrictive type of the other one; see Self::equal_to.

pub fn less_than(self, rhs: Self) -> Result<BooleanExpr<V>, TypeError>

Creates a BooleanExpr that compares numerical expressions self and rhs, and returns error if comparison is not possible.

Equality of numerical types automatically casts the one of most-restrictive type to the less restrictive type of the other one; see Self::equal_to.

pub fn less_than_or_equal_to( self, rhs: Self, ) -> Result<BooleanExpr<V>, TypeError>

Creates a BooleanExpr that compares numerical expressions self and rhs, and returns error if comparison is not possible.

Equality of numerical types automatically casts the one of most-restrictive type to the less restrictive type of the other one; see Self::equal_to.

pub fn ite(self, then: Self, else: Self) -> Result<Self, TypeError>

Creates a BooleanExpr that compares numerical expressions self and rhs, and returns error if comparison is not possible.

Equality of numerical types automatically casts the one of most-restrictive type to the less restrictive type of the other one; see Self::equal_to.

Trait Implementations

impl<V: Clone> Add for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the + operator.

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

Performs the + operation.

impl<V: Clone> BitAnd for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the & operator.

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

Performs the & operation.

impl<V: Clone> BitOr for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the | operator.

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

Performs the | operation.

impl<V> Clone for Expression<V>

where V: Clone + Clone,

fn clone(&self) -> Expression<V>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<V> Debug for Expression<V>

where V: Clone + Debug,

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

Formats the value using the given formatter.

impl<V: Clone> Div for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the / operator.

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

Performs the / operation.

impl<V> From<Val> for Expression<V>

where V: Clone,

fn from(value: Val) -> Self

Converts to this type from the input type.

impl<V> From<bool> for Expression<V>

where V: Clone,

fn from(value: bool) -> Self

Converts to this type from the input type.

impl<V> From<f64> for Expression<V>

where V: Clone,

fn from(value: Float) -> Self

Converts to this type from the input type.

impl<V> From<i64> for Expression<V>

where V: Clone,

fn from(value: Integer) -> Self

Converts to this type from the input type.

impl<V> From<u64> for Expression<V>

where V: Clone,

fn from(value: Natural) -> Self

Converts to this type from the input type.

impl<V: Clone> Mul for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the * operator.

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

Performs the * operation.

impl<V: Clone> Neg for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the - operator.

fn neg(self) -> Self::Output

Performs the unary - operation.

impl<V: Clone> Not for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the ! operator.

fn not(self) -> Self::Output

Performs the unary ! operation.

impl<V: Clone> Rem for Expression<V>

type Output = Result<Expression<V>, TypeError>

The resulting type after applying the % operator.

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

Performs the % operation.

impl<V> TryFrom<Expression<V>> for BooleanExpr<V>

where V: Clone,

type Error = TypeError

The type returned in the event of a conversion error.

fn try_from(value: Expression<V>) -> Result<Self, Self::Error>

Performs the conversion.

impl<V> TryFrom<Expression<V>> for FloatExpr<V>

where V: Clone,

type Error = TypeError

The type returned in the event of a conversion error.

fn try_from(value: Expression<V>) -> Result<Self, Self::Error>

Performs the conversion.

impl<V> TryFrom<Expression<V>> for IntegerExpr<V>

where V: Clone,

type Error = TypeError

The type returned in the event of a conversion error.

fn try_from(value: Expression<V>) -> Result<Self, Self::Error>

Performs the conversion.

impl<V> TryFrom<Expression<V>> for NaturalExpr<V>

where V: Clone,

type Error = TypeError

The type returned in the event of a conversion error.

fn try_from(value: Expression<V>) -> Result<Self, Self::Error>

Performs the conversion.