Enum Expression

pub enum Expression {
    Variable(Variable),
    Literal(Value),
}

An un-evaluated Value.

Variants

Variable(Variable)

Un-evaluated.

Literal(Value)

Evaluated.

Implementations

impl Expression

pub fn with_literal<S: Into<Scalar>>(literal: S) -> Self

Create an expression from a scalar literal.

pub fn into_literal(self) -> Option<Value>

Convert into a literal if possible.

pub fn into_variable(self) -> Option<Variable>

Convert into a variable, if possible.

pub fn try_evaluate<'c>(&'c self, context: &'c Context<'_>) -> Option<&'c Value>

Convert to a Value.

pub fn evaluate<'c>(&'c self, context: &'c Context<'_>) -> Result<&'c Value>

Convert to a Value.

Trait Implementations

impl Clone for Expression

fn clone(&self) -> Expression

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Expression

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

Formats the value using the given formatter.

impl Display for Expression

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

Formats the value using the given formatter.

impl Extend<Expression> for Variable

fn extend<T: IntoIterator<Item = Expression>>(&mut self, iter: T)

Extends a collection with the contents of an iterator.

fn extend_one(&mut self, item: A)

🔬This is a nightly-only experimental API. (extend_one)

Extends a collection with exactly one element.

fn extend_reserve(&mut self, additional: usize)

🔬This is a nightly-only experimental API. (extend_one)

Reserves capacity in a collection for the given number of additional elements.

impl PartialEq for Expression

fn eq(&self, other: &Expression) -> 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 StructuralPartialEq for Expression