Enum Expression

pub enum Expression {
    Float(f64),
    String(String),
    Selector(Selector),
    Group(Group),
    Function(Function),
    Operator(Operator),
}

A root expression node.

These are all valid root expression types.

Variants

Float(f64)

A single scalar float

String(String)

A single scalar string.

Prometheus’ docs claim strings aren’t currently implemented, but they’re valid as function arguments.

Selector(Selector)

A metric selector

Group(Group)

A grouped expression wrapped in parentheses

Function(Function)

A function call

Operator(Operator)

A binary operator expression

Implementations

impl Expression

pub fn group(self) -> Expression

Wraps this Expression in a Group, consuming this Expression but returning an owned Group.

pub fn return_value(&self) -> ReturnValue

Determines a predicted ReturnValue for this Expression. A ReturnValue includes a predicted data type and a set of label operations that may affect which labels are returned.

pub fn as_f64(&self) -> Option<f64>

If this Expression is a Float, returns its value. Otherwise, returns None.

pub fn as_str(&self) -> Option<&str>

If this Expression is a String, returns its value. Otherwise, returns None.

Trait Implementations

impl Clone for Expression

fn clone(&self) -> Expression

Returns a duplicate 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 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