Struct Expr 

pub struct Expr { /* private fields */ }

A compiled expression.

Compiling is the only step that reads the source; evaluation is a walk over the compiled nodes, so a host that evaluates the same expression per task — a step condition, a parameter filled per process — compiles it once and keeps the Expr.

Implementations

impl Expr

pub fn compile(source: &str) -> Result<Expr>

Compile source, or return the byte offset the parse stopped at.

pub fn eval(&self, context: &Context) -> Result<Value>

Evaluate against context.

pub fn references(&self) -> Vec<&str>

The names this expression reads, deduplicated and sorted: variables, called functions, and the names of called methods (which a receiver may answer itself before the context is consulted).

A host that injects on demand — rather than filling a context with everything an expression might read — injects exactly these.

pub fn len(&self) -> usize

How many nodes the compiled expression holds, for a host that bounds what it accepts.

pub fn is_empty(&self) -> bool

Trait Implementations

impl Clone for Expr

fn clone(&self) -> Self

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.