Struct Environment 

pub struct Environment { /* private fields */ }

What every evaluation shares: parameters, calculated fields, custom functions, the culture and the clock. Keep one per run; it is not thread-safe.

Implementations

impl Environment

pub fn new() -> Self

An environment in US English, on the system clock.

pub fn culture(self, culture: Culture) -> Self

Sets the culture for formats.

pub fn formats(&self) -> &Culture

The culture in effect, for formatting outside expressions.

pub fn at(self, now: DateTime) -> Self

Fixes the clock (Today(), Now()), for tests and reproducible runs.

pub fn parameter(self, name: impl Into<String>, value: impl Into<Value>) -> Self

Sets a parameter, read as ?name.

pub fn calculated(self, name: impl Into<String>, expression: Criteria) -> Self

Adds a calculated field, read as [name].

pub fn register( self, name: &str, function: impl Fn(&[Value]) -> Result<Value, String> + 'static, ) -> Self

Adds a function to the language; names are case-insensitive.

use ravenrs_criteria::{Criteria, Environment, Scope, Value};

let env = Environment::new().register("Double", |args| {
    Ok(Value::Number(args[0].as_number().unwrap_or(0.0) * 2.0))
});
let c = Criteria::parse("double(21)").expect("valid");
let row = serde_json::json!({});
assert_eq!(Scope::new(&env).row(&row).evaluate(&c), Ok(Value::Number(42.0)));

pub fn has_function(&self, name: &str) -> bool

Whether a custom function with this name is registered.

Trait Implementations

impl Debug for Environment

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

Formats the value using the given formatter.

impl Default for Environment

fn default() -> Self

Returns the “default value” for a type.