Struct Context

pub struct Context {
    pub registry: Registry,
    pub now: DateTime<Local>,
    pub use_humanize: bool,
    pub save_previous_result: bool,
    pub previous_result: Option<Number>,
    /* private fields */
}

The evaluation context that contains unit definitions.

Fields

registry: Registry

Contains all the information about units.

now: DateTime<Local>

The current time, as set by the caller.

This is used instead of directly asking the OS for the time since it allows determinism in unit tests, and prevents edge cases like now - now being non-zero.

use_humanize: bool

Enables the use of chrono-humanize. It can be disabled for unit tests, as well as in wasm builds where the time API panics.

save_previous_result: bool

Whether to save the previous query result and make it available as the ans variable.

previous_result: Option<Number>

The previous query result.

Implementations

impl Context

pub fn new() -> Context

Creates a new, empty context

pub fn set_time(&mut self, time: DateTime<Local>)

pub fn update_time(&mut self)

pub fn load_dates(&mut self, dates: Vec<Vec<DatePattern>>)

pub fn lookup(&self, name: &str) -> Option<Number>

Given a unit name, returns its value if it exists. Supports SI prefixes, plurals, bare dimensions like length, and quantities.

pub fn canonicalize(&self, name: &str) -> Option<String>

Given a unit name, try to return a canonical name (expanding aliases and such)

pub fn describe_unit(&self, value: &Number) -> (bool, String)

Describes a value’s unit, gives true if the unit is reciprocal (e.g. you should prefix “1.0 / “ or replace “multiply” with “divide” when rendering it).

pub fn typo_dym<'a>(&'a self, what: &str) -> Option<&'a str>

pub fn unknown_unit_err(&self, name: &str) -> NotFoundError

pub fn humanize<Tz: TimeZone>(&self, date: DateTime<Tz>) -> Option<String>

pub fn load(&mut self, defs: Defs) -> Result<(), String>

Takes a parsed definitions.units from gnu_units::parse(). Returns a list of errors, if there were any.

pub fn eval(&self, expr: &Expr) -> Result<Value, QueryError>

Evaluates an expression to compute its value, excluding -> conversions.

pub fn eval_outer(&self, query: &Query) -> Result<QueryReply, QueryError>

👎Deprecated since 0.7.0: renamed to eval_query()

pub fn eval_query(&self, query: &Query) -> Result<QueryReply, QueryError>

Evaluates an expression, include -> conversions.

pub fn show( &self, raw: &Number, bottom: &Number, bottom_name: BTreeMap<String, isize>, bottom_const: Numeric, base: u8, digits: Digits, ) -> ConversionReply

Trait Implementations

impl Debug for Context

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

Formats the value using the given formatter.

impl Default for Context

fn default() -> Self

Equivalent to Context::new()