Struct Generator 

pub struct Generator<'g> { /* private fields */ }

Generates strings that a rule accepts.

Deterministic: the same seed, options and sequence of calls produce the same strings, within a crate version (D15). Constructible only from a CheckedGrammar (D1).

Implementations

impl<'g> Generator<'g>

pub fn new(grammar: &'g CheckedGrammar, seed: u64) -> Self

Creates a generator seeded with seed.

pub fn with_options(self, options: GenOptions) -> Self

Sets the generation options.

pub const fn steps(&self) -> u64

How many nodes have been visited during the most recent call.

Reset by every Generator::generate, so one call’s budget is never spent by the last. That differs from crate::Recognizer::steps, which counts over the whole life of a recognizer: a generator is asked for many independent strings, while a recognizer is bound to one input and answers questions about it.

The counter GenOptions::max_steps limits, and what tests assert against rather than wall-clock time (D31).

pub fn uncovered(&mut self, rule: &str) -> Result<usize, GenError>

How many coverage units rule can reach that have not been covered yet.

Counted over the generatable graph, so a branch the generator would never take is not counted against it (D10). Zero means every branch reachable from this rule has been taken by some successful call.

With GenOptions::coverage set, this is also the bound: each successful call reduces it by at least one, so it reaches zero within this many calls.

Errors

As Generator::generate, for the same reasons: a rule that cannot be generated from has no coverage to report.

pub fn generate(&mut self, rule: &str) -> Result<String, GenError>

Generates one string that rule accepts.

Errors

GenError::UnknownRule if there is no such rule; the compatibility limits of SCOPE.md 6.6 if the rule can reach a prose value or an unrepresentable terminal; GenError::NoFiniteExpansion if it matches nothing at all; or a resource limit.