Struct GenOptions 

pub struct GenOptions {
    pub max_depth: usize,
    pub spread: usize,
    pub coverage: bool,
    pub preserve_case: bool,
    pub max_output_len: Option<usize>,
    pub max_steps: Option<u64>,
}

How to generate.

Fields

max_depth: usize

How deep to recurse before switching to witness mode. Default DEFAULT_GEN_DEPTH.

This is a steering budget, not a safety limit: exhausting it does not fail, it makes the walk take the shortest derivation it knows. The safety limits are GenOptions::max_output_len and GenOptions::max_steps.

spread: usize

How many repetitions beyond the minimum to consider. Default DEFAULT_SPREAD.

A repetition takes a count uniformly from min..=min(max, min + spread), so *"a" with the default produces nought to three characters rather than an unbounded run.

coverage: bool

Steer towards branches that have not been taken yet, rather than choosing randomly.

With this set, and subject to the resource limits, each successful call covers at least one new coverage unit while any reachable one remains uncovered — so full coverage takes at most uncovered(rule) calls. That is a guarantee rather than a probability, and it does not depend on GenOptions::max_depth (D10, D38).

preserve_case: bool

Emit case-insensitive strings exactly as written, rather than varying their case.

Varying case is the more useful default for a fuzzer — "abc" really does match AbC — but it makes output unpredictable, so a test that compares generated text against an expected string wants this set.

max_output_len: Option<usize>

Give up once the output reaches this many scalar values. Default DEFAULT_MAX_OUTPUT_LEN.

Finite by default, because termination alone does not make generation practical: a grammar can demand a gigabyte without being wrong (D29).

max_steps: Option<u64>

Give up after visiting this many nodes. Default DEFAULT_MAX_STEPS.

Trait Implementations

impl Clone for GenOptions

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 GenOptions

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

Formats the value using the given formatter.

impl Default for GenOptions

fn default() -> Self

Returns the “default value” for a type.

impl Eq for GenOptions

impl PartialEq for GenOptions

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for GenOptions