Trait FixPasses 

pub trait FixPasses {
    // Required methods
    fn run_pass(&mut self, candidate_version: usize) -> PassResult;
    fn apply(&mut self, snapshot: usize) -> bool;
    fn snapshots_equal(&mut self, left: usize, right: usize) -> bool;
}

What: The work the loop drives. A trait is a named set of methods a type promises to provide, like a TS interface; &mut self lends the implementer for writing. Why: Exact candidate states can be large, so the implementer stores them (the incumbent used private files) and answers equality by snapshot number; the loop never holds content. Gotcha: Snapshot 0 is the state before the first pass and must exist before the loop starts.

In TS you’d write (pseudocode):

interface FixPasses { runPass(version: number): PassResult; apply(snapshot: number): boolean; snapshotsEqual(a: number, b: number): boolean }

Required Methods

fn run_pass(&mut self, candidate_version: usize) -> PassResult

Run every policy against the current state; candidate_version counts earlier changes.

fn apply(&mut self, snapshot: usize) -> bool

Apply the last pass’s corrections and store the new exact state under snapshot. Returns false when the corrections could not be applied.

fn snapshots_equal(&mut self, left: usize, right: usize) -> bool

Whether two stored states are equal byte for byte.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl<F: RepositoryFacts> FixPasses for DirectFixPasses<'_, F>

What: impl FixPasses for DirectFixPasses<'_, F> gives the loop its three operations. Why: The loop is tested without Git; these are the real passes.

In TS you’d write (pseudocode):

class DirectFixPasses implements FixPasses {}