Struct OrderTracker

pub struct OrderTracker<Item, Gap> { /* private fields */ }

A tracker for the order of items in a linked chunk.

This can be used to determine the absolute ordering of an item, and thus the relative ordering of two items in a linked chunk, in an efficient manner, thanks to OrderTracker::ordering. Internally, it keeps track of the relative ordering of the chunks themselves; given a Position in a linked chunk, the item ordering is the lexicographic ordering of the chunk in the linked chunk, and the internal position within the chunk. For the sake of ease, we return the absolute vector index of the item in the linked chunk.

It requires the full links’ metadata to be provided at creation time, so that it can also give an order for an item that’s not loaded yet, in the context of lazy-loading.

Implementations

impl<Item, Gap> OrderTracker<Item, Gap>

where Item: Clone,

pub fn flush_updates(&mut self, inhibit: bool)

Force flushing of the updates manually.

If inhibit is true (which is useful in the case of lazy-loading related updates, which shouldn’t affect the canonical, persisted linked chunk), the updates are ignored; otherwise, they are consumed normally.

pub fn map_updates(&mut self, updates: &[Update<Item, Gap>])

Apply some out-of-band updates to the ordering tracker.

This must only be used when the updates do not affect the observed linked chunk, but would affect the fully-loaded collection.

pub fn ordering(&self, event_pos: Position) -> Option<usize>

Given an event’s position, returns its final ordering in the current state of the linked chunk as a vector.

Useful to compare the ordering of multiple events.

Precondition: the reader must be up to date, i.e. Self::flush_updates must have been called before this method.

Will return None if the position doesn’t match a known chunk in the linked chunk, or if the chunk is a gap.

Trait Implementations

impl<Item, Gap> Debug for OrderTracker<Item, Gap>

where Item: Debug, Gap: Debug,

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

Formats the value using the given formatter.