Struct MetaSet 

pub struct MetaSet { /* private fields */ }

A set that is lazily evaluated to another set on access, with an optional fast path for “contains”.

This can be useful for various cases. Especially when “contains” and “iter” have separate fast paths. For example, merge() (merge commits) obviously has a cheap “contains” fast path by checking if a given commit has multiple parents. However, if we want to iterating through the set, segmented changelog has a fast path by iterating flat segments, instead of testing commits one by one using the “contains” check.

MetaSet is different from LazySet: MetaSet’s evaluate function can return static or lazy or meta sets. LazySet does not support a “contains” fast path (yet).

MetaSet is different from a pure filtering set (ex. only has “contains” fast path), as MetaSet supports fast path for iteration, if the underlying set supports it.

Implementations

impl MetaSet

pub fn from_evaluate_hints( evaluate: Box<dyn Fn() -> BoxFuture<'static, Result<Set>> + Send + Sync + 'static>, hints: Hints, ) -> Self

Constructs MetaSet from an evaluate function that returns a Set. The evaluate function is not called immediately.

pub fn with_contains( self, contains: Box<dyn for<'a> Fn(&'a MetaSet, &'a Vertex) -> BoxFuture<'a, Result<bool>> + Send + Sync>, ) -> Self

Provides a fast path for contains. Be careful to make sure “contains” matches “evaluate”.

pub async fn evaluate(&self) -> Result<Set>

Evaluate the set. Returns a new set.

pub fn evaluated(&self) -> Option<Set>

Returns the evaluated set if it was evaluated. Returns None if the set was not evaluated.

Trait Implementations

impl AsyncSetQuery for MetaSet

fn iter<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<BoxVertexStream>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Iterate through the set in defined order.

fn iter_rev<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<BoxVertexStream>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Iterate through the set in the reversed order.

fn count_slow<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<u64>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

“Slow” count implementation. Intended to be overridden.

fn size_hint<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = (u64, Option<u64>)> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Returns the bounds on the length of the set as a hint. The first item is the lower bound. The second item is the upper bound. This method should not block on long operations like waiting for network.

fn last<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<Option<Vertex>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

The last name in the set.

fn contains<'life0, 'life1, 'async_trait>( &'life0 self, name: &'life1 Vertex, ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Test if this set contains a given name.

fn contains_fast<'life0, 'life1, 'async_trait>( &'life0 self, name: &'life1 Vertex, ) -> Pin<Box<dyn Future<Output = Result<Option<bool>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Test contains in less than O(N) time. Returns None if cannot achieve in less than O(N) time.

fn as_any(&self) -> &dyn Any

For downcasting.

fn hints(&self) -> &Hints

Get or set optimization hints.

fn count<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<u64>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Number of names in this set. Do not override.

fn first<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<Option<Vertex>>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

The first name in the set.

fn is_empty<'life0, 'async_trait>( &'life0 self, ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait,

Test if this set is empty.

fn id_convert(&self) -> Option<&dyn IdConvert>

Get an optional IdConvert interface to check hints.

fn specialized_reverse(&self) -> Option<Set>

Specialized “reverse” implementation. Returns None to use the general purpose reverse implementation.

fn specialized_take(&self, n: u64) -> Option<Set>

Specialized “take” implementation. Returns None to use the general purpose implementation.

fn specialized_skip(&self, n: u64) -> Option<Set>

Specialized “take” implementation. Returns None to use the general purpose implementation.

fn specialized_flatten_id(&self) -> Option<Cow<'_, IdStaticSet>>

Specialized “flatten_id” implementation.

impl Debug for MetaSet

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

Formats the value using the given formatter.