Enum Retention 

pub enum Retention<C> {
    Ephemeral,
    Checkpoint {
        id: C,
        marking: Marking,
    },
    Marked,
    Reference,
}

A type for metadata that is used to determine when and how a leaf can be pruned from a tree.

Variants

Ephemeral

A leaf with Ephemeral retention will be pruned whenever its sibling is also a leaf with Ephemeral retention.

Checkpoint

A leaf with Checkpoint retention will have its position retained in the tree during pruning, but its value may be pruned (by merging with its sibling). If Checkpoint retention is removed from the leaf, then the retention for the leaf will become either Ephemeral, Marked, or Reference depending upon the value of the marking field.

Fields

id: C

marking: Marking

Marked

A leaf with Marked retention will be retained in the tree during pruning. Marked retention may only be explicitly removed.

Reference

A leaf with Reference retention will be retained in the tree during pruning. Reference retention is removed whenever the associated leaf is overwritten with a tree node having Ephemeral, Checkpoint, or Marked retention.

Implementations

impl<C> Retention<C>

pub fn is_checkpoint(&self) -> bool

Returns whether the associated node has Retention::Checkpoint retention.

pub fn is_marked(&self) -> bool

Returns whether the associated node has Retention::Marked retention or Retention::Checkpoint retention with Marking::Marked marking.

pub fn map<'a, D, F>(&'a self, f: F) -> Retention<D>

where F: Fn(&'a C) -> D,

Applies the provided function to the checkpoint identifier, if any, and returns a new Retention value having the same structure with the resulting value used as the checkpoint identifier.

Trait Implementations

impl<C> Clone for Retention<C>

where C: Clone,

fn clone(&self) -> Retention<C>

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<C> Debug for Retention<C>

where C: Debug,

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

Formats the value using the given formatter.

impl<C> Ord for Retention<C>

where C: Ord,

fn cmp(&self, other: &Retention<C>) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl<C> PartialEq for Retention<C>

where C: PartialEq,

fn eq(&self, other: &Retention<C>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<C> PartialOrd for Retention<C>

where C: PartialOrd,

fn partial_cmp(&self, other: &Retention<C>) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl<C> Copy for Retention<C>

where C: Copy,

impl<C> Eq for Retention<C>

where C: Eq,

impl<C> StructuralPartialEq for Retention<C>