Struct CascadeUsagesResolver 

pub struct CascadeUsagesResolver<T: LinkReference, L: Doublets<T>> { /* private fields */ }

Deletes everything that references a link before deleting the link itself.

Port of C# LinksCascadeUsagesResolver together with ILinksExtensions.DeleteAllUsages.

Deviation from C#

C# recurses through the facade and keeps no record of what it has already visited, so a reference cycle (a → b → a) makes it recurse until the stack overflows. This port threads a visited set through the cascade, so cyclic graphs terminate. The price is that the nested deletions run from this layer inwards rather than from the top of the stack. Each usage is explicitly reset to (null, null) before recursing, preserving the reset callbacks of the automatic resolution stack. Place this decorator above any other layers whose behaviour the cascade must observe. The initial reset of the requested link is left to NonNullContentsLinkDeletionResolver.

Implementations

impl<T: LinkReference, L: Doublets<T>> CascadeUsagesResolver<T, L>

pub const fn new(links: L) -> Self

Wraps links in a CascadeUsagesResolver.

pub const fn inner(&self) -> &L

Returns a shared reference to the wrapped store.

pub const fn inner_mut(&mut self) -> &mut L

Returns a mutable reference to the wrapped store.

pub fn into_inner(self) -> L

Unwraps the decorator and returns the wrapped store.

Trait Implementations

impl<T: LinkReference, L: Doublets<T> + Debug> Debug for CascadeUsagesResolver<T, L>

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

Formats the value using the given formatter.

impl<T: LinkReference, L: Doublets<T>> Doublets<T> for CascadeUsagesResolver<T, L>

fn get_link(&self, index: T) -> Option<Link<T>>

Returns the link at index, or None if it does not exist.

fn count_by(&self, query: impl ToQuery<T>) -> T

where Self: Sized,

Counts links matching query.

fn count(&self) -> T

where Self: Sized,

Returns the total number of links in the store.

fn create_by_with<F>( &mut self, query: impl ToQuery<T>, handler: F, ) -> Result<Flow, Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Creates a link matching query, calling handler on each created link.

fn create_by(&mut self, query: impl ToQuery<T>) -> Result<T, Error<T>>

where Self: Sized,

Creates a link matching query and returns its index.

fn create_with<F>(&mut self, handler: F) -> Result<Flow, Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Creates a new link and calls handler with the before/after states.

fn create(&mut self) -> Result<T, Error<T>>

where Self: Sized,

Creates a new uninitialized link and returns its index.

fn each_by<F>(&self, query: impl ToQuery<T>, handler: F) -> Flow

where F: FnMut(Link<T>) -> Flow, Self: Sized,

Iterates over links matching query, calling handler for each.

fn each<F>(&self, handler: F) -> Flow

where F: FnMut(Link<T>) -> Flow, Self: Sized,

Iterates over all links in the store, calling handler for each.

fn update_by_with<H>( &mut self, query: impl ToQuery<T>, change: impl ToQuery<T>, handler: H, ) -> Result<Flow, Error<T>>

where H: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Updates links matching query to change, calling handler with before/after.

fn update_by( &mut self, query: impl ToQuery<T>, change: impl ToQuery<T>, ) -> Result<T, Error<T>>

where Self: Sized,

Updates links matching query to change and returns the updated link’s index.

fn update_with<F>( &mut self, index: T, source: T, target: T, handler: F, ) -> Result<Flow, Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Updates the link at index to (index, source, target), calling handler.

fn update(&mut self, index: T, source: T, target: T) -> Result<T, Error<T>>

where Self: Sized,

Updates the link at index to (index, source, target) and returns the index.

fn delete_by_with<F>( &mut self, query: impl ToQuery<T>, handler: F, ) -> Result<Flow, Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Deletes links matching query, calling handler with before/after states.

fn delete_by(&mut self, query: impl ToQuery<T>) -> Result<T, Error<T>>

where Self: Sized,

Deletes links matching query and returns the deleted link’s index.

fn delete_with<F>(&mut self, index: T, handler: F) -> Result<Flow, Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Deletes the link at index, calling handler with before/after states.

fn delete(&mut self, index: T) -> Result<T, Error<T>>

where Self: Sized,

Deletes the link at index and returns its former index.

fn try_get_link(&self, index: T) -> Result<Link<T>, Error<T>>

Returns the link at index, or Err(Error::NotExists) if it does not exist.

fn delete_all(&mut self) -> Result<(), Error<T>>

where Self: Sized,

Deletes all links in reverse enumeration order. Links already removed by cascading deletions are skipped.

fn delete_query_with<F>( &mut self, query: impl ToQuery<T>, handler: F, ) -> Result<(), Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Deletes all links matching query, calling handler for each deletion. Duplicate matches are deleted once, in reverse order of their first occurrence.

fn delete_usages_with<F>( &mut self, index: T, handler: F, ) -> Result<(), Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Deletes each other link that uses index as a source or target once, calling handler for each deletion.

fn delete_usages(&mut self, index: T) -> Result<(), Error<T>>

where Self: Sized,

Deletes all links that use index as a source or target.

fn create_point(&mut self) -> Result<T, Error<T>>

where Self: Sized,

Creates a self-referential point link and returns its index.

fn create_link_with<F>( &mut self, source: T, target: T, handler: F, ) -> Result<Flow, Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Creates a link from source to target, calling handler with before/after states.

fn create_link(&mut self, source: T, target: T) -> Result<T, Error<T>>

where Self: Sized,

Creates a link from source to target and returns its index.

fn found(&self, query: impl ToQuery<T>) -> bool

where Self: Sized,

Returns true if at least one link matches query.

fn find(&self, query: impl ToQuery<T>) -> Option<Link<T>>

where Self: Sized,

Returns the first link matching query, or None.

fn search(&self, source: T, target: T) -> Option<T>

where Self: Sized,

Returns the index of a link with the given source and target, or None.

fn search_or(&self, source: T, target: T, default: T) -> T

where Self: Sized,

👎Deprecated:

use search instead

fn single(&self, query: impl ToQuery<T>) -> Option<Link<T>>

where Self: Sized,

Returns the link matching query only if exactly one link matches; None otherwise.

fn get_or_create(&mut self, source: T, target: T) -> Result<T, Error<T>>

where Self: Sized,

Returns the index of the (source, target) link, creating it if it does not exist.

fn count_usages(&self, index: T) -> Result<T, Error<T>>

where Self: Sized,

Returns the number of distinct other links that reference index as a source or target.

fn usages(&self, index: T) -> Result<Vec<T>, Error<T>>

where Self: Sized,

Returns the indices of distinct other links that reference index as a source or target.

fn exist(&self, link: T) -> bool

where Self: Sized,

Returns true if the link at link exists (internal or external).

fn has_usages(&self, link: T) -> bool

where Self: Sized,

Returns true if any other link references link as a source or target.

fn rebase_with<F>(&mut self, old: T, new: T, handler: F) -> Result<(), Error<T>>

where F: FnMut(Link<T>, Link<T>) -> Flow, Self: Sized,

Re-points all usages of old to new, calling handler for each update.

fn rebase(&mut self, old: T, new: T) -> Result<T, Error<T>>

where Self: Sized,

Re-points all usages of old to new and returns new.

fn rebase_and_delete(&mut self, old: T, new: T) -> Result<T, Error<T>>

where Self: Sized,

Re-points all usages of old to new, then deletes old. Returns new.

impl<T: LinkReference, L: Doublets<T>> Links<T> for CascadeUsagesResolver<T, L>

fn constants(&self) -> &LinksConstants<T>

Returns the store’s LinksConstants (any/null/range values).

fn count_links(&self, query: &[T]) -> T

Counts links that match query.

fn each_links(&self, query: &[T], handler: ReadHandler<'_, T>) -> Flow

Iterates over links matching query, calling handler for each.

fn create_links( &mut self, query: &[T], handler: WriteHandler<'_, T>, ) -> Result<Flow, Error<T>>

Creates one or more links matching query and reports each creation via handler.

fn update_links( &mut self, query: &[T], change: &[T], handler: WriteHandler<'_, T>, ) -> Result<Flow, Error<T>>

Updates links matching query to the new values in change, reporting via handler.

fn delete_links( &mut self, query: &[T], handler: WriteHandler<'_, T>, ) -> Result<Flow, Error<T>>

Deletes links matching query and reports each deletion via handler.