universal_weave/
lib.rs

1//! General-purpose building blocks for [Loom](https://generative.ink/posts/loom-interface-to-the-multiverse/) implementations.
2//!
3//! This library aims to make building Loom implementations easier by providing the following primitives:
4//! - [`dependent::DependentWeave`] - A tree-based [`Weave`] where each [`Node`] depends on the contents of the previous Node.
5//!     - [`dependent::loro::DependentLoroWeave`] - A [`dependent::DependentWeave`] wrapper which adds collaborative editing using the [`loro`] CRDT library (requires `rkyv` and `loro` features to be enabled).
6//! - [`independent::IndependentWeave`] - A DAG-based [`Weave`] where each [`Node`] does *not* depend on the contents of the previous Node.
7//!
8//! Efficient (de)serialization is supported using `rkyv` and `serde`. Basic functionality for versioning serialized data is provided by [`versioning::VersionedBytes`] (requires `rkyv` feature to be enabled).
9//!
10
11#![no_std]
12#![forbid(non_ascii_idents)]
13#![warn(missing_docs)]
14#![warn(let_underscore)]
15#![warn(clippy::pedantic)]
16#![warn(clippy::cargo)]
17#![allow(clippy::multiple_crate_versions, reason = "Unresolvable")]
18#![warn(clippy::nursery)]
19#![warn(clippy::restriction)]
20#![allow(clippy::blanket_clippy_restriction_lints, reason = "Conflicting lint")]
21#![allow(clippy::allow_attributes, reason = "Conflicting lint")]
22#![allow(clippy::pattern_type_mismatch, reason = "Conflicting lint")]
23#![allow(clippy::separated_literal_suffix, reason = "Conflicting lint")]
24#![allow(
25    clippy::field_scoped_visibility_modifiers,
26    reason = "Used by IndependentWeave::from()"
27)]
28#![allow(
29    clippy::missing_inline_in_public_items,
30    reason = "Reasonable candidates have already been inlined"
31)]
32#![allow(clippy::exhaustive_enums, reason = "API")]
33#![allow(clippy::exhaustive_structs, reason = "API")]
34#![allow(clippy::little_endian_bytes, reason = "API")]
35#![allow(clippy::partial_pub_fields, reason = "API")]
36#![allow(clippy::pub_use, reason = "API")]
37#![allow(clippy::arbitrary_source_item_ordering, reason = "Readability")]
38#![allow(clippy::question_mark_used, reason = "Readability")]
39#![allow(clippy::single_call_fn, reason = "Readability")]
40#![allow(clippy::single_char_lifetime_names, reason = "Readability")]
41#![allow(clippy::else_if_without_else, reason = "Style")]
42#![allow(clippy::if_then_some_else_none, reason = "Style")]
43#![allow(clippy::implicit_return, reason = "Style")]
44#![allow(clippy::min_ident_chars, reason = "Style")]
45#![allow(clippy::mod_module_files, reason = "Style")]
46#![allow(clippy::module_name_repetitions, reason = "Style")]
47#![allow(clippy::multiple_inherent_impl, reason = "Style")]
48#![allow(clippy::try_err, reason = "Style")]
49#![allow(clippy::allow_attributes_without_reason)] // TODO
50#![allow(clippy::indexing_slicing)] // TODO
51#![allow(clippy::unwrap_in_result)] // TODO
52#![allow(clippy::unwrap_used)] // TODO
53#![allow(clippy::missing_docs_in_private_items)] // TODO
54#![allow(clippy::shadow_unrelated)] // TODO
55#![allow(clippy::shadow_reuse)] // TODO
56
57mod contract;
58pub mod dependent;
59pub mod independent;
60pub mod wrappers;
61
62#[cfg(feature = "rkyv")]
63pub mod versioning;
64
65pub use contracts;
66pub use hashbrown;
67pub use indexmap;
68
69#[cfg(feature = "rkyv")]
70pub use rkyv;
71
72#[cfg(feature = "loro")]
73pub use loro;
74
75extern crate alloc;
76
77use alloc::{collections::vec_deque::VecDeque, vec::Vec};
78use core::{
79    cmp::{Ordering, Reverse},
80    hash::{BuildHasher, Hash},
81};
82
83use hashbrown::{HashMap, HashSet, hash_map::Entry};
84
85#[cfg(feature = "serde")]
86pub use serde;
87
88/// An item within a [`Weave`] which can be connected to other items.
89#[must_use]
90pub trait Node<K, T>
91where
92    K: Hash + Copy + Eq + Ord,
93{
94    /// Identifiers corresponding to the node's parents.
95    type From;
96    /// Identifiers corresponding to the node's children.
97    type To;
98
99    /// Returns the node's unique identifier.
100    #[must_use]
101    fn id(&self) -> K;
102    /// Returns a reference to the identifiers corresponding to the node's parents.
103    #[must_use]
104    fn from(&self) -> &Self::From;
105    /// Returns a reference to the identifiers corresponding to the node's children.
106    #[must_use]
107    fn to(&self) -> &Self::To;
108    /// Returns `true` if the node is considered active.
109    ///
110    /// The meaning of this value can depend on the underlying [`Weave`] implementation.
111    #[must_use]
112    fn is_active(&self) -> bool;
113    /// Returns a reference to the node's contents.
114    #[must_use]
115    fn contents(&self) -> &T;
116}
117
118/// [`Node`] contents which can be split apart or merged together.
119pub trait DiscreteContents: Sized {
120    /// Splits the item at specified index.
121    ///
122    /// If splitting the item fails, the original contents are returned.
123    fn split(self, at: usize) -> DiscreteContentResult<Self>;
124    /// Merges two items together.
125    ///
126    /// If merging the two items fails, the original contents are returned in the order they were specified in.
127    fn merge(self, value: Self) -> DiscreteContentResult<Self>;
128}
129
130/// A type representing the results of an action on a [`DiscreteContents`] item.
131#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
132#[allow(missing_docs, reason = "Enum items are self-explanatory")]
133#[must_use]
134pub enum DiscreteContentResult<T> {
135    One(T),
136    Two(T, T),
137}
138
139/// [`Node`] contents which do not depend on the contents of other [`Node`] objects in order to be meaningful.
140pub trait IndependentContents {}
141
142/// [`Node`] contents which can be meaningfully deduplicated.
143///
144/// Deduplication must be symmetric: `a.is_duplicate_of(b)` implies `b.is_duplicate_of(a)`.
145pub trait DeduplicatableContents {
146    /// Tests if `self` and `other` should be considered duplicates of each other.
147    #[must_use]
148    fn is_duplicate_of(&self, other: &Self) -> bool;
149}
150
151/// A document linking together multiple [`Node`] objects without cyclical links.
152///
153/// # Deserialization
154///
155/// If a Weave implementation supports deserialization, it must validate internal consistency during the deserialization process in a way which is robust to untrusted inputs.
156///
157/// # Panics
158///
159/// All panics should be assumed to leave the Weave in a malformed state unless otherwise specified by the implementation.
160#[must_use]
161pub trait Weave<K, N, T>
162where
163    K: Hash + Copy + Eq + Ord,
164    N: Node<K, T>,
165{
166    /// Mapping between identifiers and nodes.
167    type Nodes;
168    /// Identifiers of root nodes (nodes which do not have any parents).
169    type Roots;
170
171    /// Returns the number of nodes stored within the Weave.
172    #[must_use]
173    fn len(&self) -> usize;
174    /// Returns `true` if the Weave does not contain any nodes.
175    #[must_use]
176    fn is_empty(&self) -> bool;
177    /// Returns a reference to the identifier:node mapping.
178    #[must_use]
179    fn nodes(&self) -> &Self::Nodes;
180    /// Returns a reference to the identifiers of root nodes (nodes which do not have any parents).
181    #[must_use]
182    fn roots(&self) -> &Self::Roots;
183    /// Returns `true` if the Weave contains a node with the specified identifier.
184    #[must_use]
185    fn contains(&self, id: &K) -> bool;
186    /// Returns `true` if the Weave contains an active node (`node.is_active() == true`) with the specified identifier.
187    ///
188    /// The meaning of this value can depend on the underlying Weave implementation.
189    #[must_use]
190    fn contains_active(&self, id: &K) -> bool;
191    /// Returns a reference to the node corresponding to the identifier.
192    #[must_use]
193    fn get_node(&self, id: &K) -> Option<&N>;
194    /// Builds a list of all node identifiers ordered by their positions in the Weave.
195    fn get_ordered_node_identifiers(&mut self, output: &mut Vec<K>);
196    /// Recursively builds a list of all children of the specified node ordered by their positions in the Weave.
197    fn get_ordered_node_identifiers_from(&mut self, id: &K, output: &mut Vec<K>);
198    /// Builds the longest contiguous path of active nodes which ends at a root node.
199    fn get_active_path(&mut self, output: &mut Vec<K>);
200    /// Builds a path through the Weave starting at the specified node and ending at a root node.
201    ///
202    /// In an [`ActivePathWeave`], this path will preferentially route through the active path.
203    fn get_path_from(&mut self, id: &K, output: &mut Vec<K>);
204    /// Inserts a node into the Weave, returning `true` if the insertion was successful.
205    ///
206    /// This function may change the active status of nodes if it is necessary to preserve internal consistency.
207    fn add_node(&mut self, node: N) -> bool;
208    /// Sets the active status of a node with the specified identifier.
209    ///
210    /// This function may change the active status of other nodes in an implementation-specific manner if it is necessary to preserve internal consistency.
211    fn set_node_active_status(&mut self, id: &K, value: bool) -> bool;
212    /// Removes a node with the specified identifier, returning its value if it was present within the Weave.
213    ///
214    /// This function may remove or update other nodes if it is necessary to preserve internal consistency.
215    ///
216    /// This function uses the same removal logic as [`Weave::remove_node_tracked`].
217    fn remove_node(&mut self, id: &K) -> Option<N>;
218    /// Removes a node with the specified identifier, returning `true` if it was present within the Weave.
219    ///
220    /// This function may remove or update other nodes if it is necessary to preserve internal consistency. Every removed node will be returned by the `on_removal` call, with removal ordering being defined by the `Weave` implementation.
221    ///
222    /// # Panics
223    ///
224    /// May panic if `on_removal` panics.
225    fn remove_node_tracked(&mut self, id: &K, on_removal: impl FnMut(N)) -> bool;
226    /// Removes all nodes from the Weave.
227    fn remove_all_nodes(&mut self);
228}
229
230/// A [`Weave`] containing document-wide metadata.
231pub trait MetadataWeave<K, N, T, M>: Weave<K, N, T>
232where
233    K: Hash + Copy + Eq + Ord,
234    N: Node<K, T>,
235{
236    /// Returns a reference to the Weave's associated metadata.
237    #[must_use]
238    fn metadata(&self) -> &M;
239    /// Mutable access to the Weave's associated metadata.
240    ///
241    /// # Panics
242    ///
243    /// May panic if `callback` panics.
244    fn metadata_mut<O>(&mut self, callback: impl FnOnce(&mut M) -> O) -> O;
245}
246
247/// A [`Weave`] where nodes can be bookmarked.
248pub trait BookmarkableWeave<K, N, T>: Weave<K, N, T>
249where
250    K: Hash + Copy + Eq + Ord,
251    N: Node<K, T>,
252{
253    /// Identifiers of bookmarked nodes.
254    type Bookmarks;
255
256    /// Returns a reference to the identifiers of bookmarked nodes.
257    #[must_use]
258    fn bookmarks(&self) -> &Self::Bookmarks;
259    /// Returns `true` if the Weave contains a bookmarked node with the specified identifier.
260    #[must_use]
261    fn contains_bookmark(&self, id: &K) -> bool;
262    /// Sets the bookmarked status of a node with the specified identifier.
263    fn set_node_bookmarked_status(&mut self, id: &K, value: bool) -> bool;
264}
265
266/// A [`Weave`] where the ordering of nodes is stable and can be user-defined.
267pub trait SortableWeave<K, N, T>: Weave<K, N, T>
268where
269    K: Hash + Copy + Eq + Ord,
270    N: Node<K, T>,
271{
272    /// Builds a list of all node identifiers ordered by their positions in the Weave.
273    ///
274    /// Unlike [`Weave::get_ordered_node_identifiers`], this function reverses the ordering of node children.
275    fn get_ordered_node_identifiers_mirrored(&mut self, output: &mut Vec<K>);
276    /// Recursively builds a list of all children of the specified node ordered by their positions in the Weave.
277    ///
278    /// Unlike [`Weave::get_ordered_node_identifiers_from`], this function reverses the ordering of node children.
279    fn get_ordered_node_identifiers_mirrored_from(&mut self, id: &K, output: &mut Vec<K>);
280    /// Sorts the child nodes of a parent node with the specified identifier using the comparison function `cmp`.
281    ///
282    /// # Panics
283    ///
284    /// May panic if `cmp` does not implement a [total order](https://en.wikipedia.org/wiki/Total_order), or if `cmp` itself panics.
285    fn sort_node_children_by(&mut self, id: &K, cmp: impl FnMut(&N, &N) -> Ordering) -> bool;
286    /// Sorts the identifiers of a parent node's children with the specified identifier using the comparison function `cmp`.
287    ///
288    /// # Panics
289    ///
290    /// May panic if `cmp` does not implement a [total order](https://en.wikipedia.org/wiki/Total_order), or if `cmp` itself panics.
291    fn sort_node_children_by_id(&mut self, id: &K, cmp: impl FnMut(&K, &K) -> Ordering) -> bool;
292    /// Sorts root nodes (nodes which do not have any parents) using the comparison function `cmp`.
293    ///
294    /// # Panics
295    ///
296    /// May panic if `cmp` does not implement a [total order](https://en.wikipedia.org/wiki/Total_order), or if `cmp` itself panics.
297    fn sort_roots_by(&mut self, cmp: impl FnMut(&N, &N) -> Ordering);
298    /// Sorts the identifiers of root nodes (nodes which do not have any parents) using the comparison function `cmp`.
299    ///
300    /// # Panics
301    ///
302    /// May panic if `cmp` does not implement a [total order](https://en.wikipedia.org/wiki/Total_order), or if `cmp` itself panics.
303    fn sort_roots_by_id(&mut self, cmp: impl FnMut(&K, &K) -> Ordering);
304}
305
306/// A [`Weave`] where the ordering of bookmarked nodes is stable and can be user-defined.
307pub trait SortableBookmarkableWeave<K, N, T>:
308    BookmarkableWeave<K, N, T> + SortableWeave<K, N, T>
309where
310    K: Hash + Copy + Eq + Ord,
311    N: Node<K, T>,
312{
313    /// Sorts bookmarked nodes using the comparison function `cmp`.
314    ///
315    /// # Panics
316    ///
317    /// May panic if `cmp` does not implement a [total order](https://en.wikipedia.org/wiki/Total_order), or if `cmp` itself panics.
318    fn sort_bookmarks_by(&mut self, cmp: impl FnMut(&N, &N) -> Ordering);
319    /// Sorts the identifiers of bookmarked nodes using the comparison function `cmp`.
320    ///
321    /// # Panics
322    ///
323    /// May panic if `cmp` does not implement a [total order](https://en.wikipedia.org/wiki/Total_order), or if `cmp` itself panics.
324    fn sort_bookmarks_by_id(&mut self, cmp: impl FnMut(&K, &K) -> Ordering);
325}
326
327/// A [`Weave`] where only one [`Node`] can be considered active at a time.
328pub trait ActiveSingularWeave<K, N, T>: Weave<K, N, T>
329where
330    K: Hash + Copy + Eq + Ord,
331    N: Node<K, T>,
332{
333    /// Returns the active node's identifier, if any.
334    #[must_use]
335    fn active(&self) -> Option<K>;
336}
337
338/// A [`Weave`] where every [`Node`] in the active path is always considered active.
339pub trait ActivePathWeave<K, N, T>: Weave<K, N, T>
340where
341    K: Hash + Copy + Eq + Ord,
342    N: Node<K, T>,
343{
344    /// Identifiers of active nodes.
345    type Active;
346
347    /// Returns a reference to the identifiers of active nodes.
348    #[must_use]
349    fn active(&self) -> &Self::Active;
350    /// Replaces the active path.
351    ///
352    /// If the new active path would result in internal inconsistency, this function will correct the path in an implementation-specific manner.
353    fn set_active_path(&mut self, active: impl Iterator<Item = K>);
354}
355
356/// A [`Weave`] where [`Node`] objects do not depend on their parents in order to be meaningful.
357pub trait IndependentWeave<K, N, T>: Weave<K, N, T> + SemiIndependentWeave<K, N, T>
358where
359    K: Hash + Copy + Eq + Ord,
360    N: Node<K, T>,
361    T: IndependentContents,
362{
363    /// Moves a node with the specified identifier to a new set of parent nodes, returning `true` if the move was successful.
364    ///
365    /// This function may change the active status of other nodes if it is necessary to preserve internal consistency.
366    fn move_node(&mut self, id: &K, new_parents: &[K]) -> bool;
367}
368
369/// A [`Weave`] where [`Node`] objects do not depend on the *contents* of their parents in order to be meaningful.
370pub trait SemiIndependentWeave<K, N, T>: Weave<K, N, T>
371where
372    K: Hash + Copy + Eq + Ord,
373    N: Node<K, T>,
374    T: IndependentContents,
375{
376    /// Mutable access to the contents of a node with the specified identifier.
377    ///
378    /// # Panics
379    ///
380    /// May panic if `callback` panics.
381    fn get_contents_mut<O>(&mut self, id: &K, callback: impl FnOnce(&mut T) -> O) -> Option<O>;
382}
383
384/// A [`Weave`] where the contents of [`Node`] objects can be split and merged.
385pub trait DiscreteWeave<K, N, T>: Weave<K, N, T>
386where
387    K: Hash + Copy + Eq + Ord,
388    N: Node<K, T>,
389    T: DiscreteContents,
390{
391    /// Splits a node with the specified identifier at the given index, creating a new child node with the identifier `new_id`.
392    ///
393    /// Returns `false` if splitting the node failed or the node could not be found.
394    fn split_node(&mut self, id: &K, at: usize, new_id: K) -> bool;
395    /// Merges a node with the specified identifier with its parent, with the newly merged node inheriting the parent's identifier.
396    ///
397    /// Returns the identifier of the merged node if merging was successful.
398    fn merge_with_parent(&mut self, id: &K) -> Option<K>;
399}
400
401/// A [`Weave`] where [`Node`] objects can be meaningfully deduplicated by their contents.
402pub trait DeduplicatableWeave<K, N, T>: Weave<K, N, T>
403where
404    K: Hash + Copy + Eq + Ord,
405    N: Node<K, T>,
406    T: DeduplicatableContents,
407{
408    /// An iterator over the specified node's sibling identifiers which contain contents which are duplicates of the specified node's contents.
409    #[must_use]
410    fn find_duplicates(&self, id: &K) -> impl Iterator<Item = K>;
411}
412
413/// A read-only [`Weave`].
414#[must_use]
415pub trait ImmutableWeave<K, N, T>
416where
417    K: Hash + Copy + Eq + Ord,
418    N: Node<K, T>,
419{
420    /// Mapping between identifiers and nodes.
421    type Nodes;
422    /// Identifiers of root nodes (nodes which do not have any parents).
423    type Roots;
424
425    /// Returns the number of nodes stored within the Weave.
426    #[must_use]
427    fn len(&self) -> usize;
428    /// Returns `true` if the Weave does not contain any nodes.
429    #[must_use]
430    fn is_empty(&self) -> bool;
431    /// Returns a reference to the identifier:node mapping.
432    #[must_use]
433    fn nodes(&self) -> &Self::Nodes;
434    /// Returns a reference to the identifiers of root nodes (nodes which do not have any parents).
435    #[must_use]
436    fn roots(&self) -> &Self::Roots;
437    /// Returns `true` if the Weave contains a node with the specified identifier.
438    #[must_use]
439    fn contains(&self, id: &K) -> bool;
440    /// Returns `true` if the Weave contains an active node (`node.is_active() == true`) with the specified identifier.
441    ///
442    /// The meaning of this value can depend on the underlying Weave implementation.
443    #[must_use]
444    fn contains_active(&self, id: &K) -> bool;
445    /// Returns a reference to the node corresponding to the identifier.
446    #[must_use]
447    fn get_node(&self, id: &K) -> Option<&N>;
448    /// Builds a list of all node identifiers ordered by their positions in the Weave.
449    fn get_ordered_node_identifiers(&self, output: &mut Vec<K>);
450    /// Recursively builds a list of all children of the specified node ordered by their positions in the Weave.
451    fn get_ordered_node_identifiers_from(&self, id: &K, output: &mut Vec<K>);
452    /// Builds the longest contiguous path of active nodes which ends at a root node.
453    fn get_active_path(&self, output: &mut Vec<K>);
454    /// Builds a path through the Weave starting at the specified node and ending at a root node.
455    ///
456    /// In an [`ImmutableActivePathWeave`], this path will preferentially route through the active path.
457    fn get_path_from(&self, id: &K, output: &mut Vec<K>);
458}
459
460/// An [`ImmutableWeave`] containing document-wide metadata.
461pub trait ImmutableMetadataWeave<K, N, T, M>: ImmutableWeave<K, N, T>
462where
463    K: Hash + Copy + Eq + Ord,
464    N: Node<K, T>,
465{
466    /// Returns a reference to the Weave's associated metadata.
467    #[must_use]
468    fn metadata(&self) -> &M;
469}
470
471/// An [`ImmutableWeave`] where nodes can be bookmarked.
472pub trait ImmutableBookmarkableWeave<K, N, T>: ImmutableWeave<K, N, T>
473where
474    K: Hash + Copy + Eq + Ord,
475    N: Node<K, T>,
476{
477    /// Identifiers of bookmarked nodes.
478    type Bookmarks;
479
480    /// Returns a reference to the identifiers of bookmarked nodes.
481    #[must_use]
482    fn bookmarks(&self) -> &Self::Bookmarks;
483    /// Returns `true` if the Weave contains a bookmarked node with the specified identifier.
484    #[must_use]
485    fn contains_bookmark(&self, id: &K) -> bool;
486}
487
488/// An [`ImmutableWeave`] where the ordering of nodes is stable and can be user-defined.
489pub trait ImmutableSortableWeave<K, N, T>: ImmutableWeave<K, N, T>
490where
491    K: Hash + Copy + Eq + Ord,
492    N: Node<K, T>,
493{
494    /// Builds a list of all node identifiers ordered by their positions in the Weave.
495    ///
496    /// Unlike [`ImmutableWeave::get_ordered_node_identifiers`], this function reverses the ordering of node children.
497    fn get_ordered_node_identifiers_mirrored(&self, output: &mut Vec<K>);
498    /// Recursively builds a list of all children of the specified node ordered by their positions in the Weave.
499    ///
500    /// Unlike [`ImmutableWeave::get_ordered_node_identifiers_from`], this function reverses the ordering of node children.
501    fn get_ordered_node_identifiers_mirrored_from(&self, id: &K, output: &mut Vec<K>);
502}
503
504/// An [`ImmutableWeave`] where only one [`Node`] can be considered active at a time.
505pub trait ImmutableActiveSingularWeave<K, N, T>: ImmutableWeave<K, N, T>
506where
507    K: Hash + Copy + Eq + Ord,
508    N: Node<K, T>,
509{
510    /// Returns the active node's identifier, if any.
511    #[must_use]
512    fn active(&self) -> Option<K>;
513}
514
515/// An [`ImmutableWeave`] where every [`Node`] in the active path is always considered active.
516pub trait ImmutableActivePathWeave<K, N, T>: ImmutableWeave<K, N, T>
517where
518    K: Hash + Copy + Eq + Ord,
519    N: Node<K, T>,
520{
521    /// Identifiers of active nodes.
522    type Active;
523
524    /// Returns a reference to the identifiers of active nodes.
525    #[must_use]
526    fn active(&self) -> &Self::Active;
527}
528
529#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
530enum Step<A, B> {
531    Enter(A),
532    Exit(B),
533}
534
535fn topological_sort<'a, K, N, T, S>(
536    nodes: &'a HashMap<K, N, S>,
537    id: &'a K,
538    scratchpad: &mut Vec<K>,
539    identifiers: &mut Vec<K>,
540    identifier_set: &mut HashSet<K, S>,
541) where
542    K: Hash + Copy + Eq + Ord + 'a,
543    N: Node<K, T> + 'a,
544    <N as Node<K, T>>::From: 'a,
545    <N as Node<K, T>>::To: 'a,
546    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
547    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
548    S: BuildHasher + Default + Clone,
549{
550    scratchpad.push(*id);
551
552    while let Some(id) = scratchpad.pop() {
553        let node = &nodes[&id];
554
555        if !identifier_set.contains(&id)
556            && node
557                .from()
558                .into_iter()
559                .all(|parent| identifier_set.contains(parent))
560        {
561            identifiers.push(id);
562            identifier_set.insert(id);
563            scratchpad.extend(node.to().into_iter().rev().copied());
564        }
565    }
566}
567
568fn topological_sort_subgraph<'a, K, N, T, S>(
569    nodes: &'a HashMap<K, N, S>,
570    filter: &impl Fn(&K) -> bool,
571    id: &'a K,
572    scratchpad: &mut Vec<K>,
573    identifiers: &mut Vec<K>,
574    identifier_set: &mut HashSet<K, S>,
575) where
576    K: Hash + Copy + Eq + Ord + 'a,
577    N: Node<K, T> + 'a,
578    <N as Node<K, T>>::From: 'a,
579    <N as Node<K, T>>::To: 'a,
580    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
581    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
582    S: BuildHasher + Default + Clone,
583{
584    scratchpad.push(*id);
585
586    while let Some(id) = scratchpad.pop() {
587        let node = &nodes[&id];
588
589        if filter(&id)
590            && !identifier_set.contains(&id)
591            && node
592                .from()
593                .into_iter()
594                .all(|parent| identifier_set.contains(parent) || !filter(parent))
595        {
596            identifiers.push(id);
597            identifier_set.insert(id);
598            scratchpad.extend(node.to().into_iter().rev().copied());
599        }
600    }
601}
602
603fn topological_sort_subgraph_mirrored<'a, K, N, T, S>(
604    nodes: &'a HashMap<K, N, S>,
605    filter: &impl Fn(&K) -> bool,
606    id: &'a K,
607    scratchpad: &mut Vec<K>,
608    identifiers: &mut Vec<K>,
609    identifier_set: &mut HashSet<K, S>,
610) where
611    K: Hash + Copy + Eq + Ord + 'a,
612    N: Node<K, T> + 'a,
613    <N as Node<K, T>>::From: 'a,
614    <N as Node<K, T>>::To: 'a,
615    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
616    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
617    S: BuildHasher + Default + Clone,
618{
619    scratchpad.push(*id);
620
621    while let Some(id) = scratchpad.pop() {
622        let node = &nodes[&id];
623
624        if filter(&id)
625            && !identifier_set.contains(&id)
626            && node
627                .from()
628                .into_iter()
629                .all(|parent| identifier_set.contains(parent) || !filter(parent))
630        {
631            identifiers.push(id);
632            identifier_set.insert(id);
633            scratchpad.extend(node.to().into_iter().copied());
634        }
635    }
636}
637
638fn topological_sort_mirrored<'a, K, N, T, S>(
639    nodes: &'a HashMap<K, N, S>,
640    id: &'a K,
641    scratchpad: &mut Vec<K>,
642    identifiers: &mut Vec<K>,
643    identifier_set: &mut HashSet<K, S>,
644) where
645    K: Hash + Copy + Eq + Ord + 'a,
646    N: Node<K, T> + 'a,
647    <N as Node<K, T>>::From: 'a,
648    <N as Node<K, T>>::To: 'a,
649    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
650    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
651    S: BuildHasher + Default + Clone,
652{
653    scratchpad.push(*id);
654
655    while let Some(id) = scratchpad.pop() {
656        let node = &nodes[&id];
657
658        if !identifier_set.contains(&id)
659            && node
660                .from()
661                .into_iter()
662                .all(|parent| identifier_set.contains(parent))
663        {
664            identifiers.push(id);
665            identifier_set.insert(id);
666            scratchpad.extend(node.to().into_iter().copied());
667        }
668    }
669}
670
671fn detect_cycles<'a, K, N, T, S>(
672    nodes: &'a HashMap<K, N, S>,
673    roots: impl Iterator<Item = K>,
674    scratchpad: &mut Vec<Step<K, K>>,
675    scratchpad_map: &mut HashMap<K, bool, S>,
676) -> bool
677where
678    K: Hash + Copy + Eq + Ord + 'a,
679    N: Node<K, T> + 'a,
680    <N as Node<K, T>>::From: 'a,
681    <N as Node<K, T>>::To: 'a,
682    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
683    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator + ExactSizeIterator>,
684    S: BuildHasher + Default + Clone,
685{
686    for root in roots {
687        if scratchpad_map.contains_key(&root) {
688            continue;
689        }
690
691        scratchpad.push(Step::Enter(root));
692
693        while let Some(step) = scratchpad.pop() {
694            match step {
695                Step::Enter(id) => {
696                    scratchpad.push(Step::Exit(id));
697
698                    match scratchpad_map.entry(id) {
699                        Entry::Occupied(entry) => {
700                            if !entry.get() {
701                                return true;
702                            }
703                        }
704                        Entry::Vacant(entry) => {
705                            entry.insert_entry(false);
706
707                            scratchpad.extend(
708                                nodes[&id].to().into_iter().rev().copied().map(Step::Enter),
709                            );
710                        }
711                    }
712                }
713                Step::Exit(id) => {
714                    scratchpad_map.insert(id, true);
715                }
716            }
717        }
718    }
719
720    scratchpad_map.len() != nodes.len()
721}
722
723fn shortest_path_to_ancestor<'a, K, N, T, S>(
724    nodes: &'a HashMap<K, N, S>,
725    id: &'a K,
726    target: &impl Fn(&'a N) -> bool,
727    scratchpad: &mut VecDeque<K>,
728    scratchpad_map: &mut HashMap<K, K, S>,
729    scratchpad_set: &mut HashSet<K, S>,
730    path: &mut Vec<K>,
731) where
732    K: Hash + Copy + Eq + Ord + 'a,
733    N: Node<K, T> + 'a,
734    <N as Node<K, T>>::From: 'a,
735    <N as Node<K, T>>::To: 'a,
736    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
737    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
738    S: BuildHasher + Default + Clone,
739{
740    scratchpad.push_front(*id);
741    scratchpad_set.insert(*id);
742
743    while let Some(id) = scratchpad.pop_back() {
744        let node = &nodes[&id];
745
746        if target(node) {
747            scratchpad.clear();
748
749            path.push(id);
750
751            while let Some(child) = scratchpad_map.remove(path.last().unwrap()) {
752                path.push(child);
753            }
754
755            return;
756        }
757
758        for parent in node.from().into_iter().copied() {
759            if scratchpad_set.insert(parent) {
760                scratchpad.push_front(parent);
761                scratchpad_map.insert(parent, id);
762            }
763        }
764    }
765}
766
767fn longest_candidate_path_to_root<'a, K, N, T, S>(
768    nodes: &'a HashMap<K, N, S>,
769    topological_order: &[K],
770    is_candidate: &impl Fn(&K) -> bool,
771    scratchpad_map: &mut HashMap<K, usize, S>,
772    reversed_path: &mut Vec<K>,
773) where
774    K: Hash + Copy + Eq + Ord + 'a,
775    N: Node<K, T> + 'a,
776    <N as Node<K, T>>::From: 'a,
777    <N as Node<K, T>>::To: 'a,
778    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
779    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
780    S: BuildHasher + Default + Clone,
781{
782    let mut longest_distance = None;
783
784    for id in topological_order {
785        if !is_candidate(id) {
786            continue;
787        }
788
789        let node = &nodes[id];
790        let distance = if node.from().into_iter().next().is_none() {
791            Some(0)
792        } else {
793            node.from()
794                .into_iter()
795                .filter_map(|parent| scratchpad_map.get(parent).copied())
796                .max()
797                .map(|l| l.strict_add(1))
798        };
799
800        if let Some(distance) = distance {
801            scratchpad_map.insert(*id, distance);
802
803            if longest_distance.is_none_or(|(value, _)| distance > value) {
804                longest_distance = Some((distance, id));
805            }
806        }
807    }
808
809    let mut current = longest_distance.map(|(_, id)| id);
810
811    while let Some(id) = current {
812        reversed_path.push(*id);
813
814        current = nodes[id]
815            .from()
816            .into_iter()
817            .filter(|id| scratchpad_map.contains_key(*id))
818            .min_by_key(|id| Reverse(scratchpad_map[*id]));
819    }
820}
821
822fn ancestor_subgraph<'a, K, N, T, S>(
823    nodes: &'a HashMap<K, N, S>,
824    id: K,
825    scratchpad: &mut Vec<K>,
826    identifiers: &mut HashSet<K, S>,
827) where
828    K: Hash + Copy + Eq + Ord + 'a,
829    N: Node<K, T>,
830    <N as Node<K, T>>::From: 'a,
831    <N as Node<K, T>>::To: 'a,
832    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
833    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
834    S: BuildHasher + Default + Clone,
835{
836    scratchpad.push(id);
837
838    while let Some(id) = scratchpad.pop() {
839        if identifiers.insert(id) {
840            scratchpad.extend(nodes[&id].from().into_iter().rev().copied());
841        }
842    }
843}
844
845fn descendant_subgraph<'a, K, N, T, S>(
846    nodes: &'a HashMap<K, N, S>,
847    id: K,
848    scratchpad: &mut Vec<K>,
849    identifiers: &mut HashSet<K, S>,
850) where
851    K: Hash + Copy + Eq + Ord + 'a,
852    N: Node<K, T>,
853    <N as Node<K, T>>::From: 'a,
854    <N as Node<K, T>>::To: 'a,
855    &'a N::From: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
856    &'a N::To: IntoIterator<Item = &'a K, IntoIter: DoubleEndedIterator>,
857    S: BuildHasher + Default + Clone,
858{
859    scratchpad.push(id);
860
861    while let Some(id) = scratchpad.pop() {
862        if identifiers.insert(id) {
863            scratchpad.extend(nodes[&id].to().into_iter().rev().copied());
864        }
865    }
866}
universal_weave/lib.rs

universal_weave/
lib.rs
