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[red-knot] Don't use separate ID types for each alist (#16415)
Regardless of whether #16408 and #16311 pan out, this part is worth pulling out as a separate PR. Before, you had to define a new `IndexVec` index type for each type of association list you wanted to create. Now there's a single index type that's internal to the alist implementation, and you use `List<K, V>` to store a handle to a particular list. This also adds some property tests for the alist implementation.
This commit is contained in:
Douglas Creager
GitHub
parent
fdf0915283
commit
ba44e9de13
7 changed files with 768 additions and 790 deletions
745
crates/red_knot_python_semantic/src/list.rs
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745
crates/red_knot_python_semantic/src/list.rs
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//! Sorted, arena-allocated association lists
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//!
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//! An [_association list_][alist], which is a linked list of key/value pairs. We additionally
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//! guarantee that the elements of an association list are sorted (by their keys), and that they do
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//! not contain any entries with duplicate keys.
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//!
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//! Association lists have fallen out of favor in recent decades, since you often need operations
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//! that are inefficient on them. In particular, looking up a random element by index is O(n), just
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//! like a linked list; and looking up an element by key is also O(n), since you must do a linear
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//! scan of the list to find the matching element. The typical implementation also suffers from
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//! poor cache locality and high memory allocation overhead, since individual list cells are
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//! typically allocated separately from the heap. We solve that last problem by storing the cells
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//! of an association list in an [`IndexVec`] arena.
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//!
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//! We exploit structural sharing where possible, reusing cells across multiple lists when we can.
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//! That said, we don't guarantee that lists are canonical — it's entirely possible for two lists
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//! with identical contents to use different list cells and have different identifiers.
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//!
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//! Given all of this, association lists have the following benefits:
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//!
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//! - Lists can be represented by a single 32-bit integer (the index into the arena of the head of
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//! the list).
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//! - Lists can be cloned in constant time, since the underlying cells are immutable.
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//! - Lists can be combined quickly (for both intersection and union), especially when you already
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//! have to zip through both input lists to combine each key's values in some way.
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//!
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//! There is one remaining caveat:
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//!
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//! - You should construct lists in key order; doing this lets you insert each value in constant time.
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//! Inserting entries in reverse order results in _quadratic_ overall time to construct the list.
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//!
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//! Lists are created using a [`ListBuilder`], and once created are accessed via a [`ListStorage`].
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//!
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//! ## Tests
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//!
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//! This module contains quickcheck-based property tests.
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//!
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//! These tests are disabled by default, as they are non-deterministic and slow. You can run them
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//! explicitly using:
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//!
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//! ```sh
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//! cargo test -p ruff_index -- --ignored list::property_tests
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//! ```
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//!
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//! The number of tests (default: 100) can be controlled by setting the `QUICKCHECK_TESTS`
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//! environment variable. For example:
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//!
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//! ```sh
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//! QUICKCHECK_TESTS=10000 cargo test …
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//! ```
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//!
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//! If you want to run these tests for a longer period of time, it's advisable to run them in
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//! release mode. As some tests are slower than others, it's advisable to run them in a loop until
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//! they fail:
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//!
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//! ```sh
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//! export QUICKCHECK_TESTS=100000
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//! while cargo test --release -p ruff_index -- \
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//! --ignored list::property_tests; do :; done
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//! ```
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//!
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//! [alist]: https://en.wikipedia.org/wiki/Association_list
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use std::cmp::Ordering;
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use std::marker::PhantomData;
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use std::ops::Deref;
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use ruff_index::{newtype_index, IndexVec};
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/// A handle to an association list. Use [`ListStorage`] to access its elements, and
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/// [`ListBuilder`] to construct other lists based on this one.
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#[derive(Clone, Copy, Debug, Eq, Ord, PartialEq, PartialOrd)]
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pub(crate) struct List<K, V = ()> {
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last: Option<ListCellId>,
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_phantom: PhantomData<(K, V)>,
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}
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impl<K, V> List<K, V> {
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pub(crate) const fn empty() -> List<K, V> {
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List::new(None)
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}
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const fn new(last: Option<ListCellId>) -> List<K, V> {
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List {
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last,
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_phantom: PhantomData,
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}
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}
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}
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impl<K, V> Default for List<K, V> {
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fn default() -> Self {
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List::empty()
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}
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}
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#[newtype_index]
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#[derive(PartialOrd, Ord)]
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struct ListCellId;
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/// Stores one or more association lists. This type provides read-only access to the lists. Use a
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/// [`ListBuilder`] to create lists.
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#[derive(Debug, Eq, PartialEq)]
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pub(crate) struct ListStorage<K, V = ()> {
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cells: IndexVec<ListCellId, ListCell<K, V>>,
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}
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/// Each association list is represented by a sequence of snoc cells. A snoc cell is like the more
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/// familiar cons cell `(a : (b : (c : nil)))`, but in reverse `(((nil : a) : b) : c)`.
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///
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/// **Terminology**: The elements of a cons cell are usually called `head` and `tail` (assuming
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/// you're not in Lisp-land, where they're called `car` and `cdr`). The elements of a snoc cell
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/// are usually called `rest` and `last`.
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#[derive(Debug, Eq, PartialEq)]
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struct ListCell<K, V> {
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rest: Option<ListCellId>,
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key: K,
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value: V,
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}
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/// Constructs one or more association lists.
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#[derive(Debug, Eq, PartialEq)]
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pub(crate) struct ListBuilder<K, V = ()> {
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storage: ListStorage<K, V>,
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/// Scratch space that lets us implement our list operations iteratively instead of
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/// recursively.
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///
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/// The snoc-list representation that we use for alists is very common in functional
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/// programming, and the simplest implementations of most of the operations are defined
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/// recursively on that data structure. However, they are not _tail_ recursive, which means
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/// that the call stack grows linearly with the size of the input, which can be a problem for
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/// large lists.
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///
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/// You can often rework those recursive implementations into iterative ones using an
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/// _accumulator_, but that comes at the cost of reversing the list. If we didn't care about
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/// ordering, that wouldn't be a problem. Since we want our lists to be sorted, we can't rely
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/// on that on its own.
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///
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/// The next standard trick is to use an accumulator, and use a fix-up step at the end to
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/// reverse the (reversed) result in the accumulator, restoring the correct order.
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///
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/// So, that's what we do! However, as one last optimization, we don't build up alist cells in
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/// our accumulator, since that would add wasteful cruft to our list storage. Instead, we use a
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/// normal Vec as our accumulator, holding the key/value pairs that should be stitched onto the
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/// end of whatever result list we are creating. For our fix-up step, we can consume a Vec in
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/// reverse order by `pop`ping the elements off one by one.
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scratch: Vec<(K, V)>,
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}
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impl<K, V> Default for ListBuilder<K, V> {
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fn default() -> Self {
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ListBuilder {
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storage: ListStorage {
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cells: IndexVec::default(),
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},
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scratch: Vec::default(),
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}
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}
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}
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impl<K, V> Deref for ListBuilder<K, V> {
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type Target = ListStorage<K, V>;
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fn deref(&self) -> &ListStorage<K, V> {
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&self.storage
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}
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}
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impl<K, V> ListBuilder<K, V> {
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/// Finalizes a `ListBuilder`. After calling this, you cannot create any new lists managed by
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/// this storage.
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pub(crate) fn build(mut self) -> ListStorage<K, V> {
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self.storage.cells.shrink_to_fit();
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self.storage
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}
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/// Adds a new cell to the list.
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///
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/// Adding an element always returns a non-empty list, which means we could technically use `I`
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/// as our return type, since we never return `None`. However, for consistency with our other
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/// methods, we always use `Option<I>` as the return type for any method that can return a
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/// list.
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#[allow(clippy::unnecessary_wraps)]
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fn add_cell(&mut self, rest: Option<ListCellId>, key: K, value: V) -> Option<ListCellId> {
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Some(self.storage.cells.push(ListCell { rest, key, value }))
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}
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/// Returns an entry pointing at where `key` would be inserted into a list.
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///
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/// Note that when we add a new element to a list, we might have to clone the keys and values
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/// of some existing elements. This is because list cells are immutable once created, since
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/// they might be shared across multiple lists. We must therefore create new cells for every
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/// element that appears after the new element.
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///
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/// That means that you should construct lists in key order, since that means that there are no
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/// entries to duplicate for each insertion. If you construct the list in reverse order, we
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/// will have to duplicate O(n) entries for each insertion, making it _quadratic_ to construct
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/// the entire list.
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pub(crate) fn entry(&mut self, list: List<K, V>, key: K) -> ListEntry<K, V>
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where
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K: Clone + Ord,
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V: Clone,
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{
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self.scratch.clear();
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// Iterate through the input list, looking for the position where the key should be
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// inserted. We will need to create new list cells for any elements that appear after the
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// new key. Stash those away in our scratch accumulator as we step through the input. The
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// result of the loop is that "rest" of the result list, which we will stitch the new key
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// (and any succeeding keys) onto.
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let mut curr = list.last;
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while let Some(curr_id) = curr {
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let cell = &self.storage.cells[curr_id];
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match key.cmp(&cell.key) {
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// We found an existing entry in the input list with the desired key.
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Ordering::Equal => {
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return ListEntry {
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builder: self,
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list,
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key,
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rest: ListTail::Occupied(curr_id),
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};
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}
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// The input list does not already contain this key, and this is where we should
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// add it.
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Ordering::Greater => {
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return ListEntry {
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builder: self,
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list,
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key,
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rest: ListTail::Vacant(curr_id),
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};
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}
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// If this key is in the list, it's further along. We'll need to create a new cell
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// for this entry in the result list, so add its contents to the scratch
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// accumulator.
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Ordering::Less => {
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let new_key = cell.key.clone();
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let new_value = cell.value.clone();
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self.scratch.push((new_key, new_value));
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curr = cell.rest;
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}
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}
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}
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// We made it all the way through the list without finding the desired key, so it belongs
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// at the beginning. (And we will unfortunately have to duplicate every existing cell if
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// the caller proceeds with inserting the new key!)
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ListEntry {
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builder: self,
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list,
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key,
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rest: ListTail::Beginning,
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}
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}
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}
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/// A view into a list, indicating where a key would be inserted.
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pub(crate) struct ListEntry<'a, K, V = ()> {
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builder: &'a mut ListBuilder<K, V>,
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list: List<K, V>,
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key: K,
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/// Points at the element that already contains `key`, if there is one, or the element
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/// immediately before where it would go, if not.
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rest: ListTail<ListCellId>,
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}
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enum ListTail<I> {
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/// The list does not already contain `key`, and it would go at the beginning of the list.
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Beginning,
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/// The list already contains `key`
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Occupied(I),
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/// The list does not already contain key, and it would go immediately after the given element
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Vacant(I),
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}
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impl<K, V> ListEntry<'_, K, V>
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where
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K: Clone,
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V: Clone,
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{
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fn stitch_up(self, rest: Option<ListCellId>, value: V) -> List<K, V> {
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let mut last = rest;
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last = self.builder.add_cell(last, self.key, value);
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while let Some((key, value)) = self.builder.scratch.pop() {
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last = self.builder.add_cell(last, key, value);
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}
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List::new(last)
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}
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/// Inserts a new key/value into the list if the key is not already present. If the list
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/// already contains `key`, we return the original list as-is, and do not invoke your closure.
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pub(crate) fn or_insert_with<F>(self, f: F) -> List<K, V>
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where
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F: FnOnce() -> V,
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{
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let rest = match self.rest {
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// If the list already contains `key`, we don't need to replace anything, and can
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// return the original list unmodified.
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ListTail::Occupied(_) => return self.list,
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// Otherwise we have to create a new entry and stitch it onto the list.
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ListTail::Beginning => None,
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ListTail::Vacant(index) => Some(index),
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};
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self.stitch_up(rest, f())
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}
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/// Inserts a new key and the default value into the list if the key is not already present. If
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/// the list already contains `key`, we return the original list as-is.
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pub(crate) fn or_insert_default(self) -> List<K, V>
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where
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V: Default,
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{
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self.or_insert_with(V::default)
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}
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}
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impl<K, V> ListBuilder<K, V> {
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/// Returns the intersection of two lists. The result will contain an entry for any key that
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/// appears in both lists. The corresponding values will be combined using the `combine`
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/// function that you provide.
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#[allow(clippy::needless_pass_by_value)]
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pub(crate) fn intersect_with<F>(
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&mut self,
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a: List<K, V>,
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b: List<K, V>,
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mut combine: F,
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) -> List<K, V>
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where
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K: Clone + Ord,
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V: Clone,
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F: FnMut(&V, &V) -> V,
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{
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self.scratch.clear();
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// Zip through the lists, building up the keys/values of the new entries into our scratch
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// vector. Continue until we run out of elements in either list. (Any remaining elements in
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// the other list cannot possibly be in the intersection.)
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let mut a = a.last;
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let mut b = b.last;
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while let (Some(a_id), Some(b_id)) = (a, b) {
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let a_cell = &self.storage.cells[a_id];
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let b_cell = &self.storage.cells[b_id];
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match a_cell.key.cmp(&b_cell.key) {
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// Both lists contain this key; combine their values
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Ordering::Equal => {
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let new_key = a_cell.key.clone();
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let new_value = combine(&a_cell.value, &b_cell.value);
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self.scratch.push((new_key, new_value));
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a = a_cell.rest;
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b = b_cell.rest;
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}
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// a's key is only present in a, so it's not included in the result.
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Ordering::Greater => a = a_cell.rest,
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// b's key is only present in b, so it's not included in the result.
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Ordering::Less => b = b_cell.rest,
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}
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}
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// Once the iteration loop terminates, we stitch the new entries back together into proper
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// alist cells.
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let mut last = None;
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while let Some((key, value)) = self.scratch.pop() {
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last = self.add_cell(last, key, value);
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}
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List::new(last)
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}
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}
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// ----
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// Sets
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impl<K> ListStorage<K, ()> {
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/// Iterates through the elements in a set _in reverse order_.
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#[allow(clippy::needless_pass_by_value)]
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pub(crate) fn iter_set_reverse(&self, set: List<K, ()>) -> ListSetReverseIterator<K> {
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ListSetReverseIterator {
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storage: self,
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curr: set.last,
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}
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}
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}
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pub(crate) struct ListSetReverseIterator<'a, K> {
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storage: &'a ListStorage<K, ()>,
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curr: Option<ListCellId>,
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}
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impl<'a, K> Iterator for ListSetReverseIterator<'a, K> {
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type Item = &'a K;
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fn next(&mut self) -> Option<Self::Item> {
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let cell = &self.storage.cells[self.curr?];
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self.curr = cell.rest;
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Some(&cell.key)
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}
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}
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impl<K> ListBuilder<K, ()> {
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/// Adds an element to a set.
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pub(crate) fn insert(&mut self, set: List<K, ()>, element: K) -> List<K, ()>
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where
|
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K: Clone + Ord,
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||||
{
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self.entry(set, element).or_insert_default()
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}
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|
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/// Returns the intersection of two sets. The result will contain any value that appears in
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/// both sets.
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pub(crate) fn intersect(&mut self, a: List<K, ()>, b: List<K, ()>) -> List<K, ()>
|
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where
|
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K: Clone + Ord,
|
||||
{
|
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self.intersect_with(a, b, |(), ()| ())
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}
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||||
}
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// -----
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// Tests
|
||||
|
||||
#[cfg(test)]
|
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mod tests {
|
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use super::*;
|
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|
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use std::fmt::Display;
|
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use std::fmt::Write;
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|
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// ----
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// Sets
|
||||
|
||||
impl<K> ListStorage<K>
|
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where
|
||||
K: Display,
|
||||
{
|
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fn display_set(&self, list: List<K, ()>) -> String {
|
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let elements: Vec<_> = self.iter_set_reverse(list).collect();
|
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let mut result = String::new();
|
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result.push('[');
|
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for element in elements.into_iter().rev() {
|
||||
if result.len() > 1 {
|
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result.push_str(", ");
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}
|
||||
write!(&mut result, "{element}").unwrap();
|
||||
}
|
||||
result.push(']');
|
||||
result
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn can_insert_into_set() {
|
||||
let mut builder = ListBuilder::<u16>::default();
|
||||
|
||||
// Build up the set in order
|
||||
let empty = List::empty();
|
||||
let set1 = builder.insert(empty, 1);
|
||||
let set12 = builder.insert(set1, 2);
|
||||
let set123 = builder.insert(set12, 3);
|
||||
let set1232 = builder.insert(set123, 2);
|
||||
assert_eq!(builder.display_set(empty), "[]");
|
||||
assert_eq!(builder.display_set(set1), "[1]");
|
||||
assert_eq!(builder.display_set(set12), "[1, 2]");
|
||||
assert_eq!(builder.display_set(set123), "[1, 2, 3]");
|
||||
assert_eq!(builder.display_set(set1232), "[1, 2, 3]");
|
||||
|
||||
// And in reverse order
|
||||
let set3 = builder.insert(empty, 3);
|
||||
let set32 = builder.insert(set3, 2);
|
||||
let set321 = builder.insert(set32, 1);
|
||||
let set3212 = builder.insert(set321, 2);
|
||||
assert_eq!(builder.display_set(empty), "[]");
|
||||
assert_eq!(builder.display_set(set3), "[3]");
|
||||
assert_eq!(builder.display_set(set32), "[2, 3]");
|
||||
assert_eq!(builder.display_set(set321), "[1, 2, 3]");
|
||||
assert_eq!(builder.display_set(set3212), "[1, 2, 3]");
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn can_intersect_sets() {
|
||||
let mut builder = ListBuilder::<u16>::default();
|
||||
|
||||
let empty = List::empty();
|
||||
let set1 = builder.insert(empty, 1);
|
||||
let set12 = builder.insert(set1, 2);
|
||||
let set123 = builder.insert(set12, 3);
|
||||
let set1234 = builder.insert(set123, 4);
|
||||
|
||||
let set2 = builder.insert(empty, 2);
|
||||
let set24 = builder.insert(set2, 4);
|
||||
let set245 = builder.insert(set24, 5);
|
||||
let set2457 = builder.insert(set245, 7);
|
||||
|
||||
let intersection = builder.intersect(empty, empty);
|
||||
assert_eq!(builder.display_set(intersection), "[]");
|
||||
let intersection = builder.intersect(empty, set1234);
|
||||
assert_eq!(builder.display_set(intersection), "[]");
|
||||
let intersection = builder.intersect(empty, set2457);
|
||||
assert_eq!(builder.display_set(intersection), "[]");
|
||||
let intersection = builder.intersect(set1, set1234);
|
||||
assert_eq!(builder.display_set(intersection), "[1]");
|
||||
let intersection = builder.intersect(set1, set2457);
|
||||
assert_eq!(builder.display_set(intersection), "[]");
|
||||
let intersection = builder.intersect(set2, set1234);
|
||||
assert_eq!(builder.display_set(intersection), "[2]");
|
||||
let intersection = builder.intersect(set2, set2457);
|
||||
assert_eq!(builder.display_set(intersection), "[2]");
|
||||
let intersection = builder.intersect(set1234, set2457);
|
||||
assert_eq!(builder.display_set(intersection), "[2, 4]");
|
||||
}
|
||||
|
||||
// ----
|
||||
// Maps
|
||||
|
||||
impl<K, V> ListStorage<K, V> {
|
||||
/// Iterates through the entries in a list _in reverse order by key_.
|
||||
#[allow(clippy::needless_pass_by_value)]
|
||||
pub(crate) fn iter_reverse(&self, list: List<K, V>) -> ListReverseIterator<'_, K, V> {
|
||||
ListReverseIterator {
|
||||
storage: self,
|
||||
curr: list.last,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub(crate) struct ListReverseIterator<'a, K, V> {
|
||||
storage: &'a ListStorage<K, V>,
|
||||
curr: Option<ListCellId>,
|
||||
}
|
||||
|
||||
impl<'a, K, V> Iterator for ListReverseIterator<'a, K, V> {
|
||||
type Item = (&'a K, &'a V);
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
let cell = &self.storage.cells[self.curr?];
|
||||
self.curr = cell.rest;
|
||||
Some((&cell.key, &cell.value))
|
||||
}
|
||||
}
|
||||
|
||||
impl<K, V> ListStorage<K, V>
|
||||
where
|
||||
K: Display,
|
||||
V: Display,
|
||||
{
|
||||
fn display(&self, list: List<K, V>) -> String {
|
||||
let entries: Vec<_> = self.iter_reverse(list).collect();
|
||||
let mut result = String::new();
|
||||
result.push('[');
|
||||
for (key, value) in entries.into_iter().rev() {
|
||||
if result.len() > 1 {
|
||||
result.push_str(", ");
|
||||
}
|
||||
write!(&mut result, "{key}:{value}").unwrap();
|
||||
}
|
||||
result.push(']');
|
||||
result
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn can_insert_into_map() {
|
||||
let mut builder = ListBuilder::<u16, u16>::default();
|
||||
|
||||
// Build up the map in order
|
||||
let empty = List::empty();
|
||||
let map1 = builder.entry(empty, 1).or_insert_with(|| 1);
|
||||
let map12 = builder.entry(map1, 2).or_insert_with(|| 2);
|
||||
let map123 = builder.entry(map12, 3).or_insert_with(|| 3);
|
||||
let map1232 = builder.entry(map123, 2).or_insert_with(|| 4);
|
||||
assert_eq!(builder.display(empty), "[]");
|
||||
assert_eq!(builder.display(map1), "[1:1]");
|
||||
assert_eq!(builder.display(map12), "[1:1, 2:2]");
|
||||
assert_eq!(builder.display(map123), "[1:1, 2:2, 3:3]");
|
||||
assert_eq!(builder.display(map1232), "[1:1, 2:2, 3:3]");
|
||||
|
||||
// And in reverse order
|
||||
let map3 = builder.entry(empty, 3).or_insert_with(|| 3);
|
||||
let map32 = builder.entry(map3, 2).or_insert_with(|| 2);
|
||||
let map321 = builder.entry(map32, 1).or_insert_with(|| 1);
|
||||
let map3212 = builder.entry(map321, 2).or_insert_with(|| 4);
|
||||
assert_eq!(builder.display(empty), "[]");
|
||||
assert_eq!(builder.display(map3), "[3:3]");
|
||||
assert_eq!(builder.display(map32), "[2:2, 3:3]");
|
||||
assert_eq!(builder.display(map321), "[1:1, 2:2, 3:3]");
|
||||
assert_eq!(builder.display(map3212), "[1:1, 2:2, 3:3]");
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn can_intersect_maps() {
|
||||
let mut builder = ListBuilder::<u16, u16>::default();
|
||||
|
||||
let empty = List::empty();
|
||||
let map1 = builder.entry(empty, 1).or_insert_with(|| 1);
|
||||
let map12 = builder.entry(map1, 2).or_insert_with(|| 2);
|
||||
let map123 = builder.entry(map12, 3).or_insert_with(|| 3);
|
||||
let map1234 = builder.entry(map123, 4).or_insert_with(|| 4);
|
||||
|
||||
let map2 = builder.entry(empty, 2).or_insert_with(|| 20);
|
||||
let map24 = builder.entry(map2, 4).or_insert_with(|| 40);
|
||||
let map245 = builder.entry(map24, 5).or_insert_with(|| 50);
|
||||
let map2457 = builder.entry(map245, 7).or_insert_with(|| 70);
|
||||
|
||||
let intersection = builder.intersect_with(empty, empty, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[]");
|
||||
let intersection = builder.intersect_with(empty, map1234, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[]");
|
||||
let intersection = builder.intersect_with(empty, map2457, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[]");
|
||||
let intersection = builder.intersect_with(map1, map1234, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[1:2]");
|
||||
let intersection = builder.intersect_with(map1, map2457, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[]");
|
||||
let intersection = builder.intersect_with(map2, map1234, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[2:22]");
|
||||
let intersection = builder.intersect_with(map2, map2457, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[2:40]");
|
||||
let intersection = builder.intersect_with(map1234, map2457, |a, b| a + b);
|
||||
assert_eq!(builder.display(intersection), "[2:22, 4:44]");
|
||||
}
|
||||
}
|
||||
|
||||
// --------------
|
||||
// Property tests
|
||||
|
||||
#[cfg(test)]
|
||||
mod property_tests {
|
||||
use super::*;
|
||||
|
||||
use std::collections::{BTreeMap, BTreeSet};
|
||||
|
||||
impl<K> ListBuilder<K>
|
||||
where
|
||||
K: Clone + Ord,
|
||||
{
|
||||
fn set_from_elements<'a>(&mut self, elements: impl IntoIterator<Item = &'a K>) -> List<K>
|
||||
where
|
||||
K: 'a,
|
||||
{
|
||||
let mut set = List::empty();
|
||||
for element in elements {
|
||||
set = self.insert(set, element.clone());
|
||||
}
|
||||
set
|
||||
}
|
||||
}
|
||||
|
||||
// For most of the tests below, we use a vec as our input, instead of a HashSet or BTreeSet,
|
||||
// since we want to test the behavior of adding duplicate elements to the set.
|
||||
|
||||
#[quickcheck_macros::quickcheck]
|
||||
#[ignore]
|
||||
#[allow(clippy::needless_pass_by_value)]
|
||||
fn roundtrip_set_from_vec(elements: Vec<u16>) -> bool {
|
||||
let mut builder = ListBuilder::default();
|
||||
let set = builder.set_from_elements(&elements);
|
||||
let expected: BTreeSet<_> = elements.iter().copied().collect();
|
||||
let actual = builder.iter_set_reverse(set).copied();
|
||||
actual.eq(expected.into_iter().rev())
|
||||
}
|
||||
|
||||
#[quickcheck_macros::quickcheck]
|
||||
#[ignore]
|
||||
#[allow(clippy::needless_pass_by_value)]
|
||||
fn roundtrip_set_intersection(a_elements: Vec<u16>, b_elements: Vec<u16>) -> bool {
|
||||
let mut builder = ListBuilder::default();
|
||||
let a = builder.set_from_elements(&a_elements);
|
||||
let b = builder.set_from_elements(&b_elements);
|
||||
let intersection = builder.intersect(a, b);
|
||||
let a_set: BTreeSet<_> = a_elements.iter().copied().collect();
|
||||
let b_set: BTreeSet<_> = b_elements.iter().copied().collect();
|
||||
let expected: Vec<_> = a_set.intersection(&b_set).copied().collect();
|
||||
let actual = builder.iter_set_reverse(intersection).copied();
|
||||
actual.eq(expected.into_iter().rev())
|
||||
}
|
||||
|
||||
impl<K, V> ListBuilder<K, V>
|
||||
where
|
||||
K: Clone + Ord,
|
||||
V: Clone + Eq,
|
||||
{
|
||||
fn set_from_pairs<'a, I>(&mut self, pairs: I) -> List<K, V>
|
||||
where
|
||||
K: 'a,
|
||||
V: 'a,
|
||||
I: IntoIterator<Item = &'a (K, V)>,
|
||||
I::IntoIter: DoubleEndedIterator,
|
||||
{
|
||||
let mut list = List::empty();
|
||||
for (key, value) in pairs.into_iter().rev() {
|
||||
list = self
|
||||
.entry(list, key.clone())
|
||||
.or_insert_with(|| value.clone());
|
||||
}
|
||||
list
|
||||
}
|
||||
}
|
||||
|
||||
fn join<K, V>(a: &BTreeMap<K, V>, b: &BTreeMap<K, V>) -> BTreeMap<K, (Option<V>, Option<V>)>
|
||||
where
|
||||
K: Clone + Ord,
|
||||
V: Clone + Ord,
|
||||
{
|
||||
let mut joined: BTreeMap<K, (Option<V>, Option<V>)> = BTreeMap::new();
|
||||
for (k, v) in a {
|
||||
joined.entry(k.clone()).or_default().0 = Some(v.clone());
|
||||
}
|
||||
for (k, v) in b {
|
||||
joined.entry(k.clone()).or_default().1 = Some(v.clone());
|
||||
}
|
||||
joined
|
||||
}
|
||||
|
||||
#[quickcheck_macros::quickcheck]
|
||||
#[ignore]
|
||||
#[allow(clippy::needless_pass_by_value)]
|
||||
fn roundtrip_list_from_vec(pairs: Vec<(u16, u16)>) -> bool {
|
||||
let mut builder = ListBuilder::default();
|
||||
let list = builder.set_from_pairs(&pairs);
|
||||
let expected: BTreeMap<_, _> = pairs.iter().copied().collect();
|
||||
let actual = builder.iter_reverse(list).map(|(k, v)| (*k, *v));
|
||||
actual.eq(expected.into_iter().rev())
|
||||
}
|
||||
|
||||
#[quickcheck_macros::quickcheck]
|
||||
#[ignore]
|
||||
#[allow(clippy::needless_pass_by_value)]
|
||||
fn roundtrip_list_intersection(
|
||||
a_elements: Vec<(u16, u16)>,
|
||||
b_elements: Vec<(u16, u16)>,
|
||||
) -> bool {
|
||||
let mut builder = ListBuilder::default();
|
||||
let a = builder.set_from_pairs(&a_elements);
|
||||
let b = builder.set_from_pairs(&b_elements);
|
||||
let intersection = builder.intersect_with(a, b, |a, b| a + b);
|
||||
let a_map: BTreeMap<_, _> = a_elements.iter().copied().collect();
|
||||
let b_map: BTreeMap<_, _> = b_elements.iter().copied().collect();
|
||||
let intersection_map = join(&a_map, &b_map);
|
||||
let expected: Vec<_> = intersection_map
|
||||
.into_iter()
|
||||
.filter_map(|(k, (v1, v2))| Some((k, v1? + v2?)))
|
||||
.collect();
|
||||
let actual = builder.iter_reverse(intersection).map(|(k, v)| (*k, *v));
|
||||
actual.eq(expected.into_iter().rev())
|
||||
}
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue