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-rw-r--r--vendor/itertools/src/combinations.rs308
1 files changed, 0 insertions, 308 deletions
diff --git a/vendor/itertools/src/combinations.rs b/vendor/itertools/src/combinations.rs
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index 54a02755..00000000
--- a/vendor/itertools/src/combinations.rs
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@@ -1,308 +0,0 @@
-use core::array;
-use core::borrow::BorrowMut;
-use std::fmt;
-use std::iter::FusedIterator;
-
-use super::lazy_buffer::LazyBuffer;
-use alloc::vec::Vec;
-
-use crate::adaptors::checked_binomial;
-
-/// Iterator for `Vec` valued combinations returned by [`.combinations()`](crate::Itertools::combinations)
-pub type Combinations<I> = CombinationsGeneric<I, Vec<usize>>;
-/// Iterator for const generic combinations returned by [`.array_combinations()`](crate::Itertools::array_combinations)
-pub type ArrayCombinations<I, const K: usize> = CombinationsGeneric<I, [usize; K]>;
-
-/// Create a new `Combinations` from a clonable iterator.
-pub fn combinations<I: Iterator>(iter: I, k: usize) -> Combinations<I>
-where
- I::Item: Clone,
-{
- Combinations::new(iter, (0..k).collect())
-}
-
-/// Create a new `ArrayCombinations` from a clonable iterator.
-pub fn array_combinations<I: Iterator, const K: usize>(iter: I) -> ArrayCombinations<I, K>
-where
- I::Item: Clone,
-{
- ArrayCombinations::new(iter, array::from_fn(|i| i))
-}
-
-/// An iterator to iterate through all the `k`-length combinations in an iterator.
-///
-/// See [`.combinations()`](crate::Itertools::combinations) and [`.array_combinations()`](crate::Itertools::array_combinations) for more information.
-#[must_use = "iterator adaptors are lazy and do nothing unless consumed"]
-pub struct CombinationsGeneric<I: Iterator, Idx> {
- indices: Idx,
- pool: LazyBuffer<I>,
- first: bool,
-}
-
-/// A type holding indices of elements in a pool or buffer of items from an inner iterator
-/// and used to pick out different combinations in a generic way.
-pub trait PoolIndex<T>: BorrowMut<[usize]> {
- type Item;
-
- fn extract_item<I: Iterator<Item = T>>(&self, pool: &LazyBuffer<I>) -> Self::Item
- where
- T: Clone;
-
- fn len(&self) -> usize {
- self.borrow().len()
- }
-}
-
-impl<T> PoolIndex<T> for Vec<usize> {
- type Item = Vec<T>;
-
- fn extract_item<I: Iterator<Item = T>>(&self, pool: &LazyBuffer<I>) -> Vec<T>
- where
- T: Clone,
- {
- pool.get_at(self)
- }
-}
-
-impl<T, const K: usize> PoolIndex<T> for [usize; K] {
- type Item = [T; K];
-
- fn extract_item<I: Iterator<Item = T>>(&self, pool: &LazyBuffer<I>) -> [T; K]
- where
- T: Clone,
- {
- pool.get_array(*self)
- }
-}
-
-impl<I, Idx> Clone for CombinationsGeneric<I, Idx>
-where
- I: Iterator + Clone,
- I::Item: Clone,
- Idx: Clone,
-{
- clone_fields!(indices, pool, first);
-}
-
-impl<I, Idx> fmt::Debug for CombinationsGeneric<I, Idx>
-where
- I: Iterator + fmt::Debug,
- I::Item: fmt::Debug,
- Idx: fmt::Debug,
-{
- debug_fmt_fields!(Combinations, indices, pool, first);
-}
-
-impl<I: Iterator, Idx: PoolIndex<I::Item>> CombinationsGeneric<I, Idx> {
- /// Constructor with arguments the inner iterator and the initial state for the indices.
- fn new(iter: I, indices: Idx) -> Self {
- Self {
- indices,
- pool: LazyBuffer::new(iter),
- first: true,
- }
- }
-
- /// Returns the length of a combination produced by this iterator.
- #[inline]
- pub fn k(&self) -> usize {
- self.indices.len()
- }
-
- /// Returns the (current) length of the pool from which combination elements are
- /// selected. This value can change between invocations of [`next`](Combinations::next).
- #[inline]
- pub fn n(&self) -> usize {
- self.pool.len()
- }
-
- /// Returns a reference to the source pool.
- #[inline]
- pub(crate) fn src(&self) -> &LazyBuffer<I> {
- &self.pool
- }
-
- /// Return the length of the inner iterator and the count of remaining combinations.
- pub(crate) fn n_and_count(self) -> (usize, usize) {
- let Self {
- indices,
- pool,
- first,
- } = self;
- let n = pool.count();
- (n, remaining_for(n, first, indices.borrow()).unwrap())
- }
-
- /// Initialises the iterator by filling a buffer with elements from the
- /// iterator. Returns true if there are no combinations, false otherwise.
- fn init(&mut self) -> bool {
- self.pool.prefill(self.k());
- let done = self.k() > self.n();
- if !done {
- self.first = false;
- }
-
- done
- }
-
- /// Increments indices representing the combination to advance to the next
- /// (in lexicographic order by increasing sequence) combination. For example
- /// if we have n=4 & k=2 then `[0, 1] -> [0, 2] -> [0, 3] -> [1, 2] -> ...`
- ///
- /// Returns true if we've run out of combinations, false otherwise.
- fn increment_indices(&mut self) -> bool {
- // Borrow once instead of noise each time it's indexed
- let indices = self.indices.borrow_mut();
-
- if indices.is_empty() {
- return true; // Done
- }
- // Scan from the end, looking for an index to increment
- let mut i: usize = indices.len() - 1;
-
- // Check if we need to consume more from the iterator
- if indices[i] == self.pool.len() - 1 {
- self.pool.get_next(); // may change pool size
- }
-
- while indices[i] == i + self.pool.len() - indices.len() {
- if i > 0 {
- i -= 1;
- } else {
- // Reached the last combination
- return true;
- }
- }
-
- // Increment index, and reset the ones to its right
- indices[i] += 1;
- for j in i + 1..indices.len() {
- indices[j] = indices[j - 1] + 1;
- }
- // If we've made it this far, we haven't run out of combos
- false
- }
-
- /// Returns the n-th item or the number of successful steps.
- pub(crate) fn try_nth(&mut self, n: usize) -> Result<<Self as Iterator>::Item, usize>
- where
- I: Iterator,
- I::Item: Clone,
- {
- let done = if self.first {
- self.init()
- } else {
- self.increment_indices()
- };
- if done {
- return Err(0);
- }
- for i in 0..n {
- if self.increment_indices() {
- return Err(i + 1);
- }
- }
- Ok(self.indices.extract_item(&self.pool))
- }
-}
-
-impl<I, Idx> Iterator for CombinationsGeneric<I, Idx>
-where
- I: Iterator,
- I::Item: Clone,
- Idx: PoolIndex<I::Item>,
-{
- type Item = Idx::Item;
- fn next(&mut self) -> Option<Self::Item> {
- let done = if self.first {
- self.init()
- } else {
- self.increment_indices()
- };
-
- if done {
- return None;
- }
-
- Some(self.indices.extract_item(&self.pool))
- }
-
- fn nth(&mut self, n: usize) -> Option<Self::Item> {
- self.try_nth(n).ok()
- }
-
- fn size_hint(&self) -> (usize, Option<usize>) {
- let (mut low, mut upp) = self.pool.size_hint();
- low = remaining_for(low, self.first, self.indices.borrow()).unwrap_or(usize::MAX);
- upp = upp.and_then(|upp| remaining_for(upp, self.first, self.indices.borrow()));
- (low, upp)
- }
-
- #[inline]
- fn count(self) -> usize {
- self.n_and_count().1
- }
-}
-
-impl<I, Idx> FusedIterator for CombinationsGeneric<I, Idx>
-where
- I: Iterator,
- I::Item: Clone,
- Idx: PoolIndex<I::Item>,
-{
-}
-
-impl<I: Iterator> Combinations<I> {
- /// Resets this `Combinations` back to an initial state for combinations of length
- /// `k` over the same pool data source. If `k` is larger than the current length
- /// of the data pool an attempt is made to prefill the pool so that it holds `k`
- /// elements.
- pub(crate) fn reset(&mut self, k: usize) {
- self.first = true;
-
- if k < self.indices.len() {
- self.indices.truncate(k);
- for i in 0..k {
- self.indices[i] = i;
- }
- } else {
- for i in 0..self.indices.len() {
- self.indices[i] = i;
- }
- self.indices.extend(self.indices.len()..k);
- self.pool.prefill(k);
- }
- }
-}
-
-/// For a given size `n`, return the count of remaining combinations or None if it would overflow.
-fn remaining_for(n: usize, first: bool, indices: &[usize]) -> Option<usize> {
- let k = indices.len();
- if n < k {
- Some(0)
- } else if first {
- checked_binomial(n, k)
- } else {
- // https://en.wikipedia.org/wiki/Combinatorial_number_system
- // http://www.site.uottawa.ca/~lucia/courses/5165-09/GenCombObj.pdf
-
- // The combinations generated after the current one can be counted by counting as follows:
- // - The subsequent combinations that differ in indices[0]:
- // If subsequent combinations differ in indices[0], then their value for indices[0]
- // must be at least 1 greater than the current indices[0].
- // As indices is strictly monotonically sorted, this means we can effectively choose k values
- // from (n - 1 - indices[0]), leading to binomial(n - 1 - indices[0], k) possibilities.
- // - The subsequent combinations with same indices[0], but differing indices[1]:
- // Here we can choose k - 1 values from (n - 1 - indices[1]) values,
- // leading to binomial(n - 1 - indices[1], k - 1) possibilities.
- // - (...)
- // - The subsequent combinations with same indices[0..=i], but differing indices[i]:
- // Here we can choose k - i values from (n - 1 - indices[i]) values: binomial(n - 1 - indices[i], k - i).
- // Since subsequent combinations can in any index, we must sum up the aforementioned binomial coefficients.
-
- // Below, `n0` resembles indices[i].
- indices.iter().enumerate().try_fold(0usize, |sum, (i, n0)| {
- sum.checked_add(checked_binomial(n - 1 - *n0, k - i)?)
- })
- }
-}