| use std::borrow::Borrow; |
| use std::cmp::Ordering; |
| use std::iter::FromIterator; |
| use std::mem; |
| use std::ops::{Bound, Index, IndexMut, RangeBounds}; |
| |
| mod index_map; |
| |
| pub use index_map::SortedIndexMultiMap; |
| |
| /// `SortedMap` is a data structure with similar characteristics as BTreeMap but |
| /// slightly different trade-offs: lookup, insertion, and removal are O(log(N)) |
| /// and elements can be iterated in order cheaply. |
| /// |
| /// `SortedMap` can be faster than a `BTreeMap` for small sizes (<50) since it |
| /// stores data in a more compact way. It also supports accessing contiguous |
| /// ranges of elements as a slice, and slices of already sorted elements can be |
| /// inserted efficiently. |
| #[derive( |
| Clone, |
| PartialEq, |
| Eq, |
| PartialOrd, |
| Ord, |
| Hash, |
| Default, |
| Debug, |
| RustcEncodable, |
| RustcDecodable |
| )] |
| pub struct SortedMap<K: Ord, V> { |
| data: Vec<(K, V)>, |
| } |
| |
| impl<K: Ord, V> SortedMap<K, V> { |
| #[inline] |
| pub fn new() -> SortedMap<K, V> { |
| SortedMap { data: vec![] } |
| } |
| |
| /// Construct a `SortedMap` from a presorted set of elements. This is faster |
| /// than creating an empty map and then inserting the elements individually. |
| /// |
| /// It is up to the caller to make sure that the elements are sorted by key |
| /// and that there are no duplicates. |
| #[inline] |
| pub fn from_presorted_elements(elements: Vec<(K, V)>) -> SortedMap<K, V> { |
| debug_assert!(elements.windows(2).all(|w| w[0].0 < w[1].0)); |
| |
| SortedMap { data: elements } |
| } |
| |
| #[inline] |
| pub fn insert(&mut self, key: K, mut value: V) -> Option<V> { |
| match self.lookup_index_for(&key) { |
| Ok(index) => { |
| let slot = unsafe { self.data.get_unchecked_mut(index) }; |
| mem::swap(&mut slot.1, &mut value); |
| Some(value) |
| } |
| Err(index) => { |
| self.data.insert(index, (key, value)); |
| None |
| } |
| } |
| } |
| |
| #[inline] |
| pub fn remove(&mut self, key: &K) -> Option<V> { |
| match self.lookup_index_for(key) { |
| Ok(index) => Some(self.data.remove(index).1), |
| Err(_) => None, |
| } |
| } |
| |
| #[inline] |
| pub fn get<Q>(&self, key: &Q) -> Option<&V> |
| where |
| K: Borrow<Q>, |
| Q: Ord + ?Sized, |
| { |
| match self.lookup_index_for(key) { |
| Ok(index) => unsafe { Some(&self.data.get_unchecked(index).1) }, |
| Err(_) => None, |
| } |
| } |
| |
| #[inline] |
| pub fn get_mut<Q>(&mut self, key: &Q) -> Option<&mut V> |
| where |
| K: Borrow<Q>, |
| Q: Ord + ?Sized, |
| { |
| match self.lookup_index_for(key) { |
| Ok(index) => unsafe { Some(&mut self.data.get_unchecked_mut(index).1) }, |
| Err(_) => None, |
| } |
| } |
| |
| #[inline] |
| pub fn clear(&mut self) { |
| self.data.clear(); |
| } |
| |
| /// Iterate over elements, sorted by key |
| #[inline] |
| pub fn iter(&self) -> ::std::slice::Iter<'_, (K, V)> { |
| self.data.iter() |
| } |
| |
| /// Iterate over the keys, sorted |
| #[inline] |
| pub fn keys(&self) -> impl Iterator<Item = &K> + ExactSizeIterator + DoubleEndedIterator { |
| self.data.iter().map(|&(ref k, _)| k) |
| } |
| |
| /// Iterate over values, sorted by key |
| #[inline] |
| pub fn values(&self) -> impl Iterator<Item = &V> + ExactSizeIterator + DoubleEndedIterator { |
| self.data.iter().map(|&(_, ref v)| v) |
| } |
| |
| #[inline] |
| pub fn len(&self) -> usize { |
| self.data.len() |
| } |
| |
| #[inline] |
| pub fn is_empty(&self) -> bool { |
| self.len() == 0 |
| } |
| |
| #[inline] |
| pub fn range<R>(&self, range: R) -> &[(K, V)] |
| where |
| R: RangeBounds<K>, |
| { |
| let (start, end) = self.range_slice_indices(range); |
| &self.data[start..end] |
| } |
| |
| #[inline] |
| pub fn remove_range<R>(&mut self, range: R) |
| where |
| R: RangeBounds<K>, |
| { |
| let (start, end) = self.range_slice_indices(range); |
| self.data.splice(start..end, ::std::iter::empty()); |
| } |
| |
| /// Mutate all keys with the given function `f`. This mutation must not |
| /// change the sort-order of keys. |
| #[inline] |
| pub fn offset_keys<F>(&mut self, f: F) |
| where |
| F: Fn(&mut K), |
| { |
| self.data.iter_mut().map(|&mut (ref mut k, _)| k).for_each(f); |
| } |
| |
| /// Inserts a presorted range of elements into the map. If the range can be |
| /// inserted as a whole in between to existing elements of the map, this |
| /// will be faster than inserting the elements individually. |
| /// |
| /// It is up to the caller to make sure that the elements are sorted by key |
| /// and that there are no duplicates. |
| #[inline] |
| pub fn insert_presorted(&mut self, mut elements: Vec<(K, V)>) { |
| if elements.is_empty() { |
| return; |
| } |
| |
| debug_assert!(elements.windows(2).all(|w| w[0].0 < w[1].0)); |
| |
| let start_index = self.lookup_index_for(&elements[0].0); |
| |
| let drain = match start_index { |
| Ok(index) => { |
| let mut drain = elements.drain(..); |
| self.data[index] = drain.next().unwrap(); |
| drain |
| } |
| Err(index) => { |
| if index == self.data.len() || elements.last().unwrap().0 < self.data[index].0 { |
| // We can copy the whole range without having to mix with |
| // existing elements. |
| self.data.splice(index..index, elements.drain(..)); |
| return; |
| } |
| |
| let mut drain = elements.drain(..); |
| self.data.insert(index, drain.next().unwrap()); |
| drain |
| } |
| }; |
| |
| // Insert the rest |
| for (k, v) in drain { |
| self.insert(k, v); |
| } |
| } |
| |
| /// Looks up the key in `self.data` via `slice::binary_search()`. |
| #[inline(always)] |
| fn lookup_index_for<Q>(&self, key: &Q) -> Result<usize, usize> |
| where |
| K: Borrow<Q>, |
| Q: Ord + ?Sized, |
| { |
| self.data.binary_search_by(|&(ref x, _)| x.borrow().cmp(key)) |
| } |
| |
| #[inline] |
| fn range_slice_indices<R>(&self, range: R) -> (usize, usize) |
| where |
| R: RangeBounds<K>, |
| { |
| let start = match range.start_bound() { |
| Bound::Included(ref k) => match self.lookup_index_for(k) { |
| Ok(index) | Err(index) => index, |
| }, |
| Bound::Excluded(ref k) => match self.lookup_index_for(k) { |
| Ok(index) => index + 1, |
| Err(index) => index, |
| }, |
| Bound::Unbounded => 0, |
| }; |
| |
| let end = match range.end_bound() { |
| Bound::Included(ref k) => match self.lookup_index_for(k) { |
| Ok(index) => index + 1, |
| Err(index) => index, |
| }, |
| Bound::Excluded(ref k) => match self.lookup_index_for(k) { |
| Ok(index) | Err(index) => index, |
| }, |
| Bound::Unbounded => self.data.len(), |
| }; |
| |
| (start, end) |
| } |
| |
| #[inline] |
| pub fn contains_key<Q>(&self, key: &Q) -> bool |
| where |
| K: Borrow<Q>, |
| Q: Ord + ?Sized, |
| { |
| self.get(key).is_some() |
| } |
| } |
| |
| impl<K: Ord, V> IntoIterator for SortedMap<K, V> { |
| type Item = (K, V); |
| type IntoIter = ::std::vec::IntoIter<(K, V)>; |
| |
| fn into_iter(self) -> Self::IntoIter { |
| self.data.into_iter() |
| } |
| } |
| |
| impl<'a, K, Q, V> Index<&'a Q> for SortedMap<K, V> |
| where |
| K: Ord + Borrow<Q>, |
| Q: Ord + ?Sized, |
| { |
| type Output = V; |
| |
| fn index(&self, key: &Q) -> &Self::Output { |
| self.get(key).expect("no entry found for key") |
| } |
| } |
| |
| impl<'a, K, Q, V> IndexMut<&'a Q> for SortedMap<K, V> |
| where |
| K: Ord + Borrow<Q>, |
| Q: Ord + ?Sized, |
| { |
| fn index_mut(&mut self, key: &Q) -> &mut Self::Output { |
| self.get_mut(key).expect("no entry found for key") |
| } |
| } |
| |
| impl<K: Ord, V> FromIterator<(K, V)> for SortedMap<K, V> { |
| fn from_iter<T: IntoIterator<Item = (K, V)>>(iter: T) -> Self { |
| let mut data: Vec<(K, V)> = iter.into_iter().collect(); |
| |
| data.sort_unstable_by(|&(ref k1, _), &(ref k2, _)| k1.cmp(k2)); |
| data.dedup_by(|&mut (ref k1, _), &mut (ref k2, _)| k1.cmp(k2) == Ordering::Equal); |
| |
| SortedMap { data } |
| } |
| } |
| |
| #[cfg(test)] |
| mod tests; |