Antonio Scandurra
a88b63d83c
Previously, when splicing an edit that deleted all transforms, we would leave the `FoldMap` empty, thus violating a bunch of downstream invariants and e.g. causing the `BufferRows` iterator to not return any buffer row. This commit ensures we always have at least one transform (an isomorphic one, specifically) and adds additional test coverage for the `FoldMap::buffer_rows` method by adding it to the randomized tests.
820 lines
26 KiB
Rust
820 lines
26 KiB
Rust
mod cursor;
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use arrayvec::ArrayVec;
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pub use cursor::Cursor;
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pub use cursor::FilterCursor;
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use std::{fmt, iter::FromIterator, ops::AddAssign, sync::Arc};
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#[cfg(test)]
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const TREE_BASE: usize = 2;
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#[cfg(not(test))]
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const TREE_BASE: usize = 6;
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pub trait Item: Clone + Eq + fmt::Debug {
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type Summary: for<'a> AddAssign<&'a Self::Summary> + Default + Clone + fmt::Debug;
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fn summary(&self) -> Self::Summary;
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}
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pub trait KeyedItem: Item {
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type Key: for<'a> Dimension<'a, Self::Summary> + Ord;
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fn key(&self) -> Self::Key;
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}
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pub trait Dimension<'a, Summary: Default>: 'a + Clone + fmt::Debug + Default {
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fn add_summary(&mut self, summary: &'a Summary);
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}
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impl<'a, T: Default> Dimension<'a, T> for () {
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fn add_summary(&mut self, _: &'a T) {}
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}
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#[derive(Copy, Clone, Eq, PartialEq)]
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pub enum SeekBias {
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Left,
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Right,
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}
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#[derive(Debug, Clone)]
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pub struct SumTree<T: Item>(Arc<Node<T>>);
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impl<T: Item> SumTree<T> {
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pub fn new() -> Self {
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SumTree(Arc::new(Node::Leaf {
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summary: T::Summary::default(),
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items: ArrayVec::new(),
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item_summaries: ArrayVec::new(),
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}))
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}
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pub fn from_item(item: T) -> Self {
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let mut tree = Self::new();
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tree.push(item);
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tree
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}
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pub fn items(&self) -> Vec<T> {
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let mut cursor = self.cursor::<(), ()>();
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cursor.descend_to_first_item(self, |_| true);
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cursor.cloned().collect()
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}
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pub fn cursor<'a, S, U>(&'a self) -> Cursor<T, S, U>
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where
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S: Dimension<'a, T::Summary>,
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U: Dimension<'a, T::Summary>,
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{
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Cursor::new(self)
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}
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pub fn filter<'a, F, U>(&'a self, filter_node: F) -> FilterCursor<F, T, U>
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where
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F: Fn(&T::Summary) -> bool,
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U: Dimension<'a, T::Summary>,
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{
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FilterCursor::new(self, filter_node)
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}
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#[allow(dead_code)]
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pub fn first(&self) -> Option<&T> {
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self.leftmost_leaf().0.items().first()
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}
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pub fn last(&self) -> Option<&T> {
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self.rightmost_leaf().0.items().last()
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}
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pub fn extent<'a, D: Dimension<'a, T::Summary>>(&'a self) -> D {
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let mut extent = D::default();
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match self.0.as_ref() {
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Node::Internal { summary, .. } | Node::Leaf { summary, .. } => {
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extent.add_summary(summary)
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}
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}
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extent
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}
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pub fn summary(&self) -> T::Summary {
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match self.0.as_ref() {
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Node::Internal { summary, .. } => summary.clone(),
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Node::Leaf { summary, .. } => summary.clone(),
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}
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}
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pub fn is_empty(&self) -> bool {
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match self.0.as_ref() {
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Node::Internal { .. } => false,
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Node::Leaf { items, .. } => items.is_empty(),
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}
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}
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pub fn extend<I>(&mut self, iter: I)
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where
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I: IntoIterator<Item = T>,
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{
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let mut leaf: Option<Node<T>> = None;
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for item in iter {
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if leaf.is_some() && leaf.as_ref().unwrap().items().len() == 2 * TREE_BASE {
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self.push_tree(SumTree(Arc::new(leaf.take().unwrap())));
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}
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if leaf.is_none() {
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leaf = Some(Node::Leaf::<T> {
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summary: T::Summary::default(),
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items: ArrayVec::new(),
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item_summaries: ArrayVec::new(),
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});
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}
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if let Some(Node::Leaf {
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summary,
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items,
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item_summaries,
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}) = leaf.as_mut()
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{
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let item_summary = item.summary();
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*summary += &item_summary;
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items.push(item);
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item_summaries.push(item_summary);
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} else {
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unreachable!()
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}
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}
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if leaf.is_some() {
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self.push_tree(SumTree(Arc::new(leaf.take().unwrap())));
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}
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}
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pub fn push(&mut self, item: T) {
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let summary = item.summary();
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self.push_tree(SumTree::from_child_trees(vec![SumTree(Arc::new(
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Node::Leaf {
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summary: summary.clone(),
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items: ArrayVec::from_iter(Some(item)),
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item_summaries: ArrayVec::from_iter(Some(summary)),
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},
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))]))
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}
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pub fn push_tree(&mut self, other: Self) {
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let other_node = other.0.clone();
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if !other_node.is_leaf() || other_node.items().len() > 0 {
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if self.0.height() < other_node.height() {
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for tree in other_node.child_trees() {
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self.push_tree(tree.clone());
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}
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} else if let Some(split_tree) = self.push_tree_recursive(other) {
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*self = Self::from_child_trees(vec![self.clone(), split_tree]);
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}
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}
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}
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fn push_tree_recursive(&mut self, other: SumTree<T>) -> Option<SumTree<T>> {
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match Arc::make_mut(&mut self.0) {
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Node::Internal {
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height,
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summary,
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child_summaries,
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child_trees,
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..
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} => {
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let other_node = other.0.clone();
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*summary += other_node.summary();
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let height_delta = *height - other_node.height();
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let mut summaries_to_append = ArrayVec::<[T::Summary; 2 * TREE_BASE]>::new();
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let mut trees_to_append = ArrayVec::<[SumTree<T>; 2 * TREE_BASE]>::new();
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if height_delta == 0 {
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summaries_to_append.extend(other_node.child_summaries().iter().cloned());
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trees_to_append.extend(other_node.child_trees().iter().cloned());
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} else if height_delta == 1 && !other_node.is_underflowing() {
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summaries_to_append.push(other_node.summary().clone());
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trees_to_append.push(other)
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} else {
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let tree_to_append = child_trees.last_mut().unwrap().push_tree_recursive(other);
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*child_summaries.last_mut().unwrap() =
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child_trees.last().unwrap().0.summary().clone();
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if let Some(split_tree) = tree_to_append {
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summaries_to_append.push(split_tree.0.summary().clone());
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trees_to_append.push(split_tree);
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}
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}
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let child_count = child_trees.len() + trees_to_append.len();
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if child_count > 2 * TREE_BASE {
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let left_summaries: ArrayVec<_>;
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let right_summaries: ArrayVec<_>;
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let left_trees;
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let right_trees;
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let midpoint = (child_count + child_count % 2) / 2;
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{
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let mut all_summaries = child_summaries
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.iter()
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.chain(summaries_to_append.iter())
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.cloned();
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left_summaries = all_summaries.by_ref().take(midpoint).collect();
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right_summaries = all_summaries.collect();
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let mut all_trees =
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child_trees.iter().chain(trees_to_append.iter()).cloned();
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left_trees = all_trees.by_ref().take(midpoint).collect();
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right_trees = all_trees.collect();
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}
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*summary = sum(left_summaries.iter());
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*child_summaries = left_summaries;
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*child_trees = left_trees;
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Some(SumTree(Arc::new(Node::Internal {
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height: *height,
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summary: sum(right_summaries.iter()),
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child_summaries: right_summaries,
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child_trees: right_trees,
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})))
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} else {
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child_summaries.extend(summaries_to_append);
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child_trees.extend(trees_to_append);
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None
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}
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}
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Node::Leaf {
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summary,
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items,
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item_summaries,
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} => {
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let other_node = other.0;
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let child_count = items.len() + other_node.items().len();
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if child_count > 2 * TREE_BASE {
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let left_items;
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let right_items;
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let left_summaries;
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let right_summaries: ArrayVec<[T::Summary; 2 * TREE_BASE]>;
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let midpoint = (child_count + child_count % 2) / 2;
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{
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let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
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left_items = all_items.by_ref().take(midpoint).collect();
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right_items = all_items.collect();
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let mut all_summaries = item_summaries
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.iter()
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.chain(other_node.child_summaries())
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.cloned();
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left_summaries = all_summaries.by_ref().take(midpoint).collect();
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right_summaries = all_summaries.collect();
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}
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*items = left_items;
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*item_summaries = left_summaries;
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*summary = sum(item_summaries.iter());
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Some(SumTree(Arc::new(Node::Leaf {
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items: right_items,
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summary: sum(right_summaries.iter()),
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item_summaries: right_summaries,
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})))
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} else {
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*summary += other_node.summary();
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items.extend(other_node.items().iter().cloned());
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item_summaries.extend(other_node.child_summaries().iter().cloned());
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None
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}
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}
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}
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}
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fn from_child_trees(child_trees: Vec<SumTree<T>>) -> Self {
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let height = child_trees[0].0.height() + 1;
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let mut child_summaries = ArrayVec::new();
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for child in &child_trees {
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child_summaries.push(child.0.summary().clone());
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}
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let summary = sum(child_summaries.iter());
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SumTree(Arc::new(Node::Internal {
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height,
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summary,
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child_summaries,
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child_trees: ArrayVec::from_iter(child_trees),
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}))
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}
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fn leftmost_leaf(&self) -> &Self {
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match *self.0 {
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Node::Leaf { .. } => self,
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Node::Internal {
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ref child_trees, ..
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} => child_trees.first().unwrap().leftmost_leaf(),
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}
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}
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fn rightmost_leaf(&self) -> &Self {
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match *self.0 {
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Node::Leaf { .. } => self,
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Node::Internal {
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ref child_trees, ..
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} => child_trees.last().unwrap().rightmost_leaf(),
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}
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}
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}
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impl<T: KeyedItem> SumTree<T> {
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pub fn insert(&mut self, item: T) {
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*self = {
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let mut cursor = self.cursor::<T::Key, ()>();
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let mut new_tree = cursor.slice(&item.key(), SeekBias::Left);
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new_tree.push(item);
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new_tree.push_tree(cursor.suffix());
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new_tree
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};
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}
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pub fn edit(&mut self, edits: &mut [Edit<T>]) {
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if edits.is_empty() {
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return;
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}
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edits.sort_unstable_by_key(|item| item.key());
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*self = {
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let mut cursor = self.cursor::<T::Key, ()>();
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let mut new_tree = SumTree::new();
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let mut buffered_items = Vec::new();
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cursor.seek(&T::Key::default(), SeekBias::Left);
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for edit in edits {
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let new_key = edit.key();
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let mut old_item = cursor.item();
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if old_item
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.as_ref()
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.map_or(false, |old_item| old_item.key() < new_key)
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{
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new_tree.extend(buffered_items.drain(..));
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let slice = cursor.slice(&new_key, SeekBias::Left);
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new_tree.push_tree(slice);
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old_item = cursor.item();
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}
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if old_item.map_or(false, |old_item| old_item.key() == new_key) {
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cursor.next();
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}
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match edit {
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Edit::Insert(item) => {
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buffered_items.push(item.clone());
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}
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Edit::Remove(_) => {}
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}
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}
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new_tree.extend(buffered_items);
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new_tree.push_tree(cursor.suffix());
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new_tree
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};
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}
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}
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#[derive(Clone, Debug)]
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pub enum Node<T: Item> {
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Internal {
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height: u8,
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summary: T::Summary,
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child_summaries: ArrayVec<[T::Summary; 2 * TREE_BASE]>,
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child_trees: ArrayVec<[SumTree<T>; 2 * TREE_BASE]>,
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},
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Leaf {
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summary: T::Summary,
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items: ArrayVec<[T; 2 * TREE_BASE]>,
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item_summaries: ArrayVec<[T::Summary; 2 * TREE_BASE]>,
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},
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}
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impl<T: Item> Node<T> {
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fn is_leaf(&self) -> bool {
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match self {
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Node::Leaf { .. } => true,
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_ => false,
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}
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}
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fn height(&self) -> u8 {
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match self {
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Node::Internal { height, .. } => *height,
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Node::Leaf { .. } => 0,
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}
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}
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fn summary(&self) -> &T::Summary {
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match self {
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Node::Internal { summary, .. } => summary,
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Node::Leaf { summary, .. } => summary,
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}
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}
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fn child_summaries(&self) -> &[T::Summary] {
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match self {
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Node::Internal {
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child_summaries, ..
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} => child_summaries.as_slice(),
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Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
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}
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}
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fn child_trees(&self) -> &ArrayVec<[SumTree<T>; 2 * TREE_BASE]> {
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match self {
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Node::Internal { child_trees, .. } => child_trees,
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Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
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}
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}
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fn items(&self) -> &ArrayVec<[T; 2 * TREE_BASE]> {
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match self {
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Node::Leaf { items, .. } => items,
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Node::Internal { .. } => panic!("Internal nodes have no items"),
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}
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}
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fn is_underflowing(&self) -> bool {
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match self {
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Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
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Node::Leaf { items, .. } => items.len() < TREE_BASE,
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}
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}
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}
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#[derive(Debug)]
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pub enum Edit<T: KeyedItem> {
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Insert(T),
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Remove(T),
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}
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impl<T: KeyedItem> Edit<T> {
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fn key(&self) -> T::Key {
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match self {
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Edit::Insert(item) | Edit::Remove(item) => item.key(),
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}
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}
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}
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fn sum<'a, T, I>(iter: I) -> T
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where
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T: 'a + Default + AddAssign<&'a T>,
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I: Iterator<Item = &'a T>,
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{
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let mut sum = T::default();
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for value in iter {
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sum += value;
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}
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sum
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use std::ops::Add;
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#[test]
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fn test_extend_and_push_tree() {
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let mut tree1 = SumTree::new();
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tree1.extend(0..20);
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let mut tree2 = SumTree::new();
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tree2.extend(50..100);
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tree1.push_tree(tree2);
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assert_eq!(tree1.items(), (0..20).chain(50..100).collect::<Vec<u8>>());
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}
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#[test]
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fn test_random() {
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for seed in 0..100 {
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use rand::{distributions, prelude::*};
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let rng = &mut StdRng::seed_from_u64(seed);
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let mut tree = SumTree::<u8>::new();
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let count = rng.gen_range(0..10);
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tree.extend(rng.sample_iter(distributions::Standard).take(count));
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for _ in 0..5 {
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let splice_end = rng.gen_range(0..tree.extent::<Count>().0 + 1);
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let splice_start = rng.gen_range(0..splice_end + 1);
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let count = rng.gen_range(0..3);
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let tree_end = tree.extent::<Count>();
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let new_items = rng
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.sample_iter(distributions::Standard)
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.take(count)
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.collect::<Vec<u8>>();
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let mut reference_items = tree.items();
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reference_items.splice(splice_start..splice_end, new_items.clone());
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tree = {
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let mut cursor = tree.cursor::<Count, ()>();
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let mut new_tree = cursor.slice(&Count(splice_start), SeekBias::Right);
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new_tree.extend(new_items);
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cursor.seek(&Count(splice_end), SeekBias::Right);
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new_tree.push_tree(cursor.slice(&tree_end, SeekBias::Right));
|
|
new_tree
|
|
};
|
|
|
|
assert_eq!(tree.items(), reference_items);
|
|
|
|
let mut filter_cursor = tree.filter::<_, Count>(|summary| summary.contains_even);
|
|
let mut reference_filter = tree
|
|
.items()
|
|
.into_iter()
|
|
.enumerate()
|
|
.filter(|(_, item)| (item & 1) == 0);
|
|
while let Some(actual_item) = filter_cursor.item() {
|
|
let (reference_index, reference_item) = reference_filter.next().unwrap();
|
|
assert_eq!(actual_item, &reference_item);
|
|
assert_eq!(filter_cursor.start().0, reference_index);
|
|
filter_cursor.next();
|
|
}
|
|
assert!(reference_filter.next().is_none());
|
|
|
|
let mut pos = rng.gen_range(0..tree.extent::<Count>().0 + 1);
|
|
let mut before_start = false;
|
|
let mut cursor = tree.cursor::<Count, Count>();
|
|
cursor.seek(&Count(pos), SeekBias::Right);
|
|
|
|
for i in 0..10 {
|
|
assert_eq!(cursor.start().0, pos);
|
|
|
|
if pos > 0 {
|
|
assert_eq!(cursor.prev_item().unwrap(), &reference_items[pos - 1]);
|
|
} else {
|
|
assert_eq!(cursor.prev_item(), None);
|
|
}
|
|
|
|
if pos < reference_items.len() && !before_start {
|
|
assert_eq!(cursor.item().unwrap(), &reference_items[pos]);
|
|
} else {
|
|
assert_eq!(cursor.item(), None);
|
|
}
|
|
|
|
if i < 5 {
|
|
cursor.next();
|
|
if pos < reference_items.len() {
|
|
pos += 1;
|
|
before_start = false;
|
|
}
|
|
} else {
|
|
cursor.prev();
|
|
if pos == 0 {
|
|
before_start = true;
|
|
}
|
|
pos = pos.saturating_sub(1);
|
|
}
|
|
}
|
|
}
|
|
|
|
for _ in 0..10 {
|
|
let end = rng.gen_range(0..tree.extent::<Count>().0 + 1);
|
|
let start = rng.gen_range(0..end + 1);
|
|
let start_bias = if rng.gen() {
|
|
SeekBias::Left
|
|
} else {
|
|
SeekBias::Right
|
|
};
|
|
let end_bias = if rng.gen() {
|
|
SeekBias::Left
|
|
} else {
|
|
SeekBias::Right
|
|
};
|
|
|
|
let mut cursor = tree.cursor::<Count, ()>();
|
|
cursor.seek(&Count(start), start_bias);
|
|
let slice = cursor.slice(&Count(end), end_bias);
|
|
|
|
cursor.seek(&Count(start), start_bias);
|
|
let summary = cursor.summary::<Sum>(&Count(end), end_bias);
|
|
|
|
assert_eq!(summary, slice.summary().sum);
|
|
}
|
|
}
|
|
}
|
|
|
|
#[test]
|
|
fn test_cursor() {
|
|
// Empty tree
|
|
let tree = SumTree::<u8>::new();
|
|
let mut cursor = tree.cursor::<Count, Sum>();
|
|
assert_eq!(
|
|
cursor.slice(&Count(0), SeekBias::Right).items(),
|
|
Vec::<u8>::new()
|
|
);
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), None);
|
|
assert_eq!(cursor.start(), &Sum(0));
|
|
|
|
// Single-element tree
|
|
let mut tree = SumTree::<u8>::new();
|
|
tree.extend(vec![1]);
|
|
let mut cursor = tree.cursor::<Count, Sum>();
|
|
assert_eq!(
|
|
cursor.slice(&Count(0), SeekBias::Right).items(),
|
|
Vec::<u8>::new()
|
|
);
|
|
assert_eq!(cursor.item(), Some(&1));
|
|
assert_eq!(cursor.prev_item(), None);
|
|
assert_eq!(cursor.start(), &Sum(0));
|
|
|
|
cursor.next();
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), Some(&1));
|
|
assert_eq!(cursor.start(), &Sum(1));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&1));
|
|
assert_eq!(cursor.prev_item(), None);
|
|
assert_eq!(cursor.start(), &Sum(0));
|
|
|
|
let mut cursor = tree.cursor::<Count, Sum>();
|
|
assert_eq!(cursor.slice(&Count(1), SeekBias::Right).items(), [1]);
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), Some(&1));
|
|
assert_eq!(cursor.start(), &Sum(1));
|
|
|
|
cursor.seek(&Count(0), SeekBias::Right);
|
|
assert_eq!(
|
|
cursor
|
|
.slice(&tree.extent::<Count>(), SeekBias::Right)
|
|
.items(),
|
|
[1]
|
|
);
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), Some(&1));
|
|
assert_eq!(cursor.start(), &Sum(1));
|
|
|
|
// Multiple-element tree
|
|
let mut tree = SumTree::new();
|
|
tree.extend(vec![1, 2, 3, 4, 5, 6]);
|
|
let mut cursor = tree.cursor::<Count, Sum>();
|
|
|
|
assert_eq!(cursor.slice(&Count(2), SeekBias::Right).items(), [1, 2]);
|
|
assert_eq!(cursor.item(), Some(&3));
|
|
assert_eq!(cursor.prev_item(), Some(&2));
|
|
assert_eq!(cursor.start(), &Sum(3));
|
|
|
|
cursor.next();
|
|
assert_eq!(cursor.item(), Some(&4));
|
|
assert_eq!(cursor.prev_item(), Some(&3));
|
|
assert_eq!(cursor.start(), &Sum(6));
|
|
|
|
cursor.next();
|
|
assert_eq!(cursor.item(), Some(&5));
|
|
assert_eq!(cursor.prev_item(), Some(&4));
|
|
assert_eq!(cursor.start(), &Sum(10));
|
|
|
|
cursor.next();
|
|
assert_eq!(cursor.item(), Some(&6));
|
|
assert_eq!(cursor.prev_item(), Some(&5));
|
|
assert_eq!(cursor.start(), &Sum(15));
|
|
|
|
cursor.next();
|
|
cursor.next();
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), Some(&6));
|
|
assert_eq!(cursor.start(), &Sum(21));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&6));
|
|
assert_eq!(cursor.prev_item(), Some(&5));
|
|
assert_eq!(cursor.start(), &Sum(15));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&5));
|
|
assert_eq!(cursor.prev_item(), Some(&4));
|
|
assert_eq!(cursor.start(), &Sum(10));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&4));
|
|
assert_eq!(cursor.prev_item(), Some(&3));
|
|
assert_eq!(cursor.start(), &Sum(6));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&3));
|
|
assert_eq!(cursor.prev_item(), Some(&2));
|
|
assert_eq!(cursor.start(), &Sum(3));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&2));
|
|
assert_eq!(cursor.prev_item(), Some(&1));
|
|
assert_eq!(cursor.start(), &Sum(1));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), Some(&1));
|
|
assert_eq!(cursor.prev_item(), None);
|
|
assert_eq!(cursor.start(), &Sum(0));
|
|
|
|
cursor.prev();
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), None);
|
|
assert_eq!(cursor.start(), &Sum(0));
|
|
|
|
cursor.next();
|
|
assert_eq!(cursor.item(), Some(&1));
|
|
assert_eq!(cursor.prev_item(), None);
|
|
assert_eq!(cursor.start(), &Sum(0));
|
|
|
|
let mut cursor = tree.cursor::<Count, Sum>();
|
|
assert_eq!(
|
|
cursor
|
|
.slice(&tree.extent::<Count>(), SeekBias::Right)
|
|
.items(),
|
|
tree.items()
|
|
);
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), Some(&6));
|
|
assert_eq!(cursor.start(), &Sum(21));
|
|
|
|
cursor.seek(&Count(3), SeekBias::Right);
|
|
assert_eq!(
|
|
cursor
|
|
.slice(&tree.extent::<Count>(), SeekBias::Right)
|
|
.items(),
|
|
[4, 5, 6]
|
|
);
|
|
assert_eq!(cursor.item(), None);
|
|
assert_eq!(cursor.prev_item(), Some(&6));
|
|
assert_eq!(cursor.start(), &Sum(21));
|
|
|
|
// Seeking can bias left or right
|
|
cursor.seek(&Count(1), SeekBias::Left);
|
|
assert_eq!(cursor.item(), Some(&1));
|
|
cursor.seek(&Count(1), SeekBias::Right);
|
|
assert_eq!(cursor.item(), Some(&2));
|
|
|
|
// Slicing without resetting starts from where the cursor is parked at.
|
|
cursor.seek(&Count(1), SeekBias::Right);
|
|
assert_eq!(cursor.slice(&Count(3), SeekBias::Right).items(), vec![2, 3]);
|
|
assert_eq!(cursor.slice(&Count(6), SeekBias::Left).items(), vec![4, 5]);
|
|
assert_eq!(cursor.slice(&Count(6), SeekBias::Right).items(), vec![6]);
|
|
}
|
|
|
|
#[derive(Clone, Default, Debug)]
|
|
pub struct IntegersSummary {
|
|
count: Count,
|
|
sum: Sum,
|
|
contains_even: bool,
|
|
}
|
|
|
|
#[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
|
|
struct Count(usize);
|
|
|
|
#[derive(Ord, PartialOrd, Default, Eq, PartialEq, Clone, Debug)]
|
|
struct Sum(usize);
|
|
|
|
impl Item for u8 {
|
|
type Summary = IntegersSummary;
|
|
|
|
fn summary(&self) -> Self::Summary {
|
|
IntegersSummary {
|
|
count: Count(1),
|
|
sum: Sum(*self as usize),
|
|
contains_even: (*self & 1) == 0,
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<'a> AddAssign<&'a Self> for IntegersSummary {
|
|
fn add_assign(&mut self, other: &Self) {
|
|
self.count.0 += &other.count.0;
|
|
self.sum.0 += &other.sum.0;
|
|
self.contains_even |= other.contains_even;
|
|
}
|
|
}
|
|
|
|
impl<'a> Dimension<'a, IntegersSummary> for Count {
|
|
fn add_summary(&mut self, summary: &IntegersSummary) {
|
|
self.0 += summary.count.0;
|
|
}
|
|
}
|
|
|
|
// impl<'a> Add<&'a Self> for Count {
|
|
// type Output = Self;
|
|
//
|
|
// fn add(mut self, other: &Self) -> Self {
|
|
// self.0 += other.0;
|
|
// self
|
|
// }
|
|
// }
|
|
|
|
impl<'a> Dimension<'a, IntegersSummary> for Sum {
|
|
fn add_summary(&mut self, summary: &IntegersSummary) {
|
|
self.0 += summary.sum.0;
|
|
}
|
|
}
|
|
|
|
impl<'a> Add<&'a Self> for Sum {
|
|
type Output = Self;
|
|
|
|
fn add(mut self, other: &Self) -> Self {
|
|
self.0 += other.0;
|
|
self
|
|
}
|
|
}
|
|
}
|