WIP
This commit is contained in:
Nathan Sobo
@@ -0,0 +1,752 @@
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use super::*;
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use arrayvec::ArrayVec;
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use std::{cmp::Ordering, sync::Arc};
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#[derive(Clone)]
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struct StackEntry<'a, T: Item, S, U> {
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tree: &'a SumTree<T>,
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index: usize,
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seek_dimension: S,
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sum_dimension: U,
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}
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#[derive(Clone)]
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pub struct Cursor<'a, T: Item, S, U> {
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tree: &'a SumTree<T>,
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stack: ArrayVec<[StackEntry<'a, T, S, U>; 16]>,
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seek_dimension: S,
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sum_dimension: U,
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did_seek: bool,
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at_end: bool,
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}
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impl<'a, T, S, U> Cursor<'a, T, S, U>
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where
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T: Item,
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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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pub fn new(tree: &'a SumTree<T>) -> Self {
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Self {
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tree,
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stack: ArrayVec::new(),
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seek_dimension: S::default(),
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sum_dimension: U::default(),
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did_seek: false,
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at_end: false,
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}
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}
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fn reset(&mut self) {
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self.did_seek = false;
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self.at_end = false;
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self.stack.truncate(0);
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self.seek_dimension = S::default();
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self.sum_dimension = U::default();
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}
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pub fn start(&self) -> &U {
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&self.sum_dimension
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}
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pub fn end(&self) -> U {
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if let Some(item_summary) = self.item_summary() {
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let mut end = self.start().clone();
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end.add_summary(item_summary);
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end
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} else {
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self.start().clone()
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}
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}
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pub fn item(&self) -> Option<&'a T> {
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assert!(self.did_seek, "Must seek before calling this method");
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if let Some(entry) = self.stack.last() {
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match *entry.tree.0 {
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Node::Leaf { ref items, .. } => {
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if entry.index == items.len() {
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None
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} else {
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Some(&items[entry.index])
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}
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}
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_ => unreachable!(),
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}
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} else {
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None
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}
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}
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fn item_summary(&self) -> Option<&'a T::Summary> {
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assert!(self.did_seek, "Must seek before calling this method");
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if let Some(entry) = self.stack.last() {
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match *entry.tree.0 {
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Node::Leaf {
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ref item_summaries, ..
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} => {
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if entry.index == item_summaries.len() {
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None
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} else {
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Some(&item_summaries[entry.index])
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}
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}
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_ => unreachable!(),
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}
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} else {
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None
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}
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}
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pub fn prev_item(&self) -> Option<&'a T> {
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assert!(self.did_seek, "Must seek before calling this method");
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if let Some(entry) = self.stack.last() {
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if entry.index == 0 {
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if let Some(prev_leaf) = self.prev_leaf() {
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Some(prev_leaf.0.items().last().unwrap())
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} else {
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None
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}
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} else {
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match *entry.tree.0 {
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Node::Leaf { ref items, .. } => Some(&items[entry.index - 1]),
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_ => unreachable!(),
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}
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}
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} else if self.at_end {
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self.tree.last()
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} else {
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None
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}
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}
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fn prev_leaf(&self) -> Option<&'a SumTree<T>> {
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for entry in self.stack.iter().rev().skip(1) {
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if entry.index != 0 {
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match *entry.tree.0 {
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Node::Internal {
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ref child_trees, ..
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} => return Some(child_trees[entry.index - 1].rightmost_leaf()),
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Node::Leaf { .. } => unreachable!(),
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};
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}
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}
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None
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}
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pub fn prev(&mut self) {
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assert!(self.did_seek, "Must seek before calling this method");
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if self.at_end {
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self.seek_dimension = S::default();
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self.sum_dimension = U::default();
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self.descend_to_last_item(self.tree);
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self.at_end = false;
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} else {
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while let Some(entry) = self.stack.pop() {
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if entry.index > 0 {
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let new_index = entry.index - 1;
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if let Some(StackEntry {
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seek_dimension,
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sum_dimension,
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..
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}) = self.stack.last()
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{
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self.seek_dimension = seek_dimension.clone();
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self.sum_dimension = sum_dimension.clone();
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} else {
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self.seek_dimension = S::default();
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self.sum_dimension = U::default();
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}
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match entry.tree.0.as_ref() {
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Node::Internal {
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child_trees,
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child_summaries,
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..
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} => {
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for summary in &child_summaries[0..new_index] {
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self.seek_dimension.add_summary(summary);
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self.sum_dimension.add_summary(summary);
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}
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self.stack.push(StackEntry {
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tree: entry.tree,
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index: new_index,
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seek_dimension: self.seek_dimension.clone(),
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sum_dimension: self.sum_dimension.clone(),
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});
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self.descend_to_last_item(&child_trees[new_index]);
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}
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Node::Leaf { item_summaries, .. } => {
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for item_summary in &item_summaries[0..new_index] {
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self.seek_dimension.add_summary(item_summary);
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self.sum_dimension.add_summary(item_summary);
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}
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self.stack.push(StackEntry {
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tree: entry.tree,
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index: new_index,
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seek_dimension: self.seek_dimension.clone(),
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sum_dimension: self.sum_dimension.clone(),
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});
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}
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}
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break;
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}
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}
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}
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}
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pub fn next(&mut self) {
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self.next_internal(|_| true)
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}
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fn next_internal<F>(&mut self, filter_node: F)
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where
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F: Fn(&T::Summary) -> bool,
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{
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assert!(self.did_seek, "Must seek before calling this method");
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if self.stack.is_empty() {
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if !self.at_end {
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self.descend_to_first_item(self.tree, filter_node);
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}
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} else {
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while self.stack.len() > 0 {
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let new_subtree = {
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let entry = self.stack.last_mut().unwrap();
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match entry.tree.0.as_ref() {
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Node::Internal {
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child_trees,
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child_summaries,
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..
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} => {
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while entry.index < child_summaries.len() {
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entry
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.seek_dimension
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.add_summary(&child_summaries[entry.index]);
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entry
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.sum_dimension
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.add_summary(&child_summaries[entry.index]);
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entry.index += 1;
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if let Some(next_summary) = child_summaries.get(entry.index) {
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if filter_node(next_summary) {
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break;
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} else {
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self.seek_dimension.add_summary(next_summary);
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self.sum_dimension.add_summary(next_summary);
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}
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}
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}
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child_trees.get(entry.index)
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}
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Node::Leaf { item_summaries, .. } => loop {
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let item_summary = &item_summaries[entry.index];
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self.seek_dimension.add_summary(item_summary);
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entry.seek_dimension.add_summary(item_summary);
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self.sum_dimension.add_summary(item_summary);
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entry.sum_dimension.add_summary(item_summary);
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entry.index += 1;
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if let Some(next_item_summary) = item_summaries.get(entry.index) {
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if filter_node(next_item_summary) {
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return;
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}
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} else {
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break None;
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}
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},
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}
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};
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if let Some(subtree) = new_subtree {
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self.descend_to_first_item(subtree, filter_node);
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break;
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} else {
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self.stack.pop();
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}
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}
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}
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self.at_end = self.stack.is_empty();
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}
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pub fn descend_to_first_item<F>(&mut self, mut subtree: &'a SumTree<T>, filter_node: F)
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where
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F: Fn(&T::Summary) -> bool,
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{
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self.did_seek = true;
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loop {
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subtree = match *subtree.0 {
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Node::Internal {
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ref child_trees,
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ref child_summaries,
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..
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} => {
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let mut new_index = None;
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for (index, summary) in child_summaries.iter().enumerate() {
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if filter_node(summary) {
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new_index = Some(index);
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break;
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}
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self.seek_dimension.add_summary(summary);
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self.sum_dimension.add_summary(summary);
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}
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if let Some(new_index) = new_index {
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self.stack.push(StackEntry {
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tree: subtree,
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index: new_index,
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seek_dimension: self.seek_dimension.clone(),
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sum_dimension: self.sum_dimension.clone(),
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});
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&child_trees[new_index]
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} else {
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break;
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}
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}
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Node::Leaf {
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ref item_summaries, ..
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} => {
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let mut new_index = None;
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for (index, item_summary) in item_summaries.iter().enumerate() {
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if filter_node(item_summary) {
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new_index = Some(index);
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break;
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}
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self.seek_dimension.add_summary(item_summary);
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self.sum_dimension.add_summary(item_summary);
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}
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if let Some(new_index) = new_index {
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self.stack.push(StackEntry {
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tree: subtree,
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index: new_index,
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seek_dimension: self.seek_dimension.clone(),
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sum_dimension: self.sum_dimension.clone(),
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});
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}
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break;
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}
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}
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}
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}
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fn descend_to_last_item(&mut self, mut subtree: &'a SumTree<T>) {
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self.did_seek = true;
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loop {
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match subtree.0.as_ref() {
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Node::Internal {
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child_trees,
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child_summaries,
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..
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} => {
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for summary in &child_summaries[0..child_summaries.len() - 1] {
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self.seek_dimension.add_summary(summary);
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self.sum_dimension.add_summary(summary);
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}
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self.stack.push(StackEntry {
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tree: subtree,
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index: child_trees.len() - 1,
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seek_dimension: self.seek_dimension.clone(),
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sum_dimension: self.sum_dimension.clone(),
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});
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subtree = child_trees.last().unwrap();
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}
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Node::Leaf { item_summaries, .. } => {
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let last_index = item_summaries.len().saturating_sub(1);
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for item_summary in &item_summaries[0..last_index] {
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self.seek_dimension.add_summary(item_summary);
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self.sum_dimension.add_summary(item_summary);
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}
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self.stack.push(StackEntry {
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tree: subtree,
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index: last_index,
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seek_dimension: self.seek_dimension.clone(),
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sum_dimension: self.sum_dimension.clone(),
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});
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break;
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}
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}
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}
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}
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}
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impl<'a, T, S, U> Cursor<'a, T, S, U>
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where
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T: Item,
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S: Dimension<'a, T::Summary> + Ord,
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U: Dimension<'a, T::Summary>,
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{
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pub fn seek(&mut self, pos: &S, bias: SeekBias) -> bool {
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self.reset();
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self.seek_internal::<()>(pos, bias, &mut SeekAggregate::None)
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}
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pub fn seek_forward(&mut self, pos: &S, bias: SeekBias) -> bool {
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self.seek_internal::<()>(pos, bias, &mut SeekAggregate::None)
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}
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pub fn slice(&mut self, end: &S, bias: SeekBias) -> SumTree<T> {
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let mut slice = SeekAggregate::Slice(SumTree::new());
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self.seek_internal::<()>(end, bias, &mut slice);
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if let SeekAggregate::Slice(slice) = slice {
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slice
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} else {
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unreachable!()
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}
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}
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pub fn suffix(&mut self) -> SumTree<T> {
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let extent = self.tree.extent::<S>();
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let mut slice = SeekAggregate::Slice(SumTree::new());
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self.seek_internal::<()>(&extent, SeekBias::Right, &mut slice);
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if let SeekAggregate::Slice(slice) = slice {
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slice
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} else {
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unreachable!()
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}
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}
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pub fn summary<D>(&mut self, end: &S, bias: SeekBias) -> D
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where
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D: Dimension<'a, T::Summary>,
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{
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let mut summary = SeekAggregate::Summary(D::default());
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self.seek_internal(end, bias, &mut summary);
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if let SeekAggregate::Summary(summary) = summary {
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summary
|
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} else {
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unreachable!()
|
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}
|
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}
|
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fn seek_internal<D>(
|
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&mut self,
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target: &S,
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bias: SeekBias,
|
||||
aggregate: &mut SeekAggregate<T, D>,
|
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) -> bool
|
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where
|
||||
D: Dimension<'a, T::Summary>,
|
||||
{
|
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debug_assert!(target >= &self.seek_dimension);
|
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let mut containing_subtree = None;
|
||||
|
||||
if self.did_seek {
|
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'outer: while let Some(entry) = self.stack.last_mut() {
|
||||
{
|
||||
match *entry.tree.0 {
|
||||
Node::Internal {
|
||||
ref child_summaries,
|
||||
ref child_trees,
|
||||
..
|
||||
} => {
|
||||
entry.index += 1;
|
||||
for (child_tree, child_summary) in child_trees[entry.index..]
|
||||
.iter()
|
||||
.zip(&child_summaries[entry.index..])
|
||||
{
|
||||
let mut child_end = self.seek_dimension.clone();
|
||||
child_end.add_summary(&child_summary);
|
||||
|
||||
let comparison = target.cmp(&child_end);
|
||||
if comparison == Ordering::Greater
|
||||
|| (comparison == Ordering::Equal && bias == SeekBias::Right)
|
||||
{
|
||||
self.seek_dimension.add_summary(child_summary);
|
||||
self.sum_dimension.add_summary(child_summary);
|
||||
match aggregate {
|
||||
SeekAggregate::None => {}
|
||||
SeekAggregate::Slice(slice) => {
|
||||
slice.push_tree(child_tree.clone());
|
||||
}
|
||||
SeekAggregate::Summary(summary) => {
|
||||
summary.add_summary(child_summary);
|
||||
}
|
||||
}
|
||||
entry.index += 1;
|
||||
} else {
|
||||
containing_subtree = Some(child_tree);
|
||||
break 'outer;
|
||||
}
|
||||
}
|
||||
}
|
||||
Node::Leaf {
|
||||
ref items,
|
||||
ref item_summaries,
|
||||
..
|
||||
} => {
|
||||
let mut slice_items = ArrayVec::<[T; 2 * TREE_BASE]>::new();
|
||||
let mut slice_item_summaries =
|
||||
ArrayVec::<[T::Summary; 2 * TREE_BASE]>::new();
|
||||
let mut slice_items_summary = match aggregate {
|
||||
SeekAggregate::Slice(_) => Some(T::Summary::default()),
|
||||
_ => None,
|
||||
};
|
||||
|
||||
for (item, item_summary) in items[entry.index..]
|
||||
.iter()
|
||||
.zip(&item_summaries[entry.index..])
|
||||
{
|
||||
let mut item_end = self.seek_dimension.clone();
|
||||
item_end.add_summary(item_summary);
|
||||
|
||||
let comparison = target.cmp(&item_end);
|
||||
if comparison == Ordering::Greater
|
||||
|| (comparison == Ordering::Equal && bias == SeekBias::Right)
|
||||
{
|
||||
self.seek_dimension.add_summary(item_summary);
|
||||
self.sum_dimension.add_summary(item_summary);
|
||||
match aggregate {
|
||||
SeekAggregate::None => {}
|
||||
SeekAggregate::Slice(_) => {
|
||||
slice_items.push(item.clone());
|
||||
slice_item_summaries.push(item_summary.clone());
|
||||
*slice_items_summary.as_mut().unwrap() += item_summary;
|
||||
}
|
||||
SeekAggregate::Summary(summary) => {
|
||||
summary.add_summary(item_summary);
|
||||
}
|
||||
}
|
||||
entry.index += 1;
|
||||
} else {
|
||||
if let SeekAggregate::Slice(slice) = aggregate {
|
||||
slice.push_tree(SumTree(Arc::new(Node::Leaf {
|
||||
summary: slice_items_summary.unwrap(),
|
||||
items: slice_items,
|
||||
item_summaries: slice_item_summaries,
|
||||
})));
|
||||
}
|
||||
break 'outer;
|
||||
}
|
||||
}
|
||||
|
||||
if let SeekAggregate::Slice(slice) = aggregate {
|
||||
if !slice_items.is_empty() {
|
||||
slice.push_tree(SumTree(Arc::new(Node::Leaf {
|
||||
summary: slice_items_summary.unwrap(),
|
||||
items: slice_items,
|
||||
item_summaries: slice_item_summaries,
|
||||
})));
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
self.stack.pop();
|
||||
}
|
||||
} else {
|
||||
self.did_seek = true;
|
||||
containing_subtree = Some(self.tree);
|
||||
}
|
||||
|
||||
if let Some(mut subtree) = containing_subtree {
|
||||
loop {
|
||||
let mut next_subtree = None;
|
||||
match *subtree.0 {
|
||||
Node::Internal {
|
||||
ref child_summaries,
|
||||
ref child_trees,
|
||||
..
|
||||
} => {
|
||||
for (index, (child_tree, child_summary)) in
|
||||
child_trees.iter().zip(child_summaries).enumerate()
|
||||
{
|
||||
let mut child_end = self.seek_dimension.clone();
|
||||
child_end.add_summary(child_summary);
|
||||
|
||||
let comparison = target.cmp(&child_end);
|
||||
if comparison == Ordering::Greater
|
||||
|| (comparison == Ordering::Equal && bias == SeekBias::Right)
|
||||
{
|
||||
self.seek_dimension.add_summary(child_summary);
|
||||
self.sum_dimension.add_summary(child_summary);
|
||||
match aggregate {
|
||||
SeekAggregate::None => {}
|
||||
SeekAggregate::Slice(slice) => {
|
||||
slice.push_tree(child_trees[index].clone());
|
||||
}
|
||||
SeekAggregate::Summary(summary) => {
|
||||
summary.add_summary(child_summary);
|
||||
}
|
||||
}
|
||||
} else {
|
||||
self.stack.push(StackEntry {
|
||||
tree: subtree,
|
||||
index,
|
||||
seek_dimension: self.seek_dimension.clone(),
|
||||
sum_dimension: self.sum_dimension.clone(),
|
||||
});
|
||||
next_subtree = Some(child_tree);
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
Node::Leaf {
|
||||
ref items,
|
||||
ref item_summaries,
|
||||
..
|
||||
} => {
|
||||
let mut slice_items = ArrayVec::<[T; 2 * TREE_BASE]>::new();
|
||||
let mut slice_item_summaries =
|
||||
ArrayVec::<[T::Summary; 2 * TREE_BASE]>::new();
|
||||
let mut slice_items_summary = match aggregate {
|
||||
SeekAggregate::Slice(_) => Some(T::Summary::default()),
|
||||
_ => None,
|
||||
};
|
||||
|
||||
for (index, (item, item_summary)) in
|
||||
items.iter().zip(item_summaries).enumerate()
|
||||
{
|
||||
let mut child_end = self.seek_dimension.clone();
|
||||
child_end.add_summary(item_summary);
|
||||
|
||||
let comparison = target.cmp(&child_end);
|
||||
if comparison == Ordering::Greater
|
||||
|| (comparison == Ordering::Equal && bias == SeekBias::Right)
|
||||
{
|
||||
self.seek_dimension.add_summary(item_summary);
|
||||
self.sum_dimension.add_summary(item_summary);
|
||||
match aggregate {
|
||||
SeekAggregate::None => {}
|
||||
SeekAggregate::Slice(_) => {
|
||||
slice_items.push(item.clone());
|
||||
*slice_items_summary.as_mut().unwrap() += item_summary;
|
||||
slice_item_summaries.push(item_summary.clone());
|
||||
}
|
||||
SeekAggregate::Summary(summary) => {
|
||||
summary.add_summary(item_summary);
|
||||
}
|
||||
}
|
||||
} else {
|
||||
self.stack.push(StackEntry {
|
||||
tree: subtree,
|
||||
index,
|
||||
seek_dimension: self.seek_dimension.clone(),
|
||||
sum_dimension: self.sum_dimension.clone(),
|
||||
});
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
if let SeekAggregate::Slice(slice) = aggregate {
|
||||
if !slice_items.is_empty() {
|
||||
slice.push_tree(SumTree(Arc::new(Node::Leaf {
|
||||
summary: slice_items_summary.unwrap(),
|
||||
items: slice_items,
|
||||
item_summaries: slice_item_summaries,
|
||||
})));
|
||||
}
|
||||
}
|
||||
}
|
||||
};
|
||||
|
||||
if let Some(next_subtree) = next_subtree {
|
||||
subtree = next_subtree;
|
||||
} else {
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
self.at_end = self.stack.is_empty();
|
||||
if bias == SeekBias::Left {
|
||||
let mut end = self.seek_dimension.clone();
|
||||
if let Some(summary) = self.item_summary() {
|
||||
end.add_summary(summary);
|
||||
}
|
||||
*target == end
|
||||
} else {
|
||||
*target == self.seek_dimension
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a, T, S, U> Iterator for Cursor<'a, T, S, U>
|
||||
where
|
||||
T: Item,
|
||||
S: Dimension<'a, T::Summary>,
|
||||
U: Dimension<'a, T::Summary>,
|
||||
{
|
||||
type Item = &'a T;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
if !self.did_seek {
|
||||
self.descend_to_first_item(self.tree, |_| true);
|
||||
}
|
||||
|
||||
if let Some(item) = self.item() {
|
||||
self.next();
|
||||
Some(item)
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub struct FilterCursor<'a, F: Fn(&T::Summary) -> bool, T: Item, U> {
|
||||
cursor: Cursor<'a, T, (), U>,
|
||||
filter_node: F,
|
||||
}
|
||||
|
||||
impl<'a, F, T, U> FilterCursor<'a, F, T, U>
|
||||
where
|
||||
F: Fn(&T::Summary) -> bool,
|
||||
T: Item,
|
||||
U: Dimension<'a, T::Summary>,
|
||||
{
|
||||
pub fn new(tree: &'a SumTree<T>, filter_node: F) -> Self {
|
||||
let mut cursor = tree.cursor::<(), U>();
|
||||
if filter_node(&tree.summary()) {
|
||||
cursor.descend_to_first_item(tree, &filter_node);
|
||||
} else {
|
||||
cursor.did_seek = true;
|
||||
cursor.at_end = true;
|
||||
}
|
||||
|
||||
Self {
|
||||
cursor,
|
||||
filter_node,
|
||||
}
|
||||
}
|
||||
|
||||
pub fn start(&self) -> &U {
|
||||
self.cursor.start()
|
||||
}
|
||||
|
||||
pub fn item(&self) -> Option<&'a T> {
|
||||
self.cursor.item()
|
||||
}
|
||||
|
||||
pub fn next(&mut self) {
|
||||
self.cursor.next_internal(&self.filter_node);
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a, F, T, U> Iterator for FilterCursor<'a, F, T, U>
|
||||
where
|
||||
F: Fn(&T::Summary) -> bool,
|
||||
T: Item,
|
||||
U: Dimension<'a, T::Summary>,
|
||||
{
|
||||
type Item = &'a T;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
||||
if let Some(item) = self.item() {
|
||||
self.cursor.next_internal(&self.filter_node);
|
||||
Some(item)
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
enum SeekAggregate<T: Item, D> {
|
||||
None,
|
||||
Slice(SumTree<T>),
|
||||
Summary(D),
|
||||
}
|
||||
@@ -0,0 +1,820 @@
|
||||
mod cursor;
|
||||
|
||||
use arrayvec::ArrayVec;
|
||||
pub use cursor::Cursor;
|
||||
pub use cursor::FilterCursor;
|
||||
use std::{fmt, iter::FromIterator, ops::AddAssign, sync::Arc};
|
||||
|
||||
#[cfg(test)]
|
||||
const TREE_BASE: usize = 2;
|
||||
#[cfg(not(test))]
|
||||
const TREE_BASE: usize = 6;
|
||||
|
||||
pub trait Item: Clone + Eq + fmt::Debug {
|
||||
type Summary: for<'a> AddAssign<&'a Self::Summary> + Default + Clone + fmt::Debug;
|
||||
|
||||
fn summary(&self) -> Self::Summary;
|
||||
}
|
||||
|
||||
pub trait KeyedItem: Item {
|
||||
type Key: for<'a> Dimension<'a, Self::Summary> + Ord;
|
||||
|
||||
fn key(&self) -> Self::Key;
|
||||
}
|
||||
|
||||
pub trait Dimension<'a, Summary: Default>: 'a + Clone + fmt::Debug + Default {
|
||||
fn add_summary(&mut self, summary: &'a Summary);
|
||||
}
|
||||
|
||||
impl<'a, T: Default> Dimension<'a, T> for () {
|
||||
fn add_summary(&mut self, _: &'a T) {}
|
||||
}
|
||||
|
||||
#[derive(Copy, Clone, Eq, PartialEq)]
|
||||
pub enum SeekBias {
|
||||
Left,
|
||||
Right,
|
||||
}
|
||||
|
||||
#[derive(Debug, Clone)]
|
||||
pub struct SumTree<T: Item>(Arc<Node<T>>);
|
||||
|
||||
impl<T: Item> SumTree<T> {
|
||||
pub fn new() -> Self {
|
||||
SumTree(Arc::new(Node::Leaf {
|
||||
summary: T::Summary::default(),
|
||||
items: ArrayVec::new(),
|
||||
item_summaries: ArrayVec::new(),
|
||||
}))
|
||||
}
|
||||
|
||||
pub fn from_item(item: T) -> Self {
|
||||
let mut tree = Self::new();
|
||||
tree.push(item);
|
||||
tree
|
||||
}
|
||||
|
||||
pub fn items(&self) -> Vec<T> {
|
||||
let mut cursor = self.cursor::<(), ()>();
|
||||
cursor.descend_to_first_item(self, |_| true);
|
||||
cursor.cloned().collect()
|
||||
}
|
||||
|
||||
pub fn cursor<'a, S, U>(&'a self) -> Cursor<T, S, U>
|
||||
where
|
||||
S: Dimension<'a, T::Summary>,
|
||||
U: Dimension<'a, T::Summary>,
|
||||
{
|
||||
Cursor::new(self)
|
||||
}
|
||||
|
||||
pub fn filter<'a, F, U>(&'a self, filter_node: F) -> FilterCursor<F, T, U>
|
||||
where
|
||||
F: Fn(&T::Summary) -> bool,
|
||||
U: Dimension<'a, T::Summary>,
|
||||
{
|
||||
FilterCursor::new(self, filter_node)
|
||||
}
|
||||
|
||||
#[allow(dead_code)]
|
||||
pub fn first(&self) -> Option<&T> {
|
||||
self.leftmost_leaf().0.items().first()
|
||||
}
|
||||
|
||||
pub fn last(&self) -> Option<&T> {
|
||||
self.rightmost_leaf().0.items().last()
|
||||
}
|
||||
|
||||
pub fn extent<'a, D: Dimension<'a, T::Summary>>(&'a self) -> D {
|
||||
let mut extent = D::default();
|
||||
match self.0.as_ref() {
|
||||
Node::Internal { summary, .. } | Node::Leaf { summary, .. } => {
|
||||
extent.add_summary(summary)
|
||||
}
|
||||
}
|
||||
extent
|
||||
}
|
||||
|
||||
pub fn summary(&self) -> T::Summary {
|
||||
match self.0.as_ref() {
|
||||
Node::Internal { summary, .. } => summary.clone(),
|
||||
Node::Leaf { summary, .. } => summary.clone(),
|
||||
}
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
pub fn is_empty(&self) -> bool {
|
||||
match self.0.as_ref() {
|
||||
Node::Internal { .. } => false,
|
||||
Node::Leaf { items, .. } => items.is_empty(),
|
||||
}
|
||||
}
|
||||
|
||||
pub fn extend<I>(&mut self, iter: I)
|
||||
where
|
||||
I: IntoIterator<Item = T>,
|
||||
{
|
||||
let mut leaf: Option<Node<T>> = None;
|
||||
|
||||
for item in iter {
|
||||
if leaf.is_some() && leaf.as_ref().unwrap().items().len() == 2 * TREE_BASE {
|
||||
self.push_tree(SumTree(Arc::new(leaf.take().unwrap())));
|
||||
}
|
||||
|
||||
if leaf.is_none() {
|
||||
leaf = Some(Node::Leaf::<T> {
|
||||
summary: T::Summary::default(),
|
||||
items: ArrayVec::new(),
|
||||
item_summaries: ArrayVec::new(),
|
||||
});
|
||||
}
|
||||
|
||||
if let Some(Node::Leaf {
|
||||
summary,
|
||||
items,
|
||||
item_summaries,
|
||||
}) = leaf.as_mut()
|
||||
{
|
||||
let item_summary = item.summary();
|
||||
*summary += &item_summary;
|
||||
items.push(item);
|
||||
item_summaries.push(item_summary);
|
||||
} else {
|
||||
unreachable!()
|
||||
}
|
||||
}
|
||||
|
||||
if leaf.is_some() {
|
||||
self.push_tree(SumTree(Arc::new(leaf.take().unwrap())));
|
||||
}
|
||||
}
|
||||
|
||||
pub fn push(&mut self, item: T) {
|
||||
let summary = item.summary();
|
||||
self.push_tree(SumTree::from_child_trees(vec![SumTree(Arc::new(
|
||||
Node::Leaf {
|
||||
summary: summary.clone(),
|
||||
items: ArrayVec::from_iter(Some(item)),
|
||||
item_summaries: ArrayVec::from_iter(Some(summary)),
|
||||
},
|
||||
))]))
|
||||
}
|
||||
|
||||
pub fn push_tree(&mut self, other: Self) {
|
||||
let other_node = other.0.clone();
|
||||
if !other_node.is_leaf() || other_node.items().len() > 0 {
|
||||
if self.0.height() < other_node.height() {
|
||||
for tree in other_node.child_trees() {
|
||||
self.push_tree(tree.clone());
|
||||
}
|
||||
} else if let Some(split_tree) = self.push_tree_recursive(other) {
|
||||
*self = Self::from_child_trees(vec![self.clone(), split_tree]);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn push_tree_recursive(&mut self, other: SumTree<T>) -> Option<SumTree<T>> {
|
||||
match Arc::make_mut(&mut self.0) {
|
||||
Node::Internal {
|
||||
height,
|
||||
summary,
|
||||
child_summaries,
|
||||
child_trees,
|
||||
..
|
||||
} => {
|
||||
let other_node = other.0.clone();
|
||||
*summary += other_node.summary();
|
||||
|
||||
let height_delta = *height - other_node.height();
|
||||
let mut summaries_to_append = ArrayVec::<[T::Summary; 2 * TREE_BASE]>::new();
|
||||
let mut trees_to_append = ArrayVec::<[SumTree<T>; 2 * TREE_BASE]>::new();
|
||||
if height_delta == 0 {
|
||||
summaries_to_append.extend(other_node.child_summaries().iter().cloned());
|
||||
trees_to_append.extend(other_node.child_trees().iter().cloned());
|
||||
} else if height_delta == 1 && !other_node.is_underflowing() {
|
||||
summaries_to_append.push(other_node.summary().clone());
|
||||
trees_to_append.push(other)
|
||||
} else {
|
||||
let tree_to_append = child_trees.last_mut().unwrap().push_tree_recursive(other);
|
||||
*child_summaries.last_mut().unwrap() =
|
||||
child_trees.last().unwrap().0.summary().clone();
|
||||
|
||||
if let Some(split_tree) = tree_to_append {
|
||||
summaries_to_append.push(split_tree.0.summary().clone());
|
||||
trees_to_append.push(split_tree);
|
||||
}
|
||||
}
|
||||
|
||||
let child_count = child_trees.len() + trees_to_append.len();
|
||||
if child_count > 2 * TREE_BASE {
|
||||
let left_summaries: ArrayVec<_>;
|
||||
let right_summaries: ArrayVec<_>;
|
||||
let left_trees;
|
||||
let right_trees;
|
||||
|
||||
let midpoint = (child_count + child_count % 2) / 2;
|
||||
{
|
||||
let mut all_summaries = child_summaries
|
||||
.iter()
|
||||
.chain(summaries_to_append.iter())
|
||||
.cloned();
|
||||
left_summaries = all_summaries.by_ref().take(midpoint).collect();
|
||||
right_summaries = all_summaries.collect();
|
||||
let mut all_trees =
|
||||
child_trees.iter().chain(trees_to_append.iter()).cloned();
|
||||
left_trees = all_trees.by_ref().take(midpoint).collect();
|
||||
right_trees = all_trees.collect();
|
||||
}
|
||||
*summary = sum(left_summaries.iter());
|
||||
*child_summaries = left_summaries;
|
||||
*child_trees = left_trees;
|
||||
|
||||
Some(SumTree(Arc::new(Node::Internal {
|
||||
height: *height,
|
||||
summary: sum(right_summaries.iter()),
|
||||
child_summaries: right_summaries,
|
||||
child_trees: right_trees,
|
||||
})))
|
||||
} else {
|
||||
child_summaries.extend(summaries_to_append);
|
||||
child_trees.extend(trees_to_append);
|
||||
None
|
||||
}
|
||||
}
|
||||
Node::Leaf {
|
||||
summary,
|
||||
items,
|
||||
item_summaries,
|
||||
} => {
|
||||
let other_node = other.0;
|
||||
|
||||
let child_count = items.len() + other_node.items().len();
|
||||
if child_count > 2 * TREE_BASE {
|
||||
let left_items;
|
||||
let right_items;
|
||||
let left_summaries;
|
||||
let right_summaries: ArrayVec<[T::Summary; 2 * TREE_BASE]>;
|
||||
|
||||
let midpoint = (child_count + child_count % 2) / 2;
|
||||
{
|
||||
let mut all_items = items.iter().chain(other_node.items().iter()).cloned();
|
||||
left_items = all_items.by_ref().take(midpoint).collect();
|
||||
right_items = all_items.collect();
|
||||
|
||||
let mut all_summaries = item_summaries
|
||||
.iter()
|
||||
.chain(other_node.child_summaries())
|
||||
.cloned();
|
||||
left_summaries = all_summaries.by_ref().take(midpoint).collect();
|
||||
right_summaries = all_summaries.collect();
|
||||
}
|
||||
*items = left_items;
|
||||
*item_summaries = left_summaries;
|
||||
*summary = sum(item_summaries.iter());
|
||||
Some(SumTree(Arc::new(Node::Leaf {
|
||||
items: right_items,
|
||||
summary: sum(right_summaries.iter()),
|
||||
item_summaries: right_summaries,
|
||||
})))
|
||||
} else {
|
||||
*summary += other_node.summary();
|
||||
items.extend(other_node.items().iter().cloned());
|
||||
item_summaries.extend(other_node.child_summaries().iter().cloned());
|
||||
None
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn from_child_trees(child_trees: Vec<SumTree<T>>) -> Self {
|
||||
let height = child_trees[0].0.height() + 1;
|
||||
let mut child_summaries = ArrayVec::new();
|
||||
for child in &child_trees {
|
||||
child_summaries.push(child.0.summary().clone());
|
||||
}
|
||||
let summary = sum(child_summaries.iter());
|
||||
SumTree(Arc::new(Node::Internal {
|
||||
height,
|
||||
summary,
|
||||
child_summaries,
|
||||
child_trees: ArrayVec::from_iter(child_trees),
|
||||
}))
|
||||
}
|
||||
|
||||
fn leftmost_leaf(&self) -> &Self {
|
||||
match *self.0 {
|
||||
Node::Leaf { .. } => self,
|
||||
Node::Internal {
|
||||
ref child_trees, ..
|
||||
} => child_trees.first().unwrap().leftmost_leaf(),
|
||||
}
|
||||
}
|
||||
|
||||
fn rightmost_leaf(&self) -> &Self {
|
||||
match *self.0 {
|
||||
Node::Leaf { .. } => self,
|
||||
Node::Internal {
|
||||
ref child_trees, ..
|
||||
} => child_trees.last().unwrap().rightmost_leaf(),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
impl<T: KeyedItem> SumTree<T> {
|
||||
pub fn insert(&mut self, item: T) {
|
||||
*self = {
|
||||
let mut cursor = self.cursor::<T::Key, ()>();
|
||||
let mut new_tree = cursor.slice(&item.key(), SeekBias::Left);
|
||||
new_tree.push(item);
|
||||
new_tree.push_tree(cursor.suffix());
|
||||
new_tree
|
||||
};
|
||||
}
|
||||
|
||||
pub fn edit(&mut self, edits: &mut [Edit<T>]) {
|
||||
if edits.is_empty() {
|
||||
return;
|
||||
}
|
||||
|
||||
edits.sort_unstable_by_key(|item| item.key());
|
||||
|
||||
*self = {
|
||||
let mut cursor = self.cursor::<T::Key, ()>();
|
||||
let mut new_tree = SumTree::new();
|
||||
let mut buffered_items = Vec::new();
|
||||
|
||||
cursor.seek(&T::Key::default(), SeekBias::Left);
|
||||
for edit in edits {
|
||||
let new_key = edit.key();
|
||||
let mut old_item = cursor.item();
|
||||
|
||||
if old_item
|
||||
.as_ref()
|
||||
.map_or(false, |old_item| old_item.key() < new_key)
|
||||
{
|
||||
new_tree.extend(buffered_items.drain(..));
|
||||
let slice = cursor.slice(&new_key, SeekBias::Left);
|
||||
new_tree.push_tree(slice);
|
||||
old_item = cursor.item();
|
||||
}
|
||||
if old_item.map_or(false, |old_item| old_item.key() == new_key) {
|
||||
cursor.next();
|
||||
}
|
||||
match edit {
|
||||
Edit::Insert(item) => {
|
||||
buffered_items.push(item.clone());
|
||||
}
|
||||
Edit::Remove(_) => {}
|
||||
}
|
||||
}
|
||||
|
||||
new_tree.extend(buffered_items);
|
||||
new_tree.push_tree(cursor.suffix());
|
||||
new_tree
|
||||
};
|
||||
}
|
||||
}
|
||||
|
||||
#[derive(Clone, Debug)]
|
||||
pub enum Node<T: Item> {
|
||||
Internal {
|
||||
height: u8,
|
||||
summary: T::Summary,
|
||||
child_summaries: ArrayVec<[T::Summary; 2 * TREE_BASE]>,
|
||||
child_trees: ArrayVec<[SumTree<T>; 2 * TREE_BASE]>,
|
||||
},
|
||||
Leaf {
|
||||
summary: T::Summary,
|
||||
items: ArrayVec<[T; 2 * TREE_BASE]>,
|
||||
item_summaries: ArrayVec<[T::Summary; 2 * TREE_BASE]>,
|
||||
},
|
||||
}
|
||||
|
||||
impl<T: Item> Node<T> {
|
||||
fn is_leaf(&self) -> bool {
|
||||
match self {
|
||||
Node::Leaf { .. } => true,
|
||||
_ => false,
|
||||
}
|
||||
}
|
||||
|
||||
fn height(&self) -> u8 {
|
||||
match self {
|
||||
Node::Internal { height, .. } => *height,
|
||||
Node::Leaf { .. } => 0,
|
||||
}
|
||||
}
|
||||
|
||||
fn summary(&self) -> &T::Summary {
|
||||
match self {
|
||||
Node::Internal { summary, .. } => summary,
|
||||
Node::Leaf { summary, .. } => summary,
|
||||
}
|
||||
}
|
||||
|
||||
fn child_summaries(&self) -> &[T::Summary] {
|
||||
match self {
|
||||
Node::Internal {
|
||||
child_summaries, ..
|
||||
} => child_summaries.as_slice(),
|
||||
Node::Leaf { item_summaries, .. } => item_summaries.as_slice(),
|
||||
}
|
||||
}
|
||||
|
||||
fn child_trees(&self) -> &ArrayVec<[SumTree<T>; 2 * TREE_BASE]> {
|
||||
match self {
|
||||
Node::Internal { child_trees, .. } => child_trees,
|
||||
Node::Leaf { .. } => panic!("Leaf nodes have no child trees"),
|
||||
}
|
||||
}
|
||||
|
||||
fn items(&self) -> &ArrayVec<[T; 2 * TREE_BASE]> {
|
||||
match self {
|
||||
Node::Leaf { items, .. } => items,
|
||||
Node::Internal { .. } => panic!("Internal nodes have no items"),
|
||||
}
|
||||
}
|
||||
|
||||
fn is_underflowing(&self) -> bool {
|
||||
match self {
|
||||
Node::Internal { child_trees, .. } => child_trees.len() < TREE_BASE,
|
||||
Node::Leaf { items, .. } => items.len() < TREE_BASE,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
#[derive(Debug)]
|
||||
pub enum Edit<T: KeyedItem> {
|
||||
Insert(T),
|
||||
Remove(T),
|
||||
}
|
||||
|
||||
impl<T: KeyedItem> Edit<T> {
|
||||
fn key(&self) -> T::Key {
|
||||
match self {
|
||||
Edit::Insert(item) | Edit::Remove(item) => item.key(),
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn sum<'a, T, I>(iter: I) -> T
|
||||
where
|
||||
T: 'a + Default + AddAssign<&'a T>,
|
||||
I: Iterator<Item = &'a T>,
|
||||
{
|
||||
let mut sum = T::default();
|
||||
for value in iter {
|
||||
sum += value;
|
||||
}
|
||||
sum
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use std::ops::Add;
|
||||
|
||||
#[test]
|
||||
fn test_extend_and_push_tree() {
|
||||
let mut tree1 = SumTree::new();
|
||||
tree1.extend(0..20);
|
||||
|
||||
let mut tree2 = SumTree::new();
|
||||
tree2.extend(50..100);
|
||||
|
||||
tree1.push_tree(tree2);
|
||||
assert_eq!(tree1.items(), (0..20).chain(50..100).collect::<Vec<u8>>());
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_random() {
|
||||
for seed in 0..100 {
|
||||
use rand::{distributions, prelude::*};
|
||||
|
||||
let rng = &mut StdRng::seed_from_u64(seed);
|
||||
|
||||
let mut tree = SumTree::<u8>::new();
|
||||
let count = rng.gen_range(0..10);
|
||||
tree.extend(rng.sample_iter(distributions::Standard).take(count));
|
||||
|
||||
for _ in 0..5 {
|
||||
let splice_end = rng.gen_range(0..tree.extent::<Count>().0 + 1);
|
||||
let splice_start = rng.gen_range(0..splice_end + 1);
|
||||
let count = rng.gen_range(0..3);
|
||||
let tree_end = tree.extent::<Count>();
|
||||
let new_items = rng
|
||||
.sample_iter(distributions::Standard)
|
||||
.take(count)
|
||||
.collect::<Vec<u8>>();
|
||||
|
||||
let mut reference_items = tree.items();
|
||||
reference_items.splice(splice_start..splice_end, new_items.clone());
|
||||
|
||||
tree = {
|
||||
let mut cursor = tree.cursor::<Count, ()>();
|
||||
let mut new_tree = cursor.slice(&Count(splice_start), SeekBias::Right);
|
||||
new_tree.extend(new_items);
|
||||
cursor.seek(&Count(splice_end), SeekBias::Right);
|
||||
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
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user