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use std::ops::ControlFlow;
use super::{AsNodePath, InsertTransaction, Nodes, RemovedValues, TreeValues, ValueId};
#[derive(Debug)]
pub struct TreeView<'tree, T> {
pub offset: &'tree [u16],
pub values: &'tree mut TreeValues<T>,
pub layout: &'tree mut Nodes,
pub removed_values: &'tree mut RemovedValues,
}
impl<'tree, T> TreeView<'tree, T> {
pub fn new(
offset: &'tree [u16],
layout: &'tree mut Nodes,
values: &'tree mut TreeValues<T>,
removed_values: &'tree mut RemovedValues,
) -> Self {
Self {
offset,
values,
layout,
removed_values,
}
}
pub fn view(&mut self) -> TreeView<'_, T> {
TreeView::new(self.offset, self.layout, self.values, self.removed_values)
}
/// Get a mutable reference by value id
pub fn get_mut(&mut self, value_id: ValueId) -> Option<&mut T> {
self.values.get_mut(value_id).map(|(_, value)| value)
}
/// Get a reference by value id
pub fn get(&self, value_id: ValueId) -> Option<&T> {
self.values.get(value_id).map(|(_, value)| value)
}
pub fn contains(&self, key: ValueId) -> bool {
self.values.get(key).is_some()
}
/// The number of children (not counting childrens children)
pub fn layout_len(&self) -> usize {
self.layout.len()
}
pub fn for_each<F, U>(&mut self, mut f: F) -> Option<U>
where
F: FnMut(&[u16], &mut T, TreeView<'_, T>) -> ControlFlow<U>,
{
for index in 0..self.layout.len() {
let node = &mut self.layout.inner[index];
match self.values.with_mut(node.value, |(offset, value), values| {
let tree_view = TreeView::new(offset, &mut node.children, values, self.removed_values);
f(offset, value, tree_view)
}) {
ControlFlow::Continue(_) => continue,
ControlFlow::Break(value) => return Some(value),
}
}
None
}
// The path reference for a value in the tree.
// Unlike a `ValueId` which will never change for a given value,
// the `NodePath` can change if the node is moved to another location within the tree.
//
// # Panics
//
// Panics if the value id is no long present in the tree.
fn path_ref(&self, id: impl Into<ValueId>) -> &[u16] {
let id = id.into();
let (path, _) = self
.values
.get(id)
.expect("an id should always be associated with a path");
path
}
/// The path to a value in the tree.
/// Unlike a `ValueId` which will never change for a given value,
/// the `NodePath` can change if the node is moved to another location within the tree.
///
/// # Panics
///
/// Panics if the value id is no long present in the tree.
pub fn path(&self, id: impl Into<ValueId>) -> Box<[u16]> {
self.path_ref(id).into()
}
// Find the value id by the path
fn id(&self, path: &[u16]) -> Option<ValueId> {
self.layout.with(path, |nodes| nodes.value())
}
/// Get a reference to the value and the value id
/// This has an additional cost since the value id has to
/// be found first.
pub fn get_node_and_value(&self, path: &[u16]) -> Option<(ValueId, &T)> {
let id = self.id(path)?;
self.values.get(id).map(|(_, val)| (id, val))
}
/// Being an insert transaction.
/// The transaction has to be committed before the value is written to
/// the tree.
/// ```
/// # use anathema_store::tree::*;
/// let mut tree = Tree::empty();
/// let mut tree = tree.view();
/// let transaction = tree.insert(&[]);
/// let value_id = transaction.commit_child(1usize).unwrap();
/// let one = tree.get_mut(value_id).unwrap();
/// assert_eq!(*one, 1);
/// ```
pub fn insert<'a>(&'a mut self, parent: &'a [u16]) -> InsertTransaction<'a, 'tree, T> {
InsertTransaction::new(self, parent)
}
/// Remove all the nodes in this view
pub fn truncate_children<F>(&mut self, f: &mut F)
where
F: FnMut(T),
{
self.layout.clear(self.values, self.removed_values, f);
}
/// Remove a `Node` and value from the tree.
/// This will also remove all the children and associated values.
pub fn relative_remove<F>(&mut self, path: &[u16], f: &mut F)
where
F: FnMut(T),
{
if self.layout.is_empty() {
return;
}
// This will not return the value that was removed, as it will also
// remove all the children under that node.
let (path, index) = path.split_parent().expect("a value will always exist within the tree");
let node = self.layout.with_mut(path, |nodes| {
let node = nodes.remove(index);
nodes.inner[index..].iter_mut().for_each(|node| {
// Update the subsequent siblings by bumping their index by one
let (path, _) = self.values.get_mut(node.value).expect("every node has a value");
path[path.len() - 1] -= 1;
// Clone the path to drop the borrow of the tree
let path = path.clone();
// Update the root of all the children of the preceding siblings
node.reparent(&path, self.values);
});
node
});
if let Some(mut node) = node {
let value_key = node.value();
_ = self
.values
.remove(value_key)
.expect("a node is always associated with a value");
self.removed_values.insert(value_key);
node.children.clear(self.values, self.removed_values, f);
}
}
/// Perform a given operation (`F`) on a mutable reference to a value in the tree
/// while still having mutable access to the rest of the tree.
///
/// # Panics
///
/// This will panic if the value is already checked out
pub fn with_value_mut<F, V>(&mut self, value_id: ValueId, f: F) -> Option<V>
where
F: FnOnce(&[u16], &mut T, TreeView<'_, T>) -> V,
{
let mut ticket = self.values.checkout(value_id);
let (path, value) = &mut *ticket;
let node = self.layout.get_by_path_mut(&path[self.offset.len()..])?;
let view = TreeView {
offset: path,
values: self.values,
layout: node.children_mut(),
removed_values: self.removed_values,
};
let value = f(path, value, view);
self.values.restore(ticket);
Some(value)
}
pub fn nodes_and_values(&self) -> (&[super::Node], &TreeValues<T>) {
(self.layout, self.values)
}
#[cfg(test)]
fn get_ref_by_path(&self, path: &[u16]) -> Option<&T> {
let relative = &path[self.offset.len()..];
let id = self.id(relative)?;
self.values.get(id).map(|(_, val)| val)
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::tree::{Tree, root_node};
#[test]
fn insert_and_commit() {
// let mut tree = Tree::<u32>::empty();
// let mut tree = tree.view();
// let transaction = tree.insert(root_node());
// let node_id = transaction.node_id();
// let value = 123;
// transaction.commit_child(value);
// assert_eq!(*tree.get_ref_by_id(node_id).unwrap(), 123);
}
#[test]
fn insert_without_commit() {
// let mut tree = Tree::<()>::empty();
// let mut tree = tree.view();
// let transaction = tree.insert(root_node());
// let node_id = transaction.node_id();
// assert!(tree.get_ref_by_id(node_id).is_none());
}
#[test]
fn get_by_path() {
let mut tree = Tree::empty();
let mut tree = tree.view();
let node_id = tree.insert(root_node()).commit_child(1).unwrap();
let path = tree.path(node_id);
tree.insert(&path).commit_child(2);
let one = tree.get_ref_by_path(&[0]).unwrap();
let two = tree.get_ref_by_path(&[0, 0]).unwrap();
assert_eq!(*one, 1);
assert_eq!(*two, 2);
}
#[test]
fn with_node_id_reading_checkedout_value() {
let mut tree = Tree::empty();
let mut tree = tree.view();
let key = tree.insert(root_node()).commit_child(0).unwrap();
tree.insert(root_node()).commit_child(1);
tree.with_value_mut(key, |_path, _value, mut tree| {
// The value is already checked out
assert!(tree.get_mut(key).is_none());
});
}
#[test]
fn remove_children() {
let mut tree = Tree::<u32>::empty();
let mut tree = tree.view();
tree.insert(root_node()).commit_child(1);
let path = &[0, 0];
tree.insert(path).commit_at(2);
assert!(tree.get_ref_by_path(path).is_some());
tree.relative_remove(path, &mut |_| {});
assert!(tree.get_ref_by_path(path).is_none());
}
// This is where we start:
// Insert At has to be a possibility.
// Scenario:
// * Insert at 0
// * Insert at len
// * Insert in the middle
#[test]
fn insert_at_path() {
let mut tree = Tree::empty();
let mut tree = tree.view();
// Setup: add two entries
// First entry
let key = tree.insert(root_node()).commit_child(0).unwrap();
let _sibling_path = tree.path_ref(key);
// Second entry (with two children)
let key_1 = tree.insert(root_node()).commit_child(1).unwrap();
let parent: Box<_> = tree.path_ref(key_1).into();
// Insert two values under the second entry
let key_1_0 = tree.insert(&parent).commit_child(5).unwrap();
let key_1_1 = tree.insert(&parent).commit_child(6).unwrap();
// Assert 1.
// First assertion that the paths are all rooted in [1]
assert_eq!(tree.path_ref(key_1), &[1]);
assert_eq!(tree.path_ref(key_1_0), &[1, 0]);
assert_eq!(tree.path_ref(key_1_1), &[1, 1]);
// Insert a node as the new first node ([0]), which should update
// the path for all the other entries in the tree
let insert_at = &[0];
tree.insert(insert_at).commit_at(123).unwrap();
// Assert 2
// Second assertion that the paths are all rooted in [2]
assert_eq!(tree.path_ref(key_1), &[2]);
assert_eq!(tree.path_ref(key_1_0), &[2, 0]);
assert_eq!(tree.path_ref(key_1_1), &[2, 1]);
// Insert a node as the new last node ([0]), which should update
// the path for all the other entries in the tree
let insert_at = [3];
let key_3 = tree.insert(&insert_at).commit_at(999).unwrap();
// Assert 3
assert_eq!(tree.path_ref(key_3), &[3]);
}
#[test]
fn modify_tree() {
let mut tree = Tree::<usize>::empty();
tree.view().insert(root_node()).commit_child(123);
let path = &[0, 0];
tree.view().insert(path).commit_at(1);
let mut tree = tree.view();
tree.for_each(|_path, outer_value, mut children| {
children.for_each(|_path, inner_value, mut children| {
let parent = &[0, 0];
children.insert(parent).commit_child(999);
let path = &[0, 0, 0];
let value = children.get_ref_by_path(path).unwrap();
assert_eq!(*value, 999);
assert_eq!(*outer_value, 123);
assert_eq!(*inner_value, 1);
ControlFlow::Continue::<(), _>(())
});
ControlFlow::Break(())
});
}
}