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//! Node.
#[cfg(not(feature = "std"))]
use core::fmt;
#[cfg(feature = "deser")]
use serde::{Deserialize, Serialize};
#[cfg(feature = "std")]
use std::fmt;
use crate::{id::NodeStamp, NodeId};
#[derive(PartialEq, Eq, Clone, Debug)]
#[cfg_attr(feature = "deser", derive(Deserialize, Serialize))]
pub(crate) enum NodeData<T> {
/// The actual data store
Data(T),
/// The next free node position.
NextFree(Option<usize>),
}
#[derive(PartialEq, Eq, Clone, Debug)]
#[cfg_attr(feature = "deser", derive(Deserialize, Serialize))]
/// A node within a particular `Arena`.
pub struct Node<T> {
// Keep these private (with read-only accessors) so that we can keep them
// consistent. E.g. the parent of a node’s child is that node.
pub(crate) parent: Option<NodeId>,
pub(crate) previous_sibling: Option<NodeId>,
pub(crate) next_sibling: Option<NodeId>,
pub(crate) first_child: Option<NodeId>,
pub(crate) last_child: Option<NodeId>,
pub(crate) stamp: NodeStamp,
/// The actual data which will be stored within the tree.
pub(crate) data: NodeData<T>,
}
impl<T> Node<T> {
/// Returns a reference to the node data.
pub fn get(&self) -> &T {
if let NodeData::Data(ref data) = self.data {
data
} else {
unreachable!("Try to access a freed node")
}
}
/// Returns a mutable reference to the node data.
pub fn get_mut(&mut self) -> &mut T {
if let NodeData::Data(ref mut data) = self.data {
data
} else {
unreachable!("Try to access a freed node")
}
}
/// Creates a new `Node` with the default state and the given data.
pub(crate) fn new(data: T) -> Self {
Self {
parent: None,
previous_sibling: None,
next_sibling: None,
first_child: None,
last_child: None,
stamp: NodeStamp::default(),
data: NodeData::Data(data),
}
}
/// Convert a removed `Node` to normal with default state and given data.
pub(crate) fn reuse(&mut self, data: T) {
debug_assert!(matches!(self.data, NodeData::NextFree(_)));
debug_assert!(self.stamp.is_removed());
self.stamp.reuse();
self.parent = None;
self.previous_sibling = None;
self.next_sibling = None;
self.first_child = None;
self.last_child = None;
self.data = NodeData::Data(data);
}
/// Returns the ID of the parent node, unless this node is the root of the
/// tree.
///
/// # Examples
///
/// ```
/// # use indextree::Arena;
/// # let mut arena = Arena::new();
/// # let n1 = arena.new_node("1");
/// # let n1_1 = arena.new_node("1_1");
/// # let n1_2 = arena.new_node("1_2");
/// # n1.append(n1_2, &mut arena);
/// # let n1_3 = arena.new_node("1_3");
/// # n1.append(n1_3, &mut arena);
/// # n1.append(n1_1, &mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // |-- 1_2
/// // `-- 1_3
/// assert_eq!(arena[n1].parent(), None);
/// assert_eq!(arena[n1_1].parent(), Some(n1));
/// assert_eq!(arena[n1_2].parent(), Some(n1));
/// assert_eq!(arena[n1_3].parent(), Some(n1));
/// ```
pub fn parent(&self) -> Option<NodeId> {
self.parent
}
/// Returns the ID of the first child of this node, unless it has no child.
///
/// # Examples
///
/// ```
/// # use indextree::Arena;
/// # let mut arena = Arena::new();
/// # let n1 = arena.new_node("1");
/// # let n1_1 = arena.new_node("1_1");
/// # n1.append(n1_1, &mut arena);
/// # let n1_2 = arena.new_node("1_2");
/// # n1.append(n1_2, &mut arena);
/// # let n1_3 = arena.new_node("1_3");
/// # n1.append(n1_3, &mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // |-- 1_2
/// // `-- 1_3
/// assert_eq!(arena[n1].first_child(), Some(n1_1));
/// assert_eq!(arena[n1_1].first_child(), None);
/// assert_eq!(arena[n1_2].first_child(), None);
/// assert_eq!(arena[n1_3].first_child(), None);
/// ```
pub fn first_child(&self) -> Option<NodeId> {
self.first_child
}
/// Returns the ID of the last child of this node, unless it has no child.
///
/// # Examples
///
/// ```
/// # use indextree::Arena;
/// # let mut arena = Arena::new();
/// # let n1 = arena.new_node("1");
/// # let n1_1 = arena.new_node("1_1");
/// # n1.append(n1_1, &mut arena);
/// # let n1_2 = arena.new_node("1_2");
/// # n1.append(n1_2, &mut arena);
/// # let n1_3 = arena.new_node("1_3");
/// # n1.append(n1_3, &mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // |-- 1_2
/// // `-- 1_3
/// assert_eq!(arena[n1].last_child(), Some(n1_3));
/// assert_eq!(arena[n1_1].last_child(), None);
/// assert_eq!(arena[n1_2].last_child(), None);
/// assert_eq!(arena[n1_3].last_child(), None);
/// ```
pub fn last_child(&self) -> Option<NodeId> {
self.last_child
}
/// Returns the ID of the previous sibling of this node, unless it is a
/// first child.
///
/// # Examples
///
/// ```
/// # use indextree::Arena;
/// # let mut arena = Arena::new();
/// # let n1 = arena.new_node("1");
/// # let n1_1 = arena.new_node("1_1");
/// # n1.append(n1_1, &mut arena);
/// # let n1_2 = arena.new_node("1_2");
/// # n1.append(n1_2, &mut arena);
/// # let n1_3 = arena.new_node("1_3");
/// # n1.append(n1_3, &mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // |-- 1_2
/// // `-- 1_3
/// assert_eq!(arena[n1].previous_sibling(), None);
/// assert_eq!(arena[n1_1].previous_sibling(), None);
/// assert_eq!(arena[n1_2].previous_sibling(), Some(n1_1));
/// assert_eq!(arena[n1_3].previous_sibling(), Some(n1_2));
/// ```
///
/// Note that newly created nodes are independent toplevel nodes, and they
/// are not siblings by default.
///
/// ```
/// # use indextree::Arena;
/// let mut arena = Arena::new();
/// let n1 = arena.new_node("1");
/// let n2 = arena.new_node("2");
/// // arena
/// // |-- (implicit)
/// // | `-- 1
/// // `-- (implicit)
/// // `-- 2
/// assert_eq!(arena[n1].previous_sibling(), None);
/// assert_eq!(arena[n2].previous_sibling(), None);
///
/// n1.insert_after(n2, &mut arena);
/// // arena
/// // `-- (implicit)
/// // |-- 1
/// // `-- 2
/// assert_eq!(arena[n1].previous_sibling(), None);
/// assert_eq!(arena[n2].previous_sibling(), Some(n1));
/// ```
pub fn previous_sibling(&self) -> Option<NodeId> {
self.previous_sibling
}
/// Returns the ID of the next sibling of this node, unless it is a
/// last child.
///
/// # Examples
///
/// ```
/// # use indextree::Arena;
/// # let mut arena = Arena::new();
/// # let n1 = arena.new_node("1");
/// # let n1_1 = arena.new_node("1_1");
/// # n1.append(n1_1, &mut arena);
/// # let n1_2 = arena.new_node("1_2");
/// # n1.append(n1_2, &mut arena);
/// # let n1_3 = arena.new_node("1_3");
/// # n1.append(n1_3, &mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // |-- 1_2
/// // `-- 1_3
/// assert_eq!(arena[n1].next_sibling(), None);
/// assert_eq!(arena[n1_1].next_sibling(), Some(n1_2));
/// assert_eq!(arena[n1_2].next_sibling(), Some(n1_3));
/// assert_eq!(arena[n1_3].next_sibling(), None);
/// ```
///
/// Note that newly created nodes are independent toplevel nodes, and they
/// are not siblings by default.
///
/// ```
/// # use indextree::Arena;
/// let mut arena = Arena::new();
/// let n1 = arena.new_node("1");
/// let n2 = arena.new_node("2");
/// // arena
/// // |-- (implicit)
/// // | `-- 1
/// // `-- (implicit)
/// // `-- 2
/// assert_eq!(arena[n1].next_sibling(), None);
/// assert_eq!(arena[n2].next_sibling(), None);
///
/// n1.insert_after(n2, &mut arena);
/// // arena
/// // `-- (implicit)
/// // |-- 1
/// // `-- 2
/// assert_eq!(arena[n1].next_sibling(), Some(n2));
/// assert_eq!(arena[n2].next_sibling(), None);
/// ```
pub fn next_sibling(&self) -> Option<NodeId> {
self.next_sibling
}
/// Checks if the node is marked as removed.
///
/// # Examples
///
/// ```
/// # use indextree::Arena;
/// # let mut arena = Arena::new();
/// # let n1 = arena.new_node("1");
/// # let n1_1 = arena.new_node("1_1");
/// # n1.append(n1_1, &mut arena);
/// # let n1_2 = arena.new_node("1_2");
/// # n1.append(n1_2, &mut arena);
/// # let n1_3 = arena.new_node("1_3");
/// # n1.append(n1_3, &mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // |-- 1_2 *
/// // `-- 1_3
/// assert_eq!(arena[n1_1].next_sibling(), Some(n1_2));
/// assert_eq!(arena[n1_2].parent(), Some(n1));
/// assert!(!arena[n1_2].is_removed());
/// assert_eq!(arena[n1_3].previous_sibling(), Some(n1_2));
///
/// n1_2.remove(&mut arena);
/// // arena
/// // `-- 1
/// // |-- 1_1
/// // `-- 1_3
/// assert_eq!(arena[n1_1].next_sibling(), Some(n1_3));
/// assert_eq!(arena[n1_2].parent(), None);
/// assert!(arena[n1_2].is_removed());
/// assert_eq!(arena[n1_3].previous_sibling(), Some(n1_1));
/// ```
pub fn is_removed(&self) -> bool {
self.stamp.is_removed()
}
/// Checks if the node is detached.
pub(crate) fn is_detached(&self) -> bool {
self.parent.is_none() && self.previous_sibling.is_none() && self.next_sibling.is_none()
}
}
impl<T> fmt::Display for Node<T> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(parent) = self.parent {
write!(f, "parent: {}; ", parent)?;
} else {
write!(f, "no parent; ")?;
}
if let Some(previous_sibling) = self.previous_sibling {
write!(f, "previous sibling: {}; ", previous_sibling)?;
} else {
write!(f, "no previous sibling; ")?;
}
if let Some(next_sibling) = self.next_sibling {
write!(f, "next sibling: {}; ", next_sibling)?;
} else {
write!(f, "no next sibling; ")?;
}
if let Some(first_child) = self.first_child {
write!(f, "first child: {}; ", first_child)?;
} else {
write!(f, "no first child; ")?;
}
if let Some(last_child) = self.last_child {
write!(f, "last child: {}; ", last_child)?;
} else {
write!(f, "no last child; ")?;
}
Ok(())
}
}