Struct TreeModel 

pub struct TreeModel<T: 'static> { /* private fields */ }

A concrete reactive tree that stores a hierarchy of T items in a flat arena.

TreeModel<T> is Clone — cloning produces a second handle to the same underlying data. All handles see the same hierarchy and receive the same TreeChange notifications from observe_changes. Nodes are identified by opaque NodeId handles that are stable and non-reusable across mutations (versioned SlotMap keys).

Implementations

impl<T: 'static> TreeModel<T>

pub fn new() -> Self

Create an empty tree model with no roots and no observers.

pub fn root_count(&self) -> usize

Number of root-level nodes.

pub fn root(&self, index: usize) -> NodeId

Get the NodeId of a root-level node by index.

Panics

Panics if index >= root_count().

pub fn child_count(&self, parent: NodeId) -> usize

Number of children of the given node.

pub fn child(&self, parent: NodeId, index: usize) -> NodeId

Get the NodeId of a child by parent and index.

Panics

Panics if the parent or index is invalid.

pub fn parent(&self, node: NodeId) -> Option<NodeId>

Get the parent of a node, or None if it is a root.

pub fn depth(&self, node: NodeId) -> usize

Compute the depth of a node (0 for roots).

pub fn has_children(&self, node: NodeId) -> bool

Whether the given node has any children.

pub fn children(&self, node: NodeId) -> Vec<NodeId>

Get the children of a node as a vector of NodeId.

pub fn with_item<R>(&self, node: NodeId, f: impl FnOnce(&T) -> R) -> Option<R>

Access a node’s data via a callback. Returns None if the node doesn’t exist.

pub fn find_by(&self, predicate: impl Fn(&T) -> bool) -> Option<NodeId>

Find the first node matching a predicate (depth-first from roots).

pub fn insert_root(&self, index: usize, item: T) -> NodeId

Insert a new root-level node at the given index.

Panics

Panics if index > root_count().

pub fn insert_child(&self, parent: NodeId, index: usize, item: T) -> NodeId

Insert a new child node under the given parent at the given index.

Panics

Panics if the parent is invalid or index > child_count(parent).

pub fn remove(&self, node: NodeId)

Remove a node and its entire subtree.

Panics

Panics if the node is invalid.

pub fn move_node(&self, node: NodeId, new_parent: NodeId, new_index: usize)

Move a node (and its subtree) to a new parent at the given index.

Panics

Panics if any of the nodes are invalid, or if the target is a descendant of the source (would create a cycle).

pub fn move_to_root(&self, node: NodeId, new_index: usize)

Move a node to the root level at the given index.

pub fn update(&self, node: NodeId, item: T)

Update a node’s data in place.

Panics

Panics if the node is invalid.

pub fn observe_changes( &self, f: impl Fn(&TreeChange) + 'static, ) -> ObserverHandle

Register an observer for tree change notifications. Returns an ObserverHandle — dropping it removes the callback.

impl<T: Debug + 'static> TreeModel<T>

pub fn debug_named(self, _name: impl Into<String>) -> Self

Register this tree with the debug inspector under name. In release builds (!cfg(debug_assertions)) this is a no-op pass-through so call sites stay free of #[cfg] lines.

Idempotent on repeated calls — the latest registration wins. The registration drops automatically when the last TreeModel handle is freed (the adapter the registry holds is Weak).

Trait Implementations

impl<T: 'static> Clone for TreeModel<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + 'static> Debug for TreeModel<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: 'static> Default for TreeModel<T>

fn default() -> Self

Returns the “default value” for a type.