TreeSlice

TreeSlice — per-view flattened projection of a TreeModel.

TreeSlice<T> wraps a TreeModel<T> and maintains an independent expand/collapse set so two TreeView widgets sharing the same model have independent visible rows — dual-pane file managers, overview/detail splits, and search results panels are each one TreeSlice::new(model.clone()). The slice re-flattens automatically whenever the underlying model emits a TreeChange, and bumps a version_signal Signal<u64> that views bind at BindingLevel::Rebuild.

A lightweight TreeSliceHandle (created via TreeSlice::handle) shares all Rc-based internals and is usable in closures without keeping the tree-change observer alive.

TreeSlice implements TreeDataSource and is the built-in source for TreeView / TreeTableView.

Example

#![allow(unused)]
fn main() {
use teksilo_data::{TreeModel, TreeSlice};
let tree = TreeModel::new();
let root = tree.insert_root(0, "root");
let child = tree.insert_child(root, 0, "child");

let slice1 = TreeSlice::new(tree.clone());
let slice2 = TreeSlice::new(tree.clone());

slice1.expand(root);
assert_eq!(slice1.visible_count(), 2); // root + child visible
assert_eq!(slice2.visible_count(), 1); // still collapsed in slice2

// Inserting into the model notifies both slices.
tree.insert_child(root, 1, "child2");
assert_eq!(slice1.visible_count(), 3); // child2 also visible in the expanded slice
}

Builder methods at a glance

visible_count, with_entry, visible_node_id, entry_at, depth_at, flat_index_of, is_expanded, expand, collapse, toggle, expand_all, collapse_all, expanded_nodes, set_expanded_nodes, version_signal, first_changed_index, tree, handle

API reference

📖 Full rustdoc API for this module

pub struct TreeSlice

Per-view flattened projection of a TreeModel<T>.

Owns an independent expand/collapse set and re-flattens automatically on every TreeChange from the underlying model. Two slices over the same model have completely independent expand state. See the module documentation for the full picture.

#![allow(unused)]
fn main() {
pub struct TreeSlice<T: 'static> { /* fields */ }
}

Methods

pub fn new(tree: TreeModel<T>) -> Self

Create a new TreeSlice for the given TreeModel. All nodes start collapsed (only roots are visible).

pub fn visible_count(&self) -> usize

Number of currently visible (flattened) rows.

pub fn with_entry<R>( &self, flat_index: usize, f: impl FnOnce(&T, &FlatEntry) -> R, ) -> Option<R>

Access a flat entry by index via callback. The callback receives (&T, &FlatEntry).

pub fn visible_node_id(&self, flat_index: usize) -> Option<NodeId>

Get the NodeId at the given flat index.

pub fn entry_at(&self, flat_index: usize) -> Option<FlatEntry>

Get the FlatEntry at the given flat index (cloned).

pub fn depth_at(&self, flat_index: usize) -> usize

Get the depth at the given flat index.

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

Find the flat index for a given NodeId, or None if not visible. O(1) — backed by a position map rebuilt on every reflatten.

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

Whether the given node is expanded.

pub fn expand(&self, node: NodeId)

Expand a node (make its children visible).

pub fn collapse(&self, node: NodeId)

Collapse a node (hide its children).

pub fn toggle(&self, node: NodeId)

Toggle expand/collapse state of a node.

pub fn expand_all(&self)

Expand all nodes in the tree.

pub fn collapse_all(&self)

Collapse all nodes in the tree.

pub fn expanded_nodes(&self) -> Vec<NodeId>

Get all expanded node IDs (for persistence).

pub fn set_expanded_nodes(&self, nodes: &[NodeId])

Restore expanded state (for persistence).

pub fn version_signal(&self) -> Signal<u64>

Get the version signal for binding to BindingLevel::Rebuild.

pub fn first_changed_index(&self) -> Option<usize>

First flat index whose content may differ from before the latest reflatten — the rows 0..index are the same nodes, at the same depths, with the same expand state as before, so any per-row derived state (e.g. a measured row height) remains valid for them. Equal to visible_count() when the visible list is unchanged.

None means unknown (no reflatten observed yet) — treat as a full change. The value describes the latest reflatten only; read it synchronously from a version_signal() observer (observers fire inline on every bump, so per-change reads cannot miss a value).

pub fn tree(&self) -> &TreeModel<T>

Access the underlying TreeModel.

pub fn handle(&self) -> TreeSliceHandle<T>

Create a lightweight handle for use in closures. Shares all Rc-based internals but does not keep the observer alive.

pub struct TreeSliceHandle

Lightweight handle to a TreeSlice's shared state, usable in closures.

Created via TreeSlice::handle. Shares all Rc-based internals with its parent TreeSlice but does not keep the tree-change observer alive — the TreeSlice that owns the observer must outlive all handles that rely on automatic re-flattening on model changes.

#![allow(unused)]
fn main() {
pub struct TreeSliceHandle<T: 'static> { /* fields */ }
}

Methods

pub fn visible_count(&self) -> usize

Number of currently-visible (flattened) rows.

pub fn entry_at(&self, flat_index: usize) -> Option<FlatEntry>

Get the FlatEntry at flat_index (cloned), or None if out of bounds.

pub fn visible_node_id(&self, flat_index: usize) -> Option<NodeId>

Get the NodeId at flat_index, or None if out of bounds.

pub fn expand(&self, node: NodeId)

Expand node (make its children visible) and bump the version signal. No-op if already expanded.

pub fn collapse(&self, node: NodeId)

Collapse node (hide its children) and bump the version signal. No-op if already collapsed.

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

Returns true if node is currently expanded.

pub fn toggle_expand(&self, node: NodeId)

Toggle node's expand/collapse state and bump the version signal.

pub fn tree(&self) -> &TreeModel<T>

Access the underlying TreeModel.

pub fn expand_all(&self)

Expand every node with children — see TreeSlice::expand_all. Useful after a model rebuild reassigns NodeIds (the old expand set no longer matches), to keep the view fully expanded.

pub fn first_changed_index(&self) -> Option<usize>

See TreeSlice::first_changed_index.