TreeDataSource

TreeDataSource — read-and-command interface for hierarchical data behind a TreeView / TreeTableView.

TreeDataSource is to trees what ListDataSource is to flat lists: a projected, per-view, flattened read API plus the capability protocol for identity, DnD validation, and lazy loading. The built-in TreeSlice and SortFilterTreeModel implement it over an in-memory TreeModel; an external source of truth (e.g. a Qleany entity store) implements it directly with its own Key type and so never needs to mirror itself into a TreeModel.

When to use

Implement TreeDataSource directly when your data already lives outside an in-memory tree (a database, a virtual filesystem, a remote store) and you do not want to mirror it into a TreeModel. Use TreeSlice when you have a TreeModel<T> and want per-view expand state.

Example

use teksilo_data::{TreeDataSource, FlatEntry, NodeId};
use teksilo_data::dnd_types::{DragEligibility, DropQuery, DropResponse, DropCommit, RowState};
use teksilo_core::signal::Signal;

struct MySource { version: Signal<u64> }

impl TreeDataSource for MySource {
    type Item = String;
    type Key = NodeId;

    fn visible_count(&self) -> usize { 0 }
    fn with_entry<R>(&self, _i: usize, _f: impl FnOnce(&String, &FlatEntry<NodeId>) -> R) -> Option<R> { None }
    fn key_at(&self, _i: usize) -> Option<NodeId> { None }
    fn flat_index_of(&self, _k: &NodeId) -> Option<usize> { None }
    fn parent(&self, _k: &NodeId) -> Option<NodeId> { None }
    fn child_keys(&self, _k: &NodeId) -> Vec<NodeId> { vec![] }
    fn version_signal(&self) -> Signal<u64> { self.version.clone() }
    fn is_expanded(&self, _k: &NodeId) -> bool { false }
    fn set_expanded(&self, _k: &NodeId, _expanded: bool) {}
}

API reference

📖 Full rustdoc API for this module

pub struct FlatEntry

A single entry in a tree's flattened, currently-visible row list.

Generic over the key type so external sources carry their own identity (K = NodeId for TreeModel-backed sources, K = i64 for an entity-id store, …). The default K = NodeId keeps every in-tree FlatEntry mention and entry.node_id read compiling unchanged.

pub struct FlatEntry<K: ItemKey = NodeId> { /* fields */ }

pub fn tree_is_desc_or_self(...)

Whether node is ancestor or one of its descendants — the move cycle guard (you cannot drop a node into its own subtree).

pub fn tree_is_desc_or_self<T: 'static>(
    tree: &TreeModel<T>,
    node: NodeId,
    ancestor: NodeId,
) -> bool;

pub fn tree_apply_reorder(...)

Apply a tree reorder by NodeId, with the cycle guard and the remove-then-insert index adjustment TreeModel::move_node requires. Shared by the TreeSlice / SortFilterTreeModel accept_drop impls. Returns whether the move was applied (false = rejected, e.g. cycle or self-drop).

pub fn tree_apply_reorder<T: 'static>(
    tree: &TreeModel<T>,
    source: NodeId,
    target: NodeId,
    position: DropPosition,
) -> bool;