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5b8c92b98c21f02e919d02ea69df83da65e937ad
ghostty-rs/crates/ghostty-datastruct/src/split_tree.rs
T
ddidderr 5b8c92b98c feat(unicode,datastruct): port Unicode tables and data structures 
ghostty-unicode: Ghostty computes codepoint properties with the uucode
Zig package (v0.2.0, Unicode 17.0.0). There is no Rust equivalent, so
a trimmed UCD set is vendored in ucd/ and build.rs re-implements
uucode's derivations: cell width rules incl. Ghostty's overrides for
emoji modifiers and Prepend, grapheme break classes with the
compile-time grapheme_break state table, the is_symbol set, and emoji
presentation. Lookups are three array indexes per codepoint. Validated
against the official GraphemeBreakTest.txt.

ghostty-datastruct: split_tree (used for GTK splits; f16 ratios so
rounding and debug diagrams match Zig), circ_buf, lru, cache_table,
blocking_queue, segmented_pool, message_data, comparison,
array_list_collection. intrusive_linked_list is not needed (lru is
index based). lru now reports the evicted (old) key, Zig reported the
new key, which appears to be a bug.

Not yet covered: case_folding_full (needed by input bindings).

Test Plan:
- cargo test -p ghostty-unicode (16) -p ghostty-datastruct (88)
- cargo clippy for both crates with -D warnings
2026-10-11 21:54:57 +02:00

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//! `SplitTree` represents a tree of view types that can be divided.
//!
//! Concretely for Ghostty, it represents a tree of terminal views. In
//! its basic state, there are no splits and it is a single full-sized
//! terminal. However, it can be split arbitrarily many times among two
//! axes (horizontal and vertical) to create a tree of terminal views.
//!
//! This is an immutable tree structure, meaning all operations on it
//! will return a new tree with the operation applied. This allows us to
//! store versions of the tree in a history for easy undo/redo. To facilitate
//! this, the stored View type must implement reference counting; in Rust that
//! is expressed with [`Clone`] (the Zig `ref`; e.g. `Rc<T>`, a GObject
//! handle) and [`Drop`] (the Zig `unref`).
//!
//! Optionally a view can implement [`SplitTreeView::split_tree_label`] to
//! provide a label used by the debug view. If this isn't specified then the
//! node handle will be used.
//!
//! Deviations from the Zig version: allocation is infallible (no allocator
//! parameters / `Allocator.Error`), the arena is replaced by a `Vec`, and the
//! GObject boxed-type glue (`getGObjectType`) is left to the GTK crate.
use half::f16;
use std::fmt;
/// The requirements on the view type stored in a [`SplitTree`].
pub trait SplitTreeView: Clone {
/// Return a label that is used for the debug view. If this returns
/// `None` then the node handle will be used.
fn split_tree_label(&self) -> Option<String> {
None
}
}
/// Error returned by [`SplitTree::split`] when the resulting tree would have
/// more nodes than a [`Handle`] can address (`error.OutOfMemory` in Zig).
#[derive(Debug, Clone, Copy, PartialEq, Eq, thiserror::Error)]
pub enum SplitError {
#[error("out of memory: too many nodes in split tree")]
OutOfMemory,
}
/// A handle into the nodes array. This lets us keep track of nodes with
/// 16-bit handles rather than full pointer-width values.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct Handle(u16);
impl Handle {
/// The root node (index 0).
pub const ROOT: Handle = Handle(0);
/// Create a handle from an index.
///
/// # Panics
/// If the index doesn't fit in the handle backing type.
#[must_use]
pub fn from_idx(idx: usize) -> Handle {
Handle(u16::try_from(idx).expect("split tree handle out of range"))
}
#[inline]
#[must_use]
pub fn idx(self) -> usize {
usize::from(self.0)
}
/// Offset the handle by a given amount.
#[must_use]
pub fn offset(self, v: usize) -> Handle {
let final_ = self.idx() + v;
assert!(final_ < usize::from(u16::MAX));
Handle::from_idx(final_)
}
}
#[derive(Debug, Clone)]
pub enum Node<V> {
Leaf(V),
Split(Split),
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Layout {
Horizontal,
Vertical,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Direction {
Left,
Right,
Down,
Up,
}
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct Split {
pub layout: Layout,
pub ratio: f16,
pub left: Handle,
pub right: Handle,
}
/// Alias matching the Zig `Split.Layout` / `Split.Direction` names.
pub type SplitLayout = Layout;
pub type SplitDirection = Direction;
/// A view in the tree with its handle.
#[derive(Debug, Clone, Copy)]
pub struct ViewEntry<'a, V> {
pub handle: Handle,
pub view: &'a V,
}
/// An iterator over all the views in the tree.
pub struct Iter<'a, V> {
i: usize,
nodes: &'a [Node<V>],
}
impl<'a, V> Iterator for Iter<'a, V> {
type Item = ViewEntry<'a, V>;
fn next(&mut self) -> Option<Self::Item> {
loop {
// If we have no nodes, return None.
if self.i >= self.nodes.len() {
return None;
}
// Get the current node and increment the index.
let handle = Handle::from_idx(self.i);
self.i += 1;
if let Node::Leaf(v) = &self.nodes[handle.idx()] {
return Some(ViewEntry { handle, view: v });
}
}
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Goto {
/// Previous view, null if we're the first view.
Previous,
/// Next view, null if we're the last view.
Next,
/// Previous view, but wrapped around to the last view. May
/// return the same view if this is the first view.
PreviousWrapped,
/// Next view, but wrapped around to the first view. May return
/// the same view if this is the last view.
NextWrapped,
/// A spatial direction. "Spatial" means that the direction is
/// based on the nearest surface in the given direction visually
/// as the surfaces are laid out on a 2D grid.
Spatial(SpatialDirection),
}
pub type SpatialDirection = Direction;
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Side {
Left,
Right,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[allow(clippy::enum_variant_names)]
enum Backtrack {
Deadend,
Backtrack,
Result(Handle),
}
#[derive(Debug, Clone, Copy, PartialEq)]
pub struct Slot {
pub x: f16,
pub y: f16,
pub width: f16,
pub height: f16,
}
impl Slot {
fn max_x(self) -> f16 {
self.x + self.width
}
fn max_y(self) -> f16 {
self.y + self.height
}
}
/// Spatial representation of the split tree. See [`SplitTree::spatial`].
#[derive(Debug, Clone, Default, PartialEq)]
pub struct Spatial {
/// The slots of the spatial representation in the same order
/// as the tree it was created from.
pub slots: Vec<Slot>,
}
impl Spatial {
pub const EMPTY: Spatial = Spatial { slots: Vec::new() };
}
/// Unsigned integer to f16 (`@floatFromInt`).
fn f16_from_usize(v: usize) -> f16 {
f16::from_f32(v as f32)
}
fn f16_sqrt(v: f16) -> f16 {
f16::from_f32(v.to_f32().sqrt())
}
fn f16_min(a: f16, b: f16) -> f16 {
if b < a { b } else { a }
}
fn f16_max(a: f16, b: f16) -> f16 {
if b > a { b } else { a }
}
/// See the module documentation.
#[derive(Debug, Clone)]
pub struct SplitTree<V> {
/// All the nodes in the tree. Node at index 0 is always the root.
nodes: Vec<Node<V>>,
/// The handle of the zoomed node. A "zoomed" node is one that is
/// expected to be made the full size of the split tree. Various
/// operations may unzoom (e.g. resize).
zoomed: Option<Handle>,
}
impl<V> Default for SplitTree<V> {
fn default() -> Self {
Self::empty()
}
}
impl<V> SplitTree<V> {
/// An empty tree.
#[must_use]
pub const fn empty() -> Self {
Self {
nodes: Vec::new(),
zoomed: None,
}
}
/// All nodes of the tree. Node at index 0 is the root.
#[must_use]
pub fn nodes(&self) -> &[Node<V>] {
&self.nodes
}
/// The zoomed node, if any.
#[must_use]
pub fn zoomed(&self) -> Option<Handle> {
self.zoomed
}
/// Returns true if this is an empty tree.
#[must_use]
pub fn is_empty(&self) -> bool {
// An empty tree has no nodes.
self.nodes.is_empty()
}
/// Returns true if this tree has more than one split (i.e., the root
/// is a split node). This is useful for determining if actions like
/// resize_split or toggle_split_zoom are performable.
#[must_use]
pub fn is_split(&self) -> bool {
// An empty tree is not split.
if self.is_empty() {
return false;
}
// The root node is at index 0. If it's a split, we have multiple splits.
matches!(self.nodes[0], Node::Split(_))
}
/// An iterator over all the views in the tree.
#[must_use]
pub fn iterator(&self) -> Iter<'_, V> {
Iter {
i: 0,
nodes: &self.nodes,
}
}
/// Change the zoomed state to the given node. Assumes the handle
/// is valid.
pub fn zoom(&mut self, handle: Option<Handle>) {
if let Some(v) = handle {
assert!(v.idx() < self.nodes.len());
}
self.zoomed = handle;
}
fn split_node(&self, h: Handle) -> Option<&Split> {
match &self.nodes[h.idx()] {
Node::Split(s) => Some(s),
Node::Leaf(_) => None,
}
}
/// Goto a view from a certain point in the split tree. Returns `None`
/// if the direction results in no visitable view.
#[must_use]
pub fn goto(&self, from: Handle, to: Goto) -> Option<Handle> {
match to {
Goto::Previous => self.previous(from),
Goto::Next => self.next(from),
Goto::PreviousWrapped => self
.previous(from)
.or_else(|| Some(self.deepest(Side::Right, Handle::ROOT))),
Goto::NextWrapped => self
.next(from)
.or_else(|| Some(self.deepest(Side::Left, Handle::ROOT))),
Goto::Spatial(d) => {
// Get our spatial representation.
let sp = self.spatial();
self.nearest_wrapped(&sp, from, d)
}
}
}
/// Returns the deepest view in the tree in the given direction.
/// This can be used to find the leftmost/rightmost surface within
/// a given split structure.
#[must_use]
pub fn deepest(&self, side: Side, from: Handle) -> Handle {
let mut current = from;
loop {
match &self.nodes[current.idx()] {
Node::Leaf(_) => return current,
Node::Split(s) => {
current = match side {
Side::Left => s.left,
Side::Right => s.right,
};
}
}
}
}
/// Returns the previous view from the given node handle (which itself
/// doesn't need to be a view). If there is no previous (this is the
/// most previous view) then this will return `None`.
///
/// "Previous" is defined as the previous node in an in-order
/// traversal of the tree. This isn't a perfect definition and we
/// may want to change this to something that better matches a
/// spatial view of the tree later.
fn previous(&self, from: Handle) -> Option<Handle> {
match self.previous_backtrack(from, Handle::ROOT) {
Backtrack::Result(v) => Some(v),
Backtrack::Backtrack | Backtrack::Deadend => None,
}
}
/// Same as `previous`, but returns the next view instead.
fn next(&self, from: Handle) -> Option<Handle> {
match self.next_backtrack(from, Handle::ROOT) {
Backtrack::Result(v) => Some(v),
Backtrack::Backtrack | Backtrack::Deadend => None,
}
}
// Design note: we use a recursive backtracking search because
// split trees are never that deep, so we can abuse the stack as
// a safe allocator (stack overflow unlikely unless the kernel is
// tuned in some really weird way).
fn previous_backtrack(&self, from: Handle, current: Handle) -> Backtrack {
// If we reached the point that we're trying to find the previous
// value of, then we need to backtrack from here.
if from == current {
return Backtrack::Backtrack;
}
match &self.nodes[current.idx()] {
// If we hit a leaf that isn't our target, then deadend.
Node::Leaf(_) => Backtrack::Deadend,
Node::Split(s) => match self.previous_backtrack(from, s.left) {
Backtrack::Result(v) => Backtrack::Result(v),
// Backtrack from the left means we have to continue
// backtracking because we can't see what's before the left.
Backtrack::Backtrack => Backtrack::Backtrack,
// If we hit a deadend on the left then let's move right.
Backtrack::Deadend => match self.previous_backtrack(from, s.right) {
Backtrack::Result(v) => Backtrack::Result(v),
// Deadend means its not in this split at all since
// we already tracked the left.
Backtrack::Deadend => Backtrack::Deadend,
// Backtrack means that its in our left view because
// we can see the immediate previous and there MUST
// be leaves (we can't have split-only leaves).
Backtrack::Backtrack => Backtrack::Result(self.deepest(Side::Right, s.left)),
},
},
}
}
// See previous_backtrack for detailed comments. This is a mirror of that.
fn next_backtrack(&self, from: Handle, current: Handle) -> Backtrack {
if from == current {
return Backtrack::Backtrack;
}
match &self.nodes[current.idx()] {
Node::Leaf(_) => Backtrack::Deadend,
Node::Split(s) => match self.next_backtrack(from, s.right) {
Backtrack::Result(v) => Backtrack::Result(v),
Backtrack::Backtrack => Backtrack::Backtrack,
Backtrack::Deadend => match self.next_backtrack(from, s.left) {
Backtrack::Result(v) => Backtrack::Result(v),
Backtrack::Deadend => Backtrack::Deadend,
Backtrack::Backtrack => Backtrack::Result(self.deepest(Side::Left, s.right)),
},
},
}
}
/// Returns the nearest leaf node (view) in the given direction.
/// This does not handle wrapping and will return `None` if there
/// is no node in that direction.
fn nearest(
&self,
sp: &Spatial,
from: Handle,
direction: SpatialDirection,
target: Slot,
) -> Option<Handle> {
let mut result: Option<(Handle, f16)> = None;
for (handle, slot) in sp.slots.iter().enumerate() {
// Never match ourself
if handle == from.idx() {
continue;
}
// Only match leaves
if matches!(self.nodes[handle], Node::Split(_)) {
continue;
}
// Ensure it is in the proper direction
let ok = match direction {
Direction::Left => slot.max_x() <= target.x,
Direction::Right => slot.x >= target.max_x(),
Direction::Up => slot.max_y() <= target.y,
Direction::Down => slot.y >= target.max_y(),
};
if !ok {
continue;
}
// Track our distance
let dx = slot.x - target.x;
let dy = slot.y - target.y;
let distance = f16_sqrt(dx * dx + dy * dy);
// If we have a nearest it must be closer.
if let Some((_, d)) = result
&& distance >= d
{
continue;
}
result = Some((Handle::from_idx(handle), distance));
}
result.map(|(h, _)| h)
}
/// Same as nearest but supports wrapping.
fn nearest_wrapped(
&self,
sp: &Spatial,
from: Handle,
direction: SpatialDirection,
) -> Option<Handle> {
// If we can find a nearest value without wrapping, then use that.
let mut target = sp.slots[from.idx()];
if let Some(v) = self.nearest(sp, from, direction, target) {
return Some(v);
}
// The spatial grid is normalized to 1x1, so wrapping is modeled
// by shifting the target slot by one full grid in the opposite
// direction and reusing the same nearest distance logic.
// We don't actually modify the grid or spatial representation,
// this just fakes it.
let one = f16::ONE;
assert!(target.x >= f16::ZERO && target.y >= f16::ZERO);
assert!(target.max_x() <= one && target.max_y() <= one);
match direction {
Direction::Left => target.x += one,
Direction::Right => target.x -= one,
Direction::Up => target.y += one,
Direction::Down => target.y -= one,
}
self.nearest(sp, from, direction, target)
}
/// Resize the given node in place. The node MUST be a split (asserted).
///
/// In general, this is an immutable data structure so this is
/// heavily discouraged. However, this is provided for convenience
/// and performance reasons where its very important for GUIs to
/// update the ratio during a live resize than to redraw the entire
/// widget tree.
pub fn resize_in_place(&mut self, at: Handle, ratio: f16) {
match &mut self.nodes[at.idx()] {
Node::Split(s) => s.ratio = ratio,
Node::Leaf(_) => panic!("resize_in_place on a leaf node"),
}
}
/// Returns the number of nodes that would be needed to store
/// the tree if the target node is removed.
fn count_after_removal(&self, current: Handle, target: Handle, acc: usize) -> usize {
assert_ne!(current, target);
match &self.nodes[current.idx()] {
// Leaf is simple, always takes one node.
Node::Leaf(_) => acc + 1,
// Split is slightly more complicated. If either side is the
// target to remove, then we remove the split node as well
// so our count is just the count of the other side.
//
// If neither side is the target, then we count both sides
// and add one to account for the split node itself.
Node::Split(s) => {
if s.left == target {
self.count_after_removal(s.right, target, acc)
} else if s.right == target {
self.count_after_removal(s.left, target, acc)
} else {
self.count_after_removal(s.left, target, acc)
+ self.count_after_removal(s.right, target, acc)
+ 1
}
}
}
}
fn weight(&self, from: Handle, layout: Layout, acc: usize) -> usize {
match &self.nodes[from.idx()] {
Node::Leaf(_) => acc + 1,
Node::Split(s) => {
if s.layout == layout {
self.weight(s.left, layout, acc) + self.weight(s.right, layout, acc)
} else {
1
}
}
}
}
fn find_parent_split(&self, layout: Layout, from: Handle, current: Handle) -> Backtrack {
if from == current {
return Backtrack::Backtrack;
}
match &self.nodes[current.idx()] {
Node::Leaf(_) => Backtrack::Deadend,
Node::Split(s) => match self.find_parent_split(layout, from, s.left) {
Backtrack::Result(v) => Backtrack::Result(v),
Backtrack::Backtrack => {
if s.layout == layout {
Backtrack::Result(current)
} else {
Backtrack::Backtrack
}
}
Backtrack::Deadend => match self.find_parent_split(layout, from, s.right) {
Backtrack::Deadend => Backtrack::Deadend,
Backtrack::Result(v) => Backtrack::Result(v),
Backtrack::Backtrack => {
if s.layout == layout {
Backtrack::Result(current)
} else {
Backtrack::Backtrack
}
}
},
},
}
}
/// Spatial representation of the split tree. This can be used to
/// better understand the layout of the tree in a 2D space.
///
/// The bounds of the representation are always based on the total
/// 2D space being 1x1. The x/y coordinates and width/height dimensions
/// of each individual split and leaf are relative to this.
/// This means that the spatial representation is a normalized
/// representation of the actual space.
///
/// The top-left corner of the tree is always (0, 0).
///
/// We use a normalized form because we can calculate it without
/// accessing to the actual rendered view sizes. These actual sizes
/// may not be available at various times because GUI toolkits often
/// only make them available once they're part of a widget tree and
/// a SplitTree can represent views that aren't currently visible.
#[must_use]
pub fn spatial(&self) -> Spatial {
// No nodes, empty spatial representation.
if self.nodes.is_empty() {
return Spatial::EMPTY;
}
// Get our total dimensions.
let (dim_w, dim_h) = self.dimensions(Handle::ROOT);
// Create our slots which will match our nodes exactly.
let zero = Slot {
x: f16::ZERO,
y: f16::ZERO,
width: f16::ZERO,
height: f16::ZERO,
};
let mut slots = vec![zero; self.nodes.len()];
slots[0] = Slot {
x: f16::ZERO,
y: f16::ZERO,
width: f16_from_usize(usize::from(dim_w)),
height: f16_from_usize(usize::from(dim_h)),
};
self.fill_spatial_slots(&mut slots, Handle::ROOT);
// Normalize the dimensions to 1x1 grid.
let fw = f16_from_usize(usize::from(dim_w));
let fh = f16_from_usize(usize::from(dim_h));
for slot in &mut slots {
slot.x /= fw;
slot.y /= fh;
slot.width /= fw;
slot.height /= fh;
}
Spatial { slots }
}
fn fill_spatial_slots(&self, slots: &mut [Slot], current_: Handle) {
let current = current_.idx();
assert!(slots[current].width >= f16::ZERO && slots[current].height >= f16::ZERO);
match &self.nodes[current] {
// Leaf node, current slot is already filled by caller.
Node::Leaf(_) => {}
Node::Split(s) => {
let cur = slots[current];
let one = f16::ONE;
match s.layout {
Layout::Horizontal => {
slots[s.left.idx()] = Slot {
x: cur.x,
y: cur.y,
width: cur.width * s.ratio,
height: cur.height,
};
slots[s.right.idx()] = Slot {
x: cur.x + cur.width * s.ratio,
y: cur.y,
width: cur.width * (one - s.ratio),
height: cur.height,
};
}
Layout::Vertical => {
slots[s.left.idx()] = Slot {
x: cur.x,
y: cur.y,
width: cur.width,
height: cur.height * s.ratio,
};
slots[s.right.idx()] = Slot {
x: cur.x,
y: cur.y + cur.height * s.ratio,
width: cur.width,
height: cur.height * (one - s.ratio),
};
}
}
self.fill_spatial_slots(slots, s.left);
self.fill_spatial_slots(slots, s.right);
}
}
}
/// Get the dimensions of the tree starting from the given node.
///
/// This creates relative dimensions (see Spatial) by assuming each
/// leaf is exactly 1x1 unit in size. Returns `(width, height)`.
fn dimensions(&self, current: Handle) -> (u16, u16) {
match &self.nodes[current.idx()] {
Node::Leaf(_) => (1, 1),
Node::Split(s) => {
let left = self.dimensions(s.left);
let right = self.dimensions(s.right);
match s.layout {
Layout::Horizontal => (left.0 + right.0, left.1.max(right.1)),
Layout::Vertical => (left.0.max(right.0), left.1 + right.1),
}
}
}
}
}
impl<V: SplitTreeView> SplitTree<V> {
/// Initialize a new tree with a single view. The view is referenced
/// (cloned) by the tree.
#[must_use]
pub fn new(view: &V) -> Self {
Self {
nodes: vec![Node::Leaf(view.clone())],
zoomed: None,
}
}
/// Insert another tree into this tree at the given node in the
/// specified direction. The other tree will be inserted in the
/// new direction. For example, if the direction is "right" then
/// `insert` is inserted right of the existing node.
///
/// The previous trees are not modified, but reference counts for the
/// views will be increased accordingly for the new tree.
pub fn split(
&self,
at: Handle,
direction: Direction,
ratio: f16,
insert: &Self,
) -> Result<Self, SplitError> {
// We know we're going to need the sum total of the nodes
// between the two trees plus one for the new split node.
let total = self.nodes.len() + insert.nodes.len() + 1;
if total > usize::from(u16::MAX) {
return Err(SplitError::OutOfMemory);
}
// We can copy our nodes exactly as they are, since they're
// mostly not changing (only `at` is changing). We can copy the
// destination nodes as well directly next to the source nodes. We
// just have to go through and offset all the handles in the
// destination tree to account for the shift.
let mut nodes: Vec<Node<V>> = Vec::with_capacity(total);
nodes.extend(self.nodes.iter().cloned());
for node in &insert.nodes {
nodes.push(match node {
Node::Leaf(v) => Node::Leaf(v.clone()),
Node::Split(s) => Node::Split(Split {
left: s.left.offset(self.nodes.len()),
right: s.right.offset(self.nodes.len()),
..*s
}),
});
}
// Determine our split layout and if we're on the left
let (layout, left) = match direction {
Direction::Left => (Layout::Horizontal, true),
Direction::Right => (Layout::Horizontal, false),
Direction::Up => (Layout::Vertical, true),
Direction::Down => (Layout::Vertical, false),
};
// Copy our previous value to the end of the nodes list and
// create our new split node.
let prev = nodes[at.idx()].clone();
nodes.push(prev);
let last = nodes.len() - 1;
let (l, r) = if left {
(self.nodes.len(), last)
} else {
(last, self.nodes.len())
};
nodes[at.idx()] = Node::Split(Split {
layout,
ratio,
left: Handle::from_idx(l),
right: Handle::from_idx(r),
});
Ok(Self {
nodes,
// Splitting always resets zoom state.
zoomed: None,
})
}
/// Remove a node from the tree.
#[must_use]
pub fn remove(&self, at: Handle) -> Self {
assert!(at.idx() < self.nodes.len());
// If we're removing node zero then we're clearing the tree.
if at == Handle::ROOT {
return Self::empty();
}
// Allocate our new nodes list with the number of nodes we'll
// need after the removal.
let count = self.count_after_removal(Handle::ROOT, at, 0);
let mut new_nodes: Vec<Option<Node<V>>> = (0..count).map(|_| None).collect();
let mut new_zoomed = None;
// Traverse the tree and copy all our nodes into place.
assert!(self.remove_node(&mut new_nodes, &mut new_zoomed, 0, Handle::ROOT, at) != 0);
Self {
nodes: new_nodes
.into_iter()
.map(|n| n.expect("all nodes filled by remove"))
.collect(),
zoomed: new_zoomed,
}
}
fn remove_node(
&self,
new_nodes: &mut [Option<Node<V>>],
new_zoomed: &mut Option<Handle>,
new_offset: usize,
current: Handle,
target: Handle,
) -> usize {
assert_ne!(current, target);
// If we have a zoomed node and this is it then we migrate it.
if let Some(v) = self.zoomed
&& v == current
{
assert!(new_zoomed.is_none());
*new_zoomed = Some(Handle::from_idx(new_offset));
}
match &self.nodes[current.idx()] {
// Leaf is simple, just copy it over (cloning is the ref).
Node::Leaf(view) => {
new_nodes[new_offset] = Some(Node::Leaf(view.clone()));
1
}
Node::Split(s) => {
// If we're removing one of the split node sides then
// we remove the split node itself as well and only add
// the other (non-removed) side.
if s.left == target {
return self.remove_node(new_nodes, new_zoomed, new_offset, s.right, target);
}
if s.right == target {
return self.remove_node(new_nodes, new_zoomed, new_offset, s.left, target);
}
// Neither side is being directly removed, so we traverse.
let left = self.remove_node(new_nodes, new_zoomed, new_offset + 1, s.left, target);
assert!(left != 0);
let right = self.remove_node(
new_nodes,
new_zoomed,
new_offset + left + 1,
s.right,
target,
);
assert!(right != 0);
new_nodes[new_offset] = Some(Node::Split(Split {
layout: s.layout,
ratio: s.ratio,
left: Handle::from_idx(new_offset + 1),
right: Handle::from_idx(new_offset + 1 + left),
}));
left + right + 1
}
}
}
/// Equalize this node and all its children, returning a new node with splits
/// adjusted so that each split's ratio is based on the relative weight
/// (number of leaves) of its children.
#[must_use]
pub fn equalize(&self) -> Self {
if self.is_empty() {
return Self::empty();
}
// Copy the existing nodes (cloning the views).
let mut nodes = self.nodes.clone();
// Go through and equalize our ratios based on weights.
for node in &mut nodes {
if let Node::Split(s) = node {
let weight_left = self.weight(s.left, s.layout, 0);
let weight_right = self.weight(s.right, s.layout, 0);
assert!(weight_left > 0);
assert!(weight_right > 0);
let total_f16 = f16_from_usize(weight_left + weight_right);
let weight_left_f16 = f16_from_usize(weight_left);
s.ratio = weight_left_f16 / total_f16;
}
}
Self {
nodes,
zoomed: self.zoomed,
}
}
/// Resize the nearest split matching the layout by the given ratio.
/// Positive is right and down.
///
/// The ratio is a signed delta representing the percentage to move
/// the divider. The percentage is of the entire grid size, not just
/// the specific split size.
/// We use the entire grid size because that's what Ghostty's
/// `resize_split` keybind does, because it maps to a general human
/// understanding of moving a split relative to the entire window
/// (generally).
///
/// For example, a ratio of 0.1 and a layout of `vertical` will find
/// the nearest vertical split and move the divider down by 10% of
/// the total grid height.
///
/// If no matching split is found, this does nothing, but will always
/// still return a cloned tree.
#[must_use]
pub fn resize(&self, from: Handle, layout: Layout, ratio: f16) -> Self {
assert!(ratio >= f16::from_f32(-1.0) && ratio <= f16::ONE);
assert!(!ratio.is_nan());
assert!(!ratio.is_infinite());
// Fast path empty trees.
if self.is_empty() {
return Self::empty();
}
// From this point forward worst case we return a clone.
let mut result = self.clone();
// Find our nearest parent split node matching the layout.
let parent_handle = match self.find_parent_split(layout, from, Handle::ROOT) {
Backtrack::Deadend | Backtrack::Backtrack => return result,
Backtrack::Result(v) => v,
};
// Get our spatial layout, because we need the dimensions of this
// split with regards to the entire grid.
let sp = result.spatial();
// Get the ratio of the split relative to the full grid.
let full_ratio = {
// Our scale is the amount we need to multiply our individual
// ratio by to get the full ratio. Its actually a ratio on its
// own but I'm trying to avoid that word: its the ratio of
// our spatial width/height to the total.
let scale = match layout {
Layout::Horizontal => sp.slots[parent_handle.idx()].width / sp.slots[0].width,
Layout::Vertical => sp.slots[parent_handle.idx()].height / sp.slots[0].height,
};
let current = result
.split_node(parent_handle)
.expect("parent is a split")
.ratio;
current * scale
};
// Set the final new ratio, clamping it to [0, 1]
result.resize_in_place(
parent_handle,
f16_min(f16_max(full_ratio + ratio, f16::ZERO), f16::ONE),
);
result
}
/// Format the tree in a human-readable format. By default this will
/// output a diagram followed by a textual representation.
fn format_all(&self, w: &mut dyn fmt::Write) -> fmt::Result {
if self.nodes.is_empty() {
return w.write_str("empty");
}
let _ = self.format_diagram(w);
self.format_text(w)
}
/// Text representation of the tree.
pub fn format_text(&self, w: &mut dyn fmt::Write) -> fmt::Result {
if self.nodes.is_empty() {
return w.write_str("empty");
}
self.format_text_inner(w, Handle::ROOT, 0)
}
fn format_text_inner(
&self,
w: &mut dyn fmt::Write,
current: Handle,
depth: usize,
) -> fmt::Result {
for _ in 0..depth {
w.write_str(" ")?;
}
if let Some(zoomed) = self.zoomed
&& zoomed == current
{
w.write_str("(zoomed) ")?;
}
match &self.nodes[current.idx()] {
Node::Leaf(v) => match v.split_tree_label() {
Some(label) => writeln!(w, "leaf: {label}"),
None => writeln!(w, "leaf: {}", current.idx()),
},
Node::Split(s) => {
let layout = match s.layout {
Layout::Horizontal => "horizontal",
Layout::Vertical => "vertical",
};
writeln!(
w,
"split (layout: {layout}, ratio: {:.2})",
s.ratio.to_f32()
)?;
self.format_text_inner(w, s.left, depth + 1)?;
self.format_text_inner(w, s.right, depth + 1)
}
}
}
/// ASCII-art diagram of the tree.
#[allow(clippy::too_many_lines)]
pub fn format_diagram(&self, w: &mut dyn fmt::Write) -> fmt::Result {
if self.nodes.is_empty() {
return w.write_str("empty");
}
// Get our spatial representation.
let sp = {
let sp = self.spatial();
// Scale our spatial representation to have minimum width/height 1.
let mut min_w = f16::ONE;
let mut min_h = f16::ONE;
for slot in &sp.slots {
if slot.width > f16::ZERO {
min_w = f16_min(min_w, slot.width);
}
if slot.height > f16::ZERO {
min_h = f16_min(min_h, slot.height);
}
}
let ratio_w = f16::ONE / min_w;
let ratio_h = f16::ONE / min_h;
let mut slots = sp.slots.clone();
for slot in &mut slots {
slot.x *= ratio_w;
slot.y *= ratio_h;
slot.width *= ratio_w;
slot.height *= ratio_h;
}
Spatial { slots }
};
let label_of = |handle: usize, node: &Node<V>| -> Option<String> {
match node {
Node::Split(_) => None,
Node::Leaf(v) => Some(v.split_tree_label().unwrap_or_else(|| handle.to_string())),
}
};
// The width we need for the largest label.
let max_label_width: usize = {
let mut max = 0;
let mut any_label = false;
for node in &self.nodes {
if let Node::Leaf(v) = node
&& let Some(label) = v.split_tree_label()
{
any_label = true;
max = max.max(label.len());
}
}
if any_label {
max
} else {
(sp.slots.len().ilog10() + 1) as usize
}
};
// We need space for whitespace and ASCII art so add that.
// Border + whitespace + label + whitespace + border.
let cell_width = 2 + max_label_width + 2;
// Border + label + border. No whitespace needed on the vertical axis.
let cell_height = 1 + 1 + 1;
// Make a grid that can fit our entire ASCII diagram. We know
// the width/height based on node 0.
let mut grid: Vec<Vec<u8>> = {
// Get our initial width/height. Each leaf is 1x1 in this.
// We round up for this because partial widths/heights should
// take up an extra cell.
let mut width = sp.slots[0].width.to_f32().ceil() as usize;
let mut height = sp.slots[0].height.to_f32().ceil() as usize;
width *= cell_width;
height *= cell_height;
(0..height)
.map(|_| {
let mut row = vec![b' '; width + 1];
row[width] = b'\n';
row
})
.collect()
};
// Draw each node
for (handle, slot) in sp.slots.iter().enumerate() {
// We only draw leaf nodes. Splits are only used for layout.
let node = &self.nodes[handle];
let Some(label) = label_of(handle, node) else {
continue;
};
// If our width/height is zero then we skip this.
if slot.width == f16::ZERO || slot.height == f16::ZERO {
continue;
}
let mut x = slot.x.to_f32().floor() as usize;
let mut y = slot.y.to_f32().floor() as usize;
let mut width = slot.width.to_f32().floor().max(1.0) as usize;
let mut height = slot.height.to_f32().floor().max(1.0) as usize;
x *= cell_width;
y *= cell_height;
width *= cell_width;
height *= cell_height;
// Top border
{
let top = &mut grid[y][x..x + width];
top[0] = b'+';
for c in &mut top[1..width - 1] {
*c = b'-';
}
top[width - 1] = b'+';
}
// Bottom border
{
let bottom = &mut grid[y + height - 1][x..x + width];
bottom[0] = b'+';
for c in &mut bottom[1..width - 1] {
*c = b'-';
}
bottom[width - 1] = b'+';
}
// Left and right borders
for row in &mut grid[y + 1..y + height - 1] {
row[x] = b'|';
}
for row in &mut grid[y + 1..y + height - 1] {
row[x + width - 1] = b'|';
}
// Draw the handle in the center
let x_mid = width / 2 + x;
let y_mid = height / 2 + y;
let label_width = label.len();
let label_start = x_mid - label_width / 2;
let row = &mut grid[y_mid][label_start..];
if label.len() > row.len() {
return Err(fmt::Error);
}
row[..label.len()].copy_from_slice(label.as_bytes());
}
// Output every row
for row in &grid {
// We currently have a bug in our height calculation that
// results in trailing blank lines. Ignore those. We should
// really fix our height calculation instead. If someone wants
// to do that just remove this line and see the tests that fail
// and go from there.
if row[0] == b' ' {
break;
}
w.write_str(&String::from_utf8_lossy(row))?;
}
Ok(())
}
/// The diagram as a string (the Zig `{f}` of `std.fmt.alt(t, .formatDiagram)`).
#[must_use]
pub fn diagram_string(&self) -> String {
let mut s = String::new();
let _ = self.format_diagram(&mut s);
s
}
/// The text representation as a string (`.formatText`).
#[must_use]
pub fn text_string(&self) -> String {
let mut s = String::new();
let _ = self.format_text(&mut s);
s
}
}
impl<V: SplitTreeView> fmt::Display for SplitTree<V> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut s = String::new();
self.format_all(&mut s)?;
f.write_str(&s)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[derive(Debug, Clone)]
struct TestView {
label: &'static str,
}
impl SplitTreeView for TestView {
fn split_tree_label(&self) -> Option<String> {
Some(self.label.to_string())
}
}
type TestTree = SplitTree<TestView>;
fn v(label: &'static str) -> TestView {
TestView { label }
}
fn h(f: f32) -> f16 {
f16::from_f32(f)
}
fn find(t: &TestTree, label: &str) -> Handle {
t.iterator()
.find(|e| e.view.label == label)
.expect("not found")
.handle
}
fn leaf_label(t: &TestTree, handle: Handle) -> &'static str {
match &t.nodes()[handle.idx()] {
Node::Leaf(v) => v.label,
Node::Split(_) => panic!("not a leaf"),
}
}
#[test]
fn split_tree_is_split() {
// Empty tree should not be split
let empty = TestTree::empty();
assert!(!empty.is_split());
// Single node tree should not be split
let single = TestTree::new(&v("A"));
assert!(!single.is_split());
// Split tree should be split
let tree2 = TestTree::new(&v("B"));
let split = single
.split(Handle::ROOT, Direction::Right, h(0.5), &tree2)
.unwrap();
assert!(split.is_split());
}
#[test]
fn split_tree_empty_tree() {
let t = TestTree::empty();
assert_eq!(t.to_string(), "empty");
}
#[test]
fn split_tree_single_node() {
let t = TestTree::new(&v("A"));
assert_eq!(t.diagram_string(), "+---+\n| A |\n+---+\n");
}
#[test]
fn split_tree_split_horizontal() {
let t1 = TestTree::new(&v("A"));
let t2 = TestTree::new(&v("B"));
let t3 = t1
.split(Handle::ROOT, Direction::Right, h(0.5), &t2)
.unwrap();
assert_eq!(
t3.to_string(),
"+---++---+\n\
| A || B |\n\
+---++---+\n\
split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: A\n\
\x20 leaf: B\n"
);
// Split right at B
let tc = TestTree::new(&v("C"));
let t4 = t3
.split(find(&t3, "B"), Direction::Right, h(0.5), &tc)
.unwrap();
assert_eq!(
t4.to_string(),
"+--------++---++---+\n\
| A || B || C |\n\
+--------++---++---+\n\
split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: A\n\
\x20 split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: B\n\
\x20 leaf: C\n"
);
// Split right at C
let td = TestTree::new(&v("D"));
let t5 = t4
.split(find(&t4, "C"), Direction::Right, h(0.5), &td)
.unwrap();
assert_eq!(
t5.to_string(),
"+------------------++--------++---++---+\n\
| A || B || C || D |\n\
+------------------++--------++---++---+\n\
split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: A\n\
\x20 split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: B\n\
\x20 split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: C\n\
\x20 leaf: D\n"
);
// Find "previous" from D back.
let mut current = b'D';
while current != b'A' {
let label = (current as char).to_string();
let handle = t5.previous(find(&t5, &label)).unwrap();
assert_eq!(leaf_label(&t5, handle).as_bytes(), &[current - 1]);
current -= 1;
}
assert!(t5.previous(find(&t5, "A")).is_none());
// Find "next" from A forward.
let mut current = b'A';
while current != b'D' {
let label = (current as char).to_string();
let handle = t5.next(find(&t5, &label)).unwrap();
assert_eq!(leaf_label(&t5, handle).as_bytes(), &[current + 1]);
current += 1;
}
assert!(t5.next(find(&t5, "D")).is_none());
}
#[test]
fn split_tree_split_vertical() {
let t1 = TestTree::new(&v("A"));
let t2 = TestTree::new(&v("B"));
let t3 = t1
.split(Handle::ROOT, Direction::Down, h(0.5), &t2)
.unwrap();
assert_eq!(
t3.diagram_string(),
"+---+\n| A |\n+---+\n+---+\n| B |\n+---+\n"
);
}
fn ab_split(dir: Direction, ratio: f32) -> TestTree {
let t1 = TestTree::new(&v("A"));
let t2 = TestTree::new(&v("B"));
t1.split(Handle::ROOT, dir, h(ratio), &t2).unwrap()
}
#[test]
fn split_tree_split_horizontal_with_zero_ratio() {
assert_eq!(
ab_split(Direction::Right, 0.0).diagram_string(),
"+---+\n| B |\n+---+\n"
);
}
#[test]
fn split_tree_split_vertical_with_zero_ratio() {
assert_eq!(
ab_split(Direction::Down, 0.0).diagram_string(),
"+---+\n| B |\n+---+\n"
);
}
#[test]
fn split_tree_split_horizontal_with_full_width() {
assert_eq!(
ab_split(Direction::Right, 1.0).diagram_string(),
"+---+\n| A |\n+---+\n"
);
}
#[test]
fn split_tree_split_vertical_with_full_width() {
assert_eq!(
ab_split(Direction::Down, 1.0).diagram_string(),
"+---+\n| A |\n+---+\n"
);
}
#[test]
fn split_tree_remove_leaf() {
let t3 = ab_split(Direction::Right, 0.5);
let t4 = t3.remove(find(&t3, "A"));
assert_eq!(t4.diagram_string(), "+---+\n| B |\n+---+\n");
}
#[test]
fn split_tree_split_twice_remove_intermediary() {
let t3 = TestTree::new(&v("C"));
// A | B horizontal.
let split1 = ab_split(Direction::Right, 0.5);
// Insert C below that.
let split2 = split1
.split(Handle::ROOT, Direction::Down, h(0.5), &t3)
.unwrap();
assert_eq!(
split2.diagram_string(),
"+---++---+\n\
| A || B |\n\
+---++---+\n\
+--------+\n\
| C |\n\
+--------+\n"
);
// Remove "B"
let split3 = split2.remove(find(&split2, "B"));
assert_eq!(
split3.diagram_string(),
"+---+\n| A |\n+---+\n+---+\n| C |\n+---+\n"
);
// Remove every node from split2 (our most complex one), which should
// never crash. We don't test the result is correct, this just verifies
// we don't hit any assertion failures.
for i in 0..split2.nodes().len() {
let _ = split2.remove(Handle::from_idx(i));
}
}
#[test]
fn split_tree_spatial_goto() {
let t1 = TestTree::new(&v("A"));
let t2 = TestTree::new(&v("B"));
let t3 = TestTree::new(&v("C"));
let t4 = TestTree::new(&v("D"));
// A | B horizontal
let split_ab = t1
.split(Handle::ROOT, Direction::Right, h(0.5), &t2)
.unwrap();
// A | C vertical
let split_ac = split_ab
.split(find(&split_ab, "A"), Direction::Down, h(0.8), &t3)
.unwrap();
// B | D vertical
let split = split_ac
.split(find(&split_ab, "B"), Direction::Down, h(0.3), &t4)
.unwrap();
assert_eq!(
split.diagram_string(),
"+---++---+\n\
| || B |\n\
| |+---+\n\
| |+---+\n\
| A || |\n\
| || |\n\
| || |\n\
| || D |\n\
+---+| |\n\
+---+| |\n\
| C || |\n\
+---++---+\n"
);
let go = |from: &str, dir: Direction| {
let target = split
.goto(find(&split, from), Goto::Spatial(dir))
.expect("target");
leaf_label(&split, target)
};
// Spatial C => right
assert_eq!(go("C", Direction::Right), "D");
// Spatial D => left
assert_eq!(go("D", Direction::Left), "A");
// Spatial A => left (wrapped)
assert_eq!(go("A", Direction::Left), "B");
// Spatial B => right (wrapped)
assert_eq!(go("B", Direction::Right), "A");
// Spatial C => down (wrapped)
assert_eq!(go("C", Direction::Down), "A");
// Equalize
let equal = split.equalize();
assert_eq!(
equal.diagram_string(),
"+---++---+\n\
| A || B |\n\
+---++---+\n\
+---++---+\n\
| C || D |\n\
+---++---+\n"
);
}
#[test]
fn split_tree_resize() {
let split = ab_split(Direction::Right, 0.5);
assert_eq!(
split.diagram_string(),
"+---++---+\n| A || B |\n+---++---+\n"
);
// Resize
{
let resized = split.resize(find(&split, "B"), Layout::Horizontal, h(0.25));
assert_eq!(
resized.diagram_string(),
"+-------------++---+\n\
| A || B |\n\
+-------------++---+\n"
);
}
// Resize the other direction (negative ratio)
{
let resized = split.resize(find(&split, "B"), Layout::Horizontal, h(-0.25));
assert_eq!(
resized.diagram_string(),
"+---++-------------+\n\
| A || B |\n\
+---++-------------+\n"
);
}
}
#[test]
fn split_tree_clone_empty_tree() {
let t = TestTree::empty();
let t2 = t.clone();
assert_eq!(t2.to_string(), "empty");
}
#[test]
fn split_tree_zoom() {
let mut split = ab_split(Direction::Right, 0.5);
let b = find(&split, "B");
split.zoom(Some(b));
let expected = "split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: A\n\
\x20 (zoomed) leaf: B\n";
assert_eq!(split.text_string(), expected);
// Clone preserves zoom
let clone = split.clone();
assert_eq!(clone.text_string(), expected);
}
#[test]
fn split_tree_split_resets_zoom() {
let mut t1 = TestTree::new(&v("A"));
let t2 = TestTree::new(&v("B"));
// Zoom A
let a = find(&t1, "A");
t1.zoom(Some(a));
let split = t1
.split(Handle::ROOT, Direction::Right, h(0.5), &t2)
.unwrap();
assert_eq!(
split.text_string(),
"split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: A\n\
\x20 leaf: B\n"
);
}
#[test]
fn split_tree_remove_and_zoom() {
let mut split = ab_split(Direction::Right, 0.5);
let a = find(&split, "A");
split.zoom(Some(a));
// Remove A, should unzoom
{
let removed = split.remove(find(&split, "A"));
assert!(removed.zoomed().is_none());
assert_eq!(removed.text_string(), "leaf: B\n");
}
// Remove B, should keep zoom
{
let removed = split.remove(find(&split, "B"));
assert_eq!(removed.text_string(), "(zoomed) leaf: A\n");
}
}
// Extra tests beyond the Zig suite.
#[test]
fn split_tree_goto_linear() {
let mut t = TestTree::new(&v("A"));
for l in ["B", "C"] {
let n = TestTree::new(&v(l));
let at = find(&t, if l == "B" { "A" } else { "B" });
t = t.split(at, Direction::Right, h(0.5), &n).unwrap();
}
let a = find(&t, "A");
let c = find(&t, "C");
assert_eq!(t.goto(a, Goto::Previous), None);
assert_eq!(t.goto(c, Goto::Next), None);
assert_eq!(t.goto(a, Goto::PreviousWrapped), Some(c));
assert_eq!(t.goto(c, Goto::NextWrapped), Some(a));
assert_eq!(leaf_label(&t, t.goto(a, Goto::Next).unwrap()), "B");
}
#[test]
fn split_tree_split_too_many_nodes() {
// 2^15 each would exceed u16 handles.
let big = SplitTree {
nodes: vec![Node::Leaf(v("X")); 40_000],
zoomed: None,
};
let err = big
.split(Handle::ROOT, Direction::Right, h(0.5), &big)
.unwrap_err();
assert_eq!(err, SplitError::OutOfMemory);
}
#[test]
fn split_tree_default_label_uses_handle() {
#[derive(Clone)]
struct Plain;
impl SplitTreeView for Plain {}
let a = SplitTree::new(&Plain);
let b = SplitTree::new(&Plain);
let s = a.split(Handle::ROOT, Direction::Right, h(0.5), &b).unwrap();
assert_eq!(
s.to_string(),
"+---++---+\n\
| 2 || 1 |\n\
+---++---+\n\
split (layout: horizontal, ratio: 0.50)\n\
\x20 leaf: 2\n\
\x20 leaf: 1\n"
);
}
#[test]
fn split_tree_ref_counts_follow_clones() {
use std::rc::Rc;
#[derive(Clone)]
#[allow(dead_code)]
struct Rcv(Rc<()>);
impl SplitTreeView for Rcv {}
let rc = Rc::new(());
let a = SplitTree::new(&Rcv(rc.clone()));
assert_eq!(Rc::strong_count(&rc), 2);
let b = SplitTree::new(&Rcv(rc.clone()));
let s = a.split(Handle::ROOT, Direction::Right, h(0.5), &b).unwrap();
assert_eq!(Rc::strong_count(&rc), 5);
drop(a);
drop(b);
assert_eq!(Rc::strong_count(&rc), 3);
drop(s);
assert_eq!(Rc::strong_count(&rc), 1);
}
}
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