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|
use std::{cmp::Reverse, ops::Range};
use super::{LanguageLayer, LayerId};
use slotmap::HopSlotMap;
use tree_sitter::Node;
/// The byte range of an injection layer.
///
/// Injection ranges may overlap, but all overlapping parts are subsets of their parent ranges.
/// This allows us to sort the ranges ahead of time in order to efficiently find a range that
/// contains a point with maximum depth.
#[derive(Debug)]
struct InjectionRange {
start: usize,
end: usize,
layer_id: LayerId,
depth: u32,
}
pub struct TreeCursor<'a> {
layers: &'a HopSlotMap<LayerId, LanguageLayer>,
root: LayerId,
current: LayerId,
injection_ranges: Vec<InjectionRange>,
// TODO: Ideally this would be a `tree_sitter::TreeCursor<'a>` but
// that returns very surprising results in testing.
cursor: Node<'a>,
}
impl<'a> TreeCursor<'a> {
pub(super) fn new(layers: &'a HopSlotMap<LayerId, LanguageLayer>, root: LayerId) -> Self {
let mut injection_ranges = Vec::new();
for (layer_id, layer) in layers.iter() {
// Skip the root layer
if layer.parent.is_none() {
continue;
}
for byte_range in layer.ranges.iter() {
let range = InjectionRange {
start: byte_range.start_byte,
end: byte_range.end_byte,
layer_id,
depth: layer.depth,
};
injection_ranges.push(range);
}
}
injection_ranges.sort_unstable_by_key(|range| (range.end, Reverse(range.depth)));
let cursor = layers[root].tree().root_node();
Self {
layers,
root,
current: root,
injection_ranges,
cursor,
}
}
pub fn node(&self) -> Node<'a> {
self.cursor
}
pub fn goto_parent(&mut self) -> bool {
if let Some(parent) = self.node().parent() {
self.cursor = parent;
return true;
}
// If we are already on the root layer, we cannot ascend.
if self.current == self.root {
return false;
}
// Ascend to the parent layer.
let range = self.node().byte_range();
let parent_id = self.layers[self.current]
.parent
.expect("non-root layers have a parent");
self.current = parent_id;
let root = self.layers[self.current].tree().root_node();
self.cursor = root
.descendant_for_byte_range(range.start, range.end)
.unwrap_or(root);
true
}
/// Finds the injection layer that has exactly the same range as the given `range`.
fn layer_id_of_byte_range(&self, search_range: Range<usize>) -> Option<LayerId> {
let start_idx = self
.injection_ranges
.partition_point(|range| range.end < search_range.end);
self.injection_ranges[start_idx..]
.iter()
.take_while(|range| range.end == search_range.end)
.find_map(|range| (range.start == search_range.start).then_some(range.layer_id))
}
pub fn goto_first_child(&mut self) -> bool {
// Check if the current node's range is an exact injection layer range.
if let Some(layer_id) = self
.layer_id_of_byte_range(self.node().byte_range())
.filter(|&layer_id| layer_id != self.current)
{
// Switch to the child layer.
self.current = layer_id;
self.cursor = self.layers[self.current].tree().root_node();
true
} else if let Some(child) = self.cursor.child(0) {
// Otherwise descend in the current tree.
self.cursor = child;
true
} else {
false
}
}
pub fn goto_next_sibling(&mut self) -> bool {
if let Some(sibling) = self.cursor.next_sibling() {
self.cursor = sibling;
true
} else {
false
}
}
pub fn goto_prev_sibling(&mut self) -> bool {
if let Some(sibling) = self.cursor.prev_sibling() {
self.cursor = sibling;
true
} else {
false
}
}
/// Finds the injection layer that contains the given start-end range.
fn layer_id_containing_byte_range(&self, start: usize, end: usize) -> LayerId {
let start_idx = self
.injection_ranges
.partition_point(|range| range.end < end);
self.injection_ranges[start_idx..]
.iter()
.take_while(|range| range.start < end)
.find_map(|range| (range.start <= start).then_some(range.layer_id))
.unwrap_or(self.root)
}
pub fn reset_to_byte_range(&mut self, start: usize, end: usize) {
self.current = self.layer_id_containing_byte_range(start, end);
let root = self.layers[self.current].tree().root_node();
self.cursor = root.descendant_for_byte_range(start, end).unwrap_or(root);
}
}
|
