From 37397ecc6dfc9e9c6f45e53823877fabd6a132ef Mon Sep 17 00:00:00 2001
From: Pascal Kuthe <pascalkuthe@pm.me>
Date: Mon, 22 Apr 2024 02:25:18 +0200
Subject: [PATCH] tmp

---
 helix-syntax/src/injections_tree.rs | 94 +++++++++++++++++++++++++++++
 helix-syntax/src/lib.rs             |  4 +-
 2 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 helix-syntax/src/injections_tree.rs

diff --git a/helix-syntax/src/injections_tree.rs b/helix-syntax/src/injections_tree.rs
new file mode 100644
index 000000000..e181a7754
--- /dev/null
+++ b/helix-syntax/src/injections_tree.rs
@@ -0,0 +1,94 @@
+use core::slice;
+use std::iter::Peekable;
+use std::sync::Arc;
+
+use hashbrown::HashMap;
+use slotmap::{new_key_type, HopSlotMap, SlotMap};
+use tree_sitter::Tree;
+
+use crate::parse::LayerUpdateFlags;
+use crate::{HighlightConfiguration, RopeProvider};
+
+// TODO(perf): replace std::ops::Range with helix_core::Range once added
+type Range = std::ops::Range<usize>;
+
+new_key_type! {
+    /// The default slot map key type.
+    pub struct LayerId;
+}
+
+#[derive(Debug)]
+pub struct LanguageLayer {
+    pub config: Arc<HighlightConfiguration>,
+    pub(crate) parse_tree: Option<Tree>,
+    /// internal flags used during parsing to track incremental invalidation
+    pub(crate) flags: LayerUpdateFlags,
+    pub(crate) parent: Option<LayerId>,
+    /// a list of **sorted** non-overlapping injection ranges note that
+    /// injection ranges are not relative to the start of this layer but the
+    /// start of the root layer
+    pub(crate) injection_ranges: Box<[InjectionRange]>,
+}
+
+#[derive(Debug)]
+pub(crate) struct InjectionRange {
+    pub byte_range: Range,
+    pub layer: LayerId,
+}
+
+impl LanguageLayer {
+    /// Returns the injection range **within this layers** that contains `idx`.
+    /// This function will not descend into nested injections
+    pub(crate) fn injection_at_byte_idx(&self, idx: usize) -> Option<&InjectionRange> {
+        let i = self
+            .injection_ranges
+            .partition_point(|range| range.byte_range.start <= idx);
+        self.injection_ranges
+            .get(i)
+            .filter(|injection| injection.byte_range.end > idx)
+    }
+}
+
+struct InjectionTree {
+    layers: SlotMap<LayerId, LanguageLayer>,
+    root: LayerId,
+}
+
+impl InjectionTree {
+    pub fn layer_for_byte_range(&self, start: usize, end: usize) -> LayerId {
+        let mut cursor = self.root;
+        loop {
+            let layer = &self.layers[cursor];
+            let Some(start_injection) = layer.injection_at_byte_idx(start) else {
+                break;
+            };
+            let Some(end_injection) = layer.injection_at_byte_idx(end) else {
+                break;
+            };
+            if start_injection.layer == end_injection.layer {
+                cursor = start_injection.layer;
+            } else {
+                break;
+            }
+        }
+        cursor
+    }
+}
+
+struct ActiveInjection<'a> {
+    injections: Peekable<slice::Iter<'a, InjectionTree>>,
+    range: InjectionRange,
+}
+
+struct ActiveLayer<'a, State> {
+    state: State,
+    /// the query captures just for this layer
+    layer_captures: Peekable<LayerQueryCaptures<'a>>,
+}
+
+type LayerQueryCaptures<'a> = tree_sitter::QueryCaptures<'a, 'a, RopeProvider<'a>, &'a [u8]>;
+
+pub struct QueryCaptures<'a> {
+    active_layers: HashMap<LayerId, ActiveLayer<'a, ()>>,
+    active_injections: Vec<ActiveInjection<'a>>,
+}
diff --git a/helix-syntax/src/lib.rs b/helix-syntax/src/lib.rs
index 04a2d27d5..915d8df5b 100644
--- a/helix-syntax/src/lib.rs
+++ b/helix-syntax/src/lib.rs
@@ -1,5 +1,5 @@
 use ::ropey::RopeSlice;
-use slotmap::{DefaultKey as LayerId, HopSlotMap};
+use slotmap::{new_key_type, HopSlotMap};
 use tree_sitter::{Node, Parser, Point, Query, QueryCursor, Range, Tree};
 
 use std::borrow::Cow;
@@ -9,6 +9,7 @@ use std::path::Path;
 use std::str;
 use std::sync::Arc;
 
+use crate::injections_tree::LayerId;
 use crate::parse::LayerUpdateFlags;
 
 pub use crate::config::{read_query, HighlightConfiguration};
@@ -19,6 +20,7 @@ pub use tree_cursor::TreeCursor;
 
 mod config;
 pub mod highlighter;
+mod injections_tree;
 mod merge;
 mod parse;
 mod pretty_print;