1 files changed, 87 insertions, 0 deletions

diff --git a/src/yellow/red.rs b/src/yellow/red.rs
new file mode 100644
index 000000000..feba99faa
--- /dev/null
+++ b/src/yellow/red.rs
@@ -0,0 +1,87 @@
+use std::sync::{Arc, Weak, RwLock};
+use {
+    TextUnit, SyntaxKind, TextRange,
+    yellow::{Ptr, GreenNode, TextLen}
+};
+
+#[derive(Debug)]
+pub(crate) struct RedNode {
+    green: Arc<GreenNode>,
+    parent: Option<ParentData>,
+    children: RwLock<Vec<Option<Arc<RedNode>>>>,
+}
+
+#[derive(Debug)]
+struct ParentData {
+    parent: Ptr<RedNode>,
+    start_offset: TextUnit,
+    index_in_parent: usize,
+}
+
+impl RedNode {
+    pub fn new_root(
+        green: Arc<GreenNode>,
+    ) -> RedNode {
+        RedNode::new(green, None)
+    }
+
+    fn new_child(
+        green: Arc<GreenNode>,
+        parent: Ptr<RedNode>,
+        start_offset: TextUnit,
+        index_in_parent: usize
+    ) -> RedNode {
+        let parent_data = ParentData {
+            parent,
+            start_offset,
+            index_in_parent
+        };
+        RedNode::new(green, Some(parent_data))
+    }
+
+    fn new(
+        green: Arc<GreenNode>,
+        parent: Option<ParentData>,
+    ) -> RedNode {
+        let children = vec![None; green.n_children()];
+        RedNode { green, parent, children: RwLock::new(children) }
+    }
+
+    pub(crate) fn green(&self) -> &GreenNode {
+        &self.green
+    }
+
+    pub(crate) fn start_offset(&self) -> TextUnit {
+        match &self.parent {
+            None => 0.into(),
+            Some(p) => p.start_offset,
+        }
+    }
+
+    pub(crate) fn n_children(&self) -> usize {
+        self.green.n_children()
+    }
+
+    pub(crate) fn nth_child(&self, me: Ptr<RedNode>, n: usize) -> Arc<RedNode> {
+        match &self.children.read().unwrap()[n] {
+            Some(child) => return child.clone(),
+            None => (),
+        }
+        let mut children = self.children.write().unwrap();
+        if children[n].is_none() {
+            let start_offset = {
+                let mut acc = self.start_offset();
+                for i in 0..n {
+                    acc += self.green.nth_trivias(i).text_len();
+                    acc += self.green.nth_child(i).text_len();
+                }
+                acc += self.green.nth_trivias(n).text_len();
+                acc
+            };
+            let green = self.green.nth_child(n).clone();
+            let child = RedNode::new_child(green, me, start_offset, n);
+            children[n] = Some(Arc::new(child))
+        }
+        children[n].as_ref().unwrap().clone()
+    }
+}