Use smallvec for edges buffer in tree dfs

Signed-off-by: ITesserakt <portyas85@mail.ru>

.pre-commit-config.yaml

@@ -1 +1 @@
-/nix/store/9pk23hf63yh6wmks6x314hlyf5aw95ww-pre-commit-config.json
+/nix/store/s2r6xgybl9p1hivi3z4jhvzzs75dbbal-pre-commit-config.json

crates/kodept-ast/src/graph/syntax_tree/dfs.rs

@@ -4,6 +4,7 @@ use crate::visit_side::VisitSide;
 use slotgraph::dag::NodeKey;
 use std::collections::VecDeque;
 use std::iter::FusedIterator;
+use smallvec::SmallVec;
 
 pub enum TraverseState {
     DescendDeeper,
@@ -12,7 +13,7 @@ pub enum TraverseState {
 
 pub struct DfsIter<'a> {
     stack: VecDeque<(NodeKey, TraverseState)>,
-    edges_buffer: Vec<NodeKey>,
+    edges_buffer: SmallVec<[NodeKey; 2]>,
     graph: &'a Graph,
 }
 
@@ -23,7 +24,7 @@ impl<'a> DfsIter<'a> {
 
         Self {
             stack,
-            edges_buffer: vec![],
+            edges_buffer: SmallVec::new(),
             graph,
         }
     }

crates/kodept-ast/src/graph/syntax_tree/mod.rs

@@ -71,7 +71,7 @@ impl SyntaxTree<NoAccess> {
         id: NodeId<T>,
         token: &'b PermTkn,
         tag: ChildTag,
-    ) -> OptVec<&U>
+    ) -> OptVec<&'b U>
     where
         AnyNode: ConvertibleToRef<U>,
     {
@@ -82,23 +82,23 @@ impl SyntaxTree<NoAccess> {
             .collect()
     }
 
-    pub fn get<'b, T>(&'b self, id: NodeId<T>, token: &'b PermTkn) -> Option<&T>
+    pub fn get<'b, T>(&'b self, id: NodeId<T>, token: &'b PermTkn) -> Option<&'b T>
     where
         AnyNode: ConvertibleToRef<T>,
     {
         let node_ref = self.graph.node_weight(id.into())?;
         node_ref.ro(token).try_as_ref()
     }
 
-    pub fn get_mut<'b, T>(&'b self, id: NodeId<T>, token: &'b mut PermTkn) -> Option<&mut T>
+    pub fn get_mut<'b, T>(&'b self, id: NodeId<T>, token: &'b mut PermTkn) -> Option<&'b mut T>
     where
         AnyNode: ConvertibleToMut<T>,
     {
         let node_ref = self.graph.node_weight(id.into())?;
         node_ref.rw(token).try_as_mut()
     }
 
-    pub fn parent_of<'b, T>(&'b self, id: NodeId<T>, token: &'b PermTkn) -> Option<&AnyNode> {
+    pub fn parent_of<'b, T>(&'b self, id: NodeId<T>, token: &'b PermTkn) -> Option<&'b AnyNode> {
         let parent_id = self.graph.parent_id(id.into())?;
         Some(self.graph[parent_id].ro(token))
     }