make ancestors and descendants inherent

crates/ra_syntax/src/algo/mod.rs

@@ -94,10 +94,6 @@ pub fn find_covering_node(root: SyntaxNodeRef, range: TextRange) -> SyntaxNodeRe
     common_ancestor(left, right)
 }
 
-pub fn ancestors<'a>(node: SyntaxNodeRef<'a>) -> impl Iterator<Item=SyntaxNodeRef<'a>> {
-    generate(Some(node), |&node| node.parent())
-}
-
 #[derive(Debug)]
 pub enum Direction {
     Forward,
@@ -115,8 +111,8 @@ pub fn siblings<'a>(
 }
 
 fn common_ancestor<'a>(n1: SyntaxNodeRef<'a>, n2: SyntaxNodeRef<'a>) -> SyntaxNodeRef<'a> {
-    for p in ancestors(n1) {
-        if ancestors(n2).any(|a| a == p) {
+    for p in n1.ancestors() {
+        if n2.ancestors().any(|a| a == p) {
             return p;
         }
     }