1 files changed, 25 insertions, 3 deletions

diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 26fafb469..15a8279f3 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -21,7 +21,7 @@ pub use self::{
         AttrKind, FieldKind, PathSegmentKind, SelfParamKind, SlicePatComponents, StructKind,
         TypeBoundKind, VisibilityKind,
     },
-    generated::*,
+    generated::{nodes::*, tokens::*},
     tokens::*,
     traits::*,
 };
@@ -30,7 +30,7 @@ pub use self::{
 /// conversion itself has zero runtime cost: ast and syntax nodes have exactly
 /// the same representation: a pointer to the tree root and a pointer to the
 /// node itself.
-pub trait AstNode: std::fmt::Display {
+pub trait AstNode {
     fn can_cast(kind: SyntaxKind) -> bool
     where
         Self: Sized;
@@ -49,15 +49,37 @@ fn assert_ast_is_object_safe() {
 
 /// Like `AstNode`, but wraps tokens rather than interior nodes.
 pub trait AstToken {
-    fn cast(token: SyntaxToken) -> Option<Self>
+    fn can_cast(token: SyntaxKind) -> bool
     where
         Self: Sized;
+
+    fn cast(syntax: SyntaxToken) -> Option<Self>
+    where
+        Self: Sized;
+
     fn syntax(&self) -> &SyntaxToken;
+
     fn text(&self) -> &SmolStr {
         self.syntax().text()
     }
 }
 
+mod support {
+    use super::{AstChildren, AstNode, AstToken, SyntaxNode};
+
+    pub(super) fn child<N: AstNode>(parent: &SyntaxNode) -> Option<N> {
+        parent.children().find_map(N::cast)
+    }
+
+    pub(super) fn children<N: AstNode>(parent: &SyntaxNode) -> AstChildren<N> {
+        AstChildren::new(parent)
+    }
+
+    pub(super) fn token<T: AstToken>(parent: &SyntaxNode) -> Option<T> {
+        parent.children_with_tokens().filter_map(|it| it.into_token()).find_map(T::cast)
+    }
+}
+
 /// An iterator over `SyntaxNode` children of a particular AST type.
 #[derive(Debug, Clone)]
 pub struct AstChildren<N> {