7 files changed, 107 insertions, 77 deletions

diff --git a/crates/libsyntax2/src/algo/mod.rs b/crates/libsyntax2/src/algo/mod.rs
index d2de70fd4..263b58d97 100644
--- a/crates/libsyntax2/src/algo/mod.rs
+++ b/crates/libsyntax2/src/algo/mod.rs
@@ -1,4 +1,5 @@
 pub mod walk;
+pub mod visit;
 
 use {SyntaxNodeRef, TextUnit, TextRange};
 
diff --git a/crates/libsyntax2/src/algo/visit.rs b/crates/libsyntax2/src/algo/visit.rs
new file mode 100644
index 000000000..dc5afa5a9
--- /dev/null
+++ b/crates/libsyntax2/src/algo/visit.rs
@@ -0,0 +1,52 @@
+use std::marker::PhantomData;
+use {SyntaxNodeRef, AstNode, SyntaxRoot};
+
+
+pub fn visitor<'a, T>() -> impl Visitor<'a, Output=T> {
+    EmptyVisitor { ph: PhantomData }
+}
+
+pub trait Visitor<'a>: Sized {
+    type Output;
+    fn accept(self, node: SyntaxNodeRef<'a>) -> Option<Self::Output>;
+    fn visit<N, F>(self, f: F) -> Vis<Self, N, F>
+        where N: AstNode<&'a SyntaxRoot>,
+              F: FnOnce(N) -> Self::Output,
+    {
+        Vis { inner: self, f, ph: PhantomData }
+    }
+}
+
+#[derive(Debug)]
+struct EmptyVisitor<T> {
+    ph: PhantomData<fn() -> T>
+}
+
+impl<'a, T> Visitor<'a> for EmptyVisitor<T> {
+    type Output = T;
+
+    fn accept(self, _node: SyntaxNodeRef<'a>) -> Option<T> {
+        None
+    }
+}
+
+#[derive(Debug)]
+pub struct Vis<V, N, F> {
+    inner: V,
+    f: F,
+    ph: PhantomData<fn(N)>,
+}
+
+impl<'a, V, N, F> Visitor<'a> for Vis<V, N, F>
+    where
+        V: Visitor<'a>,
+        N: AstNode<&'a SyntaxRoot>,
+        F: FnOnce(N) -> <V as Visitor<'a>>::Output,
+{
+    type Output = <V as Visitor<'a>>::Output;
+
+    fn accept(self, node: SyntaxNodeRef<'a>) -> Option<Self::Output> {
+        let Vis { inner, f, .. } = self;
+        inner.accept(node).or_else(|| N::cast(node).map(f))
+    }
+}
diff --git a/crates/libsyntax2/src/ast/generated.rs b/crates/libsyntax2/src/ast/generated.rs
index 7a2a9c7d4..a4b116941 100644
--- a/crates/libsyntax2/src/ast/generated.rs
+++ b/crates/libsyntax2/src/ast/generated.rs
@@ -1,9 +1,11 @@
 use std::sync::Arc;
 use {
+    ast,
     SyntaxNode, SyntaxRoot, TreeRoot, AstNode,
     SyntaxKind::*,
 };
 
+// ConstItem
 #[derive(Debug, Clone, Copy)]
 pub struct ConstItem<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -19,15 +21,10 @@ impl<R: TreeRoot> AstNode<R> for ConstItem<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> ConstItem<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for ConstItem<R> {}
+impl<R: TreeRoot> ConstItem<R> {}
 
+// Enum
 #[derive(Debug, Clone, Copy)]
 pub struct Enum<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -43,15 +40,10 @@ impl<R: TreeRoot> AstNode<R> for Enum<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> Enum<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for Enum<R> {}
+impl<R: TreeRoot> Enum<R> {}
 
+// File
 #[derive(Debug, Clone, Copy)]
 pub struct File<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -75,6 +67,7 @@ impl<R: TreeRoot> File<R> {
     }
 }
 
+// Function
 #[derive(Debug, Clone, Copy)]
 pub struct Function<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -90,15 +83,10 @@ impl<R: TreeRoot> AstNode<R> for Function<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> Function<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for Function<R> {}
+impl<R: TreeRoot> Function<R> {}
 
+// Module
 #[derive(Debug, Clone, Copy)]
 pub struct Module<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -114,15 +102,10 @@ impl<R: TreeRoot> AstNode<R> for Module<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> Module<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for Module<R> {}
+impl<R: TreeRoot> Module<R> {}
 
+// Name
 #[derive(Debug, Clone, Copy)]
 pub struct Name<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -140,6 +123,7 @@ impl<R: TreeRoot> AstNode<R> for Name<R> {
 
 impl<R: TreeRoot> Name<R> {}
 
+// StaticItem
 #[derive(Debug, Clone, Copy)]
 pub struct StaticItem<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -155,15 +139,10 @@ impl<R: TreeRoot> AstNode<R> for StaticItem<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> StaticItem<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for StaticItem<R> {}
+impl<R: TreeRoot> StaticItem<R> {}
 
+// Struct
 #[derive(Debug, Clone, Copy)]
 pub struct Struct<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -179,15 +158,10 @@ impl<R: TreeRoot> AstNode<R> for Struct<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> Struct<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for Struct<R> {}
+impl<R: TreeRoot> Struct<R> {}
 
+// Trait
 #[derive(Debug, Clone, Copy)]
 pub struct Trait<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -203,12 +177,6 @@ impl<R: TreeRoot> AstNode<R> for Trait<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
-impl<R: TreeRoot> Trait<R> {
-    pub fn name(&self) -> Option<Name<R>> {
-        self.syntax()
-            .children()
-            .filter_map(Name::cast)
-            .next()
-    }
-}
+impl<R: TreeRoot> ast::NameOwner<R> for Trait<R> {}
+impl<R: TreeRoot> Trait<R> {}
 
diff --git a/crates/libsyntax2/src/ast/generated.rs.tera b/crates/libsyntax2/src/ast/generated.rs.tera
index 86b8b05d1..3d79b5543 100644
--- a/crates/libsyntax2/src/ast/generated.rs.tera
+++ b/crates/libsyntax2/src/ast/generated.rs.tera
@@ -1,9 +1,11 @@
 use std::sync::Arc;
 use {
+    ast,
     SyntaxNode, SyntaxRoot, TreeRoot, AstNode,
     SyntaxKind::*,
 };
 {% for node, methods in ast %}
+// {{ node }}
 #[derive(Debug, Clone, Copy)]
 pub struct {{ node }}<R: TreeRoot = Arc<SyntaxRoot>> {
     syntax: SyntaxNode<R>,
@@ -19,6 +21,12 @@ impl<R: TreeRoot> AstNode<R> for {{ node }}<R> {
     fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
 }
 
+{% if methods.traits -%}
+{%- for t in methods.traits -%}
+impl<R: TreeRoot> ast::{{ t }}<R> for {{ node }}<R> {}
+{% endfor -%}
+{%- endif -%}
+
 impl<R: TreeRoot> {{ node }}<R> {
 {%- if methods.collections -%}
 {%- for m in methods.collections -%}
diff --git a/crates/libsyntax2/src/ast/mod.rs b/crates/libsyntax2/src/ast/mod.rs
index 7d3cdb93d..56bc099fe 100644
--- a/crates/libsyntax2/src/ast/mod.rs
+++ b/crates/libsyntax2/src/ast/mod.rs
@@ -12,6 +12,15 @@ pub trait AstNode<R: TreeRoot>: Sized {
     fn syntax(&self) -> &SyntaxNode<R>;
 }
 
+pub trait NameOwner<R: TreeRoot>: AstNode<R> {
+    fn name(&self) -> Option<Name<R>> {
+        self.syntax()
+            .children()
+            .filter_map(Name::cast)
+            .next()
+    }
+}
+
 impl File<Arc<SyntaxRoot>> {
     pub fn parse(text: &str) -> Self {
         File::cast(::parse(text)).unwrap()
diff --git a/crates/libsyntax2/src/grammar.ron b/crates/libsyntax2/src/grammar.ron
index c9470d4fa..3fe8fdf0b 100644
--- a/crates/libsyntax2/src/grammar.ron
+++ b/crates/libsyntax2/src/grammar.ron
@@ -220,39 +220,25 @@ Grammar(
             ]
         ),
         "Function": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "Struct": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "Enum": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "Trait": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "Module": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "ConstItem": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "StaticItem": (
-            options: [
-                ["name", "Name"]
-            ]
+            traits: ["NameOwner"]
         ),
         "Name": (),
     },
diff --git a/crates/libsyntax2/src/yellow/syntax.rs b/crates/libsyntax2/src/yellow/syntax.rs
index 6e33310f1..a22275ed9 100644
--- a/crates/libsyntax2/src/yellow/syntax.rs
+++ b/crates/libsyntax2/src/yellow/syntax.rs
@@ -28,6 +28,12 @@ impl<R: TreeRoot> Eq for SyntaxNode<R> {}
 
 pub type SyntaxNodeRef<'a> = SyntaxNode<&'a SyntaxRoot>;
 
+#[test]
+fn syntax_node_ref_is_copy() {
+    fn assert_copy<T: Copy>(){}
+    assert_copy::<SyntaxNodeRef>()
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Hash, Ord, PartialOrd)]
 pub struct SyntaxError {
     pub msg: String,