3 files changed, 106 insertions, 95 deletions

diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index 9950ab12d..beef2c6e2 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -1,6 +1,7 @@
 //! Abstract Syntax Tree, layered on top of untyped `SyntaxNode`s
 mod generated;
 mod traits;
+mod tokens;
 
 use std::marker::PhantomData;
 
@@ -15,6 +16,7 @@ use crate::{
 pub use self::{
     generated::*,
     traits::*,
+    tokens::*,
 };
 
 /// The main trait to go from untyped `SyntaxNode`  to a typed ast. The
@@ -49,6 +51,16 @@ impl<'a, N: AstNode + 'a> Iterator for AstChildren<'a, N> {
     }
 }
 
+pub trait AstToken<'a> {
+    fn cast(token: SyntaxToken<'a>) -> Option<Self>
+    where
+        Self: Sized;
+    fn syntax(&self) -> SyntaxToken<'a>;
+    fn text(&self) -> &'a SmolStr {
+        self.syntax().text()
+    }
+}
+
 impl Attr {
     pub fn is_inner(&self) -> bool {
         let tt = match self.value() {
@@ -96,100 +108,6 @@ impl Attr {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
-pub struct Comment<'a>(SyntaxToken<'a>);
-
-impl<'a> Comment<'a> {
-    pub fn cast(token: SyntaxToken<'a>) -> Option<Self> {
-        if token.kind() == COMMENT {
-            Some(Comment(token))
-        } else {
-            None
-        }
-    }
-
-    pub fn syntax(&self) -> SyntaxToken<'a> {
-        self.0
-    }
-
-    pub fn text(&self) -> &'a SmolStr {
-        self.0.text()
-    }
-
-    pub fn flavor(&self) -> CommentFlavor {
-        let text = self.text();
-        if text.starts_with("///") {
-            CommentFlavor::Doc
-        } else if text.starts_with("//!") {
-            CommentFlavor::ModuleDoc
-        } else if text.starts_with("//") {
-            CommentFlavor::Line
-        } else {
-            CommentFlavor::Multiline
-        }
-    }
-
-    pub fn is_doc_comment(&self) -> bool {
-        self.flavor().is_doc_comment()
-    }
-
-    pub fn prefix(&self) -> &'static str {
-        self.flavor().prefix()
-    }
-}
-
-#[derive(Debug, PartialEq, Eq)]
-pub enum CommentFlavor {
-    Line,
-    Doc,
-    ModuleDoc,
-    Multiline,
-}
-
-impl CommentFlavor {
-    pub fn prefix(&self) -> &'static str {
-        use self::CommentFlavor::*;
-        match *self {
-            Line => "//",
-            Doc => "///",
-            ModuleDoc => "//!",
-            Multiline => "/*",
-        }
-    }
-
-    pub fn is_doc_comment(&self) -> bool {
-        match self {
-            CommentFlavor::Doc | CommentFlavor::ModuleDoc => true,
-            _ => false,
-        }
-    }
-}
-
-pub struct Whitespace<'a>(SyntaxToken<'a>);
-
-impl<'a> Whitespace<'a> {
-    pub fn cast(token: SyntaxToken<'a>) -> Option<Self> {
-        if token.kind() == WHITESPACE {
-            Some(Whitespace(token))
-        } else {
-            None
-        }
-    }
-
-    pub fn syntax(&self) -> SyntaxToken<'a> {
-        self.0
-    }
-
-    pub fn text(&self) -> &'a SmolStr {
-        self.0.text()
-    }
-
-    pub fn spans_multiple_lines(&self) -> bool {
-        let text = self.text();
-        text.find('\n').map_or(false, |idx| text[idx + 1..].contains('\n'))
-    }
-}
-
 impl Name {
     pub fn text(&self) -> &SmolStr {
         let ident = self.syntax().first_child_or_token().unwrap().as_token().unwrap();
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
new file mode 100644
index 000000000..c830cdccf
--- /dev/null
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -0,0 +1,93 @@
+use crate::{
+    SyntaxToken,
+    SyntaxKind::{COMMENT, WHITESPACE},
+    ast::AstToken,
+};
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub struct Comment<'a>(SyntaxToken<'a>);
+
+impl<'a> AstToken<'a> for Comment<'a> {
+    fn cast(token: SyntaxToken<'a>) -> Option<Self> {
+        if token.kind() == COMMENT {
+            Some(Comment(token))
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> SyntaxToken<'a> {
+        self.0
+    }
+}
+
+impl<'a> Comment<'a> {
+    pub fn flavor(&self) -> CommentFlavor {
+        let text = self.text();
+        if text.starts_with("///") {
+            CommentFlavor::Doc
+        } else if text.starts_with("//!") {
+            CommentFlavor::ModuleDoc
+        } else if text.starts_with("//") {
+            CommentFlavor::Line
+        } else {
+            CommentFlavor::Multiline
+        }
+    }
+
+    pub fn is_doc_comment(&self) -> bool {
+        self.flavor().is_doc_comment()
+    }
+
+    pub fn prefix(&self) -> &'static str {
+        self.flavor().prefix()
+    }
+}
+
+#[derive(Debug, PartialEq, Eq)]
+pub enum CommentFlavor {
+    Line,
+    Doc,
+    ModuleDoc,
+    Multiline,
+}
+
+impl CommentFlavor {
+    pub fn prefix(&self) -> &'static str {
+        use self::CommentFlavor::*;
+        match *self {
+            Line => "//",
+            Doc => "///",
+            ModuleDoc => "//!",
+            Multiline => "/*",
+        }
+    }
+
+    pub fn is_doc_comment(&self) -> bool {
+        match self {
+            CommentFlavor::Doc | CommentFlavor::ModuleDoc => true,
+            _ => false,
+        }
+    }
+}
+
+pub struct Whitespace<'a>(SyntaxToken<'a>);
+
+impl<'a> AstToken<'a> for Whitespace<'a> {
+    fn cast(token: SyntaxToken<'a>) -> Option<Self> {
+        if token.kind() == WHITESPACE {
+            Some(Whitespace(token))
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> SyntaxToken<'a> {
+        self.0
+    }
+}
+
+impl<'a> Whitespace<'a> {
+    pub fn spans_multiple_lines(&self) -> bool {
+        let text = self.text();
+        text.find('\n').map_or(false, |idx| text[idx + 1..].contains('\n'))
+    }
+}
diff --git a/crates/ra_syntax/src/ast/traits.rs b/crates/ra_syntax/src/ast/traits.rs
index 85fe6d5e1..f9021d7bf 100644
--- a/crates/ra_syntax/src/ast/traits.rs
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -2,7 +2,7 @@ use itertools::Itertools;
 
 use crate::{
     syntax_node::{SyntaxNodeChildren, SyntaxElementChildren},
-    ast::{self, child_opt, children, AstNode, AstChildren},
+    ast::{self, child_opt, children, AstNode, AstToken, AstChildren},
 };
 
 pub trait TypeAscriptionOwner: AstNode {