11 files changed, 292 insertions, 276 deletions

diff --git a/crates/ra_assists/src/add_missing_impl_members.rs b/crates/ra_assists/src/add_missing_impl_members.rs
index 5b01e898e..19a2d05bc 100644
--- a/crates/ra_assists/src/add_missing_impl_members.rs
+++ b/crates/ra_assists/src/add_missing_impl_members.rs
@@ -5,7 +5,7 @@ use crate::{Assist, AssistId, AssistCtx};
 use hir::Resolver;
 use hir::db::HirDatabase;
 use ra_syntax::{SmolStr, SyntaxKind, TextRange, TextUnit, TreeArc};
-use ra_syntax::ast::{self, AstNode, FnDef, ImplItem, ImplItemKind, NameOwner};
+use ra_syntax::ast::{self, AstNode, AstToken, FnDef, ImplItem, ImplItemKind, NameOwner};
 use ra_db::FilePosition;
 use ra_fmt::{leading_indent, reindent};
 
diff --git a/crates/ra_assists/src/inline_local_variable.rs b/crates/ra_assists/src/inline_local_variable.rs
index 0d7b884b8..950c2910b 100644
--- a/crates/ra_assists/src/inline_local_variable.rs
+++ b/crates/ra_assists/src/inline_local_variable.rs
@@ -1,14 +1,9 @@
 use hir::{
     db::HirDatabase,
-    source_binder::function_from_child_node
+    source_binder::function_from_child_node,
 };
 use ra_syntax::{
-    ast::{
-        self,
-        AstNode,
-        PatKind,
-        ExprKind
-    },
+    ast::{self, AstNode, AstToken, PatKind, ExprKind},
     TextRange,
 };
 
diff --git a/crates/ra_fmt/src/lib.rs b/crates/ra_fmt/src/lib.rs
index ea90dc2b8..85b7ce250 100644
--- a/crates/ra_fmt/src/lib.rs
+++ b/crates/ra_fmt/src/lib.rs
@@ -2,9 +2,8 @@
 //!
 use itertools::Itertools;
 use ra_syntax::{
-    AstNode,
     SyntaxNode, SyntaxKind::*, SyntaxToken, SyntaxKind,
-    ast,
+    ast::{self, AstNode, AstToken},
     algo::generate,
 };
 
diff --git a/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap b/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap
index 70ea96e1b..daccd9fba 100644
--- a/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap
+++ b/crates/ra_ide_api/src/completion/snapshots/completion_item__enum_variant_with_details.snap
@@ -1,6 +1,6 @@
 ---
-created: "2019-02-18T09:22:24.062138085Z"
-creator: insta@0.6.2
+created: "2019-04-02T07:43:12.954637543Z"
+creator: insta@0.7.4
 source: crates/ra_ide_api/src/completion/completion_item.rs
 expression: kind_completions
 ---
@@ -33,6 +33,9 @@ expression: kind_completions
         delete: [180; 180),
         insert: "S",
         kind: EnumVariant,
-        detail: "(S)"
+        detail: "(S)",
+        documentation: Documentation(
+            ""
+        )
     }
 ]
diff --git a/crates/ra_ide_api/src/extend_selection.rs b/crates/ra_ide_api/src/extend_selection.rs
index e743bf0fe..7293ba359 100644
--- a/crates/ra_ide_api/src/extend_selection.rs
+++ b/crates/ra_ide_api/src/extend_selection.rs
@@ -1,9 +1,9 @@
 use ra_db::SourceDatabase;
 use ra_syntax::{
-    Direction, SyntaxNode, TextRange, TextUnit, AstNode, SyntaxElement,
+    Direction, SyntaxNode, TextRange, TextUnit, SyntaxElement,
     algo::{find_covering_element, find_token_at_offset, TokenAtOffset},
     SyntaxKind::*, SyntaxToken,
-    ast::Comment,
+    ast::{self, AstNode, AstToken},
 };
 
 use crate::{FileRange, db::RootDatabase};
@@ -55,7 +55,7 @@ fn try_extend_selection(root: &SyntaxNode, range: TextRange) -> Option<TextRange
             if token.range() != range {
                 return Some(token.range());
             }
-            if let Some(comment) = Comment::cast(token) {
+            if let Some(comment) = ast::Comment::cast(token) {
                 if let Some(range) = extend_comments(comment) {
                     return Some(range);
                 }
@@ -176,7 +176,7 @@ fn extend_list_item(node: &SyntaxNode) -> Option<TextRange> {
     None
 }
 
-fn extend_comments(comment: Comment) -> Option<TextRange> {
+fn extend_comments(comment: ast::Comment) -> Option<TextRange> {
     let prev = adj_comments(comment, Direction::Prev);
     let next = adj_comments(comment, Direction::Next);
     if prev != next {
@@ -186,14 +186,14 @@ fn extend_comments(comment: Comment) -> Option<TextRange> {
     }
 }
 
-fn adj_comments(comment: Comment, dir: Direction) -> Comment {
+fn adj_comments(comment: ast::Comment, dir: Direction) -> ast::Comment {
     let mut res = comment;
     for element in comment.syntax().siblings_with_tokens(dir) {
         let token = match element.as_token() {
             None => break,
             Some(token) => token,
         };
-        if let Some(c) = Comment::cast(token) {
+        if let Some(c) = ast::Comment::cast(token) {
             res = c
         } else if token.kind() != WHITESPACE || token.text().contains("\n\n") {
             break;
diff --git a/crates/ra_ide_api/src/folding_ranges.rs b/crates/ra_ide_api/src/folding_ranges.rs
index a6fe8a5d5..eada0b7de 100644
--- a/crates/ra_ide_api/src/folding_ranges.rs
+++ b/crates/ra_ide_api/src/folding_ranges.rs
@@ -1,9 +1,9 @@
 use rustc_hash::FxHashSet;
 
 use ra_syntax::{
-    AstNode, SourceFile, SyntaxNode, TextRange, Direction, SyntaxElement,
+    SourceFile, SyntaxNode, TextRange, Direction, SyntaxElement,
     SyntaxKind::{self, *},
-    ast::{self, VisibilityOwner, Comment},
+    ast::{self, AstNode, AstToken, VisibilityOwner},
 };
 
 #[derive(Debug, PartialEq, Eq)]
@@ -139,8 +139,8 @@ fn contiguous_range_for_group_unless<'a>(
 }
 
 fn contiguous_range_for_comment<'a>(
-    first: Comment<'a>,
-    visited: &mut FxHashSet<Comment<'a>>,
+    first: ast::Comment<'a>,
+    visited: &mut FxHashSet<ast::Comment<'a>>,
 ) -> Option<TextRange> {
     visited.insert(first);
 
@@ -157,7 +157,7 @@ fn contiguous_range_for_comment<'a>(
                         continue;
                     }
                 }
-                if let Some(c) = Comment::cast(token) {
+                if let Some(c) = ast::Comment::cast(token) {
                     if c.flavor() == group_flavor {
                         visited.insert(c);
                         last = c;
diff --git a/crates/ra_ide_api/src/join_lines.rs b/crates/ra_ide_api/src/join_lines.rs
index 57b6f8384..598717311 100644
--- a/crates/ra_ide_api/src/join_lines.rs
+++ b/crates/ra_ide_api/src/join_lines.rs
@@ -1,9 +1,9 @@
 use itertools::Itertools;
 use ra_syntax::{
-    SourceFile, TextRange, TextUnit, AstNode, SyntaxNode, SyntaxElement, SyntaxToken,
+    SourceFile, TextRange, TextUnit, SyntaxNode, SyntaxElement, SyntaxToken,
     SyntaxKind::{self, WHITESPACE, COMMA, R_CURLY, R_PAREN, R_BRACK},
     algo::{find_covering_element, non_trivia_sibling},
-    ast,
+    ast::{self, AstNode, AstToken},
     Direction,
 };
 use ra_fmt::{
diff --git a/crates/ra_ide_api/src/typing.rs b/crates/ra_ide_api/src/typing.rs
index 4510d663d..aeeeea082 100644
--- a/crates/ra_ide_api/src/typing.rs
+++ b/crates/ra_ide_api/src/typing.rs
@@ -2,7 +2,7 @@ use ra_syntax::{
     AstNode, SourceFile, SyntaxKind::*,
     TextUnit, TextRange, SyntaxToken,
     algo::{find_node_at_offset, find_token_at_offset, TokenAtOffset},
-    ast::{self},
+    ast::{self, AstToken},
 };
 use ra_fmt::leading_indent;
 use ra_text_edit::{TextEdit, TextEditBuilder};
diff --git a/crates/ra_syntax/src/ast.rs b/crates/ra_syntax/src/ast.rs
index ffd115cef..beef2c6e2 100644
--- a/crates/ra_syntax/src/ast.rs
+++ b/crates/ra_syntax/src/ast.rs
@@ -1,17 +1,24 @@
 //! Abstract Syntax Tree, layered on top of untyped `SyntaxNode`s
 mod generated;
+mod traits;
+mod tokens;
 
 use std::marker::PhantomData;
 
 use itertools::Itertools;
 
-pub use self::generated::*;
 use crate::{
-    syntax_node::{SyntaxNode, SyntaxNodeChildren, TreeArc, RaTypes, SyntaxToken, SyntaxElement, SyntaxElementChildren},
+    syntax_node::{SyntaxNode, SyntaxNodeChildren, TreeArc, RaTypes, SyntaxToken, SyntaxElement},
     SmolStr,
     SyntaxKind::*,
 };
 
+pub use self::{
+    generated::*,
+    traits::*,
+    tokens::*,
+};
+
 /// The main trait to go from untyped `SyntaxNode`  to a typed ast. The
 /// 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
@@ -25,134 +32,32 @@ pub trait AstNode:
     fn syntax(&self) -> &SyntaxNode;
 }
 
-pub trait TypeAscriptionOwner: AstNode {
-    fn ascribed_type(&self) -> Option<&TypeRef> {
-        child_opt(self)
-    }
-}
-
-pub trait NameOwner: AstNode {
-    fn name(&self) -> Option<&Name> {
-        child_opt(self)
-    }
-}
-
-pub trait VisibilityOwner: AstNode {
-    fn visibility(&self) -> Option<&Visibility> {
-        child_opt(self)
-    }
-}
-
-pub trait LoopBodyOwner: AstNode {
-    fn loop_body(&self) -> Option<&Block> {
-        child_opt(self)
-    }
-}
-
-pub trait ArgListOwner: AstNode {
-    fn arg_list(&self) -> Option<&ArgList> {
-        child_opt(self)
-    }
-}
-
-pub trait FnDefOwner: AstNode {
-    fn functions(&self) -> AstChildren<FnDef> {
-        children(self)
-    }
-}
-
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-pub enum ItemOrMacro<'a> {
-    Item(&'a ModuleItem),
-    Macro(&'a MacroCall),
-}
-
-pub trait ModuleItemOwner: AstNode {
-    fn items(&self) -> AstChildren<ModuleItem> {
-        children(self)
-    }
-    fn items_with_macros(&self) -> ItemOrMacroIter {
-        ItemOrMacroIter(self.syntax().children())
-    }
-}
-
 #[derive(Debug)]
-pub struct ItemOrMacroIter<'a>(SyntaxNodeChildren<'a>);
-
-impl<'a> Iterator for ItemOrMacroIter<'a> {
-    type Item = ItemOrMacro<'a>;
-    fn next(&mut self) -> Option<ItemOrMacro<'a>> {
-        loop {
-            let n = self.0.next()?;
-            if let Some(item) = ModuleItem::cast(n) {
-                return Some(ItemOrMacro::Item(item));
-            }
-            if let Some(call) = MacroCall::cast(n) {
-                return Some(ItemOrMacro::Macro(call));
-            }
-        }
-    }
-}
-
-pub trait TypeParamsOwner: AstNode {
-    fn type_param_list(&self) -> Option<&TypeParamList> {
-        child_opt(self)
-    }
-
-    fn where_clause(&self) -> Option<&WhereClause> {
-        child_opt(self)
-    }
+pub struct AstChildren<'a, N> {
+    inner: SyntaxNodeChildren<'a>,
+    ph: PhantomData<N>,
 }
 
-pub trait TypeBoundsOwner: AstNode {
-    fn type_bound_list(&self) -> Option<&TypeBoundList> {
-        child_opt(self)
+impl<'a, N> AstChildren<'a, N> {
+    fn new(parent: &'a SyntaxNode) -> Self {
+        AstChildren { inner: parent.children(), ph: PhantomData }
     }
 }
 
-pub trait AttrsOwner: AstNode {
-    fn attrs(&self) -> AstChildren<Attr> {
-        children(self)
-    }
-    fn has_atom_attr(&self, atom: &str) -> bool {
-        self.attrs().filter_map(|x| x.as_atom()).any(|x| x == atom)
+impl<'a, N: AstNode + 'a> Iterator for AstChildren<'a, N> {
+    type Item = &'a N;
+    fn next(&mut self) -> Option<&'a N> {
+        self.inner.by_ref().find_map(N::cast)
     }
 }
 
-pub trait DocCommentsOwner: AstNode {
-    fn doc_comments(&self) -> CommentIter {
-        CommentIter { iter: self.syntax().children_with_tokens() }
-    }
-
-    /// Returns the textual content of a doc comment block as a single string.
-    /// That is, strips leading `///` (+ optional 1 character of whitespace)
-    /// and joins lines.
-    fn doc_comment_text(&self) -> Option<std::string::String> {
-        let docs = self
-            .doc_comments()
-            .filter(|comment| comment.is_doc_comment())
-            .map(|comment| {
-                let prefix_len = comment.prefix().len();
-
-                let line = comment.text().as_str();
-
-                // Determine if the prefix or prefix + 1 char is stripped
-                let pos =
-                    if line.chars().nth(prefix_len).map(|c| c.is_whitespace()).unwrap_or(false) {
-                        prefix_len + 1
-                    } else {
-                        prefix_len
-                    };
-
-                line[pos..].to_owned()
-            })
-            .join("\n");
-
-        if docs.is_empty() {
-            None
-        } else {
-            Some(docs)
-        }
+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()
     }
 }
 
@@ -203,111 +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()
-    }
-}
-
-pub struct CommentIter<'a> {
-    iter: SyntaxElementChildren<'a>,
-}
-
-impl<'a> Iterator for CommentIter<'a> {
-    type Item = Comment<'a>;
-    fn next(&mut self) -> Option<Comment<'a>> {
-        self.iter.by_ref().find_map(|el| el.as_token().and_then(Comment::cast))
-    }
-}
-
-#[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();
@@ -468,29 +268,6 @@ fn children<P: AstNode, C: AstNode>(parent: &P) -> AstChildren<C> {
     AstChildren::new(parent.syntax())
 }
 
-#[derive(Debug)]
-pub struct AstChildren<'a, N> {
-    inner: SyntaxNodeChildren<'a>,
-    ph: PhantomData<N>,
-}
-
-impl<'a, N> AstChildren<'a, N> {
-    fn new(parent: &'a SyntaxNode) -> Self {
-        AstChildren { inner: parent.children(), ph: PhantomData }
-    }
-}
-
-impl<'a, N: AstNode + 'a> Iterator for AstChildren<'a, N> {
-    type Item = &'a N;
-    fn next(&mut self) -> Option<&'a N> {
-        loop {
-            if let Some(n) = N::cast(self.inner.next()?) {
-                return Some(n);
-            }
-        }
-    }
-}
-
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub enum StructFlavor<'a> {
     Tuple(&'a PosFieldDefList),
diff --git a/crates/ra_syntax/src/ast/tokens.rs b/crates/ra_syntax/src/ast/tokens.rs
new file mode 100644
index 000000000..76a12cd64
--- /dev/null
+++ b/crates/ra_syntax/src/ast/tokens.rs
@@ -0,0 +1,92 @@
+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::OuterDoc
+        } else if text.starts_with("//!") {
+            CommentFlavor::InnerDoc
+        } 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,
+    OuterDoc,
+    InnerDoc,
+    Multiline,
+}
+
+impl CommentFlavor {
+    pub fn prefix(&self) -> &'static str {
+        match *self {
+            CommentFlavor::Line => "//",
+            CommentFlavor::OuterDoc => "///",
+            CommentFlavor::InnerDoc => "//!",
+            CommentFlavor::Multiline => "/*",
+        }
+    }
+
+    pub fn is_doc_comment(&self) -> bool {
+        match self {
+            CommentFlavor::OuterDoc | CommentFlavor::InnerDoc => 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
new file mode 100644
index 000000000..43d1509fa
--- /dev/null
+++ b/crates/ra_syntax/src/ast/traits.rs
@@ -0,0 +1,150 @@
+use itertools::Itertools;
+
+use crate::{
+    syntax_node::{SyntaxNodeChildren, SyntaxElementChildren},
+    ast::{self, child_opt, children, AstNode, AstToken, AstChildren},
+};
+
+pub trait TypeAscriptionOwner: AstNode {
+    fn ascribed_type(&self) -> Option<&ast::TypeRef> {
+        child_opt(self)
+    }
+}
+
+pub trait NameOwner: AstNode {
+    fn name(&self) -> Option<&ast::Name> {
+        child_opt(self)
+    }
+}
+
+pub trait VisibilityOwner: AstNode {
+    fn visibility(&self) -> Option<&ast::Visibility> {
+        child_opt(self)
+    }
+}
+
+pub trait LoopBodyOwner: AstNode {
+    fn loop_body(&self) -> Option<&ast::Block> {
+        child_opt(self)
+    }
+}
+
+pub trait ArgListOwner: AstNode {
+    fn arg_list(&self) -> Option<&ast::ArgList> {
+        child_opt(self)
+    }
+}
+
+pub trait FnDefOwner: AstNode {
+    fn functions(&self) -> AstChildren<ast::FnDef> {
+        children(self)
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ItemOrMacro<'a> {
+    Item(&'a ast::ModuleItem),
+    Macro(&'a ast::MacroCall),
+}
+
+pub trait ModuleItemOwner: AstNode {
+    fn items(&self) -> AstChildren<ast::ModuleItem> {
+        children(self)
+    }
+    fn items_with_macros(&self) -> ItemOrMacroIter {
+        ItemOrMacroIter(self.syntax().children())
+    }
+}
+
+#[derive(Debug)]
+pub struct ItemOrMacroIter<'a>(SyntaxNodeChildren<'a>);
+
+impl<'a> Iterator for ItemOrMacroIter<'a> {
+    type Item = ItemOrMacro<'a>;
+    fn next(&mut self) -> Option<ItemOrMacro<'a>> {
+        loop {
+            let n = self.0.next()?;
+            if let Some(item) = ast::ModuleItem::cast(n) {
+                return Some(ItemOrMacro::Item(item));
+            }
+            if let Some(call) = ast::MacroCall::cast(n) {
+                return Some(ItemOrMacro::Macro(call));
+            }
+        }
+    }
+}
+
+pub trait TypeParamsOwner: AstNode {
+    fn type_param_list(&self) -> Option<&ast::TypeParamList> {
+        child_opt(self)
+    }
+
+    fn where_clause(&self) -> Option<&ast::WhereClause> {
+        child_opt(self)
+    }
+}
+
+pub trait TypeBoundsOwner: AstNode {
+    fn type_bound_list(&self) -> Option<&ast::TypeBoundList> {
+        child_opt(self)
+    }
+}
+
+pub trait AttrsOwner: AstNode {
+    fn attrs(&self) -> AstChildren<ast::Attr> {
+        children(self)
+    }
+    fn has_atom_attr(&self, atom: &str) -> bool {
+        self.attrs().filter_map(|x| x.as_atom()).any(|x| x == atom)
+    }
+}
+
+pub trait DocCommentsOwner: AstNode {
+    fn doc_comments(&self) -> CommentIter {
+        CommentIter { iter: self.syntax().children_with_tokens() }
+    }
+
+    /// Returns the textual content of a doc comment block as a single string.
+    /// That is, strips leading `///` (+ optional 1 character of whitespace)
+    /// and joins lines.
+    fn doc_comment_text(&self) -> Option<String> {
+        let mut has_comments = false;
+        let docs = self
+            .doc_comments()
+            .filter(|comment| comment.is_doc_comment())
+            .map(|comment| {
+                has_comments = true;
+                let prefix_len = comment.prefix().len();
+
+                let line = comment.text().as_str();
+
+                // Determine if the prefix or prefix + 1 char is stripped
+                let pos =
+                    if line.chars().nth(prefix_len).map(|c| c.is_whitespace()).unwrap_or(false) {
+                        prefix_len + 1
+                    } else {
+                        prefix_len
+                    };
+
+                line[pos..].to_owned()
+            })
+            .join("\n");
+
+        if has_comments {
+            Some(docs)
+        } else {
+            None
+        }
+    }
+}
+
+pub struct CommentIter<'a> {
+    iter: SyntaxElementChildren<'a>,
+}
+
+impl<'a> Iterator for CommentIter<'a> {
+    type Item = ast::Comment<'a>;
+    fn next(&mut self) -> Option<ast::Comment<'a>> {
+        self.iter.by_ref().find_map(|el| el.as_token().and_then(ast::Comment::cast))
+    }
+}