Scale back to only two traits

crates/ra_syntax/src/ast.rs

@@ -64,6 +64,22 @@ pub trait AstToken {
     }
 }
 
+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> {

crates/ra_syntax/src/ast/extensions.rs

@@ -5,8 +5,7 @@ use itertools::Itertools;
 
 use crate::{
     ast::{
-        self, child_opt, child_token_opt, children, AstElement, AstNode, AstToken, AttrInput,
-        NameOwner, SyntaxNode,
+        self, child_opt, children, support, AstNode, AstToken, AttrInput, NameOwner, SyntaxNode,
     },
     SmolStr, SyntaxElement,
     SyntaxKind::*,
@@ -437,7 +436,7 @@ impl ast::TypeBound {
                 .skip_while(|it| it.kind() != T![const])
                 .find_map(ast::Question::cast)
         } else {
-            child_token_opt(self)
+            support::token(&self.syntax)
         }
     }
 }
@@ -509,7 +508,7 @@ impl ast::RangePat {
     pub fn start(&self) -> Option<ast::Pat> {
         self.syntax()
             .children_with_tokens()
-            .take_while(|it| !ast::RangeSeparator::can_cast_element(it.kind()))
+            .take_while(|it| !ast::RangeSeparator::can_cast(it.kind()))
             .filter_map(|it| it.into_node())
             .find_map(ast::Pat::cast)
     }
@@ -517,7 +516,7 @@ impl ast::RangePat {
     pub fn end(&self) -> Option<ast::Pat> {
         self.syntax()
             .children_with_tokens()
-            .skip_while(|it| !ast::RangeSeparator::can_cast_element(it.kind()))
+            .skip_while(|it| !ast::RangeSeparator::can_cast(it.kind()))
             .filter_map(|it| it.into_node())
             .find_map(ast::Pat::cast)
     }
@@ -525,10 +524,10 @@ impl ast::RangePat {
 
 impl ast::TokenTree {
     pub fn left_delimiter(&self) -> Option<ast::LeftDelimiter> {
-        self.syntax().first_child_or_token().and_then(ast::LeftDelimiter::cast_element)
+        self.syntax().first_child_or_token()?.into_token().and_then(ast::LeftDelimiter::cast)
     }
 
     pub fn right_delimiter(&self) -> Option<ast::RightDelimiter> {
-        self.syntax().last_child_or_token().and_then(ast::RightDelimiter::cast_element)
+        self.syntax().last_child_or_token()?.into_token().and_then(ast::RightDelimiter::cast)
     }
 }

crates/ra_syntax/src/ast/traits.rs

@@ -4,9 +4,9 @@
 
 use itertools::Itertools;
 
-use crate::ast::{
-    self, child_elements, child_opt, child_token_opt, child_tokens, children, AstChildElements,
-    AstChildTokens, AstChildren, AstNode, AstToken,
+use crate::{
+    ast::{self, child_opt, children, support, AstChildren, AstNode, AstToken},
+    syntax_node::SyntaxElementChildren,
 };
 
 pub trait TypeAscriptionOwner: AstNode {
@@ -71,7 +71,7 @@ pub trait TypeBoundsOwner: AstNode {
     }
 
     fn colon(&self) -> Option<ast::Colon> {
-        child_token_opt(self)
+        support::token(self.syntax())
     }
 }
 
@@ -82,14 +82,11 @@ pub trait AttrsOwner: AstNode {
     fn has_atom_attr(&self, atom: &str) -> bool {
         self.attrs().filter_map(|x| x.as_simple_atom()).any(|x| x == atom)
     }
-    fn attr_or_comments(&self) -> AstChildElements<ast::AttrOrComment> {
-        child_elements(self)
-    }
 }
 
 pub trait DocCommentsOwner: AstNode {
-    fn doc_comments(&self) -> AstChildTokens<ast::Comment> {
-        child_tokens(self)
+    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.
@@ -134,3 +131,14 @@ pub trait DocCommentsOwner: AstNode {
         }
     }
 }
+
+pub struct CommentIter {
+    iter: SyntaxElementChildren,
+}
+
+impl Iterator for CommentIter {
+    type Item = ast::Comment;
+    fn next(&mut self) -> Option<ast::Comment> {
+        self.iter.by_ref().find_map(|el| el.into_token().and_then(ast::Comment::cast))
+    }
+}