Merge #468

468: decouple ra_editor from other stuff r=matklad a=matklad



Co-authored-by: Aleksey Kladov <[email protected]>

1 files changed, 14 insertions, 1 deletions

diff --git a/crates/ra_syntax/src/algo.rs b/crates/ra_syntax/src/algo.rs
index 13f50d2ef..45747e21d 100644
--- a/crates/ra_syntax/src/algo.rs
+++ b/crates/ra_syntax/src/algo.rs
@@ -2,7 +2,7 @@ pub mod visit;
 
 use rowan::TransparentNewType;
 
-use crate::{SyntaxNode, TextRange, TextUnit};
+use crate::{SyntaxNode, TextRange, TextUnit, AstNode};
 
 pub use rowan::LeafAtOffset;
 
@@ -16,6 +16,19 @@ pub fn find_leaf_at_offset(node: &SyntaxNode, offset: TextUnit) -> LeafAtOffset<
     }
 }
 
+/// Finds a node of specific Ast type at offset. Note that this is slightly
+/// impercise: if the cursor is strictly betwen two nodes of the desired type,
+/// as in
+///
+/// ```no-run
+/// struct Foo {}|struct Bar;
+/// ```
+///
+/// then the left node will be silently prefered.
+pub fn find_node_at_offset<N: AstNode>(syntax: &SyntaxNode, offset: TextUnit) -> Option<&N> {
+    find_leaf_at_offset(syntax, offset).find_map(|leaf| leaf.ancestors().find_map(N::cast))
+}
+
 pub fn find_covering_node(root: &SyntaxNode, range: TextRange) -> &SyntaxNode {
     SyntaxNode::from_repr(root.0.covering_node(range))
 }