Initial support for lang items.

crates/ra_syntax/src/ast/extensions.rs

@@ -65,6 +65,20 @@ impl ast::Attr {
             None
         }
     }
+
+    pub fn as_key_value(&self) -> Option<(SmolStr, SmolStr)> {
+        let tt = self.value()?;
+        let tt_node = tt.syntax();
+        let attr = tt_node.children_with_tokens().nth(1)?;
+        if attr.kind() == IDENT {
+            let key = attr.as_token()?.text().clone();
+            let val_node = tt_node.children_with_tokens().find(|t| t.kind() == STRING)?;
+            let val = val_node.as_token()?.text().trim_start_matches("\"").trim_end_matches("\"");
+            Some((key, SmolStr::new(val)))
+        } else {
+            None
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]

crates/ra_syntax/src/ast/generated.rs

@@ -1325,6 +1325,7 @@ impl ToOwned for ImplBlock {
 
 
 impl ast::TypeParamsOwner for ImplBlock {}
+impl ast::AttrsOwner for ImplBlock {}
 impl ImplBlock {
     pub fn item_list(&self) -> Option<&ItemList> {
         super::child_opt(self)

crates/ra_syntax/src/grammar.ron

@@ -341,7 +341,7 @@ Grammar(
             ],
             options: ["TypeRef"]
         ),
-        "ImplBlock": (options: ["ItemList"], traits: ["TypeParamsOwner"]),
+        "ImplBlock": (options: ["ItemList"], traits: ["TypeParamsOwner", "AttrsOwner"]),
 
         "ParenType": (options: ["TypeRef"]),
         "TupleType": ( collections: [["fields", "TypeRef"]] ),