1 files changed, 232 insertions, 230 deletions

diff --git a/crates/ra_analysis/src/imp.rs b/crates/ra_analysis/src/imp.rs
index 5ed374c79..eae73c2c4 100644
--- a/crates/ra_analysis/src/imp.rs
+++ b/crates/ra_analysis/src/imp.rs
@@ -1,59 +1,42 @@
-use std::{
-    fmt,
-    sync::Arc,
-};
+use std::sync::Arc;
 
-use rayon::prelude::*;
-use salsa::{Database, ParallelDatabase};
+use salsa::Database;
 
 use hir::{
     self, FnSignatureInfo, Problem, source_binder,
 };
 use ra_db::{FilesDatabase, SourceRoot, SourceRootId, SyntaxDatabase};
-use ra_editor::{self, FileSymbol, find_node_at_offset, LineIndex, LocalEdit, Severity};
+use ra_editor::{self, find_node_at_offset, assists, LocalEdit, Severity};
 use ra_syntax::{
-    algo::find_covering_node,
+    algo::{find_covering_node, visit::{visitor, Visitor}},
     ast::{self, ArgListOwner, Expr, FnDef, NameOwner},
     AstNode, SourceFileNode,
     SyntaxKind::*,
-    SyntaxNodeRef, TextRange, TextUnit,
+    SyntaxNode, SyntaxNodeRef, TextRange, TextUnit,
 };
 
 use crate::{
     AnalysisChange,
-    Cancelable,
-    completion::{CompletionItem, completions},
+    Cancelable, NavigationTarget,
     CrateId, db, Diagnostic, FileId, FilePosition, FileRange, FileSystemEdit,
     Query, ReferenceResolution, RootChange, SourceChange, SourceFileEdit,
-    symbol_index::{LibrarySymbolsQuery, SymbolIndex, SymbolsDatabase},
+    symbol_index::{LibrarySymbolsQuery, FileSymbol},
 };
 
-#[derive(Debug, Default)]
-pub(crate) struct AnalysisHostImpl {
-    db: db::RootDatabase,
-}
-
-impl AnalysisHostImpl {
-    pub fn analysis(&self) -> AnalysisImpl {
-        AnalysisImpl {
-            db: self.db.snapshot(),
-        }
-    }
-    pub fn apply_change(&mut self, change: AnalysisChange) {
+impl db::RootDatabase {
+    pub(crate) fn apply_change(&mut self, change: AnalysisChange) {
         log::info!("apply_change {:?}", change);
         // self.gc_syntax_trees();
         if !change.new_roots.is_empty() {
-            let mut local_roots = Vec::clone(&self.db.local_roots());
+            let mut local_roots = Vec::clone(&self.local_roots());
             for (root_id, is_local) in change.new_roots {
-                self.db
-                    .query_mut(ra_db::SourceRootQuery)
+                self.query_mut(ra_db::SourceRootQuery)
                     .set(root_id, Default::default());
                 if is_local {
                     local_roots.push(root_id);
                 }
             }
-            self.db
-                .query_mut(ra_db::LocalRootsQuery)
+            self.query_mut(ra_db::LocalRootsQuery)
                 .set((), Arc::new(local_roots));
         }
 
@@ -61,53 +44,44 @@ impl AnalysisHostImpl {
             self.apply_root_change(root_id, root_change);
         }
         for (file_id, text) in change.files_changed {
-            self.db.query_mut(ra_db::FileTextQuery).set(file_id, text)
+            self.query_mut(ra_db::FileTextQuery).set(file_id, text)
         }
         if !change.libraries_added.is_empty() {
-            let mut libraries = Vec::clone(&self.db.library_roots());
+            let mut libraries = Vec::clone(&self.library_roots());
             for library in change.libraries_added {
                 libraries.push(library.root_id);
-                self.db
-                    .query_mut(ra_db::SourceRootQuery)
+                self.query_mut(ra_db::SourceRootQuery)
                     .set(library.root_id, Default::default());
-                self.db
-                    .query_mut(LibrarySymbolsQuery)
+                self.query_mut(LibrarySymbolsQuery)
                     .set_constant(library.root_id, Arc::new(library.symbol_index));
                 self.apply_root_change(library.root_id, library.root_change);
             }
-            self.db
-                .query_mut(ra_db::LibraryRootsQuery)
+            self.query_mut(ra_db::LibraryRootsQuery)
                 .set((), Arc::new(libraries));
         }
         if let Some(crate_graph) = change.crate_graph {
-            self.db
-                .query_mut(ra_db::CrateGraphQuery)
+            self.query_mut(ra_db::CrateGraphQuery)
                 .set((), Arc::new(crate_graph))
         }
     }
 
     fn apply_root_change(&mut self, root_id: SourceRootId, root_change: RootChange) {
-        let mut source_root = SourceRoot::clone(&self.db.source_root(root_id));
+        let mut source_root = SourceRoot::clone(&self.source_root(root_id));
         for add_file in root_change.added {
-            self.db
-                .query_mut(ra_db::FileTextQuery)
+            self.query_mut(ra_db::FileTextQuery)
                 .set(add_file.file_id, add_file.text);
-            self.db
-                .query_mut(ra_db::FileRelativePathQuery)
+            self.query_mut(ra_db::FileRelativePathQuery)
                 .set(add_file.file_id, add_file.path.clone());
-            self.db
-                .query_mut(ra_db::FileSourceRootQuery)
+            self.query_mut(ra_db::FileSourceRootQuery)
                 .set(add_file.file_id, root_id);
             source_root.files.insert(add_file.path, add_file.file_id);
         }
         for remove_file in root_change.removed {
-            self.db
-                .query_mut(ra_db::FileTextQuery)
+            self.query_mut(ra_db::FileTextQuery)
                 .set(remove_file.file_id, Default::default());
             source_root.files.remove(&remove_file.path);
         }
-        self.db
-            .query_mut(ra_db::SourceRootQuery)
+        self.query_mut(ra_db::SourceRootQuery)
             .set(root_id, Arc::new(source_root));
     }
 
@@ -116,142 +90,86 @@ impl AnalysisHostImpl {
     /// syntax trees. However, if we actually do that, everything is recomputed
     /// for some reason. Needs investigation.
     fn gc_syntax_trees(&mut self) {
-        self.db
-            .query(ra_db::SourceFileQuery)
+        self.query(ra_db::SourceFileQuery)
             .sweep(salsa::SweepStrategy::default().discard_values());
-        self.db
-            .query(hir::db::SourceFileItemsQuery)
+        self.query(hir::db::SourceFileItemsQuery)
             .sweep(salsa::SweepStrategy::default().discard_values());
-        self.db
-            .query(hir::db::FileItemQuery)
+        self.query(hir::db::FileItemQuery)
             .sweep(salsa::SweepStrategy::default().discard_values());
     }
 }
 
-pub(crate) struct AnalysisImpl {
-    pub(crate) db: salsa::Snapshot<db::RootDatabase>,
-}
-
-impl fmt::Debug for AnalysisImpl {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        let db: &db::RootDatabase = &self.db;
-        fmt.debug_struct("AnalysisImpl").field("db", db).finish()
-    }
-}
-
-impl AnalysisImpl {
-    pub fn file_text(&self, file_id: FileId) -> Arc<String> {
-        self.db.file_text(file_id)
-    }
-    pub fn file_syntax(&self, file_id: FileId) -> SourceFileNode {
-        self.db.source_file(file_id)
-    }
-    pub fn file_line_index(&self, file_id: FileId) -> Arc<LineIndex> {
-        self.db.file_lines(file_id)
-    }
-    pub fn world_symbols(&self, query: Query) -> Cancelable<Vec<(FileId, FileSymbol)>> {
-        /// Need to wrap Snapshot to provide `Clone` impl for `map_with`
-        struct Snap(salsa::Snapshot<db::RootDatabase>);
-        impl Clone for Snap {
-            fn clone(&self) -> Snap {
-                Snap(self.0.snapshot())
-            }
-        }
-
-        let buf: Vec<Arc<SymbolIndex>> = if query.libs {
-            let snap = Snap(self.db.snapshot());
-            self.db
-                .library_roots()
-                .par_iter()
-                .map_with(snap, |db, &lib_id| db.0.library_symbols(lib_id))
-                .collect()
-        } else {
-            let mut files = Vec::new();
-            for &root in self.db.local_roots().iter() {
-                let sr = self.db.source_root(root);
-                files.extend(sr.files.values().map(|&it| it))
-            }
-
-            let snap = Snap(self.db.snapshot());
-            files
-                .par_iter()
-                .map_with(snap, |db, &file_id| db.0.file_symbols(file_id))
-                .filter_map(|it| it.ok())
-                .collect()
-        };
-        Ok(query.search(&buf))
-    }
+impl db::RootDatabase {
     /// This returns `Vec` because a module may be included from several places. We
     /// don't handle this case yet though, so the Vec has length at most one.
-    pub fn parent_module(&self, position: FilePosition) -> Cancelable<Vec<(FileId, FileSymbol)>> {
-        let descr = match source_binder::module_from_position(&*self.db, position)? {
+    pub(crate) fn parent_module(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Vec<NavigationTarget>> {
+        let descr = match source_binder::module_from_position(self, position)? {
             None => return Ok(Vec::new()),
             Some(it) => it,
         };
-        let (file_id, decl) = match descr.parent_link_source(&*self.db) {
+        let (file_id, decl) = match descr.parent_link_source(self) {
             None => return Ok(Vec::new()),
             Some(it) => it,
         };
         let decl = decl.borrowed();
         let decl_name = decl.name().unwrap();
-        let sym = FileSymbol {
+        Ok(vec![NavigationTarget {
+            file_id,
             name: decl_name.text(),
-            node_range: decl_name.syntax().range(),
+            range: decl_name.syntax().range(),
             kind: MODULE,
-        };
-        Ok(vec![(file_id, sym)])
+            ptr: None,
+        }])
     }
     /// Returns `Vec` for the same reason as `parent_module`
-    pub fn crate_for(&self, file_id: FileId) -> Cancelable<Vec<CrateId>> {
-        let descr = match source_binder::module_from_file_id(&*self.db, file_id)? {
+    pub(crate) fn crate_for(&self, file_id: FileId) -> Cancelable<Vec<CrateId>> {
+        let descr = match source_binder::module_from_file_id(self, file_id)? {
             None => return Ok(Vec::new()),
             Some(it) => it,
         };
         let root = descr.crate_root();
-        let file_id = root.source().file_id();
+        let file_id = root.file_id();
 
-        let crate_graph = self.db.crate_graph();
+        let crate_graph = self.crate_graph();
         let crate_id = crate_graph.crate_id_for_crate_root(file_id);
         Ok(crate_id.into_iter().collect())
     }
-    pub fn crate_root(&self, crate_id: CrateId) -> FileId {
-        self.db.crate_graph().crate_root(crate_id)
+    pub(crate) fn crate_root(&self, crate_id: CrateId) -> FileId {
+        self.crate_graph().crate_root(crate_id)
     }
-    pub fn completions(&self, position: FilePosition) -> Cancelable<Option<Vec<CompletionItem>>> {
-        let completions = completions(&self.db, position)?;
-        Ok(completions.map(|it| it.into()))
-    }
-    pub fn approximately_resolve_symbol(
+    pub(crate) fn approximately_resolve_symbol(
         &self,
         position: FilePosition,
     ) -> Cancelable<Option<ReferenceResolution>> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.source_file(position.file_id);
         let syntax = file.syntax();
         if let Some(name_ref) = find_node_at_offset::<ast::NameRef>(syntax, position.offset) {
             let mut rr = ReferenceResolution::new(name_ref.syntax().range());
-            if let Some(fn_descr) = source_binder::function_from_child_node(
-                &*self.db,
-                position.file_id,
-                name_ref.syntax(),
-            )? {
-                let scope = fn_descr.scopes(&*self.db);
+            if let Some(fn_descr) =
+                source_binder::function_from_child_node(self, position.file_id, name_ref.syntax())?
+            {
+                let scope = fn_descr.scopes(self);
                 // First try to resolve the symbol locally
                 if let Some(entry) = scope.resolve_local_name(name_ref) {
-                    rr.add_resolution(
-                        position.file_id,
-                        FileSymbol {
-                            name: entry.name().to_string().into(),
-                            node_range: entry.ptr().range(),
-                            kind: NAME,
-                        },
-                    );
+                    rr.resolves_to.push(NavigationTarget {
+                        file_id: position.file_id,
+                        name: entry.name().to_string().into(),
+                        range: entry.ptr().range(),
+                        kind: NAME,
+                        ptr: None,
+                    });
                     return Ok(Some(rr));
                 };
             }
             // If that fails try the index based approach.
-            for (file_id, symbol) in self.index_resolve(name_ref)? {
-                rr.add_resolution(file_id, symbol);
-            }
+            rr.resolves_to.extend(
+                self.index_resolve(name_ref)?
+                    .into_iter()
+                    .map(NavigationTarget::from_symbol),
+            );
             return Ok(Some(rr));
         }
         if let Some(name) = find_node_at_offset::<ast::Name>(syntax, position.offset) {
@@ -259,19 +177,21 @@ impl AnalysisImpl {
             if let Some(module) = name.syntax().parent().and_then(ast::Module::cast) {
                 if module.has_semi() {
                     if let Some(child_module) =
-                        source_binder::module_from_declaration(&*self.db, position.file_id, module)?
+                        source_binder::module_from_declaration(self, position.file_id, module)?
                     {
-                        let file_id = child_module.source().file_id();
+                        let file_id = child_module.file_id();
                         let name = match child_module.name() {
                             Some(name) => name.to_string().into(),
                             None => "".into(),
                         };
-                        let symbol = FileSymbol {
+                        let symbol = NavigationTarget {
+                            file_id,
                             name,
-                            node_range: TextRange::offset_len(0.into(), 0.into()),
+                            range: TextRange::offset_len(0.into(), 0.into()),
                             kind: MODULE,
+                            ptr: None,
                         };
-                        rr.add_resolution(file_id, symbol);
+                        rr.resolves_to.push(symbol);
                         return Ok(Some(rr));
                     }
                 }
@@ -280,10 +200,13 @@ impl AnalysisImpl {
         Ok(None)
     }
 
-    pub fn find_all_refs(&self, position: FilePosition) -> Cancelable<Vec<(FileId, TextRange)>> {
-        let file = self.db.source_file(position.file_id);
+    pub(crate) fn find_all_refs(
+        &self,
+        position: FilePosition,
+    ) -> Cancelable<Vec<(FileId, TextRange)>> {
+        let file = self.source_file(position.file_id);
         // Find the binding associated with the offset
-        let (binding, descr) = match find_binding(&self.db, &file, position)? {
+        let (binding, descr) = match find_binding(self, &file, position)? {
             None => return Ok(Vec::new()),
             Some(it) => it,
         };
@@ -295,7 +218,7 @@ impl AnalysisImpl {
             .collect::<Vec<_>>();
         ret.extend(
             descr
-                .scopes(&*self.db)
+                .scopes(self)
                 .find_all_refs(binding)
                 .into_iter()
                 .map(|ref_desc| (position.file_id, ref_desc.range)),
@@ -333,9 +256,8 @@ impl AnalysisImpl {
             Ok(Some((binding, descr)))
         }
     }
-    pub fn doc_text_for(&self, file_id: FileId, symbol: FileSymbol) -> Cancelable<Option<String>> {
-        let file = self.db.source_file(file_id);
-        let result = match (symbol.description(&file), symbol.docs(&file)) {
+    pub(crate) fn doc_text_for(&self, nav: NavigationTarget) -> Cancelable<Option<String>> {
+        let result = match (nav.description(self), nav.docs(self)) {
             (Some(desc), Some(docs)) => {
                 Some("```rust\n".to_string() + &*desc + "\n```\n\n" + &*docs)
             }
@@ -347,8 +269,8 @@ impl AnalysisImpl {
         Ok(result)
     }
 
-    pub fn diagnostics(&self, file_id: FileId) -> Cancelable<Vec<Diagnostic>> {
-        let syntax = self.db.source_file(file_id);
+    pub(crate) fn diagnostics(&self, file_id: FileId) -> Cancelable<Vec<Diagnostic>> {
+        let syntax = self.source_file(file_id);
 
         let mut res = ra_editor::diagnostics(&syntax)
             .into_iter()
@@ -359,9 +281,9 @@ impl AnalysisImpl {
                 fix: d.fix.map(|fix| SourceChange::from_local_edit(file_id, fix)),
             })
             .collect::<Vec<_>>();
-        if let Some(m) = source_binder::module_from_file_id(&*self.db, file_id)? {
-            for (name_node, problem) in m.problems(&*self.db) {
-                let source_root = self.db.file_source_root(file_id);
+        if let Some(m) = source_binder::module_from_file_id(self, file_id)? {
+            for (name_node, problem) in m.problems(self) {
+                let source_root = self.file_source_root(file_id);
                 let diag = match problem {
                     Problem::UnresolvedModule { candidate } => {
                         let create_file = FileSystemEdit::CreateFile {
@@ -411,29 +333,19 @@ impl AnalysisImpl {
         Ok(res)
     }
 
-    pub fn assists(&self, frange: FileRange) -> Vec<SourceChange> {
-        let file = self.file_syntax(frange.file_id);
-        let offset = frange.range.start();
-        let actions = vec![
-            ra_editor::flip_comma(&file, offset).map(|f| f()),
-            ra_editor::add_derive(&file, offset).map(|f| f()),
-            ra_editor::add_impl(&file, offset).map(|f| f()),
-            ra_editor::make_pub_crate(&file, offset).map(|f| f()),
-            ra_editor::introduce_variable(&file, frange.range).map(|f| f()),
-        ];
-        actions
+    pub(crate) fn assists(&self, frange: FileRange) -> Vec<SourceChange> {
+        let file = self.source_file(frange.file_id);
+        assists::assists(&file, frange.range)
             .into_iter()
-            .filter_map(|local_edit| {
-                Some(SourceChange::from_local_edit(frange.file_id, local_edit?))
-            })
+            .map(|local_edit| SourceChange::from_local_edit(frange.file_id, local_edit))
             .collect()
     }
 
-    pub fn resolve_callable(
+    pub(crate) fn resolve_callable(
         &self,
         position: FilePosition,
     ) -> Cancelable<Option<(FnSignatureInfo, Option<usize>)>> {
-        let file = self.db.source_file(position.file_id);
+        let file = self.source_file(position.file_id);
         let syntax = file.syntax();
 
         // Find the calling expression and it's NameRef
@@ -442,53 +354,55 @@ impl AnalysisImpl {
 
         // Resolve the function's NameRef (NOTE: this isn't entirely accurate).
         let file_symbols = self.index_resolve(name_ref)?;
-        for (fn_file_id, fs) in file_symbols {
-            if fs.kind == FN_DEF {
-                let fn_file = self.db.source_file(fn_file_id);
-                if let Some(fn_def) = find_node_at_offset(fn_file.syntax(), fs.node_range.start()) {
-                    let descr = ctry!(source_binder::function_from_source(
-                        &*self.db, fn_file_id, fn_def
-                    )?);
-                    if let Some(descriptor) = descr.signature_info(&*self.db) {
-                        // If we have a calling expression let's find which argument we are on
-                        let mut current_parameter = None;
-
-                        let num_params = descriptor.params.len();
-                        let has_self = fn_def.param_list().and_then(|l| l.self_param()).is_some();
-
-                        if num_params == 1 {
-                            if !has_self {
-                                current_parameter = Some(0);
-                            }
-                        } else if num_params > 1 {
-                            // Count how many parameters into the call we are.
-                            // TODO: This is best effort for now and should be fixed at some point.
-                            // It may be better to see where we are in the arg_list and then check
-                            // where offset is in that list (or beyond).
-                            // Revisit this after we get documentation comments in.
-                            if let Some(ref arg_list) = calling_node.arg_list() {
-                                let start = arg_list.syntax().range().start();
-
-                                let range_search = TextRange::from_to(start, position.offset);
-                                let mut commas: usize = arg_list
-                                    .syntax()
-                                    .text()
-                                    .slice(range_search)
-                                    .to_string()
-                                    .matches(',')
-                                    .count();
-
-                                // If we have a method call eat the first param since it's just self.
-                                if has_self {
-                                    commas += 1;
-                                }
-
-                                current_parameter = Some(commas);
-                            }
+        for symbol in file_symbols {
+            if symbol.ptr.kind() == FN_DEF {
+                let fn_file = self.source_file(symbol.file_id);
+                let fn_def = symbol.ptr.resolve(&fn_file);
+                let fn_def = ast::FnDef::cast(fn_def.borrowed()).unwrap();
+                let descr = ctry!(source_binder::function_from_source(
+                    self,
+                    symbol.file_id,
+                    fn_def
+                )?);
+                if let Some(descriptor) = descr.signature_info(self) {
+                    // If we have a calling expression let's find which argument we are on
+                    let mut current_parameter = None;
+
+                    let num_params = descriptor.params.len();
+                    let has_self = fn_def.param_list().and_then(|l| l.self_param()).is_some();
+
+                    if num_params == 1 {
+                        if !has_self {
+                            current_parameter = Some(0);
                         }
+                    } else if num_params > 1 {
+                        // Count how many parameters into the call we are.
+                        // TODO: This is best effort for now and should be fixed at some point.
+                        // It may be better to see where we are in the arg_list and then check
+                        // where offset is in that list (or beyond).
+                        // Revisit this after we get documentation comments in.
+                        if let Some(ref arg_list) = calling_node.arg_list() {
+                            let start = arg_list.syntax().range().start();
+
+                            let range_search = TextRange::from_to(start, position.offset);
+                            let mut commas: usize = arg_list
+                                .syntax()
+                                .text()
+                                .slice(range_search)
+                                .to_string()
+                                .matches(',')
+                                .count();
+
+                            // If we have a method call eat the first param since it's just self.
+                            if has_self {
+                                commas += 1;
+                            }
 
-                        return Ok(Some((descriptor, current_parameter)));
+                            current_parameter = Some(commas);
+                        }
                     }
+
+                    return Ok(Some((descriptor, current_parameter)));
                 }
             }
         }
@@ -496,20 +410,20 @@ impl AnalysisImpl {
         Ok(None)
     }
 
-    pub fn type_of(&self, frange: FileRange) -> Cancelable<Option<String>> {
-        let file = self.db.source_file(frange.file_id);
+    pub(crate) fn type_of(&self, frange: FileRange) -> Cancelable<Option<String>> {
+        let file = self.source_file(frange.file_id);
         let syntax = file.syntax();
         let node = find_covering_node(syntax, frange.range);
         let parent_fn = ctry!(node.ancestors().find_map(FnDef::cast));
         let function = ctry!(source_binder::function_from_source(
-            &*self.db,
+            self,
             frange.file_id,
             parent_fn
         )?);
-        let infer = function.infer(&*self.db)?;
+        let infer = function.infer(self)?;
         Ok(infer.type_of_node(node).map(|t| t.to_string()))
     }
-    pub fn rename(
+    pub(crate) fn rename(
         &self,
         position: FilePosition,
         new_name: &str,
@@ -520,7 +434,7 @@ impl AnalysisImpl {
             .map(|(file_id, text_range)| SourceFileEdit {
                 file_id: *file_id,
                 edit: {
-                    let mut builder = ra_text_edit::TextEditBuilder::new();
+                    let mut builder = ra_text_edit::TextEditBuilder::default();
                     builder.replace(*text_range, new_name.into());
                     builder.finish()
                 },
@@ -528,12 +442,12 @@ impl AnalysisImpl {
             .collect::<Vec<_>>();
         Ok(res)
     }
-    fn index_resolve(&self, name_ref: ast::NameRef) -> Cancelable<Vec<(FileId, FileSymbol)>> {
+    fn index_resolve(&self, name_ref: ast::NameRef) -> Cancelable<Vec<FileSymbol>> {
         let name = name_ref.text();
         let mut query = Query::new(name.to_string());
         query.exact();
         query.limit(4);
-        self.world_symbols(query)
+        crate::symbol_index::world_symbols(self, query)
     }
 }
 
@@ -592,3 +506,91 @@ impl<'a> FnCallNode<'a> {
         }
     }
 }
+
+impl NavigationTarget {
+    fn node(&self, db: &db::RootDatabase) -> Option<SyntaxNode> {
+        let source_file = db.source_file(self.file_id);
+        let source_file = source_file.syntax();
+        let node = source_file
+            .descendants()
+            .find(|node| node.kind() == self.kind && node.range() == self.range)?
+            .owned();
+        Some(node)
+    }
+
+    fn docs(&self, db: &db::RootDatabase) -> Option<String> {
+        let node = self.node(db)?;
+        let node = node.borrowed();
+        fn doc_comments<'a, N: ast::DocCommentsOwner<'a>>(node: N) -> Option<String> {
+            let comments = node.doc_comment_text();
+            if comments.is_empty() {
+                None
+            } else {
+                Some(comments)
+            }
+        }
+
+        visitor()
+            .visit(doc_comments::<ast::FnDef>)
+            .visit(doc_comments::<ast::StructDef>)
+            .visit(doc_comments::<ast::EnumDef>)
+            .visit(doc_comments::<ast::TraitDef>)
+            .visit(doc_comments::<ast::Module>)
+            .visit(doc_comments::<ast::TypeDef>)
+            .visit(doc_comments::<ast::ConstDef>)
+            .visit(doc_comments::<ast::StaticDef>)
+            .accept(node)?
+    }
+
+    /// Get a description of this node.
+    ///
+    /// e.g. `struct Name`, `enum Name`, `fn Name`
+    fn description(&self, db: &db::RootDatabase) -> Option<String> {
+        // TODO: After type inference is done, add type information to improve the output
+        let node = self.node(db)?;
+        let node = node.borrowed();
+        // TODO: Refactor to be have less repetition
+        visitor()
+            .visit(|node: ast::FnDef| {
+                let mut string = "fn ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::StructDef| {
+                let mut string = "struct ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::EnumDef| {
+                let mut string = "enum ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::TraitDef| {
+                let mut string = "trait ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::Module| {
+                let mut string = "mod ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::TypeDef| {
+                let mut string = "type ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::ConstDef| {
+                let mut string = "const ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .visit(|node: ast::StaticDef| {
+                let mut string = "static ".to_string();
+                node.name()?.syntax().text().push_to(&mut string);
+                Some(string)
+            })
+            .accept(node)?
+    }
+}