9 files changed, 246 insertions, 182 deletions

diff --git a/code/src/extension.ts b/code/src/extension.ts
index 95305db2d..084a9d769 100644
--- a/code/src/extension.ts
+++ b/code/src/extension.ts
@@ -60,14 +60,18 @@ export function activate(context: vscode.ExtensionContext) {
     vscode.workspace.onDidChangeTextDocument((event: vscode.TextDocumentChangeEvent) => {
         let doc = event.document
         if (doc.languageId != "rust") return
-        // We need to order this after LS updates, but there's no API for that.
-        // Hence, good old setTimeout.
-        setTimeout(() => {
+        afterLs(() => {
             textDocumentContentProvider.eventEmitter.fire(uris.syntaxTree)
-        }, 10)
+        })
     }, null, context.subscriptions)
 }
 
+// We need to order this after LS updates, but there's no API for that.
+// Hence, good old setTimeout.
+function afterLs(f) {
+    setTimeout(f, 10)
+}
+
 export function deactivate(): Thenable<void> {
     if (!client) {
         return undefined;
@@ -118,7 +122,9 @@ function startServer() {
                 if (editor == null) return
                 if (!editor.selection.isEmpty) return
                 let position = client.protocol2CodeConverter.asPosition(params)
-                editor.selection = new vscode.Selection(position, position);
+                afterLs(() => {
+                    editor.selection = new vscode.Selection(position, position)
+                })
             }
         )
     })
diff --git a/crates/libanalysis/src/lib.rs b/crates/libanalysis/src/lib.rs
index a50a0f32f..b1093fe83 100644
--- a/crates/libanalysis/src/lib.rs
+++ b/crates/libanalysis/src/lib.rs
@@ -40,6 +40,7 @@ const INDEXING_THRESHOLD: usize = 128;
 
 pub type FileResolver = dyn Fn(FileId, &Path) -> Option<FileId> + Send + Sync;
 
+#[derive(Debug)]
 pub struct WorldState {
     data: Arc<WorldData>
 }
diff --git a/crates/libeditor/src/code_actions.rs b/crates/libeditor/src/code_actions.rs
index 6df64be12..4b2515835 100644
--- a/crates/libeditor/src/code_actions.rs
+++ b/crates/libeditor/src/code_actions.rs
@@ -71,13 +71,11 @@ fn non_trivia_sibling(node: SyntaxNodeRef, direction: Direction) -> Option<Synta
         .find(|node| !node.kind().is_trivia())
 }
 
-fn find_non_trivia_leaf(syntax: SyntaxNodeRef, offset: TextUnit) -> Option<SyntaxNodeRef> {
-    find_leaf_at_offset(syntax, offset)
-        .find(|leaf| !leaf.kind().is_trivia())
-}
-
 pub fn find_node<'a, N: AstNode<&'a SyntaxRoot>>(syntax: SyntaxNodeRef<'a>, offset: TextUnit) -> Option<N> {
-    let leaf = find_non_trivia_leaf(syntax, offset)?;
+    let leaves = find_leaf_at_offset(syntax, offset);
+    let leaf = leaves.clone()
+        .find(|leaf| !leaf.kind().is_trivia())
+        .or_else(|| leaves.right_biased())?;
     ancestors(leaf)
         .filter_map(N::cast)
         .next()
diff --git a/crates/libeditor/tests/test.rs b/crates/libeditor/tests/test.rs
index df4cb65d1..cc4226710 100644
--- a/crates/libeditor/tests/test.rs
+++ b/crates/libeditor/tests/test.rs
@@ -1,11 +1,8 @@
 extern crate libeditor;
 extern crate libsyntax2;
-extern crate itertools;
 #[macro_use]
 extern crate assert_eq_text;
 
-use std::fmt;
-use itertools::Itertools;
 use assert_eq_text::{assert_eq_dbg};
 use libeditor::{
     File, TextUnit, TextRange, ActionResult, CursorPosition,
@@ -119,6 +116,11 @@ fn test_add_derive() {
         |file, off| add_derive(file, off).map(|f| f()),
     );
     check_action(
+        "struct Foo { <|> a: i32, }",
+        "#[derive(<|>)]\nstruct Foo {  a: i32, }",
+        |file, off| add_derive(file, off).map(|f| f()),
+    );
+    check_action(
         "#[derive(Clone)]\nstruct Foo { a: i32<|>, }",
         "#[derive(Clone<|>)]\nstruct Foo { a: i32, }",
         |file, off| add_derive(file, off).map(|f| f()),
diff --git a/crates/server/src/conv.rs b/crates/server/src/conv.rs
index b3709ccaf..fc9056914 100644
--- a/crates/server/src/conv.rs
+++ b/crates/server/src/conv.rs
@@ -6,7 +6,10 @@ use libeditor::{LineIndex, LineCol, Edit, AtomEdit};
 use libsyntax2::{SyntaxKind, TextUnit, TextRange};
 use libanalysis::FileId;
 
-use {Result, PathMap};
+use {
+    Result,
+    server_world::ServerWorld,
+};
 
 pub trait Conv {
     type Output;
@@ -126,57 +129,52 @@ impl<T: ConvWith> ConvWith for Option<T> {
 }
 
 impl<'a> TryConvWith for &'a Url {
-    type Ctx = PathMap;
+    type Ctx = ServerWorld;
     type Output = FileId;
-    fn try_conv_with(self, path_map: &PathMap) -> Result<FileId> {
-        let path = self.to_file_path()
-            .map_err(|()| format_err!("invalid uri: {}", self))?;
-        path_map.get_id(&path).ok_or_else(|| format_err!("unknown file: {}", path.display()))
+    fn try_conv_with(self, world: &ServerWorld) -> Result<FileId> {
+        world.uri_to_file_id(self)
     }
 }
 
 impl TryConvWith for FileId {
-    type Ctx = PathMap;
+    type Ctx = ServerWorld;
     type Output = Url;
-    fn try_conv_with(self, path_map: &PathMap) -> Result<Url> {
-        let path = path_map.get_path(self);
-        let url = Url::from_file_path(path)
-            .map_err(|()| format_err!("can't convert path to url: {}", path.display()))?;
-        Ok(url)
+    fn try_conv_with(self, world: &ServerWorld) -> Result<Url> {
+        world.file_id_to_uri(self)
     }
 }
 
 impl<'a> TryConvWith for &'a TextDocumentItem {
-    type Ctx = PathMap;
+    type Ctx = ServerWorld;
     type Output = FileId;
-    fn try_conv_with(self, path_map: &PathMap) -> Result<FileId> {
-        self.uri.try_conv_with(path_map)
+    fn try_conv_with(self, world: &ServerWorld) -> Result<FileId> {
+        self.uri.try_conv_with(world)
     }
 }
 
 impl<'a> TryConvWith for &'a VersionedTextDocumentIdentifier {
-    type Ctx = PathMap;
+    type Ctx = ServerWorld;
     type Output = FileId;
-    fn try_conv_with(self, path_map: &PathMap) -> Result<FileId> {
-        self.uri.try_conv_with(path_map)
+    fn try_conv_with(self, world: &ServerWorld) -> Result<FileId> {
+        self.uri.try_conv_with(world)
     }
 }
 
 impl<'a> TryConvWith for &'a TextDocumentIdentifier {
-    type Ctx = PathMap;
+    type Ctx = ServerWorld;
     type Output = FileId;
-    fn try_conv_with(self, path_map: &PathMap) -> Result<FileId> {
-        self.uri.try_conv_with(path_map)
+    fn try_conv_with(self, world: &ServerWorld) -> Result<FileId> {
+        world.uri_to_file_id(&self.uri)
     }
 }
 
 pub fn to_location(
     file_id: FileId,
     range: TextRange,
-    path_map: &PathMap,
+    world: &ServerWorld,
     line_index: &LineIndex,
 ) -> Result<Location> {
-        let url = file_id.try_conv_with(path_map)?;
+        let url = file_id.try_conv_with(world)?;
         let loc = Location::new(
             url,
             range.conv_with(line_index),
diff --git a/crates/server/src/main.rs b/crates/server/src/main.rs
index 71d53199c..5e4c0fe7e 100644
--- a/crates/server/src/main.rs
+++ b/crates/server/src/main.rs
@@ -27,15 +27,14 @@ mod conv;
 mod main_loop;
 mod vfs;
 mod path_map;
+mod server_world;
 
 use threadpool::ThreadPool;
 use crossbeam_channel::bounded;
 use flexi_logger::{Logger, Duplicate};
-use libanalysis::WorldState;
 
 use ::{
     io::{Io, RawMsg, RawResponse, RawRequest, RawNotification},
-    path_map::PathMap,
 };
 
 pub type Result<T> = ::std::result::Result<T, ::failure::Error>;
@@ -116,7 +115,6 @@ enum Task {
 
 fn initialized(io: &mut Io) -> Result<()> {
     {
-        let mut world = WorldState::new();
         let mut pool = ThreadPool::new(4);
         let (task_sender, task_receiver) = bounded::<Task>(16);
         let (fs_events_receiver, watcher) = vfs::watch(vec![
@@ -125,7 +123,6 @@ fn initialized(io: &mut Io) -> Result<()> {
         info!("lifecycle: handshake finished, server ready to serve requests");
         let res = main_loop::main_loop(
             io,
-            &mut world,
             &mut pool,
             task_sender,
             task_receiver.clone(),
diff --git a/crates/server/src/main_loop/handlers.rs b/crates/server/src/main_loop/handlers.rs
index f25c64c97..675f69bec 100644
--- a/crates/server/src/main_loop/handlers.rs
+++ b/crates/server/src/main_loop/handlers.rs
@@ -5,35 +5,33 @@ use languageserver_types::{
     Command, TextDocumentIdentifier, WorkspaceEdit,
     SymbolInformation, Position,
 };
-use libanalysis::{World, Query};
+use libanalysis::{Query};
 use libeditor::{self, CursorPosition};
 use libsyntax2::TextUnit;
 use serde_json::{to_value, from_value};
 
 use ::{
-    PathMap,
     req::{self, Decoration}, Result,
     conv::{Conv, ConvWith, TryConvWith, MapConvWith, to_location},
+    server_world::ServerWorld,
 };
 
 pub fn handle_syntax_tree(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::SyntaxTreeParams,
 ) -> Result<String> {
-    let id = params.text_document.try_conv_with(&path_map)?;
-    let file = world.file_syntax(id)?;
+    let id = params.text_document.try_conv_with(&world)?;
+    let file = world.analysis().file_syntax(id)?;
     Ok(libeditor::syntax_tree(&file))
 }
 
 pub fn handle_extend_selection(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::ExtendSelectionParams,
 ) -> Result<req::ExtendSelectionResult> {
-    let file_id = params.text_document.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = params.text_document.try_conv_with(&world)?;
+    let file = world.analysis().file_syntax(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let selections = params.selections.into_iter()
         .map_conv_with(&line_index)
         .map(|r| libeditor::extend_selection(&file, r).unwrap_or(r))
@@ -43,13 +41,12 @@ pub fn handle_extend_selection(
 }
 
 pub fn handle_find_matching_brace(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::FindMatchingBraceParams,
 ) -> Result<Vec<Position>> {
-    let file_id = params.text_document.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = params.text_document.try_conv_with(&world)?;
+    let file = world.analysis().file_syntax(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let res = params.offsets
         .into_iter()
         .map_conv_with(&line_index)
@@ -62,13 +59,12 @@ pub fn handle_find_matching_brace(
 }
 
 pub fn handle_document_symbol(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::DocumentSymbolParams,
 ) -> Result<Option<req::DocumentSymbolResponse>> {
-    let file_id = params.text_document.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = params.text_document.try_conv_with(&world)?;
+    let file = world.analysis().file_syntax(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
 
     let mut parents: Vec<(DocumentSymbol, Option<usize>)> = Vec::new();
 
@@ -102,13 +98,12 @@ pub fn handle_document_symbol(
 }
 
 pub fn handle_code_action(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::CodeActionParams,
 ) -> Result<Option<Vec<Command>>> {
-    let file_id = params.text_document.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = params.text_document.try_conv_with(&world)?;
+    let file = world.analysis().file_syntax(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let offset = params.range.conv_with(&line_index).start();
     let mut ret = Vec::new();
 
@@ -127,8 +122,7 @@ pub fn handle_code_action(
 }
 
 pub fn handle_workspace_symbol(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::WorkspaceSymbolParams,
 ) -> Result<Option<Vec<SymbolInformation>>> {
     let all_symbols = params.query.contains("#");
@@ -143,25 +137,25 @@ pub fn handle_workspace_symbol(
         q.limit(128);
         q
     };
-    let mut res = exec_query(&world, &path_map, query)?;
+    let mut res = exec_query(&world, query)?;
     if res.is_empty() && !all_symbols {
         let mut query = Query::new(params.query);
         query.limit(128);
-        res = exec_query(&world, &path_map, query)?;
+        res = exec_query(&world, query)?;
     }
 
     return Ok(Some(res));
 
-    fn exec_query(world: &World, path_map: &PathMap, query: Query) -> Result<Vec<SymbolInformation>> {
+    fn exec_query(world: &ServerWorld, query: Query) -> Result<Vec<SymbolInformation>> {
         let mut res = Vec::new();
-        for (file_id, symbol) in world.world_symbols(query) {
-            let line_index = world.file_line_index(file_id)?;
+        for (file_id, symbol) in world.analysis().world_symbols(query) {
+            let line_index = world.analysis().file_line_index(file_id)?;
             let info = SymbolInformation {
                 name: symbol.name.to_string(),
                 kind: symbol.kind.conv(),
                 location: to_location(
                     file_id, symbol.node_range,
-                    path_map, &line_index
+                    world, &line_index
                 )?,
                 container_name: None,
             };
@@ -172,19 +166,18 @@ pub fn handle_workspace_symbol(
 }
 
 pub fn handle_goto_definition(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     params: req::TextDocumentPositionParams,
 ) -> Result<Option<req::GotoDefinitionResponse>> {
-    let file_id = params.text_document.try_conv_with(&path_map)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = params.text_document.try_conv_with(&world)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let offset = params.position.conv_with(&line_index);
     let mut res = Vec::new();
-    for (file_id, symbol) in world.approximately_resolve_symbol(file_id, offset)? {
-        let line_index = world.file_line_index(file_id)?;
+    for (file_id, symbol) in world.analysis().approximately_resolve_symbol(file_id, offset)? {
+        let line_index = world.analysis().file_line_index(file_id)?;
         let location = to_location(
             file_id, symbol.node_range,
-            &path_map, &line_index,
+            &world, &line_index,
         )?;
         res.push(location)
     }
@@ -192,8 +185,7 @@ pub fn handle_goto_definition(
 }
 
 pub fn handle_execute_command(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     mut params: req::ExecuteCommandParams,
 ) -> Result<(req::ApplyWorkspaceEditParams, Option<Position>)> {
     if params.command.as_str() != "apply_code_action" {
@@ -204,13 +196,13 @@ pub fn handle_execute_command(
     }
     let arg = params.arguments.pop().unwrap();
     let arg: ActionRequest = from_value(arg)?;
-    let file_id = arg.text_document.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
+    let file_id = arg.text_document.try_conv_with(&world)?;
+    let file = world.analysis().file_syntax(file_id)?;
     let action_result = match arg.id {
         ActionId::FlipComma => libeditor::flip_comma(&file, arg.offset).map(|f| f()),
         ActionId::AddDerive => libeditor::add_derive(&file, arg.offset).map(|f| f()),
     }.ok_or_else(|| format_err!("command not applicable"))?;
-    let line_index = world.file_line_index(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let mut changes = HashMap::new();
     changes.insert(
         arg.text_document.uri,
@@ -265,13 +257,12 @@ impl ActionId {
 }
 
 pub fn publish_diagnostics(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     uri: Url
 ) -> Result<req::PublishDiagnosticsParams> {
-    let file_id = uri.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = world.uri_to_file_id(&uri)?;
+    let file = world.analysis().file_syntax(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let diagnostics = libeditor::diagnostics(&file)
         .into_iter()
         .map(|d| Diagnostic {
@@ -286,13 +277,12 @@ pub fn publish_diagnostics(
 }
 
 pub fn publish_decorations(
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     uri: Url
 ) -> Result<req::PublishDecorationsParams> {
-    let file_id = uri.try_conv_with(&path_map)?;
-    let file = world.file_syntax(file_id)?;
-    let line_index = world.file_line_index(file_id)?;
+    let file_id = world.uri_to_file_id(&uri)?;
+    let file = world.analysis().file_syntax(file_id)?;
+    let line_index = world.analysis().file_line_index(file_id)?;
     let decorations = libeditor::highlight(&file)
         .into_iter()
         .map(|h| Decoration {
diff --git a/crates/server/src/main_loop/mod.rs b/crates/server/src/main_loop/mod.rs
index a8340df59..ad7c480dc 100644
--- a/crates/server/src/main_loop/mod.rs
+++ b/crates/server/src/main_loop/mod.rs
@@ -1,21 +1,20 @@
 mod handlers;
 
 use std::{
-    collections::{HashSet, HashMap},
+    collections::{HashSet},
 };
 
 use threadpool::ThreadPool;
 use crossbeam_channel::{Sender, Receiver};
 use languageserver_types::Url;
-use libanalysis::{World, WorldState, FileId};
 use serde_json::to_value;
 
 use {
     req, dispatch,
-    Task, Result, PathMap,
+    Task, Result,
     io::{Io, RawMsg, RawRequest, RawNotification},
-    vfs::{FileEvent, FileEventKind},
-    conv::TryConvWith,
+    vfs::FileEvent,
+    server_world::{ServerWorldState, ServerWorld},
     main_loop::handlers::{
         handle_syntax_tree,
         handle_extend_selection,
@@ -32,17 +31,16 @@ use {
 
 pub(super) fn main_loop(
     io: &mut Io,
-    world: &mut WorldState,
     pool: &mut ThreadPool,
     task_sender: Sender<Task>,
     task_receiver: Receiver<Task>,
     fs_events_receiver: Receiver<Vec<FileEvent>>,
 ) -> Result<()> {
     info!("server initialized, serving requests");
+    let mut state = ServerWorldState::new();
+
     let mut next_request_id = 0;
     let mut pending_requests: HashSet<u64> = HashSet::new();
-    let mut path_map = PathMap::new();
-    let mut mem_map: HashMap<FileId, Option<String>> = HashMap::new();
     let mut fs_events_receiver = Some(&fs_events_receiver);
     loop {
         enum Event {
@@ -91,37 +89,17 @@ pub(super) fn main_loop(
             }
             Event::Fs(events) => {
                 trace!("fs change, {} events", events.len());
-                let changes = events.into_iter()
-                    .map(|event| {
-                        let text = match event.kind {
-                            FileEventKind::Add(text) => Some(text),
-                            FileEventKind::Remove => None,
-                        };
-                        (event.path, text)
-                    })
-                    .map(|(path, text)| {
-                        (path_map.get_or_insert(path), text)
-                    })
-                    .filter_map(|(id, text)| {
-                        if mem_map.contains_key(&id) {
-                            mem_map.insert(id, text);
-                            None
-                        } else {
-                            Some((id, text))
-                        }
-                    });
-
-                world.change_files(changes);
+                state.apply_fs_changes(events);
             }
             Event::Msg(msg) => {
                 match msg {
                     RawMsg::Request(req) => {
-                        if !on_request(io, world, &path_map, pool, &task_sender, req)? {
+                        if !on_request(io, &state, pool, &task_sender, req)? {
                             return Ok(());
                         }
                     }
                     RawMsg::Notification(not) => {
-                        on_notification(io, world, &mut path_map, pool, &task_sender, not, &mut mem_map)?
+                        on_notification(io, &mut state, pool, &task_sender, not)?
                     }
                     RawMsg::Response(resp) => {
                         if !pending_requests.remove(&resp.id) {
@@ -136,45 +114,40 @@ pub(super) fn main_loop(
 
 fn on_request(
     io: &mut Io,
-    world: &WorldState,
-    path_map: &PathMap,
+    world: &ServerWorldState,
     pool: &ThreadPool,
     sender: &Sender<Task>,
     req: RawRequest,
 ) -> Result<bool> {
     let mut req = Some(req);
     handle_request_on_threadpool::<req::SyntaxTree>(
-        &mut req, pool, path_map, world, sender, handle_syntax_tree,
+        &mut req, pool, world, sender, handle_syntax_tree,
     )?;
     handle_request_on_threadpool::<req::ExtendSelection>(
-        &mut req, pool, path_map, world, sender, handle_extend_selection,
+        &mut req, pool, world, sender, handle_extend_selection,
     )?;
     handle_request_on_threadpool::<req::FindMatchingBrace>(
-        &mut req, pool, path_map, world, sender, handle_find_matching_brace,
+        &mut req, pool, world, sender, handle_find_matching_brace,
     )?;
     handle_request_on_threadpool::<req::DocumentSymbolRequest>(
-        &mut req, pool, path_map, world, sender, handle_document_symbol,
+        &mut req, pool, world, sender, handle_document_symbol,
     )?;
     handle_request_on_threadpool::<req::CodeActionRequest>(
-        &mut req, pool, path_map, world, sender, handle_code_action,
+        &mut req, pool, world, sender, handle_code_action,
     )?;
     handle_request_on_threadpool::<req::WorkspaceSymbol>(
-        &mut req, pool, path_map, world, sender, handle_workspace_symbol,
+        &mut req, pool, world, sender, handle_workspace_symbol,
     )?;
     handle_request_on_threadpool::<req::GotoDefinition>(
-        &mut req, pool, path_map, world, sender, handle_goto_definition,
+        &mut req, pool, world, sender, handle_goto_definition,
     )?;
     dispatch::handle_request::<req::ExecuteCommand, _>(&mut req, |params, resp| {
         io.send(RawMsg::Response(resp.into_response(Ok(None))?));
 
-        let world = world.snapshot({
-            let pm = path_map.clone();
-            move |id, path| pm.resolve(id, path)
-        });
-        let path_map = path_map.clone();
+        let world = world.snapshot();
         let sender = sender.clone();
         pool.execute(move || {
-            let (edit, cursor) = match handle_execute_command(world, path_map, params) {
+            let (edit, cursor) = match handle_execute_command(world, params) {
                 Ok(res) => res,
                 Err(e) => return sender.send(Task::Die(e)),
             };
@@ -221,60 +194,48 @@ fn on_request(
 
 fn on_notification(
     io: &mut Io,
-    world: &mut WorldState,
-    path_map: &mut PathMap,
+    state: &mut ServerWorldState,
     pool: &ThreadPool,
     sender: &Sender<Task>,
     not: RawNotification,
-    mem_map: &mut HashMap<FileId, Option<String>>,
 ) -> Result<()> {
     let mut not = Some(not);
     dispatch::handle_notification::<req::DidOpenTextDocument, _>(&mut not, |params| {
         let uri = params.text_document.uri;
         let path = uri.to_file_path()
             .map_err(|()| format_err!("invalid uri: {}", uri))?;
-        let file_id = path_map.get_or_insert(path);
-        mem_map.insert(file_id, None);
-        world.change_file(file_id, Some(params.text_document.text));
+        state.add_mem_file(path, params.text_document.text);
         update_file_notifications_on_threadpool(
             pool,
-            world.snapshot({
-                let pm = path_map.clone();
-                move |id, path| pm.resolve(id, path)
-            }),
-            path_map.clone(),
+            state.snapshot(),
             sender.clone(),
             uri,
         );
         Ok(())
     })?;
     dispatch::handle_notification::<req::DidChangeTextDocument, _>(&mut not, |mut params| {
-        let file_id = params.text_document.try_conv_with(path_map)?;
+        let uri = params.text_document.uri;
+        let path = uri.to_file_path()
+            .map_err(|()| format_err!("invalid uri: {}", uri))?;
         let text = params.content_changes.pop()
             .ok_or_else(|| format_err!("empty changes"))?
             .text;
-        world.change_file(file_id, Some(text));
+        state.change_mem_file(path.as_path(), text)?;
         update_file_notifications_on_threadpool(
             pool,
-            world.snapshot({
-                let pm = path_map.clone();
-                move |id, path| pm.resolve(id, path)
-            }),
-            path_map.clone(),
+            state.snapshot(),
             sender.clone(),
-            params.text_document.uri,
+            uri,
         );
         Ok(())
     })?;
     dispatch::handle_notification::<req::DidCloseTextDocument, _>(&mut not, |params| {
-        let file_id = params.text_document.try_conv_with(path_map)?;
-        let text = match mem_map.remove(&file_id) {
-            Some(text) => text,
-            None => bail!("unmatched close notification"),
-        };
-        world.change_file(file_id, text);
+        let uri = params.text_document.uri;
+        let path = uri.to_file_path()
+            .map_err(|()| format_err!("invalid uri: {}", uri))?;
+        state.remove_mem_file(path.as_path())?;
         let not = req::PublishDiagnosticsParams {
-            uri: params.text_document.uri,
+            uri,
             diagnostics: Vec::new(),
         };
         let not = dispatch::send_notification::<req::PublishDiagnostics>(not);
@@ -291,21 +252,16 @@ fn on_notification(
 fn handle_request_on_threadpool<R: req::ClientRequest>(
     req: &mut Option<RawRequest>,
     pool: &ThreadPool,
-    path_map: &PathMap,
-    world: &WorldState,
+    world: &ServerWorldState,
     sender: &Sender<Task>,
-    f: fn(World, PathMap, R::Params) -> Result<R::Result>,
+    f: fn(ServerWorld, R::Params) -> Result<R::Result>,
 ) -> Result<()>
 {
     dispatch::handle_request::<R, _>(req, |params, resp| {
-        let world = world.snapshot({
-            let pm = path_map.clone();
-            move |id, path| pm.resolve(id, path)
-        });
-        let path_map = path_map.clone();
+        let world = world.snapshot();
         let sender = sender.clone();
         pool.execute(move || {
-            let res = f(world, path_map, params);
+            let res = f(world, params);
             let task = match resp.into_response(res) {
                 Ok(resp) => Task::Respond(resp),
                 Err(e) => Task::Die(e),
@@ -318,13 +274,12 @@ fn handle_request_on_threadpool<R: req::ClientRequest>(
 
 fn update_file_notifications_on_threadpool(
     pool: &ThreadPool,
-    world: World,
-    path_map: PathMap,
+    world: ServerWorld,
     sender: Sender<Task>,
     uri: Url,
 ) {
     pool.execute(move || {
-        match publish_diagnostics(world.clone(), path_map.clone(), uri.clone()) {
+        match publish_diagnostics(world.clone(), uri.clone()) {
             Err(e) => {
                 error!("failed to compute diagnostics: {:?}", e)
             }
@@ -333,7 +288,7 @@ fn update_file_notifications_on_threadpool(
                 sender.send(Task::Notify(not));
             }
         }
-        match publish_decorations(world, path_map.clone(), uri) {
+        match publish_decorations(world, uri) {
             Err(e) => {
                 error!("failed to compute decorations: {:?}", e)
             }
diff --git a/crates/server/src/server_world.rs b/crates/server/src/server_world.rs
new file mode 100644
index 000000000..c0d2efb86
--- /dev/null
+++ b/crates/server/src/server_world.rs
@@ -0,0 +1,117 @@
+use std::{
+    path::{PathBuf, Path},
+    collections::HashMap,
+};
+
+use languageserver_types::Url;
+use libanalysis::{FileId, WorldState, World};
+
+use {
+    Result,
+    path_map::PathMap,
+    vfs::{FileEvent, FileEventKind},
+};
+
+#[derive(Debug)]
+pub struct ServerWorldState {
+    pub analysis: WorldState,
+    pub path_map: PathMap,
+    pub mem_map: HashMap<FileId, Option<String>>,
+}
+
+#[derive(Clone)]
+pub struct ServerWorld {
+    pub analysis: World,
+    pub path_map: PathMap,
+}
+
+impl ServerWorldState {
+    pub fn new() -> ServerWorldState {
+        ServerWorldState {
+            analysis: WorldState::new(),
+            path_map: PathMap::new(),
+            mem_map: HashMap::new(),
+        }
+    }
+
+    pub fn apply_fs_changes(&mut self, events: Vec<FileEvent>) {
+        let pm = &mut self.path_map;
+        let mm = &mut self.mem_map;
+        let changes = events.into_iter()
+            .map(|event| {
+                let text = match event.kind {
+                    FileEventKind::Add(text) => Some(text),
+                    FileEventKind::Remove => None,
+                };
+                (event.path, text)
+            })
+            .map(|(path, text)| {
+                (pm.get_or_insert(path), text)
+            })
+            .filter_map(|(id, text)| {
+                if mm.contains_key(&id) {
+                    mm.insert(id, text);
+                    None
+                } else {
+                    Some((id, text))
+                }
+            });
+
+        self.analysis.change_files(changes);
+    }
+
+    pub fn add_mem_file(&mut self, path: PathBuf, text: String) {
+        let file_id = self.path_map.get_or_insert(path);
+        self.mem_map.insert(file_id, None);
+        self.analysis.change_file(file_id, Some(text));
+    }
+
+    pub fn change_mem_file(&mut self, path: &Path, text: String) -> Result<()> {
+        let file_id = self.path_map.get_id(path).ok_or_else(|| {
+            format_err!("change to unknown file: {}", path.display())
+        })?;
+        self.analysis.change_file(file_id, Some(text));
+        Ok(())
+    }
+
+    pub fn remove_mem_file(&mut self, path: &Path) -> Result<()> {
+        let file_id = self.path_map.get_id(path).ok_or_else(|| {
+            format_err!("change to unknown file: {}", path.display())
+        })?;
+        let text = match self.mem_map.remove(&file_id) {
+            Some(text) => text,
+            None => bail!("unmatched close notification"),
+        };
+        self.analysis.change_file(file_id, text);
+        Ok(())
+    }
+
+    pub fn snapshot(&self) -> ServerWorld {
+        let pm = self.path_map.clone();
+        ServerWorld {
+            analysis: self.analysis.snapshot(move |id, path| {
+                pm.resolve(id, path)
+            }),
+            path_map: self.path_map.clone()
+        }
+    }
+}
+
+impl ServerWorld {
+    pub fn analysis(&self) -> &World {
+        &self.analysis
+    }
+
+    pub fn uri_to_file_id(&self, uri: &Url) -> Result<FileId> {
+        let path = uri.to_file_path()
+            .map_err(|()| format_err!("invalid uri: {}", uri))?;
+        self.path_map.get_id(&path).ok_or_else(|| format_err!("unknown file: {}", path.display()))
+    }
+
+    pub fn file_id_to_uri(&self, id: FileId) -> Result<Url> {
+        let path = self.path_map.get_path(id);
+        let url = Url::from_file_path(path)
+            .map_err(|()| format_err!("can't convert path to url: {}", path.display()))?;
+        Ok(url)
+    }
+}