12 files changed, 345 insertions, 183 deletions

diff --git a/code/src/extension.ts b/code/src/extension.ts
index 81153b7e6..3b24b73b6 100644
--- a/code/src/extension.ts
+++ b/code/src/extension.ts
@@ -113,12 +113,26 @@ export function activate(context: vscode.ExtensionContext) {
             return await vscode.tasks.executeTask(task)
         }
     })
-    registerCommand('libsyntax-rust.createFile', async (uri_: string) => {
-        let uri = vscode.Uri.parse(uri_)
+    registerCommand('libsyntax-rust.fsEdit', async (ops: FsOp[]) => {
         let edit = new vscode.WorkspaceEdit()
-        edit.createFile(uri)
+        let created;
+        let moved;
+        for (let op of ops) {
+            if (op.type == "createFile") {
+                let uri = vscode.Uri.parse(op.uri!)
+                edit.createFile(uri)
+                created = uri
+            } else if (op.type == "moveFile") {
+                let src = vscode.Uri.parse(op.src!)
+                let dst = vscode.Uri.parse(op.dst!)
+                edit.renameFile(src, dst)
+                moved = dst
+            } else {
+                console.error(`unknown op: ${JSON.stringify(op)}`)
+            }
+        }
         await vscode.workspace.applyEdit(edit)
-        let doc = await vscode.workspace.openTextDocument(uri)
+        let doc = await vscode.workspace.openTextDocument((created || moved)!)
         await vscode.window.showTextDocument(doc)
     })
 
@@ -368,3 +382,10 @@ function createTask(spec: Runnable): vscode.Task {
     let t = new vscode.Task(definition, f, definition.label, TASK_SOURCE, exec, ['$rustc']);
     return t;
 }
+
+interface FsOp {
+    type: string;
+    uri?: string;
+    src?: string;
+    dst?: string;
+}
diff --git a/crates/libanalysis/Cargo.toml b/crates/libanalysis/Cargo.toml
index a8ef5e5f4..5aca84f0e 100644
--- a/crates/libanalysis/Cargo.toml
+++ b/crates/libanalysis/Cargo.toml
@@ -4,6 +4,7 @@ version = "0.1.0"
 authors = ["Aleksey Kladov <[email protected]>"]
 
 [dependencies]
+relative-path = "0.3.7"
 log = "0.4.2"
 failure = "0.1.2"
 parking_lot = "0.6.3"
diff --git a/crates/libanalysis/src/lib.rs b/crates/libanalysis/src/lib.rs
index fe2c3c2e6..96d10a087 100644
--- a/crates/libanalysis/src/lib.rs
+++ b/crates/libanalysis/src/lib.rs
@@ -8,13 +8,13 @@ extern crate libsyntax2;
 extern crate libeditor;
 extern crate fst;
 extern crate rayon;
+extern crate relative_path;
 
 mod symbol_index;
 mod module_map;
 
 use std::{
     fmt,
-    path::{Path, PathBuf},
     panic,
     sync::{
         Arc,
@@ -24,6 +24,7 @@ use std::{
     time::Instant,
 };
 
+use relative_path::{RelativePath,RelativePathBuf};
 use once_cell::sync::OnceCell;
 use rayon::prelude::*;
 
@@ -37,13 +38,16 @@ use libeditor::{Diagnostic, LineIndex, FileSymbol, find_node_at_offset};
 
 use self::{
     symbol_index::FileSymbols,
-    module_map::{ModuleMap, ChangeKind},
+    module_map::{ModuleMap, ChangeKind, Problem},
 };
 pub use self::symbol_index::Query;
 
 pub type Result<T> = ::std::result::Result<T, ::failure::Error>;
 
-pub type FileResolver = dyn Fn(FileId, &Path) -> Option<FileId> + Send + Sync;
+pub trait FileResolver: Send + Sync + 'static {
+    fn file_stem(&self, id: FileId) -> String;
+    fn resolve(&self, id: FileId, path: &RelativePath) -> Option<FileId>;
+}
 
 #[derive(Debug)]
 pub struct WorldState {
@@ -84,7 +88,7 @@ impl WorldState {
 
     pub fn snapshot(
         &self,
-        file_resolver: impl Fn(FileId, &Path) -> Option<FileId> + 'static + Send + Sync,
+        file_resolver: impl FileResolver,
     ) -> World {
         World {
             needs_reindex: AtomicBool::new(false),
@@ -132,8 +136,20 @@ impl WorldState {
 }
 
 #[derive(Debug)]
-pub enum QuickFix {
-    CreateFile(PathBuf),
+pub struct QuickFix {
+    pub fs_ops: Vec<FsOp>,
+}
+
+#[derive(Debug)]
+pub enum FsOp {
+    CreateFile {
+        anchor: FileId,
+        path: RelativePathBuf,
+    },
+    MoveFile {
+        file: FileId,
+        path: RelativePathBuf,
+    }
 }
 
 impl World {
@@ -221,20 +237,49 @@ impl World {
             .into_iter()
             .map(|d| (d, None))
             .collect::<Vec<_>>();
-        for module in syntax.ast().modules() {
-            if module.has_semi() && self.resolve_module(file_id, module).is_empty() {
-                if let Some(name) = module.name() {
-                    let d = Diagnostic {
-                        range: name.syntax().range(),
-                        msg: "unresolved module".to_string(),
-                    };
-                    let quick_fix = self.data.module_map.suggested_child_mod_path(module)
-                        .map(QuickFix::CreateFile);
-
-                    res.push((d, quick_fix))
-                }
+
+        self.data.module_map.problems(
+            file_id,
+            &*self.file_resolver,
+            &|file_id| self.file_syntax(file_id).unwrap(),
+            |name_node, problem| {
+                let (diag, fix) = match problem {
+                    Problem::UnresolvedModule { candidate } => {
+                        let diag = Diagnostic {
+                            range: name_node.syntax().range(),
+                            msg: "unresolved module".to_string(),
+                        };
+                        let fix = QuickFix {
+                            fs_ops: vec![FsOp::CreateFile {
+                                anchor: file_id,
+                                path: candidate.clone(),
+                            }]
+                        };
+                        (diag, fix)
+                    }
+                    Problem::NotDirOwner { move_to, candidate } => {
+                        let diag = Diagnostic {
+                            range: name_node.syntax().range(),
+                            msg: "can't declare module at this location".to_string(),
+                        };
+                        let fix = QuickFix {
+                            fs_ops: vec![
+                                FsOp::MoveFile {
+                                    file: file_id,
+                                    path: move_to.clone(),
+                                },
+                                FsOp::CreateFile {
+                                    anchor: file_id,
+                                    path: move_to.join(candidate),
+                                }
+                            ],
+                        };
+                        (diag, fix)
+                    }
+                };
+                res.push((diag, Some(fix)))
             }
-        }
+        );
         Ok(res)
     }
 
diff --git a/crates/libanalysis/src/module_map.rs b/crates/libanalysis/src/module_map.rs
index 4f480591e..b65569c46 100644
--- a/crates/libanalysis/src/module_map.rs
+++ b/crates/libanalysis/src/module_map.rs
@@ -1,6 +1,4 @@
-use std::{
-    path::{PathBuf},
-};
+use relative_path::RelativePathBuf;
 
 use parking_lot::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 use libsyntax2::{
@@ -43,6 +41,18 @@ struct Link {
     owner: ModuleId,
     syntax: SyntaxNode,
     points_to: Vec<ModuleId>,
+    problem: Option<Problem>,
+}
+
+#[derive(Clone, Debug)]
+pub enum Problem {
+    UnresolvedModule {
+        candidate: RelativePathBuf,
+    },
+    NotDirOwner {
+        move_to: RelativePathBuf,
+        candidate: RelativePathBuf,
+    }
 }
 
 impl ModuleMap {
@@ -93,9 +103,24 @@ impl ModuleMap {
         res
     }
 
-    pub fn suggested_child_mod_path(&self, m: ast::Module) -> Option<PathBuf> {
-        let name = m.name()?;
-        Some(PathBuf::from(format!("../{}.rs", name.text())))
+    pub fn problems(
+        &self,
+        file: FileId,
+        file_resolver: &FileResolver,
+        syntax_provider: &SyntaxProvider,
+        mut cb: impl FnMut(ast::Name, &Problem),
+    ) {
+        let module = self.file2module(file);
+        let links = self.links(file_resolver, syntax_provider);
+        links
+            .links
+            .iter()
+            .filter(|link| link.owner == module)
+            .filter_map(|link| {
+                let problem = link.problem.as_ref()?;
+                Some((link, problem))
+            })
+            .for_each(|(link, problem)| cb(link.name_node(), problem))
     }
 
     fn links(
@@ -176,14 +201,17 @@ impl Link {
             owner,
             syntax: module.syntax().owned(),
             points_to: Vec::new(),
+            problem: None,
         };
         Some(link)
     }
 
     fn name(&self) -> SmolStr {
-        self.ast().name()
-            .unwrap()
-            .text()
+        self.name_node().text()
+    }
+
+    fn name_node(&self) -> ast::Name {
+        self.ast().name().unwrap()
     }
 
     fn ast(&self) -> ast::Module {
@@ -192,14 +220,30 @@ impl Link {
     }
 
     fn resolve(&mut self, file_resolver: &FileResolver) {
-        let name = self.name();
-        let paths = &[
-            PathBuf::from(format!("../{}.rs", name)),
-            PathBuf::from(format!("../{}/mod.rs", name)),
-        ];
-        self.points_to = paths.iter()
-            .filter_map(|path| file_resolver(self.owner.0, path))
-            .map(ModuleId)
-            .collect();
+        let mod_name = file_resolver.file_stem(self.owner.0);
+        let is_dir_owner =
+            mod_name == "mod" || mod_name == "lib" || mod_name == "main";
+
+        let file_mod = RelativePathBuf::from(format!("../{}.rs", self.name()));
+        let dir_mod = RelativePathBuf::from(format!("../{}/mod.rs", self.name()));
+        if is_dir_owner {
+            self.points_to = [&file_mod, &dir_mod].iter()
+                .filter_map(|path| file_resolver.resolve(self.owner.0, path))
+                .map(ModuleId)
+                .collect();
+            self.problem = if self.points_to.is_empty() {
+                Some(Problem::UnresolvedModule {
+                    candidate: file_mod,
+                })
+            } else {
+                None
+            }
+        } else {
+            self.points_to = Vec::new();
+            self.problem = Some(Problem::NotDirOwner {
+                move_to: RelativePathBuf::from(format!("../{}/mod.rs", mod_name)),
+                candidate: file_mod,
+            });
+        }
     }
 }
diff --git a/crates/libanalysis/tests/tests.rs b/crates/libanalysis/tests/tests.rs
index 7c2950ccc..e378ab986 100644
--- a/crates/libanalysis/tests/tests.rs
+++ b/crates/libanalysis/tests/tests.rs
@@ -1,11 +1,39 @@
 extern crate libanalysis;
+extern crate relative_path;
 extern crate test_utils;
 
-use std::path::PathBuf;
+use std::path::{Path};
 
-use libanalysis::{WorldState, FileId};
+use relative_path::RelativePath;
+use libanalysis::{WorldState, FileId, FileResolver};
 use test_utils::assert_eq_dbg;
 
+struct FileMap(&'static [(u32, &'static str)]);
+
+impl FileMap {
+    fn path(&self, id: FileId) -> &'static Path {
+        let s = self.0.iter()
+            .find(|it| it.0 == id.0)
+            .unwrap()
+            .1;
+        Path::new(s)
+    }
+}
+
+impl FileResolver for FileMap {
+    fn file_stem(&self, id: FileId) -> String {
+        self.path(id).file_stem().unwrap().to_str().unwrap().to_string()
+    }
+    fn resolve(&self, id: FileId, rel: &RelativePath) -> Option<FileId> {
+        let path = rel.to_path(self.path(id));
+        let path = path.to_str().unwrap();
+        let path = RelativePath::new(&path[1..]).normalize();
+        let &(id, _) = self.0.iter()
+            .find(|it| path == RelativePath::new(&it.1[1..]).normalize())?;
+        Some(FileId(id))
+    }
+}
+
 
 #[test]
 fn test_resolve_module() {
@@ -13,14 +41,10 @@ fn test_resolve_module() {
     world.change_file(FileId(1), Some("mod foo;".to_string()));
     world.change_file(FileId(2), Some("".to_string()));
 
-    let snap = world.snapshot(|id, path| {
-        assert_eq!(id, FileId(1));
-        if path == PathBuf::from("../foo/mod.rs") {
-            return None;
-        }
-        assert_eq!(path, PathBuf::from("../foo.rs"));
-        Some(FileId(2))
-    });
+    let snap = world.snapshot(FileMap(&[
+        (1, "/lib.rs"),
+        (2, "/foo.rs"),
+    ]));
     let symbols = snap.approximately_resolve_symbol(FileId(1), 4.into())
         .unwrap();
     assert_eq_dbg(
@@ -28,14 +52,10 @@ fn test_resolve_module() {
         &symbols,
     );
 
-    let snap = world.snapshot(|id, path| {
-        assert_eq!(id, FileId(1));
-        if path == PathBuf::from("../foo.rs") {
-            return None;
-        }
-        assert_eq!(path, PathBuf::from("../foo/mod.rs"));
-        Some(FileId(2))
-    });
+    let snap = world.snapshot(FileMap(&[
+        (1, "/lib.rs"),
+        (2, "/foo/mod.rs")
+    ]));
     let symbols = snap.approximately_resolve_symbol(FileId(1), 4.into())
         .unwrap();
     assert_eq_dbg(
@@ -49,11 +69,11 @@ fn test_unresolved_module_diagnostic() {
     let mut world = WorldState::new();
     world.change_file(FileId(1), Some("mod foo;".to_string()));
 
-    let snap = world.snapshot(|_id, _path| None);
+    let snap = world.snapshot(FileMap(&[(1, "/lib.rs")]));
     let diagnostics = snap.diagnostics(FileId(1)).unwrap();
     assert_eq_dbg(
         r#"[(Diagnostic { range: [4; 7), msg: "unresolved module" },
-             Some(CreateFile("../foo.rs")))]"#,
+             Some(QuickFix { fs_ops: [CreateFile { anchor: FileId(1), path: "../foo.rs" }] }))]"#,
         &diagnostics,
     );
 }
@@ -64,14 +84,10 @@ fn test_resolve_parent_module() {
     world.change_file(FileId(1), Some("mod foo;".to_string()));
     world.change_file(FileId(2), Some("".to_string()));
 
-    let snap = world.snapshot(|id, path| {
-        assert_eq!(id, FileId(1));
-        if path == PathBuf::from("../foo/mod.rs") {
-            return None;
-        }
-        assert_eq!(path, PathBuf::from("../foo.rs"));
-        Some(FileId(2))
-    });
+    let snap = world.snapshot(FileMap(&[
+        (1, "/lib.rs"),
+        (2, "/foo.rs"),
+    ]));
     let symbols = snap.parent_module(FileId(2));
     assert_eq_dbg(
         r#"[(FileId(1), FileSymbol { name: "foo", node_range: [0; 8), kind: MODULE })]"#,
diff --git a/crates/libeditor/src/scope.rs b/crates/libeditor/src/scope/fn_scope.rs
index 3d398a74c..e807c6c71 100644
--- a/crates/libeditor/src/scope.rs
+++ b/crates/libeditor/src/scope/fn_scope.rs
@@ -9,6 +9,95 @@ use libsyntax2::{
     algo::{ancestors, generate, walk::preorder}
 };
 
+type ScopeId = usize;
+
+#[derive(Debug)]
+pub struct FnScopes {
+    scopes: Vec<ScopeData>,
+    scope_for: HashMap<SyntaxNode, ScopeId>,
+}
+
+impl FnScopes {
+    pub fn new(fn_def: ast::FnDef) -> FnScopes {
+        let mut scopes = FnScopes {
+            scopes: Vec::new(),
+            scope_for: HashMap::new()
+        };
+        let root = scopes.root_scope();
+        fn_def.param_list().into_iter()
+            .flat_map(|it| it.params())
+            .filter_map(|it| it.pat())
+            .for_each(|it| scopes.add_bindings(root, it));
+
+        if let Some(body) = fn_def.body() {
+            compute_block_scopes(body, &mut scopes, root)
+        }
+        scopes
+    }
+    pub fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
+        &self.scopes[scope].entries
+    }
+    pub fn scope_chain<'a>(&'a self, node: SyntaxNodeRef) -> impl Iterator<Item=ScopeId> + 'a {
+        generate(self.scope_for(node), move |&scope| self.scopes[scope].parent)
+    }
+    fn root_scope(&mut self) -> ScopeId {
+        let res = self.scopes.len();
+        self.scopes.push(ScopeData { parent: None, entries: vec![] });
+        res
+    }
+    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
+        let res = self.scopes.len();
+        self.scopes.push(ScopeData { parent: Some(parent), entries: vec![] });
+        res
+    }
+    fn add_bindings(&mut self, scope: ScopeId, pat: ast::Pat) {
+        let entries = preorder(pat.syntax())
+            .filter_map(ast::BindPat::cast)
+            .filter_map(ScopeEntry::new);
+        self.scopes[scope].entries.extend(entries);
+    }
+    fn set_scope(&mut self, node: SyntaxNodeRef, scope: ScopeId) {
+        self.scope_for.insert(node.owned(), scope);
+    }
+    fn scope_for(&self, node: SyntaxNodeRef) -> Option<ScopeId> {
+        ancestors(node)
+            .filter_map(|it| self.scope_for.get(&it.owned()).map(|&scope| scope))
+            .next()
+    }
+}
+
+pub struct ScopeEntry {
+    syntax: SyntaxNode
+}
+
+impl ScopeEntry {
+    fn new(pat: ast::BindPat) -> Option<ScopeEntry> {
+        if pat.name().is_some() {
+            Some(ScopeEntry { syntax: pat.syntax().owned() })
+        } else {
+            None
+        }
+    }
+    pub fn name(&self) -> SmolStr {
+        self.ast().name()
+            .unwrap()
+            .text()
+    }
+    fn ast(&self) -> ast::BindPat {
+        ast::BindPat::cast(self.syntax.borrowed())
+            .unwrap()
+    }
+}
+
+impl fmt::Debug for ScopeEntry {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("ScopeEntry")
+         .field("name", &self.name())
+         .field("syntax", &self.syntax)
+         .finish()
+    }
+}
+
 fn compute_block_scopes(block: ast::Block, scopes: &mut FnScopes, mut scope: ScopeId) {
     for stmt in block.statements() {
         match stmt {
@@ -95,97 +184,8 @@ fn compute_expr_scopes(expr: ast::Expr, scopes: &mut FnScopes, scope: ScopeId) {
     }
 }
 
-type ScopeId = usize;
-
-#[derive(Debug)]
-pub struct FnScopes {
-    scopes: Vec<ScopeData>,
-    scope_for: HashMap<SyntaxNode, ScopeId>,
-}
-
-impl FnScopes {
-    pub fn new(fn_def: ast::FnDef) -> FnScopes {
-        let mut scopes = FnScopes {
-            scopes: Vec::new(),
-            scope_for: HashMap::new()
-        };
-        let root = scopes.root_scope();
-        fn_def.param_list().into_iter()
-            .flat_map(|it| it.params())
-            .filter_map(|it| it.pat())
-            .for_each(|it| scopes.add_bindings(root, it));
-
-        if let Some(body) = fn_def.body() {
-            compute_block_scopes(body, &mut scopes, root)
-        }
-        scopes
-    }
-    pub fn entries(&self, scope: ScopeId) -> &[ScopeEntry] {
-        &self.scopes[scope].entries
-    }
-    pub fn scope_chain<'a>(&'a self, node: SyntaxNodeRef) -> impl Iterator<Item=ScopeId> + 'a {
-        generate(self.scope_for(node), move |&scope| self.scopes[scope].parent)
-    }
-    fn root_scope(&mut self) -> ScopeId {
-        let res = self.scopes.len();
-        self.scopes.push(ScopeData { parent: None, entries: vec![] });
-        res
-    }
-    fn new_scope(&mut self, parent: ScopeId) -> ScopeId {
-        let res = self.scopes.len();
-        self.scopes.push(ScopeData { parent: Some(parent), entries: vec![] });
-        res
-    }
-    fn add_bindings(&mut self, scope: ScopeId, pat: ast::Pat) {
-        let entries = preorder(pat.syntax())
-            .filter_map(ast::BindPat::cast)
-            .filter_map(ScopeEntry::new);
-        self.scopes[scope].entries.extend(entries);
-    }
-    fn set_scope(&mut self, node: SyntaxNodeRef, scope: ScopeId) {
-        self.scope_for.insert(node.owned(), scope);
-    }
-    fn scope_for(&self, node: SyntaxNodeRef) -> Option<ScopeId> {
-        ancestors(node)
-            .filter_map(|it| self.scope_for.get(&it.owned()).map(|&scope| scope))
-            .next()
-    }
-}
-
 #[derive(Debug)]
 struct ScopeData {
     parent: Option<ScopeId>,
     entries: Vec<ScopeEntry>
 }
-
-pub struct ScopeEntry {
-    syntax: SyntaxNode
-}
-
-impl ScopeEntry {
-    fn new(pat: ast::BindPat) -> Option<ScopeEntry> {
-        if pat.name().is_some() {
-            Some(ScopeEntry { syntax: pat.syntax().owned() })
-        } else {
-            None
-        }
-    }
-    pub fn name(&self) -> SmolStr {
-        self.ast().name()
-            .unwrap()
-            .text()
-    }
-    fn ast(&self) -> ast::BindPat {
-        ast::BindPat::cast(self.syntax.borrowed())
-            .unwrap()
-    }
-}
-
-impl fmt::Debug for ScopeEntry {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("ScopeEntry")
-         .field("name", &self.name())
-         .field("syntax", &self.syntax)
-         .finish()
-    }
-}
diff --git a/crates/libeditor/src/scope/mod.rs b/crates/libeditor/src/scope/mod.rs
new file mode 100644
index 000000000..1a77a8b6e
--- /dev/null
+++ b/crates/libeditor/src/scope/mod.rs
@@ -0,0 +1,3 @@
+mod fn_scope;
+
+pub use self::fn_scope::FnScopes;
diff --git a/crates/server/Cargo.toml b/crates/server/Cargo.toml
index 058bf36d2..35ced91ac 100644
--- a/crates/server/Cargo.toml
+++ b/crates/server/Cargo.toml
@@ -4,6 +4,7 @@ version = "0.1.0"
 authors = ["Aleksey Kladov <[email protected]>"]
 
 [dependencies]
+relative-path = "0.3.7"
 failure = "0.1.2"
 serde_json = "1.0.24"
 serde = "1.0.71"
diff --git a/crates/server/src/main.rs b/crates/server/src/main.rs
index 615dd082c..1a93af65b 100644
--- a/crates/server/src/main.rs
+++ b/crates/server/src/main.rs
@@ -18,6 +18,7 @@ extern crate libeditor;
 extern crate libanalysis;
 extern crate libsyntax2;
 extern crate im;
+extern crate relative_path;
 
 mod io;
 mod caps;
diff --git a/crates/server/src/main_loop/handlers.rs b/crates/server/src/main_loop/handlers.rs
index ca5cd5ab1..92ffb30c3 100644
--- a/crates/server/src/main_loop/handlers.rs
+++ b/crates/server/src/main_loop/handlers.rs
@@ -7,7 +7,8 @@ use languageserver_types::{
     CompletionItem,
 };
 use serde_json::{to_value, from_value};
-use libanalysis::{Query, QuickFix, FileId};
+use url_serde;
+use libanalysis::{self, Query, FileId};
 use libeditor;
 use libsyntax2::{
     TextUnit,
@@ -144,24 +145,49 @@ pub fn handle_code_action(
         if !contains_offset_nonstrict(diag.range, offset) {
             continue;
         }
-        let cmd = match quick_fix {
-            QuickFix::CreateFile(path) => {
-                let path = &path.to_str().unwrap()[3..]; // strip `../` b/c url is weird
-                let uri = params.text_document.uri.join(path)
-                    .unwrap();
-                let uri = ::url_serde::Ser::new(&uri);
-                Command {
-                    title: "Create file".to_string(),
-                    command: "libsyntax-rust.createFile".to_string(),
-                    arguments: Some(vec![to_value(uri).unwrap()]),
-                }
-            }
+        let mut ops = Vec::new();
+        for op in quick_fix.fs_ops {
+            let op = match op {
+                libanalysis::FsOp::CreateFile { anchor, path } => {
+                    let uri = world.file_id_to_uri(anchor)?;
+                    let path = &path.as_str()[3..]; // strip `../` b/c url is weird
+                    let uri = uri.join(path)?;
+                    FsOp::CreateFile { uri }
+                },
+                libanalysis::FsOp::MoveFile { file, path } => {
+                    let src = world.file_id_to_uri(file)?;
+                    let path = &path.as_str()[3..]; // strip `../` b/c url is weird
+                    let dst = src.join(path)?;
+                    FsOp::MoveFile { src, dst }
+                },
+            };
+            ops.push(op)
+        }
+        let cmd = Command {
+            title: "Create module".to_string(),
+            command: "libsyntax-rust.fsEdit".to_string(),
+            arguments: Some(vec![to_value(ops).unwrap()]),
         };
         res.push(cmd)
     }
     return Ok(Some(res));
 }
 
+#[derive(Serialize)]
+#[serde(tag = "type", rename_all = "camelCase")]
+enum FsOp {
+    CreateFile {
+        #[serde(with = "url_serde")]
+        uri: Url
+    },
+    MoveFile {
+        #[serde(with = "url_serde")]
+        src: Url,
+        #[serde(with = "url_serde")]
+        dst: Url,
+    }
+}
+
 pub fn handle_runnables(
     world: ServerWorld,
     params: req::RunnablesParams,
diff --git a/crates/server/src/path_map.rs b/crates/server/src/path_map.rs
index d2b811a3b..f4ac47e70 100644
--- a/crates/server/src/path_map.rs
+++ b/crates/server/src/path_map.rs
@@ -1,6 +1,7 @@
 use std::path::{PathBuf, Path, Component};
 use im;
-use libanalysis::{FileId};
+use relative_path::RelativePath;
+use libanalysis::{FileId, FileResolver};
 
 #[derive(Debug, Default, Clone)]
 pub struct PathMap {
@@ -34,12 +35,6 @@ impl PathMap {
             .as_path()
     }
 
-    pub fn resolve(&self, id: FileId, relpath: &Path) -> Option<FileId> {
-        let path = self.get_path(id).join(relpath);
-        let path = normalize(&path);
-        self.get_id(&path)
-    }
-
     fn insert(&mut self, path: PathBuf, id: FileId) {
         self.path2id.insert(path.clone(), id);
         self.id2path.insert(id, path.clone());
@@ -52,6 +47,18 @@ impl PathMap {
     }
 }
 
+impl FileResolver for PathMap {
+    fn file_stem(&self, id: FileId) -> String {
+        self.get_path(id).file_stem().unwrap().to_str().unwrap().to_string()
+    }
+
+    fn resolve(&self, id: FileId, path: &RelativePath) -> Option<FileId> {
+        let path = path.to_path(&self.get_path(id));
+        let path = normalize(&path);
+        self.get_id(&path)
+    }
+}
+
 fn normalize(path: &Path) -> PathBuf {
     let mut components = path.components().peekable();
     let mut ret = if let Some(c @ Component::Prefix(..)) = components.peek().cloned() {
@@ -89,7 +96,7 @@ mod test {
         let id1 = m.get_or_insert(PathBuf::from("/foo"));
         let id2 = m.get_or_insert(PathBuf::from("/foo/bar.rs"));
         assert_eq!(
-            m.resolve(id1, &PathBuf::from("bar.rs")),
+            m.resolve(id1, &RelativePath::new("bar.rs")),
             Some(id2),
         )
     }
diff --git a/crates/server/src/server_world.rs b/crates/server/src/server_world.rs
index c0d2efb86..1593cd59f 100644
--- a/crates/server/src/server_world.rs
+++ b/crates/server/src/server_world.rs
@@ -87,11 +87,8 @@ impl ServerWorldState {
     }
 
     pub fn snapshot(&self) -> ServerWorld {
-        let pm = self.path_map.clone();
         ServerWorld {
-            analysis: self.analysis.snapshot(move |id, path| {
-                pm.resolve(id, path)
-            }),
+            analysis: self.analysis.snapshot(self.path_map.clone()),
             path_map: self.path_map.clone()
         }
     }