9 files changed, 109 insertions, 14 deletions

diff --git a/crates/libanalysis/src/lib.rs b/crates/libanalysis/src/lib.rs
index b2f4bdbb3..97b6dfca6 100644
--- a/crates/libanalysis/src/lib.rs
+++ b/crates/libanalysis/src/lib.rs
@@ -18,10 +18,14 @@ use std::{
     path::{PathBuf, Path},
 };
 
-use libsyntax2::ast;
+use libsyntax2::{
+    TextUnit,
+    ast::{self, AstNode},
+    algo::{find_leaf_at_offset, ancestors},
+};
 use libeditor::{LineIndex, FileSymbol};
 
-use self::symbol_index::{FileSymbols};
+use self::symbol_index::FileSymbols;
 pub use self::symbol_index::Query;
 
 pub type Result<T> = ::std::result::Result<T, ::failure::Error>;
@@ -90,8 +94,7 @@ impl World {
         Ok(index.clone())
     }
 
-    pub fn world_symbols<'a>(&'a self, query: Query) -> impl Iterator<Item=(&'a Path, &'a FileSymbol)> + 'a
-    {
+    pub fn world_symbols<'a>(&'a self, query: Query) -> impl Iterator<Item=(&'a Path, &'a FileSymbol)> + 'a {
         self.data.file_map.iter()
             .flat_map(move |(path, data)| {
                 let path: &'a Path = path.as_path();
@@ -100,6 +103,31 @@ impl World {
             })
     }
 
+    pub fn approximately_resolve_symbol<'a>(
+        &'a self,
+        path: &Path,
+        offset: TextUnit,
+    ) -> Result<Vec<(&'a Path, &'a FileSymbol)>> {
+        let file = self.file_syntax(path)?;
+        let syntax = file.syntax();
+        let syntax = syntax.as_ref();
+        let name_ref =
+            find_leaf_at_offset(syntax, offset)
+                .left_biased()
+                .into_iter()
+                .flat_map(|node| ancestors(node))
+                .flat_map(ast::NameRef::cast)
+                .next();
+        let name = match name_ref {
+            None => return Ok(vec![]),
+            Some(name_ref) => name_ref.text(),
+        };
+
+        let mut query = Query::new(name.to_string());
+        query.exact();
+        Ok(self.world_symbols(query).take(4).collect())
+    }
+
     fn file_data(&self, path: &Path) -> Result<Arc<FileData>> {
         match self.data.file_map.get(path) {
             Some(data) => Ok(data.clone()),
diff --git a/crates/libsyntax2/src/ast/generated.rs b/crates/libsyntax2/src/ast/generated.rs
index 31f5ecc44..b1fd0a8ad 100644
--- a/crates/libsyntax2/src/ast/generated.rs
+++ b/crates/libsyntax2/src/ast/generated.rs
@@ -123,6 +123,24 @@ impl<R: TreeRoot> AstNode<R> for Name<R> {
 
 impl<R: TreeRoot> Name<R> {}
 
+// NameRef
+#[derive(Debug, Clone, Copy)]
+pub struct NameRef<R: TreeRoot = Arc<SyntaxRoot>> {
+    syntax: SyntaxNode<R>,
+}
+
+impl<R: TreeRoot> AstNode<R> for NameRef<R> {
+    fn cast(syntax: SyntaxNode<R>) -> Option<Self> {
+        match syntax.kind() {
+            NAME_REF => Some(NameRef { syntax }),
+            _ => None,
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode<R> { &self.syntax }
+}
+
+impl<R: TreeRoot> NameRef<R> {}
+
 // StaticItem
 #[derive(Debug, Clone, Copy)]
 pub struct StaticItem<R: TreeRoot = Arc<SyntaxRoot>> {
diff --git a/crates/libsyntax2/src/ast/mod.rs b/crates/libsyntax2/src/ast/mod.rs
index e9362d048..2e1fb2d1c 100644
--- a/crates/libsyntax2/src/ast/mod.rs
+++ b/crates/libsyntax2/src/ast/mod.rs
@@ -73,3 +73,11 @@ impl<R: TreeRoot> Name<R> {
         ident.leaf_text().unwrap()
     }
 }
+
+impl<R: TreeRoot> NameRef<R> {
+    pub fn text(&self) -> SmolStr {
+        let ident = self.syntax().first_child()
+            .unwrap();
+        ident.leaf_text().unwrap()
+    }
+}
diff --git a/crates/libsyntax2/src/grammar.ron b/crates/libsyntax2/src/grammar.ron
index d4e8c53d3..ee231931e 100644
--- a/crates/libsyntax2/src/grammar.ron
+++ b/crates/libsyntax2/src/grammar.ron
@@ -228,5 +228,6 @@ Grammar(
         "StaticItem": ( traits: ["NameOwner"] ),
         "TypeItem": ( traits: ["NameOwner"] ),
         "Name": (),
+        "NameRef": (),
     },
 )
diff --git a/crates/server/src/caps.rs b/crates/server/src/caps.rs
index 4fd28b7c8..ffebd9b47 100644
--- a/crates/server/src/caps.rs
+++ b/crates/server/src/caps.rs
@@ -20,7 +20,7 @@ pub fn server_capabilities() -> ServerCapabilities {
         hover_provider: None,
         completion_provider: None,
         signature_help_provider: None,
-        definition_provider: None,
+        definition_provider: Some(true),
         type_definition_provider: None,
         implementation_provider: None,
         references_provider: None,
diff --git a/crates/server/src/conv.rs b/crates/server/src/conv.rs
index 0ed989b32..1c31d32fe 100644
--- a/crates/server/src/conv.rs
+++ b/crates/server/src/conv.rs
@@ -1,7 +1,11 @@
-use languageserver_types::{Range, SymbolKind, Position, TextEdit};
+use std::path::Path;
+
+use languageserver_types::{Range, SymbolKind, Position, TextEdit, Location, Url};
 use libeditor::{LineIndex, LineCol, Edit, AtomEdit};
 use libsyntax2::{SyntaxKind, TextUnit, TextRange};
 
+use Result;
+
 pub trait Conv {
     type Output;
     fn conv(self) -> Self::Output;
@@ -13,6 +17,12 @@ pub trait ConvWith {
     fn conv_with(self, ctx: &Self::Ctx) -> Self::Output;
 }
 
+pub trait TryConvWith {
+    type Ctx;
+    type Output;
+    fn try_conv_with(self, ctx: &Self::Ctx) -> Result<Self::Output>;
+}
+
 impl Conv for SyntaxKind {
     type Output = SymbolKind;
 
@@ -104,6 +114,20 @@ impl ConvWith for AtomEdit {
     }
 }
 
+impl<'a> TryConvWith for (&'a Path, TextRange) {
+    type Ctx = LineIndex;
+    type Output = Location;
+
+    fn try_conv_with(self, line_index: &LineIndex) -> Result<Location> {
+        let loc = Location::new(
+            Url::from_file_path(self.0)
+                .map_err(|()| format_err!("can't convert path to url: {}", self.0.display()))?,
+            self.1.conv_with(line_index),
+        );
+        Ok(loc)
+    }
+}
+
 
 pub trait MapConvWith<'a>: Sized {
     type Ctx;
diff --git a/crates/server/src/main_loop/handlers.rs b/crates/server/src/main_loop/handlers.rs
index f51909280..e9dc78420 100644
--- a/crates/server/src/main_loop/handlers.rs
+++ b/crates/server/src/main_loop/handlers.rs
@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use languageserver_types::{
     Diagnostic, DiagnosticSeverity, Url, DocumentSymbol,
     Command, TextDocumentIdentifier, WorkspaceEdit,
-    SymbolInformation, Location,
+    SymbolInformation,
 };
 use libanalysis::{World, Query};
 use libeditor;
@@ -13,7 +13,7 @@ use serde_json::{to_value, from_value};
 use ::{
     req::{self, Decoration}, Result,
     util::FilePath,
-    conv::{Conv, ConvWith, MapConvWith},
+    conv::{Conv, ConvWith, TryConvWith, MapConvWith},
 };
 
 pub fn handle_syntax_tree(
@@ -115,15 +115,10 @@ pub fn handle_workspace_symbol(
 
     for (path, symbol) in world.world_symbols(query).take(128) {
         let line_index = world.file_line_index(path)?;
-
         let info = SymbolInformation {
             name: symbol.name.to_string(),
             kind: symbol.kind.conv(),
-            location: Location::new(
-                Url::from_file_path(path)
-                    .map_err(|()| format_err!("invalid url"))?,
-                symbol.node_range.conv_with(&line_index),
-            ),
+            location: (path, symbol.node_range).try_conv_with(&line_index)?,
             container_name: None,
         };
         acc.push(info);
@@ -132,6 +127,22 @@ pub fn handle_workspace_symbol(
     Ok(Some(acc))
 }
 
+pub fn handle_goto_definition(
+    world: World,
+    params: req::TextDocumentPositionParams,
+) -> Result<Option<req::GotoDefinitionResponse>> {
+    let path = params.text_document.file_path()?;
+    let line_index = world.file_line_index(&path)?;
+    let offset = params.position.conv_with(&line_index);
+    let mut res = Vec::new();
+    for (path, symbol) in world.approximately_resolve_symbol(&path, offset)? {
+        let line_index = world.file_line_index(path)?;
+        let location = (path, symbol.node_range).try_conv_with(&line_index)?;
+        res.push(location)
+    }
+    Ok(Some(req::GotoDefinitionResponse::Array(res)))
+}
+
 pub fn handle_execute_command(
     world: World,
     mut params: req::ExecuteCommandParams,
diff --git a/crates/server/src/main_loop/mod.rs b/crates/server/src/main_loop/mod.rs
index e8b24355c..bc898c17b 100644
--- a/crates/server/src/main_loop/mod.rs
+++ b/crates/server/src/main_loop/mod.rs
@@ -26,6 +26,7 @@ use {
         handle_code_action,
         handle_execute_command,
         handle_workspace_symbol,
+        handle_goto_definition,
     },
 };
 
@@ -152,6 +153,9 @@ fn on_request(
     handle_request_on_threadpool::<req::WorkspaceSymbol>(
         &mut req, pool, world, sender, handle_workspace_symbol,
     )?;
+    handle_request_on_threadpool::<req::GotoDefinition>(
+        &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))?));
 
diff --git a/crates/server/src/req.rs b/crates/server/src/req.rs
index a8cc9b537..17ef10e43 100644
--- a/crates/server/src/req.rs
+++ b/crates/server/src/req.rs
@@ -9,6 +9,7 @@ pub use languageserver_types::{
     CodeActionParams, ApplyWorkspaceEditParams,
     ExecuteCommandParams,
     WorkspaceSymbolParams,
+    TextDocumentPositionParams,
 };