10 files changed, 59 insertions, 17 deletions

diff --git a/crates/ra_lsp_server/src/caps.rs b/crates/ra_lsp_server/src/caps.rs
index 3c628f29c..5598ec75f 100644
--- a/crates/ra_lsp_server/src/caps.rs
+++ b/crates/ra_lsp_server/src/caps.rs
@@ -7,6 +7,7 @@ use languageserver_types::{
     TextDocumentSyncKind,
     ExecuteCommandOptions,
     CompletionOptions,
+    SignatureHelpOptions,
     DocumentOnTypeFormattingOptions,
 };
 
@@ -26,7 +27,9 @@ pub fn server_capabilities() -> ServerCapabilities {
             resolve_provider: None,
             trigger_characters: None,
         }),
-        signature_help_provider: None,
+        signature_help_provider: Some(SignatureHelpOptions {
+            trigger_characters: Some(vec!["(".to_string(), ",".to_string()])
+        }),
         definition_provider: Some(true),
         type_definition_provider: None,
         implementation_provider: None,
diff --git a/crates/ra_lsp_server/src/conv.rs b/crates/ra_lsp_server/src/conv.rs
index 08a656569..a75b160c5 100644
--- a/crates/ra_lsp_server/src/conv.rs
+++ b/crates/ra_lsp_server/src/conv.rs
@@ -7,7 +7,7 @@ use ra_editor::{LineIndex, LineCol, Edit, AtomEdit};
 use ra_syntax::{SyntaxKind, TextUnit, TextRange};
 use ra_analysis::{FileId, SourceChange, SourceFileEdit, FileSystemEdit};
 
-use {
+use crate::{
     Result,
     server_world::ServerWorld,
     req,
@@ -299,7 +299,7 @@ pub fn to_location(
         Ok(loc)
 }
 
-pub trait MapConvWith<'a>: Sized {
+pub trait MapConvWith<'a>: Sized + 'a {
     type Ctx;
     type Output;
 
@@ -309,7 +309,7 @@ pub trait MapConvWith<'a>: Sized {
 }
 
 impl<'a, I> MapConvWith<'a> for I
-    where I: Iterator,
+    where I: Iterator + 'a,
           I::Item: ConvWith
 {
     type Ctx = <I::Item as ConvWith>::Ctx;
diff --git a/crates/ra_lsp_server/src/lib.rs b/crates/ra_lsp_server/src/lib.rs
index 60652d55e..7224b1476 100644
--- a/crates/ra_lsp_server/src/lib.rs
+++ b/crates/ra_lsp_server/src/lib.rs
@@ -34,5 +34,7 @@ mod project_model;
 pub mod thread_watcher;
 
 pub type Result<T> = ::std::result::Result<T, ::failure::Error>;
-pub use caps::server_capabilities;
-pub use main_loop::main_loop;
+pub use crate::{
+    main_loop::main_loop,
+    caps::server_capabilities,
+};
diff --git a/crates/ra_lsp_server/src/main_loop/handlers.rs b/crates/ra_lsp_server/src/main_loop/handlers.rs
index ab8be15e9..5acb39b60 100644
--- a/crates/ra_lsp_server/src/main_loop/handlers.rs
+++ b/crates/ra_lsp_server/src/main_loop/handlers.rs
@@ -13,7 +13,7 @@ use ra_syntax::{
     text_utils::contains_offset_nonstrict
 };
 
-use ::{
+use crate::{
     req::{self, Decoration}, Result,
     conv::{Conv, ConvWith, TryConvWith, MapConvWith, to_location},
     server_world::ServerWorld,
@@ -411,6 +411,42 @@ pub fn handle_folding_range(
     Ok(res)
 }
 
+pub fn handle_signature_help(
+    world: ServerWorld,
+    params: req::TextDocumentPositionParams,
+    token: JobToken,
+) -> Result<Option<req::SignatureHelp>> {
+    use languageserver_types::{ParameterInformation, SignatureInformation};
+
+    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);
+
+    if let Some((descriptor, active_param)) = world.analysis().resolve_callable(file_id, offset, &token) {
+        let parameters : Vec<ParameterInformation> =
+            descriptor.params.iter().map(|param|
+                ParameterInformation {
+                    label: param.clone(),
+                    documentation: None
+                }
+            ).collect();
+
+        let sig_info = SignatureInformation {
+            label: descriptor.label,
+            documentation: None,
+            parameters: Some(parameters)
+        };
+
+        Ok(Some(req::SignatureHelp {
+            signatures: vec![sig_info],
+            active_signature: Some(0),
+            active_parameter: active_param.map(|a| a as u64)
+        }))
+    } else {
+        Ok(None)
+    }
+}
+
 pub fn handle_code_action(
     world: ServerWorld,
     params: req::CodeActionParams,
@@ -442,7 +478,7 @@ pub fn handle_code_action(
 }
 
 pub fn publish_diagnostics(
-    world: ServerWorld,
+    world: &ServerWorld,
     file_id: FileId,
 ) -> Result<req::PublishDiagnosticsParams> {
     let uri = world.file_id_to_uri(file_id)?;
@@ -461,7 +497,7 @@ pub fn publish_diagnostics(
 }
 
 pub fn publish_decorations(
-    world: ServerWorld,
+    world: &ServerWorld,
     file_id: FileId,
 ) -> Result<req::PublishDecorationsParams> {
     let uri = world.file_id_to_uri(file_id)?;
diff --git a/crates/ra_lsp_server/src/main_loop/mod.rs b/crates/ra_lsp_server/src/main_loop/mod.rs
index 402615e42..cf2477cb5 100644
--- a/crates/ra_lsp_server/src/main_loop/mod.rs
+++ b/crates/ra_lsp_server/src/main_loop/mod.rs
@@ -16,7 +16,7 @@ use gen_lsp_server::{
 };
 use rustc_hash::FxHashMap;
 
-use {
+use crate::{
     req,
     Result,
     vfs::{self, FileEvent},
@@ -255,6 +255,7 @@ fn on_request(
         .on::<req::Completion>(handlers::handle_completion)?
         .on::<req::CodeActionRequest>(handlers::handle_code_action)?
         .on::<req::FoldingRangeRequest>(handlers::handle_folding_range)?
+        .on::<req::SignatureHelpRequest>(handlers::handle_signature_help)?
         .finish();
     match req {
         Ok((id, handle)) => {
@@ -390,7 +391,7 @@ fn update_file_notifications_on_threadpool(
 ) {
     pool.spawn(move || {
         for file_id in subscriptions {
-            match handlers::publish_diagnostics(world.clone(), file_id) {
+            match handlers::publish_diagnostics(&world, file_id) {
                 Err(e) => {
                     error!("failed to compute diagnostics: {:?}", e)
                 }
@@ -399,7 +400,7 @@ fn update_file_notifications_on_threadpool(
                     sender.send(Task::Notify(not));
                 }
             }
-            match handlers::publish_decorations(world.clone(), file_id) {
+            match handlers::publish_decorations(&world, file_id) {
                 Err(e) => {
                     error!("failed to compute decorations: {:?}", e)
                 }
diff --git a/crates/ra_lsp_server/src/project_model.rs b/crates/ra_lsp_server/src/project_model.rs
index 43e4fd654..c144d9596 100644
--- a/crates/ra_lsp_server/src/project_model.rs
+++ b/crates/ra_lsp_server/src/project_model.rs
@@ -5,7 +5,7 @@ use rustc_hash::{FxHashMap, FxHashSet};
 use cargo_metadata::{metadata_run, CargoOpt};
 use ra_syntax::SmolStr;
 
-use {
+use crate::{
     Result,
     thread_watcher::{Worker, ThreadWatcher},
 };
diff --git a/crates/ra_lsp_server/src/req.rs b/crates/ra_lsp_server/src/req.rs
index f80957589..1630edf7f 100644
--- a/crates/ra_lsp_server/src/req.rs
+++ b/crates/ra_lsp_server/src/req.rs
@@ -14,6 +14,7 @@ pub use languageserver_types::{
     CompletionParams, CompletionResponse,
     DocumentOnTypeFormattingParams,
     TextDocumentEdit,
+    SignatureHelp, Hover
 };
 
 pub enum SyntaxTree {}
diff --git a/crates/ra_lsp_server/src/server_world.rs b/crates/ra_lsp_server/src/server_world.rs
index c4cdf83d4..9b3013ae8 100644
--- a/crates/ra_lsp_server/src/server_world.rs
+++ b/crates/ra_lsp_server/src/server_world.rs
@@ -8,7 +8,7 @@ use rustc_hash::FxHashMap;
 use languageserver_types::Url;
 use ra_analysis::{FileId, AnalysisHost, Analysis, CrateGraph, CrateId, LibraryData, FileResolver};
 
-use {
+use crate::{
     Result,
     path_map::{PathMap, Root},
     vfs::{FileEvent, FileEventKind},
@@ -23,7 +23,6 @@ pub struct ServerWorldState {
     pub mem_map: FxHashMap<FileId, Option<String>>,
 }
 
-#[derive(Clone)]
 pub struct ServerWorld {
     pub workspaces: Arc<Vec<CargoWorkspace>>,
     pub analysis: Analysis,
diff --git a/crates/ra_lsp_server/src/thread_watcher.rs b/crates/ra_lsp_server/src/thread_watcher.rs
index 86a3a91e0..3257effcb 100644
--- a/crates/ra_lsp_server/src/thread_watcher.rs
+++ b/crates/ra_lsp_server/src/thread_watcher.rs
@@ -1,7 +1,7 @@
 use std::thread;
 use crossbeam_channel::{bounded, unbounded, Sender, Receiver};
 use drop_bomb::DropBomb;
-use Result;
+use crate::Result;
 
 pub struct Worker<I, O> {
     pub inp: Sender<I>,
diff --git a/crates/ra_lsp_server/src/vfs.rs b/crates/ra_lsp_server/src/vfs.rs
index a1c1783f2..d8f9b1aac 100644
--- a/crates/ra_lsp_server/src/vfs.rs
+++ b/crates/ra_lsp_server/src/vfs.rs
@@ -5,7 +5,7 @@ use std::{
 
 use walkdir::WalkDir;
 
-use {
+use crate::{
     thread_watcher::{Worker, ThreadWatcher},
 };