12 files changed, 247 insertions, 118 deletions

diff --git a/code/package.json b/code/package.json
index 327fbfb81..eef16522f 100644
--- a/code/package.json
+++ b/code/package.json
@@ -10,7 +10,8 @@
     "vscode": "^1.25.0"
   },
   "scripts": {
-    "compile": "tsc -p ./",
+    "vscode:prepublish": "tsc -p ./",
+    "compile": "tsc -watch -p ./",
     "postinstall": "node ./node_modules/vscode/bin/install"
   },
   "dependencies": {
diff --git a/crates/libeditor/src/edit.rs b/crates/libeditor/src/edit.rs
index 163ecf6de..15a2a904f 100644
--- a/crates/libeditor/src/edit.rs
+++ b/crates/libeditor/src/edit.rs
@@ -1,11 +1,11 @@
 use {TextRange, TextUnit};
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct Edit {
-    pub atoms: Vec<AtomEdit>,
+    atoms: Vec<AtomEdit>,
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct AtomEdit {
     pub delete: TextRange,
     pub insert: String,
@@ -22,7 +22,6 @@ impl EditBuilder {
     }
 
     pub fn replace(&mut self, range: TextRange, replacement: String) {
-        let range = self.translate(range);
         self.atoms.push(AtomEdit { delete: range, insert: replacement })
     }
 
@@ -35,59 +34,47 @@ impl EditBuilder {
     }
 
     pub fn finish(self) -> Edit {
-        Edit { atoms: self.atoms }
-    }
-
-    fn translate(&self, range: TextRange) -> TextRange {
-        let mut range = range;
-        for atom in self.atoms.iter() {
-            range = atom.apply_to_range(range)
-                .expect("conflicting edits");
+        let mut atoms = self.atoms;
+        atoms.sort_by_key(|a| a.delete.start());
+        for (a1, a2) in atoms.iter().zip(atoms.iter().skip(1)) {
+            assert!(a1.end() <= a2.start())
         }
-        range
+        Edit { atoms }
     }
 }
 
 impl Edit {
+    pub fn into_atoms(self) -> Vec<AtomEdit> {
+        self.atoms
+    }
+
     pub fn apply(&self, text: &str) -> String {
-        let mut text = text.to_owned();
+        let mut total_len = text.len();
         for atom in self.atoms.iter() {
-            text = atom.apply(&text);
+            total_len += atom.insert.len();
+            total_len -= atom.end() - atom.start();
         }
-        text
+        let mut buf = String::with_capacity(total_len);
+        let mut prev = 0;
+        for atom in self.atoms.iter() {
+            if atom.start() > prev {
+                buf.push_str(&text[prev..atom.start()]);
+            }
+            buf.push_str(&atom.insert);
+            prev = atom.end();
+        }
+        buf.push_str(&text[prev..text.len()]);
+        assert_eq!(buf.len(), total_len);
+        buf
     }
 }
 
 impl AtomEdit {
-    fn apply(&self, text: &str) -> String {
-        let prefix = &text[
-            TextRange::from_to(0.into(), self.delete.start())
-        ];
-        let suffix = &text[
-            TextRange::from_to(self.delete.end(), TextUnit::of_str(text))
-        ];
-        let mut res = String::with_capacity(prefix.len() + self.insert.len() + suffix.len());
-        res.push_str(prefix);
-        res.push_str(&self.insert);
-        res.push_str(suffix);
-        res
+    fn start(&self) -> usize {
+        u32::from(self.delete.start()) as usize
     }
 
-    fn apply_to_position(&self, pos: TextUnit) -> Option<TextUnit> {
-        if pos <= self.delete.start() {
-            return Some(pos);
-        }
-        if pos < self.delete.end() {
-            return None;
-        }
-        Some(pos - self.delete.len() + TextUnit::of_str(&self.insert))
-    }
-
-    fn apply_to_range(&self, range: TextRange) -> Option<TextRange> {
-        Some(TextRange::from_to(
-            self.apply_to_position(range.start())?,
-            self.apply_to_position(range.end())?,
-        ))
+    fn end(&self) -> usize {
+        u32::from(self.delete.end()) as usize
     }
 }
-
diff --git a/crates/libeditor/src/lib.rs b/crates/libeditor/src/lib.rs
index 103f32190..1e88f1471 100644
--- a/crates/libeditor/src/lib.rs
+++ b/crates/libeditor/src/lib.rs
@@ -19,7 +19,7 @@ pub use self::{
     line_index::{LineIndex, LineCol},
     extend_selection::extend_selection,
     symbols::{FileSymbol, file_symbols},
-    edit::{EditBuilder, Edit},
+    edit::{EditBuilder, Edit, AtomEdit},
     code_actions::{flip_comma},
 };
 
diff --git a/crates/server/Cargo.toml b/crates/server/Cargo.toml
index 2d0db2838..8e077ecf0 100644
--- a/crates/server/Cargo.toml
+++ b/crates/server/Cargo.toml
@@ -11,10 +11,11 @@ serde_derive = "1.0.71"
 drop_bomb = "0.1.0"
 crossbeam-channel = "0.2.4"
 threadpool = "1.7.1"
-flexi_logger = "0.9.0"
+flexi_logger = "0.9.1"
 log = "0.4.3"
 url_serde = "0.2.0"
 languageserver-types = "0.49.0"
+text_unit = { version = "0.1.2", features = ["serde"] }
 
 libsyntax2 = { path = "../libsyntax2" }
 libeditor = { path = "../libeditor" }
diff --git a/crates/server/src/caps.rs b/crates/server/src/caps.rs
index b502b0865..d06a43a82 100644
--- a/crates/server/src/caps.rs
+++ b/crates/server/src/caps.rs
@@ -3,34 +3,39 @@ use languageserver_types::{
     TextDocumentSyncCapability,
     TextDocumentSyncOptions,
     TextDocumentSyncKind,
+    ExecuteCommandOptions,
 };
 
-pub const SERVER_CAPABILITIES: ServerCapabilities = ServerCapabilities {
-    text_document_sync: Some(TextDocumentSyncCapability::Options(
-        TextDocumentSyncOptions {
-            open_close: Some(true),
-            change: Some(TextDocumentSyncKind::Full),
-            will_save: None,
-            will_save_wait_until: None,
-            save: None,
-        }
-    )),
-    hover_provider: None,
-    completion_provider: None,
-    signature_help_provider: None,
-    definition_provider: None,
-    type_definition_provider: None,
-    implementation_provider: None,
-    references_provider: None,
-    document_highlight_provider: None,
-    document_symbol_provider: Some(true),
-    workspace_symbol_provider: None,
-    code_action_provider: Some(true),
-    code_lens_provider: None,
-    document_formatting_provider: None,
-    document_range_formatting_provider: None,
-    document_on_type_formatting_provider: None,
-    rename_provider: None,
-    color_provider: None,
-    execute_command_provider: None,
-};
+pub fn server_capabilities() -> ServerCapabilities {
+    ServerCapabilities {
+        text_document_sync: Some(TextDocumentSyncCapability::Options(
+            TextDocumentSyncOptions {
+                open_close: Some(true),
+                change: Some(TextDocumentSyncKind::Full),
+                will_save: None,
+                will_save_wait_until: None,
+                save: None,
+            }
+        )),
+        hover_provider: None,
+        completion_provider: None,
+        signature_help_provider: None,
+        definition_provider: None,
+        type_definition_provider: None,
+        implementation_provider: None,
+        references_provider: None,
+        document_highlight_provider: None,
+        document_symbol_provider: Some(true),
+        workspace_symbol_provider: None,
+        code_action_provider: Some(true),
+        code_lens_provider: None,
+        document_formatting_provider: None,
+        document_range_formatting_provider: None,
+        document_on_type_formatting_provider: None,
+        rename_provider: None,
+        color_provider: None,
+        execute_command_provider: Some(ExecuteCommandOptions {
+            commands: vec!["apply_code_action".to_string()],
+        }),
+    }
+}
diff --git a/crates/server/src/conv.rs b/crates/server/src/conv.rs
index c7bea15df..0ed989b32 100644
--- a/crates/server/src/conv.rs
+++ b/crates/server/src/conv.rs
@@ -1,23 +1,23 @@
-use languageserver_types::{Range, SymbolKind, Position};
-use libeditor::{LineIndex, LineCol};
+use languageserver_types::{Range, SymbolKind, Position, TextEdit};
+use libeditor::{LineIndex, LineCol, Edit, AtomEdit};
 use libsyntax2::{SyntaxKind, TextUnit, TextRange};
 
 pub trait Conv {
     type Output;
-    fn conv(&self) -> Self::Output;
+    fn conv(self) -> Self::Output;
 }
 
 pub trait ConvWith {
     type Ctx;
     type Output;
-    fn conv_with(&self, ctx: &Self::Ctx) -> Self::Output;
+    fn conv_with(self, ctx: &Self::Ctx) -> Self::Output;
 }
 
 impl Conv for SyntaxKind {
     type Output = SymbolKind;
 
-    fn conv(&self) -> <Self as Conv>::Output {
-        match *self {
+    fn conv(self) -> <Self as Conv>::Output {
+        match self {
             SyntaxKind::FUNCTION => SymbolKind::Function,
             SyntaxKind::STRUCT => SymbolKind::Struct,
             SyntaxKind::ENUM => SymbolKind::Enum,
@@ -35,7 +35,7 @@ impl ConvWith for Position {
     type Ctx = LineIndex;
     type Output = TextUnit;
 
-    fn conv_with(&self, line_index: &LineIndex) -> TextUnit {
+    fn conv_with(self, line_index: &LineIndex) -> TextUnit {
         // TODO: UTF-16
         let line_col = LineCol {
             line: self.line as u32,
@@ -49,8 +49,8 @@ impl ConvWith for TextUnit {
     type Ctx = LineIndex;
     type Output = Position;
 
-    fn conv_with(&self, line_index: &LineIndex) -> Position {
-        let line_col = line_index.line_col(*self);
+    fn conv_with(self, line_index: &LineIndex) -> Position {
+        let line_col = line_index.line_col(self);
         // TODO: UTF-16
         Position::new(line_col.line as u64, u32::from(line_col.col) as u64)
     }
@@ -60,7 +60,7 @@ impl ConvWith for TextRange {
     type Ctx = LineIndex;
     type Output = Range;
 
-    fn conv_with(&self, line_index: &LineIndex) -> Range {
+    fn conv_with(self, line_index: &LineIndex) -> Range {
         Range::new(
             self.start().conv_with(line_index),
             self.end().conv_with(line_index),
@@ -72,10 +72,70 @@ impl ConvWith for Range {
     type Ctx = LineIndex;
     type Output = TextRange;
 
-    fn conv_with(&self, line_index: &LineIndex) -> TextRange {
+    fn conv_with(self, line_index: &LineIndex) -> TextRange {
         TextRange::from_to(
             self.start.conv_with(line_index),
             self.end.conv_with(line_index),
         )
     }
 }
+
+impl ConvWith for Edit {
+    type Ctx = LineIndex;
+    type Output = Vec<TextEdit>;
+
+    fn conv_with(self, line_index: &LineIndex) -> Vec<TextEdit> {
+        self.into_atoms()
+            .into_iter()
+            .map_conv_with(line_index)
+            .collect()
+    }
+}
+
+impl ConvWith for AtomEdit {
+    type Ctx = LineIndex;
+    type Output = TextEdit;
+
+    fn conv_with(self, line_index: &LineIndex) -> TextEdit {
+        TextEdit {
+            range: self.delete.conv_with(line_index),
+            new_text: self.insert,
+        }
+    }
+}
+
+
+pub trait MapConvWith<'a>: Sized {
+    type Ctx;
+    type Output;
+
+    fn map_conv_with(self, ctx: &'a Self::Ctx) -> ConvWithIter<'a, Self, Self::Ctx> {
+        ConvWithIter { iter: self, ctx }
+    }
+}
+
+impl<'a, I> MapConvWith<'a> for I
+    where I: Iterator,
+          I::Item: ConvWith
+{
+    type Ctx = <I::Item as ConvWith>::Ctx;
+    type Output = <I::Item as ConvWith>::Output;
+}
+
+pub struct ConvWithIter<'a, I, Ctx: 'a> {
+    iter: I,
+    ctx: &'a Ctx,
+}
+
+impl<'a, I, Ctx> Iterator for ConvWithIter<'a, I, Ctx>
+    where
+        I: Iterator,
+        I::Item: ConvWith<Ctx=Ctx>,
+{
+    type Item = <I::Item as ConvWith>::Output;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.iter.next().map(|item| item.conv_with(self.ctx))
+    }
+}
+
diff --git a/crates/server/src/dispatch.rs b/crates/server/src/dispatch.rs
index bfdbd30ca..3a3ee74bb 100644
--- a/crates/server/src/dispatch.rs
+++ b/crates/server/src/dispatch.rs
@@ -25,7 +25,7 @@ impl<R: ClientRequest> Responder<R> {
         let res = match result {
             Ok(result) => {
                 RawResponse {
-                    id: Some(self.id),
+                    id: self.id,
                     result: serde_json::to_value(result)?,
                     error: serde_json::Value::Null,
                 }
@@ -125,7 +125,7 @@ fn error_response(id: u64, code: ErrorCode, message: &'static str) -> Result<Raw
         message: &'static str,
     }
     let resp = RawResponse {
-        id: Some(id),
+        id,
         result: serde_json::Value::Null,
         error: serde_json::to_value(Error {
             code: code as i32,
diff --git a/crates/server/src/io.rs b/crates/server/src/io.rs
index 5eafc6942..f247327ab 100644
--- a/crates/server/src/io.rs
+++ b/crates/server/src/io.rs
@@ -34,8 +34,13 @@ pub struct RawNotification {
 
 #[derive(Debug, Serialize, Deserialize)]
 pub struct RawResponse {
-    pub id: Option<u64>,
+    // JSON RPC allows this to be null if it was impossible
+    // to decode the request's id. Ignore this special case
+    // and just die horribly.
+    pub id: u64,
+    #[serde(default)]
     pub result: Value,
+    #[serde(default)]
     pub error: Value,
 }
 
diff --git a/crates/server/src/main.rs b/crates/server/src/main.rs
index 7416de08a..c2952465e 100644
--- a/crates/server/src/main.rs
+++ b/crates/server/src/main.rs
@@ -27,7 +27,7 @@ mod main_loop;
 
 use threadpool::ThreadPool;
 use crossbeam_channel::bounded;
-use flexi_logger::Logger;
+use flexi_logger::{Logger, Duplicate};
 use libanalysis::WorldState;
 
 use ::{
@@ -38,6 +38,7 @@ pub type Result<T> = ::std::result::Result<T, ::failure::Error>;
 
 fn main() -> Result<()> {
     Logger::with_env()
+        .duplicate_to_stderr(Duplicate::All)
         .log_to_file()
         .directory("log")
         .start()?;
@@ -81,7 +82,7 @@ fn initialize(io: &mut Io) -> Result<()> {
         RawMsg::Request(req) => {
             let mut req = Some(req);
             dispatch::handle_request::<req::Initialize, _>(&mut req, |_params, resp| {
-                let res = req::InitializeResult { capabilities: caps::SERVER_CAPABILITIES };
+                let res = req::InitializeResult { capabilities: caps::server_capabilities() };
                 let resp = resp.into_response(Ok(res))?;
                 io.send(RawMsg::Response(resp));
                 Ok(())
diff --git a/crates/server/src/main_loop/handlers.rs b/crates/server/src/main_loop/handlers.rs
index c6db22289..d4ae2a368 100644
--- a/crates/server/src/main_loop/handlers.rs
+++ b/crates/server/src/main_loop/handlers.rs
@@ -1,15 +1,18 @@
+use std::collections::HashMap;
+
 use languageserver_types::{
     Diagnostic, DiagnosticSeverity, Url, DocumentSymbol,
-    Command
+    Command, TextDocumentIdentifier, WorkspaceEdit
 };
 use libanalysis::World;
 use libeditor;
-use serde_json::to_value;
+use libsyntax2::TextUnit;
+use serde_json::{to_value, from_value};
 
 use ::{
     req::{self, Decoration}, Result,
     util::FilePath,
-    conv::{Conv, ConvWith},
+    conv::{Conv, ConvWith, MapConvWith},
 };
 
 pub fn handle_syntax_tree(
@@ -29,9 +32,9 @@ pub fn handle_extend_selection(
     let file = world.file_syntax(&path)?;
     let line_index = world.file_line_index(&path)?;
     let selections = params.selections.into_iter()
-        .map(|r| r.conv_with(&line_index))
+        .map_conv_with(&line_index)
         .map(|r| libeditor::extend_selection(&file, r).unwrap_or(r))
-        .map(|r| r.conv_with(&line_index))
+        .map_conv_with(&line_index)
         .collect();
     Ok(req::ExtendSelectionResult { selections })
 }
@@ -78,18 +81,71 @@ pub fn handle_code_action(
     let line_index = world.file_line_index(&path)?;
     let offset = params.range.conv_with(&line_index).start();
     let ret = if libeditor::flip_comma(&file, offset).is_some() {
-        Some(vec![apply_code_action_cmd(ActionId::FlipComma)])
+        let cmd = apply_code_action_cmd(
+            ActionId::FlipComma,
+            params.text_document,
+            offset,
+        );
+        Some(vec![cmd])
     } else {
         None
     };
     Ok(ret)
 }
 
-fn apply_code_action_cmd(id: ActionId) -> Command {
+pub fn handle_execute_command(
+    world: World,
+    mut params: req::ExecuteCommandParams,
+) -> Result<req::ApplyWorkspaceEditParams> {
+    if params.command.as_str() != "apply_code_action" {
+        bail!("unknown cmd: {:?}", params.command);
+    }
+    if params.arguments.len() != 1 {
+        bail!("expected single arg, got {}", params.arguments.len());
+    }
+    let arg = params.arguments.pop().unwrap();
+    let arg: ActionRequest = from_value(arg)?;
+    match arg.id {
+        ActionId::FlipComma => {
+            let path = arg.text_document.file_path()?;
+            let file = world.file_syntax(&path)?;
+            let line_index = world.file_line_index(&path)?;
+            let edit = match libeditor::flip_comma(&file, arg.offset) {
+                Some(edit) => edit(),
+                None => bail!("command not applicable"),
+            };
+            let mut changes = HashMap::new();
+            changes.insert(
+                arg.text_document.uri,
+                edit.conv_with(&line_index),
+            );
+            let edit = WorkspaceEdit {
+                changes: Some(changes),
+                document_changes: None,
+            };
+
+            Ok(req::ApplyWorkspaceEditParams { edit })
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize)]
+struct ActionRequest {
+    id: ActionId,
+    text_document: TextDocumentIdentifier,
+    offset: TextUnit,
+}
+
+fn apply_code_action_cmd(id: ActionId, doc: TextDocumentIdentifier, offset: TextUnit) -> Command {
+    let action_request = ActionRequest {
+        id,
+        text_document: doc,
+        offset,
+    };
     Command {
         title: id.title().to_string(),
         command: "apply_code_action".to_string(),
-        arguments: Some(vec![to_value(id).unwrap()]),
+        arguments: Some(vec![to_value(action_request).unwrap()]),
     }
 }
 
diff --git a/crates/server/src/main_loop/mod.rs b/crates/server/src/main_loop/mod.rs
index 3d367f5f6..5b7093ad7 100644
--- a/crates/server/src/main_loop/mod.rs
+++ b/crates/server/src/main_loop/mod.rs
@@ -6,6 +6,7 @@ use threadpool::ThreadPool;
 use crossbeam_channel::{Sender, Receiver};
 use languageserver_types::Url;
 use libanalysis::{World, WorldState};
+use serde_json::to_value;
 
 use {
     req, dispatch,
@@ -19,6 +20,7 @@ use {
         publish_decorations,
         handle_document_symbol,
         handle_code_action,
+        handle_execute_command,
     },
 };
 
@@ -79,7 +81,9 @@ pub(super) fn main_loop(
                         on_notification(io, world, pool, &sender, not)?
                     }
                     RawMsg::Response(resp) => {
-                        error!("unexpected response: {:?}", resp)
+                        if !pending_requests.remove(&resp.id) {
+                            error!("unexpected response: {:?}", resp)
+                        }
                     }
                 }
             }
@@ -107,22 +111,30 @@ fn on_request(
     handle_request_on_threadpool::<req::CodeActionRequest>(
         &mut req, pool, world, sender, handle_code_action,
     )?;
-//    dispatch::handle_request::<req::ExecuteCommand, _>(&mut req, |(), resp| {
-//        let world = world.snapshot();
-//        let sender = sender.clone();
-//        pool.execute(move || {
-//            let task = match handle_execute_command(world, params) {
-//                Ok(req) => Task::Request(req),
-//                Err(e) => Task::Die(e),
-//            };
-//            sender.send(task)
-//        });
-//
-//        let resp = resp.into_response(Ok(()))?;
-//        io.send(RawMsg::Response(resp));
-//        shutdown = true;
-//        Ok(())
-//    })?;
+    dispatch::handle_request::<req::ExecuteCommand, _>(&mut req, |params, resp| {
+        io.send(RawMsg::Response(resp.into_response(Ok(None))?));
+
+        let world = world.snapshot();
+        let sender = sender.clone();
+        pool.execute(move || {
+            let task = match handle_execute_command(world, params) {
+                Ok(req) => match to_value(req) {
+                    Err(e) => Task::Die(e.into()),
+                    Ok(params) => {
+                        let request = RawRequest {
+                            id: 0,
+                            method: <req::ApplyWorkspaceEdit as req::ClientRequest>::METHOD.to_string(),
+                            params,
+                        };
+                        Task::Request(request)
+                    }
+                },
+                Err(e) => Task::Die(e),
+            };
+            sender.send(task)
+        });
+        Ok(())
+    })?;
 
     let mut shutdown = false;
     dispatch::handle_request::<req::Shutdown, _>(&mut req, |(), resp| {
diff --git a/crates/server/src/req.rs b/crates/server/src/req.rs
index e3b1cdf50..a22ba4bc3 100644
--- a/crates/server/src/req.rs
+++ b/crates/server/src/req.rs
@@ -6,7 +6,8 @@ pub use languageserver_types::{
     request::*, notification::*,
     InitializeResult, PublishDiagnosticsParams,
     DocumentSymbolParams, DocumentSymbolResponse,
-    CodeActionParams,
+    CodeActionParams, ApplyWorkspaceEditParams,
+    ExecuteCommandParams,
 };