feat(dap): implement Restart request (#5651)

Add a restart debug session command, which would issue a
[Restart Request][1], if the debugger supports it and a session is
running. It uses the same arguments and requests used to start the
initial session, when recreating it.

It builds upon #5532, making use of the changes to the termination
workflow of a session.

[1]: https://microsoft.github.io/debug-adapter-protocol/specification#Requests_Restart

Closes: #5594

Signed-off-by: Filip Dutescu <filip.dutescu@gmail.com>

5 files changed, 60 insertions, 2 deletions

diff --git a/helix-dap/src/client.rs b/helix-dap/src/client.rs
index f6d8a069..ff727d00 100644
--- a/helix-dap/src/client.rs
+++ b/helix-dap/src/client.rs
@@ -33,6 +33,7 @@ pub struct Client {
     server_tx: UnboundedSender<Payload>,
     request_counter: AtomicU64,
     connection_type: Option<ConnectionType>,
+    starting_request_args: Option<Value>,
     pub caps: Option<DebuggerCapabilities>,
     // thread_id -> frames
     pub stack_frames: HashMap<ThreadId, Vec<StackFrame>>,
@@ -87,6 +88,7 @@ impl Client {
             request_counter: AtomicU64::new(0),
             caps: None,
             connection_type: None,
+            starting_request_args: None,
             stack_frames: HashMap::new(),
             thread_states: HashMap::new(),
             thread_id: None,
@@ -158,6 +160,10 @@ impl Client {
         )
     }
 
+    pub fn starting_request_args(&self) -> &Option<Value> {
+        &self.starting_request_args
+    }
+
     pub async fn tcp_process(
         cmd: &str,
         args: Vec<&str>,
@@ -356,14 +362,25 @@ impl Client {
 
     pub fn launch(&mut self, args: serde_json::Value) -> impl Future<Output = Result<Value>> {
         self.connection_type = Some(ConnectionType::Launch);
+        self.starting_request_args = Some(args.clone());
         self.call::<requests::Launch>(args)
     }
 
     pub fn attach(&mut self, args: serde_json::Value) -> impl Future<Output = Result<Value>> {
         self.connection_type = Some(ConnectionType::Attach);
+        self.starting_request_args = Some(args.clone());
         self.call::<requests::Attach>(args)
     }
 
+    pub fn restart(&self) -> impl Future<Output = Result<Value>> {
+        let args = if let Some(args) = &self.starting_request_args {
+            args.clone()
+        } else {
+            Value::Null
+        };
+        self.call::<requests::Restart>(args)
+    }
+
     pub async fn set_breakpoints(
         &self,
         file: PathBuf,
diff --git a/helix-dap/src/types.rs b/helix-dap/src/types.rs
index c598790b..bbaf53a6 100644
--- a/helix-dap/src/types.rs
+++ b/helix-dap/src/types.rs
@@ -378,7 +378,7 @@ pub mod requests {
 
     impl Request for Launch {
         type Arguments = Value;
-        type Result = Value;
+        type Result = ();
         const COMMAND: &'static str = "launch";
     }
 
@@ -387,7 +387,7 @@ pub mod requests {
 
     impl Request for Attach {
         type Arguments = Value;
-        type Result = Value;
+        type Result = ();
         const COMMAND: &'static str = "attach";
     }
 
@@ -403,6 +403,15 @@ pub mod requests {
     }
 
     #[derive(Debug)]
+    pub enum Restart {}
+
+    impl Request for Restart {
+        type Arguments = Value;
+        type Result = ();
+        const COMMAND: &'static str = "restart";
+    }
+
+    #[derive(Debug)]
     pub enum Disconnect {}
 
     impl Request for Disconnect {
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index cd7626eb..c76e9f2b 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -430,6 +430,7 @@ impl MappableCommand {
         goto_next_paragraph, "Goto next paragraph",
         goto_prev_paragraph, "Goto previous paragraph",
         dap_launch, "Launch debug target",
+        dap_restart, "Restart debugging session",
         dap_toggle_breakpoint, "Toggle breakpoint",
         dap_continue, "Continue program execution",
         dap_pause, "Pause program execution",
diff --git a/helix-term/src/commands/dap.rs b/helix-term/src/commands/dap.rs
index 023ed377..dac1e9d5 100644
--- a/helix-term/src/commands/dap.rs
+++ b/helix-term/src/commands/dap.rs
@@ -289,6 +289,36 @@ pub fn dap_launch(cx: &mut Context) {
     ))));
 }
 
+pub fn dap_restart(cx: &mut Context) {
+    let debugger = match &cx.editor.debugger {
+        Some(debugger) => debugger,
+        None => {
+            cx.editor.set_error("Debugger is not running");
+            return;
+        }
+    };
+    if !debugger
+        .capabilities()
+        .supports_restart_request
+        .unwrap_or(false)
+    {
+        cx.editor
+            .set_error("Debugger does not support session restarts");
+        return;
+    }
+    if debugger.starting_request_args().is_none() {
+        cx.editor
+            .set_error("No arguments found with which to restart the sessions");
+        return;
+    }
+
+    dap_callback(
+        cx.jobs,
+        debugger.restart(),
+        |editor, _compositor, _resp: ()| editor.set_status("Debugging session restarted"),
+    );
+}
+
 fn debug_parameter_prompt(
     completions: Vec<DebugConfigCompletion>,
     config_name: String,
diff --git a/helix-term/src/keymap/default.rs b/helix-term/src/keymap/default.rs
index 7425c815..9bd00280 100644
--- a/helix-term/src/keymap/default.rs
+++ b/helix-term/src/keymap/default.rs
@@ -223,6 +223,7 @@ pub fn default() -> HashMap<Mode, Keymap> {
             "'" => last_picker,
             "g" => { "Debug (experimental)" sticky=true
                 "l" => dap_launch,
+                "r" => dap_restart,
                 "b" => dap_toggle_breakpoint,
                 "c" => dap_continue,
                 "h" => dap_pause,