Allow listeners to return true to remove the listener

doc/dap.txt

@@ -1307,6 +1307,9 @@ For events, the listeners are called with two arguments:
 2. The event payload
 
 
+Both command and event listeners can return a boolean `true` to remove the
+registered listener.
+
 ==============================================================================
 BUILT-IN CLIENT EVENTS                                     *dap-listeners-ext*
 

lua/dap.lua

@@ -56,66 +56,69 @@ M.repl = setmetatable({}, {
   end
 })
 
+---@alias dap.RequestListener<T, U> fun(session: dap.Session, err: dap.ErrorResponse?, response: T, args: U, seq: number):boolean?
+
+---@alias dap.EventListener<T> fun(session: dap.Session, body: T):boolean?
 
 ---@class dap.listeners
----@field event_breakpoint table<string, fun(session: dap.Session, body: any)>
----@field event_capabilities table<string, fun(session: dap.Session, body: any)>
----@field event_continued table<string, fun(session: dap.Session, body: any)>
----@field event_exited table<string, fun(session: dap.Session, body: any)>
----@field event_initialized table<string, fun(session: dap.Session, body: any)>
----@field event_invalidated table<string, fun(session: dap.Session, body: any)>
----@field event_loadedSource table<string, fun(session: dap.Session, body: any)>
----@field event_memory table<string, fun(session: dap.Session, body: any)>
----@field event_module table<string, fun(session: dap.Session, body: any)>
----@field event_output table<string, fun(session: dap.Session, body: any)>
----@field event_process table<string, fun(session: dap.Session, body: any)>
----@field event_progressEnd table<string, fun(session: dap.Session, body: dap.ProgressEndEvent)>
----@field event_progressStart table<string, fun(session: dap.Session, body: dap.ProgressStartEvent)>
----@field event_progressUpdate table<string, fun(session: dap.Session, body: dap.ProgressUpdateEvent)>
----@field event_stopped table<string, fun(session: dap.Session, body: dap.StoppedEvent)>
----@field event_terminated table<string, fun(session: dap.Session, body: dap.TerminatedEvent)>
----@field event_thread table<string, fun(session: dap.Session, body: any)>
----@field attach table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field breakpointLocations table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field completions table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field configurationDone table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field continue table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field dataBreakpointInfo table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field disassemble table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field disconnect table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field evaluate table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field exceptionInfo table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field goto table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field gotoTargets table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field initialize table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field launch table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field loadedSources table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field modules table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field next table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field pause table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field readMemory table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field restart table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field restartFrame table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field reverseContinue table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field scopes table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setBreakpoints table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setDataBreakpoints table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setExceptionBreakpoints table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setExpression table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setFunctionBreakpoints table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setInstructionBreakpoints table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field setVariable table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field source table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field stackTrace table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field stepBack table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field stepIn table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field stepInTargets table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field stepOut table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field terminate table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field terminateThreads table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field threads table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field variables table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
----@field writeMemory table<string, fun(session: dap.Session, err: any, body: any, request: any, seq: number)>
+---@field event_breakpoint table<string, dap.EventListener<dap.BreakpointEvent>>
+---@field event_capabilities table<string, dap.EventListener<any>>
+---@field event_continued table<string, dap.EventListener<dap.ContinuedEvent>>
+---@field event_exited table<string, dap.EventListener<any>>
+---@field event_initialized table<string, dap.EventListener<dap.InitializedEvent>>
+---@field event_invalidated table<string, dap.EventListener<any>>
+---@field event_loadedSource table<string, dap.EventListener<any>>
+---@field event_memory table<string, dap.EventListener<any>>
+---@field event_module table<string, dap.EventListener<any>>
+---@field event_output table<string, dap.EventListener<dap.OutputEvent>>
+---@field event_process table<string, dap.EventListener<any>>
+---@field event_progressEnd table<string, dap.EventListener<dap.ProgressEndEvent>>
+---@field event_progressStart table<string, dap.EventListener<dap.ProgressStartEvent>>
+---@field event_progressUpdate table<string, dap.EventListener<dap.ProgressUpdateEvent>>
+---@field event_stopped table<string, dap.EventListener<dap.StoppedEvent>>
+---@field event_terminated table<string, dap.EventListener<dap.TerminatedEvent>>
+---@field event_thread table<string, dap.EventListener<dap.ThreadEvent>>
+---@field attach table<string, dap.RequestListener>
+---@field breakpointLocations table<string, dap.RequestListener>
+---@field completions table<string, dap.RequestListener<dap.CompletionsResponse, dap.CompletionsArguments>>
+---@field configurationDone table<string, dap.RequestListener>
+---@field continue table<string, dap.RequestListener>
+---@field dataBreakpointInfo table<string, dap.RequestListener>
+---@field disassemble table<string, dap.RequestListener>
+---@field disconnect table<string, dap.RequestListener<any, dap.DisconnectArguments>>
+---@field evaluate table<string, dap.RequestListener<dap.EvaluateResponse, dap.EvaluateArguments>>
+---@field exceptionInfo table<string, dap.RequestListener>
+---@field goto table<string, dap.RequestListener>
+---@field gotoTargets table<string, dap.RequestListener>
+---@field initialize table<string, dap.RequestListener>
+---@field launch table<string, dap.RequestListener>
+---@field loadedSources table<string, dap.RequestListener>
+---@field modules table<string, dap.RequestListener>
+---@field next table<string, dap.RequestListener>
+---@field pause table<string, dap.RequestListener>
+---@field readMemory table<string, dap.RequestListener>
+---@field restart table<string, dap.RequestListener>
+---@field restartFrame table<string, dap.RequestListener>
+---@field reverseContinue table<string, dap.RequestListener>
+---@field scopes table<string, dap.RequestListener>
+---@field setBreakpoints table<string, dap.RequestListener>
+---@field setDataBreakpoints table<string, dap.RequestListener>
+---@field setExceptionBreakpoints table<string, dap.RequestListener>
+---@field setExpression table<string, dap.RequestListener>
+---@field setFunctionBreakpoints table<string, dap.RequestListener>
+---@field setInstructionBreakpoints table<string, dap.RequestListener>
+---@field setVariable table<string, dap.RequestListener>
+---@field source table<string, dap.RequestListener>
+---@field stackTrace table<string, dap.RequestListener>
+---@field stepBack table<string, dap.RequestListener>
+---@field stepIn table<string, dap.RequestListener>
+---@field stepInTargets table<string, dap.RequestListener>
+---@field stepOut table<string, dap.RequestListener>
+---@field terminate table<string, dap.RequestListener>
+---@field terminateThreads table<string, dap.RequestListener>
+---@field threads table<string, dap.RequestListener>
+---@field variables table<string, dap.RequestListener<dap.VariableResponse, dap.VariablesArguments>>
+---@field writeMemory table<string, dap.RequestListener>
 
 
 M.listeners = {

lua/dap/protocol.lua

@@ -297,6 +297,7 @@
 ---@field instructionReference? string
 ---@field offset? number
 
+---@class dap.InitializedEvent
 
 ---@class dap.StoppedEvent
 ---@field reason "step"|"breakpoint"|"exception"|"pause"|"entry"|"goto"|"function breakpoint"|"data breakpoint"|"instruction breakpoint"|string;

lua/dap/session.lua

@@ -1048,6 +1048,17 @@ function Session:set_exception_breakpoints(filters, exceptionOptions, on_done)
 end
 
 
+---@param listeners table<string, dap.RequestListener<any>|dap.EventListener<any>>
+local function process_listener(listeners, ...)
+  for key, listener in pairs(listeners) do
+    local remove = listener(...)
+    if remove then
+      listeners[key] = nil
+    end
+  end
+end
+
+
 function Session:handle_body(body)
   local decoded = assert(json_decode(body), "Debug adapter must send JSON objects")
   log:debug(self.id, decoded)
@@ -1061,49 +1072,36 @@ function Session:handle_body(body)
       log:error('No callback found. Did the debug adapter send duplicate responses?', decoded)
       return
     end
+    local err = nil
+    local response = nil
     if decoded.success then
-      vim.schedule(function()
-        for _, c in pairs(listeners.before[decoded.command]) do
-          c(self, nil, decoded.body, request, decoded.request_seq)
-        end
-        callback(nil, decoded.body, decoded.request_seq)
-        for _, c in pairs(listeners.after[decoded.command]) do
-          c(self, nil, decoded.body, request, decoded.request_seq)
-        end
-      end)
+      response = decoded.body
     else
-      vim.schedule(function()
-        local err = {
-          message = decoded.message,
-          body = decoded.body,
-        }
-        setmetatable(err, err_mt)
-        for _, c in pairs(listeners.before[decoded.command]) do
-          c(self, err, nil, request, decoded.request_seq)
-        end
-        callback(err, nil, decoded.request_seq)
-        for _, c in pairs(listeners.after[decoded.command]) do
-          c(self, err, nil, request, decoded.request_seq)
-        end
-      end)
+      err = {
+        message = decoded.message,
+        body = decoded.body,
+      }
+      setmetatable(err, err_mt)
     end
+    vim.schedule(function()
+      local before = listeners.before[decoded.command]
+      process_listener(before, self, err, response, request, decoded.request_seq)
+      callback(err, decoded.body, decoded.request_seq)
+      local after = listeners.after[decoded.command]
+      process_listener(after, self, err, response, request, decoded.request_seq)
+    end)
   elseif decoded.event then
-    local callback = self['event_' .. decoded.event]
+    local callback_name = "event_" .. decoded.event
+    local callback = self[callback_name]
     vim.schedule(function()
-      local event_handled = false
-      for _, c in pairs(listeners.before['event_' .. decoded.event]) do
-        event_handled = true
-        c(self, decoded.body)
-      end
+      local before = listeners.before[callback_name]
+      process_listener(before, self, decoded.body)
       if callback then
-        event_handled = true
         callback(self, decoded.body)
       end
-      for _, c in pairs(listeners.after['event_' .. decoded.event]) do
-        event_handled = true
-        c(self, decoded.body)
-      end
-      if not event_handled then
+      local after = listeners.after[callback_name]
+      process_listener(after, self, decoded.body)
+      if not callback and not next(before) and not next(after) then
         log:warn('No event handler for ', decoded)
       end
     end)