Proposal: Refactor server_dap to use command-registration style

lib/debug/server_dap.rb

@@ -8,6 +8,7 @@
 module DEBUGGER__
   module UI_DAP
     SHOW_PROTOCOL = ENV['DEBUG_DAP_SHOW_PROTOCOL'] == '1' || ENV['RUBY_DEBUG_DAP_SHOW_PROTOCOL'] == '1'
+    REGISTERED_REQUESTS = {}
 
     def self.setup debug_port
       if File.directory? '.vscode'
@@ -64,6 +65,12 @@ def self.setup debug_port
       end
     end
 
+    def self.register_request *names, &b
+      names.each{|name|
+        REGISTERED_REQUESTS[name] = b
+      }
+    end
+
     def show_protocol dir, msg
       if SHOW_PROTOCOL
         $stderr.puts "\##{Process.pid}:[#{dir}] #{msg}"
@@ -274,21 +281,15 @@ def recv_request
       retry
     end
 
-    def process
-      while req = recv_request
-        raise "not a request: #{req.inspect}" unless req['type'] == 'request'
-        args = req.dig('arguments')
-
-        case req['command']
-
     ## boot/configuration
-        when 'launch'
+    register_request 'launch' do |req|
       send_response req
       # `launch` runs on debuggee on the same file system
       UI_DAP.local_fs_map_set req.dig('arguments', 'localfs') || req.dig('arguments', 'localfsMap') || true
       @nonstop = true
+    end
 
-        when 'attach'
+    register_request 'attach' do |req|
       send_response req
       UI_DAP.local_fs_map_set req.dig('arguments', 'localfs') || req.dig('arguments', 'localfsMap')
 
@@ -297,8 +298,9 @@ def process
       else
         @nonstop = false
       end
+    end
 
-        when 'configurationDone'
+    register_request 'configurationDone' do |req|
       send_response req
 
       if @nonstop
@@ -310,8 +312,9 @@ def process
                                 allThreadsStopped: true
         end
       end
+    end
 
-        when 'setBreakpoints'
+    register_request 'setBreakpoints' do |req, args|
       req_path = args.dig('source', 'path')
       path = UI_DAP.local_to_remote_path(req_path)
 
@@ -331,11 +334,13 @@ def process
       else
         send_response req, success: false, message: "#{req_path} is not available"
       end
+    end
 
-        when 'setFunctionBreakpoints'
+    register_request 'setFunctionBreakpoints' do |req|
       send_response req
+    end
 
-        when 'setExceptionBreakpoints'
+    register_request 'setExceptionBreakpoints' do |req, args|
       process_filter = ->(filter_id, cond = nil) {
         bp =
           case filter_id
@@ -363,8 +368,9 @@ def process
       }
 
       send_response req, breakpoints: filters
+    end
 
-        when 'disconnect'
+    register_request('disconnect') do |req, args|
       terminate = args.fetch("terminateDebuggee", false)
 
       SESSION.clear_all_breakpoints
@@ -382,12 +388,15 @@ def process
           pause
         end
       end
+    end
 
     ## control
-        when 'continue'
+    register_request 'continue' do |req|
       @q_msg << 'c'
       send_response req, allThreadsContinued: true
-        when 'next'
+    end
+
+    register_request 'next' do |req|
       begin
         @session.check_postmortem
         @q_msg << 'n'
@@ -397,7 +406,9 @@ def process
                       success: false, message: 'postmortem mode',
                       result: "'Next' is not supported while postmortem mode"
       end
-        when 'stepIn'
+    end
+
+    register_request 'stepIn' do |req|
       begin
         @session.check_postmortem
         @q_msg << 's'
@@ -407,7 +418,9 @@ def process
                       success: false, message: 'postmortem mode',
                       result: "'stepIn' is not supported while postmortem mode"
       end
-        when 'stepOut'
+    end
+
+    register_request 'stepOut' do |req|
       begin
         @session.check_postmortem
         @q_msg << 'fin'
@@ -417,28 +430,38 @@ def process
                       success: false, message: 'postmortem mode',
                       result: "'stepOut' is not supported while postmortem mode"
       end
-        when 'terminate'
+    end
+
+    register_request 'terminate' do |req|
       send_response req
       exit
-        when 'pause'
+    end
+
+    register_request 'pause' do |req|
       send_response req
       Process.kill(UI_ServerBase::TRAP_SIGNAL, Process.pid)
-        when 'reverseContinue'
+    end
+
+    register_request 'reverseContinue' do |req|
       send_response req,
                     success: false, message: 'cancelled',
                     result: "Reverse Continue is not supported. Only \"Step back\" is supported."
-        when 'stepBack'
+    end
+
+    register_request 'stepBack' do |req|
       @q_msg << req
+    end
 
     ## query
-        when 'threads'
+    register_request 'threads' do |req|
       send_response req, threads: SESSION.managed_thread_clients.map{|tc|
         { id: tc.id,
           name: tc.name,
         }
       }
+    end
 
-        when 'evaluate'
+    register_request 'evaluate' do |req|
       expr = req.dig('arguments', 'expression')
       if /\A\s*,(.+)\z/ =~ expr
         dbg_expr = $1
@@ -449,13 +472,23 @@ def process
       else
         @q_msg << req
       end
-        when 'stackTrace',
+    end
+
+    register_request 'stackTrace',
                       'scopes',
                       'variables',
                       'source',
-             'completions'
+                      'completions' do |req|
       @q_msg << req
+    end
+
+    def process
+      while req = recv_request
+        raise "not a request: #{req.inspect}" unless req['type'] == 'request'
+        args = req.dig('arguments')
 
+        if (cmd = REGISTERED_REQUESTS[req['command']])
+          self.instance_exec(req, args, &cmd)
         else
           if respond_to? mid = "request_#{req['command']}"
             __send__ mid, req