Allow starting debug server without opening apps

Author: amomchilov

lib/debug/config.rb

@@ -324,7 +324,7 @@ def self.parse_argv argv
           when 'tcp'
             config[:open] = true
             config[:port] ||= 0
-          when 'vscode', 'chrome', 'cdp'
+          when 'vscode', 'dap', 'chrome', 'cdp'
             config[:open] = f&.downcase
           else
             raise "Unknown option for --open: #{f}"

lib/debug/server.rb

@@ -376,9 +376,9 @@ def after_fork_parent
       # do nothing
     end
 
-    def vscode_setup debug_port
+    def vscode_setup debug_port, launch_vscode: true
       require_relative 'server_dap'
-      UI_DAP.setup debug_port
+      UI_DAP.setup debug_port if launch_vscode
     end
   end
 
@@ -442,8 +442,10 @@ def accept
           case CONFIG[:open]
           when 'chrome'
             chrome_setup
+          when 'dap-server' # Start in Debug Adapter Protocol mode without launching Visual Studio Code
+            vscode_setup @local_addr.inspect_sockaddr, launch_vscode: false
           when 'vscode'
-            vscode_setup @local_addr.inspect_sockaddr
+            vscode_setup @local_addr.inspect_sockaddr, launch_vscode: true
           end
 
           Socket.accept_loop(socks) do |sock, client|
@@ -496,7 +498,12 @@ def accept
       end
 
       ::DEBUGGER__.warn "Debugger can attach via UNIX domain socket (#{@sock_path})"
-      vscode_setup @sock_path if CONFIG[:open] == 'vscode'
+      case CONFIG[:open]
+      when 'dap-server' # Start in Debug Adapter Protocol mode without launching Visual Studio Code
+        vscode_setup @sock_path, launch_vscode: false
+      when 'vscode'
+        vscode_setup @sock_path, launch_vscode: true
+      end
 
       begin
         Socket.unix_server_loop @sock_path do |sock, client|

lib/debug/session.rb

@@ -1118,9 +1118,15 @@ def register_default_command
         when 'vscode'
           CONFIG[:open] = 'vscode'
           ::DEBUGGER__.open nonstop: true
-        when 'chrome', 'cdp'
+        when 'dap'
+          CONFIG[:open] = 'dap'
+          ::DEBUGGER__.open nonstop: true
+        when 'chrome'
           CONFIG[:open] = 'chrome'
           ::DEBUGGER__.open_tcp host: CONFIG[:host], port: (CONFIG[:port] || 0), nonstop: true
+        when 'cdp'
+          CONFIG[:open] = 'cdp'
+          ::DEBUGGER__.open_tcp host: CONFIG[:host], port: (CONFIG[:port] || 0), nonstop: true
         else
           raise "Unknown arg: #{arg}"
         end