1 files changed, 103 insertions, 0 deletions
diff --git a/lib/irb/debug/ui.rb b/lib/irb/debug/ui.rb
new file mode 100644
index 0000000000..307097b8c9
--- /dev/null
+++ b/lib/irb/debug/ui.rb
@@ -0,0 +1,103 @@
+require 'io/console/size'
+require 'debug/console'
+
+module IRB
+  module Debug
+    class UI < DEBUGGER__::UI_Base
+      def initialize(irb)
+        @irb = irb
+      end
+
+      def remote?
+        false
+      end
+
+      def activate session, on_fork: false
+      end
+
+      def deactivate
+      end
+
+      def width
+        if (w = IO.console_size[1]) == 0 # for tests PTY
+          80
+        else
+          w
+        end
+      end
+
+      def quit n
+        yield
+        exit n
+      end
+
+      def ask prompt
+        setup_interrupt do
+          print prompt
+          ($stdin.gets || '').strip
+        end
+      end
+
+      def puts str = nil
+        case str
+        when Array
+          str.each{|line|
+            $stdout.puts line.chomp
+          }
+        when String
+          str.each_line{|line|
+            $stdout.puts line.chomp
+          }
+        when nil
+          $stdout.puts
+        end
+      end
+
+      def readline _
+        setup_interrupt do
+          tc = DEBUGGER__::SESSION.instance_variable_get(:@tc)
+          cmd = @irb.debug_readline(tc.current_frame.binding || TOPLEVEL_BINDING)
+
+          case cmd
+          when nil # when user types C-d
+            "continue"
+          else
+            cmd
+          end
+        end
+      end
+
+      def setup_interrupt
+        DEBUGGER__::SESSION.intercept_trap_sigint false do
+          current_thread = Thread.current # should be session_server thread
+
+          prev_handler = trap(:INT){
+            current_thread.raise Interrupt
+          }
+
+          yield
+        ensure
+          trap(:INT, prev_handler)
+        end
+      end
+
+      def after_fork_parent
+        parent_pid = Process.pid
+
+        at_exit{
+          DEBUGGER__::SESSION.intercept_trap_sigint_end
+          trap(:SIGINT, :IGNORE)
+
+          if Process.pid == parent_pid
+            # only check child process from its parent
+            begin
+              # wait for all child processes to keep terminal
+              Process.waitpid
+            rescue Errno::ESRCH, Errno::ECHILD
+            end
+          end
+        }
+      end
+    end
+  end
+end