Support ls command from irb

README.md

@@ -441,6 +441,10 @@ The `<...>` notation means the argument.
   * Show predecessor lines as opposed to the `list` command.
 * `l[ist] <start>` or `l[ist] <start>-<end>`
   * Show current frame's source code from the line <start> to <end> if given.
+* `ls`
+  * Executes `irb`'s `ls` command with current binding.
+* `ls <obj>`
+  * Executes `irb`'s `ls` command with the given obj.
 * `edit`
   * Open the current file on the editor (use `EDITOR` environment variable).
   * Note that edited file will not be reloaded.

lib/debug/session.rb

@@ -481,6 +481,17 @@ def process_command line
           return :retry
         end
 
+      # * `ls`
+      #   * Executes `irb`'s `ls` command with current binding.
+      # * `ls <obj>`
+      #   * Executes `irb`'s `ls` command with the given obj.
+      when 'ls'
+        if @ui.remote?
+          @ui.puts "not supported on the remote console."
+          return :retry
+        end
+        @tc << [:irb, :ls, arg]
+
       # * `edit`
       #   * Open the current file on the editor (use `EDITOR` environment variable).
       #   * Note that edited file will not be reloaded.

lib/debug/thread_client.rb

@@ -2,6 +2,7 @@
 
 require 'objspace'
 require 'pp'
+require "irb"
 
 require_relative 'frame_info'
 require_relative 'color'
@@ -15,6 +16,7 @@ def self.current
       end
     end
 
+    extend IRB::ExtendCommandBundle
     include Color
 
     attr_reader :location, :thread, :mode, :id
@@ -579,6 +581,26 @@ def wait_next_action
           else
             raise "unsupported frame operation: #{arg.inspect}"
           end
+          event! :result, nil
+        when :irb
+          cmd, arg_expr = *args
+
+          raise "unsupported irb command: #{cmd}" unless cmd == :ls
+
+          begin
+            # most irb commands require irb workplace or irb session present in the environment to work
+            init_irb_context
+
+            if arg_expr
+              arg = frame_eval(arg_expr)
+              self.class.send("irb_#{cmd}", arg)
+            else
+              self.class.send("irb_#{cmd}")
+            end
+          ensure
+            reset_irb_context
+          end
+
           event! :result, nil
         when :show
           type = args.shift
@@ -658,5 +680,16 @@ def to_s
       str += " (not under control)" unless self.mode
       str
     end
+
+    def init_irb_context
+      IRB.init_config(nil)
+      workspace = IRB::WorkSpace.new(current_frame.binding)
+      irb = IRB::Irb.new(workspace, nil)
+      IRB.conf[:MAIN_CONTEXT] = irb.context
+    end
+
+    def reset_irb_context
+      IRB.conf[:MAIN_CONTEXT] = nil
+    end
   end
 end

test/debug/ls_test.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+require_relative '../support/test_case'
+
+module DEBUGGER__
+  class LsTest < TestCase
+    def program
+      <<~RUBY
+     1| class Foo
+     2|   def initialize
+     3|     @var = "foobar"
+     4|   end
+     5|
+     6|   def bar; end
+     7|   def self.baz; end
+     8| end
+     9|
+    10| foo = Foo.new
+    11|
+    12| binding.b
+      RUBY
+    end
+
+    def test_ls_lists_local_variables
+      debug_code(program, remote: false) do
+        type 'c'
+        type 'ls'
+        assert_line_text(/locals.*: _  foo/)
+        type 'c'
+      end
+    end
+
+    def test_ls_lists_object_info
+      debug_code(program, remote: false) do
+        type 'c'
+        type 'ls foo'
+        assert_line_text([
+          /Foo#methods.*: bar/,
+          /instance variables.*: @var/
+        ])
+        type 'c'
+      end
+    end
+
+    def test_ls_lists_class_info
+      debug_code(program, remote: false) do
+        type 'c'
+        type 'ls Foo'
+        assert_line_text(
+          [
+            /Class#methods.*: allocate/,
+            /Foo\.methods.*: baz/,
+          ]
+        )
+        type 'c'
+      end
+    end
+  end
+end