From d42d509eb107d2285a3d7f052238176a3a2861ae Mon Sep 17 00:00:00 2001
From: Hiroyuki Sano <sh19910711@gmail.com>
Date: Tue, 12 Jul 2016 07:30:42 +0000
Subject: [PATCH] Add Session#context(obj) method

---
 lib/web_console.rb               |  1 +
 lib/web_console/context.rb       | 46 ++++++++++++++++++++++++++++++++
 lib/web_console/middleware.rb    |  2 +-
 lib/web_console/session.rb       |  9 +++++--
 test/web_console/context_test.rb | 28 +++++++++++++++++++
 5 files changed, 83 insertions(+), 3 deletions(-)
 create mode 100644 lib/web_console/context.rb
 create mode 100644 test/web_console/context_test.rb

diff --git a/lib/web_console.rb b/lib/web_console.rb
index c1c549df..832bfb74 100644
--- a/lib/web_console.rb
+++ b/lib/web_console.rb
@@ -15,6 +15,7 @@ module WebConsole
   autoload :Whitelist
   autoload :Template
   autoload :Middleware
+  autoload :Context
 
   autoload_at 'web_console/errors' do
     autoload :Error
diff --git a/lib/web_console/context.rb b/lib/web_console/context.rb
new file mode 100644
index 00000000..b2249649
--- /dev/null
+++ b/lib/web_console/context.rb
@@ -0,0 +1,46 @@
+module WebConsole
+  # A context lets you get object names related to the current session binding.
+  class Context
+    def initialize(binding)
+      @binding = binding
+    end
+
+    # Extracts entire objects which can be called by the current session unless the objpath is present.
+    # Otherwise, it extracts methods and constants of the object specified by the objpath.
+    def extract(objpath)
+      if objpath.present?
+        local(objpath)
+      else
+        global
+      end
+    end
+
+    private
+
+      GLOBAL_OBJECTS = [
+        'global_variables',
+        'local_variables',
+        'instance_variables',
+        'instance_methods',
+        'class_variables',
+        'methods',
+        'Object.constants',
+        'Kernel.methods',
+      ]
+
+      def global
+        GLOBAL_OBJECTS.map { |cmd| eval(cmd) }.flatten
+      end
+
+      def local(objpath)
+        [
+          eval("#{objpath}.methods").map { |m| "#{objpath}.#{m}" },
+          eval("#{objpath}.constants").map { |c| "#{objpath}::#{c}" },
+        ].flatten
+      end
+
+      def eval(cmd)
+        @binding.eval(cmd) rescue []
+      end
+  end
+end
diff --git a/lib/web_console/middleware.rb b/lib/web_console/middleware.rb
index d0c36006..632eec71 100644
--- a/lib/web_console/middleware.rb
+++ b/lib/web_console/middleware.rb
@@ -103,7 +103,7 @@ def id_for_repl_session_stack_frame_change(request)
 
       def update_repl_session(id, request)
         json_response_with_session(id, request) do |session|
-          { output: session.eval(request.params[:input]) }
+          { output: session.eval(request.params[:input]), context: session.context(request.params[:context]) }
         end
       end
 
diff --git a/lib/web_console/session.rb b/lib/web_console/session.rb
index bf88e8cc..f6accd80 100644
--- a/lib/web_console/session.rb
+++ b/lib/web_console/session.rb
@@ -43,7 +43,7 @@ def from(storage)
     def initialize(bindings)
       @id = SecureRandom.hex(16)
       @bindings = bindings
-      @evaluator = Evaluator.new(bindings.first)
+      @evaluator = Evaluator.new(@current_binding = bindings.first)
 
       store_into_memory
     end
@@ -59,7 +59,12 @@ def eval(input)
     #
     # Returns nothing.
     def switch_binding_to(index)
-      @evaluator = Evaluator.new(@bindings[index.to_i])
+      @evaluator = Evaluator.new(@current_binding = @bindings[index.to_i])
+    end
+
+    # Returns context of the current binding
+    def context(objpath)
+      Context.new(@current_binding).extract(objpath)
     end
 
     private
diff --git a/test/web_console/context_test.rb b/test/web_console/context_test.rb
new file mode 100644
index 00000000..555366ed
--- /dev/null
+++ b/test/web_console/context_test.rb
@@ -0,0 +1,28 @@
+require 'test_helper'
+
+module WebConsole
+  class ContextTest < ActiveSupport::TestCase
+    test '#extract(empty) includes local variables' do
+      local_var = 'local'
+      assert Context.new(binding).extract('').include?(:local_var)
+    end
+
+    test '#extract(empty) includes instance variables' do
+      @instance_var = 'instance'
+      assert Context.new(binding).extract('').include?(:@instance_var)
+    end
+
+    test '#extract(empty) includes global variables' do
+      $global_var = 'global'
+      assert Context.new(binding).extract('').include?(:$global_var)
+    end
+
+    test '#extract(obj) returns methods' do
+      assert Context.new(binding).extract('Rails').include?('Rails.root')
+    end
+
+    test '#extract(obj) returns constants' do
+      assert Context.new(binding).extract('WebConsole').include?('WebConsole::Middleware')
+    end
+  end
+end