gem-rdoc-no-overwrite-option

Index: lib/rubygems/doc_manager.rb
===================================================================
--- lib/rubygems/doc_manager.rb	(revision 2210)
+++ lib/rubygems/doc_manager.rb	(working copy)
@@ -98,6 +98,13 @@ class Gem::DocManager
   end
 
   ##
+  # Is the RI documentation installed?
+
+  def ri_installed?
+    File.exist?(File.join(@doc_dir, "ri"))
+  end
+
+  ##
   # Generate the RI documents for this gem spec.
   #
   # Note that if both RI and RDoc documents are generated from the same
Index: lib/rubygems/commands/rdoc_command.rb
===================================================================
--- lib/rubygems/commands/rdoc_command.rb	(revision 2210)
+++ lib/rubygems/commands/rdoc_command.rb	(working copy)
@@ -8,7 +8,7 @@ class Gem::Commands::RdocCommand < Gem::
   def initialize
     super 'rdoc', 'Generates RDoc for pre-installed gems',
           :version => Gem::Requirement.default,
-          :include_rdoc => true, :include_ri => true
+          :include_rdoc => true, :include_ri => true, :overwrite => true
 
     add_option('--all',
                'Generate RDoc/RI documentation for all',
@@ -21,11 +21,21 @@ class Gem::Commands::RdocCommand < Gem::
       options[:include_rdoc] = value
     end
 
+    add_option('--[no-]rdoc',
+               'Include RDoc generated documents') do |value, options|
+      options[:include_rdoc] = value
+    end
+
     add_option('--[no-]ri',
                'Include RI generated documents') do |value, options|
       options[:include_ri] = value
     end
 
+    add_option('--[no-]overwrite',
+               'Overwrite installed documents') do |value, options|
+      options[:overwrite] = value
+    end
+
     add_version_option
   end
 
@@ -58,7 +68,8 @@ class Gem::Commands::RdocCommand < Gem::
 
     if options[:include_ri]
       specs.each do |spec|
-        Gem::DocManager.new(spec).generate_ri
+        doc = Gem::DocManager.new(spec)
+        doc.generate_ri if options[:overwrite] || !doc.ri_installed?
       end
 
       Gem::DocManager.update_ri_cache
@@ -66,7 +77,8 @@ class Gem::Commands::RdocCommand < Gem::
 
     if options[:include_rdoc]
       specs.each do |spec|
-        Gem::DocManager.new(spec).generate_rdoc
+        doc = Gem::DocManager.new(spec)
+        doc.generate_rdoc if options[:overwrite] || !doc.rdoc_installed?
       end
     end