Add support for meta tags

Rakefile

@@ -25,6 +25,10 @@ RDoc::Task.new do |doc|
   doc.title = "rdoc #{RDoc::VERSION} Documentation"
   doc.rdoc_dir = '_site' # for github pages
   doc.rdoc_files = FileList.new %w[lib/**/*.rb *.rdoc doc/rdoc/markup_reference.rb] - PARSER_FILES
+  doc.meta_tags = {
+    "description" => "Documentation for RDoc, the Ruby documentation generator",
+    "keywords" => "rdoc,ruby,documentation,generator"
+  }
 end
 
 task "coverage" do

lib/rdoc/generator/template/darkfish/_head.rhtml

@@ -2,6 +2,10 @@
 
 <title><%= h @title %></title>
 
+<%- @options.meta_tags.each do |name, content| -%>
+<meta name="<%= h name %>" content="<%= h content %>">
+<%- end -%>
+
 <script type="text/javascript">
   var rdoc_rel_prefix = "<%= h asset_rel_prefix %>/";
   var index_rel_prefix = "<%= h rel_prefix %>/";

lib/rdoc/options.rb

@@ -344,6 +344,12 @@ class RDoc::Options
   # Indicates if files of test suites should be skipped
   attr_accessor :skip_tests
 
+  ##
+  # Meta tags to be included in the HTML header, such as keywords, description,
+  # author and others. This option is a hash where the keys are the meta tag
+  # name and the values are the content of the meta tag.
+  attr_accessor :meta_tags
+
   def initialize loaded_options = nil # :nodoc:
     init_ivars
     override loaded_options if loaded_options
@@ -392,6 +398,7 @@ def init_ivars # :nodoc:
     @encoding = Encoding::UTF_8
     @charset = @encoding.name
     @skip_tests = true
+    @meta_tags = {}
   end
 
   def init_with map # :nodoc:
@@ -416,6 +423,7 @@ def init_with map # :nodoc:
     @title          = map['title']
     @visibility     = map['visibility']
     @webcvs         = map['webcvs']
+    @meta_tags      = map['meta_tags']
 
     @rdoc_include = sanitize_path map['rdoc_include']
     @static_path  = sanitize_path map['static_path']
@@ -448,6 +456,7 @@ def override map # :nodoc:
     @title          = map['title']          if map.has_key?('title')
     @visibility     = map['visibility']     if map.has_key?('visibility')
     @webcvs         = map['webcvs']         if map.has_key?('webcvs')
+    @meta_tags      = map['meta_tags']      if map.has_key?('meta_tags')
 
     if map.has_key?('rdoc_include')
       @rdoc_include = sanitize_path map['rdoc_include']
@@ -475,7 +484,8 @@ def == other # :nodoc:
       @template       == other.template       and
       @title          == other.title          and
       @visibility     == other.visibility     and
-      @webcvs         == other.webcvs
+      @webcvs         == other.webcvs         and
+      @meta_tags      == other.meta_tags
   end
 
   ##
@@ -790,6 +800,15 @@ def parse argv
         @skip_tests = false
       end
 
+      opt.separator nil
+
+       opt.on("-mTAGS", "--meta-tags=TAGS",
+             "Meta tags to be included in the HTML head") do |value|
+        @meta_tags = JSON.parse(value)
+      rescue  JSON::ParserError, TypeError
+        raise OptionParser::InvalidArgument, "Invalid value for --meta-tags. Should be a JSON string"
+      end
+
       opt.separator nil
 
       opt.on("--extension=NEW=OLD", "-E",

lib/rdoc/task.rb

@@ -35,6 +35,7 @@
 require_relative '../rdoc'
 require 'rake'
 require 'rake/tasklib'
+require "json"
 
 ##
 # RDoc::Task creates the following rake tasks to generate and clean up RDoc
@@ -151,6 +152,12 @@ class RDoc::Task < Rake::TaskLib
 
   attr_accessor :external
 
+  ##
+  # Meta tags to be included in the HTML header, such as keywords, description,
+  # author and others. This option is a hash where the keys are the meta tag
+  # name and the values are the content of the meta tag.
+  attr_accessor :meta_tags
+
   ##
   # Create an RDoc task with the given name. See the RDoc::Task class overview
   # for documentation.
@@ -201,6 +208,7 @@ def defaults
     @template = nil
     @generator = nil
     @options = []
+    @meta_tags = nil
   end
 
   ##
@@ -271,12 +279,13 @@ def define
 
   def option_list
     result = @options.dup
-    result << "-o"       << @rdoc_dir
-    result << "--main"   << main      if main
-    result << "--markup" << markup    if markup
-    result << "--title"  << title     if title
-    result << "-T"       << template  if template
-    result << '-f'       << generator if generator
+    result << "-o"          << @rdoc_dir
+    result << "--main"      << main      if main
+    result << "--markup"    << markup    if markup
+    result << "--title"     << title     if title
+    result << "-T"          << template  if template
+    result << '-f'          << generator if generator
+    result << '--meta-tags' << meta_tags.to_json if meta_tags
     result
   end
 

test/rdoc/test_rdoc_generator_darkfish.rb

@@ -322,6 +322,22 @@ def test_title_escape
     assert_main_title(File.binread('index.html'), title)
   end
 
+  def test_meta_tags
+    @options.meta_tags = {
+      "keywords" => "ruby,programming,software",
+      "description" => "RDoc is an awesome documentation generator for Ruby!"
+    }
+    @g.generate
+
+    content = File.binread("index.html")
+
+    assert_match("<meta name=\"keywords\" content=\"ruby,programming,software\">", content)
+    assert_match(
+      "<meta name=\"description\" content=\"RDoc is an awesome documentation generator for Ruby!\">",
+      content
+    )
+  end
+
   ##
   # Asserts that +filename+ has a link count greater than 1 if hard links to
   # @tmpdir are supported.

test/rdoc/test_rdoc_options.rb

@@ -83,6 +83,7 @@ def test_to_yaml
       'visibility'           => :protected,
       'webcvs'               => nil,
       'skip_tests'           => true,
+      'meta_tags'            => {},
     }
 
     assert_equal expected, coder