@@ -4,6 +4,9 @@
 * The default output encoding for RDoc is now UTF-8. Previously RDoc used
 the default external encoding which was determined from your locale.
 Issue #106 by Justin Baker.
+* Removed RDoc::RI::Paths::SYSDIR and ::SITEDIR. These were hidden
+constants so no breakage is expected. Use RDoc::RI::Paths::system_dir
+and ::site_dir instead.
 
 * Minor enhancements
 * Added Markdown as a supported format. The markdown format can be set on a
@@ -16,6 +19,8 @@
 * RDoc now tracks use of extend. Pull request #118 by Michael Granger.
 * RDoc now tracks methods that use super. Pull request #116 by Erik
 Hollensbe.
+* Added methods ::system_dir, ::site_dir, ::home_dir and ::gem_dir to fetch
+the components of RDoc::RI::Paths.path individually.
 
 * Bug fixes
 * A word that is directly followed by a multi-word tidy link label no longer

@@ -1,7 +1,8 @@
 require 'rdoc/ri'
 
 ##
-# The directories where ri data lives.
+# The directories where ri data lives. Paths can be enumerated via ::each, or
+# queried individually via ::system_dir, ::site_dir, ::home_dir and ::gem_dir.
 
 module RDoc::RI::Paths
 
@@ -10,15 +11,12 @@ module RDoc::RI::Paths
 
 version = RbConfig::CONFIG['ruby_version']
 
-base = if RbConfig::CONFIG.key? 'ridir' then
+BASE = if RbConfig::CONFIG.key? 'ridir' then
 File.join RbConfig::CONFIG['ridir'], version
 else
 File.join RbConfig::CONFIG['datadir'], 'ri', version
 end
 
-SYSDIR = File.join base, "system"
-SITEDIR = File.join base, "site"
-
 homedir = begin
 File.expand_path('~')
 rescue ArgumentError
@@ -47,14 +45,16 @@ module RDoc::RI::Paths
 # :extra:: ri data directory from the command line. Yielded for each
 # entry in +extra_dirs+
 
-def self.each system, site, home, gems, *extra_dirs # :yields: directory, type
+def self.each system = true, site = true, home = true, gems = true, *extra_dirs # :yields: directory, type
+return enum_for __method__ unless block_given?
+
 extra_dirs.each do |dir|
 yield dir, :extra
 end
 
-yield SYSDIR, :system if system
-yield SITEDIR, :site if site
-yield HOMEDIR, :home if home and HOMEDIR
+yield system_dir, :system if system
+yield site_dir, :site if site
+yield home_dir, :home if home and HOMEDIR
 
 gemdirs.each do |dir|
 yield dir, :gem
@@ -63,6 +63,17 @@ def self.each system, site, home, gems, *extra_dirs # :yields: directory, type
 nil
 end
 
+##
+# The ri directory for the gem with +gem_name+.
+
+def self.gem_dir name, version
+req = Gem::Requirement.new "= #{version}"
+
+spec = Gem::Specification.find_by_name name, req
+
+File.join spec.doc_dir, 'ri'
+end
+
 ##
 # The latest installed gems' ri directories
 
@@ -96,13 +107,24 @@ def self.gemdirs
 @gemdirs = []
 end
 
+##
+# The location of the rdoc data in the user's home directory.
+#
+# Like ::system, ri data in the user's home directory is rare and predates
+# libraries distributed via RubyGems. ri data is rarely generated into this
+# directory.
+
+def self.home_dir
+HOMEDIR
+end
+
 ##
 # Returns existing directories from the selected documentation directories
 # as an Array.
 #
 # See also ::each
 
-def self.path(system, site, home, gems, *extra_dirs)
+def self.path(system = true, site = true, home = true, gems = true, *extra_dirs)
 path = raw_path system, site, home, gems, *extra_dirs
 
 path.select { |directory| File.directory? directory }
@@ -124,5 +146,29 @@ def self.raw_path(system, site, home, gems, *extra_dirs)
 path.compact
 end
 
+##
+# The location of ri data installed into the site dir.
+#
+# Historically this was available for documentation installed by ruby
+# libraries predating RubyGems. It is unlikely to contain any content for
+# modern ruby installations.
+
+def self.site_dir
+File.join BASE, 'site'
+end
+
+##
+# The location of the built-in ri data.
+#
+# This data is built automatically when `make` is run when ruby is
+# installed. If you did not install ruby by hand you may need to install
+# the documentation yourself. Please consult the documentation for your
+# package manager or ruby installer for details. You can also use the
+# rdoc-data gem to install system ri data for common versions of ruby.
+
+def self.system_dir
+File.join BASE, 'system'
+end
+
 end
 

@@ -6,40 +6,74 @@ def setup
 super
 
 RDoc::RI::Paths.instance_variable_set :@gemdirs, %w[/nonexistent/gemdir]
+
+@spec = Gem::Specification.new 'test', '1.0'
+@spec.loaded_from =
+File.expand_path '../specifications/test-1.0.gemspec', __FILE__
+
+Gem::Specification.reset
+Gem::Specification.all = [@spec]
 end
 
 def teardown
 super
 
 RDoc::RI::Paths.instance_variable_set :@gemdirs, nil
+Gem::Specification.reset
+end
+
+def test_class_gem_dir
+dir = RDoc::RI::Paths.gem_dir 'test', '1.0'
+
+expected = File.expand_path '../doc/test-1.0/ri', __FILE__
+
+assert_equal expected, dir
+end
+
+def test_class_home_dir
+dir = RDoc::RI::Paths.home_dir
+
+assert_equal RDoc::RI::Paths::HOMEDIR, dir
 end
 
 def test_class_path_nonexistent
 temp_dir do |dir|
 nonexistent = File.join dir, 'nonexistent'
-path = RDoc::RI::Paths.path true, true, true, true, nonexistent
+dir = RDoc::RI::Paths.path true, true, true, true, nonexistent
 
-refute_includes path, nonexistent
+refute_includes dir, nonexistent
 end
 end
 
 def test_class_raw_path
 path = RDoc::RI::Paths.raw_path true, true, true, true
 
-assert_equal RDoc::RI::Paths::SYSDIR, path.shift
-assert_equal RDoc::RI::Paths::SITEDIR, path.shift
-assert_equal RDoc::RI::Paths::HOMEDIR, path.shift
-assert_equal '/nonexistent/gemdir', path.shift
+assert_equal RDoc::RI::Paths.system_dir, path.shift
+assert_equal RDoc::RI::Paths.site_dir, path.shift
+assert_equal RDoc::RI::Paths.home_dir, path.shift
+assert_equal '/nonexistent/gemdir', path.shift
 end
 
 def test_class_raw_path_extra_dirs
 path = RDoc::RI::Paths.raw_path true, true, true, true, '/nonexistent'
 
-assert_equal '/nonexistent', path.shift
-assert_equal RDoc::RI::Paths::SYSDIR, path.shift
-assert_equal RDoc::RI::Paths::SITEDIR, path.shift
-assert_equal RDoc::RI::Paths::HOMEDIR, path.shift
-assert_equal '/nonexistent/gemdir', path.shift
+assert_equal '/nonexistent', path.shift
+assert_equal RDoc::RI::Paths.system_dir, path.shift
+assert_equal RDoc::RI::Paths.site_dir, path.shift
+assert_equal RDoc::RI::Paths.home_dir, path.shift
+assert_equal '/nonexistent/gemdir', path.shift
+end
+
+def test_class_site_dir
+dir = RDoc::RI::Paths.site_dir
+
+assert_equal File.join(RDoc::RI::Paths::BASE, 'site'), dir
+end
+
+def test_class_system_dir
+dir = RDoc::RI::Paths.system_dir
+
+assert_equal File.join(RDoc::RI::Paths::BASE, 'system'), dir
 end
 
 end