1 files changed, 85 insertions, 0 deletions
diff --git a/lib/bundler/current_ruby.rb b/lib/bundler/current_ruby.rb
new file mode 100644
index 0000000000..cca40100ad
--- /dev/null
+++ b/lib/bundler/current_ruby.rb
@@ -0,0 +1,85 @@
+# frozen_string_literal: true
+module Bundler
+  # Returns current version of Ruby
+  #
+  # @return [CurrentRuby] Current version of Ruby
+  def self.current_ruby
+    @current_ruby ||= CurrentRuby.new
+  end
+
+  class CurrentRuby
+    KNOWN_MINOR_VERSIONS = %w(
+      1.8
+      1.9
+      2.0
+      2.1
+      2.2
+      2.3
+      2.4
+      2.5
+    ).freeze
+
+    KNOWN_MAJOR_VERSIONS = KNOWN_MINOR_VERSIONS.map {|v| v.split(".", 2).first }.uniq.freeze
+
+    KNOWN_PLATFORMS = %w(
+      jruby
+      maglev
+      mingw
+      mri
+      mswin
+      mswin64
+      rbx
+      ruby
+      x64_mingw
+    ).freeze
+
+    def ruby?
+      !mswin? && (!defined?(RUBY_ENGINE) || RUBY_ENGINE == "ruby" || RUBY_ENGINE == "rbx" || RUBY_ENGINE == "maglev")
+    end
+
+    def mri?
+      !mswin? && (!defined?(RUBY_ENGINE) || RUBY_ENGINE == "ruby")
+    end
+
+    def rbx?
+      ruby? && defined?(RUBY_ENGINE) && RUBY_ENGINE == "rbx"
+    end
+
+    def jruby?
+      defined?(RUBY_ENGINE) && RUBY_ENGINE == "jruby"
+    end
+
+    def maglev?
+      defined?(RUBY_ENGINE) && RUBY_ENGINE == "maglev"
+    end
+
+    def mswin?
+      Bundler::WINDOWS
+    end
+
+    def mswin64?
+      Bundler::WINDOWS && Bundler.local_platform != Gem::Platform::RUBY && Bundler.local_platform.os == "mswin64" && Bundler.local_platform.cpu == "x64"
+    end
+
+    def mingw?
+      Bundler::WINDOWS && Bundler.local_platform != Gem::Platform::RUBY && Bundler.local_platform.os == "mingw32" && Bundler.local_platform.cpu != "x64"
+    end
+
+    def x64_mingw?
+      Bundler::WINDOWS && Bundler.local_platform != Gem::Platform::RUBY && Bundler.local_platform.os == "mingw32" && Bundler.local_platform.cpu == "x64"
+    end
+
+    (KNOWN_MINOR_VERSIONS + KNOWN_MAJOR_VERSIONS).each do |version|
+      trimmed_version = version.tr(".", "")
+      define_method(:"on_#{trimmed_version}?") do
+        RUBY_VERSION.start_with?("#{version}.")
+      end
+
+      KNOWN_PLATFORMS.each do |platform|
+        define_method(:"#{platform}_#{trimmed_version}?") do
+          send(:"#{platform}?") && send(:"on_#{trimmed_version}?")
+        end
+      end
+    end
+  end
+end