1 files changed, 94 insertions, 0 deletions
diff --git a/lib/bundler/current_ruby.rb b/lib/bundler/current_ruby.rb
new file mode 100644
index 0000000000..17c7655adb
--- /dev/null
+++ b/lib/bundler/current_ruby.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+require_relative "rubygems_ext"
+
+module Bundler
+  # Returns current version of Ruby
+  #
+  # @return [CurrentRuby] Current version of Ruby
+  def self.current_ruby
+    @current_ruby ||= CurrentRuby.new
+  end
+
+  class CurrentRuby
+    ALL_RUBY_VERSIONS = [*18..27, *30..34, *40..41].freeze
+    KNOWN_MINOR_VERSIONS = ALL_RUBY_VERSIONS.map {|v| v.digits.reverse.join(".") }.freeze
+    KNOWN_MAJOR_VERSIONS = ALL_RUBY_VERSIONS.map {|v| v.digits.last.to_s }.uniq.freeze
+    PLATFORM_MAP = {
+      ruby: [Gem::Platform::RUBY, CurrentRuby::ALL_RUBY_VERSIONS],
+      mri: [Gem::Platform::RUBY, CurrentRuby::ALL_RUBY_VERSIONS],
+      rbx: [Gem::Platform::RUBY],
+      truffleruby: [Gem::Platform::RUBY],
+      jruby: [Gem::Platform::JAVA, [18, 19]],
+      windows: [Gem::Platform::WINDOWS, CurrentRuby::ALL_RUBY_VERSIONS],
+      # deprecated
+      mswin: [Gem::Platform::MSWIN, CurrentRuby::ALL_RUBY_VERSIONS],
+      mswin64: [Gem::Platform::MSWIN64, CurrentRuby::ALL_RUBY_VERSIONS - [18]],
+      mingw: [Gem::Platform::UNIVERSAL_MINGW, CurrentRuby::ALL_RUBY_VERSIONS],
+      x64_mingw: [Gem::Platform::UNIVERSAL_MINGW, CurrentRuby::ALL_RUBY_VERSIONS - [18, 19]],
+    }.each_with_object({}) do |(platform, spec), hash|
+      hash[platform] = spec[0]
+      spec[1]&.each {|version| hash[:"#{platform}_#{version}"] = spec[0] }
+    end.freeze
+
+    def ruby?
+      return true if Bundler::MatchPlatform.generic_local_platform_is_ruby?
+
+      !windows? && (RUBY_ENGINE == "ruby" || RUBY_ENGINE == "rbx" || RUBY_ENGINE == "maglev" || RUBY_ENGINE == "truffleruby")
+    end
+
+    def mri?
+      !windows? && RUBY_ENGINE == "ruby"
+    end
+
+    def rbx?
+      ruby? && RUBY_ENGINE == "rbx"
+    end
+
+    def jruby?
+      RUBY_ENGINE == "jruby"
+    end
+
+    def maglev?
+      removed_message =
+        "`CurrentRuby#maglev?` was removed with no replacement. Please use the " \
+        "built-in Ruby `RUBY_ENGINE` constant to check the Ruby implementation you are running on."
+      SharedHelpers.feature_removed!(removed_message)
+    end
+
+    def truffleruby?
+      RUBY_ENGINE == "truffleruby"
+    end
+
+    def windows?
+      Gem.win_platform?
+    end
+    alias_method :mswin?, :windows?
+    alias_method :mswin64?, :windows?
+    alias_method :mingw?, :windows?
+    alias_method :x64_mingw?, :windows?
+
+    (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
+
+      PLATFORM_MAP.keys.each do |platform|
+        define_method(:"#{platform}_#{trimmed_version}?") do
+          send(:"#{platform}?") && send(:"on_#{trimmed_version}?")
+        end
+      end
+
+      define_method(:"maglev_#{trimmed_version}?") do
+        removed_message =
+          "`CurrentRuby##{__method__}` was removed with no replacement. Please use the " \
+          "built-in Ruby `RUBY_ENGINE` and `RUBY_VERSION` constants to perform a similar check."
+
+        SharedHelpers.feature_removed!(removed_message)
+
+        send(:"maglev?") && send(:"on_#{trimmed_version}?")
+      end
+    end
+  end
+end