1 files changed, 126 insertions, 0 deletions
diff --git a/lib/rubygems/resolver/specification.rb b/lib/rubygems/resolver/specification.rb
new file mode 100644
index 0000000000..d2098ef0e2
--- /dev/null
+++ b/lib/rubygems/resolver/specification.rb
@@ -0,0 +1,126 @@
+# frozen_string_literal: true
+
+##
+# A Resolver::Specification contains a subset of the information
+# contained in a Gem::Specification.  Only the information necessary for
+# dependency resolution in the resolver is included.
+
+class Gem::Resolver::Specification
+  ##
+  # The dependencies of the gem for this specification
+
+  attr_reader :dependencies
+
+  ##
+  # The name of the gem for this specification
+
+  attr_reader :name
+
+  ##
+  # The platform this gem works on.
+
+  attr_reader :platform
+
+  ##
+  # The set this specification came from.
+
+  attr_reader :set
+
+  ##
+  # The source for this specification
+
+  attr_reader :source
+
+  ##
+  # The Gem::Specification for this Resolver::Specification.
+  #
+  # Implementers, note that #install updates @spec, so be sure to cache the
+  # Gem::Specification in @spec when overriding.
+
+  attr_reader :spec
+
+  ##
+  # The version of the gem for this specification.
+
+  attr_reader :version
+
+  ##
+  # The required_ruby_version constraint for this specification.
+
+  attr_reader :required_ruby_version
+
+  ##
+  # The required_ruby_version constraint for this specification.
+
+  attr_reader :required_rubygems_version
+
+  ##
+  # Sets default instance variables for the specification.
+
+  def initialize
+    @dependencies = nil
+    @name         = nil
+    @platform     = nil
+    @set          = nil
+    @source       = nil
+    @version      = nil
+    @required_ruby_version = Gem::Requirement.default
+    @required_rubygems_version = Gem::Requirement.default
+  end
+
+  ##
+  # Fetches development dependencies if the source does not provide them by
+  # default (see APISpecification).
+
+  def fetch_development_dependencies # :nodoc:
+  end
+
+  ##
+  # The name and version of the specification.
+  #
+  # Unlike Gem::Specification#full_name, the platform is not included.
+
+  def full_name
+    "#{@name}-#{@version}"
+  end
+
+  ##
+  # Installs this specification using the Gem::Installer +options+.  The
+  # install method yields a Gem::Installer instance, which indicates the
+  # gem will be installed, or +nil+, which indicates the gem is already
+  # installed.
+  #
+  # After installation #spec is updated to point to the just-installed
+  # specification.
+
+  def install(options = {})
+    require_relative "../installer"
+
+    gem = download options
+
+    installer = Gem::Installer.at gem, options
+
+    yield installer if block_given?
+
+    @spec = installer.install
+  end
+
+  def download(options)
+    dir = options[:install_dir] || Gem.dir
+
+    Gem.ensure_gem_subdirectories dir
+
+    source.download spec, dir
+  end
+
+  ##
+  # Returns true if this specification is installable on this platform.
+
+  def installable_platform?
+    Gem::Platform.match_spec? spec
+  end
+
+  def local? # :nodoc:
+    false
+  end
+end