1 files changed, 125 insertions, 0 deletions
diff --git a/lib/rubygems/name_tuple.rb b/lib/rubygems/name_tuple.rb
new file mode 100644
index 0000000000..cbdf4d7ac5
--- /dev/null
+++ b/lib/rubygems/name_tuple.rb
@@ -0,0 +1,125 @@
+# frozen_string_literal: true
+
+##
+#
+# Represents a gem of name +name+ at +version+ of +platform+. These
+# wrap the data returned from the indexes.
+
+class Gem::NameTuple
+  def initialize(name, version, platform = Gem::Platform::RUBY)
+    @name = name
+    @version = version
+
+    platform &&= platform.to_s
+    platform = Gem::Platform::RUBY if !platform || platform.empty?
+    @platform = platform
+  end
+
+  attr_reader :name, :version, :platform
+
+  ##
+  # Turn an array of [name, version, platform] into an array of
+  # NameTuple objects.
+
+  def self.from_list(list)
+    list.map {|t| new(*t) }
+  end
+
+  ##
+  # Turn an array of NameTuple objects back into an array of
+  # [name, version, platform] tuples.
+
+  def self.to_basic(list)
+    list.map(&:to_a)
+  end
+
+  ##
+  # A null NameTuple, ie name=nil, version=0
+
+  def self.null
+    new nil, Gem::Version.new(0), nil
+  end
+
+  ##
+  # Returns the full name (name-version) of this Gem.  Platform information is
+  # included if it is not the default Ruby platform.  This mimics the behavior
+  # of Gem::Specification#full_name.
+
+  def full_name
+    case @platform
+    when nil, "", Gem::Platform::RUBY
+      "#{@name}-#{@version}"
+    else
+      "#{@name}-#{@version}-#{@platform}"
+    end
+  end
+
+  ##
+  # Indicate if this NameTuple matches the current platform.
+
+  def match_platform?
+    Gem::Platform.match_gem? @platform, @name
+  end
+
+  ##
+  # Indicate if this NameTuple is for a prerelease version.
+  def prerelease?
+    @version.prerelease?
+  end
+
+  ##
+  # Return the name that the gemspec file would be
+
+  def spec_name
+    "#{full_name}.gemspec"
+  end
+
+  ##
+  # Convert back to the [name, version, platform] tuple
+
+  def to_a
+    [@name, @version, @platform]
+  end
+
+  alias_method :deconstruct, :to_a
+
+  def deconstruct_keys(keys)
+    { name: @name, version: @version, platform: @platform }
+  end
+
+  def inspect # :nodoc:
+    "#<Gem::NameTuple #{@name}, #{@version}, #{@platform}>"
+  end
+
+  alias_method :to_s, :inspect # :nodoc:
+
+  def <=>(other)
+    [@name, @version, Gem::Platform.sort_priority(@platform)] <=>
+      [other.name, other.version, Gem::Platform.sort_priority(other.platform)]
+  end
+
+  include Comparable
+
+  ##
+  # Compare with +other+. Supports another NameTuple or an Array
+  # in the [name, version, platform] format.
+
+  def ==(other)
+    case other
+    when self.class
+      @name == other.name &&
+        @version == other.version &&
+        @platform == other.platform
+    when Array
+      to_a == other
+    else
+      false
+    end
+  end
+
+  alias_method :eql?, :==
+
+  def hash
+    to_a.hash
+  end
+end