1 files changed, 94 insertions, 0 deletions
diff --git a/lib/bundler/resolver/candidate.rb b/lib/bundler/resolver/candidate.rb
new file mode 100644
index 0000000000..9e8b913335
--- /dev/null
+++ b/lib/bundler/resolver/candidate.rb
@@ -0,0 +1,94 @@
+# frozen_string_literal: true
+
+require_relative "spec_group"
+
+module Bundler
+  class Resolver
+    #
+    # This class is a PubGrub compatible "Version" class that takes Bundler
+    # resolution complexities into account.
+    #
+    # Each Resolver::Candidate has a underlying `Gem::Version` plus a set of
+    # platforms. For example, 1.1.0-x86_64-linux is a different resolution candidate
+    # from 1.1.0 (generic). This is because different platform variants of the
+    # same gem version can bring different dependencies, so they need to be
+    # considered separately.
+    #
+    # Some candidates may also keep some information explicitly about the
+    # package they refer to. These candidates are referred to as "canonical" and
+    # are used when materializing resolution results back into RubyGems
+    # specifications that can be installed, written to lock files, and so on.
+    #
+    class Candidate
+      include Comparable
+
+      attr_reader :version
+
+      def initialize(version, specs: [])
+        @spec_group = Resolver::SpecGroup.new(specs)
+        @version = Gem::Version.new(version)
+        @ruby_only = specs.map(&:platform).uniq == [Gem::Platform::RUBY]
+      end
+
+      def dependencies
+        @spec_group.dependencies
+      end
+
+      def to_specs(package)
+        return [] if package.meta?
+
+        @spec_group.to_specs(package.force_ruby_platform?)
+      end
+
+      def generic!
+        @ruby_only = true
+
+        self
+      end
+
+      def platform_specific!
+        @ruby_only = false
+
+        self
+      end
+
+      def prerelease?
+        @version.prerelease?
+      end
+
+      def segments
+        @version.segments
+      end
+
+      def sort_obj
+        [@version, @ruby_only ? -1 : 1]
+      end
+
+      def <=>(other)
+        return unless other.is_a?(self.class)
+
+        sort_obj <=> other.sort_obj
+      end
+
+      def ==(other)
+        return unless other.is_a?(self.class)
+
+        sort_obj == other.sort_obj
+      end
+
+      def eql?(other)
+        return unless other.is_a?(self.class)
+
+        sort_obj.eql?(other.sort_obj)
+      end
+
+      def hash
+        sort_obj.hash
+      end
+
+      def to_s
+        @version.to_s
+      end
+    end
+  end
+end