1 files changed, 85 insertions, 0 deletions
diff --git a/lib/bundler/resolver/candidate.rb b/lib/bundler/resolver/candidate.rb
new file mode 100644
index 0000000000..5298b2530f
--- /dev/null
+++ b/lib/bundler/resolver/candidate.rb
@@ -0,0 +1,85 @@
+# 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 lockfiles, and so on.
+    #
+    class Candidate
+      include Comparable
+
+      attr_reader :version
+
+      def initialize(version, group: nil, priority: -1)
+        @spec_group = group || SpecGroup.new([])
+        @version = Gem::Version.new(version)
+        @priority = priority
+      end
+
+      def dependencies
+        @spec_group.dependencies
+      end
+
+      def to_specs(package, most_specific_locked_platform)
+        return [] if package.meta?
+
+        @spec_group.to_specs(package.force_ruby_platform?, most_specific_locked_platform)
+      end
+
+      def prerelease?
+        @version.prerelease?
+      end
+
+      def segments
+        @version.segments
+      end
+
+      def <=>(other)
+        return unless other.is_a?(self.class)
+
+        version_comparison = version <=> other.version
+        return version_comparison unless version_comparison.zero?
+
+        priority <=> other.priority
+      end
+
+      def ==(other)
+        return unless other.is_a?(self.class)
+
+        version == other.version && priority == other.priority
+      end
+
+      def eql?(other)
+        return unless other.is_a?(self.class)
+
+        version.eql?(other.version) && priority.eql?(other.priority)
+      end
+
+      def hash
+        [@version, @priority].hash
+      end
+
+      def to_s
+        @version.to_s
+      end
+
+      protected
+
+      attr_reader :priority
+    end
+  end
+end