1 files changed, 133 insertions, 0 deletions
diff --git a/lib/bundler/ruby_version.rb b/lib/bundler/ruby_version.rb
new file mode 100644
index 0000000000..aeff07582e
--- /dev/null
+++ b/lib/bundler/ruby_version.rb
@@ -0,0 +1,133 @@
+# frozen_string_literal: true
+
+module Bundler
+  class RubyVersion
+    attr_reader :versions,
+      :patchlevel,
+      :engine,
+      :engine_versions,
+      :gem_version,
+      :engine_gem_version
+
+    def initialize(versions, patchlevel, engine, engine_version)
+      # The parameters to this method must satisfy the
+      # following constraints, which are verified in
+      # the DSL:
+      #
+      # * If an engine is specified, an engine version
+      #   must also be specified
+      # * If an engine version is specified, an engine
+      #   must also be specified
+      # * If the engine is "ruby", the engine version
+      #   must not be specified, or the engine version
+      #   specified must match the version.
+
+      @versions = Array(versions).map do |v|
+        normalized_v = normalize_version(v)
+
+        unless Gem::Requirement::PATTERN.match?(normalized_v)
+          raise InvalidArgumentError, "#{v} is not a valid requirement on the Ruby version"
+        end
+
+        op, v = Gem::Requirement.parse(normalized_v)
+        op == "=" ? v.to_s : "#{op} #{v}"
+      end
+
+      @gem_version        = Gem::Requirement.create(@versions.first).requirements.first.last
+      @input_engine       = engine&.to_s
+      @engine             = engine&.to_s || "ruby"
+      @engine_versions    = (engine_version && Array(engine_version)) || @versions
+      @engine_gem_version = Gem::Requirement.create(@engine_versions.first).requirements.first.last
+      @patchlevel         = patchlevel || (@gem_version.prerelease? ? "-1" : nil)
+    end
+
+    def to_s(versions = self.versions)
+      output = String.new("ruby #{versions_string(versions)}")
+      output << " (#{engine} #{versions_string(engine_versions)})" unless engine == "ruby"
+
+      output
+    end
+
+    # @private
+    PATTERN = /
+      ruby\s
+      (\d+\.\d+\.\d+(?:\.\S+)?) # ruby version
+      (?:p(-?\d+))? # optional patchlevel
+      (?:\s\((\S+)\s(.+)\))? # optional engine info
+    /xo
+
+    # Returns a RubyVersion from the given string.
+    # @param [String] the version string to match.
+    # @return [RubyVersion,Nil] The version if the string is a valid RubyVersion
+    #         description, and nil otherwise.
+    def self.from_string(string)
+      new($1, $2, $3, $4) if string =~ PATTERN
+    end
+
+    def single_version_string
+      to_s(gem_version)
+    end
+
+    def ==(other)
+      versions == other.versions &&
+        engine == other.engine &&
+        engine_versions == other.engine_versions
+    end
+
+    def host
+      @host ||= [
+        RbConfig::CONFIG["host_cpu"],
+        RbConfig::CONFIG["host_vendor"],
+        RbConfig::CONFIG["host_os"],
+      ].join("-")
+    end
+
+    # Returns a tuple of these things:
+    #   [diff, this, other]
+    #   The priority of attributes are
+    #   1. engine
+    #   2. ruby_version
+    #   3. engine_version
+    def diff(other)
+      raise ArgumentError, "Can only diff with a RubyVersion, not a #{other.class}" unless other.is_a?(RubyVersion)
+      if engine != other.engine && @input_engine
+        [:engine, engine, other.engine]
+      elsif versions.empty? || !matches?(versions, other.gem_version)
+        [:version, versions_string(versions), versions_string(other.versions)]
+      elsif @input_engine && !matches?(engine_versions, other.engine_gem_version)
+        [:engine_version, versions_string(engine_versions), versions_string(other.engine_versions)]
+      end
+    end
+
+    def versions_string(versions)
+      Array(versions).join(", ")
+    end
+
+    def self.system
+      ruby_engine = RUBY_ENGINE.dup
+      ruby_version = Gem.ruby_version.to_s
+      ruby_engine_version = RUBY_ENGINE == "ruby" ? ruby_version : RUBY_ENGINE_VERSION.dup
+      patchlevel = RUBY_PATCHLEVEL.to_s
+
+      @system ||= RubyVersion.new(ruby_version, patchlevel, ruby_engine, ruby_engine_version)
+    end
+
+    private
+
+    # Ruby's official preview version format uses a `-`: Example: 3.3.0-preview2
+    # However, RubyGems recognizes preview version format with a `.`: Example: 3.3.0.preview2
+    # Returns version string after replacing `-` with `.`
+    def normalize_version(version)
+      version.tr("-", ".")
+    end
+
+    def matches?(requirements, version)
+      # Handles RUBY_PATCHLEVEL of -1 for instances like ruby-head
+      return requirements == version if requirements.to_s == "-1" || version.to_s == "-1"
+
+      Array(requirements).all? do |requirement|
+        Gem::Requirement.create(requirement).satisfied_by?(Gem::Version.create(version))
+      end
+    end
+  end
+end