1 files changed, 79 insertions, 0 deletions
diff --git a/lib/bundler/settings/validator.rb b/lib/bundler/settings/validator.rb
new file mode 100644
index 0000000000..9aa1627fb2
--- /dev/null
+++ b/lib/bundler/settings/validator.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+module Bundler
+  class Settings
+    class Validator
+      class Rule
+        attr_reader :description
+
+        def initialize(keys, description, &validate)
+          @keys = keys
+          @description = description
+          @validate = validate
+        end
+
+        def validate!(key, value, settings)
+          instance_exec(key, value, settings, &@validate)
+        end
+
+        def fail!(key, value, *reasons)
+          reasons.unshift @description
+          raise InvalidOption, "Setting `#{key}` to #{value.inspect} failed:\n#{reasons.map {|r| " - #{r}" }.join("\n")}"
+        end
+
+        def set(settings, key, value, *reasons)
+          hash_key = k(key)
+          return if settings[hash_key] == value
+          reasons.unshift @description
+          Bundler.ui.info "Setting `#{key}` to #{value.inspect}, since #{reasons.join(", ")}"
+          if value.nil?
+            settings.delete(hash_key)
+          else
+            settings[hash_key] = value
+          end
+        end
+
+        def k(key)
+          Bundler.settings.key_for(key)
+        end
+      end
+
+      def self.rules
+        @rules ||= Hash.new {|h, k| h[k] = [] }
+      end
+      private_class_method :rules
+
+      def self.rule(keys, description, &blk)
+        rule = Rule.new(keys, description, &blk)
+        keys.each {|k| rules[k] << rule }
+      end
+      private_class_method :rule
+
+      def self.validate!(key, value, settings)
+        rules_to_validate = rules[key]
+        rules_to_validate.each {|rule| rule.validate!(key, value, settings) }
+      end
+
+      rule %w[path path.system], "path and path.system are mutually exclusive" do |key, value, settings|
+        if key == "path" && value
+          set(settings, "path.system", nil)
+        elsif key == "path.system" && value
+          set(settings, :path, nil)
+        end
+      end
+
+      rule %w[with without], "a group cannot be in both `with` & `without` simultaneously" do |key, value, settings|
+        with = settings.fetch(k(:with), "").split(":").map(&:to_sym)
+        without = settings.fetch(k(:without), "").split(":").map(&:to_sym)
+
+        other_key = key == "with" ? :without : :with
+        other_setting = key == "with" ? without : with
+
+        conflicting = with & without
+        if conflicting.any?
+          fail!(key, value, "`#{other_key}` is current set to #{other_setting.inspect}", "the `#{conflicting.join("`, `")}` groups conflict")
+        end
+      end
+    end
+  end
+end