Add flexible enum support to ActiveHash::Enum

- Implement `enum` method to support both array and hash-style definitions
- Allow predicate methods generation for enum values
- Support Rails-like enum syntax: `enum status: [:draft, :published, :archived]`
- Support custom value mapping: `enum action: { like: 'LIKE', comment: 'COMMENT', ... }`
- Add comprehensive tests for both enum definition styles

This enhancement allows ActiveHash::Enum to handle enum definitions similar to
Rails, improving compatibility and ease of use. It provides a more flexible
way to define and use enums in ActiveHash models.

lib/enum/enum.rb

@@ -14,6 +14,17 @@ def enum_accessor(*field_names)
         reload
       end
 
+      def enum(columns)
+        columns.each do |column, values|
+          values = values.zip(values.map(&:to_s)).to_h if values.is_a?(Array)
+          values.each do |method, value|
+            define_method("#{method}?") do
+              send(column) == value
+            end
+          end
+        end
+      end
+
       def insert(record)
         super
         set_constant(record) if defined?(@enum_accessors)

spec/enum/enum_spec.rb

@@ -79,6 +79,73 @@ class Neighborhood < ActiveHash::Base
       expect(Movie::THE_INFORMANT.name).to eq('The Informant!')
       expect(Movie::IN_OUT.name).to eq('In & Out')
     end
+
+    describe "enum(columns)" do
+      it "defines a predicate method for each value in the enum" do
+        Article = Class.new(ActiveHash::Base) do
+          include ActiveHash::Enum
+
+          self.data = [
+            { name: 'Article 1', status: 'draft'},
+            { name: 'Article 2', status: 'published'},
+            { name: 'Article 3', status: 'archived'}
+          ]
+
+          enum_accessor :name
+
+          enum status: [:draft, :published, :archived]
+        end
+
+        expect(Article::ARTICLE_1.draft?).to be_truthy
+        expect(Article::ARTICLE_1.published?).to be_falsey
+        expect(Article::ARTICLE_1.archived?).to be_falsey
+
+        expect(Article::ARTICLE_2.draft?).to be_falsey
+        expect(Article::ARTICLE_2.published?).to be_truthy
+        expect(Article::ARTICLE_2.archived?).to be_falsey
+
+        expect(Article::ARTICLE_3.draft?).to be_falsey
+        expect(Article::ARTICLE_3.published?).to be_falsey
+        expect(Article::ARTICLE_3.archived?).to be_truthy
+      end
+
+      it "defines a predicate method for each value in the enum" do
+        NotifyType = Class.new(ActiveHash::Base) do
+          include ActiveHash::Enum
+
+          self.data = [
+            { name: 'Like', action: 'LIKE'},
+            { name: 'Comment', action: 'COMMENT'},
+            { name: 'Follow', action: 'FOLLOW'},
+            { name: 'Mention', action: 'MENTION'}
+          ]
+
+          enum_accessor :name
+
+          enum action: { like: 'LIKE', comment: 'COMMENT', follow: 'FOLLOW', mention: 'MENTION' }
+        end
+
+        expect(NotifyType::LIKE.like?).to be_truthy
+        expect(NotifyType::LIKE.comment?).to be_falsey
+        expect(NotifyType::LIKE.follow?).to be_falsey
+        expect(NotifyType::LIKE.mention?).to be_falsey
+
+        expect(NotifyType::COMMENT.like?).to be_falsey
+        expect(NotifyType::COMMENT.comment?).to be_truthy
+        expect(NotifyType::COMMENT.follow?).to be_falsey
+        expect(NotifyType::COMMENT.mention?).to be_falsey
+
+        expect(NotifyType::FOLLOW.like?).to be_falsey
+        expect(NotifyType::FOLLOW.comment?).to be_falsey
+        expect(NotifyType::FOLLOW.follow?).to be_truthy
+        expect(NotifyType::FOLLOW.mention?).to be_falsey
+
+        expect(NotifyType::MENTION.like?).to be_falsey
+        expect(NotifyType::MENTION.comment?).to be_falsey
+        expect(NotifyType::MENTION.follow?).to be_falsey
+        expect(NotifyType::MENTION.mention?).to be_truthy
+      end
+    end
   end
 
   context "ActiveHash with an enum_accessor set" do