[ Jekyll / Ruby / Json ]: Generate json out of Jekyll posts

jekyll-json.rb

require 'json'

module Jekyll

  module JsonContent
    class Index < Jekyll::Page
      attr_reader :page

      def initialize site, base, dir, page
        @site = site
        @base = base
        @dir  = dir
        @name = page.name
        @page = page
        self.process @name
        self.read_yaml File.join(base, '_layouts'), 'api.json'
      end

      def permalink
        page.url.sub(/html$/, 'json')
      end

      def output
        { title: page.data.fetch('title'), posts: post_list }.to_json
      end

      def post_list
        site.posts.map { |post| Blurb.new(post).output }
      end
    end

    class Page < Jekyll::Page
      attr_reader :post

      def initialize site, base, dir, post
        @site = site
        @base = base
        @dir  = dir
        @name = post.name
        @post = post
        self.process @name
        self.read_yaml File.join(base, '_layouts'), 'api.json'
      end

      def permalink
        "#{post.id}.json"
      end

      def output
        Hash.new.tap do |hash|
          hash[:post]     = { title: post.title, content: post.content }
          hash[:next]     = next_output if !post.next.nil?
          hash[:previous] = prev_output if !post.previous.nil?
          hash[:related_posts] = RelatedPosts.new(post, site).output
        end.to_json
      end

      def prev_output
        Blurb.new(post.previous).output
      end

      def next_output
        Blurb.new(post.next).output
      end

    end

    class Blurb
      attr_reader :post

      def initialize post
        @post = post
      end

      def output
        { title: post.title, excerpt: post.excerpt, url: "#{post.id}.json" }
      end

    end

    class RelatedPosts
      attr_reader :post, :site

      def initialize post, site
        @post = post
        @site = site
      end

      def output
        return [] unless post.instance_of? Post
        post.related_posts(site.posts).map { |post| Blurb.new(post).output }
      end

    end

  end

  class JsonPageGenerator < Generator
    safe true

    def generate(site)
      dir = site.config.fetch('destination')

      site.posts.each do |post|
        site.pages << JsonContent::Page.new(site, site.source, dir, post)
      end

      index = site.pages.find { |page| page.name == 'index.html' }
      site.pages << JsonContent::Index.new(site, site.source, dir, index)
    end

  end

end

Hello, could you tell me how to use it?