Add class Repubmark::Elems::CustomBlock

lib/repubmark.rb

@@ -25,6 +25,7 @@ require_relative 'repubmark/elems/canvas'
 # Always inside Canvas
 require_relative 'repubmark/elems/blockquote'
 require_relative 'repubmark/elems/code_block'
+require_relative 'repubmark/elems/custom_block'
 require_relative 'repubmark/elems/figures'
 require_relative 'repubmark/elems/iframe'
 require_relative 'repubmark/elems/paragraph'

lib/repubmark/elems/canvas.rb

@@ -37,6 +37,13 @@ module Repubmark
         nil
       end
 
+      def custom
+        custom_block = CustomBlock.new self
+        @items << custom_block
+        yield custom_block
+        nil
+      end
+
       def iframe(*args, **kwargs)
         iframe = Iframe.new self, *args, **kwargs
         @items << iframe

lib/repubmark/elems/custom_block.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Repubmark
+  module Elems
+    class CustomBlock < Base
+      FORMATS = %i[html gemtext].freeze
+
+      parents :Canvas
+
+      def initialize(parent)
+        super parent
+        @for = {}
+      end
+
+      #################
+      # Basic methods #
+      #################
+
+      def to_html
+        "<div>\n#{@for[:html].strip}\n</div>\n".freeze if @for[:html]
+      end
+
+      def to_gemtext
+        "#{@for[:gemtext].strip}\n".freeze if @for[:gemtext]
+      end
+
+      ###################
+      # Builder methods #
+      ###################
+
+      def for(format, str)
+        raise 'Invalid format' unless FORMATS.include? format
+        raise 'Format already configured' if @for.key? format
+
+        str = String(str).strip.freeze
+        return if str.empty?
+
+        @for[format] = str
+      end
+    end
+  end
+end