Implement first version of Markdown exporter

bin/org-ruby

@@ -17,7 +17,7 @@ options_parser = OptionParser.new do |opts|
     options[:debug] = true
   end
 
-  opts.on("-t", "--translate FORMAT", [:html, :textile],
+  opts.on("-t", "--translate FORMAT", [:html, :textile, :markdown],
           "Translate the ORG file to the specified format.") do |v|
     options[:format] = v
   end
@@ -43,9 +43,8 @@ begin
     $DEBUG = true if options[:debug]
     puts p.to_html if options[:format] == :html
     puts p.to_textile if options[:format] == :textile
+    puts p.to_markdown if options[:format] == :markdown
   end
 rescue OptionParser::ParseError
   puts options_parser
 end
-
-

lib/org-ruby.rb

@@ -15,6 +15,9 @@
 require 'org-ruby/textile_output_buffer'
 require 'org-ruby/textile_symbol_replace'
 
+# Markdown exporter
+require 'org-ruby/markdown_output_buffer'
+
 # Tilt support
 require 'org-ruby/tilt'
 

lib/org-ruby/markdown_output_buffer.rb

@@ -0,0 +1,109 @@
+require 'stringio'
+
+module Orgmode
+
+  class MarkdownOutputBuffer < OutputBuffer
+
+    def initialize(output)
+      super(output)
+    end
+
+    def push_mode(mode, indent)
+      super(mode, indent)
+    end
+
+    def pop_mode(mode = nil)
+      m = super(mode)
+      @list_indent_stack.pop
+      m
+    end
+
+    # Maps org markup to markdown markup.
+    MarkdownMap = {
+      "*" => "**",
+      "/" => "*",
+      "_" => "*",
+      "=" => "`",
+      "~" => "`",
+      "+" => "~~"
+    }
+
+    # Handles inline formatting for markdown.
+    def inline_formatting(input)
+      @re_help.rewrite_emphasis input do |marker, body|
+        m = MarkdownMap[marker]
+        "#{m}#{body}#{m}"
+      end
+      @re_help.rewrite_subp input do |type, text|
+        if type == "_" then
+          "<sub>#{text}</sub>"
+        elsif type == "^" then
+          "<sup>#{text}</sup>"
+        end
+      end
+      @re_help.rewrite_links input do |link, defi|
+        # We don't add a description for images in links, because its
+        # empty value forces the image to be inlined.
+        defi ||= link unless link =~ @re_help.org_image_file_regexp
+        link = link.gsub(/ /, "%%20")
+
+        if defi =~ @re_help.org_image_file_regexp
+          "![#{defi}](#{defi})"
+        elsif defi
+          "[#{defi}](#{link})"
+        else
+          "[#{link}](#{link})"
+        end
+      end
+
+      # Just reuse Textile special symbols for now?
+      Orgmode.special_symbols_to_textile(input)
+      input = @re_help.restore_code_snippets input
+      input
+    end
+
+    # TODO: Implement this
+    def output_footnotes!
+      return false
+    end
+
+    # Flushes the current buffer
+    def flush!
+      return false if @buffer.empty? and @output_type != :blank
+      @logger.debug "FLUSH ==========> #{@output_type}"
+      @buffer.gsub!(/\A\n*/, "")
+
+      case
+      when mode_is_code?(current_mode)
+        @output << "```#{@block_lang}\n"
+        @output << @buffer << "\n"
+        @output << "```\n"
+      when preserve_whitespace?
+        @output << @buffer << "\n"
+
+      when @output_type == :blank
+        @output << "\n"
+
+      else
+        case current_mode
+        when :paragraph
+          @output << "> " if @mode_stack[0] == :quote
+
+        when :list_item
+          @output << " " * @mode_stack.count(:list_item) << "* "
+
+        when :horizontal_rule
+          @output << "---"
+
+        end
+        @output << inline_formatting(@buffer) << "\n"
+      end
+      @buffer = ""
+    end
+
+    def add_line_attributes headline
+      @output << "#" * headline.level
+      @output << " "
+    end
+  end                           # class MarkdownOutputBuffer
+end                             # module Orgmode

lib/org-ruby/parser.rb

@@ -255,6 +255,18 @@ def to_textile
       output
     end
 
+    # Exports the Org mode content into Markdown format
+    def to_markdown
+      output = ""
+      output_buffer = MarkdownOutputBuffer.new(output)
+
+      translate(@header_lines, output_buffer)
+      @headlines.each do |headline|
+        translate(headline.body_lines, output_buffer)
+      end
+      output
+    end
+
     # Converts the loaded org-mode file to HTML.
     def to_html
       mark_trees_for_export