Class: ReverseMarkdown

Inherits:
Object
  • Object
show all
Defined in:
lib/google/reverse-markdown/reverse_markdown.rb

Overview

TODO

  • ol numbering is buggy, in fact doesn’t matter for markdown code

-

Instance Method Summary collapse

Constructor Details

#initialize ⇒ ReverseMarkdown

set basic variables:

  • @li_counter: numbering list item (li) tags in an ordered list (ol)

  • @links: hold the links for adding them to the bottom of the @output

    this means 'reference style', please take a look at http://daringfireball.net/projects/markdown/syntax#link

  • @outout: fancy markdown code in here!

  • @indent: control indention level for nested lists

  • @errors: appearing errors, like unknown tags, go into this array



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 27

def initialize()
  @li_counter = 0
  @links = []
  @output = ""
  @indent = 0
  @errors = []
end

Instance Method Details

#ending(type, parent) ⇒ Object

Returns the closing markdown tag, like opening()



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 135

def ending(type, parent)
  case type.name.to_sym
    when :h1
      " #\n\n"
    when :h2
      " ##\n\n"
    when :h3
      " ###\n\n"
    when :h4
      " ####\n\n"
    when :h5
      " #####\n\n"
    when :h6
      " ######\n\n"
    when :p
      parent.eql?(:root) ? "\n\n" : "\n"
    when :ol
      parent.eql?(:li) ? "" : "\n"
    when :ul
      parent.eql?(:li) ? "" : "\n"
    when :em
      "*"
    when :strong
      "**"
    when :li
      ""
    when :blockquote
      ""
    when :code
      parent.eql?(:pre) ? "" : "`"
    when :a
      @links << type.attribute('href').to_s
      "][" + @links.size.to_s + "] "
    when :img
      @links << type.attribute('src').to_s
      "" + type.attribute('alt').to_s + "][" + @links.size.to_s + "] "
      "#{type.attribute('alt')}][#{@links.size}] "
    when :root
      ""
    else
      @errors << "  unknown end tag: "+type.name.to_s
      ""
  end
end

#indent ⇒ Object

Perform indent: two space, @indent times - quite simple! :)



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 181

def indent
  str = ""
  @indent.times do
    str << "  "
  end
  str
end

#insert_links ⇒ Object

Insert the mentioned reference style links.



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 203

def insert_links
  @output << "\n"
  @links.each_index do |index|
    @output << "  [#{index+1}]: #{@links[index]}\n"
  end
end

#opening(type, parent) ⇒ Object

Returns opening markdown tag for the element. Its parent matters sometimes!



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 89

def opening(type, parent)
  case type.name.to_sym
    when :h1
      "# "
    when :li
      parent.eql?(:ul) ? " - " : " "+(@li_counter+=1).to_s+". "
    when :ol
      @li_counter = 0
      ""
    when :ul
      ""
    when :h2
      "## "
    when :h3
      "### "
    when :h4
      "#### "
    when :h5
      "##### "
    when :h6
      "###### "
    when :em
      "*"
    when :strong
      "**"
    when :blockquote
      # remove leading newline
      type.children.first.value = ""
      "> "
    when :code
      parent.eql?(:pre) ? "    " : "`"
    when :a
      "["
    when :img
      "!["
    when :hr
      "----------\n\n"
    when :root
      ""
    else
      @errors << "unknown start tag: "+type.name.to_s
      ""
  end
end

#parse_element(element, parent) ⇒ Object

Parsing an element and its children (recursive) and writing its markdown code to @output

  1. do indent for nested list items

  2. add the markdown opening tag for this element

3a. if element only contains text, handle it like a text node 3b. if element is a container handle its children, which may be text- or element nodes

  1. finally add the markdown ending tag for this element



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 51

def parse_element(element, parent)
  name = element.name.to_sym
  # 1.
  @output << indent() if name.eql?(:li)
  # 2.
  @output << opening(element, parent)

  # 3a.
  if (element.has_text? and element.children.size < 2)
    @output << (text_node(element, parent) || '')
  end

  # 3b.
  if element.has_elements?
    element.children.each do |child|
      # increase indent if nested list
      @indent += 1 if element.name=~/(ul|ol)/ and parent.eql?(:li)

      if child.node_type.eql?(:element)
        parse_element(child, element.name.to_sym)
      else
        if parent.eql?(:blockquote)
          @output << child.to_s.gsub("\n ", "\n>")
        else
          @output << child.to_s
        end
      end

      # decrease indent if end of nested list
      @indent -= 1 if element.name=~/(ul|ol)/ and parent.eql?(:li)
    end
  end

  # 4.
  @output << ending(element, parent)
end

#parse_string(string) ⇒ Object

Invokes the HTML parsing by using a string. Returns the markdown code in @output. To garantuee well-formed xml for REXML a <root> element will be added, but has no effect. After parsing all elements, the ‘reference style’-links will be inserted.



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 38

def parse_string(string)
  doc = Document.new("<root>\n"+string.encode("UTF-8")+"\n</root>")
  parse_element(doc.root, :none)
  insert_links()
  @output
end

#print_errors ⇒ Object

Print out all errors, that occured and have been written to @errors.



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 211

def print_errors
  @errors.each do |error|
    puts error
  end
end

#speed_benchmark(string, n) ⇒ Object

Perform a benchmark on a given string n-times.



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 218

def speed_benchmark(string, n)
  initialize()
  bm(15) do |test|
    test.report("reverse markdown:")    { n.times do; parse_string(string); initialize(); end; }
  end
end

#text_node(element, parent) ⇒ Object

Return the content of element, which should be just text. If its a code block to indent of 4 spaces. For block quotation add a leading ‘>’



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# File 'lib/google/reverse-markdown/reverse_markdown.rb', line 192

def text_node(element, parent)
  if element.name.to_sym.eql?(:code) and parent.eql?(:pre)
    element.text.gsub("\n","\n    ") << "\n"
  elsif parent.eql?(:blockquote)
    element.text.gsub!("\n ","\n>")
  else
    element.text
  end
end