Markdownの目次を作るスクリプト

gen-toc.rb

#!/usr/bin/env ruby

TITLE_REGEXP = /(#+) (.+)/

text = File.read(ARGV[0]).split("\n")

numbers = []
counts = Array.new(6){ 0 }
prev_level = 0
text.each do |line|
  TITLE_REGEXP.match(line) do |m|
    level = m[1].size - 2
    content = m[2]

    if level < prev_level
      (level + 1).upto(prev_level) do |i|
        counts[i] = 0
      end
    end

    next if level < 0 # top level

    counts[level] += 1

    number = counts.take(level + 1).join('.')
    numbers << number
    puts "* [#{number} #{content}](#anchor#{number})"

    prev_level = level
  end
end

puts

text.each do |line|
  is_title = TITLE_REGEXP.match(line) do |m|
    level = m[1].size
    if level == 1
      puts line
    else
      number = numbers.shift
      puts <<-EOS
<a id="anchor#{number}"></a>
#{m[1]} <a href="#anchor#{number}">#{m[2]}</a>
      EOS
    end
    true
  end

  unless is_title
    puts line
  end
end