Webby filter to create paths readable by the file system for CHM and Mac help bundles

localpath.rb

module Webby
class Renderer
  attr_reader :page
end

module Filters

# To use add localpath to the end of the list of filters in the layout.
# Converts all links starting with '/' to use relative paths and appends
# 'index.html' to all links both starting and ending with '/'.
class LocalPath
  def initialize( str, dir )
    @str = str
    @dir = dir
  end
  
  def rel_path(base, path)
  	base.gsub!(/\\/,'/')
  	path.gsub!(/\\/,'/')
  	base = base.split('/')
  	path = path.split('/')
  	i = 0
  	while ((base[i] == path[i]) && (i < base.size))
  	i += 1
  	end
  	'../'*(base.size - i) + path[i..-1].join('/')
  end

  def filter
    rgxp = %r/="\/([^"]*)"/
    
    @str.gsub!(rgxp) do
      path = $1
      path << "index.html" if path[-1,1] == '/' || path.empty?
      path = rel_path(@dir, path)
      %Q(="#{path}")
    end
  end
end

register :localpath do |input, cursor|
  LocalPath.new(input, cursor.renderer.page.dir).filter
end

end  # module Filters
end  # module Webby