gistfile1.rb

# from http://pastie.org/426366
require 'hpricot'

module Webby
  class Renderer
    attr_reader :page
  end

  module Filters
    # To use: add relpath to the end of the list of filters in the layout. It won't
    # work in the content file itself.
    # add it to the css directly, since it doesn't have a layout and is processed in
    # a special way
    class RelPath
      def initialize( str, mode, path )
        @str = str
        @mode = mode.downcase.to_sym
        dir = File.dirname(path)
        depth = 0
        while (parent = File.dirname(dir)) != dir
          dir = parent
          depth += 1
        end
        depth -= 1 # because of the 'content/' prefix
        @prefix = "../" * depth
      end

      def filter
        if @mode == :css
          # matches url attributes like: url("/images/test.gif")
          # and replaces it with: url("../images/test.gif")
          # if the css file is in css/some.css
          # no clue about the xpaths, should read up about that :(
          doc = @str.gsub(/(url\(")\/(.*)("\))/) do |s|
            "#{$1}#{@prefix}#{$2}#{$3}"
          end
          doc
        else
          doc = @mode == :xml ? Hpricot.XML(@str) : Hpricot(@str)
          attr_rgxp = %r/\[@(\w+)\]$/o
          sub_rgxp = %r/\A\//o # <-- note this rgxp _consumes_ the "/"

          ::Webby.site.xpaths.each do |xpath|
            @attr_name = nil
            doc.search(xpath).each do |element|
              @attr_name ||= attr_rgxp.match(xpath)[1]
              a = element.get_attribute(@attr_name)
              element.set_attribute(@attr_name, a) if a.sub!(sub_rgxp, @prefix)
            end
          end
          doc.to_html
        end
      end
    end

    register :relpath do |input, cursor|
      RelPath.new(input, cursor.page.extension, cursor.renderer.page.path).filter
    end
  end  # module Filters
end  # module Webby