string_replacer.rb

require 'nokogiri'

module Modulor
  
  # Performs gsub while ignoring HTML tags and their attributes.
  #
  # Usage:
  # repl = Modulor::StringReplacer.new('<a href="/en/Foo" class="foo">foo</a>')
  # repl.gsub(/foo/i, 'bar')
  # repl.to_html => '<a href="/en/Foo" class='foo'>bar</a>'
  
  class StringReplacer

    def initialize html_fragment
      @html_fragment = html_fragment.to_s
      @doc = Nokogiri::HTML::DocumentFragment.parse(@html_fragment)
    end

    # ---------------------------------------------------------------------
      
    def to_s
      @doc.to_s
    end

    def to_html
      @doc.to_html
    end

    # ---------------------------------------------------------------------
    
    def gsub from, to
      return unless from.present?
      @doc.xpath('.//*').each do |node|
        node.inner_html = node.inner_html.gsub(from, to)
      end
    end

  end
end