如何解析XML Nokogiri中的全文？

Question

foo = <root>
<m>This is <b>bold</b> and <i>
<b>italic<br/>text</b></i>.<br/></m>
</root>

doc  = Nokogiri::XML foo
doc.xpath("//m").each {|a|
  a.children.each{|v|
   puts "#{v.name}::[#{v.text}]"
  }
}

如何解析<m>内所有标签中的所有文字？

我需要产生以下输出......

t="This is "
b="bold"
t=" and "
i=""
b="italic"
br="<br/>"
t="text"

...

等

https://gist.github.com/anonymous/e98fb4e4c254883a17a2

#!/usr/bin/env ruby
# encoding: utf-8
require 'nokogiri'

foo = <<-EOXML
<root>
 <m>This   is <b>bold</b> and <i><b>italic<br/>text</b></i>.<br/></m>
</root>
EOXML

def pr(v)
 case v.class.to_s
  when 'Nokogiri::XML::Text'
   puts "[#{v.text}]"
  when 'Nokogiri::XML::Element'
   puts "'#{v.name.to_s}':: #{pr(v.children)}"
  when 'Nokogiri::XML::NodeSet'
   puts "#{v.children}"
  else
   puts "[-#{v.class.to_s}- #{v.to_s}]"
  end
end

doc  = Nokogiri::XML.parse foo
p foo
doc.xpath("//m").each {|a|
  a.children.each{|v|
   puts "#{v.name}::[#{v.text}]"
  }
}

如何更改上面的代码以便它使用递归？