From: William James <w_a_x_man@...>
Date: 2006-02-23T13:08:32+09:00
Subject: Re: Xpath to attributes

listrecv@gmail.com wrote:
> Is there anyway to do generic xpath's, for both elements and attributes
> (ie //customer/phone/@type --> "home")?  REXML can do xpath to fetch
> elements (rexml_element.text('//customer/phone')) but can't seem to use
> xpath to find attributes.

class Array; alias atr first; alias txt last  end
class String
  def xtag(s)
    scan( %r!
              < #{s}  (?: \s+ (  [^>]*  )  )? / >
              |
              < #{s}  (?: \s+ (  [^>]*  )  )? >
              ( .*? )  </ #{s} >
          !mx ).
      map{ |unpaired, attr, data|   h = { }
        attr = ( unpaired || attr )
        if attr
          attr.scan( %r!  ( \S+ ) = ( ["'] ) ( .*? ) \2  !x ){ |k,q,v|
            h[k] = v }
        end
        [ h, data ]
      }
  end
  def xpath(s)
    s.scan(%r! [^/"]+ (?: "[^"]*" )? !x).inject([[nil,self]]){|ary,str|
      if "@" == str[0,1]
        str =~ /@(.*?)="(.*)"/
        ary.select{|a,t| a[$1] == $2 }
      else
        return []  if [] == ary
        ary[0].txt.xtag(str)
      end
    }
  end
end


p DATA.read.xpath('customer/@loc="south"/phone/@type="mobi"')


__END__
<customer loc="north">
  <phone type='home'>0115</phone>
  <phone type='mobi'>07807</phone>
</customer>
<customer loc="south">
  <phone type='home'>0319</phone>
  <phone type='mobi'>09802</phone>
</customer>