# Hpricot test for equivalence of two xml segments? **URL:** \ **Category:** Ruby\ **Created:** [July 16, 2010, 11:39pm UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731 "2010-07-16T23:39:48Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/a9a28c/32.png) [@Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/u/Xeno_CSS_Eskimo_No)\ **Post date:** [July 16, 2010, 11:39pm UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731/1 "2010-07-16T23:39:48Z")
I’m looking through what documentation I can find for Hpricot (nokogirl wouldn’t install for me, and I just wand a quick an simple solution), and I cannot find a simple method to take two xml strings and find out if they are equivalent. I’m getting a bunch of xhmtl back from our rendering agent with random permutations of attributes inside of the tags, and I want a quick and easy ruby way to find out of segments are equivalent without writing my own regex based parser…??? It seems like there should be a simple method for this. If I had written Hpricot, equivalence of segments would have been the first method I would have written…??? xc ---
**Author:** ![Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/a9a28c/32.png) [@Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/u/Xeno_CSS_Eskimo_No)\ **Post date:** [July 17, 2010, 12:17am UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731/2 "2010-07-17T00:17:16Z")
On Sat, Jul 17, 2010 at 12:28 AM, Xeno C. / Eskimo North and Gmail \< removed\_email\_address@domain.invalid\> wrote: > I’m looking through what documentation I can find for Hpricot (nokogirl > wouldn’t install for me, and I just wand a quick an simple solution), and I > cannot find a simple method to take two xml strings and find out if they are > equivalent. I’m getting a bunch of xhmtl back from our rendering agent with > random permutations of attributes inside of the tags, and I want a quick and > easy ruby way to find out of segments are equivalent without writing my own > regex based parser…??? I can think of a few definitions for equivalence. One definition would simply require unifying the case of both strings and checking if they are the same. A second definition would require building a tree of the structure in each string, including attributes, sorting it, and looping over them to check if they contain the same elements (Nokogiri’s XML::NodeSet does something like this with ==). A third definition would build on the second one, while treating certain tags as equivalent to other tags (for example q is equivalent to blockquote). What’s _your_ definition of equivalence for two xml documents or fragments? Ammar ---
**Author:** ![Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/a9a28c/32.png) [@Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/u/Xeno_CSS_Eskimo_No)\ **Post date:** [July 17, 2010, 12:52am UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731/3 "2010-07-17T00:52:58Z")
On 10-07-16 03:16 PM, Ammar A. wrote: > What’s _your_ definition of equivalence for two xml documents or fragments? > > Ammar The only thing I am concerned about is permutations of attributes inside the tags. Everything else I’m seeing is regular. Is there something where I can parse all the tags in a segment and tell if they are equivalent and just have the attributes in different orders? I’m not even concerned about different tag forms. We don’t see that. A typical example is: \< - ![alt text](https://www.ruby-forum.com/my/image/path/thingy.jpg)My Text > - ![alt text](https://www.ruby-forum.com/my/image/path/thingy.jpg)My Text I need to have something that can help me judge such things as equivalent. Again, I NEVER see tag permutations, but just attribute permutations. > Thank you for you response. Sincerely, Xeno ---
**Author:** ![Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/a9a28c/32.png) [@Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/u/Xeno_CSS_Eskimo_No)\ **Post date:** [July 17, 2010, 1:27am UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731/4 "2010-07-17T01:27:31Z")
On Fri, Jul 16, 2010 at 6:52 PM, Xeno C. / Eskimo North and Gmail \< removed\_email\_address@domain.invalid\> wrote: > > > equivalent. I’m getting a bunch of xhmtl back from our rendering agent > > > simply require unifying the case of both strings and checking if they are > > > fragments? > > > \< > > > > > > - ![alt text](https://www.ruby-forum.com/my/image/path/thingy.jpg)My Text > > > > - ![alt text](https://www.ruby-forum.com/my/image/path/thingy.jpg)My Text > > I need to have something that can help me judge such things as equivalent. > Again, I NEVER see tag permutations, but just attribute permutations. You should take a look at Lorax: > **[GitHub - flavorjones/lorax: XML/HTML diff generator, based on Nokogiri.](https://github.com/flavorjones/lorax)** > > XML/HTML diff generator, based on Nokogiri. Contribute to flavorjones/lorax development by creating an account on GitHub. which is Nokogiri-based. Your definition of equivalence (the semantically correct one, imho) can be tested with: ``` Lorax::Signature.new(Nokogiri::XML(string1).root).signature == ``` Lorax::Signature.new(Nokogiri::XML(string2).root).signature And note that Nokogiri will also alllow you to parse XML fragments. HTH, -m ---
**Author:** ![Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/a9a28c/32.png) [@Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/u/Xeno_CSS_Eskimo_No)\ **Post date:** [July 17, 2010, 2:03am UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731/5 "2010-07-17T02:03:48Z")
> > Again, I NEVER see tag permutations, but just attribute permutations. I believe you. Nokogirl wouldn’t install though…yes, and nor did Lorax… Looks like there’s an install site, but I hesitate to use something this outside the mainstream on a project like this. I don’t want to impose needless maintenance problems on my environment. ---
**Author:** ![Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/x/a9a28c/32.png) [@Xeno\_CSS\_Eskimo\_No](https://www.ruby-forum.com/u/Xeno_CSS_Eskimo_No)\ **Post date:** [July 17, 2010, 3:15am UTC](https://www.ruby-forum.com/t/hpricot-test-for-equivalence-of-two-xml-segments/191731/6 "2010-07-17T03:15:47Z")
On Sat, Jul 17, 2010 at 09:03:21AM +0900, Xeno C. / Eskimo North and Gmail wrote: > > > I need to have something that can help me judge such things as equivalent. > > > Again, I NEVER see tag permutations, but just attribute permutations. > > I believe you. Nokogirl wouldn’t install though…yes, and nor did Lorax… Do you mind emailing our list with the problems? We do our best to make sure that nokogiri works on most systems, so if you’re having trouble we’d love to hear about it: [http://groups.google.com/group/nokogiri-talk](http://groups.google.com/group/nokogiri-talk) > Looks like there’s an install site, but I hesitate to use something > this outside the mainstream on a project like this. I don’t want to > impose needless maintenance problems on my environment. I’m not sure that nokogiri is outside the mainstream. Take a look at our gem downlods vs the hpricot gem downloads: [nokogiri | RubyGems.org | your community gem host](http://rubygems.org/gems/nokogiri) [hpricot | RubyGems.org | your community gem host](http://rubygems.org/gems/hpricot) Or the frequency of commits: [http://github.com/tenderlove/nokogiri/commits/master](http://github.com/tenderlove/nokogiri/commits/master) [Commits · hpricot/hpricot · GitHub](http://github.com/hpricot/hpricot/commits/master) Or the mailing list activity: [http://groups.google.com/group/nokogiri-talk](http://groups.google.com/group/nokogiri-talk) [http://librelist.com/browser/hpricot/](http://librelist.com/browser/hpricot/) But “mainstream” is a judgement is for you to make! 🙂