From: Robert Klemme <shortcutter@...>
Date: 2008-11-03T19:39:55+09:00
Subject: Re: Using XPath: find last text node of each paragraph under the root node.

2008/11/3 Diego <diego@heyboyo.com>:
> I want to trim trailing whitespace at the end of all XHTML paragraphs.
> I am using the REXML library.
>
> Say I have the following in a valid XHTML file:
>
> <p>hello <span>world</span> a </p>
> <p>Hi there </p>
> <p>The End </p>
>
> I want to end up with this:
>
> <p>hello <span>world</span> a</p>
> <p>Hi there</p>
> <p>The End</p>
>
> So I was thinking what I could use XPath to get just the text nodes
> that I want, then just trim the text, which would allow me to end up
> with what I want (previous).
>
> I started with the following XPath: //root/p/child::text()
>
> Of course, the problem here is that it returns all text nodes that are
> children of all p-tags. Which is this:
>
> 'hello '
> ' a '
> 'Hi there '
> 'The End '
>
> Trying the following XPath gives me the last text node of the last
> paragraph. Not the last text node of each paragraph that is a child of
> the root node.
>
> //root/p/child::text()[last()]
>
> This only returns: 'The End '
>
> What I would like to get from the XPath is therefore:
>
> ' a '
> 'Hi there '
> 'The End '
>
> I have tried //root//p/child::text()[last()] on other XPath parsers,
> and it works. Could just be a bug (or different interpretation of the
> rules) by REXML?

Could well be both.  When I try '//p/text()[last()]' I get only the
last node of the whole document. The issue seems to be the binding of
last() i.e. which collection it references or when it is applied. I
lean towards the bug variant.

One workaround would be to use a two step approach, i.e. first select
all <p> and then the last text:

irb(main):062:0> doc.elements.each('//p'){|x|
REXML::XPath.each(x,'text()[last()]'){|t|p t}}
" a "
"Hi there "
"The End "
=> [<p> ... </>, <p> ... </>, <p> ... </>]

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end