W3C home > Mailing lists > Public > public-qt-comments@w3.org > April 2005

fn:escape-uri needs to be invertible in the true() case; take out the % exception

From: Dan Connolly <connolly@w3.org>
Date: Fri, 08 Apr 2005 17:09:07 -0500
To: public-qt-comments@w3.org
Message-Id: <1112998147.15813.106.camel@localhost>

Regarding...

"Generally, $escape-reserved should be set to true when escaping a
string that is to form a single part of a URI, and to false when
escaping an entire URI or URI reference."
http://www.w3.org/TR/2005/WD-xpath-functions-20050404/#func-escape-uri

Indeed, those are the two relevant tasks. I might prefer
separate functions, as the tasks are quite unrelated.
In any case, the exception for the % character makes this
function unsuitable for the task of "form[ing] a single part of a URI".

As specified, fn:escape-uri("gross %each") returns "gross%20%each"
but that doesn't actually encode the string "gross %each" into
part of a URI such that the party that encoded it can decode it
again. In order to be useful, it needs to return
'gross%20%25each' . It needs to be invertible.

i.e. XQuery should follow all the other programming languages
out there, such as

- python
 http://docs.python.org/lib/module-urllib.html

>>> urllib.quote("gross %each")
'gross%20%25each'

- perl

perl -e 'use URI::Escape; print uri_escape("gross %each"), "\n"'
gross%20%25each

http://www.gsp.com/cgi-bin/man.cgi?section=3&topic=URI::Escape

- javascript

http://www.javascripter.net/faq/escape.htm

I can't find the standard library functions for Java and C#
with a few minutes of googling, but I'll bet they work likewise.

p.s. yes, this is essentially the same comment I made back in 2003.
http://lists.w3.org/Archives/Public/uri/2003Mar/0027.html

-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
D3C2 887B 0F92 6005 C541  0875 0F91 96DE 6E52 C29E
Received on Friday, 8 April 2005 22:09:09 GMT

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