Re: [xsl] Function converting RFC 2822 date to xsd:dateTime

The main question about error handling here is how liberal you want to be, e.g. 
do you want to fail on "Wed 9 Apr 2019" on the grounds that 9 April isn't a 
Wednesday? Similarly, do you want to validate leap years etc? As far as I can 
see, you're allowing 31 Apr but not 32 Apr, and that seems a bit pointless to 
me.

The secondary point is what you do when invalid input is detected. If you want 
to do a hard fail then xsl:message terminate="yes" is as good as anything.

Also, I can't work out what you're trying to do with timezones.

Michael Kay
Saxonica

> On 8 Apr 2019, at 23:32, Martynas Jusevičius 
> martynas(_at_)atomgraph(_dot_)com 
> <xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
>
> Thanks Michael, I will have parse-ietf-date() in mind.
>
> As for invalid values, the template invoking the function should
> handle the error with some kind of conditional and skip creating
> content with such values.
>
> How would such error handling look like? Preferably in XSLT 2.0, but
> I'm also interested in how it would compare to XSLT 3.0.
>
> I was reading about the error() function in relation to this, but
> couldn't figure out how exactly it could be used here.
>
> On Tue, Apr 9, 2019 at 12:16 AM Michael Kay mike(_at_)saxonica(_dot_)com
> <xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
> > Are you aware that XPath 3.0 has the function parse-ietf-date() for this?
> >
> > https://www.w3.org/TR/xpath-functions-31/#func-parse-ietf-date
> >
> > The Saxon implementation is in Java; I haven't attempted an XPath 
> > implementation. But you might find the spec (and the associated notes) is 
> > useful in itself; and of course the QT3 test suite has test cases.
> >
> > I don't know how date/times in RFC 2822 relate to all the other 
> > miscellaneous RFCs referenced in the spec. Liam Quin did most of the 
> > research for this.
> >
> > What are your requirements for handling invalid values?
> >
> > Michael Kay
> > Saxonica
> >
> > > On 8 Apr 2019, at 22:58, Martynas Jusevičius 
> > > martynas(_at_)atomgraph(_dot_)com 
> > > <xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
> > >
> > > Hi,
> > >
> > > I have an XSLT 2.0 task where I'm parsing email Date headers defined
> > > in RFC 2822 and converting them to xsd:dateTime.
> > >
> > > Below is a function that converts between the two. I wanted to hear if
> > > there are improvements that could be made?
> > >
> > >   <xsl:function name="aex:rfc2822dateTime-to-dateTime" as="xs:dateTime">
> > >       <xsl:param name="date-time" as="xs:string"/> <!-- Tue, 9 Apr
> > > 2019 00:07:24 +1200 (NZST) -->
> > >       <xsl:variable name="months" select="'Jan', 'Feb', 'Mar',
> > > 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'"
> > > as="xs:string*"/>
> > >       <xsl:analyze-string select="$date-time"
> > >           
> > > regex="^(?:(Sun|Mon|Tue|Wed|Thu|Fri|Sat),\s+)?(0[1-9]|[1-2]?[0-9]|3[01])\s+(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+(19[0-9]{{2}}|[2-9][0-9]{{3}})\s+(2[0-3]|[0-1][0-9]):([0-5][0-9])(?::(60|[0-5][0-9]))?\s+([-\+][0-9]{{2}}[0-5][0-9]|(?:UT|GMT|(?:E|C|M|P)(?:ST|DT)|[A-IK-Z]))(\s+|\(([^\(\)]+|\\\(|\\\))*\))*$">
> > >           <xsl:matching-substring>
> > >               <xsl:sequence
> > > select="xs:dateTime(concat(format-number(xs:integer(regex-group(4)),
> > > '0001'), '-', format-number(index-of($months, regex-group(3)), '01'),
> > > '-', format-number(xs:integer(regex-group(2)), '01'), 'T',
> > > format-number(xs:integer(regex-group(5)), '01'), ':',
> > > format-number(xs:integer(regex-group(6)), '01'), ':',
> > > format-number(xs:integer(regex-group(7)), '01'),
> > > substring(regex-group(8), 1, 3), ':', substring(regex-group(8), 4,
> > > 2)))"/>
> > >           </xsl:matching-substring>
> > >           <xsl:non-matching-substring>
> > >               <xsl:message>Invalid RFC 2822 datetime: <xsl:value-of
> > > select="$date-time"/></xsl:message>
> > >           </xsl:non-matching-substring>
> > >       </xsl:analyze-string>
> > >   </xsl:function>
> > >
> > > The regex pattern is taken from
> > > https://stackoverflow.com/questions/9352003/rfc-2822-date-regex
> > >
> > > Martynas
> > > atomgraph.com
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