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RE: [xsl] Calling mutator java method (date fields to seconds-since-epoch with java.util.GregorianCalendar)
2006-08-22 06:21:45
Flipping through Appendix B of MK's XSLT 2.0 book, my best
guess would be to create two
dateTimes: one with my string date fields and one of 1970.
Then I could use subtract-dates/dateTimes... to get an
xdt:*Duration. But if I had the duration, how would I convert
it into the number of seconds?
<xsl:variable name="origin" select="xs:dateTime('1970-01-01T00:00:00')"/>
<xsl:variable name="one-ms" select="xs:dayTimeDuration('PT0.001S')"/>
<xsl:function name="f:milliseconds-since-origin" as="xs:integer">
<xsl:param name="in" as="xs:dateTime"/>
<xsl:sequence select="xs:integer(($in - $origin) div $one-ms)"/>
</xsl:function>
Seem a lot simpler than the Java GregorianCalendar class...
Michael Kay
http://www.saxonica.com/
Despite my best efforts, I have not found a reasonable
introduction to the xs/xdt typing system. Does anyone have
any suggestions for references?
Regards,
Tim
On 8/22/06, Michael Kay <mike(_at_)saxonica(_dot_)com> wrote:
The way extension functions work is to a large extent
implementation-defined, so it's fairly meaningless to ask questions
about them without saying what XSLT processor you are using.
In general, though, calling extension functions with
side-effects is
likely to be problematic, as the calls can easily be optimized away.
If this is Saxon, for example, a variable that's never
referenced will
never be evaluated. And variables that are used will usually be
evaluated in a different order from the order in which they
are declared.
With Saxon you can usually ensure that a void extension function is
called by including the call in an xsl:value-of instruction that is
writing to the result tree. Saxon deliberately avoids
looking at the
function signature to discover that the method always returns void,
instead treating it as if the returned result might be significant.
But if you're using Saxon, why not do the calculation in XPath?
Michael Kay
http://www.saxonica.com/
-----Original Message-----
From: Tim Lebo [mailto:timleboxslt(_at_)gmail(_dot_)com]
Sent: 22 August 2006 02:35
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: [xsl] Calling mutator java method (date fields to
seconds-since-epoch with java.util.GregorianCalendar)
Hello,
I need to determine the number of seconds past the epoch
given the
year, month, day, hour, and minute fields (as strings).
This can be done with the java.util.GregorianCalendar class using
the
set(year,month,day,hour,minute) mutator and calling the
getTimeInMillis() accessor. I have been able to
demonstrate this in
a sample main class that uses GregorianCalendar:
// For year,month,day,hour,min -> seconds
since epoch
import java.util.Calendar;
import java.util.GregorianCalendar;
public class MyDate {
public static void main(String args[]) {
Calendar myCal = new
GregorianCalendar();
myCal.set(2006,7,21,13,26,0);
//1156181207
System.out.println(myCal.getTimeInMillis()/1000 - 1156181207);
}
}
The following xslt shows how I instantiate a
GregorianCalendar. Two
outputs are obtained:
1) A failed attempt to get the seconds-since-the-epoch
after the set
method call
2) The objects toString, which shows that the date information is
actually the time of execution and not the date set
This leads me to believe that the mutator call did not
'take effect'.
Looking to previous java-interaction solutions that I
have created,
I notice that this is the first time I am calling an object's
mutator method, which returns void. Does this need to be handled
differently?
Regards,
Tim
<xsl:transform version="2.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform";
xmlns:xfm="transform namespace"
xmlns:xs="http://www.w3.org/2001/XMLSchema";
xmlns:cal="java:java.util.GregorianCalendar"
exclude-result-prefixes="xfm xs">
<xsl:output method="text"/>
<xsl:template match="/">
<xsl:variable name="start" select="cal:new()"/>
<xsl:variable name="start-set"
select="cal:set($start,xs:integer('2006'),
xs:integer('7'),xs:integer('21'),
xs:integer('13'),xs:integer('26'),xs:integer('0'))"/>
<xsl:value-of select="concat('expecting
seconds-since-epoch of
2006
21 Aug at 13:26:00, but getting current
seconds-since-epoch: ',$NL,
xs:integer(cal:getTimeInMillis($start))
div xs:integer('1000'),$NL,$NL)"/>
<xsl:value-of select="concat('toString indicates
that the call
to set the date was not recognized (See
DAY_OF_MONTH,HOUR_OF_DAY...):',$NL,
cal:toString($start),$NL)"/>
</xsl:template>
<xsl:variable name="NL">
<xsl:text>
</xsl:text>
</xsl:variable>
</xsl:transform>
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