To give stronger type checking, I defined a type representing your yyyymmdd
values, created a declaration of that type, and used the type in the two
conversion functions. If your code isn't schema-aware, then you can
represent the yyyymmdd values simply as xs:string, which means you change
the two function signatures to use xs:string, and you no longer need the
schema, or the xsl:import-schema, to define the new type.
So it's perfectly possible to use the two conversion functions, and to do
the conversion using regular expressions, using a non-schema-aware
processor: the only thing you don't get is the free error checking.
Michael Kay
http://www.saxonica.com/
-----Original Message-----
From: cknell(_at_)onebox(_dot_)com [mailto:cknell(_at_)onebox(_dot_)com]
Sent: 18 May 2006 15:12
To: xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com
Subject: RE: RE: [xsl] XSLT 2.0/XPath 2.0 Date arithmetic
Permit me to parse your answer and ask additional questions.
I've already managed to munge the string into the proper
format with concat() and substring(), but this
<xsl:function name="f:to-iso-date" as="xs:date">
<xsl:param name="in" as="my:yyyymmdd-date"/>
<xsl:sequence select="xs:date(replace($in,
'(\d{4})(\d{2})(\d{2})', '$1-$2-$3'))"/> </xsl:function>
is appealing because of it's perl-ishness (yes, of course
perl incorporated existing concepts from UNIX shell utilities
like sed and awk, but I first encountered them when learning
perl), and because the function casts the return value to an xs:date.
In order to use this approach you suggest that I incorporate
an xsl:import-schema declaration in my stylesheet and use it
with either of the functions.
On the other hand, I'm using the non-schema-aware version of Saxon.
In reviewing the section on xsl:import-schema in "XSLT 2.0
Programmer's Reference" on page 324 I note that, "This
declaration is only available in a schema-aware processor."
So, how then would substituting " ... xs:string in place of
my:yyyymmdd-date ..." solve that issue?
I am puzzled by what appears to me as an inconsistency in the
answer which I must attribute to my weak grasp of the
subject. If I cannot use the suggested approach because my
processor is not schema-aware, is there some other native
XSLT 2.0 approach, or am I forced to use some extension function?
--
Charles Knell
cknell(_at_)onebox(_dot_)com - email
-----Original Message-----
From: Michael Kay <mike(_at_)saxonica(_dot_)com>
Sent: Thu, 18 May 2006 08:27:54 +0100
To: <xsl-list(_at_)lists(_dot_)mulberrytech(_dot_)com>
Subject: RE: [xsl] XSLT 2.0/XPath 2.0 Date arithmetic
Given a parameter, let's call it "today" in the form of this
string "20060517", how do I create a variable, let's call it
"tMinus1" such that it represents a day earlier than
"20060517", that would be "20060516". So long as "$today"
isn't the first day of a month, a simple subtraction and
followed by a type cast that I don't grasp would do the trick.
What I'm looking for is guidance on date arithmetic.
You'd be much better off working with the xs:date type, which uses the
format 2006-05-17.
So, two functions to convert between your non-standard dates
and standard
xs:date objects:
<xsl:import-schema>
<xs:schema target-namespace="http://my-date";>
<xs:simpleType name="yyyymmdd-date">
<xs:restriction base="xs:string">
<xs:pattern value="[0-9]{4}[0-1][0-9][0-3][0-9]"/>
</
</
</
</
<xsl:function name="f:to-iso-date" as="xs:date">
<xsl:param name="in" as="my:yyyymmdd-date"/>
<xsl:sequence select="xs:date(replace($in, '(\d{4})(\d{2})(\d{2})',
'$1-$2-$3'))"/>
</xsl:function>
<xsl:function name="f:to-yyyymmdd-date" as="my:yyyymmdd-date">
<xsl:param name="in" as="xs:date"/>
<xsl:sequence
select="my:yyyymmdd-date(translate(string($in, '-', ''))"/>
</xsl:function>
then:
select="f:to-yyyymmdd-date(f:to-iso-date($input-date) -
xs:dayTimeDuration('PT1D'))"
If you're not schema-aware, then use xs:string in place of
my:yyyymmdd-date
- all you lose is type-checking.
Michael Kay
http://www.saxonica.com/
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