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XSLT associative arrays

 
 
Eric Anderson
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      10-08-2004
Got a quick question trying to figure out the XSLT way of implementing
the functionality of associative arrays. Basically want I want to do is
the following:

<xsl:template name="foo">
<xslaram name="bar"/>
<xsl:choose>
<xsl:when test="$bar = 'a'">b</xsl:when>
<xsl:when test="$bar = 'c'">d</xsl:when>
<xsl:when test="$bar = 'e'">f</xsl:when>
....
...
..
..
<xsl:choose>
<xsl:template>

Now imagine bar is could be one of a hundred values. Also imagine that
we are not just printing out a simple value. Imagine we have some
complex code that just uses that simple value. We don't want to
continually repeat that complex code all down the page. So what I would
really like is something like:

<xsl:variable name="a" select="'b'"/>
<xsl:variable name="c" select="'d'"/>
<xsl:variable name="e" select="'f'"/>
<xsl:variable name="g" select="'h'"/>
.....
....
...


<xsl:template name="foo">
<xslaram name="bar">
<xsl:value-of select="${$bar}"/>
</xsl:template>

What I am trying to indicate here is that $bar is resolved to 'a', 'c',
'e', 'g' or any other sort of value. Then that value is used as a
variable to resolve to 'b', 'd', 'f', 'h' or any other sort of
associated variable. Now obviously my made up syntax doesn't work. My
question is what is the proper way to do this in XSLT? Basically how do
you create and use an associative array in XSLT? This would all be
equivalent to the following in Perl.

baz{a} = 'b';
baz{c} = 'd';
baz{e} = 'f';
baz{g} = 'h';
.....
....
...

sub foo {
my ( $bar ) = @_;
print $baz{$bar};
}

Any suggestions?

Eric

 
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Philippe Poulard
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      10-08-2004
Eric Anderson wrote:
> Got a quick question trying to figure out the XSLT way of implementing
> the functionality of associative arrays. Basically want I want to do is
> the following:
>
> <xsl:template name="foo">
> <xslaram name="bar"/>
> <xsl:choose>
> <xsl:when test="$bar = 'a'">b</xsl:when>
> <xsl:when test="$bar = 'c'">d</xsl:when>
> <xsl:when test="$bar = 'e'">f</xsl:when>
> ....
> ...
> ..
> ..
> <xsl:choose>
> <xsl:template>
>
> Now imagine bar is could be one of a hundred values. Also imagine that
> we are not just printing out a simple value. Imagine we have some
> complex code that just uses that simple value. We don't want to
> continually repeat that complex code all down the page. So what I would
> really like is something like:
>
> <xsl:variable name="a" select="'b'"/>
> <xsl:variable name="c" select="'d'"/>
> <xsl:variable name="e" select="'f'"/>
> <xsl:variable name="g" select="'h'"/>
> ....
> ...
> ..
>
>
> <xsl:template name="foo">
> <xslaram name="bar">
> <xsl:value-of select="${$bar}"/>
> </xsl:template>
>
> What I am trying to indicate here is that $bar is resolved to 'a', 'c',
> 'e', 'g' or any other sort of value. Then that value is used as a
> variable to resolve to 'b', 'd', 'f', 'h' or any other sort of
> associated variable. Now obviously my made up syntax doesn't work. My
> question is what is the proper way to do this in XSLT? Basically how do
> you create and use an associative array in XSLT? This would all be
> equivalent to the following in Perl.
>
> baz{a} = 'b';
> baz{c} = 'd';
> baz{e} = 'f';
> baz{g} = 'h';
> ....
> ...
> ..
>
> sub foo {
> my ( $bar ) = @_;
> print $baz{$bar};
> }
>
> Any suggestions?
>
> Eric
>


hi,

hereafter is a sample code that should help you ; in this case, the key
is the position (an integer), but you can also easily match the
structure with something else, a string in your case

document('') is used to load the stylesheet itself

you MUST involve a prefix when you define your own structure

<?xml version="1.0" encoding="ISO-8859-1" ?>
<xsl:stylesheet version="1.0"
xmlnssl="http://www.w3.org/1999/XSL/Transform"
xmlns:date="*** Processing dates ***">

<date:month-names>
<date:month short="jan">january</date:month>
<date:month short="feb">february</date:month>
<date:month short="mar">march</date:month>
<date:month short="apr">april</date:month>
<date:month short="may">may</date:month>
<date:month short="jun">june</date:month>
<date:month short="jul">jully</date:month>
<date:month short="aug">august</date:month>
<date:month short="sep">september</date:month>
<date:month short="oct">october</date:month>
<date:month short="nov">november</date:month>
<date:month short="dec">december</date:month>
</date:month-names>

<xsl:template name="date:month-name">
<!--returns the name of the month from its number-->
<xslaram name="month" select="0"/>
<xsl:value-of
select="document('')/*/date:month-names/date:month[$month]"/>
</xsl:template>
</xsl:stylesheet>

--
Cordialement,

///
(. .)
-----ooO--(_)--Ooo-----
| Philippe Poulard |
-----------------------
 
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Joris Gillis
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      10-08-2004
On Fri, 08 Oct 2004 11:59:44 -0400, Eric Anderson <(E-Mail Removed)> wrote:

> Got a quick question trying to figure out the XSLT way of implementing
> the functionality of associative arrays. Basically want I want to do is
> the following:
>
> <xsl:variable name="a" select="'b'"/>
> <xsl:variable name="c" select="'d'"/>
> <xsl:variable name="e" select="'f'"/>
> <xsl:variable name="g" select="'h'"/>
> ....
> ...
> ..
>
>
> <xsl:template name="foo">
> <xslaram name="bar">
> <xsl:value-of select="${$bar}"/>
> </xsl:template>



Hi,

I'd suggest you use xml nodes to store the 'array'.

The following tree could represent the array:

<xsl:variable name="array">
<i ref="a">b</i>
<i ref="c">d</i>
<i ref="e">f</i>
<i ref="g">h</i>
</xsl:variable>

The code to access it would be something like:

<xsl:template name="foo">
<xslaram name="bar">
<xsl:value-of select="$array[@ref=$bar]"/>
</xsl:template>

In stead of using node-tree variables you could also store this array in a
seperate xml file
suppose the file's name is 'array.xml', template foo would be like:

<xsl:template name="foo">
<xslaram name="bar">
<xsl:value-of select="document('array.xml')//i[@ref=$bar]"/>
</xsl:template>



regards,

--
Joris Gillis (http://www.ticalc.org/cgi-bin/acct-v...i?userid=38041)
Ceterum censeo XML omnibus esse utendum
 
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Eric Anderson
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      10-08-2004
Joris Gillis wrote:
> I'd suggest you use xml nodes to store the 'array'.


What you suggested is exactly what I was looking for. You are an immense
help. Thank you so much.

Eric

 
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Eric Anderson
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      10-08-2004
Philippe Poulard wrote:
> hereafter is a sample code that should help you


What you and Joris Gills sent is exactly what I was looking for. I knew
there had to be a good way to do what I wanted. It is funny your example
deals with calendars. That is actually what this is all related to. Once
again thanks for your help.

Eric

 
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David Carlisle
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      10-08-2004

I guess you want an XML document rather than an array.
Given
a file.xml with
<x>
<foo x="a">b</foo>
<foo x="c">d</foo>
....

then your

<xslaram name="bar">
<xsl:value-of select="${$bar}"/>


is, I believe,

select="document('file.xml')/x/foo[@x=$bar]"

David
 
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Eric Anderson
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      10-09-2004
Joris Gillis wrote:
> <xsl:template name="foo">
> <xslaram name="bar">
> <xsl:value-of select="$array[@ref=$bar]"/>
> </xsl:template>


I am trying a variation on what both you and Philippe Poulard suggested.
Basically what I am trying to do is store some calendar information as
a variable that I can use in some of my XSLT templates. I have created
the following variable:

<xsl:variable name="calendar_info">
<cal:month name="January">
<cal:abbrev>Jan</cal:abbrev>
<calrev>December</calrev>
<cal:next>Feburary</cal:next>
</cal:month>
<cal:month name="Feburary">
<cal:abbrev>Feb</cal:abbrev>
<calrev>January</calrev>
<cal:next>March</cal:next>
</cal:month>
<cal:month name="March">
<cal:abbrev>Mar</cal:abbrev>
<calrev>Feburary</calrev>
<cal:next>April</cal:next>
</cal:month>
<cal:month name="April">
<cal:abbrev>Apr</cal:abbrev>
<calrev>March</calrev>
<cal:next>May</cal:next>
</cal:month>
<cal:month name="May">
<cal:abbrev>May</cal:abbrev>
<calrev>April</calrev>
<cal:next>June</cal:next>
</cal:month>
<cal:month name="June">
<cal:abbrev>Jun</cal:abbrev>
<calrev>May</calrev>
<cal:next>July</cal:next>
</cal:month>
<cal:month name="July">
<cal:abbrev>Jul</cal:abbrev>
<calrev>June</calrev>
<cal:next>August</cal:next>
</cal:month>
<cal:month name="August">
<cal:abbrev>Aug</cal:abbrev>
<calrev>July</calrev>
<cal:next>September</cal:next>
</cal:month>
<cal:month name="September">
<cal:abbrev>Sep</cal:abbrev>
<calrev>August</calrev>
<cal:next>October</cal:next>
</cal:month>
<cal:month name="October">
<cal:abbrev>Oct</cal:abbrev>
<calrev>September</calrev>
<cal:next>November</cal:next>
</cal:month>
<cal:month name="November">
<cal:abbrev>Nov</cal:abbrev>
<calrev>October</calrev>
<cal:next>December</cal:next>
</cal:month>
<cal:month name="December">
<cal:abbrev>Dec</cal:abbrev>
<calrev>November</calrev>
<cal:next>January</cal:next>
</cal:month>
</xsl:variable>

My main goal right now is to find out the next month so that I can
iterate through a list of months. I figured while I was at it I would
put other information in the structure which might be useful for the
future. This variable is defined in a separate xsl file so that many xsl
templates can use the information. I now am trying to use the
information. So if I do

<xsl:value-of select="$calendar_info/cal:month[@name='January']/cal:abbrev/>

I get an error. I want this to return the abbreviated version of January
('Jan'). If I do

<xsl:value-of select="$calendar_info"/>

then I get all the content of the variable but how do I select the nodes
in the variable. Any help is greatly appreciated.

Thanks,

Eric

 
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Joris Gillis
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      10-09-2004
> So if I do
>
> <xsl:value-of
> select="$calendar_info/cal:month[@name='January']/cal:abbrev/>
>
> I get an error. I want this to return the abbreviated version of January
> ('Jan').


Hi,

To deal with the error:
First, look if the typo in your mail appears in your xsl.
(the select attribute should have an ending quote)
Secondly, make sure you defined the 'cal' namespace in both xsl files.
Finally, make sure you're using xsl 1.1 and a processor that supports it.
(
If your processor does not support version 1.1, you could still use:
<xsl:value-of
select="document('templates.xsl')//cal:month[@name='January']/cal:abbrev"/>
)

<xsl:value-of
select="$calendar_info/cal:month[@name='January']/cal:abbrev"/>
returns 'Jan'. Tested with saxon.


regards,

--
Joris Gillis (http://www.ticalc.org/cgi-bin/acct-v...i?userid=38041)
Ceterum censeo XML omnibus esse utendum
 
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Ben Edgington
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      10-11-2004
Eric Anderson <(E-Mail Removed)> writes:

> Philippe Poulard wrote:
> > hereafter is a sample code that should help you

>
> What you and Joris Gills sent is exactly what I was looking for. I
> knew there had to be a good way to do what I wanted. It is funny your
> example deals with calendars. That is actually what this is all
> related to. Once again thanks for your help.


Just a follow-up to the previous excellent suggestions. Experience
has shown me that combining this with the the xsl:key and key()
functionality is an order-of-magnitude faster on my applications. The
simple XPath lookup is neater but no faster than a sequence of if
statements (sequential search). I believe most, if not all, processors
use hashes to implement the key() stuff.

So if performance matters to you have a look into it.

Here's a snippet from a (non calendar-related) example where I use it.

----
<arr:books>
<arr:book n="01" name="Genesis" osisID="Gen"/>
<arr:book n="02" name="Exodus" osisID="Exod"/>
<arr:book n="03" name="Leviticus" osisID="Lev"/>
<!-- snip -->
<arr:book n="66" name="Revelation" osisID="Rev"/>
</arr:books>

<!-- Using keys is an efficient way to access the book data -->
<xsl:key name="num2osis" match="arr:book" use="@n"/>
<xsl:key name="esv2osis" match="arr:book" use="@name"/>

<!-- snip -->

<!-- Example of accessing the "array" -->
<xsl:variable name="book-name">
<xsl:for-each select="document('')"> <!-- changes the context node -->
<xsl:value-of select="key('num2osis',substring($esv-id,1,2))/@osisID"/>
</xsl:for-each>
</xsl:variable>

----

--
Ben Edgington
Mail to the address above is discarded.
Mail to ben at that address might be read.
http://www.edginet.org/
 
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Eric Anderson
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      10-11-2004
Joris Gillis wrote:
> Finally, make sure you're using xsl 1.1 and a processor that supports it.


Ah! This was the problem. I am having the xslt processor in Mozilla
process it instead of processing server-side. Evidently mozilla only
supports 1.0 since 1.1 seems to be just a working draft and seems to
have been dropped in favor of the upcoming 2.0.

> (
> If your processor does not support version 1.1, you could still use:
> <xsl:value-of
> select="document('templates.xsl')//cal:month[@name='January']/cal:abbrev"/>
> )


I ended up doing the document() method and have it working great now.
Thanks for your help.

Eric

 
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