[xquery-talk] Recursive string concatenation ?

[Michael Kay]

Assuming your XQuery implementation supports the sibling axes (don't buy one
that doesn't),

Problem 1:

test.xq:

let $in :=
document { 
  <geometry type="POLYGON">
	<part>
		<X>1</X>
		<Y>2</Y>
		<X>3</X>
		<Y>4</Y>
		<X>5</X>
		<Y>6</Y>
	</part>
	<part>
		<X>7</X>
		<Y>8</Y>
		<X>9</X>
		<Y>10</Y>
		<X>11</X>
		<Y>12</Y>
	</part>	
  </geometry> }
return
$in/geometry/
concat(@type, '((', 
       string-join(part/
         string-join(
           for $x in X 
           return concat($x, ' ', $x/following-sibling::Y[1]),
           ','),
         ')('),
       '))')

java net.sf.saxon.Query test.xq !method=text

POLYGON((1 2,3 4,5 6)(7 8,9 10,11 12))

Pure XPath 2.0, as it happens - no XQuery needed. (And no recursion)


Problem 2:

change "for $x in X" to "for $x in (X, X[1])"

output:

POLYGON((1 2,3 4,5 6,1 2)(7 8,9 10,11 12,7 8))

Michael Kay
http://www.saxonica.com/


> -----Original Message-----
> From: talk-bounces at xquery.com 
> [mailto:talk-bounces at xquery.com] On Behalf Of Pierrick Brihaye
> Sent: 22 June 2005 17:48
> To: talk at xquery.com
> Subject: [xquery-talk] Recursive string concatenation ?
> 
> Hi,
> 
> Given the following XML :
> 
> <geometry type="POLYGON">
> 	<part>
> 		<X>1</X>
> 		<Y>2</Y>
> 		<X>3</X>
> 		<Y>4</Y>
> 		<X>5</X>
> 		<Y>6</Y>
> 	</part>
> 	<part>
> 		<X>7</X>
> 		<Y>8</Y>
> 		<X>9</X>
> 		<Y>10</Y>
> 		<X>11</X>
> 		<Y>12</Y>
> 	</part>	
> </geometry>
> 
> ... I wonder how I could write an XQuery function to get this string 
> result :
> 
> POLYGON((1 2,3 4,5 6)(7 8,9 10,11 12))
> or, better :
> POLYGON((1 2,3 4,5 6,1 2)(7 8,9 10,11 12,7 8))
> 
> Any hints ?
> 
> Cheers,
> 
> p.b.
> 
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