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XPath 3.0 defines a new operator called the 'mapping operator'. It is denoted by the exclamation mark --!.

What does A!B mean? How do we use the ! operator? Could someone give me an example?

Mads Hansen
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Chong Lip Phang
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2 Answers2

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Simple map operator (!) works rather like /, except there is no restriction that the left hand operand must be a node-set, and there is no sorting of results into document order.

For example, (1 to 7)!(.*.) returns the sequence (1, 4, 9, 16, 25, 36, 49).

Leo Chapiro
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    Am I right in thinking that `(1 to 7)!(.*., .+.)` returns `(1, 2, 4, 4, 9, 6, 16, 8, 25, 10, 36, 12, 49, 14)`? – Davio Sep 05 '14 at 08:26
  • Hi there. Thank you for your explanation. I wonder if there is any software that can evaluate XPath 3.0? I wish to test out its various new features. – Chong Lip Phang Sep 05 '14 at 08:31
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    @Davio Yes, Davio, exactly! Chong Lip Phang: You can test XPath 3.0 online e.g. http://videlibri.sourceforge.net/cgi-bin/xidelcgi – Leo Chapiro Sep 05 '14 at 08:40
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    Most of the products that support XPath 3.0 also support XQuery 3.0, which is a superset. Examples are Saxon and BaseX. – Michael Kay Sep 05 '14 at 11:00
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Here's another example: 

let $s := "The Taming of the Shrew"
return tokenize($s, ' ')!(string-length(.)||upper-case(.))

returns ("3THE", "6TAMING", "2OF", "3THE", "5SHREW")

This also uses the new string concatenation operator "||".

Michael Kay
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