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fn:replace

Replaces parts of a string that match a regular expression

Description

The fn:replace function replaces parts of a string that match a regular expression. The regular expression syntax used is defined by XML Schema with a few modifications/additions in XQueryXPath/XSLT. The $pattern argument is a regular expression. While it is nice to have the power of regular expressions, if you simply want to replace a particular sequence of characters you don't have to be familiar with regular expressions to do that; you can just specify the string you want replaced for $pattern, as long as it doesn't contain any special characters.

The $replacement argument specifies a string (not a pattern) that is to be used as a replacement.

The $flags argument allows for additional options in the interpretation of the regular expression, such as multi-line processing and case insensitivity. Flags, reluctant quantifiers and sub-expressions are features that are covered in detail in chapter 18 of the book XQuery.

For more examples of XQueryXPath/XSLT/XML Schema regular expressions, see this page.

This description is © Copyright 2007, O'Reilly Media. It is excerpted from the book XQuery by Priscilla Walmsley, O'Reilly, 2007. For a complete explanation of this function, please refer to Appendix A of the book.

Arguments and Return Type

Name	Type	Description
`$input`	`xs:string?`	the string to change
`$pattern`	`xs:string`	regular expression to match the areas to be replaced
`$replacement`	`xs:string`	the replacement string
`$flags`	`xs:string`	flags that control multiline mode, case insensitivity, etc.
return value	`xs:string`

Examples

XQuery Example	Results
`replace('query', 'r', 'as')`	`queasy`
`replace('query', 'qu', 'quack')`	`quackery`
`replace('query', '[ry]', 'l')`	`quell`
`replace('query', '[ry]+', 'l')`	`quel`
`replace('query', 'z', 'a')`	`query`
`replace('query', 'query', '')`	`zero-length string`
`replace( (), 'r', 'as')`	`zero-length string`
`replace('query', 'r?', 'as')`	Error FORX0003
`replace('query', '(r', 'as')`	Error FORX0002
`replace('Chapter', '(Chap)\|(Chapter)', 'x')`	`xter`
*The following examples show the difference between reluctant and regular quantifiers:*
`replace('reluctant', 'r.*t', 'X')`	`X`
`replace('reluctant', 'r.*?t', 'X')`	`Xant`
`replace('aaah', 'a{2,3}', 'X')`	`Xh`
`replace('aaah', 'a{2,3}?', 'X')`	`Xah`
`replace('aaaah', 'a{2,3}', 'X')`	`Xah`
`replace('aaaah', 'a{2,3}?', 'X')`	`XXh`
*The following examples exhibit the use of sub-expressions:*
`replace('Chap 2...Chap 3...Chap 4...', 'Chap (\d)', 'Sec $1.0')`	`Sec 2.0...Sec 3.0...Sec 4.0...`
`replace('abc123', '([a-z])', '$1x')`	`axbxcx123`
`replace('2315551212', '(\d{3})(\d{3})(\d{4})', '($1) $2-$3')`	`(231) 555-1212`
`replace('2006-10-18', '\d{2}(\d{2})-(\d{2})-(\d{2})', '$2/$3/$1')`	`10/18/06`
`replace('25', '(\d+)', '\$$1.00')`	`$25.00`

History

Published On	Last Updated	Contributor(s)
2006-06-27	2007-02-26	W3C, XQuery 1.0 and XPath 2.0 Functions and Operators, http://www.w3.org/TR/xpath-functions/

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