xsl:sort

Used within an xsl:for-each, xsl:apply-templates, xsl:for-each-group, or xsl:perform-sort to indicate the order in which the selected elements are processed.

Content: sequence-constructor
Permitted parent elements: xsl:apply-templates ; xsl:for-each ; xsl:for-each-group ; xsl:perform-sort

Attributes

`select?`	`expression`	A string expression that calculates the sort key. Default value ".".
`lang?`	`{ language }`	Determines the algorithm used for alphabetic collating, as an ISO language code such as `en` (English) or `de` (German). The value is used to select a collating sequence associated with the Java Locale for that language. If the attribute is omitted, and in the absence of a specific collation, Saxon uses Unicode codepoint collation.
`order?`	`{ "ascending" \| "descending" }`	Determines the sort order; the default is `ascending`.
`collation?`	`{ uri }`	The name of a collating sequence. If present it must be a collation URI recognized by Saxon: see Sorting and collations.
`stable?`	`{ boolean }`	Permitted only on the first `xsl:sort` element within a sort key. Determines the ordering when two sort key values compare equal. For such elements, the value `yes` (the default) means that the order after sorting is the same as the order before sorting; while the value `no` means that the ordering is implementation-dependent.
`case-order?`	`{ "upper-first" \| "lower-first" }`	Relevant only for `data-type="text"`; it determines whether uppercase letters are sorted before their lowercase equivalents, or vice-versa.
`data-type?`	`{ "text" \| "number" \| eqname }`	Determines whether collating is based on alphabetic sequence or numeric sequence. The permitted values are either `text` or `number`. The W3C specification permits other values and states that their effect is implementation-defined; Saxon rejects all values other than `text` and `number`. The default is to sort according to the data type of the sort key, for example `select="xs:date(@date-of-birth)"` does a chronological sort.

Saxon availability

Available in XSLT 1.0 and later versions. Available in all Saxon editions. Available for all platforms.

Notes on the Saxon implementation

The SaxonJ implementation uses java.util.Arrays.sort(): see the Javadoc documentation for that method for information about the performance characteristics of the sort algorithm. The SaxonCS implementation uses System.Array.sort(): see the .NET documentation for details of the sort algorithm used.

In XSLT 4.0, composite sort keys are allowed, but this is not yet implemented in Saxon 13.

Details

When using the Unicode Collation Algorithm, only the order and data-type control attributes are relevant - all other controls are attached as query parameters to the collation URI.

Several sort keys are allowed: they are written in major-to-minor order.

Examples

Example 1

Sorting with xsl:apply-templates. This example shows a template for a <BOOKLIST> element which processes all the child <BOOK> elements in order of their child <AUTHOR> elements; books with the same author are in descending order of the DATE attribute.

<xsl:template match="BOOKLIST"> <h2> <xsl:apply-templates select="BOOK"> <xsl:sort select="AUTHOR"/> <xsl:sort select="@DATE" order="descending"/> </xsl:apply-templates> </h2> </xsl:template>

Example 2

Sorting with xsl:for-each. This example also shows a template for a <BOOKLIST> element which processes all the child <BOOK> elements in order of their child <AUTHOR> elements.

<xsl:template match="BOOKLIST"> <h2> <xsl:for-each select="BOOK"> <xsl:sort select="AUTHOR"/> <p>AUTHOR: <xsl:value-of select="AUTHOR"></p> <p>TITLE: <xsl:value-of select="TITLE"></p> <hr/> </xsl:for-each> </h2> </xsl:template>

Example 3

Sorting with xsl:for-each using Unicode Collation Algorithm. <BOOK> elements are processed in order of their child <TITLE> elements, sorted as if they were in French dictionary order (where accents are compared in a reverse direction).

<xsl:for-each select="BOOK"> <xsl:sort select="TITLE" collation="http://www.w3.org/2013/collation/UCA?lang=fr;strength=tertiary;backwards=yes"/> <p>AUTHOR: <xsl:value-of select="AUTHOR"></p> <p>TITLE: <xsl:value-of select="TITLE"></p> <hr/> </xsl:for-each>

Links to W3C specifications

XSLT 3.0 Specification

XSLT 4.0 Specification