Chapter 4 - XSL Style Sheets

Summary

XSL

XSL: transformation language and formatting language:
Transformation language processes the XML source tree and creates a result tree.
Formatting language processes the result tree and creates formatted output.
XSL style sheet declared in the XML document with <?xml-stylesheet ...?>.

XSL Style Sheets

<xsl:stylesheet...> defines the XSL namespace and version.
<xsl:output...> defines the type of output for the result tree.
Templates (<xsl:template...>) match nodes in the source tree and produce a result tree.
<xsl:apply-templates...> tells the processor to process the specified templates.
Elements not in the XSL namespace are written to the result tree.

Tranformation Instructions:

Instructions to transform the source tree into the result tree.

xsl:apply-templates Process the templates for the data matching the pattern
xsl:for-each Apply a template to each occurrence of the pattern
xsl:if If-then processing
xsl:choose "Switch" statement; used with xsl:when and xsl:otherwiser
xsl:value-of Evaluates a pattern in the select attribute and outputs the resulting value as parsed text.
xsl:text Outputs the raw text within the element, including white space.
xsl:sort Used to sort elements.

String expressions (enclosed in { }) can be used within attributes when creating nodes in the result tree.

Pattern Matching:

Used to match nodes in the source tree.
<xsl:apply-templates select="name"> matches the name element within the current element in the source tree.

XSL patterns:

/ matches child nodes (e.g. author/lastname)
// Descendant nodes
| used to specify multiple nodes (e.g. chapter|appendix)
. Current node
.. Parent of the current node
* Wildcard (e.g. chapter/* matches any element within chapter)
@ Attributes (e.g. book/@used matches the used attribute of any book element
[ ] Tests (e.g. book[@used="yes"] matches any book element with a used attribute equal to yes.

xsl:apply-templates	Process the templates for the data matching the pattern
xsl:for-each	Apply a template to each occurrence of the pattern
xsl:if	If-then processing
xsl:choose	"Switch" statement; used with `xsl:when` and `xsl:otherwiser`
xsl:value-of	Evaluates a pattern in the `select` attribute and outputs the resulting value as parsed text.
xsl:text	Outputs the raw text within the element, including white space.
xsl:sort	Used to sort elements.

/	matches child nodes (e.g. `author/lastname`)
//	Descendant nodes
\|	used to specify multiple nodes (e.g. `chapter\|appendix`)
.	Current node
..	Parent of the current node
*	Wildcard (e.g. `chapter/*` matches any element within `chapter`)
@	Attributes (e.g. `book/@used` matches the `used` attribute of any `book` element
[ ]	Tests (e.g. `book[@used="yes"]` matches any `book` element with a `used` attribute equal to `yes`.