XSLT I Robin Burke ECT 360

Outline XSLT processing XSLT syntax XPath XSLT basics Lab

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XML XSL "family" of standards XSL-FO formatting objects typesetting document = a set of geometric areas organized on pages XSLT transformations XPath supports both a language for addressing individual XML nodes

XSL-FO Example

XSLT HTML example

XSLT syntax XML document stylesheet root element templates "rule-based" processing

XSLT Processing Let L be a list of nodes Let T be a list of templates style (L, T) = Find a template t matching L Instantiate t using L May call style (L', T) Return instantiated template To process a document style ( { root }, T )

Special purpose XSLT is not a general-purpose programming language lacks many conventional facilities technically a "tree-rewriting" language XSLT 2.0 is more general purpose

Example Jeep suppliers The first one is <xsl:value-of select="/child::entries/child::entry[position() = 1]/child::address/child::name/child::text()" />

Note stylesheet element output type element

Running example value-of1

XPath XPath expression "/child::entries/child::entry[position() = 1]/child::address/child::name/child::text()" How to read "/" = root and delimiter for steps axis::step = a move in the XML document :: = "that is" or "that are" [] = apply some predicate position () = compute the position of this element in its list of siblings text() = the element content Result is a set of nodes

Axes self this node child immediate descendant descendant any descendant attribute attribute list following siblings to the right preceding siblings to the left

Steps Depends on axis element name attribute name can be associated with a predicate foo[attribute::bar='5'] entry[position() = 2]

XPath shortcuts Axes can be abbreviated default = = attribute // = descendant. = self.. = parent Steps text() can be omitted [position() = n] can be [n] Abbreviated version "/child::entries/child::entry[1]/child::address/child::name/child::text()" "/entries/entry[1]/address/name"

Example with simplified syntax

XML Document

Paths All "name" elements? All advertisers? All non-advertisers? The rating of the second entry? All advertisers with a rating above 3? The second line of every address?

For-each May want to operate on all nodes in a set for-each element instantiates contents once for every node in set

Example listing just names

Multiple templates Typically a stylesheet will have multiple templates Easier to read / debug Templates often correspond to elements More modular

Templates template element match attribute describes nodes that use the template content template to instantiate apply-templates element select attribute what nodes to use position shows where in the parent element the result is inserted

Example

Whitespace XSLT automatically removes whitespace this is often correct when it isn't use text element

Path mismatch Biggest source of errors end path has no content Check path local path template match apply-template select Match/select should overlap by one step

Example template choice

Building an element Becomes foo.org

Alternate syntax Becomes foo.org

Sorting We can sort node lists after they are selected before they are operated on for-each apply-templates Embed sort element

Sorting, cont'd What does this do?

Example complex selection and sorting

Break / Lab