XSLT Stylesheets

1
XSLT Stylesheets

• Some more advanced examples (adapted from the
  Edinburgh LT site)

2
Overview

• Introduction to Stylesheets
• Using XSLT to create HTML
• Using XSLT to do XML to XML conversion
• Using XSLT to sort and count

3
Stylesheets

• A stylesheet is a file which contains a
  declarative set of rules for converting an XML
  document into another document, which can be XML,
  HTML, plain text

4
XSLT Transformations

• XSLT style sheet template rules
• pattern which specifies which tree it applies to
• pattern which specifies which tree it should
  output
• XSLT processor
• reads XML document and XSLT stylesheet
• carries out the instructions in the stylesheet
• outputs a new document

5
Stylesheet top-level elements

• lt!DOCTYPE xslstylesheetgt
• ltxslstylesheet xmlnsxsl"http//www.w3.org/1999/
  XSL/Transform" version"1.0"gt
• ltxsloutput method"html"/gt
• ltxsltemplate matchgt
• lt/xsltemplategt
• lt/xslstylesheetgt

6
Template Matching

• XPath is a language for addressing parts of an
  XML document, and is used by XSLT in the match
  attribute of a template e.g. lttemplate
  matchsentencegt matches any sentence element.
• The stylesheet processor goes through the XML
  document one element at a time, finds the first
  template which that element matches, and carries
  out the instructions in that template.

7
Template Matching (cont)

• If the element does not match any template in the
  stylesheet, then the default behaviour is for the
  processing to pass through to the children of
  this element without carrying ot any
  instructions.
• When the processing reaches an element which has
  only text children, the result of processing
  these children is to print out the text.

8
Some examples of patterns

• matches any element
• / matches the top-level element
• sentence/word matches any word element with a
  sentence parent
• word_at_posnoun matches any noun element whose
  pos attribute has the value noun
• Many many other possibilities

9
Using XSLT to create HTML

• Write a stylesheet which creates an HTML document
• Load the document into a browser
• (Some browsers will do the XSL processing
  internally e.g. IE5 but many others dont yet
  allow this )

10
displaysentence.xsl

• ltxsltemplate match"/"gt
• lthtmlgtltheadgtlttitlegtParagraphlt/titlegtlt/headgt
• ltbodygt
• ltxslapply-templates/gt
• lt/bodygt
• lt/htmlgt
• lt/xsltemplategt
• ltxsltemplate match"word_at_pos'noun'"gt
• ltfont color"red"gt
• ltxslapply-templates/gt
• lt/fontgt
• lt/xsltemplategt

11
removemarkup.xsl

• ltxsltemplate match"word"gt
• ltxslcopygt
• ltxslcopy-of select"_at_"/gt
• ltxslapply-templates/gt
• lt/xslcopygt
• lt/xsltemplategt

12
Treatment of whitespace

• You can specify what should happen to the
  whitespace in a document using the
  ltxslstrip-space/gt and ltxslpreserve-space/gt
  elements. Each of these takes an element
  attribute which contains a list of element names.
• If you want to see how this works, try putting
• ltxslstrip-space elementsparagraph/gt or
• ltxslstrip-space elementsparagraph sentence/gt
• below the
• ltxsloutput methodxml/gt declaration.

13
Sorting

• XSLT can be used to sort elements by alphabetical
  or numerical order, according to attribute
  values, text contents, in ascending or descending
  order, and more

14
sortwords.xsl

• ltxsltemplate match"sentence"gt
• ltxslapply-templates select"word"gt
• ltxslsort select"."/gt
• lt/xslapply-templatesgt
• lt/xsltemplategt
• ltxsltemplate match"word"gt
• ltxslcopygt
• ltxslcopy-of select"_at_"/gt
• ltxslapply-templates/gt
• lt/xslcopygt
• lt/xsltemplategt

15
Counting

• XSLT can also be used to count or number elements

16
countwords.xsl

• ltxsltemplate match"sentence"gt
• ltxslfor-each select"word"gt
• ltpgt
• ltxslnumber value"position()" format"1.
  "/gt
• ltxslvalue-of select"."/gt
• lt/pgt
• lt/xslfor-eachgt
• lt/xsltemplategt