By Karl Voelker

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

• A programming language
• A way to convert XML documents to other formats
  • Usually, to other XML formats

• "Element" has a specific meaning in XML.
• An element has a name.
• An element may have attributes.
• An element may have child nodes.
• The textual form of an element's name and attributes is a tag.

Besides elements, nodes may be:

Text:

A text node

Comments (usually ignored):

Processing instructions (rare):

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

1. Evaluate the Document Element, producing the output of the transformation

Evaluating a Node

1. Find the template which best matches the node
2. Evaluate that template on the node

Why does this work?

See the browser generate this!

• Everything in a template is evaluated, and turns into part of the template's result.
• xsl: elements turn into something special
• Anything else (like unknown elements or text) turns into itself

• xsl:apply-templates evaluates to a concatenation of the results from all the templates that it runs
• What templates does it run?
  • By default, it finds a template match for each child node of the current node
  • Otherwise, you can specify which nodes for which to find template matches with the select attribute

• xsl:value-of has a select attribute
• The value of that attribute is what xsl:value-of becomes

Examples:

• The expressions in match and select attributes are XPath expressions
• XPath is a way to identify XML nodes
• Basic XPath is similar to UNIX file paths
• But, XPath can also do more

Examples:

• .
• ../foo/bar
• preceding-sibling::*
• ancestor::*[@x]

• The contents of an xsl:if are only included if the test attribute is a "true" XPath expression
• For XPath, a node reference is true if the node exists

Example:

xsl:choose is like if/else if/else statements in many languages

Example:

• Nodes are selected by the select attribute
• Contents of the xsl:for-each are evaluated once for every node selected

xsl:sort changes the order used by xsl:for-each

Example:

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

• A template may have a name attribute
• A named template may be called directly with xsl:call-template
• Called templates may take arguments
• This allows implementing many clever algorithms!

• xsl:copy copies the current node
• This template copies everything:

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

• We want to ignore most of the HTML - but leave it the same
• We want to mark all as "even" or "odd"

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

• We want to find all the primes in a range.
• We are going to use recursion!

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

1. Introduction to XSLT and XML
2. Basic XSLT Syntax
3. Clever Algorithms
   1. Row Shading
   2. Finding Primes
   3. Fibonacci Generation
4. Practical XSLT

To note that an XML document should be transformed by a particular stylesheet:

1. Fetch an XML document from a URL.
2. Use it as input!

This is a powerful technique.

You can include templates from one stylesheet into another.

• Like xsl:include, but imported templates have lower priority
• Imported templates will only be used if nothing else matches!

Questions?