XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (482 page)

There is another workaround to this problem, which is add type conversions which you know are unnecessary, but which placate the type checker. So you could write the above expression instead as:

Summary

This chapter provided details of all the type-related constructs and expressions in the XPath 2.0 language.

At the beginning of the chapter we described the
cast
and
castable
operators, and constructor functions, which are used to convert an atomic value of one type to an atomic value of a different type. We provided detailed tables showing all the type conversions that are allowed by the language.

Then, moving beyond atomic types, we examined the syntax for describing sequence types. This syntax is used only in two places in XPath, the
instance
of
and
treat
as
expressions, but XQuery and XSLT users will use the same syntax much more widely, for example, whenever the types of variables or functions are declared.

Finally, we explained how these two expressions,
instance
of
and
treat
as
, actually work.

We've now finished our tour of the XPath language syntax. The next chapter returns to XSLT with an explanation of the syntax used in match patterns, which is based on XPath syntax but is not actually part of the XPath language. Then in Chapter 13 we will look at the built-in function library—this chapter provides an alphabetical listing of all the functions in this library, including all the functions provided by every conformant XPath 2.0 processor, together with some additional functions available when XPath is used within an XSLT stylesheet.

Chapter 12

XSLT Patterns

A pattern is used in XSLT to define a condition that a node must satisfy in order to be selected. The most common use of patterns is in the
match
attribute of

, where the pattern says which nodes the template rule applies to. For example,
introduces a template rule that matches every

element. This chapter defines the syntax and meaning of XSLT patterns.

Patterns (sometimes called
match patterns
) are used in just six places in an XSLT stylesheet:

• In the
  match
  attribute of
  
  , to define the nodes in a source document to which a template applies
  
• In the
  match
  attribute of
  
  , to define the nodes in a source document to which a key definition applies
  
• In the
  count
  and
  from
  attributes of
  
  , to define which nodes are counted when generating numbers
  
• In the
  group-starting-with
  and
  group-ending-with
  attributes of
  
  , to identify a node that acts as the initial or final node in a group of related nodes
  

Patterns and Expressions

Most of the patterns found in stylesheets are simple and intuitive. For example: