Expressions

Expressions are used in XSLT for a variety of purposes including:

• Selecting nodes for processing
• Specifying conditions for different ways of processing a node
• Generating text to be inserted in the result tree

Expressions occur as the value of certain attributes on XSLT-defined elements and within curly braces in attribute value templates.

Expression evaluation occurs with respect to a context. In XSLT, an outermost expression (that is, an expression that is not part of another expression) gets its context as follows:

• The context node comes from the current node.
• The context position comes from the position of the current node in the current node list; the first position is 1.
• The context size comes from the size of the current node list.
• The variable bindings are the bindings in scope on the element that has the attribute in which the expression occurs.
• The set of namespace declarations are those in scope on the element that has the attribute in which the expression occurs.
• The function library consists of those found at XPath Functions; it is an error for an expression to include a call to any other function.

See Also

Patterns