Patterns

A pattern is a type of expression that returns a set of nodes based on a set of conditions for a node. Nodes that satisfy the conditions match the pattern. The syntax for patterns is a subset of the syntax for expressions. In particular, location paths that meet certain restrictions can be used as patterns. An expression that is also a pattern always evaluates to an object of type node-set. A node matches a pattern if the node is a member of the result of evaluating the pattern as an expression with respect to some possible context; the possible contexts are those whose context node is the node being matched or one of its ancestors.

The following table lists examples of patterns.

Pattern	Matches
`Para`	any `para` element
`*`	any element
`chapter\|appendix`	any `chapter` element and any `appendix` element
`olist/item`	any `item` element with an `olist` parent
`appendix//para`	any `para` element with an `appendix` ancestor element
`/`	the root node
`text()`	any text node
`processing-instruction()`	any processing instruction
`node()`	any node other than an attribute node and the root node
`id("W11")`	the element with unique ID `W11`
`para[1]`	any `para` element that is the first `para` child element of its parent
`*[position()=1 and self::para]`	any `para` element that is the first child element of its parent
`para[last()=1]`	any `para` element that is the only `para` child element of its parent
`items/item[position()>1]`	any `item` element that has an `items` parent and that is not the first `item` child of its parent
`item[position() mod 2 = 1]`	any `item` element that is an odd-numbered `item` child of its parent
`div[@class="appendix"]//p`	any `p` element with a `div` ancestor element that has a `class` attribute with value `appendix`
`@class`	any `class` attribute (not any element that has a `class` attribute)
`@*`	any attribute

Patterns

See Also