= Using XPath in Markup =

Markup provides basic [http://www.w3.org/TR/xpath XPath] support for matching and querying event streams.

== Limitations ==

Due to the streaming nature of the processing model, Markup uses only a subset of the [http://www.w3.org/TR/xpath XPath 1.0] language.

In particular, only the following axes are supported:
 * `attribute`
 * `child`
 * `descendant`
 * `descendant-or-self`
 * `namespace` (not completed yet)
 * `self`

This means you can't use the ancestor, parent, or sibling axes in Markup. Basically, any path expression that would require buffering of the stream is not supported.

In addition, Markup does not (yet) support numeric types in XPath: everything is treated as text or booleans. For that reason, [http://www.w3.org/TR/xpath#NT-RelationalExpr relational] or [http://www.w3.org/TR/xpath#NT-AdditiveExpr additive] operators such as `>`, `<`, or `<=` are not supported right now.

== Querying Streams ==

{{{
#!python
from markup.input import XML

doc = XML('''<doc>
 <items count="2">
      <item status="new">
        <summary>Foo</summary>
      </item>
      <item status="closed">
        <summary>Bar</summary>
      </item>
  </items>
</doc>''')
print doc.select('items/item[@status="closed"]/summary/text()')
}}}

This would result in the following output:

{{{
#!xml
Bar
}}}

== Matching in Templates ==

See MarkupTemplates#py:match

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See also: MarkupGuide, MarkupStream