(require '[sigel.xpath.core :as xpath])

(def my-compiler (xpath/compiler))

(xpath/is? my-compiler "<num>1</num>" "xs:integer(num) * $two eq 2" {:two 2})

Functions for selecting and matching things in an XML file with XPath.

For examples, see the function-specific documentation for each function. The
examples assume you've required this namespace:

```
(require '[sigel.xpath.core :as xpath])
```

Every function in the `sigel.xpath.core` namespace that select or match things
in an XML document rely on an [XPathCompiler].

If you don't pass in your own `XPathCompiler` as the first argument to a
function like that, they use [`*compiler*`][dyn-compiler].

## Use variables in XPath expression or pattern

If you need to use variables in your XPath expression or pattern, you can pass
a map of variables as the last argument to your XPath operation.

The map key must implement the [QNameable] protocol. The value must implement
the [XMLValue] protocol.

If you use variables, you also need to pass in an `XPathCompiler` as the first
argument, because setting a variable mutates the `XPathCompiler` instance.

Example:

```
(def my-compiler (xpath/compiler))

(xpath/is? my-compiler "<num>1</num>" "xs:integer(num) * $two eq 2" {:two 2})
```

[XPathCompiler]: http://www.saxonica.com/html/documentation/javadoc/net/sf/saxon/s9api/XPathCompiler.html

[dyn-compiler]: sigel.xpath.core.html#var-*compiler*
[xpath-api]: sigel.xpath.core.html

[QNameable]: sigel.protocols.html#var-QNameable
[XMLValue]: sigel.protocols.html#var-XMLValue