Package org.apache.commons.jxpath

Class PackageFunctions

java.lang.Object
org.apache.commons.jxpath.PackageFunctions
All Implemented Interfaces:
Functions
public class PackageFunctions extends Object implements Functions
Extension functions provided by Java classes. The class prefix specified in the constructor is used when a constructor or a static method is called. Usually, a class prefix is a package name (hence the name of this class). Let's say, we declared a PackageFunction like this: 
 new PackageFunctions("java.util.", "util")
We can now use XPaths like:
"util:Date.new()"
Equivalent to new java.util.Date()
"util:Collections.singleton('foo')"
Equivalent to java.util.Collections.singleton("foo")
"util:substring('foo', 1, 2)"
Equivalent to "foo".substring(1, 2). Note that in this case, the class prefix is not used. JXPath does not check that the first parameter of the function (the method target) is in fact a member of the package described by this PackageFunctions object.

If the first argument of a method or constructor is ExpressionContext, the expression context in which the function is evaluated is passed to the method.

There is one PackageFunctions object registered by default with each JXPathContext. It does not have a namespace and uses no class prefix. The existence of this object allows us to use XPaths like: "java.util.Date.new()" and "length('foo')" without the explicit registration of any extension functions.

  • Constructor Details

    • PackageFunctions

      public PackageFunctions(String classPrefix, String namespace)
      Constructs a new PackageFunctions.
      Parameters:
      classPrefix - class prefix
      namespace - namespace String

  • Method Details

    • getFunction

      public Function getFunction(String namespace, String name, Object[] parameters)
      Returns a Function, if found, for the specified namespace, name and parameter types.
      Specified by:
      getFunction in interface Functions
      Parameters:
      namespace - - if it is not the same as specified in the construction, this method returns null
      name - - name of the method, which can one these forms:
      • methodname, if invoking a method on an object passed as the first parameter
      • Classname.new, if looking for a constructor
      • subpackage.subpackage.Classname.new, if looking for a constructor in a subpackage
      • Classname.methodname, if looking for a static method
      • subpackage.subpackage.Classname.methodname, if looking for a static method of a class in a subpackage
      parameters - Object[] of parameters
      Returns:
      a MethodFunction, a ConstructorFunction or null if no function is found

    • getUsedNamespaces

      public Set<String> getUsedNamespaces()
      Returns the namespace specified in the constructor
      Specified by:
      getUsedNamespaces in interface Functions
      Returns:
      (singleton) namespace Set