NAME

RDF::Core::Function - a package of functions for query language.

DESCRIPTION

When there is a function found while evaluating query, its parameters are evaluated and passed to RDF::Core::Function apropriate piece of code. The code reference is obtained in a hash returned by getFunctions() call. Each function accepts RDF::Core::Literal or RDF::Core::Resource objects as paramaters and returns an array reference to objects of the same type.

There is a special parameter - a subject parameter, which says that a function is at position of property. For example:

subproperty(schema:SomeProperty)

has no subject parameter defined and returns property names that are subproperties of given schema:SomeProperty.

data:SomeObject.subproperty(schema:SomeProperty)

has subject parameter data:SomeObject and return values of subproperties for subject.

Interface

• new(%options)

  Available options are:

  • Data

    RDF::Core::Model object that contains data to be queried.

  • Schema

    RDF::Core::Model object that contains RDF schema.

  • Factory

    RDF::Core::NodeFactory object, that produces resource and literal objects.

• getFunctions

  Returns a hash reference where each key is a name of a functions and value is a reference to an implementation code.

Functions implemented

• subclass(X)

  Not defined subject parameter:

  Find all subclasses of X in Schema and return them if they have an instance in Data.

  Defined subject parameter:

  Result is not defined, dies.

• subproperty(X)

  Not defined subject parameter:

  Find all subproperties of X in Schema and return them if they occur in Data.

  Defined subject parameter:

  Find all subproperties of X in Schema and return their values for subject, if found.

LICENSE

This package is subject to the MPL (or the GPL alternatively).

AUTHOR

Ginger Alliance, rdf@gingerall.cz

SEE ALSO

RDF::Core::Query