Package org.apache.jena.reasoner.rulesys.impl

Class BindingStack

  • All Implemented Interfaces:
    BindingEnvironment
    public class BindingStack
extends java.lang.Object
implements BindingEnvironment
    Provides a trail of possible variable bindings for a forward rule.

    • Constructor Summary

      Constructors 
      Constructor Description
      BindingStack()
      Constructor.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      boolean bind​(int i, Node value)
      Bind the ith variable in the current envionment to the given value.
      boolean bind​(Node var, Node value)
      Bind a variable in the current envionment to the given value.
      void bindNoCheck​(Node_RuleVariable var, Node value)
      Bind a variable in the current envionment to the given value.
      void commit()
      Forget the previously pushed state but keep the current environment.
      Node getBinding​(Node node)
      If the node is a variable then return the current binding (null if not bound) otherwise return the node itself.
      Node[] getEnvironment()
      Return the current array of bindings
      Node getGroundVersion​(Node node)
      Return the most ground version of the node.
      Triple instantiate​(TriplePattern pattern)
      Instantiate a triple pattern against the current environment.
      void push()
      Save the current environment on an internal stack
      void reset​(int newSize)
      Reset the binding environment to empty.
      void unwind()
      Forget the current environment and return the previously pushed state.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • BindingStack

        public BindingStack()
        Constructor. The stack isn't ready for use until reset has been called.

    • Method Detail

      • push

        public void push()
        Save the current environment on an internal stack

      • unwind

        public void unwind()
            throws java.lang.IndexOutOfBoundsException
        Forget the current environment and return the previously pushed state.
        Throws:
        java.lang.IndexOutOfBoundsException - if there was not previous push

      • commit

        public void commit()
            throws java.lang.IndexOutOfBoundsException
        Forget the previously pushed state but keep the current environment.
        Throws:
        java.lang.IndexOutOfBoundsException - if there was not previous push

      • reset

        public void reset​(int newSize)
        Reset the binding environment to empty.
        Parameters:
        newSize - the number of variables needed for processing the new rule

      • getEnvironment

        public Node[] getEnvironment()
        Return the current array of bindings

      • getBinding

        public Node getBinding​(Node node)
        If the node is a variable then return the current binding (null if not bound) otherwise return the node itself.

      • getGroundVersion

        public Node getGroundVersion​(Node node)
        Return the most ground version of the node. If the node is not a variable just return it, if it is a variable bound in this environment return the binding, if it is an unbound variable return the variable.
        Specified by:
        getGroundVersion in interface BindingEnvironment

      • bind

        public boolean bind​(int i,
                    Node value)
        Bind the ith variable in the current envionment to the given value. Checks that the new binding is compatible with any current binding.
        Returns:
        false if the binding fails

      • bind

        public boolean bind​(Node var,
                    Node value)
        Bind a variable in the current envionment to the given value. Checks that the new binding is compatible with any current binding.
        Specified by:
        bind in interface BindingEnvironment
        Parameters:
        var - a Node_RuleVariable defining the variable to bind
        value - the value to bind
        Returns:
        false if the binding fails

      • bindNoCheck

        public void bindNoCheck​(Node_RuleVariable var,
                        Node value)
        Bind a variable in the current envionment to the given value. Overrides and ignores any current binding.
        Parameters:
        var - a Node_RuleVariable defining the variable to bind
        value - the value to bind

      • instantiate

        public Triple instantiate​(TriplePattern pattern)
        Instantiate a triple pattern against the current environment. This version handles unbound variables by turning them into bNodes.
        Specified by:
        instantiate in interface BindingEnvironment
        Parameters:
        pattern - the triple pattern to match
        Returns:
        a new, instantiated triple