Package org.gcube.informationsystem.dag

Class Dag<T>

  • Type Parameters:
    T - The type of the elements stored in the graph.
    public class Dag<T>
extends Object
    A single-rooted, directed, acyclic graph (DAG) -- typically a tree in practice (single inheritance), but genuinely a DAG whenever allowMultipleInheritance produces a node with more than one parent (see Node.getParents()): each node has exactly one identity, reachable through every parent that legitimately leads to it.
    Author:
    Luca Frosini (ISTI - CNR)

    • Constructor Detail

      • Dag

        public Dag()
        Constructs an empty DAG.

      • Dag

        public Dag​(NodeInformation<T> ni)
        Constructs a DAG with the given node information provider.
        Parameters:
        ni - The node information provider.

      • Dag

        public Dag​(T root,
           NodeInformation<T> ni)
        Constructs a DAG with the given root element and node information provider.
        Parameters:
        root - The root element.
        ni - The node information provider.

    • Method Detail

      • setNodeInformation

        public void setNodeInformation​(NodeInformation<T> ni)
        Sets the node information provider for this DAG, if not already set.
        Parameters:
        ni - The node information provider.

      • setRoot

        public void setRoot​(T root)
             throws RuntimeException
        Sets the root element of this DAG, if not already set.
        Parameters:
        root - The root element.
        Throws:
        RuntimeException - if the node information provider has not been set.

      • setAllowMultipleInheritance

        public void setAllowMultipleInheritance​(boolean allowMultipleInheritance)
        Sets whether multiple inheritance is allowed in this DAG.
        Parameters:
        allowMultipleInheritance - true to allow multiple inheritance.

      • getNodeInformation

        public NodeInformation<T> getNodeInformation()
        Returns the node information provider for this DAG.
        Returns:
        The node information provider.

      • addNode

        public Node<T> addNode​(T t)
        Adds a new node to the DAG.
        Parameters:
        t - The element to add.
        Returns:
        The newly created or existing node for the element.

      • getRootNode

        public Node<T> getRootNode()
        Returns the root node of the DAG.
        Returns:
        The root node.

      • elaborate

        public void elaborate​(NodeElaborator<T> nodeElaborator)
               throws Exception
        Traverses the DAG and applies the given elaborator to each node.
        Parameters:
        nodeElaborator - The elaborator to apply.
        Throws:
        Exception - if an error occurs during elaboration.

      • getNodeByIdentifier

        public Node<T> getNodeByIdentifier​(String identifier)
        Returns the node with the given identifier.
        Parameters:
        identifier - The identifier of the node.
        Returns:
        The node, or null if not found.

      • isChildOf

        public boolean isChildOf​(String referenceIdentifier,
                         String requiredChild)
        Checks if a node is a child of another node.
        Parameters:
        referenceIdentifier - The identifier of the potential parent node.
        requiredChild - The identifier of the potential child node.
        Returns:
        true if the second node is a child of the first.

      • isParentOf

        public boolean isParentOf​(String referenceIdentifier,
                          String requiredParent)
        Checks if a node is a parent of another node.
        Parameters:
        referenceIdentifier - The identifier of the potential child node.
        requiredParent - The identifier of the potential parent node.
        Returns:
        true if the second node is a parent of the first.