Module org.apache.jena.core
Package org.apache.jena.graph.impl

Class GraphBase

java.lang.Object
org.apache.jena.graph.impl.GraphBase
All Implemented Interfaces:
Graph, GraphWithPerform
Direct Known Subclasses:
BaseInfGraph, CollectionGraph, CompositionBase, GraphMemBase
public abstract class GraphBase extends Object implements GraphWithPerform
GraphBase is an implementation of Graph that provides some convenient base functionality for Graph implementations.

Subtypes of GraphBase must provide performAdd(Triple), performDelete(Triple), graphBaseFind(TripleMatch,TripleAction), and graphBaseSize(). GraphBase provides default implementations of the other methods, including the other finds (on top of that one), a simple-minded prepare, and contains. GraphBase also handles the event-listening and registration interfaces.

When a GraphBase is closed, future operations on it may throw an exception.

  • Field Details

    • TOSTRING_TRIPLE_BASE

      public static final int TOSTRING_TRIPLE_BASE
      toString will not cut off up to this number of triples.
      See Also:

    • TOSTRING_TRIPLE_LIMIT

      public static final int TOSTRING_TRIPLE_LIMIT
      toString will not output more than this number of triples.
      See Also:

  • Constructor Details

    • GraphBase

      public GraphBase()
      Initialise this graph.

  • Method Details

    • close

      public void close()
      Close this graph. Subgraphs may extend to discard resources.
      Specified by:
      close in interface Graph

    • isClosed

      public boolean isClosed()
      Description copied from interface: Graph
      Answer true iff .close() has been called on this Graph.
      Specified by:
      isClosed in interface Graph

    • dependsOn

      public boolean dependsOn(Graph other)
      Default implementation answers true iff this graph is the same graph as the argument graph.
      Specified by:
      dependsOn in interface Graph
      Parameters:
      other - the graph this graph may depend on
      Returns:
      false if this does not depend on other

    • getEventManager

      public GraphEventManager getEventManager()
      Answer the event manager for this graph; allocate a new one if required. Subclasses may override if they have a more specialised event handler. The default is a SimpleEventManager.
      Specified by:
      getEventManager in interface Graph

    • notifyAdd

      public void notifyAdd(Triple t)
      Tell the event manager that the triple t has been added to the graph.

    • notifyDelete

      public void notifyDelete(Triple t)
      Tell the event manager that the triple t has been deleted from the graph.

    • getTransactionHandler

      public TransactionHandler getTransactionHandler()
      Answer a transaction handler bound to this graph. The default is SimpleTransactionHandler, which handles no transactions.
      Specified by:
      getTransactionHandler in interface Graph

    • getCapabilities

      public Capabilities getCapabilities()
      Description copied from interface: Graph
      returns this Graph's capabilities
      Specified by:
      getCapabilities in interface Graph

    • getPrefixMapping

      public PrefixMapping getPrefixMapping()
      Answer the PrefixMapping object for this graph, the same one each time.
      Specified by:
      getPrefixMapping in interface Graph

    • add

      public void add(Triple t)
      Add a triple, and notify the event manager. Subclasses should not need to override this - we might make it final. The triple is added using performAdd, and notification done by notifyAdd.
      Specified by:
      add in interface Graph
      Parameters:
      t - the triple to add to the graph

    • performAdd

      public void performAdd(Triple t)
      Add a triple to the triple store. The default implementation throws an AddDeniedException; subclasses must override if they want to be able to add triples.
      Specified by:
      performAdd in interface GraphWithPerform

    • delete

      public final void delete(Triple t)
      Delete a triple, and notify the event manager. Subclasses should not need to override this - we might make it final. The triple is added using performDelete, and notification done by notifyDelete.
      Specified by:
      delete in interface Graph
      Parameters:
      t - the triple to delete to the graph

    • performDelete

      public void performDelete(Triple t)
      Remove a triple from the triple store. The default implementation throws a DeleteDeniedException; subclasses must override if they want to be able to remove triples.
      Specified by:
      performDelete in interface GraphWithPerform

    • clear

      public void clear()
      Remove all the statements from this graph.
      Specified by:
      clear in interface Graph

    • remove

      public void remove(Node s, Node p, Node o)
      Remove all triples that match by find(s, p, o)
      Specified by:
      remove in interface Graph

    • find

      public final ExtendedIterator<Triple> find(Triple m)
      Description copied from interface: Graph
      Returns an iterator over all the Triples that match the triple pattern.
      Specified by:
      find in interface Graph
      Parameters:
      m - a Triple encoding the pattern to look for
      Returns:
      an iterator of all triples in this graph that match m

    • forTestingOnly_graphBaseFind

      public ExtendedIterator<Triple> forTestingOnly_graphBaseFind(Triple t)

    • find

      public final ExtendedIterator<Triple> find(Node s, Node p, Node o)
      Description copied from interface: Graph
      Returns an iterator over Triples matching a pattern.
      Specified by:
      find in interface Graph
      Returns:
      an iterator of triples in this graph matching the pattern.

    • contains

      public final boolean contains(Triple t)
      Answer true iff t is in the graph as revealed by find(t) being non-empty. t may contain ANY wildcards. Sub-classes may over-ride graphBaseContains for efficiency.
      Specified by:
      contains in interface Graph

    • contains

      public final boolean contains(Node s, Node p, Node o)
      Answer true if this graph contains (s, p, o); this canonical implementation cannot be over-ridden.
      Specified by:
      contains in interface Graph

    • size

      public final int size()
      Answer the size of this graph (ie the number of exposed triples). Defined as the size of the triple store plus the size of the reification store. Subclasses must override graphBaseSize() to reimplement (and reifierSize if they have some special reason for redefined that).
      Specified by:
      size in interface Graph
      See Also:

    • isEmpty

      public boolean isEmpty()
      Answer true iff this graph contains no triples.
      Specified by:
      isEmpty in interface Graph
      Implementation Note:
      The default implementation relies on contains(Triple) with Triple.ANY as the argument. Subclasses may override if necessary.

    • isIsomorphicWith

      public boolean isIsomorphicWith(Graph g)
      Answer true iff this graph is isomorphic to g according to the algorithm (indeed, method) in GraphMatcher.
      Specified by:
      isIsomorphicWith in interface Graph
      Parameters:
      g - Compare against this.
      Returns:
      boolean True if the two graphs are isomorphic.

    • toString

      public String toString()
      Answer a human-consumable representation of this graph. Not advised for big graphs, as it generates a big string: intended for debugging purposes.
      Overrides:
      toString in class Object

    • toString

      public static String toString(String prefix, Graph that)
      Answer a human-consumable representation of that. The string prefix will appear near the beginning of the string. Nodes may be prefix-compressed using that's prefix-mapping. This default implementation will display all the triples exposed by the graph (ie including reification triples if it is Standard).