de.ipcon.tools.graph

Interface OnlyToDirectedGraphNodeI

All Known Subinterfaces:

DirectedGraphNodeI, EntityI

All Known Implementing Classes:

CBOEntity, EntityWrapper, InstrumentingEntity, VirtualEntity

public interface OnlyToDirectedGraphNodeI

Represents a node in a directed graph where traversal or knowledge is primarily focused on outgoing paths ("where we're going to"). This interface is suitable for scenarios where information about incoming edges ("where we're coming from") is not available or not relevant from this particular node's perspective.

Implementations of this interface define the structure of a graph by specifying the direct successors (or "children" in a tree context) of a node. This is fundamental for algorithms involving forward traversal, such as reachability analysis, pathfinding from a source, or exploring tree-like structures.

The core contract involves providing access to these successor nodes via getToNodes(), and by extension, the outgoing edges via getOutgoingEdges().

See Also:

For nodes that also provide information about incoming edges., For the representation of edges.

Method Summary

Modifier and Type	Method and Description
default java.util.Collection<GraphEdgeI>	getOutgoingEdges() Retrieves all outgoing directed edges that originate from this node.
java.util.Collection<? extends OnlyToDirectedGraphNodeI>	getToNodes() Retrieves all direct successor nodes to which outgoing edges from this node lead.

Method Detail

getToNodes

java.util.Collection<? extends OnlyToDirectedGraphNodeI> getToNodes()

Retrieves all direct successor nodes to which outgoing edges from this node lead. These are the immediate "neighbors" in the forward direction of the graph. In a tree structure, these would typically be referred to as the children of this node.

Contract:

• Implementations of this method must not return null. If a node has no outgoing edges (i.e., no successors), an empty, non-null collection must be returned.
• The returned collection may or may not be modifiable by the caller; callers should generally not assume modifiability and treat it as read-only. If an immutable view is required, consider wrapping the returned collection (e.g., using Collections.unmodifiableCollection(Collection)).
• The order of nodes in the returned collection, if any, is implementation-dependent unless specified otherwise by the implementing class. Callers should not rely on a specific order unless documented by the concrete implementation.
• The collection should not contain null elements.

Returns:

A non-null, possibly empty, Collection of OnlyToDirectedGraphNodeI instances representing all direct successor nodes. Each element in the collection is a node reachable via a single outgoing edge from this node.

getOutgoingEdges

default java.util.Collection<GraphEdgeI> getOutgoingEdges()

Retrieves all outgoing directed edges that originate from this node. Each edge connects this node (as the source/from-node) to one of its direct successor nodes (as obtained from getToNodes()).

This default implementation iterates over the nodes returned by getToNodes() and, for each valid successor node, constructs a DefaultGraphEdge where this current node instance is the source (from-node) and the successor node is the destination (to-node).

Behavior of this default implementation:

• If getToNodes() returns an empty collection, this method will also return an empty, non-null collection.
• If getToNodes() returns a collection containing null elements, this default implementation will skip such null elements when creating edges.
• If getToNodes() (contrary to its contract) were to return null, this default implementation currently returns an empty list for robustness. However, implementers of getToNodes() must adhere to its non-null return contract.

Overriding this method: Implementers of OnlyToDirectedGraphNodeI may choose to override this default method if:

• They have a more direct or efficient way to access or construct outgoing edge objects (e.g., if edges are stored explicitly).
• Their graph edges are instances of a specific subtype of GraphEdgeI (other than DefaultGraphEdge) or carry additional state or behavior.
• They need to control the specific instances or types of GraphEdgeI returned, or if DefaultGraphEdge(OnlyToDirectedGraphNodeI, OnlyToDirectedGraphNodeI) is not suitable for their edge creation logic.

Returns:

A non-null, possibly empty, Collection of GraphEdgeI instances representing all outgoing edges from this node. In this default implementation, these are typically DefaultGraphEdge instances.

See Also:

getToNodes(), GraphEdgeI, DefaultGraphEdge