org.apache.commons.geometry.euclidean.internal

Class AbstractPathConnector.ConnectableElement<E extends AbstractPathConnector.ConnectableElement<E>>

java.lang.Object

org.apache.commons.geometry.euclidean.internal.AbstractPathConnector.ConnectableElement<E>

Type Parameters:

E - Element type

All Implemented Interfaces:

Comparable<E>

Direct Known Subclasses:

AbstractLinePathConnector.ConnectableLineSubset

Enclosing class:

AbstractPathConnector<E extends AbstractPathConnector.ConnectableElement<E>>

public abstract static class AbstractPathConnector.ConnectableElement<E extends AbstractPathConnector.ConnectableElement<E>>
extends Object
implements Comparable<E>

Class used to represent connectable path elements for use with AbstractPathConnector. Subclasses must fulfill the following requirements in order for path connection operations to work correctly:

• Implement Comparable.compareTo(Object) such that elements are sorted by their start point locations. Other criteria may be used as well but elements with start points in close proximity must be grouped together.
• Implement getConnectionSearchKey() such that it returns an instance that will be placed next to elements with start points close to the current instance's end point when sorted with Comparable.compareTo(Object).
• Implement shouldContinueConnectionSearch(AbstractPathConnector.ConnectableElement, boolean) such that it returns false when the search for possible connections through a sorted list of elements may terminate.

See Also:

AbstractPathConnector

Constructor Summary

Constructors

Constructor and Description
ConnectableElement()

Method Summary

Modifier and Type	Method and Description
abstract boolean	canConnectTo(E nextElement) Return true if this instance's end point can be connected to the argument's start point.
void	connectTo(E nextElement) Connect this instance's end point to the given element's start point.
abstract boolean	endPointsEq(E other) Return true if the end point of this instance should be considered equivalent to the end point of the argument.
E	exportPath() Export the path that this element belongs to, returning the root segment.
abstract E	getConnectionSearchKey() Get a new instance used as a search key to help locate other elements with start points matching this instance's end point.
E	getNext() Get the next connected element in the path, if any.
E	getPrevious() Get the previous connected element in the path, if any.
abstract double	getRelativeAngle(E other) Return the relative angle between this element and the argument.
protected abstract E	getSelf() Return the current instance as the generic type.
abstract boolean	hasEnd() Return true if this instance has an end point that can be connected to another element's start point.
boolean	hasNext() Return true if the instance is connected to another element's start point.
boolean	hasPrevious() Return true if another element is connected to this instance's start point.
abstract boolean	hasStart() Return true if this instance has a start point that can be connected to another element's end point.
protected boolean	markExported() Set the export flag for this instance to true.
protected void	setNext(E next) Set the next connected element for this path.
protected void	setPrevious(E previous) Set the previous connected element for this path.
abstract boolean	shouldContinueConnectionSearch(E candidate, boolean ascending) Return true if the search for possible connections should continue through the sorted set of possible path elements given the current candidate element and search direction.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Comparable

compareTo

Constructor Detail

ConnectableElement

public ConnectableElement()

Method Detail

hasNext

public boolean hasNext()

Return true if the instance is connected to another element's start point.

Returns:

true if the instance has a next element

getNext

public E getNext()

Get the next connected element in the path, if any.

Returns:

the next connected segment in the path; may be null

setNext

protected void setNext(E next)

Set the next connected element for this path. This is intended for internal use only. Callers should use the connectTo(AbstractPathConnector.ConnectableElement) method instead.

Parameters:

next - next path element

hasPrevious

public boolean hasPrevious()

Return true if another element is connected to this instance's start point.

Returns:

true if the instance has a previous element

getPrevious

public E getPrevious()

Get the previous connected element in the path, if any.

Returns:

the previous connected element in the path; may be null

setPrevious

protected void setPrevious(E previous)

Set the previous connected element for this path. This is intended for internal use only. Callers should use the connectTo(AbstractPathConnector.ConnectableElement) method instead.

Parameters:

previous - previous path element

connectTo

public void connectTo(E nextElement)

Connect this instance's end point to the given element's start point. No validation is performed in this method. The canConnectTo(AbstractPathConnector.ConnectableElement) method must have been called previously.

Parameters:

nextElement - the next element in the path

exportPath

public E exportPath()

Export the path that this element belongs to, returning the root segment. This method traverses all connected element, sets their exported flags to true, and returns the root element of the path (or this element in the case of a loop). Each path can only be exported once. Later calls to this method on this instance or any of its connected elements will return null.

Returns:

the root of the path or null if the path that this element belongs to has already been exported

markExported

protected boolean markExported()

Set the export flag for this instance to true. Returns true if the flag was changed and false otherwise.

Returns:

true if the flag was changed and false if it was already set to true

hasStart

public abstract boolean hasStart()

Return true if this instance has a start point that can be connected to another element's end point.

Returns:

true if this instance has a start point that can be connected to another element's end point

hasEnd

public abstract boolean hasEnd()

Return true if this instance has an end point that can be connected to another element's start point.

Returns:

true if this instance has an end point that can be connected to another element's start point

endPointsEq

public abstract boolean endPointsEq(E other)

Return true if the end point of this instance should be considered equivalent to the end point of the argument.

Parameters:

other - element to compare end points with

Returns:

true if this instance has an end point equivalent to that of the argument

canConnectTo

public abstract boolean canConnectTo(E nextElement)

Return true if this instance's end point can be connected to the argument's start point.

Parameters:

nextElement - candidate for the next element in the path; this value is guaranteed to not be null and to contain a start point

Returns:

true if this instance's end point can be connected to the argument's start point

getRelativeAngle

public abstract double getRelativeAngle(E other)

Return the relative angle between this element and the argument.

Parameters:

other - element to compute the angle with

Returns:

the relative angle between this element and the argument

getConnectionSearchKey

public abstract E getConnectionSearchKey()

Get a new instance used as a search key to help locate other elements with start points matching this instance's end point. The only restriction on the returned instance is that it be compatible with the implementation class' Comparable.compareTo(Object) method.

Returns:

a new instance used to help locate other path elements with start points equivalent to this instance's end point

shouldContinueConnectionSearch

public abstract boolean shouldContinueConnectionSearch(E candidate,
                                                       boolean ascending)

Return true if the search for possible connections should continue through the sorted set of possible path elements given the current candidate element and search direction. The search operation stops for the given direction when this method returns false.

Parameters:

candidate - last tested candidate connection element

ascending - true if the search is proceeding in an ascending direction; false otherwise

Returns:

true if the connection search should continue

getSelf

protected abstract E getSelf()

Return the current instance as the generic type.

Returns:

the current instance as the generic type.