Module org.jhotdraw8.graph

Package org.jhotdraw8.graph

Class AbstractDirectedGraphBuilder

java.lang.Object

org.jhotdraw8.graph.AbstractDirectedGraphBuilder

All Implemented Interfaces:

IndexedDirectedGraph

Direct Known Subclasses:

SimpleMutableDirectedGraph

public abstract class AbstractDirectedGraphBuilder
extends Object
implements IndexedDirectedGraph

AbstractDirectedGraphBuilder.

Implementation:

Example graph:

     0 ──→ 1 ──→ 2
     │     │
     ↓     ↓
     3 ←── 4
 

If the graph is inserted in the following sequence into the builder:

     buildAddVertex();
     buildAddVertex();
     buildAddVertex();
     buildAddVertex();
     buildAddVertex();
     buildAddVertex();
     build.addArrow(0, 1);
     build.addArrow(0, 3);
     build.addArrow(1, 2);
     build.addArrow(1, 4);
     build.addArrow(4, 3);
 

Then the internal representation is as follows:

• For each vertex, there is an entry in table lastArrows.
• For each arrow, there is an entry in table arrowHeads.
• arrowHeads is a linked list. The linked list is ordered from the last arrow to the first. So we have to read it backwards!
• Each entry in lastArrows contains two fields:
  1. A pointer to an entry in arrowHeads.
  2. The arrow count for this vertex.
• Each entry in arrowHeads contains two fields:
  1. A vertex.
     A tombstone=-2 marks a deleted arrow head.
  2. A pointer to the next entry in arrowHeads.
     A sentinel=-1 marks the end of a linked list.

 vertexCount: 5
 arrowCountInclusiveDeleted: 5
 deletedArrowCount: 0
 lastDeletedArrow: SENT

  vertex#    lastArrow             arrow#    arrowHeads
           pointer,count                    vertex, next
    0     [  1  ][  2  ] ─────┐       0    [  1  ][SENT ] ←┐
    1     [  2  ][  2  ] ───┐ └─────→ 1    [  3  ][  0  ] ─┘
    2     [  0  ][  0  ] X  │         2    [  2  ][SENT ] ←┐
    3     [  0  ][  0  ] X  └───────→ 3    [  4  ][  2  ] ─┘
    4     [  4  ][  1  ] ───────────→ 4    [  3  ][SENT ] X
 

If the arrow 1 → 3 is deleted, it is removed from the linked list of vertex 1. The arrow head is marked with a tombstone.

 vertexCount: 5
 arrowCountInclusiveDeleted: 5
 deletedArrowCount: 1
 lastDeletedArrow: 1

  vertex#    lastArrow             arrow#    arrowHeads
           pointer,count                    vertex, next
    0     [  1  ][  2  ] ───────────→ 0    [  1  ][SENT ]
    1     [  2  ][  2  ] ───┐         1    [TOMB ][SENT ]
    2     [  0  ][  0  ] X  │         2    [  2  ][SENT ] ←┐
    3     [  0  ][  0  ] X  └───────→ 3    [  4  ][  2 ] ─┘
    4     [  4  ][  1  ] ───────────→ 4    [  3  ][SENT ] X
 

Author:

Werner Randelshofer

Field Summary

Fields

Modifier and Type	Field	Description
protected int	arrowCountIncludingDeletedArrows	The number of used arrowHeads.
protected static final int	ARROWS_NEXT_FIELD
protected static final int	ARROWS_NUM_FIELDS
protected static final int	ARROWS_VERTEX_FIELD
protected static final int	LASTARROW_COUNT_FIELD
protected static final int	LASTARROW_NUM_FIELDS
protected static final int	LASTARROW_POINTER_FIELD
protected static final int	SENTINEL

Constructor Summary

Constructors

Constructor	Description
AbstractDirectedGraphBuilder()
AbstractDirectedGraphBuilder(int vertexCapacity, int arrowCapacity)

Method Summary

Modifier and Type	Method	Description
protected int	buildAddArrow(int a, int b)	Builder-method: adds a directed arrow from 'a' to 'b'.
protected void	buildAddVertex()	Builder-method: adds a vertex.
protected void	buildInsertVertexAt(int vidx)
protected int	buildRemoveArrowAt(int a, int i)	Removes the i-th arrow of vertex vi.
protected int	buildRemoveArrowAt(int vidx, int i, int @NonNull [] lastArrow, int @NonNull [] arrowHeads, int arrowCount)	Removes the i-th arrow of vertex v.
protected void	buildRemoveVertex(int vidx)
protected void	buildRemoveVertexAfterArrowsHaveBeenRemoved(int vidx)
void	clear()
protected int	doAddArrow(int a, int b, int @NonNull [] arrowHeads, int @NonNull [] lastArrow)	Builder-method: adds a directed arrow from 'a' to 'b'.
int	getArrowCount()	Returns the number of arrows.
protected int	getArrowIndex(int vi, int i, int @NonNull [] lastArrow, int @NonNull [] arrowHeads)
protected int	getNextArrowIndex(int vi, int i)
int	getNextAsInt(int v, int i)	Returns the i-th next vertex of v.
int	getNextCount(int v)	Returns the number of next vertices of v.
@NonNull Enumerator.OfInt	getNextVerticesOrdered(int vidx)
@NonNull Enumerator.OfInt	getNextVerticesUnordered(int vidx)
int	getVertexCount()	Returns the number of vertices V.
boolean	isOrdered()
@NonNull Enumerator.OfInt	nextVerticesEnumerator(int v)	Returns the direct successor vertices of the specified vertex.
void	setOrdered(boolean ordered)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.jhotdraw8.graph.IndexedDirectedGraph

findIndexOfNextAsInt, getNextArrowAsInt, isNextAsInt

Field Details

ARROWS_NEXT_FIELD

protected static final int ARROWS_NEXT_FIELD

See Also:

• Constant Field Values

ARROWS_NUM_FIELDS

protected static final int ARROWS_NUM_FIELDS

See Also:

• Constant Field Values

ARROWS_VERTEX_FIELD

protected static final int ARROWS_VERTEX_FIELD

See Also:

• Constant Field Values

LASTARROW_COUNT_FIELD

protected static final int LASTARROW_COUNT_FIELD

See Also:

• Constant Field Values

LASTARROW_NUM_FIELDS

protected static final int LASTARROW_NUM_FIELDS

See Also:

• Constant Field Values

LASTARROW_POINTER_FIELD

protected static final int LASTARROW_POINTER_FIELD

See Also:

• Constant Field Values

SENTINEL

protected static final int SENTINEL

See Also:

• Constant Field Values

arrowCountIncludingDeletedArrows

protected int arrowCountIncludingDeletedArrows

The number of used arrowHeads.

Constructor Details

AbstractDirectedGraphBuilder

public AbstractDirectedGraphBuilder()

AbstractDirectedGraphBuilder

public AbstractDirectedGraphBuilder(int vertexCapacity,
 int arrowCapacity)

Method Details

buildAddArrow

protected int buildAddArrow(int a,
 int b)

Builder-method: adds a directed arrow from 'a' to 'b'.

Parameters:

a - vertex a

b - vertex b

Returns:

index of the arrow

doAddArrow

protected int doAddArrow(int a,
 int b,
 int @NonNull [] arrowHeads,
 int @NonNull [] lastArrow)

Builder-method: adds a directed arrow from 'a' to 'b'.

Parameters:

a - vertex a

b - vertex b

arrowHeads - the array of arrow heads

lastArrow - the array of last arrows

buildAddVertex

protected void buildAddVertex()

Builder-method: adds a vertex.

getArrowCount

public int getArrowCount()

Description copied from interface: IndexedDirectedGraph

Returns the number of arrows.

Specified by:

getArrowCount in interface IndexedDirectedGraph

Returns:

arrow count

buildRemoveArrowAt

protected int buildRemoveArrowAt(int a,
 int i)

Removes the i-th arrow of vertex vi.

Parameters:

a - a vertex

i - the i-th arrow of vertex vi

buildRemoveArrowAt

protected int buildRemoveArrowAt(int vidx,
 int i,
 int @NonNull [] lastArrow,
 int @NonNull [] arrowHeads,
 int arrowCount)

Removes the i-th arrow of vertex v.

Parameters:

vidx - the index of the vertex v

i - the i-th arrow of vertex v

lastArrow - the array of last arrows

arrowHeads - the array of arrow heads

arrowCount - the number of arrows

buildRemoveVertex

protected void buildRemoveVertex(int vidx)

buildRemoveVertexAfterArrowsHaveBeenRemoved

protected void buildRemoveVertexAfterArrowsHaveBeenRemoved(int vidx)

buildInsertVertexAt

protected void buildInsertVertexAt(int vidx)

getNextArrowIndex

protected int getNextArrowIndex(int vi,
 int i)

getArrowIndex

protected int getArrowIndex(int vi,
 int i,
 int @NonNull [] lastArrow,
 int @NonNull [] arrowHeads)

getNextAsInt

public int getNextAsInt(int v,
 int i)

Description copied from interface: IndexedDirectedGraph

Returns the i-th next vertex of v.

Specified by:

getNextAsInt in interface IndexedDirectedGraph

Parameters:

v - a vertex index

i - the index of the desired next vertex, i ∈ {0, ..., getNextCount(v) -1 }.

Returns:

the vertex index of the i-th next vertex of v.

getNextCount

public int getNextCount(int v)

Description copied from interface: IndexedDirectedGraph

Returns the number of next vertices of v.

Specified by:

getNextCount in interface IndexedDirectedGraph

Parameters:

v - a vertex

Returns:

the number of next vertices of v.

getVertexCount

public int getVertexCount()

Description copied from interface: IndexedDirectedGraph

Returns the number of vertices V.

Specified by:

getVertexCount in interface IndexedDirectedGraph

Returns:

vertex count

clear

public void clear()

isOrdered

public boolean isOrdered()

setOrdered

public void setOrdered(boolean ordered)

nextVerticesEnumerator

public @NonNull Enumerator.OfInt nextVerticesEnumerator(int v)

Description copied from interface: IndexedDirectedGraph

Returns the direct successor vertices of the specified vertex.

Specified by:

nextVerticesEnumerator in interface IndexedDirectedGraph

Parameters:

v - a vertex index

Returns:

a collection view on the direct successor vertices of vertex

getNextVerticesUnordered

public @NonNull Enumerator.OfInt getNextVerticesUnordered(int vidx)

getNextVerticesOrdered

public @NonNull Enumerator.OfInt getNextVerticesOrdered(int vidx)