edu.vt.marian.common
Class InfoDesc

java.lang.Object
  |
  +--edu.vt.marian.common.InfoDesc

public class InfoDesc

extends java.lang.Object

A Information Description is a description of a digital information object in context. In MARIAN representation terms, we will understand this as a node within a web of links.

Specifically, an InfoDesc is composed of a node description plus any number of link descriptions. For the purposes of Java, we are declaring both node and link descriptions to be of class Object, so that several disparate types of descriptions can be accomodated. Only certain kinds of Objects will actually do in either case, whence the if-else if-else statements in setNodeDesc() and addLinkDesc(). These statements are deliberately designed to be extensible, so that other description types can be added in future.

The function of a node description is to describe a (subset) of nodes within some class. Any class of nodes can define one or more matching functions. In addition, all node classes support match by classID, (including subclass ID) and by exact FullID. Most also support match by exact object. Any further match is to be specified by an encoded function, which the class manager will apply to its collection of instances.

At the moment, we are only allowing a link description to consist of an exact description of a single link. Future implementations may allow link variables and link operators. A single link is fully described by specifying its type and describing the nodes at source end and sink end. In the current context, we know the description of the node at one end (the "target" end): that is the node described in the node portion of this InfoDesc. The node at the other end (the "key" end) is described by a further InfoDesc. Thus each member of the linkDesc Vector is composed of three elements:

• linkClassID -- the class of the link traversed
• direction -- whether the target is source or sink
• keyDesc -- the description of the key node

See Also:

LinkDesc, ClassManager

Field Summary

static int	BAD_PARAMS
protected Debug	debug Just for debugging
protected java.util.Vector	linkDescs
protected java.lang.Object	nodeDesc
static int	OK return values for methods of this class

Constructor Summary

InfoDesc(Debug d)
Create a new null InfoDesc.

InfoDesc(java.lang.Object node, Debug d)
Create an InfoDesc from a specific nodeDesc.

InfoDesc(java.lang.Object node, java.util.Vector links, Debug d)
Create an InfoDesc from a specific nodeDesc.

Method Summary

int	addLinkDesc(java.lang.Object ld) Add another link description to the set of links.
java.util.Enumeration	enumLinkDescs() Return an enumeration through the link description set.
boolean	isValid() Either the nodeDesc or the linkDescs (or both) must be valid, although either can also be null (but not both!).
int	numLinkDescs()
int	setNodeDesc(java.lang.Object node) Set the node description part.

Methods inherited from class java.lang.Object

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

Field Detail

debug

protected Debug debug

Just for debugging

nodeDesc

protected java.lang.Object nodeDesc

linkDescs

protected java.util.Vector linkDescs

OK

public static final int OK

return values for methods of this class

BAD_PARAMS

public static final int BAD_PARAMS

Constructor Detail

InfoDesc

public InfoDesc(Debug d)

Create a new null InfoDesc.

Parameters:

d - the eternal Debug object.

InfoDesc

public InfoDesc(java.lang.Object node,
                Debug d)

Create an InfoDesc from a specific nodeDesc.

Parameters:

node - A node description: either classID, FullID, or Function.

d - the eternal Debug object.

InfoDesc

public InfoDesc(java.lang.Object node,
                java.util.Vector links,
                Debug d)

Create an InfoDesc from a specific nodeDesc.

Parameters:

node - A node description: either ClassID, FullID, or Function.

d - the eternal Debug object.

Method Detail

isValid

public boolean isValid()

Either the nodeDesc or the linkDescs (or both) must be valid, although either can also be null (but not both!).

setNodeDesc

public int setNodeDesc(java.lang.Object node)

Set the node description part.

Parameters:

node - A node description: either ClassID, FullID, or Function.

addLinkDesc

public int addLinkDesc(java.lang.Object ld)

Add another link description to the set of links.

Parameters:

link - A link description: currently, only LinkDesc allowed.

numLinkDescs

public int numLinkDescs()

enumLinkDescs

public java.util.Enumeration enumLinkDescs()

Return an enumeration through the link description set.