com.bigdata.rdf.sparql.ast

Enum DescribeModeEnum

java.lang.Object

java.lang.Enum<DescribeModeEnum>

com.bigdata.rdf.sparql.ast.DescribeModeEnum

All Implemented Interfaces:

Serializable, Comparable<DescribeModeEnum>

public enum DescribeModeEnum
extends Enum<DescribeModeEnum>

Type-safe enumeration of the different ways in which we can evaluate a DESCRIBE query.

Author:

Bryan Thompson

See Also:

Concise Bounded Description TODO This enumeration does not allow for inverse functional constraints. That extension can help with foaf data.

Enum Constant Summary

Enum Constants

Enum Constant and Description
CBD Concise Bounded Description.
ForwardOneStep The DESCRIBE is only the attributes and forward links.
SCBD Symmetric Concise Bounded Description (SCBD).
SymmetricOneStep The DESCRIBE is the symmetric one-step neighborhood of the resource (attributes, forward links, and backward links).

Method Summary

Methods

Modifier and Type	Method and Description
boolean	isForward() Return true if the description includes the non-link attributes and forward links.
boolean	isRecursive() Return true if the description includes a recursive expansion.
boolean	isReifiedStatements() Return true if the description includes the description of reified statements found in the description.
boolean	isReverse() Return true if the description includes the reverse links.
static DescribeModeEnum	valueOf(String name) Returns the enum constant of this type with the specified name.
static DescribeModeEnum[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

ForwardOneStep

public static final DescribeModeEnum ForwardOneStep

The DESCRIBE is only the attributes and forward links.

SymmetricOneStep

public static final DescribeModeEnum SymmetricOneStep

The DESCRIBE is the symmetric one-step neighborhood of the resource (attributes, forward links, and backward links).

CBD

public static final DescribeModeEnum CBD

Concise Bounded Description.

     Given a particular node (the starting node) in a particular RDF
     graph (the source graph), a subgraph of that particular graph,
     taken to comprise a concise bounded description of the resource
     denoted by the starting node, can be identified as follows:
 
         1. Include in the subgraph all statements in the source graph
            where the subject of the statement is the starting node;
         
         2. Recursively, for all statements identified in the subgraph
            thus far having a blank node object, include in the subgraph
            all statements in the source graph where the subject of the
            statement is the blank node in question and which are not
            already included in the subgraph.
         
         3. Recursively, for all statements included in the subgraph
            thus far, for all reifications of each statement in the
            source graph, include the concise bounded description
            beginning from the rdf:Statement node of each reification.
 
     This results in a subgraph where the object nodes are either URI
     references, literals, or blank nodes not serving as the subject
     of any statement [not] in the [sub]graph.
 

The text is square brackets is my own (presumed) correction to the definition of Concise Bounded Description and reflects the actual behavior of this mode.

See Also:

CBD - Concise Bounded Description

SCBD

public static final DescribeModeEnum SCBD

Symmetric Concise Bounded Description (SCBD).

 Specifically, given a particular node (the starting node) in a particular
 RDF graph (the source graph), a subgraph of that particular graph, taken
 to comprise a symmetric concise bounded description of the resource
 denoted by the starting node, can be identified as follows:
 
 1. Include in the subgraph all statements in the source graph where the
 object of the statement is the starting node;
 
 2. Recursively, for all statements identified in the subgraph thus far
 having a blank node subject not equal to the starting node, include in
 the subgraph all statements in the source graph where the object of the
 statement is the blank node in question and which are not already
 included in the subgraph.
 
 3. Recursively, for all statements included in the subgraph thus far, for
 all reifications of each statement in the source graph, include the
 symmetric concise bounded description beginning from the rdf:Statement
 node of each reification.
 
 4. Include in the subgraph the concise bounded description beginning from
 the starting node.
 
 This produces a subgraph that includes a concise bounded description,
 given the same starting point, but in addition, includes all inbound arc
 paths, up to but not beyond a URIref subject node.
 

Note: Our evaluation actually proceeds in both the forward and reverse direction at the same time. However, this is an efficiency matter and has no effect on the semantics of the description.

Method Detail

values

public static DescribeModeEnum[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (DescribeModeEnum c : DescribeModeEnum.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static DescribeModeEnum valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null

isForward

public boolean isForward()

Return true if the description includes the non-link attributes and forward links.

isReverse

public boolean isReverse()

Return true if the description includes the reverse links.

isReifiedStatements

public boolean isReifiedStatements()

Return true if the description includes the description of reified statements found in the description.

isRecursive

public boolean isRecursive()

Return true if the description includes a recursive expansion.