uk.ac.sheffield.jast.xml

Class Namespace

java.lang.Object

uk.ac.sheffield.jast.xml.Namespace

public class Namespace
extends java.lang.Object

Namespace is the node standing for an XML namespace. A Namespace is an adapter, wrapping an Attribute that associates a local short name with a global URI pathname, which uniquely identifies the Namespace. The URI pathname conventionally refers to a web-page defining all the Elements contained within the Namespace; however, this page is not intended to be processed. Namespaces are created by factory methods, to ensure that each distinct local name maps to a unique Namespace object. Any Markup object can discover its Namespace using the getNamespace() method.

All XML names are eventually defined within some Namespace or other. All names with the distinguishing prefix "abc" are associated with the nearest enclosing Namespace that maps the local name "xmlns:abc" to some longer URI pathname. Names with no prefix are associated with the nearest default Namespace that maps the reserved local name "xmlns" to some longer URI pathname. If no matching Namespace is found in any enclosing scope, names belong to the empty Namespace.

Version:

2.5

Author:

Anthony J H Simons

Field Summary

Fields

Modifier and Type	Field and Description
private static java.util.Map<java.lang.String,Namespace>	namespaces The collection of all Namespace objects that were created during the current Java runtime.
private Attribute	node The wrapped attribute defining this Namespace, which is an adapter offering type-safe access to the local name and full identifier.
private static java.lang.String	xmlns The name of the default Namespace, used in comparisons.

Constructor Summary

Constructors

Modifier	Constructor and Description
private	Namespace(Attribute node) Creates a Namespace by wrapping an Attribute.

Method Summary

Modifier and Type	Method and Description
static Namespace	createNamespace() Factory method for creating the empty Namespace.
static Namespace	createNamespace(Attribute node) The factory method for creating a unique Namespace from an Attribute.
static Namespace	createNamespace(java.lang.String identifier, java.lang.String pathname) The factory method for creating a unique Namespace with an identifier mapping to a pathname.
java.lang.String	getIdentifier() Returns the full local identifier of this Namespace, including any 'xmlns' prefix and short name.
java.lang.String	getName() Returns the short local name of this Namespace, used as a prefix by Elements in this Namespace.
java.lang.String	getPathname() Returns the global pathname of this Namespace, a unique identifier.
java.net.URI	getURI() Returns the URI corresponding to the global pathname, which defines this Namespace.
boolean	isDefault() Reports whether this Namespace is a default Namespace.
boolean	isEmpty() Reports whether this Namespace is the empty Namespace.

Methods inherited from class java.lang.Object

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

Field Detail

namespaces

private static java.util.Map<java.lang.String,Namespace> namespaces

The collection of all Namespace objects that were created during the current Java runtime. This is used to cache all Namespace objects as they are created, so that requests to create a Namespace with the same identifier and URI pathname always map to the same Namespace object. The keys in this map are formed by concatenating the identifier and pathname, to ensure they are always unique.

xmlns

private static java.lang.String xmlns

The name of the default Namespace, used in comparisons.

node

private Attribute node

The wrapped attribute defining this Namespace, which is an adapter offering type-safe access to the local name and full identifier.

Constructor Detail

Namespace

private Namespace(Attribute node)
           throws SemanticError

Creates a Namespace by wrapping an Attribute. This constructor is used to wrap an Attribute that associates a local identifier with a global URI pathname, and treat it as a Namespace. All factory creation methods eventually invoke this method, which validates the Attribute, to ensure that it defines a namespace.

Parameters:

node - the Attribute.

Throws:

SemanticError - if the Attribute does not define a namespace.

Method Detail

createNamespace

public static Namespace createNamespace()

Factory method for creating the empty Namespace. If the empty Namespace already exists, returns that object. Otherwise, creates a unique instance of the empty Namespace and returns it.

Returns:

the empty Namespace.

createNamespace

public static Namespace createNamespace(Attribute node)
                                 throws SemanticError

The factory method for creating a unique Namespace from an Attribute. If a Namespace already exists for this Attribute, returns the same Namespace. If not, a new Namespace is created to wrap the Attribute and treat it as a Namespace. The Attribute's identifier must be of the form: "xmlns" or "xmlns:abc" for some local name "abc" (that is used as a prefix by Elements that belong to the Namespace). The Attribute's value must be a valid URI pathname.

Parameters:

node - the Attribute.

Returns:

a unique Namespace.

Throws:

SemanticError - if the Attribute does not define a Namespace.

createNamespace

public static Namespace createNamespace(java.lang.String identifier,
                                        java.lang.String pathname)
                                 throws SemanticError

The factory method for creating a unique Namespace with an identifier mapping to a pathname. If a Namespace already exists mapping the same identifier to the same pathname, returns that Namespace. If not, a new Namespace is created. The identifier should be of the form "xmlns" or "xmlns:abc" for some local name "abc" (that is used as a namespace prefix by Elements that belong to this Namespace). The pathname must be a valid URI pathname.

Parameters:

identifier - the namespace identifier.

pathname - the URI pathname.

Returns:

a unique Namespace.

Throws:

SemanticError - if the identifier and pathname do not define a well-formed Namespace.

getName

public java.lang.String getName()

Returns the short local name of this Namespace, used as a prefix by Elements in this Namespace. If this is a default Namespace, the short local name is "xmlns".

Returns:

the short local name.

getIdentifier

public java.lang.String getIdentifier()

Returns the full local identifier of this Namespace, including any 'xmlns' prefix and short name. If this is a default Namespace, the identifier is just "xmlns".

Returns:

the local identifier of this Namespace.

getPathname

public java.lang.String getPathname()

Returns the global pathname of this Namespace, a unique identifier.

Returns:

the URI pathname.

getURI

public java.net.URI getURI()

Returns the URI corresponding to the global pathname, which defines this Namespace. Returns null if the pathname cannot be converted into a valid URI.

Returns:

the URI defining this Namespace.

isDefault

public boolean isDefault()

Reports whether this Namespace is a default Namespace. A default Namespace is one that is not associated with a short prefix name, but with the standard name "xmlns".

Returns:

true, if this Namespace's name is "xmlns".

isEmpty

public boolean isEmpty()

Reports whether this Namespace is the empty Namespace. The empty Namespace is returned whenever no other Namespace can be determined for a given Element or Attribute. The empty Namespace has an empty string for its URI pathname (as defined in the W3C standard).

Returns:

true, if this Namespace's name is the empty string.