/*******************************************************************************
* Copyright (c) 2000, 2009 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.core.runtime;
/**
* An extension point declared in a plug-in.
* Except for the list of extensions plugged in to it, the information
* available for an extension point is obtained from the declaring plug-in's
* manifest (<code>plugin.xml</code>) file.
* <p>
* These registry objects are intended for relatively short-term use. Clients that
* deal with these objects must be aware that they may become invalid if the
* declaring plug-in is updated or uninstalled. If this happens, all methods except
* {@link #isValid()} will throw {@link InvalidRegistryObjectException}.
* For extension point objects, the most common case is code in a plug-in dealing
* with one of the extension points it declares. These extension point objects are
* guaranteed to be valid while the plug-in is active. Code in a plug-in that has
* declared that it is not dynamic aware (or not declared anything) can also safely
* ignore this issue, since the registry would not be modified while it is
* active. However, code in a plug-in that declares that it is dynamic aware
* must be careful if it access the extension point object of a different plug-in,
* because it's at risk if that other plug-in is removed. Similarly,
* tools that analyze or display the extension registry are vulnerable.
* Client code can pre-test for invalid objects by calling {@link #isValid()},
* which never throws this exception. However, pre-tests are usually not sufficient
* because of the possibility of the extension point object becoming invalid as a
* result of a concurrent activity. At-risk clients must treat
* <code>InvalidRegistryObjectException</code> as if it were a checked exception.
* Also, such clients should probably register a listener with the extension registry
* so that they receive notification of any changes to the registry.
* </p><p>
* This interface can be used without OSGi running.
* </p><p>
* This interface is not intended to be implemented by clients.
* </p>
* @noimplement This interface is not intended to be implemented by clients.
*/
public interface IExtensionPoint {
/**
* Returns all configuration elements from all extensions configured
* into this extension point. Returns an empty array if this extension
* point has no extensions configured, or none of the extensions
* contain configuration elements.
*
* @return the configuration elements for all extension configured
* into this extension point
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public IConfigurationElement[] getConfigurationElements() throws InvalidRegistryObjectException;
/**
* Returns the namespace for this extension point. This value can be used
* in various global facilities to discover this extension point's provider.
*
* @return the namespace for this extension point
* @throws InvalidRegistryObjectException if this extension point is no longer valid
* @see IExtensionRegistry
* @since 3.0
* @deprecated As namespace is no longer restricted to the contributor name,
* use {@link #getNamespaceIdentifier()} to obtain namespace name or {@link #getContributor()}
* to get the name of the contributor of this registry element.
* <p>
* In the past namespace was dictated by the name of the bundle. If bundle <code>org.abc</code>
* contributed registry element with Id of <code>MyId</code>, the namespace of
* the element was always set to <code>org.abc</code>, producing the qualified name of
* <code>org.abc.MyId</code>.
* </p><p>
* The namespace used to be the same as the bundle name. As a result, the {@link #getNamespace()}
* method was used both to obtain the name of the bundle and to obtain the namespace of a registry
* element.
* </p><p>
* Since 3.2, the extension registry allows elements to specify qualified name. The extension point
* of the plug-in <code>org.abc</code> could specify <code>org.zzz.MyExtPoint</code> as
* an Id. In this case, namespace name is <code>org.zzz</code>, but the contributor
* name is <code>org.abc</code>.
* </p><p>
* (The use of a simple Id is still a preferred way. Whenever possible, specify only the simple
* Id and let runtime take care of the rest.)
* </p><p>
* If your code used the {@link #getNamespace()} to obtain the name of the contributing bundle,
* use {@link #getContributor()}. The typical usage pattern here is to find a bundle name to obtain
* some information from the corresponding OSGi bundle. For example, deducing the file location
* specified as a relative path to the bundle install location would fall into this group.
* </p><p>
* If your code used the {@link #getNamespace()} to obtain the namespace of the registry element,
* use {@link #getNamespaceIdentifier()}. Typically, this is the case when code is trying to process
* registry elements belonging to some logical group. For example, processing notifications for all
* elements belonging to the <code>org.abc</code> namespace would fall into this category.
* </p>
*/
public String getNamespace() throws InvalidRegistryObjectException;
/**
* Returns the namespace name for this extension point.
*
* @return the namespace name for this extension point
* @throws InvalidRegistryObjectException if this extension point is no longer valid
* @since org.eclipse.equinox.registry 3.2
*/
public String getNamespaceIdentifier() throws InvalidRegistryObjectException;
/**
* Returns the contributor of this extension point.
*
* @return the contributor for this extension point
* @throws InvalidRegistryObjectException if this extension point is no longer valid
* @since org.eclipse.equinox.registry 3.2
*/
public IContributor getContributor() throws InvalidRegistryObjectException;
/**
* Returns the extension with the given unique identifier configured into
* this extension point, or <code>null</code> if there is no such extension.
* Since an extension might not have an identifier, some extensions
* can only be found via the <code>getExtensions</code> method.
*
* @param extensionId the unique identifier of an extension
* (e.g. <code>"com.example.acme.main"</code>).
* @return an extension, or <code>null</code>
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public IExtension getExtension(String extensionId) throws InvalidRegistryObjectException;
/**
* Returns all extensions configured into this extension point.
* Returns an empty array if this extension point has no extensions.
*
* @return the extensions configured into this extension point
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public IExtension[] getExtensions() throws InvalidRegistryObjectException;
/**
* Returns a displayable label for this extension point.
* Returns the empty string if no label for this extension point
* is specified in the plug-in manifest file.
* <p> Note that any translation specified in the plug-in manifest
* file is automatically applied.
* </p>
*
* @return a displayable string label for this extension point,
* possibly the empty string
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public String getLabel() throws InvalidRegistryObjectException;
/**
* When multi-language support is enabled, this method returns a displayable label
* for this extension point in the specified locale.
* Returns the empty string if no label for this extension point
* is specified in the plug-in manifest file.
* <p>
* The locale matching tries to find the best match between available translations and
* the requested locale, falling back to a more generic locale ("en") when the specific
* locale ("en_US") is not available.
* </p><p>
* If multi-language support is not enabled, this method is equivalent to the method
* {@link #getLabel()}.
* </p>
* @param locale the requested locale
* @return a displayable string label for this extension point,
* possibly the empty string
* @throws InvalidRegistryObjectException if this extension point is no longer valid
* @see IExtensionRegistry#isMultiLanguage()
* @since 3.5
*/
public String getLabel(String locale) throws InvalidRegistryObjectException;
/**
* Returns reference to the extension point schema. The schema
* reference is returned as a URL path relative to the plug-in
* installation URL.
* Returns the empty string if no schema for this extension point
* is specified in the plug-in manifest file.
*
* @return a relative URL path, or an empty string
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public String getSchemaReference() throws InvalidRegistryObjectException;
/**
* Returns the simple identifier of this extension point.
* This identifier is a non-empty string containing no
* period characters (<code>'.'</code>) and is guaranteed
* to be unique within the namespace.
*
* @return the simple identifier of the extension point (e.g. <code>"builders"</code>)
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public String getSimpleIdentifier() throws InvalidRegistryObjectException;
/**
* Returns the unique identifier of this extension point.
* This identifier is unique within the plug-in registry, and
* is composed of the namespace for this extension point
* and this extension point's simple identifier.
*
*
* @return the unique identifier of the extension point
* (e.g. <code>"org.eclipse.core.resources.builders"</code>)
* @throws InvalidRegistryObjectException if this extension point is no longer valid
*/
public String getUniqueIdentifier() throws InvalidRegistryObjectException;
/* (non-javadoc)
* @see Object#equals(java.lang.Object)
*/
public boolean equals(Object o);
/**
* Returns whether this extension point object is valid.
*
* @return <code>true</code> if the object is valid, and <code>false</code>
* if it is no longer valid
* @since 3.1
*/
public boolean isValid();
}