package org.eclipse.core.runtime;

/*
 * (c) Copyright IBM Corp. 2000, 2001.
 * All Rights Reserved.
 */

/**
 * 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>
 * This interface is not intended to be implemented by clients.
 * </p>
 */
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
 */
public IConfigurationElement[] getConfigurationElements();
/** 
 * Returns the descriptor of the plug-in that declares this extension point.
 *
 * @return the plug-in that declares this extension point
 */
public IPluginDescriptor getDeclaringPluginDescriptor();
/**
 * 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>
 */
public IExtension getExtension(String extensionId) ;
/**
 * 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
 */
public IExtension[] getExtensions();
/**
 * 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
 * @see IPluginDescriptor#getResourceString 
 */
public String getLabel();
/**
 * 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
 * @see IPluginDescriptor#getInstallURL
 */
public String getSchemaReference();
/**
 * 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 defining plug-in.
 *
 * @return the simple identifier of the extension point (e.g. <code>"builders"</code>)
 */
public String getSimpleIdentifier();
/**
 * Returns the unique identifier of this extension point.
 * This identifier is unique within the plug-in registry, and
 * is composed of the identifier of the plug-in that declared
 * 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>)
 */
public String getUniqueIdentifier();
}