/*******************************************************************************
 * Copyright (c) 2000, 2007 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
 *
 
 *******************************************************************************/
package org.eclipse.dltk.core;

import org.eclipse.core.runtime.IPath;

/**
 * Interface of a buildpath container. A buildpath container provides a way to
 * indirectly reference a set of buildpath entries through a buildpath entry of
 * kind <code>BPE_CONTAINER</code>. Typically, a buildpath container can be used
 * to describe a complex library composed of multiple archives or projects,
 * considering also that containers can map to different set of entries on each
 * project, in other words, several projects can reference the same generic
 * container path, but have each of them actually bound to a different container
 * object.
 * <p>
 * The set of entries associated with a buildpath container may contain any of
 * the following:
 * <ul>
 * <li>library entries (<code>BPE_LIBRARY</code>)</li>
 * <li>project entries (<code>BPE_PROJECT</code>)</li>
 * </ul>
 * In particular, a buildpath container can neither reference further buildpath
 * containers or buildpath variables.
 * <p>
 * buildpath container values are persisted locally to the workspace, but are
 * not preserved from a session to another. It is thus highly recommended to
 * register a <code>buildpathContainerInitializer</code> for each referenced
 * container (through the extension point
 * "org.eclipse.dltk.core.buildpathContainerInitializer").
 * <p>
 * 
 * @see IbuildpathEntry
 * 
 */

public interface IBuildpathContainer {

	/**
	 * Kind for a container mapping to an application library
	 */
	int K_APPLICATION = 1;

	/**
	 * Kind for a container mapping to a system library
	 */
	int K_SYSTEM = 2;

	/**
	 * Kind for a container mapping to a default system library, implicitly
	 * contributed by the runtime
	 */
	int K_DEFAULT_SYSTEM = 3;

	/**
	 * Answers the set of buildpath entries this container is mapping to.
	 * <p>
	 * The set of entries associated with a buildpath container may contain any
	 * of the following:
	 * <ul>
	 * <li>library entries (<code>CPE_LIBRARY</code>)</li>
	 * <li>project entries (<code>CPE_PROJECT</code>)</li>
	 * </ul>
	 * A buildpath container can neither reference further buildpath containers
	 * or buildpath variables.
	 * </p>
	 * <p>
	 * This method is called by the script model when it needs to resolve this
	 * buildpath container entry into a list of library and project entries. The
	 * method is typically called exactly once for a given script project, and
	 * the resulting list of entries cached internally by the script model. This
	 * method must not be called by other clients.
	 * <p>
	 * There are a wide variety of conditions under which this method may be
	 * invoked. To ensure that the implementation does not interfere with
	 * correct functioning of the script model, the implementation should use
	 * only the following script model APIs:
	 * <ul>
	 * <li>
	 * {@link DLTKCore#newLibraryEntry(IPath, IPath, IPath, boolean, boolean)}
	 * and variants</li>
	 * <li>{@link DLTKCore#newProjectEntry(IPath, boolean)} and variants</li>
	 * <li>{@link DLTKCore#create(org.eclipse.core.resources.IWorkspaceRoot)}</li>
	 * <li>{@link DLTKCore#create(org.eclipse.core.resources.IProject)}</li>
	 * <li>{@link IScriptModel#getScriptProjects()}</li>
	 * <li>{@link IScriptProject#getRawbuildpath()}</li>
	 * <li>{@link IScriptProject#readRawbuildpath()}</li>
	 * <li>{@link IScriptProject#getOutputLocation()}</li>
	 * <li>{@link IScriptProject#readOutputLocation()}</li>
	 * <li>script element operations marked as "handle-only"</li>
	 * </ul>
	 * The effects of using other script model APIs are unspecified.
	 * </p>
	 * 
	 * @return IBuildpathEntry[] - the buildpath entries this container
	 *         represents
	 * @see IBuildpathEntry
	 */
	IBuildpathEntry[] getBuildpathEntries();

	/**
	 * Answers a readable description of this container
	 * 
	 * @return String - a string description of the container
	 */
	String getDescription();

	/**
	 * Answers the kind of this container. Can be either:
	 * <ul>
	 * <li><code>K_APPLICATION</code> if this container maps to an application
	 * library</li>
	 * <li><code>K_SYSTEM</code> if this container maps to a system library</li>
	 * <li><code>K_DEFAULT_SYSTEM</code> if this container maps to a default
	 * system library (library implicitly contributed by the runtime).</li>
	 * </ul>
	 * Typically, system containers should be placed first on a build path.
	 * 
	 * @return the kind of this container
	 */
	int getKind();

	/**
	 * Answers the container path identifying this container. A container path
	 * is formed by a first ID segment followed with extra segments, which can
	 * be used as additional hints for resolving to this container.
	 * <p>
	 * The container ID is also used to identify a
	 * <code>buildpathContainerInitializer</code> registered on the extension
	 * point "org.eclipse.dltk.core.buildpathContainerInitializer", which can be
	 * invoked if needing to resolve the container before it is explicitly set.
	 * <p>
	 * 
	 * @return IPath - the container path that is associated with this container
	 */
	IPath getPath();

}