/*******************************************************************************
 * Copyright (c) 2000, 2003 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package net.sourceforge.phpdt.core;

import org.eclipse.core.resources.IResourceDelta;

/**
 * A Java element delta describes changes in Java element between two discrete
 * points in time. Given a delta, clients can access the element that has
 * changed, and any children that have changed.
 * <p>
 * Deltas have a different status depending on the kind of change they
 * represent. The list below summarizes each status (as returned by
 * <code>getKind</code>) and its meaning (see individual constants for a more
 * detailled description):
 * <ul>
 * <li><code>ADDED</code> - The element described by the delta has been
 * added.</li>
 * <li><code>REMOVED</code> - The element described by the delta has been
 * removed.</li>
 * <li><code>CHANGED</code> - The element described by the delta has been
 * changed in some way. Specification of the type of change is provided by
 * <code>getFlags</code> which returns the following values:
 * <ul>
 * <li><code>F_ADDED_TO_CLASSPATH</code> - A classpath entry corresponding to
 * the element has been added to the project's classpath. This flag is only
 * valid if the element is an <code>IPackageFragmentRoot</code>.</li>
 * <li><code>F_ARCHIVE_CONTENT_CHANGED</code> - The contents of an archive
 * has changed in some way. This flag is only valid if the element is an
 * <code>IPackageFragmentRoot</code> which is an archive.</li>
 * <li><code>F_CHILDREN</code> - A child of the element has changed in some
 * way. This flag is only valid if the element is an <code>IParent</code>.</li>
 * <li><code>F_CLASSPATH_REORDER</code> - A classpath entry corresponding to
 * the element has changed position in the project's classpath. This flag is
 * only valid if the element is an <code>IPackageFragmentRoot</code>.</li>
 * <li><code>F_CLOSED</code> - The underlying <code>IProject</code> has
 * been closed. This flag is only valid if the element is an
 * <code>IJavaProject</code>.</li>
 * <li><code>F_CONTENT</code> - The contents of the element have been
 * altered. This flag is only valid for elements which correspond to files.</li>
 * <li><code>F_FINE_GRAINED</code> - The delta is a fine-grained delta, that
 * is, an analysis down to the members level was done to determine if there were
 * structural changes to members of the element.</li>
 * <li><code>F_MODIFIERS</code> - The modifiers on the element have changed
 * in some way. This flag is only valid if the element is an
 * <code>IMember</code>.</li>
 * <li><code>F_OPENED</code> - The underlying <code>IProject</code> has
 * been opened. This flag is only valid if the element is an
 * <code>IJavaProject</code>.</li>
 * <li><code>F_REMOVED_FROM_CLASSPATH</code> - A classpath entry
 * corresponding to the element has been removed from the project's classpath.
 * This flag is only valid if the element is an
 * <code>IPackageFragmentRoot</code>.</li>
 * <li><code>F_SOURCEATTACHED</code> - The source attachment path or the
 * source attachment root path of a classpath entry corresponding to the element
 * was added. This flag is only valid if the element is an
 * <code>IPackageFragmentRoot</code>.</li>
 * <li><code>F_SOURCEDETACHED</code> - The source attachment path or the
 * source attachment root path of a classpath entry corresponding to the element
 * was removed. This flag is only valid if the element is an
 * <code>IPackageFragmentRoot</code>.</li>
 * <li><code>F_SUPER_TYPES</code> - One of the supertypes of an
 * <code>IType</code> has changed</li>.
 * </ul>
 * </li>
 * </ul>
 * </p>
 * <p>
 * Move operations are indicated by other change flags, layered on top of the
 * change flags described above. If element A is moved to become B, the delta
 * for the change in A will have status <code>REMOVED</code>, with change
 * flag <code>F_MOVED_TO</code>. In this case, <code>getMovedToElement</code>
 * on delta A will return the handle for B. The delta for B will have status
 * <code>ADDED</code>, with change flag <code>F_MOVED_FROM</code>, and
 * <code>getMovedFromElement</code> on delta B will return the handle for A.
 * (Note, the handle to A in this case represents an element that no longer
 * exists).
 * </p>
 * <p>
 * Note that the move change flags only describe the changes to a single
 * element, they do not imply anything about the parent or children of the
 * element.
 * </p>
 * <p>
 * The <code>F_ADDED_TO_CLASSPATH</code>,
 * <code>F_REMOVED_FROM_CLASSPATH</code> and <code>F_CLASSPATH_REORDER</code>
 * flags are triggered by changes to a project's classpath. They do not mean
 * that the underlying resource was added, removed or changed. For example, if a
 * project P already contains a folder src, then adding a classpath entry with
 * the 'P/src' path to the project's classpath will result in an
 * <code>IJavaElementDelta</code> with the <code>F_ADDED_TO_CLASSPATH</code>
 * flag for the <code>IPackageFragmentRoot</code> P/src. On the contrary, if a
 * resource is physically added, removed or changed and this resource
 * corresponds to a classpath entry of the project, then an
 * <code>IJavaElementDelta</code> with the <code>ADDED</code>,
 * <code>REMOVED</code>, or <code>CHANGED</code> kind will be fired.
 * </p>
 * <p>
 * Note that when a source attachment path or a source attachment root path is
 * changed, then the flags of the delta contain both
 * <code>F_SOURCEATTACHED</code> and <code>F_SOURCEDETTACHED</code>.
 * </p>
 * <p>
 * No assumptions should be made on whether the java element delta tree is
 * rooted at the <code>IJavaModel</code> level or not.
 * </p>
 * <p>
 * <code>IJavaElementDelta</code> object are not valid outside the dynamic
 * scope of the notification.
 * </p>
 * <p>
 * This interface is not intended to be implemented by clients.
 * </p>
 */
public interface IJavaElementDelta {

	/**
	 * Status constant indicating that the element has been added. Note that an
	 * added java element delta has no children, as they are all implicitely
	 * added.
	 */
	public int ADDED = 1;

	/**
	 * Status constant indicating that the element has been removed. Note that a
	 * removed java element delta has no children, as they are all implicitely
	 * removed.
	 */
	public int REMOVED = 2;

	/**
	 * Status constant indicating that the element has been changed, as
	 * described by the change flags.
	 * 
	 * @see #getFlags
	 */
	public int CHANGED = 4;

	/**
	 * Change flag indicating that the content of the element has changed. This
	 * flag is only valid for elements which correspond to files.
	 */
	public int F_CONTENT = 0x0001;

	/**
	 * Change flag indicating that the modifiers of the element have changed.
	 * This flag is only valid if the element is an <code>IMember</code>.
	 */
	public int F_MODIFIERS = 0x0002;

	/**
	 * Change flag indicating that there are changes to the children of the
	 * element. This flag is only valid if the element is an
	 * <code>IParent</code>.
	 */
	public int F_CHILDREN = 0x0008;

	/**
	 * Change flag indicating that the element was moved from another location.
	 * The location of the old element can be retrieved using
	 * <code>getMovedFromElement</code>.
	 */
	public int F_MOVED_FROM = 0x0010;

	/**
	 * Change flag indicating that the element was moved to another location.
	 * The location of the new element can be retrieved using
	 * <code>getMovedToElement</code>.
	 */
	public int F_MOVED_TO = 0x0020;

	/**
	 * Change flag indicating that a classpath entry corresponding to the
	 * element has been added to the project's classpath. This flag is only
	 * valid if the element is an <code>IPackageFragmentRoot</code>.
	 */
	public int F_ADDED_TO_CLASSPATH = 0x0040;

	/**
	 * Change flag indicating that a classpath entry corresponding to the
	 * element has been removed from the project's classpath. This flag is only
	 * valid if the element is an <code>IPackageFragmentRoot</code>.
	 */
	public int F_REMOVED_FROM_CLASSPATH = 0x0080;

	/**
	 * Change flag indicating that a classpath entry corresponding to the
	 * element has changed position in the project's classpath. This flag is
	 * only valid if the element is an <code>IPackageFragmentRoot</code>.
	 * 
	 * @deprecated Use F_REORDER instead.
	 */
	public int F_CLASSPATH_REORDER = 0x0100;

	/**
	 * Change flag indicating that the element has changed position relatively
	 * to its siblings. If the element is an <code>IPackageFragmentRoot</code>,
	 * a classpath entry corresponding to the element has changed position in
	 * the project's classpath.
	 * 
	 * @since 2.1
	 */
	public int F_REORDER = 0x0100;

	/**
	 * Change flag indicating that the underlying <code>IProject</code> has
	 * been opened. This flag is only valid if the element is an
	 * <code>IJavaProject</code>.
	 */
	public int F_OPENED = 0x0200;

	/**
	 * Change flag indicating that the underlying <code>IProject</code> has
	 * been closed. This flag is only valid if the element is an
	 * <code>IJavaProject</code>.
	 */
	public int F_CLOSED = 0x0400;

	/**
	 * Change flag indicating that one of the supertypes of an
	 * <code>IType</code> has changed.
	 */
	public int F_SUPER_TYPES = 0x0800;

	/**
	 * Change flag indicating that the source attachment path or the source
	 * attachment root path of a classpath entry corresponding to the element
	 * was added. This flag is only valid if the element is an
	 * <code>IPackageFragmentRoot</code>.
	 */
	public int F_SOURCEATTACHED = 0x1000;

	/**
	 * Change flag indicating that the source attachment path or the source
	 * attachment root path of a classpath entry corresponding to the element
	 * was removed. This flag is only valid if the element is an
	 * <code>IPackageFragmentRoot</code>.
	 */
	public int F_SOURCEDETACHED = 0x2000;

	/**
	 * Change flag indicating that this is a fine-grained delta, that is, an
	 * analysis down to the members level was done to determine if there were
	 * structural changes to members.
	 * <p>
	 * Clients can use this flag to find out if a compilation unit that have a
	 * <code>F_CONTENT</code> change should assume that there are no finer
	 * grained changes (<code>F_FINE_GRAINED</code> is set) or if finer
	 * grained changes were not considered (<code>F_FINE_GRAINED</code> is
	 * not set).
	 * 
	 * @since 2.0
	 */
	public int F_FINE_GRAINED = 0x4000;

	/**
	 * Change flag indicating that the element's archive content on the
	 * classpath has changed. This flag is only valid if the element is an
	 * <code>IPackageFragmentRoot</code> which is an archive.
	 * 
	 * @see IPackageFragmentRoot#isArchive
	 * @since 2.0
	 */
	public int F_ARCHIVE_CONTENT_CHANGED = 0x8000;

	/**
	 * Change flag indicating that a compilation unit has become a primary
	 * working copy, or that a primary working copy has reverted to a
	 * compilation unit. This flag is only valid if the element is an
	 * <code>ICompilationUnit</code>.
	 * 
	 * @since 3.0
	 */
	public int F_PRIMARY_WORKING_COPY = 0x10000;

	/**
	 * Change flag indicating that the raw classpath (or the output folder) of a
	 * project has changed. This flag is only valid if the element is an
	 * <code>IJavaProject</code>.
	 * 
	 * @since 3.0
	 */
	public int F_CLASSPATH_CHANGED = 0x20000;

	/**
	 * Change flag indicating that the resource of a primary compilation unit
	 * has changed. This flag is only valid if the element is a primary
	 * <code>ICompilationUnit</code>.
	 * 
	 * @since 3.0
	 */
	public int F_PRIMARY_RESOURCE = 0x40000;

	/**
	 * Returns deltas for the children that have been added.
	 * 
	 * @return deltas for the children that have been added
	 */
	public IJavaElementDelta[] getAddedChildren();

	/**
	 * Returns deltas for the affected (added, removed, or changed) children.
	 * 
	 * @return deltas for the affected (added, removed, or changed) children
	 */
	public IJavaElementDelta[] getAffectedChildren();

	/**
	 * Returns deltas for the children which have changed.
	 * 
	 * @return deltas for the children which have changed
	 */
	public IJavaElementDelta[] getChangedChildren();

	/**
	 * Returns the element that this delta describes a change to.
	 * 
	 * @return the element that this delta describes a change to
	 */
	public IJavaElement getElement();

	/**
	 * Returns flags that describe how an element has changed. Such flags should
	 * be tested using the <code>&</code> operand. For example:
	 * 
	 * <pre>
	 * if ((delta.getFlags() &amp; IJavaElementDelta.F_CONTENT) != 0) {
	 * 	// the delta indicates a content change
	 * }
	 * </pre>
	 * 
	 * @return flags that describe how an element has changed
	 */
	public int getFlags();

	/**
	 * Returns the kind of this delta - one of <code>ADDED</code>,
	 * <code>REMOVED</code>, or <code>CHANGED</code>.
	 * 
	 * @return the kind of this delta
	 */
	public int getKind();

	/**
	 * Returns an element describing this element before it was moved to its
	 * current location, or <code>null</code> if the <code>F_MOVED_FROM</code>
	 * change flag is not set.
	 * 
	 * @return an element describing this element before it was moved to its
	 *         current location, or <code>null</code> if the
	 *         <code>F_MOVED_FROM</code> change flag is not set
	 */
	public IJavaElement getMovedFromElement();

	/**
	 * Returns an element describing this element in its new location, or
	 * <code>null</code> if the <code>F_MOVED_TO</code> change flag is not
	 * set.
	 * 
	 * @return an element describing this element in its new location, or
	 *         <code>null</code> if the <code>F_MOVED_TO</code> change flag
	 *         is not set
	 */
	public IJavaElement getMovedToElement();

	/**
	 * Returns deltas for the children which have been removed.
	 * 
	 * @return deltas for the children which have been removed
	 */
	public IJavaElementDelta[] getRemovedChildren();

	/**
	 * Returns the collection of resource deltas.
	 * <p>
	 * Note that resource deltas, like Java element deltas, are generally only
	 * valid for the dynamic scope of an event notification. Clients must not
	 * hang on to these objects.
	 * </p>
	 * 
	 * @return the underlying resource deltas, or <code>null</code> if none
	 */
	public IResourceDelta[] getResourceDeltas();
}
