model/org/eclipse/jdt/core/IWorkingCopy.java

/**********************************************************************
Copyright (c) 2000, 2001, 2002 IBM Corp. and others.
All rights reserved.   This program and the accompanying materials
are made available under the terms of the Common Public License v0.5
which accompanies this distribution, and is available at
http://www.eclipse.org/legal/cpl-v05.html
 
Contributors:
     IBM Corporation - initial API
     IBM Corporation, 2002/03/01- added notion of shared working copy
     IBM Corporation, 2002/26/01- added notion of IProblemRequestor
**********************************************************************/

package org.eclipse.jdt.core;

import org.eclipse.core.resources.IMarker;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.runtime.IProgressMonitor;

/**
 * Common protocol for Java elements that support working copies.
 * <p>
 * A working copy of a Java element acts just like a regular element (handle),
 * except it is not attached to an underlying resource. A working copy is not
 * visible to the rest of the Java model. Changes in a working copy's
 * buffer are not realized in a resource. To bring the Java model up-to-date with a working
 * copy's contents, an explicit commit must be performed on the working copy. 
 * Other operations performed on a working copy update the
 * contents of the working copy's buffer but do not commit the contents
 * of the working copy.
 * </p>
 * <p>
 * Note: The contents of a working copy is determined when a working
 * copy is created, based on the current content of the element the working
 * copy is created from. If a working copy is an <code>IOpenable</code> and is explicitly
 * closed, the working copy's buffer will be thrown away. However, clients should not
 * explicitly open and close working copies.
 * </p>
 * <p>
 * The client that creates a working copy is responsible for
 * destroying the working copy. The Java model will never automatically
 * destroy or close a working copy. (Note that destroying a working copy
 * does not commit it to the model, it only frees up the memory occupied by
 * the element). After a working copy is destroyed, the working copy cannot
 * be accessed again. Non-handle methods will throw a 
 * <code>JavaModelException</code> indicating the Java element does not exist.
 * </p>
 * <p>
 * A working copy cannot be created from another working copy.
 * Calling <code>getWorkingCopy</code> on a working copy returns the receiver.
 * </p>
 * <p>
 * This interface is not intended to be implemented by clients.
 * </p>
 */
public interface IWorkingCopy {
	
	/**
	 * Commits the contents of this working copy to its original element
	 * and underlying resource, bringing the Java model up-to-date with
	 * the current contents of the working copy.
	 *
	 * <p>It is possible that the contents of the original resource have changed
	 * since this working copy was created, in which case there is an update conflict.
	 * The value of the <code>force</code> parameter effects the resolution of
	 * such a conflict:<ul>
	 * <li> <code>true</code> - in this case the contents of this working copy are applied to
	 * 	the underlying resource even though this working copy was created before
	 *	a subsequent change in the resource</li>
	 * <li> <code>false</code> - in this case a <code>JavaModelException</code> is thrown</li>
	 * </ul>
	 *
	 * @exception JavaModelException if this working copy could not commit. Reasons include:
	 * <ul>
	 * <li> The original Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
	 * <li> A <code>CoreException</code> occurred while updating an underlying resource
	 * <li> This element is not a working copy (INVALID_ELEMENT_TYPES)
	 * <li> A update conflict (described above) (UPDATE_CONFLICT)
	 * </ul>
	 */
	void commit(boolean force, IProgressMonitor monitor) throws JavaModelException;
	
	/**
	 * Destroys this working copy, closing its buffer and discarding
	 * its structure. Subsequent attempts to access non-handle information
	 * for this working copy will result in <code>IJavaModelException</code>s. Has
	 * no effect if this element is not a working copy.
	 * <p>
	 * If this working copy is shared, it is destroyed only when the number of calls to
	 * <code>destroy()</code> is the same as the number of calls to <code>
	 * getSharedWorkingCopy(IProgressMonitor, IBufferFactory)</code>. 
	 * A REMOVED IJavaElementDelta is then reported on this working copy.
	 */
	void destroy();
	
	/**
	 * Finds the shared working copy for this element, given a <code>IBuffer</code> factory. 
	 * If no working copy has been created for this element associated with this
	 * buffer factory, returns <code>null</code>.
	 * <p>
	 * Users of this method must not destroy the resulting working copy. 
	 * 
	 * @see IBufferFactory
	 * @since 2.0
	 */
	IJavaElement findSharedWorkingCopy(IBufferFactory bufferFactory);

	/**
	 * Finds the shared working copy for this element, given a <code>IBuffer</code> factory. 
	 * If no working copy has been created for this element associated with this
	 * buffer factory, returns <code>null</code>.
	 * <p>
	 * Users of this method must not destroy the resulting working copy. 
	 * 
	 * @see IBufferFactory
	 * @deprecated - use the one with extra buffer factory instead
	 * @since 2.0
	 */
	IJavaElement findSharedWorkingCopy();	
	
	/**
	 * Returns the original element the specified working copy element was created from,
	 * or <code>null</code> if this is not a working copy element.  This is a handle
	 * only method, the returned element may or may not exist.
	 */
	IJavaElement getOriginal(IJavaElement workingCopyElement);
	
	/**
	 * Returns the original element this working copy was created from,
	 * or <code>null</code> if this is not a working copy.
	 */
	IJavaElement getOriginalElement();
	
	/** 
	 * Finds the elements in this compilation unit that correspond to
	 * the given element.
	 * An element A corresponds to an element B if:
	 * <ul>
	 * <li>A has the same element name as B.
	 * <li>If A is a method, A must have the same number of arguments as
	 *     B and the simple names of the argument types must be equals.
	 * <li>The parent of A corresponds to the parent of B recursively up to
	 *     their respective compilation units.
	 * <li>A exists.
	 * </ul>
	 * Returns <code>null</code> if no such java elements can be found
	 * or if the given element is not included in a compilation unit.
	 * 
	 * @since 2.0 
	 */
	IJavaElement[] findElements(IJavaElement element);
	
	/**
	 * Finds the primary type of this compilation unit (i.e.&nbsp;the type with the same name as the
	 * compilation unit), or <code>null</code> if no such a type exists.
	 * 
	 * @since 2.0
	 */
	IType findPrimaryType();
	
	/**
	 * Returns a shared working copy on this element using the given factory to create
	 * the buffer, or this element if this element is already a working copy.
	 * This API can only answer an already existing working copy if it is based on the same
	 * original compilation unit AND was using the same buffer factory (i.e. as defined by <code>Object#equals</code>).	 
	 * <p>
	 * The life time of a shared working copy is as follows:
	 * <ul>
	 * <li>The first call to <code>getSharedWorkingCopy(...)</code> creates a new working copy for this
	 *     element</li>
	 * <li>Subsequent calls increment an internal counter.</li>
	 * <li>A call to <code>destroy()</code> decrements the internal counter.</li>
	 * <li>When this counter is 0, the working copy is destroyed.
	 * </ul>
	 * So users of this method must destroy exactly once the working copy.
	 * <p>
	 * Note that the buffer factory will be used for the life time of this working copy, i.e. if the 
	 * working copy is closed then reopened, this factory will be used.
	 * The buffer will be automatically initialized with the original's compilation unit content
	 * upon creation.
	 * <p>
	 * When the shared working copy instance is created, an ADDED IJavaElementDelta is reported on this
	 * working copy.
	 *
	 * @param monitor a progress monitor used to report progress while opening this compilation unit
	 *                 or <code>null</code> if no progress should be reported 
	 * @param factory the factory that creates a buffer that is used to get the content of the working copy
	 *                 or <code>null</code> if the internal factory should be used
	 * @param problemRequestor a requestor which will get notified of problems detected during
	 * 	reconciling as they are discovered. The requestor can be set to <code>null</code> indicating
	 * 	that the client is not interested in problems.
	 * @exception JavaModelException if the contents of this element can
	 *   not be determined. Reasons include:
	 * <ul>
	 * <li> This Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
	 * </ul>
	 * @see IBufferFactory
	 * @see IProblemRequestor
	 * @since 2.0
	 */
	IJavaElement getSharedWorkingCopy(
		IProgressMonitor monitor,
		IBufferFactory factory,
		IProblemRequestor problemRequestor)
		throws JavaModelException;
		
	/**
	 * Returns a new working copy of this element if this element is not
	 * a working copy, or this element if this element is already a working copy.
	 *
	 * Note: if intending to share a working copy amongst several clients, then 
	 * <code>#getSharedWorkingCopy</code> should be used insted.
	 * 
	 * @exception JavaModelException if the contents of this element can
	 *   not be determined. Reasons include:
	 * <ul>
	 * <li> This Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
	 * </ul>
	 */
	IJavaElement getWorkingCopy() throws JavaModelException;
	
	/**
	 * Returns a new working copy of this element using the given factory to create
	 * the buffer, or this element if this element is already a working copy.
	 * Note that this factory will be used for the life time of this working copy, i.e. if the 
	 * working copy is closed then reopened, this factory will be reused.
	 * The buffer will be automatically initialized with the original's compilation unit content
	 * upon creation.
	 *
	 * Note: if intending to share a working copy amongst several clients, then 
	 * <code>#getSharedWorkingCopy</code> should be used insted.
	 *
	 * @param monitor a progress monitor used to report progress while opening this compilation unit
	 *                 or <code>null</code> if no progress should be reported 
	 * @param factory the factory that creates a buffer that is used to get the content of the working copy
	 *                 or <code>null</code> if the internal factory should be used
	 * @param problemRequestor a requestor which will get notified of problems detected during
	 * 	reconciling as they are discovered. The requestor can be set to <code>null</code> indicating
	 * 	that the client is not interested in problems.
	 * @exception JavaModelException if the contents of this element can
	 *   not be determined. Reasons include:
	 * <ul>
	 * <li> This Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
	 * </ul>
	 * @since 2.0
	 */
	IJavaElement getWorkingCopy(
		IProgressMonitor monitor,
		IBufferFactory factory,
		IProblemRequestor problemRequestor)
		throws JavaModelException;
		
	/**
	 * Returns whether this working copy's original element's content
	 * has not changed since the inception of this working copy.
	 */
	boolean isBasedOn(IResource resource);
	
	/**
	 * Returns whether this element is a working copy.
	 */
	boolean isWorkingCopy();
	
	/**
	 * Reconciles the contents of this working copy.
	 * It performs the reconciliation by locally caching the contents of 
	 * the working copy, updating the contents, then creating a delta 
	 * over the cached contents and the new contents, and finally firing
	 * this delta.
	 * <p>
	 * Syntax problems found in the new contents are notified through the
	 * <code>IProblemRequestor</code> interface which was passed at
	 * creation, and no longer as transient markers. Therefore this API will
	 * return <code>null</code>.
	 * <p>
	 * Note: It has been assumed that added inner types should
	 * not generate change deltas.  The implementation has been
	 * modified to reflect this assumption.
	 *
	 * @exception JavaModelException if the contents of the original element
	 *		cannot be accessed. Reasons include:
	 * <ul>
	 * <li> The original Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
	 * </ul>
	 */
	IMarker[] reconcile() throws JavaModelException;
	
	/**
	 * Restores the contents of this working copy to the current contents of
	 * this working copy's original element. Has no effect if this element
	 * is not a working copy.
	 *
	 * <p>Note: This is the inverse of committing the content of the
	 * working copy to the original element with <code>commit(boolean, IProgressMonitor)</code>.
	 *
	 * @exception JavaModelException if the contents of the original element
	 *		cannot be accessed.  Reasons include:
	 * <ul>
	 * <li> The original Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
	 * </ul>
	 */
	void restore() throws JavaModelException;
}