/*******************************************************************************
 * 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.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>
	 * <p>
	 * Since 2.1, a working copy can be created on a not-yet existing
	 * compilation unit. In particular, such a working copy can then be
	 * committed in order to create the corresponding compilation unit.
	 * </p>
	 * 
	 * @param force
	 *            a flag to handle the cases when the contents of the original
	 *            resource have changed since this working copy was created
	 * @param monitor
	 *            the given progress monitor
	 * @exception JavaModelException
	 *                if this working copy could not commit. Reasons include:
	 *                <ul>
	 *                <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>.
	 * </p>
	 * <p>
	 * When it is destroyed, a REMOVED IJavaElementDelta is reported on this
	 * working copy.
	 * </p>
	 */
	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.
	 * 
	 * @param bufferFactory
	 *            the given <code>IBuffer</code> factory
	 * @return the found shared working copy for this element, <code>null</code>
	 *         if none
	 * @see IBufferFactory
	 * @since 2.0
	 */
	IJavaElement findSharedWorkingCopy(IBufferFactory bufferFactory);

	/**
	 * 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.
	 * 
	 * @return the original element the specified working copy element was
	 *         created from, or <code>null</code> if this is not a working
	 *         copy element
	 */
	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.
	 * 
	 * @return 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.
	 * 
	 * @param element
	 *            the given element
	 * @return the found elements in this compilation unit that correspond to
	 *         the given element
	 * @since 2.0
	 */
	IJavaElement[] findElements(IJavaElement element);

	/**
	 * Finds the primary type of this compilation unit (that is, the type with
	 * the same name as the compilation unit), or <code>null</code> if no such
	 * a type exists.
	 * 
	 * @return the found primary type of this 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 (that is, 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, that is 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.
	 * @return 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
	 * @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.
	 * <p>
	 * Note: if intending to share a working copy amongst several clients, then
	 * <code>#getSharedWorkingCopy</code> should be used instead.
	 * </p>
	 * <p>
	 * When the working copy instance is created, an ADDED IJavaElementDelta is
	 * reported on this working copy.
	 * </p>
	 * <p>
	 * Since 2.1, a working copy can be created on a not-yet existing
	 * compilation unit. In particular, such a working copy can then be
	 * committed in order to create the corresponding compilation unit.
	 * </p>
	 * 
	 * @exception JavaModelException
	 *                if the contents of this element can not be determined.
	 * @return 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
	 */
	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, that is 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.
	 * <p>
	 * Note: if intending to share a working copy amongst several clients, then
	 * <code>#getSharedWorkingCopy</code> should be used instead.
	 * </p>
	 * <p>
	 * When the working copy instance is created, an ADDED IJavaElementDelta is
	 * reported on this working copy.
	 * </p>
	 * <p>
	 * Since 2.1, a working copy can be created on a not-yet existing
	 * compilation unit. In particular, such a working copy can then be
	 * committed in order to create the corresponding compilation unit.
	 * </p>
	 * 
	 * @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.
	 * @return 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
	 * @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.
	 * 
	 * @return true if this working copy's original element's content has not
	 *         changed since the inception of this working copy, false otherwise
	 */
	boolean isBasedOn(IResource resource);

	/**
	 * Returns whether this element is a working copy.
	 * 
	 * @return true if this element is a working copy, false otherwise
	 */
	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>
	 * If the working copy hasn't changed, then no problem will be detected,
	 * this is equivalent to <code>IWorkingCopy#reconcile(false, null)</code>.
	 * <p>
	 * Compilation 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>
	 * @return <code>null</code>
	 */
	IMarker[] reconcile() throws JavaModelException;

	/**
	 * 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>
	 * The boolean argument allows to force problem detection even if the
	 * working copy is already consistent.
	 * <p>
	 * Compilation 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 answers nothing.
	 * <p>
	 * Note: It has been assumed that added inner types should not generate
	 * change deltas. The implementation has been modified to reflect this
	 * assumption.
	 * 
	 * @param forceProblemDetection
	 *            boolean indicating whether problem should be recomputed even
	 *            if the source hasn't changed.
	 * @param monitor
	 *            a progress monitor
	 * @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>
	 * @since 2.0
	 */
	void reconcile(boolean forceProblemDetection, IProgressMonitor monitor)
			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;
}
