/*******************************************************************************
* Copyright (c) 2005, 2008 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
*
* Contributors: IBM Corporation - initial API and implementation
******************************************************************************/
package org.eclipse.core.resources.mapping;
import org.eclipse.core.resources.*;
import org.eclipse.core.runtime.*;
/**
* A remote mapping context provides a model element with a view of the remote
* state of local resources as they relate to a repository operation that is in
* progress. A repository provider can pass an instance of this interface to a
* model element when obtaining a set of traversals for a model element. This
* allows the model element to query the remote state of a resource in order to
* determine if there are resources that exist remotely but do not exist locally
* that should be included in the traversal.
* <p>
* This class may be subclassed by clients.
* </p>
*
* @see ResourceMapping
* @see ResourceMappingContext
* @since 3.2
*/
public abstract class RemoteResourceMappingContext extends ResourceMappingContext {
/**
* Refresh flag constant (bit mask value 1) indicating that the mapping will
* be making use of the contents of the files covered by the traversals
* being refreshed.
*/
public static final int FILE_CONTENTS_REQUIRED = 1;
/**
* Refresh flag constant (bit mask value 0) indicating that no additional
* refresh behavior is required.
*/
public static final int NONE = 0;
/**
* For three-way comparisons, returns an instance of IStorage in order to
* allow the caller to access the contents of the base resource that
* corresponds to the given local resource. The base of a resource is the
* contents of the resource before any local modifications were made. If the
* base file does not exist, or if this is a two-way comparison, <code>null</code>
* is returned. The provided local file handle need not exist locally. A exception
* is thrown if the corresponding base resource is not a file.
* <p>
* This method may be long running as a server may need to be contacted to
* obtain the contents of the file.
* </p>
*
* @param file the local file
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @return a storage that provides access to the contents of the local
* resource's corresponding remote resource. If the remote file does not
* exist, <code>null</code> is returned
* @exception CoreException if the contents could not be fetched. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.
* <li>The corresponding remote resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
*/
public abstract IStorage fetchBaseContents(IFile file, IProgressMonitor monitor) throws CoreException;
/**
* Returns the members of the base resource corresponding to the given container.
* The container and the returned members need not exist locally and may not
* include all children that exist locally. An empty list is returned if the base resource
* is empty or does not exist. An exception is thrown if the base resource is not
* capable of having members. This method returns <code>null</code> if
* the base members cannot be computed, in which case clients should call
* {@link #fetchMembers(IContainer, IProgressMonitor)} which returns the
* combined members for the base and remote.
* </p>
* <p>
* This method may be long running as a server may need to be contacted to
* obtain the members of the base resource.
* </p>
* <p>
* This default implementation always returns <code>null</code>, but subclasses
* may override.
* </p>
* @param container the local container
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @return the members of the base resource corresponding to the given container
* @exception CoreException if the members could not be fetched. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.</li>
* <li>The base resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
* @since 3.3
*/
public IResource[] fetchBaseMembers(IContainer container, IProgressMonitor monitor) throws CoreException {
//default implementation does nothing
//thwart compiler warning
return null;
}
/**
* Returns the combined members of the base and remote resources corresponding
* to the given container. The container need not exist locally and the result may
* include entries that do not exist locally and may not include all local
* children. An empty list is returned if the remote resource which
* corresponds to the container is empty or if the remote does not exist. An
* exception is thrown if the corresponding remote is not capable of having
* members.
* <p>
* This method may be long running as a server may need to be contacted to
* obtain the members of the container's corresponding remote resource.
* </p>
*
* @param container the local container
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @return returns the combined members of the base and remote resources
* corresponding to the given container.
* @exception CoreException if the members could not be fetched. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.</li>
* <li>The corresponding remote resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
*/
public abstract IResource[] fetchMembers(IContainer container, IProgressMonitor monitor) throws CoreException;
/**
* Returns an instance of IStorage in order to allow the caller to access
* the contents of the remote that corresponds to the given local resource.
* If the remote file does not exist, <code>null</code> is returned. The
* provided local file handle need not exist locally. A exception is thrown
* if the corresponding remote resource is not a file.
* <p>
* This method may be long running as a server may need to be contacted to
* obtain the contents of the file.
* </p>
*
* @param file the local file
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @return a storage that provides access to the contents of the local
* resource's corresponding remote resource. If the remote file does not
* exist, <code>null</code> is returned
* @exception CoreException if the contents could not be fetched. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.</li>
* <li>The corresponding remote resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
*/
public abstract IStorage fetchRemoteContents(IFile file, IProgressMonitor monitor) throws CoreException;
/**
* Returns the members of the remote resource corresponding to the given container.
* The container and the returned members need not exist locally and may not
* include all children that exist locally. An empty list is returned if the remote resource
* is empty or does not exist. An exception is thrown if the remote resource is not
* capable of having members. This method returns <code>null</code> if
* the remote members cannot be computed, in which case clients should call
* {@link #fetchMembers(IContainer, IProgressMonitor)} which returns the
* combined members for the base and remote.
* </p>
* <p>
* This method may be long running as a server may need to be contacted to
* obtain the members of the remote resource.
* </p>
* <p>
* This default implementation always returns <code>null</code>, but subclasses
* may override.
* </p>
* @param container the local container
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @return the members of the remote resource corresponding to the given container
* @exception CoreException if the members could not be fetched. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.</li>
* <li>The remote resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
* @since 3.3
*/
public IResource[] fetchRemoteMembers(IContainer container, IProgressMonitor monitor) throws CoreException {
//default implementation does nothing
//thwart compiler warning
return null;
}
/**
* Return the list of projects that apply to this context.
* In other words, the context is only capable of querying the
* remote state for projects that are contained in the
* returned list.
* @return the list of projects that apply to this context
*/
public abstract IProject[] getProjects();
/**
* For three-way comparisons, this method indicates whether local
* modifications have been made to the given resource. For two-way
* comparisons, calling this method has the same effect as calling
* {@link #hasRemoteChange(IResource, IProgressMonitor)}.
*
* @param resource the resource being tested
* @param monitor a progress monitor
* @return whether the resource contains local modifications
* @exception CoreException if the contents could not be compared. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.</li>
* <li>The corresponding remote resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
*/
public abstract boolean hasLocalChange(IResource resource, IProgressMonitor monitor) throws CoreException;
/**
* For two-way comparisons, return whether the contents of the corresponding
* remote differs from the content of the local file in the context of the
* current operation. By this we mean that this method will return
* <code>true</code> if the remote contents differ from the local
* contents.
* <p>
* For three-way comparisons, return whether the contents of the
* corresponding remote differ from the contents of the base. In other
* words, this method returns <code>true</code> if the corresponding
* remote has changed since the last time the local resource was updated
* with the remote contents.
* <p>
* For two-way comparisons, return <code>true</code> if the remote
* contents differ from the local contents. In this case, this method is
* equivalent to {@link #hasLocalChange(IResource, IProgressMonitor)}
* <p>
* This can be used by clients to determine if they need to fetch the remote
* contents in order to determine if the resources that constitute the model
* element are different in the remote location. If the local file exists
* and the remote file does not, or the remote file exists and the local
* does not then the contents will be said to differ (i.e. <code>true</code>
* is returned). Also, implementors will most likely use a timestamp based
* comparison to determine if the contents differ. This may lead to a
* situation where <code>true</code> is returned but the actual contents
* do not differ. Clients must be prepared handle this situation.
* </p>
*
* @param resource the local resource
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @return whether the contents of the corresponding remote differ from the
* base.
* @exception CoreException if the contents could not be compared. Reasons
* include:
* <ul>
* <li>The server could not be contacted for some reason.</li>
* <li>The corresponding remote resource is not a container (status code
* will be {@link IResourceStatus#RESOURCE_WRONG_TYPE}).</li>
* </ul>
*/
public abstract boolean hasRemoteChange(IResource resource, IProgressMonitor monitor) throws CoreException;
/**
* Return <code>true</code> if the context is associated with an operation
* that is using a three-way comparison and <code>false</code> if it is
* using a two-way comparison.
*
* @return whether the context is a three-way or two-way
*/
public abstract boolean isThreeWay();
/**
* Refresh the known remote state for any resources covered by the given
* traversals. Clients who require the latest remote state should invoke
* this method before invoking any others of the class. Mappings can use
* this method as a hint to the context provider of which resources will be
* required for the mapping to generate the proper set of traversals.
* <p>
* Note that this is really only a hint to the context provider. It is up to
* implementors to decide, based on the provided traversals, how to
* efficiently perform the refresh. In the ideal case, calls to
* {@link #hasRemoteChange(IResource, IProgressMonitor)} and
* {@link #fetchMembers} would not need to contact the server after a call to a
* refresh with appropriate traversals. Also, ideally, if
* {@link #FILE_CONTENTS_REQUIRED} is on of the flags, then the contents
* for these files will be cached as efficiently as possible so that calls to
* {@link #fetchRemoteContents} will also not need to contact the server. This
* may not be possible for all context providers, so clients cannot assume that
* the above mentioned methods will not be long running. It is still advisable
* for clients to call {@link #refresh} with as much details as possible since, in
* the case where a provider is optimized, performance will be much better.
* </p>
*
* @param traversals the resource traversals that indicate which resources
* are to be refreshed
* @param flags additional refresh behavior. For instance, if
* {@link #FILE_CONTENTS_REQUIRED} is one of the flags, this indicates
* that the client will be accessing the contents of the files covered by
* the traversals. {@link #NONE} should be used when no additional
* behavior is required
* @param monitor a progress monitor, or <code>null</code> if progress
* reporting is not desired
* @exception CoreException if the refresh fails. Reasons include:
* <ul>
* <li>The server could not be contacted for some reason. </li>
* </ul>
*/
public abstract void refresh(ResourceTraversal[] traversals, int flags, IProgressMonitor monitor) throws CoreException;
}