/*******************************************************************************
* 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.IProgressMonitor;
/**
* Common protocol for script elements that must be opened before they can be
* navigated or modified. Opening a textual element (such as a compilation unit)
* involves opening a buffer on its contents. While open, any changes to the
* buffer can be reflected in the element's structure; see {@link #isConsistent}
* and {@link #makeConsistent(IProgressMonitor)}.
* <p>
* To reduce complexity in clients, elements are automatically opened by the
* script model as element properties are accessed. The script model maintains
* an LRU cache of open elements, and automatically closes elements as they are
* swapped out of the cache to make room for other elements. Elements with
* unsaved changes are never removed from the cache, and thus, if the client
* maintains many open elements with unsaved changes, the LRU cache can grow in
* size (in this case the cache is not bounded). However, as elements are saved,
* the cache will shrink back to its original bounded size.
* </p>
* <p>
* To open an element, all openable parent elements must be open. The script
* model automatically opens parent elements, as it automatically opens
* elements. Opening an element may provide access to direct children and other
* descendants, but does not automatically open any descendents which are
* themselves {@link IOpenable}. For example, opening a compilation unit
* provides access to all its constituent elements, but opening a package
* fragment does not open all compilation units in the package fragment.
* </p>
* <p>
* This interface is not intended to be implemented by clients.
* </p>
*/
public interface IOpenable extends IModelElement {
/**
* Closes this element and its buffer (if any). Closing an element which is
* not open has no effect.
*
* <p>
* Note: although {@link #close} is exposed in the API, clients are not
* expected to open and close elements - the script model does this
* automatically as elements are accessed.
*
* @exception ModelException
* if an error occurs closing this element
*/
public void close() throws ModelException;
/**
* Returns the buffer opened for this element, or <code>null</code> if
* this element does not have a buffer.
*
* @exception ModelException
* if this element does not exist or if an exception occurs
* while accessing its corresponding resource.
* @return the buffer opened for this element, or <code>null</code> if
* this element does not have a buffer
*/
public IBuffer getBuffer() throws ModelException;
/**
* Returns <code>true</code> if this element is open and:
* <ul>
* <li>its buffer has unsaved changes, or
* <li>one of its descendants has unsaved changes, or
* <li>a working copy has been created on one of this element's children
* and has not yet destroyed
* </ul>
*
* @exception ModelException
* if this element does not exist or if an exception occurs
* while accessing its corresponding resource.
* @return <code>true</code> if this element is open and:
* <ul>
* <li>its buffer has unsaved changes, or
* <li>one of its descendants has unsaved changes, or
* <li>a working copy has been created on one of this element's
* children and has not yet destroyed
* </ul>
*/
boolean hasUnsavedChanges() throws ModelException;
/**
* Returns whether the element is consistent with its underlying resource or
* buffer. The element is consistent when opened, and is consistent if the
* underlying resource or buffer has not been modified since it was last
* consistent.
*
* <p>
* NOTE: Child consistency is not considered. For example, a package
* fragment responds <code>true</code> when it knows about all of its
* compilation units present in its underlying folder. However, one or more
* of the compilation units could be inconsistent.
*
* @exception ModelException
* if this element does not exist or if an exception occurs
* while accessing its corresponding resource.
* @return true if the element is consistent with its underlying resource or
* buffer, false otherwise.
* @see IOpenable#makeConsistent(IProgressMonitor)
*/
boolean isConsistent() throws ModelException;
/**
* Returns whether this openable is open. This is a handle-only method.
*
* @return true if this openable is open, false otherwise
*/
boolean isOpen();
/**
* Makes this element consistent with its underlying resource or buffer by
* updating the element's structure and properties as necessary.
* <p>
* Note: Using this functionality on a working copy will interfere with any
* subsequent reconciling operation. Indeed, the next
* {@link ISourceModule#reconcile} operation will not account for changes
* which occurred before an explicit use of
* {@link #makeConsistent(IProgressMonitor)}
* <p>
*
* @param progress
* the given progress monitor
* @exception ModelException
* if the element is unable to access the contents of its
* underlying resource. Reasons include:
* <ul>
* <li>This script element does not exist
* (ELEMENT_DOES_NOT_EXIST)</li>
* </ul>
* @see IOpenable#isConsistent()
* @see ISourceModule#reconcile(int, boolean, WorkingCopyOwner,
* IProgressMonitor)
*/
void makeConsistent(IProgressMonitor progress) throws ModelException;
/**
* Opens this element and all parent elements that are not already open. For
* compilation units, a buffer is opened on the contents of the underlying
* resource.
*
* <p>
* Note: although {@link #open} is exposed in the API, clients are not
* expected to open and close elements - the script model does this
* automatically as elements are accessed.
*
* @param progress
* the given progress monitor
* @exception ModelException
* if an error occurs accessing the contents of its
* underlying resource. Reasons include:
* <ul>
* <li>This script element does not exist
* (ELEMENT_DOES_NOT_EXIST)</li>
* </ul>
*/
public void open(IProgressMonitor progress) throws ModelException;
/**
* Saves any changes in this element's buffer to its underlying resource via
* a workspace resource operation. This has no effect if the element has no
* underlying buffer, or if there are no unsaved changed in the buffer.
* <p>
* The <code>force</code> parameter controls how this method deals with
* cases where the workbench is not completely in sync with the local file
* system. If <code>false</code> is specified, this method will only
* attempt to overwrite a corresponding file in the local file system
* provided it is in sync with the workbench. This option ensures there is
* no unintended data loss; it is the recommended setting. However, if
* <code>true</code> is specified, an attempt will be made to write a
* corresponding file in the local file system, overwriting any existing one
* if need be. In either case, if this method succeeds, the resource will be
* marked as being local (even if it wasn't before).
* <p>
* As a result of this operation, the element is consistent with its
* underlying resource or buffer.
*
* @param progress
* the given progress monitor
* @param force
* it controls how this method deals with cases where the
* workbench is not completely in sync with the local file system
* @exception ModelException
* if an error occurs accessing the contents of its
* underlying resource. Reasons include:
* <ul>
* <li>This script element does not exist
* (ELEMENT_DOES_NOT_EXIST)</li>
* <li>This script element is read-only (READ_ONLY)</li>
* </ul>
*/
public void save(IProgressMonitor progress, boolean force)
throws ModelException;
}