/*******************************************************************************
* Copyright (c) 2000, 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.jdt.core;
import org.eclipse.core.runtime.IProgressMonitor;
/**
* Common protocol for Java 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 Java model as element properties are accessed. The Java 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 Java 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>
*
* @noimplement This interface is not intended to be implemented by clients.
*/
public interface IOpenable {
/**
* 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 Java model does this automatically
* as elements are accessed.
*
* @exception JavaModelException if an error occurs closing this element
*/
public void close() throws JavaModelException;
/**
* Finds and returns the recommended line separator for this element.
* The element's buffer is first searched and the first line separator in this buffer is returned if any.
* Otherwise the preference {@link org.eclipse.core.runtime.Platform#PREF_LINE_SEPARATOR}
* on this element's project or workspace is returned.
* Finally if no such preference is set, the system line separator is returned.
*
* @return the recommended line separator for this element
* @exception JavaModelException if this element does not exist or if an
* exception occurs while accessing its corresponding resource.
* @since 3.2
*/
public String findRecommendedLineSeparator() throws JavaModelException;
/**
* Returns the buffer opened for this element, or <code>null</code>
* if this element does not have a buffer.
*
* @exception JavaModelException 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 JavaModelException;
/**
* 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 JavaModelException 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 JavaModelException;
/**
* 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 JavaModelException 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 JavaModelException;
/**
* 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 ICompilationUnit#reconcile(int, boolean, WorkingCopyOwner, IProgressMonitor)} or
* {@link ICompilationUnit#reconcile(int, boolean, boolean, WorkingCopyOwner, IProgressMonitor)}
* operation will not account for changes which occurred before an
* explicit use of {@link #makeConsistent(IProgressMonitor)}
* <p>
* @param progress the given progress monitor
* @exception JavaModelException if the element is unable to access the contents
* of its underlying resource. Reasons include:
* <ul>
* <li>This Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
* </ul>
* @see IOpenable#isConsistent()
* @see ICompilationUnit#reconcile(int, boolean, WorkingCopyOwner, IProgressMonitor)
*/
void makeConsistent(IProgressMonitor progress) throws JavaModelException;
/**
* 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 Java model does this automatically
* as elements are accessed.
*
* @param progress the given progress monitor
* @exception JavaModelException if an error occurs accessing the contents
* of its underlying resource. Reasons include:
* <ul>
* <li>This Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
* </ul>
*/
public void open(IProgressMonitor progress) throws JavaModelException;
/**
* 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 JavaModelException if an error occurs accessing the contents
* of its underlying resource. Reasons include:
* <ul>
* <li>This Java element does not exist (ELEMENT_DOES_NOT_EXIST)</li>
* <li>This Java element is read-only (READ_ONLY)</li>
* </ul>
*/
public void save(IProgressMonitor progress, boolean force) throws JavaModelException;
}