Add support for creating workspace private project descriptions

Currently importing a project into eclipse requires the creation of a
physical file name .project in the root of the project. this has several
drawbacks for tools that automatically discover projects and import them
for the user as it creates new files and possibly dirty their working
tree. Other tools use a single folder for this purpose or don't require
any permanent files in the working-tree itself. Even Eclipse has already
such concept that is used when a project is located outside the
workspace.

This now adds a new feature called "workspace private project" that only
holds the basic information in the location file in the workspace
directory, any additional information might be needed to restore by a
tool that uses workspace private projects.

Author: laeubi

resources/bundles/org.eclipse.core.resources/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.core.resources; singleton:=true
-Bundle-Version: 3.22.200.qualifier
+Bundle-Version: 3.23.0.qualifier
 Bundle-Activator: org.eclipse.core.resources.ResourcesPlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/LocalMetaArea.java

@@ -347,6 +347,8 @@ public ProjectDescription readOldDescription(IProject project) throws CoreExcept
 	 *        UTF - configName if hasConfigName
 	 *        ... repeat for number of referenced configurations
 	 *      ... repeat for number of build configurations with references
+	 * since 3.23:
+	 *    bool - private flag if project should only be read from its private project configuration
 	 */
 	public void readPrivateDescription(IProject target, ProjectDescription description) {
 		IPath locationFile = locationFor(target).append(F_PROJECT_LOCATION);
@@ -408,6 +410,8 @@ public void readPrivateDescription(IProject target, ProjectDescription descripti
 				m.put(configName, refs);
 			}
 			description.setBuildConfigReferences(m);
+			// read parts since 4.36
+			description.setWorkspacePrivate(dataIn.readBoolean());
 		} catch (IOException e) {
 			//ignore - this is an old location file or an exception occurred
 			// closing the stream
@@ -470,6 +474,7 @@ public void writePrivateDescription(IProject target) throws CoreException {
 					}
 				}
 			}
+			dataOut.writeBoolean(desc.isWorkspacePrivate());
 			output.succeed();
 		} catch (IOException e) {
 			String message = NLS.bind(Messages.resources_exSaveProjectLocation, target.getName());

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/Project.java

@@ -326,7 +326,7 @@ public void create(IProjectDescription description, int updateFlags, IProgressMo
 					updateDescription();
 					// make sure the .location file is written
 					workspace.getMetaArea().writePrivateDescription(this);
-				} else {
+				} else if (!desc.isWorkspacePrivate()) {
 					// write out the project
 					writeDescription(IResource.FORCE);
 				}

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/internal/resources/ProjectDescription.java

@@ -124,6 +124,7 @@ public class ProjectDescription extends ModelObject implements IProjectDescripti
 	protected URI location = null;
 	protected volatile String[] natures = EMPTY_STRING_ARRAY;
 	protected URI snapshotLocation = null;
+	private boolean privateFlag;
 
 	public ProjectDescription() {
 		super();
@@ -978,4 +979,14 @@ private static IProject[] computeDynamicReferencesForProject(IBuildConfiguration
 		}
 		return result.toArray(new IProject[0]);
 	}
+
+	@Override
+	public boolean isWorkspacePrivate() {
+		return privateFlag;
+	}
+
+	@Override
+	public void setWorkspacePrivate(boolean privateFlag) {
+		this.privateFlag = privateFlag;
+	}
 }

resources/bundles/org.eclipse.core.resources/src/org/eclipse/core/resources/IProjectDescription.java

@@ -175,6 +175,13 @@ public interface IProjectDescription {
 	 */
 	ICommand newCommand();
 
+	/**
+	 * @return <code>true</code> if this project is only persisted in the private
+	 *         workspace area
+	 * @since 3.23
+	 */
+	boolean isWorkspacePrivate();
+
 	/**
 	 * Sets the active configuration for the described project.
 	 * <p>
@@ -385,4 +392,12 @@ public interface IProjectDescription {
 	 * @see #getReferencedProjects()
 	 */
 	void setReferencedProjects(IProject[] projects);
+
+	/**
+	 * Sets the project to be only persisted into the private workspace area and not
+	 * into a physical <code>.project</code> file in the root of the project folder.
+	 *
+	 * @since 3.23
+	 */
+	void setWorkspacePrivate(boolean privateFlag);
 }