bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/LegacyResourceSupport.java

/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ui.internal;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.Platform;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.ui.internal.util.BundleUtility;
import org.osgi.framework.Bundle;

/**
 * Provides access to resource-specific classes, needed to provide backwards
 * compatibility for resource-specific functions which could not be moved up
 * from the generic workbench layer to the IDE layer.
 */
public final class LegacyResourceSupport {

	private static String[] resourceClassNames = { "org.eclipse.core.resources.IResource", //$NON-NLS-1$
			"org.eclipse.core.resources.IContainer", //$NON-NLS-1$
			"org.eclipse.core.resources.IFolder", //$NON-NLS-1$
			"org.eclipse.core.resources.IProject", //$NON-NLS-1$
			"org.eclipse.core.resources.IFile", //$NON-NLS-1$
	};

	/**
	 * Cached value of
	 * <code>Class.forName("org.eclipse.core.resources.IResource")</code>;
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.0
	 */
	private static Class<?> iresourceClass = null;

	/**
	 * Cached value of
	 * <code>Class.forName("org.eclipse.core.resources.IFile")</code>;
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.1
	 */
	private static Class<?> ifileClass;

	/**
	 * Cached value of
	 * <code>Class.forName("org.eclipse.ui.IContributorResourceAdapter")</code>;
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.0
	 */
	private static Class<?> icontributorResourceAdapterClass = null;

	/**
	 * Cached value of <code>
	 * org.eclipse.ui.IContributorResourceAdapter.getAdaptedResource(IAdaptable)
	 * </code> <code>null</code> if not initialized or not present.
	 *
	 * @since 3.3
	 */
	private static Method getAdaptedResourceMethod = null;

	/**
	 * Cached value of <code>
	 * org.eclipse.ui.IContributorResourceAdapter2.getAdaptedResourceMapping(IAdaptable)
	 * </code> <code>null</code> if not initialized or not present.
	 *
	 * @since 3.3
	 */
	private static Method getAdaptedResourceMappingMethod = null;

	/**
	 * Cached value of
	 * <code>Class.forName("org.eclipse.ui.ide.IContributorResourceAdapter2")</code>;
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.1
	 */
	private static Class<?> icontributorResourceAdapter2Class = null;

	/**
	 * Cached value of
	 * <code>Class.forName("org.eclipse.ui.internal.ide.DefaultContributorResourceAdapter")</code>;
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.0
	 */
	private static Class<?> defaultContributorResourceAdapterClass = null;

	/**
	 * Cached value for reflective result of
	 * <code>DefaultContributorRessourceAdapter.getDefault()</code>.
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.3
	 */
	private static Object defaultContributorResourceAdapter = null;

	/**
	 * Cached value of
	 * <code>Class.forName("org.eclipse.core.resources.mapping.ResourceMappingr")</code>;
	 * <code>null</code> if not initialized or not present.
	 *
	 * @since 3.0
	 */
	private static Class<?> resourceMappingClass = null;

	/**
	 * Indicates whether the IDE plug-in (which supplies the resource contribution
	 * adapters) is even around.
	 */
	private static boolean resourceAdapterPossible = true;

	/**
	 * Returns <code>IFile.class</code> or <code>null</code> if the class is not
	 * available.
	 * <p>
	 * This method exists to avoid explicit references from the generic workbench to
	 * the resources plug-in.
	 * </p>
	 *
	 * @return <code>IFile.class</code> or <code>null</code> if class not available
	 * @since 3.1
	 */
	public static Class<?> getFileClass() {
		if (ifileClass != null) {
			// tried before and succeeded
			return ifileClass;
		}
		Class<?> c = loadClass("org.eclipse.core.resources", "org.eclipse.core.resources.IFile"); //$NON-NLS-1$ //$NON-NLS-2$
		if (c != null) {
			// The class was found so record it
			ifileClass = c;
		}
		return c;
	}

	/**
	 * Returns <code>IResource.class</code> or <code>null</code> if the class is not
	 * available.
	 * <p>
	 * This method exists to avoid explicit references from the generic workbench to
	 * the resources plug-in.
	 * </p>
	 *
	 * @return <code>IResource.class</code> or <code>null</code> if class not
	 *         available
	 * @since 3.0
	 */
	public static Class<?> getResourceClass() {
		if (iresourceClass != null) {
			// tried before and succeeded
			return iresourceClass;
		}
		Class<?> c = loadClass("org.eclipse.core.resources", "org.eclipse.core.resources.IResource"); //$NON-NLS-1$ //$NON-NLS-2$
		if (c != null) {
			// The class was found so record it
			iresourceClass = c;
		}
		return c;
	}

	/**
	 * Returns <code>ResourceMapping.class</code> or <code>null</code> if the class
	 * is not available.
	 * <p>
	 * This method exists to avoid explicit references from the generic workbench to
	 * the resources plug-in.
	 * </p>
	 *
	 * @return <code>ResourceMapping.class</code> or <code>null</code> if class not
	 *         available
	 * @since 3.1
	 */
	public static Class<?> getResourceMappingClass() {
		if (resourceMappingClass != null) {
			// tried before and succeeded
			return resourceMappingClass;
		}
		Class<?> c = loadClass("org.eclipse.core.resources", "org.eclipse.core.resources.mapping.ResourceMapping"); //$NON-NLS-1$ //$NON-NLS-2$
		if (c != null) {
			// The class was found so record it
			resourceMappingClass = c;
		}
		return c;
	}

	/**
	 * Returns <code>IContributorResourceAdapter.class</code> or <code>null</code>
	 * if the class is not available.
	 * <p>
	 * This method exists to avoid explicit references from the generic workbench to
	 * the IDE plug-in.
	 * </p>
	 *
	 * @return <code>IContributorResourceAdapter.class</code> or <code>null</code>
	 *         if class not available
	 * @since 3.0
	 */
	public static Class<?> getIContributorResourceAdapterClass() {
		if (icontributorResourceAdapterClass != null) {
			// tried before and succeeded
			return icontributorResourceAdapterClass;
		}
		Class<?> c = loadClass("org.eclipse.ui.ide", "org.eclipse.ui.IContributorResourceAdapter"); //$NON-NLS-1$ //$NON-NLS-2$
		if (c != null) {
			// The class was found so record it
			icontributorResourceAdapterClass = c;
		}
		return c;
	}

	/**
	 * Returns <code>IContributorResourceAdapter2.class</code> or <code>null</code>
	 * if the class is not available.
	 * <p>
	 * This method exists to avoid explicit references from the generic workbench to
	 * the IDE plug-in.
	 * </p>
	 *
	 * @return <code>IContributorResourceAdapter.class</code> or <code>null</code>
	 *         if class not available
	 * @since 3.1
	 */
	public static Class<?> getIContributorResourceAdapter2Class() {
		if (icontributorResourceAdapter2Class != null) {
			// tried before and succeeded
			return icontributorResourceAdapter2Class;
		}
		Class<?> c = loadClass("org.eclipse.ui.ide", "org.eclipse.ui.ide.IContributorResourceAdapter2"); //$NON-NLS-1$ //$NON-NLS-2$
		if (c != null) {
			// The class was found so record it
			icontributorResourceAdapter2Class = c;
		}
		return c;
	}

	private static Class<?> loadClass(String bundleName, String className) {
		if (!resourceAdapterPossible) {
			// tried before and failed
			return null;
		}
		Bundle bundle = Platform.getBundle(bundleName);
		if (bundle == null) {
			// Required plug-in is not around
			// assume that it will never be around
			resourceAdapterPossible = false;
			return null;
		}
		// Required plug-in is around
		// it's not our job to activate the plug-in
		if (!BundleUtility.isActivated(bundle)) {
			// assume it might come alive later
			resourceAdapterPossible = true;
			return null;
		}
		try {
			return bundle.loadClass(className);
		} catch (ClassNotFoundException e) {
			// unable to load the class - sounds pretty serious
			// treat as if the plug-in were unavailable
			resourceAdapterPossible = false;
			return null;
		}
	}

	/**
	 * Returns <code>DefaultContributorResourceAdapter.class</code> or
	 * <code>null</code> if the class is not available.
	 * <p>
	 * This method exists to avoid explicit references from the generic workbench to
	 * the IDE plug-in.
	 * </p>
	 *
	 * @return <code>DefaultContributorResourceAdapter.class</code> or
	 *         <code>null</code> if class not available
	 * @since 3.0
	 */
	public static Class<?> getDefaultContributorResourceAdapterClass() {
		if (defaultContributorResourceAdapterClass != null) {
			// tried before and succeeded
			return defaultContributorResourceAdapterClass;
		}
		Class<?> c = loadClass("org.eclipse.ui.ide", "org.eclipse.ui.internal.ide.DefaultContributorResourceAdapter"); //$NON-NLS-1$ //$NON-NLS-2$
		if (c != null) {
			// The class was found so record it
			defaultContributorResourceAdapterClass = c;
		}
		return c;
	}

	private static Object getDefaultContributorResourceAdapter() {
		if (defaultContributorResourceAdapter != null) {
			return defaultContributorResourceAdapter;
		}

		// reflective equivalent of
		// resourceAdapter = DefaultContributorResourceAdapter.getDefault();

		Class<?> c = LegacyResourceSupport.getDefaultContributorResourceAdapterClass();
		if (c != null) {
			try {
				Method m = c.getDeclaredMethod("getDefault");//$NON-NLS-1$
				defaultContributorResourceAdapter = m.invoke(null);
				return defaultContributorResourceAdapter;
			} catch (SecurityException | NoSuchMethodException | IllegalArgumentException | IllegalAccessException | InvocationTargetException e) {
				// shouldn't happen - but play it safe
			}

		}

		return null;

	}

	/**
	 * Returns <code>true</code> if the provided type name is an
	 * <code>IResource</code>, and <code>false</code> otherwise.
	 *
	 * @param objectClassName
	 * @return <code>true</code> if the provided type name is an
	 *         <code>IResource</code>, and <code>false</code> otherwise.
	 *
	 * @since 3.1
	 */
	public static boolean isResourceType(String objectClassName) {
		for (String resourceClassName : resourceClassNames) {
			if (resourceClassName.equals(objectClassName)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Returns <code>true</code> if the provided type name is an
	 * <code>"org.eclipse.core.resources.mapping.ResourceMapping"</code>, and
	 * <code>false</code> otherwise.
	 *
	 * @param objectClassName
	 * @return <code>true</code> if the provided type name is an
	 *         <code>"org.eclipse.core.resources.mapping.ResourceMapping"</code>,
	 *         and <code>false</code> otherwise.
	 *
	 * @since 3.1
	 */
	public static boolean isResourceMappingType(String objectClassName) {
		return objectClassName.equals("org.eclipse.core.resources.mapping.ResourceMapping"); //$NON-NLS-1$
	}

	/**
	 * Returns the class search order starting with <code>extensibleClass</code>.
	 * The search order is defined in this class' comment.
	 *
	 * @since 3.1
	 */
	private static boolean isInstanceOf(Class<?> clazz, String type) {
		if (clazz.getName().equals(type)) {
			return true;
		}
		Class<?> superClass = clazz.getSuperclass();
		if (superClass != null && isInstanceOf(superClass, type)) {
			return true;
		}
		Class<?>[] interfaces = clazz.getInterfaces();
		for (Class<?> currentInterface : interfaces) {
			if (isInstanceOf(currentInterface, type)) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Returns the adapted resource using the
	 * <code>IContributorResourceAdapter</code> registered for the given object. If
	 * the Resources plug-in is not loaded the object can not be adapted.
	 *
	 * @param object the object to adapt to <code>IResource</code>.
	 * @return returns the adapted resource using the
	 *         <code>IContributorResourceAdapter</code> or <code>null</code> if the
	 *         Resources plug-in is not loaded.
	 *
	 * @since 3.1
	 */
	public static Object getAdaptedContributorResource(Object object) {
		Class<?> resourceClass = LegacyResourceSupport.getResourceClass();
		if (resourceClass == null) {
			return null;
		}
		if (resourceClass.isInstance(object)) {
			return null;
		}
		if (object instanceof IAdaptable) {
			IAdaptable adaptable = (IAdaptable) object;
			Class<?> contributorResourceAdapterClass = LegacyResourceSupport.getIContributorResourceAdapterClass();
			if (contributorResourceAdapterClass == null) {
				return adaptable.getAdapter(resourceClass);
			}
			Object resourceAdapter = adaptable.getAdapter(contributorResourceAdapterClass);
			if (resourceAdapter == null) {
				resourceAdapter = LegacyResourceSupport.getDefaultContributorResourceAdapter();
				if (resourceAdapter == null) {
					return null;
				}
			}
			// reflective equivalent of
			// result = ((IContributorResourceAdapter)
			// resourceAdapter).getAdaptedResource(adaptable);

			Method m = getContributorResourceAdapterGetAdaptedResourceMethod();
			if (m != null) {
				try {
					return m.invoke(resourceAdapter, adaptable);
				} catch (IllegalArgumentException | IllegalAccessException | InvocationTargetException e) {
					// shouldn't happen - but play it safe
				}
			}

		}
		return null;
	}

	private static Method getContributorResourceAdapterGetAdaptedResourceMethod() {
		if (getAdaptedResourceMethod != null) {
			return getAdaptedResourceMethod;
		}

		Class<?> c = getIContributorResourceAdapterClass();
		if (c != null) {
			try {
				getAdaptedResourceMethod = c.getDeclaredMethod("getAdaptedResource", new Class[] { IAdaptable.class }); //$NON-NLS-1$
				return getAdaptedResourceMethod;
			} catch (SecurityException | NoSuchMethodException e) {
				// shouldn't happen - but play it safe
			}

		}

		return null;
	}

	private static Method getContributorResourceAdapter2GetAdaptedResourceMappingMethod() {
		if (getAdaptedResourceMappingMethod != null) {
			return getAdaptedResourceMappingMethod;
		}

		Class<?> c = getIContributorResourceAdapter2Class();
		if (c != null) {
			try {
				getAdaptedResourceMappingMethod = c.getDeclaredMethod("getAdaptedResourceMapping", //$NON-NLS-1$
						new Class<?>[] { IAdaptable.class });
				return getAdaptedResourceMappingMethod;
			} catch (SecurityException | NoSuchMethodException e) {
				// do nothing - play it safe
			}

		}

		return null;
	}

	/**
	 * Returns the adapted resource mapping using the
	 * <code>IContributorResourceAdapter2</code> registered for the given object. If
	 * the Resources plug-in is not loaded the object can not be adapted.
	 *
	 * @param object the object to adapt to <code>ResourceMapping</code>.
	 * @return returns the adapted resource using the
	 *         <code>IContributorResourceAdapter2</code> or <code>null</code> if the
	 *         Resources plug-in is not loaded.
	 *
	 * @since 3.1
	 */
	public static Object getAdaptedContributorResourceMapping(Object object) {
		Class<?> resourceMappingClass = LegacyResourceSupport.getResourceMappingClass();
		if (resourceMappingClass == null) {
			return null;
		}
		if (resourceMappingClass.isInstance(object)) {
			return null;
		}
		if (object instanceof IAdaptable) {
			IAdaptable adaptable = (IAdaptable) object;
			Class<?> contributorResourceAdapterClass = LegacyResourceSupport.getIContributorResourceAdapterClass();
			if (contributorResourceAdapterClass == null) {
				return adaptable.getAdapter(resourceMappingClass);
			}
			Class<?> contributorResourceAdapter2Class = LegacyResourceSupport.getIContributorResourceAdapter2Class();
			if (contributorResourceAdapter2Class == null) {
				return adaptable.getAdapter(resourceMappingClass);
			}
			Object resourceAdapter = adaptable.getAdapter(contributorResourceAdapterClass);
			Object resourceMappingAdapter;
			if (resourceAdapter != null && contributorResourceAdapter2Class.isInstance(resourceAdapter)) {
				// The registered adapter also handles resource mappings
				resourceMappingAdapter = resourceAdapter;
			} else {
				// Either there is no registered adapter or it doesn't handle resource mappings.
				// In this case, we will use the default contribution adapter
				resourceMappingAdapter = getDefaultContributorResourceAdapter();
				if (resourceMappingAdapter == null) {
					return null;
				}
			}

			// reflective equivalent of
			// result = ((IContributorResourceAdapter2)
			// resourceAdapter).getAdaptedResource(adaptable);

			Method m = getContributorResourceAdapter2GetAdaptedResourceMappingMethod();
			if (m != null) {

				try {
					Object result = m.invoke(resourceMappingAdapter, adaptable);
					if (result != null) {
						return result;
					}
				} catch (IllegalArgumentException | IllegalAccessException | InvocationTargetException e) {
					// shouldn't happen - but play it safe
				}

			}

			// If we get here, that means that the object in question doesn't adapt to
			// resource mapping
			// and it's contributed adapter doesn't do the adaptation either.
			// Before we fail, we will attempt to adapt the object to IResource and then to
			// ResourceMapping
			Object r = getAdaptedContributorResource(object);
			if (r != null) {
				return Platform.getAdapterManager().getAdapter(r, resourceMappingClass);
			}

			// we've exhausted every avenue so just return null
			return null;
		}
		// Fallback to querying the adapter manager directly when the object isn't an
		// IAdaptable
		return Platform.getAdapterManager().getAdapter(object, resourceMappingClass);
	}

	/**
	 * Adapts a selection to the given objectClass considering the Legacy resource
	 * support. Non resource objectClasses are adapted using the
	 * <code>IAdapterManager</code> and this may load the plug-in that contributes
	 * the adapter factory.
	 * <p>
	 * The returned selection will only contain elements successfully adapted.
	 * </p>
	 *
	 * @param selection   the selection to adapt
	 * @param objectClass the class name to adapt the selection to
	 * @return an adapted selection
	 *
	 * @since 3.1
	 */
	public static IStructuredSelection adaptSelection(IStructuredSelection selection, String objectClass) {
		List<Object> newSelection = new ArrayList<>(10);
		for (Object element : selection) {
			Object adaptedElement = getAdapter(element, objectClass);
			if (adaptedElement != null) {
				newSelection.add(adaptedElement);
			}
		}
		return new StructuredSelection(newSelection);
	}

	/**
	 * Adapts an object to a specified objectClass considering the Legacy resource
	 * support. Non resource objectClasses are adapted using the
	 * <code>IAdapterManager</code> and this may load the plug-in that contributes
	 * the adapter factory.
	 * <p>
	 * The returned selection will be of the same size as the original, and elements
	 * that could not be adapted are added to the returned selection as is.
	 * </p>
	 *
	 * @param element     the element to adapt
	 * @param objectClass the class name to adapt the selection to
	 * @return an adapted element or <code>null</code> if the element could not be
	 *         adapted.
	 *
	 * @since 3.1
	 */
	public static Object getAdapter(Object element, String objectClass) {
		Object adaptedElement = null;
		if (isInstanceOf(element.getClass(), objectClass)) {
			adaptedElement = element;
		} else // Handle IResource
		if (LegacyResourceSupport.isResourceType(objectClass)) {
			adaptedElement = getAdaptedResource(element);
		} else if (LegacyResourceSupport.isResourceMappingType(objectClass)) {
			adaptedElement = getAdaptedResourceMapping(element);
			if (adaptedElement == null) {
				// The object doesn't adapt directly so check if it adapts transitively
				Object resource = getAdaptedResource(element);
				if (resource != null) {
					adaptedElement = ((IAdaptable) resource)
							.getAdapter(LegacyResourceSupport.getResourceMappingClass());
				}
			}
		} else {
			// Handle all other types by using the adapter factory.
			adaptedElement = Platform.getAdapterManager().loadAdapter(element, objectClass);
		}
		return adaptedElement;
	}

	/**
	 * Adapt the given element to an <code>IResource</code> using the following
	 * search order:
	 * <ol>
	 * <li>using the IContributorResourceAdapter registered for the given element,
	 * or
	 * <li>directly asking the element if it adapts.
	 * </ol>
	 *
	 * @param element the element to adapt
	 * @return an <code>IResource</code> instance if the element could be adapted or
	 *         <code>null</code> otherwise.
	 * @since 3.1
	 */
	public static Object getAdaptedResource(Object element) {
		Class<?> resourceClass = LegacyResourceSupport.getResourceClass();
		Object adaptedValue = null;
		if (resourceClass != null) {
			if (resourceClass.isInstance(element)) {
				adaptedValue = element;
			} else {
				adaptedValue = LegacyResourceSupport.getAdaptedContributorResource(element);
			}
		}
		return adaptedValue;
	}

	/**
	 * Adapt the given element to an <code>ResourceMapping</code> using the
	 * following search order:
	 * <ol>
	 * <li>using the IContributorResourceAdapter2 registered for the given element,
	 * or
	 * <li>directly asking the element if it adapts.
	 * </ol>
	 *
	 * @param element the element to adapt
	 * @return an <code>ResourceMapping</code> instance if the element could be
	 *         adapted or <code>null</code> otherwise.
	 * @since 3.1
	 */
	public static Object getAdaptedResourceMapping(Object element) {
		Class<?> resourceMappingClass = LegacyResourceSupport.getResourceMappingClass();
		Object adaptedValue = null;
		if (resourceMappingClass != null) {
			if (resourceMappingClass.isInstance(element)) {
				adaptedValue = element;
			} else {
				adaptedValue = LegacyResourceSupport.getAdaptedContributorResourceMapping(element);
			}
		}
		return adaptedValue;
	}

	/**
	 * Prevents construction
	 */
	private LegacyResourceSupport() {
		// do nothing
	}

}