Bug 411605: ResourceLookup should honor the PathCanonicalization strategy.

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/resources/FileRelevance.java

@@ -11,12 +11,15 @@
  *******************************************************************************/
 package org.eclipse.cdt.internal.core.resources;
 
+import java.net.URI;
+
 import org.eclipse.cdt.core.model.CoreModel;
 import org.eclipse.cdt.core.model.ICProject;
 import org.eclipse.cdt.internal.core.model.CModelManager;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ResourceAttributes;
+import org.eclipse.core.runtime.IPath;
 
 /**
  * This class computes a relevance for files in case we have to select
@@ -43,6 +46,22 @@ public class FileRelevance {
 	 * @return integer representing file relevance. Larger numbers are more relevant
 	 */
 	public static int getRelevance(IFile f, IProject preferredProject) {
+		return getRelevance(f, preferredProject, true, null);
+	}
+
+	/**
+	 * Compute a relevance for the given file. The higher the score the more relevant the
+	 * file. It is determined by the following criteria: <br>
+	 * - file belongs to preferred project <br>
+	 * - file belongs to a cdt-project <br>
+	 * - file belongs to a source folder of a cdt-project <br>
+	 * - file is accessible
+	 * - file is not a link
+	 * - file matches the original location
+	 * @param f the file to compute the relevance for
+	 * @return integer representing file relevance. Larger numbers are more relevant
+	 */
+	public static int getRelevance(IFile f, IProject preferredProject, boolean degradeSymLinks, Object originalLocation) {
 		int result= 0;
 		IProject p= f.getProject();
 		if (p.equals(preferredProject))
@@ -55,14 +74,24 @@ public class FileRelevance {
 				result+= ON_SOURCE_ROOT;
 		}
 
-		if (!f.isAccessible())
+		if (!f.isAccessible()) {
 			result >>= INACCESSIBLE_SHIFT;
-		else {
+		} else if (f.isLinked()) {
+			result -= LINK_PENALTY;
+		} else if (degradeSymLinks) {
 			ResourceAttributes ra = f.getResourceAttributes();
-			if (f.isLinked() || (ra != null && ra.isSymbolicLink()))
+			if (ra != null && ra.isSymbolicLink())
 				result -= LINK_PENALTY;
+		} else {
+			// Symbolic links are not degraded, prefer the original location
+			if (originalLocation instanceof URI) {
+				if (originalLocation.equals(f.getLocationURI()))
+					result += LINK_PENALTY;
+			} else if (originalLocation instanceof IPath) {
+				if (originalLocation.equals(f.getLocation()))
+					result+= LINK_PENALTY;
+			}
 		}
-
 		return result;
 	}
 }

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/resources/PathCanonicalizationStrategy.java

@@ -29,6 +29,10 @@ public abstract class PathCanonicalizationStrategy {
 	public static String getCanonicalPath(File file) {
 		return instance.getCanonicalPathInternal(file);
 	}
+	
+	public static boolean resolvesSymbolicLinks() {
+		return instance.resolvesSymbolicLinksInternal();
+	}
 
 	/**
 	 * Sets path canonicalization strategy. If <code>canonicalize</code> is <code>true</code>,
@@ -49,6 +53,11 @@ public abstract class PathCanonicalizationStrategy {
 						return file.getAbsolutePath();
 					}
 				}
+
+				@Override
+				protected boolean resolvesSymbolicLinksInternal() {
+					return true;
+				}
 			};
 		} else {
 			instance = new PathCanonicalizationStrategy() {
@@ -56,9 +65,15 @@ public abstract class PathCanonicalizationStrategy {
 				protected String getCanonicalPathInternal(File file) {
 					return file.getAbsolutePath();
 				}
+
+				@Override
+				protected boolean resolvesSymbolicLinksInternal() {
+					return false;
+				}
 			};
 		}
 	}
 
 	protected abstract String getCanonicalPathInternal(File file);
+	protected abstract boolean resolvesSymbolicLinksInternal();
 }

core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/resources/ResourceLookup.java

@@ -75,7 +75,7 @@ public class ResourceLookup {
 	 * 			NB the returned IFile may not exist
 	 */
 	public static IFile selectFileForLocationURI(URI location, IProject preferredProject) {
-		return selectFile(findFilesForLocationURI(location), preferredProject);
+		return selectFile(findFilesForLocationURI(location), preferredProject, location);
 	}
 
 	/**
@@ -88,10 +88,20 @@ public class ResourceLookup {
 	 * 			NB the returned IFile may not exist
 	 */
 	public static IFile selectFileForLocation(IPath location, IProject preferredProject) {
-		return selectFile(findFilesForLocation(location), preferredProject);
+		return selectFile(findFilesForLocation(location), preferredProject, location);
 	}
 
-	private static IFile selectFile(IFile[] files, IProject preferredProject) {
+	/**
+	 * Iterates through a list of 'file' resources, and selects the one with the highest "relevance score". 
+	 * 
+	 * NOTE: To compute the "relevance scores" this method may cause additional project-descriptions to load.
+	 * To avoid the expense of loading additional project-descriptions, we first perform a quick first-pass 
+	 * through the list of IFiles (which would normally be a very small list), to see if any of them is in 
+	 * the preferred project. In other words, if we know that the file within the preferred project is the 
+	 * one that's most relevant, then first try to find it directly - before getting to the more expensive 
+	 * loop of computing the "relevance scores" for all the files.
+	 */
+	private static IFile selectFile(IFile[] files, IProject preferredProject, Object originalLocation) {
 		if (files.length == 0)
 			return null;
 
@@ -101,9 +111,8 @@ public class ResourceLookup {
 		IFile best= null;
 		int bestRelevance= -1;
 
-		for (int i = 0; i < files.length; i++) {
+		for (IFile file : files) {
-			IFile file = files[i];
+			int relevance= FileRelevance.getRelevance(file, preferredProject, PathCanonicalizationStrategy.resolvesSymbolicLinks(), originalLocation);
-			int relevance= FileRelevance.getRelevance(file, preferredProject);
 			if (best == null || relevance > bestRelevance ||
 					(relevance == bestRelevance &&
 							best.getFullPath().toString().compareTo(file.getFullPath().toString()) > 0)) {