stable elements for any type

xml/dom-impl/src/com/intellij/util/xml/impl/DomManagerImpl.java

@@ -12,6 +12,7 @@ import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.ProjectFileIndex;
 import com.intellij.openapi.roots.ProjectRootManager;
 import com.intellij.openapi.startup.StartupManager;
+import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.util.Disposer;
 import com.intellij.openapi.util.Factory;
 import com.intellij.openapi.util.Key;
@@ -320,7 +321,7 @@ public final class DomManagerImpl extends DomManager {
     }
     final InvocationHandler handler = AdvancedProxy.getInvocationHandler(proxy);
     if (handler instanceof StableInvocationHandler) {
-      final DomElement element = ((StableInvocationHandler)handler).getWrappedElement();
+      final DomElement element = ((StableInvocationHandler<DomElement>)handler).getWrappedElement();
       return element == null ? null : getDomInvocationHandler(element);
     }
     if (handler instanceof DomInvocationHandler) {
@@ -493,9 +494,17 @@ public final class DomManagerImpl extends DomManager {
   }
 
   public final <T extends DomElement> T createStableValue(final Factory<T> provider) {
+    return createStableValue(provider, new Condition<T>() {
+      public boolean value(T t) {
+        return t.isValid();
+      }
+    });
+  }
+
+  public final <T> T createStableValue(final Factory<T> provider, final Condition<T> validator) {
     final T initial = provider.create();
     assert initial != null;
-    final StableInvocationHandler handler = new StableInvocationHandler<T>(initial, provider);
+    final StableInvocationHandler handler = new StableInvocationHandler<T>(initial, provider, validator);
 
     final Set<Class> intf = new HashSet<Class>();
     intf.addAll(Arrays.asList(initial.getClass().getInterfaces()));

xml/dom-impl/src/com/intellij/util/xml/impl/StableInvocationHandler.java

@@ -16,6 +16,7 @@
 package com.intellij.util.xml.impl;
 
 import com.intellij.openapi.util.Comparing;
+import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.util.Factory;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.xml.DomElement;
@@ -33,16 +34,18 @@ import java.util.Set;
 /**
  * @author peter
  */
-class StableInvocationHandler<T extends DomElement> implements InvocationHandler, StableElement {
+class StableInvocationHandler<T> implements InvocationHandler, StableElement {
   private T myOldValue;
   private T myCachedValue;
   private final Set<Class> myClasses;
   private final Factory<T> myProvider;
+  private final Condition<T> myValidator;
 
-  public StableInvocationHandler(final T initial, final Factory<T> provider) {
+  public StableInvocationHandler(final T initial, final Factory<T> provider, Condition<T> validator) {
     myProvider = provider;
     myCachedValue = initial;
     myOldValue = initial;
+    myValidator = validator;
     final Class superClass = initial.getClass().getSuperclass();
     final Set<Class> classes = new HashSet<Class>();
     classes.addAll(Arrays.asList(initial.getClass().getInterfaces()));
@@ -125,7 +128,7 @@ class StableInvocationHandler<T extends DomElement> implements InvocationHandler
     }
   }
 
-  public final DomElement getWrappedElement() {
+  public final T getWrappedElement() {
     if (isNotValid(myCachedValue)) {
       myCachedValue = myProvider.create();
     }
@@ -137,7 +140,7 @@ class StableInvocationHandler<T extends DomElement> implements InvocationHandler
   }
 
   private boolean isNotValid(final T t) {
-    if (t == null || !t.isValid()) return true;
+    if (t == null || !myValidator.value(t)) return true;
     for (final Class aClass : myClasses) {
       if (!aClass.isInstance(t)) return true;
     }

xml/dom-openapi/src/com/intellij/util/xml/DomManager.java

@@ -19,10 +19,7 @@ import com.intellij.openapi.Disposable;
 import com.intellij.openapi.components.ServiceManager;
 import com.intellij.openapi.module.Module;
 import com.intellij.openapi.project.Project;
-import com.intellij.openapi.util.Factory;
-import com.intellij.openapi.util.Key;
-import com.intellij.openapi.util.ModificationTracker;
-import com.intellij.openapi.util.NotNullLazyKey;
+import com.intellij.openapi.util.*;
 import com.intellij.psi.PsiReferenceFactory;
 import com.intellij.psi.xml.XmlAttribute;
 import com.intellij.psi.xml.XmlFile;
@@ -121,6 +118,8 @@ public abstract class DomManager implements ModificationTracker {
    */
   public abstract <T extends DomElement> T createStableValue(Factory<T> provider);
 
+  public abstract <T> T createStableValue(final Factory<T> provider, final Condition<T> validator);
+
   /**
    * Registers a new {@link com.intellij.util.xml.DomFileDescription} within the manager. The description parameter describes some DOM
    * parameters and restrictions to the particular XML files, that need DOM support. Should be called on