IDEA-63340 Add "find usage" to fields in database [initial]

platform/lang-impl/src/com/intellij/find/findUsages/CustomUsageSearcher.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2000-2011 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.intellij.find.findUsages;
+
+import com.intellij.openapi.extensions.ExtensionPointName;
+import com.intellij.psi.PsiElement;
+import com.intellij.usages.Usage;
+import com.intellij.util.Processor;
+
+/**
+ * @author gregsh
+ */
+public abstract class CustomUsageSearcher {
+  public static final ExtensionPointName<CustomUsageSearcher> EP_NAME = ExtensionPointName.create("com.intellij.customUsageSearcher");
+
+  public abstract void processElementUsages(final PsiElement element, final Processor<Usage> processor, final FindUsagesOptions options);
+}

platform/lang-impl/src/com/intellij/find/findUsages/FindUsagesManager.java

@@ -380,6 +380,14 @@ public class FindUsagesManager implements JDOMExternalizable {
               }
             });
             handler.processElementUsages(element, usageInfoProcessor, options);
+            for (CustomUsageSearcher searcher : Extensions.getExtensions(CustomUsageSearcher.EP_NAME)) {
+              try {
+                searcher.processElementUsages(element, processor, options);
+              }
+              catch (Exception e) {
+                LOG.error(e);
+              }
+            }
           }
 
           Project project = ApplicationManager.getApplication().runReadAction(new Computable<Project>() {

platform/platform-resources/src/META-INF/LangExtensionPoints.xml

@@ -313,6 +313,7 @@
   <extensionPoint name="renameInputValidator" interface="com.intellij.refactoring.rename.RenameInputValidator"/>
 
   <extensionPoint name="findUsagesHandlerFactory" interface="com.intellij.find.findUsages.FindUsagesHandlerFactory" area="IDEA_PROJECT"/>
+  <extensionPoint name="customUsageSearcher" interface="com.intellij.find.findUsages.CustomUsageSearcher"/>
 
   <extensionPoint name="readWriteAccessDetector" interface="com.intellij.codeInsight.highlighting.ReadWriteAccessDetector"/>