introduced FileTypeSpecificInputFilter for index to expose its applicability to specific file types and reasonable default implementation to be used

platform/indexing-api/src/com/intellij/util/indexing/DefaultFileTypeSpecificInputFilter.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2000-2013 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.util.indexing;
+
+import com.intellij.openapi.fileTypes.FileType;
+import com.intellij.openapi.vfs.VirtualFile;
+import com.intellij.util.Consumer;
+import org.jetbrains.annotations.NotNull;
+
+public class DefaultFileTypeSpecificInputFilter implements FileBasedIndex.FileTypeSpecificInputFilter {
+  private FileType[] myFileTypes;
+
+  public DefaultFileTypeSpecificInputFilter(@NotNull FileType... fileTypes) {
+    myFileTypes = fileTypes;
+  }
+
+  public void registerFileTypesUsedForIndexing(@NotNull Consumer<FileType> fileTypeSink) {
+    for(FileType ft:myFileTypes) fileTypeSink.consume(ft);
+  }
+
+  @Override
+  public boolean acceptInput(VirtualFile file) {
+    return true;
+  }
+}

platform/indexing-api/src/com/intellij/util/indexing/FileBasedIndex.java

@@ -17,6 +17,7 @@ package com.intellij.util.indexing;
 
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.components.BaseComponent;
+import com.intellij.openapi.fileTypes.FileType;
 import com.intellij.openapi.progress.ProgressIndicator;
 import com.intellij.openapi.project.Project;
 import com.intellij.openapi.roots.ContentIterator;
@@ -24,6 +25,7 @@ import com.intellij.openapi.util.Condition;
 import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.openapi.vfs.VirtualFileWithId;
 import com.intellij.psi.search.GlobalSearchScope;
+import com.intellij.util.Consumer;
 import com.intellij.util.Processor;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
@@ -133,7 +135,11 @@ public abstract class FileBasedIndex implements BaseComponent {
   /**
   * Author: dmitrylomov
   */
-  public static interface InputFilter {
+  public interface InputFilter {
     boolean acceptInput(VirtualFile file);
   }
+
+  public interface FileTypeSpecificInputFilter extends InputFilter {
+    void registerFileTypesUsedForIndexing(@NotNull Consumer<FileType> fileTypeSink);
+  }
 }