/*
 * Copyright 2000-2009 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.psi.templateLanguages;

import com.intellij.lang.ASTNode;
import com.intellij.psi.FileViewProvider;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiFile;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

/**
 * @author Dmitry Avdeev
 */
public class TemplateLanguageUtil {
  private TemplateLanguageUtil() {
  }

  @Nullable
  public static PsiFile getTemplateFile(PsiFile file) {
    final FileViewProvider viewProvider = file.getViewProvider();
    if (viewProvider instanceof TemplateLanguageFileViewProvider) {
      return viewProvider.getPsi(((TemplateLanguageFileViewProvider)viewProvider).getTemplateDataLanguage());
    } else {
      return null;
    }
  }

  public static PsiFile getBaseFile(@NotNull PsiFile file) {
    FileViewProvider viewProvider = file.getViewProvider();
    return viewProvider.getPsi(viewProvider.getBaseLanguage());
  }

  public static boolean isInsideTemplateFile(@NotNull PsiElement element) {
    return element.getContainingFile().getViewProvider() instanceof TemplateLanguageFileViewProvider;
  }

  public static boolean isTemplateDataFile(@NotNull PsiFile file) {
    FileViewProvider viewProvider = file.getViewProvider();
    return viewProvider instanceof TemplateLanguageFileViewProvider &&
                file == viewProvider.getPsi(((TemplateLanguageFileViewProvider)viewProvider).getTemplateDataLanguage());
  }

  @Nullable
  public static ASTNode getSameLanguageTreePrev(@NotNull ASTNode node) {
    ASTNode current = node.getTreePrev();
    while (current instanceof OuterLanguageElement) {
      current = current.getTreePrev();
    }
    return current;
  }

  @Nullable
  public static ASTNode getSameLanguageTreeNext(@NotNull ASTNode node) {
    ASTNode current = node.getTreeNext();
    while (current instanceof OuterLanguageElement) {
      current = current.getTreeNext();
    }
    return current;
  }
}

@@ -2533,11 +2533,531 @@
 ent;%0A  %7D
+%0A%0A  public static PsiElement getSameLanguageTreePrev(@NotNull PsiElement element) %7B%0A    PsiElement current = element.getNextSibling();%0A    while (current instanceof OuterLanguageElement) %7B%0A      current = current.getPrevSibling();%0A    %7D%0A    return current;%0A  %7D%0A%0A  public static PsiElement getSameLanguageTreeNext(@NotNull PsiElement element) %7B%0A    PsiElement current = element.getNextSibling();%0A    while (current instanceof OuterLanguageElement) %7B%0A      current = current.getNextSibling();%0A    %7D%0A    return current;%0A  %7D
 %0A%7D%0A

Add utility methods