xml/impl/src/com/intellij/codeInsight/editorActions/EnterBetweenXmlTagsHandler.java

/*
 * Copyright 2000-2014 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.codeInsight.editorActions;

import com.intellij.codeInsight.editorActions.enter.EnterHandlerDelegateAdapter;
import com.intellij.openapi.actionSystem.CommonDataKeys;
import com.intellij.openapi.actionSystem.DataContext;
import com.intellij.openapi.editor.Editor;
import com.intellij.openapi.editor.actionSystem.EditorActionHandler;
import com.intellij.openapi.editor.ex.EditorEx;
import com.intellij.openapi.editor.highlighter.EditorHighlighter;
import com.intellij.openapi.editor.highlighter.HighlighterIterator;
import com.intellij.openapi.project.Project;
import com.intellij.openapi.util.Ref;
import com.intellij.psi.PsiDocumentManager;
import com.intellij.psi.PsiElement;
import com.intellij.psi.PsiFile;
import com.intellij.psi.tree.IElementType;
import com.intellij.psi.xml.XmlFile;
import com.intellij.psi.xml.XmlTag;
import com.intellij.psi.xml.XmlTokenType;
import org.jetbrains.annotations.NotNull;

public class EnterBetweenXmlTagsHandler extends EnterHandlerDelegateAdapter {
  @Override
  public Result preprocessEnter(@NotNull final PsiFile file, @NotNull final Editor editor, @NotNull final Ref<Integer> caretOffset, @NotNull final Ref<Integer> caretAdvance,
                                @NotNull final DataContext dataContext, final EditorActionHandler originalHandler) {
    final Project project = CommonDataKeys.PROJECT.getData(dataContext);
    
    if (file instanceof XmlFile && isBetweenXmlTags(project, editor, file, caretOffset.get().intValue())) {
      originalHandler.execute(editor, dataContext);
      return Result.DefaultForceIndent;
    }
    return Result.Continue;
  }

  private static boolean isBetweenXmlTags(Project project, Editor editor, PsiFile file, int offset) {
    if (offset == 0) return false;
    CharSequence chars = editor.getDocument().getCharsSequence();
    if (chars.charAt(offset - 1) != '>') return false;

    EditorHighlighter highlighter = ((EditorEx)editor).getHighlighter();
    HighlighterIterator iterator = highlighter.createIterator(offset - 1);
    if (iterator.getTokenType() != XmlTokenType.XML_TAG_END) return false;
    
    if (isAtTheEndOfEmptyTag(project, editor, file, iterator)) {
      return false;
    }
    
    iterator.retreat();

    int retrieveCount = 1;
    while(!iterator.atEnd()) {
      final IElementType tokenType = iterator.getTokenType();
      if (tokenType == XmlTokenType.XML_END_TAG_START) return false;
      if (tokenType == XmlTokenType.XML_START_TAG_START) break;
      ++retrieveCount;
      iterator.retreat();
    }

    for(int i = 0; i < retrieveCount; ++i) iterator.advance();
    iterator.advance();
    return !iterator.atEnd() && iterator.getTokenType() == XmlTokenType.XML_END_TAG_START;
  }

  private static boolean isAtTheEndOfEmptyTag(Project project, Editor editor, PsiFile file, HighlighterIterator iterator) {
    if (iterator.getTokenType() != XmlTokenType.XML_TAG_END) {
      return false;
    }

    PsiDocumentManager.getInstance(project).commitDocument(editor.getDocument());
    final PsiElement element = file.findElementAt(iterator.getStart());

    if (element == null) {
      return false;
    }

    final PsiElement parent = element.getParent();
    return parent instanceof XmlTag &&
           parent.getTextRange().getEndOffset() == iterator.getEnd();
  }
}