xml/xml-psi-impl/src/com/intellij/psi/impl/source/xml/XmlEntityCache.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.psi.impl.source.xml;

import com.intellij.openapi.util.Key;
import com.intellij.openapi.util.ModificationTracker;
import com.intellij.psi.*;
import com.intellij.psi.util.CachedValue;
import com.intellij.psi.util.CachedValueProvider;
import com.intellij.psi.util.CachedValuesManager;
import com.intellij.psi.xml.XmlEntityDecl;

import java.util.HashMap;
import java.util.Map;

public class XmlEntityCache {
  private static final Key<Map<String,CachedValue<XmlEntityDecl>>> XML_ENTITY_DECL_MAP = Key.create("XML_ENTITY_DECL_MAP");

  public static void cacheParticularEntity(PsiFile file, XmlEntityDecl decl) {
    synchronized(PsiLock.LOCK) {
      final Map<String, CachedValue<XmlEntityDecl>> cachingMap = getCachingMap(file);
      final String name = decl.getName();
      if (cachingMap.containsKey(name)) return;
      final SmartPsiElementPointer declPointer = SmartPointerManager.getInstance(file.getProject()).createSmartPsiElementPointer(decl);

      cachingMap.put(
        name, CachedValuesManager.getManager(file.getProject()).createCachedValue(new CachedValueProvider<XmlEntityDecl>() {
          @Override
          public Result<XmlEntityDecl> compute() {
            PsiElement declElement = declPointer.getElement();
            if (declElement instanceof XmlEntityDecl && declElement.isValid() && name.equals(((XmlEntityDecl)declElement).getName()))
              return new Result<XmlEntityDecl>((XmlEntityDecl)declElement, declElement);
            cachingMap.put(name,null);
            return new Result<XmlEntityDecl>(null, ModificationTracker.NEVER_CHANGED);
          }
        },
        false
      ));
    }
  }

  static Map<String, CachedValue<XmlEntityDecl>> getCachingMap(final PsiElement targetElement) {
    Map<String, CachedValue<XmlEntityDecl>> map = targetElement.getUserData(XML_ENTITY_DECL_MAP);
    if (map == null){
      map = new HashMap<String,CachedValue<XmlEntityDecl>>();
      targetElement.putUserData(XML_ENTITY_DECL_MAP, map);
    }
    return map;
  }

  public static void copyEntityCaches(final PsiFile file, final PsiFile context) {
    synchronized (PsiLock.LOCK) {
      final Map<String, CachedValue<XmlEntityDecl>> cachingMap = getCachingMap(file);
      for(Map.Entry<String,CachedValue<XmlEntityDecl>> entry:getCachingMap(context).entrySet()) {
        cachingMap.put(entry.getKey(), entry.getValue());
      }
    }

  }

  public static XmlEntityDecl getCachedEntity(PsiFile file, String name) {
    CachedValue<XmlEntityDecl> cachedValue;
    synchronized(PsiLock.LOCK) {
      final Map<String, CachedValue<XmlEntityDecl>> cachingMap = getCachingMap(file);
      cachedValue = cachingMap.get(name);
    }
    return cachedValue != null ? cachedValue.getValue():null;
  }
}