xml/dom-openapi/src/com/intellij/util/xml/model/DomModelCache.java

   1 /*
   2  * Copyright 2000-2009 JetBrains s.r.o.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 package com.intellij.util.xml.model;
  18
  19 import com.intellij.openapi.project.Project;
  20 import com.intellij.openapi.util.Key;
  21 import com.intellij.openapi.util.UserDataHolder;
  22 import com.intellij.psi.PsiManager;
  23 import com.intellij.psi.util.CachedValue;
  24 import com.intellij.psi.util.CachedValueProvider;
  25 import com.intellij.psi.util.CachedValuesManager;
  26 import org.jetbrains.annotations.NonNls;
  27 import org.jetbrains.annotations.NotNull;
  28 import org.jetbrains.annotations.Nullable;
  29
  30 /**
  31  * @author Dmitry Avdeev
  32  */
  33 public abstract class DomModelCache<T, H extends UserDataHolder> {
  34
  35   private final Key<CachedValue<T>> myKey;
  36   private final Project myProject;
  37
  38   public DomModelCache(Project project, @NonNls String keyName) {
  39     myProject = project;
  40     myKey = new Key<CachedValue<T>>(keyName);
  41   }
  42
  43   @Nullable
  44   public T getCachedValue(final @NotNull H dataHolder) {
  45     CachedValue<T> cachedValue = dataHolder.getUserData(myKey);
  46     if (cachedValue == null) {
  47       final CachedValueProvider<T> myProvider = new CachedValueProvider<T>() {
  48         @Nullable
  49         public Result<T> compute() {
  50           return computeValue(dataHolder);
  51         }
  52       };
  53       final CachedValuesManager manager = PsiManager.getInstance(myProject).getCachedValuesManager();
  54       cachedValue = manager.createCachedValue(myProvider, false);
  55       dataHolder.putUserData(myKey, cachedValue);
  56     }
  57     return cachedValue.getValue();
  58   }
  59
  60   @NotNull
  61   protected abstract CachedValueProvider.Result<T> computeValue(@NotNull H dataHolder);
  62 }