platform/extensions/src/com/intellij/openapi/extensions/SmartExtensionPoint.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 package com.intellij.openapi.extensions;
  17
  18 import com.intellij.util.NullableFunction;
  19 import com.intellij.util.containers.ContainerUtil;
  20 import org.jetbrains.annotations.NotNull;
  21 import org.jetbrains.annotations.Nullable;
  22
  23 import java.util.ArrayList;
  24 import java.util.Collection;
  25 import java.util.List;
  26
  27 /**
  28  * @author peter
  29  */
  30 public abstract class SmartExtensionPoint<Extension,V> implements ExtensionPointAndAreaListener<Extension> {
  31   private final Collection<V> myExplicitExtensions;
  32   private ExtensionPoint<Extension> myExtensionPoint;
  33   private List<V> myCache;
  34
  35   protected SmartExtensionPoint(@NotNull final Collection<V> explicitExtensions) {
  36     myExplicitExtensions = explicitExtensions;
  37   }
  38
  39   @NotNull
  40   protected abstract ExtensionPoint<Extension> getExtensionPoint();
  41
  42   public final void addExplicitExtension(@NotNull V extension) {
  43     synchronized (myExplicitExtensions) {
  44       myExplicitExtensions.add(extension);
  45       myCache = null;
  46     }
  47   }
  48
  49   public final void removeExplicitExtension(@NotNull V extension) {
  50     synchronized (myExplicitExtensions) {
  51       myExplicitExtensions.remove(extension);
  52       myCache = null;
  53     }
  54   }
  55
  56   @Nullable
  57   protected abstract V getExtension(@NotNull final Extension extension);
  58
  59   @NotNull
  60   public final List<V> getExtensions() {
  61     synchronized (myExplicitExtensions) {
  62       if (myCache == null) {
  63         myExtensionPoint = getExtensionPoint();
  64         myExtensionPoint.addExtensionPointListener(this);
  65         myCache = new ArrayList<V>(myExplicitExtensions);
  66         myCache.addAll(ContainerUtil.mapNotNull(myExtensionPoint.getExtensions(), new NullableFunction<Extension, V>() {
  67           @Nullable
  68           public V fun(final Extension extension) {
  69             return getExtension(extension);
  70           }
  71         }));
  72       }
  73       return myCache;
  74     }
  75   }
  76
  77   public final void extensionAdded(final Extension extension, @Nullable final PluginDescriptor pluginDescriptor) {
  78     dropCache();
  79   }
  80
  81   public final void dropCache() {
  82     synchronized (myExplicitExtensions) {
  83       if (myCache != null) {
  84         myCache = null;
  85         myExtensionPoint.removeExtensionPointListener(this);
  86         myExtensionPoint = null;
  87       }
  88     }
  89   }
  90
  91   public final void extensionRemoved(final Extension extension, @Nullable final PluginDescriptor pluginDescriptor) {
  92     dropCache();
  93   }
  94
  95   public void areaReplaced(final ExtensionsArea area) {
  96     dropCache();
  97   }
  98 }