platform/platform-impl/src/com/intellij/openapi/editor/impl/EditorHighlighterCache.java


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/*
 * Copyright 2000-2013 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.openapi.editor.impl;

import com.intellij.openapi.editor.Document;
import com.intellij.openapi.editor.ex.util.LexerEditorHighlighter;
import com.intellij.openapi.editor.highlighter.EditorHighlighter;
import com.intellij.openapi.util.Key;
import com.intellij.reference.SoftReference;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.lang.ref.WeakReference;

/**
 * @author yole
 */
public class EditorHighlighterCache {
  private static final Key<WeakReference<EditorHighlighter>> ourSomeEditorSyntaxHighlighter = Key.create("some editor highlighter");

  private EditorHighlighterCache() {
  }

  public static void rememberEditorHighlighterForCachesOptimization(Document document, @NotNull final EditorHighlighter highlighter) {
    document.putUserData(ourSomeEditorSyntaxHighlighter, new WeakReference<EditorHighlighter>(highlighter));
  }

  @Nullable
  public static EditorHighlighter getEditorHighlighterForCachesBuilding(Document document) {
    if (document == null) {
      return null;
    }
    final WeakReference<EditorHighlighter> editorHighlighterWeakReference = document.getUserData(ourSomeEditorSyntaxHighlighter);
    final EditorHighlighter someEditorHighlighter = SoftReference.dereference(editorHighlighterWeakReference);

    if (someEditorHighlighter instanceof LexerEditorHighlighter &&
        ((LexerEditorHighlighter)someEditorHighlighter).isValid()
      ) {
      return someEditorHighlighter;
    }
    document.putUserData(ourSomeEditorSyntaxHighlighter, null);
    return null;
  }

}