From 591634c8c5ff09ec33e39d15654ae9cc5f9680e6 Mon Sep 17 00:00:00 2001
From: Dmitry Jemerov <yole@jetbrains.com>
Date: Fri, 9 Mar 2018 18:23:38 +0100
Subject: [PATCH] Notify folding listener about folding region removal

---
 .../openapi/editor/ex/FoldingListener.java    | 30 ++++++++-----------
 .../openapi/editor/impl/FoldingModelImpl.java |  8 +++++
 2 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/platform/platform-impl/src/com/intellij/openapi/editor/ex/FoldingListener.java b/platform/platform-impl/src/com/intellij/openapi/editor/ex/FoldingListener.java
index 5ca4ee4c1ab6..5d637442ed83 100644
--- a/platform/platform-impl/src/com/intellij/openapi/editor/ex/FoldingListener.java
+++ b/platform/platform-impl/src/com/intellij/openapi/editor/ex/FoldingListener.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2010 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.
- */
+// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.openapi.editor.ex;
 
 import com.intellij.openapi.editor.FoldRegion;
@@ -27,17 +13,25 @@ import org.jetbrains.annotations.NotNull;
 public interface FoldingListener {
 
   /**
-   * Informs that {@code 'collapsed'} state of given fold region is just changed.
+   * Informs that {@code 'collapsed'} state of given fold region is just changed, or that the given fold region has just been created.
    * <p/>
    * <b>Note:</b> listener should delay fold region state processing until {@link #onFoldProcessingEnd()} is called.
    * I.e. folding model may return inconsistent data between current moment and {@link #onFoldProcessingEnd()}.
    *
    * @param region    fold region that is just collapsed or expanded
    */
-  void onFoldRegionStateChange(@NotNull FoldRegion region);
+  default void onFoldRegionStateChange(@NotNull FoldRegion region) {
+  }
+
+  /**
+   * Informs that the given fold region is about to be removed.
+   */
+  default void beforeFoldRegionRemoved(@NotNull FoldRegion region) {
+  }
 
   /**
    * Informs that fold processing is done.
    */
-  void onFoldProcessingEnd();
+  default void onFoldProcessingEnd() {
+  }
 }
diff --git a/platform/platform-impl/src/com/intellij/openapi/editor/impl/FoldingModelImpl.java b/platform/platform-impl/src/com/intellij/openapi/editor/impl/FoldingModelImpl.java
index 9cd09e590eb6..7040c5b6cb9d 100644
--- a/platform/platform-impl/src/com/intellij/openapi/editor/impl/FoldingModelImpl.java
+++ b/platform/platform-impl/src/com/intellij/openapi/editor/impl/FoldingModelImpl.java
@@ -271,6 +271,7 @@ public class FoldingModelImpl implements FoldingModelEx, PrioritizedInternalDocu
 
     ((FoldRegionImpl)region).setExpanded(true, false);
     notifyListenersOnFoldRegionStateChange(region);
+    notifyListenersOnFoldRegionRemove(region);
 
     myFoldRegionsProcessed = true;
     region.dispose();
@@ -304,6 +305,7 @@ public class FoldingModelImpl implements FoldingModelEx, PrioritizedInternalDocu
     FoldRegion[] regions = getAllFoldRegions();
     for (FoldRegion region : regions) {
       if (!region.isExpanded()) notifyListenersOnFoldRegionStateChange(region);
+      notifyListenersOnFoldRegionRemove(region);
       region.dispose();
     }
     doClearFoldRegions();
@@ -591,6 +593,12 @@ public class FoldingModelImpl implements FoldingModelEx, PrioritizedInternalDocu
     }
   }
 
+  private void notifyListenersOnFoldRegionRemove(@NotNull FoldRegion foldRegion) {
+    for (FoldingListener listener : myListeners) {
+      listener.beforeFoldRegionRemoved(foldRegion);
+    }
+  }
+
   @NotNull
   @Override
   public String dumpState() {