Folding group support. Fix CWM-172

GitOrigin-RevId: d98f91df51eacefe93ec322a851799a0802c62d7

platform/core-api/src/com/intellij/openapi/editor/FoldingGroup.java

@@ -1,24 +1,53 @@
 // Copyright 2000-2020 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;
 
+import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NonNls;
 
+import java.util.concurrent.atomic.AtomicLong;
+
 /**
  * {@link com.intellij.openapi.editor.FoldRegion}s with same FoldingGroup instances expand and collapse together.
  *
  * @author peter
  */
 public final class FoldingGroup {
+  private static final AtomicLong ourCounter = new AtomicLong();
+
   @NonNls private final String myDebugName;
+  private final long myId;
 
   private FoldingGroup(@NonNls String debugName) {
     myDebugName = debugName;
+    myId = ourCounter.incrementAndGet();
   }
 
   public static FoldingGroup newGroup(@NonNls String debugName) {
     return new FoldingGroup(debugName);
   }
 
+  @ApiStatus.Internal
+  public long getId() {
+    return myId;
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) return true;
+    if (o == null || getClass() != o.getClass()) return false;
+
+    FoldingGroup group = (FoldingGroup)o;
+
+    if (myId != group.myId) return false;
+
+    return true;
+  }
+
+  @Override
+  public int hashCode() {
+    return (int)(myId ^ (myId >>> 32));
+  }
+
   @Override
   public String toString() {
     return myDebugName;

platform/lang-impl/src/com/intellij/codeInsight/folding/impl/UpdateFoldRegionsOperation.java

@@ -199,14 +199,16 @@ final class UpdateFoldRegionsOperation implements Runnable {
       List<FoldRegion> regionsToProcess = group == null ? Collections.singletonList(region) : foldingModel.getGroupedRegions(group);
       matchedInfos.clear();
       boolean shouldRemove = false;
+      boolean isLight = true;
       for (FoldRegion regionToProcess : regionsToProcess) {
         if (!regionToProcess.isValid() || shouldRemoveRegion(regionToProcess, info, rangeToExpandStatusMap, infoRef)) {
           shouldRemove = true;
         }
+        isLight &= regionToProcess.getUserData(SIGNATURE) == null;
         FoldingUpdate.RegionInfo regionInfo = infoRef.get();
         matchedInfos.add(regionInfo);
       }
-      if (!shouldRemove && group != null) {
+      if (!shouldRemove && group != null && !isLight) {
         FoldingGroup requestedGroup = null;
         for (FoldingUpdate.RegionInfo matchedInfo : matchedInfos) {
           if (matchedInfo == null) {