Add API to disable history tracking in EditSessions (#2189)

* Add API to disable history tracking in EditSessions

* Update worldedit-core/src/main/java/com/sk89q/worldedit/extent/ChangeSetExtent.java

Co-authored-by: Octavia Togami <octavia.togami@gmail.com>

Co-authored-by: Octavia Togami <octavia.togami@gmail.com>

worldedit-core/src/main/java/com/sk89q/worldedit/EditSession.java

@@ -207,6 +207,7 @@ public String getDisplayName() {
     private final MultiStageReorder reorderExtent;
     private final MaskingExtent maskingExtent;
     private final BlockChangeLimiter changeLimiter;
+    private @Nullable ChangeSetExtent changeSetExtent;
     private final List<WatchdogTickingExtent> watchdogExtents = new ArrayList<>(2);
 
     private final Extent bypassReorderHistory;
@@ -284,7 +285,7 @@ public String getDisplayName() {
             this.bypassHistory = traceIfNeeded(new DataValidatorExtent(extent, world));
 
             // These extents can be skipped by calling smartSetBlock()
-            extent = traceIfNeeded(new ChangeSetExtent(extent, changeSet));
+            extent = traceIfNeeded(changeSetExtent = new ChangeSetExtent(extent, changeSet));
             extent = traceIfNeeded(maskingExtent = new MaskingExtent(extent, Masks.alwaysTrue()));
             extent = traceIfNeeded(changeLimiter = new BlockChangeLimiter(extent, maxBlocks));
             extent = wrapExtent(extent, eventBus, event, Stage.BEFORE_HISTORY);
@@ -864,6 +865,28 @@ public void redo(EditSession editSession) {
         editSession.internalFlushSession();
     }
 
+    /**
+     * Gets whether this EditSession will track history.
+     *
+     * @return whether history is tracked
+     */
+    public boolean isTrackingHistory() {
+        return changeSetExtent != null && changeSetExtent.isEnabled();
+    }
+
+    /**
+     * Sets whether this EditSession will track history.
+     *
+     * @param trackHistory whether to track history
+     */
+    public void setTrackingHistory(boolean trackHistory) {
+        if (changeSetExtent != null) {
+            changeSetExtent.setEnabled(trackHistory);
+        } else if (trackHistory) {
+            throw new IllegalStateException("No ChangeSetExtent is available");
+        }
+    }
+
     /**
      * Get the number of changed blocks.
      *

worldedit-core/src/main/java/com/sk89q/worldedit/extent/ChangeSetExtent.java

@@ -46,6 +46,7 @@
 public class ChangeSetExtent extends AbstractDelegateExtent {
 
     private final ChangeSet changeSet;
+    private boolean enabled;
 
     /**
      * Create a new instance.
@@ -54,22 +55,56 @@ public class ChangeSetExtent extends AbstractDelegateExtent {
      * @param changeSet the change set
      */
     public ChangeSetExtent(Extent extent, ChangeSet changeSet) {
+        this(extent, changeSet, true);
+    }
+
+    /**
+     * Create a new instance.
+     *
+     * @param extent the extent
+     * @param changeSet the change set
+     * @param enabled if the extent is enabled
+     */
+    public ChangeSetExtent(Extent extent, ChangeSet changeSet, boolean enabled) {
         super(extent);
         checkNotNull(changeSet);
         this.changeSet = changeSet;
+        this.enabled = true;
+    }
+
+    /**
+     * If this extent is enabled and should perform change tracking.
+     *
+     * @return if enabled
+     */
+    public boolean isEnabled() {
+        return this.enabled;
+    }
+
+    /**
+     * Sets whether this extent is enabled and should perform change tracking.
+     *
+     * @param enabled whether to enable
+     */
+    public void setEnabled(boolean enabled) {
+        this.enabled = enabled;
     }
 
     @Override
     public <B extends BlockStateHolder<B>> boolean setBlock(BlockVector3 location, B block) throws WorldEditException {
-        BaseBlock previous = getFullBlock(location);
-        changeSet.add(new BlockChange(location, previous, block));
+        if (enabled) {
+            BaseBlock previous = getFullBlock(location);
+            changeSet.add(new BlockChange(location, previous, block));
+        }
         return super.setBlock(location, block);
     }
 
     @Override
     public boolean setBiome(BlockVector3 position, BiomeType biome) {
-        BiomeType previous = getBiome(position);
-        changeSet.add(new BiomeChange3D(position, previous, biome));
+        if (enabled) {
+            BiomeType previous = getBiome(position);
+            changeSet.add(new BiomeChange3D(position, previous, biome));
+        }
         return super.setBiome(position, biome);
     }
 
@@ -77,7 +112,7 @@ public boolean setBiome(BlockVector3 position, BiomeType biome) {
     @Override
     public Entity createEntity(Location location, BaseEntity state) {
         Entity entity = super.createEntity(location, state);
-        if (entity != null) {
+        if (enabled && entity != null) {
             changeSet.add(new EntityCreate(location, state, entity));
         }
         return entity;
@@ -94,6 +129,9 @@ public List<? extends Entity> getEntities(Region region) {
     }
 
     private List<? extends Entity> wrapEntities(List<? extends Entity> entities) {
+        if (!enabled) {
+            return entities;
+        }
         List<Entity> newList = new ArrayList<>(entities.size());
         for (Entity entity : entities) {
             newList.add(new TrackedEntity(entity));