<!-- NEW5 — TEST 5 · THE BEND AT THE HEART · part 278 -->
nsForClip && actionsForClip.knownActions[ 0 ] );

				this._addInactiveAction( action, clipUuid, rootUuid );

			}

			const bindings = action._propertyBindings;

			// increment reference counts / sort out state
			for ( let i = 0, n = bindings.length; i !== n; ++ i ) {

				const binding = bindings[ i ];

				if ( binding.useCount ++ === 0 ) {

					this._lendBinding( binding );
					binding.saveOriginalState();

				}

			}

			this._lendAction( action );

		}

	}

	_deactivateAction( action ) {

		if ( this._isActiveAction( action ) ) {

			const bindings = action._propertyBindings;

			// decrement reference counts / sort out state
			for ( let i = 0, n = bindings.length; i !== n; ++ i ) {

				const binding = bindings[ i ];

				if ( -- binding.useCount === 0 ) {

					binding.restoreOriginalState();
					this._takeBackBinding( binding );

				}

			}

			this._takeBackAction( action );

		}

	}

	// Memory manager

	_initMemoryManager() {

		this._actions = []; // 'nActiveActions' followed by inactive ones
		this._nActiveActions = 0;

		this._actionsByClip = {};
		// inside:
		// {
		// 	knownActions: Array< AnimationAction > - used as prototypes
		// 	actionByRoot: AnimationAction - lookup
		// }


		this._bindings = []; // 'nActiveBindings' followed by inactive ones
		this._nActiveBindings = 0;

		this._bindingsByRootAndName = {}; // inside: Map< name, PropertyMixer >


		this._controlInterpolants = []; // same game as above
		this._nActiveControlInterpolants = 0;

		const scope = this;

		this.stats = {

			actions: {
				get total() {

					return scope._actions.length;

				},
				get inUse() {

					return scope._nActiveActions;

				}
			},
			bindings: {
				get total() {

					return scope._bindings.length;

				},
				get inUse() {

					return scope._nActiveBindings;

				}
			},
			controlInterpolants: {
				get total() {

					return scope._controlInterpolants.length;

				},
				get inUse() {

					return scope._nActiveControlInterpolants;

				}
			}

		};

	}

	// Memory management for AnimationAction objects

	_isActiveAction( action ) {

		const index = action._cacheIndex;
		return index !== null && index < this._nActiveActions;

	}

	_addInactiveAction( action, clipUuid, rootUuid ) {

		const actions = this._actions,
			actionsByClip = this._actionsByClip;

		let actionsForClip = actionsByClip[ clipUuid ];

		if ( actionsForClip === undefined ) {

			actionsForClip = {

				knownActions: [ action ],
				actionByRoot: {}

			};

			action._byClipCacheIndex = 0;

			actionsByClip[ clipUuid ] = actionsForClip;

		} else {

			const knownActions = actionsForClip.knownActions;

			action._byClipCacheIndex = knownActions.length;
			knownActions.push( action );

		}

		action._cacheIndex = actions.length;
		actions.push( action );

		actionsForClip.actionByRoot[ rootUuid ] = action;

	}

	_removeInactiveAction( action ) {

		const actions = this._actions,
			lastInactiveAction = actions[ actions.length - 1 ],
			cacheIndex = action._cacheIndex;

		lastInactiveAction._cacheIndex = cacheIndex;
		actions[ cacheIndex ] = lastInactiveAction;
		actions.pop();

		action._cacheIndex = null;


		const clipUuid = action._clip.uuid,
			actionsByClip = this._actionsByClip,
			actionsForClip = actionsByClip[ clipUuid ],
			knownActionsForClip = actionsForClip.knownActions,

			lastKnownAction =
				knownActionsForClip[ knownActionsForClip.length - 1 ],

			byClipCacheIndex = action._byClipCacheIndex;

		lastKnownAction._byClipCacheIndex = byClipCacheIndex;
		knownActionsForClip[ byClipCacheIndex ] = lastKnownAction;
		knownActionsForClip.pop();

		action._byClipCacheIndex = null;


		const actionByRoot = actionsForClip.actionByRoot,
			rootUuid = ( action._localRoot || this._root ).uuid;

		delete actionByRoot[ rootUuid ];

		if ( knownActionsForClip.length === 0 ) {

			delete actionsByClip[ clipUuid ];

		}

		this._removeInactiveBindingsForAction( action );

	}

	_removeInactiveBindingsForAction( action ) {

		const bindings = action._propertyBindings;

		for ( let i = 0, n = bindings.length; i !== n; ++ i ) {

			const binding = bindings[ i ];

			if ( -- binding.referenceCount === 0 ) {

				this._removeInactiveBinding( binding );

			}

		}

	}

	_lendAction( action ) {

		// [ active actions |  inactive actions  ]
		// [  active actions >| inactive actions ]
		//                 s        a
		//                  <-swap->
		//                 a        s

		const actions = this._actions,
			prevIndex = action._cacheIndex,

			lastActiveIndex = this._nActiveActions ++,

			firstInactiveAction = actions[ lastActiveIndex ];

		action._cacheIndex = lastActiveIndex;
		actions[ lastActiveIndex ] = action;

		firstInactiveAction._cacheIndex = prevIndex;
		actions[ prevIndex ] = firstInactiveAction;

	}

	_takeBackAction( action ) {

		// [  active actions  | inactive actions ]
		// [ active actions |< inactive actions  ]
		//        a        s