upgrade animation

com.unity.uiwidgets/Runtime/animation/animation.cs

             get { return status == AnimationStatus.completed; }
         }
 
+        public Animation<U> drive<U>(Animatable<U> child) {
+            D.assert(this is Animation<float>);
+            return child.animate(this as Animation<float>);
+        }
+
         public override string ToString() {
             return $"{foundation_.describeIdentity(this)}({toStringDetails()})";
         }
 
             D.assert(icon != null);
             return icon;
-        }
-
-        public Animation<U> drive<U>(Animatable<U> child) {
-            D.assert(this is Animation<float>);
-            return child.animate(this as Animation<float>);
         }
     }
 }

com.unity.uiwidgets/Runtime/animation/animation_controller.cs

 using System;
+using System.Collections.Generic;
 using Unity.UIWidgets.foundation;
 using Unity.UIWidgets.physics;
 using Unity.UIWidgets.scheduler2;
         AnimationController(
             float value = 0.0f,
             TimeSpan? duration = null,
+            TimeSpan? reverseDuration = null,
             string debugLabel = null,
             TickerProvider vsync = null
         ) {
             _direction = _AnimationDirection.forward;
 
             this.duration = duration;
+            this.reverseDuration = reverseDuration;
             this.debugLabel = debugLabel;
 
             _ticker = vsync.createTicker(_tick);
         public static AnimationController unbounded(
             float value = 0.0f,
             TimeSpan? duration = null,
+            TimeSpan? reverseDuration = null,
-            return new AnimationController(value, duration, debugLabel, vsync);
+            return new AnimationController(value, duration, reverseDuration, debugLabel, vsync);
         }
 
         public readonly float lowerBound;
             D.assert(() => {
                 if (duration == null) {
                     throw new UIWidgetsError(
-                        "AnimationController.forward() called with no default Duration.\n" +
+                        "AnimationController.forward() called with no default duration.\n" +
                         "The \"duration\" property should be set, either in the constructor or later, before " +
                         "calling the forward() function."
                     );
 
         public TickerFuture reverse(float? from = null) {
             D.assert(() => {
-                if (duration == null) {
+                if (duration == null && reverseDuration == null) {
-                        "AnimationController.reverse() called with no default Duration.\n" +
-                        "The \"duration\" property should be set, either in the constructor or later, before " +
+                        "AnimationController.reverse() called with no default duration or reverseDuration.\n" +
+                        "The \"duration\" or \"reverseDuration\" property should be set, either in the constructor or later, before " +
                         "calling the reverse() function."
                     );
                 }
             TimeSpan? simulationDuration = duration;
             if (simulationDuration == null) {
                 D.assert(() => {
-                    if (this.duration == null) {
+                    if ((this.duration == null && _direction == _AnimationDirection.reverse && reverseDuration == null) || 
+                        (this.duration == null && _direction == _AnimationDirection.forward)) {
-                            "AnimationController.animateTo() called with no explicit Duration and no default Duration.\n" +
+                            "AnimationController.animateTo() called with no explicit Duration and no default duration or reverseDuration.\n" +
-                            "\"duration\" property should be set, either in the constructor or later, before " +
+                            "\"duration\" and/or \"reverseDuration\" property should be set, either in the constructor or later, before " +
                             "calling the animateTo() function."
                         );
                     }
                 float range = upperBound - lowerBound;
                 float remainingFraction = range.isFinite() ? (target - _value).abs() / range : 1.0f;
-                simulationDuration = TimeSpan.FromTicks((long) (this.duration.Value.Ticks * remainingFraction));
+                TimeSpan directionDuration = (_direction == _AnimationDirection.reverse && reverseDuration != null)
+                    ? reverseDuration.Value
+                    : this.duration.Value;
+                
+                simulationDuration = TimeSpan.FromTicks((long) (directionDuration.Ticks * remainingFraction));
             }
             else if (target == value) {
                 simulationDuration = TimeSpan.Zero;
 
             D.assert(max >= min);
             D.assert(max <= upperBound && min >= lowerBound);
-            return animateWith(new _RepeatingSimulation(_value, min.Value, max.Value, reverse, period.Value));
+            stop();
+            return _startSimulation(new _RepeatingSimulation(_value, min.Value, max.Value, reverse, period.Value, _directionSetter));
+        }
+
+        void _directionSetter(_AnimationDirection direction) {
+            _direction = direction;
+            _status = (_direction == _AnimationDirection.forward) ? AnimationStatus.forward : AnimationStatus.reverse;
+            _checkStatusChanged();
         }
 
         public TickerFuture fling(float velocity = 1.0f) {
             Simulation simulation = new SpringSimulation(_kFlingSpringDescription, value,
                 target, velocity);
             simulation.tolerance = _kFlingTolerance;
-            return animateWith(simulation);
+            stop();
+            return _startSimulation(simulation);
         }
 
 
                 "AnimationController methods should not be used after calling dispose."
             );
             stop();
+            _direction = _AnimationDirection.forward;
             return _startSimulation(simulation);
         }
 
         public override void dispose() {
             D.assert(() => {
                 if (_ticker == null) {
-                    throw new UIWidgetsError(
-                        "AnimationController.dispose() called more than once.\n" +
-                        "A given " + GetType() + " cannot be disposed more than once.\n" +
-                        "The following " + GetType() + " object was disposed multiple times:\n" +
-                        "  " + this);
+                    throw new UIWidgetsError(new List<DiagnosticsNode>() {
+                        new ErrorSummary("AnimationController.dispose() called more than once."),
+                        new ErrorDescription($"A given {GetType()} cannot be disposed more than once.\n"),
+                        new DiagnosticsProperty<AnimationController>(
+                            $"The following {GetType()} object was disposed multiple times",
+                            this,
+                            style: DiagnosticsTreeStyle.errorProperty)
+                    });
                 }
 
                 return true;
         }
     }
 
+    delegate void _DirectionSetter(_AnimationDirection direction);
+
-        internal _RepeatingSimulation(float initialValue, float min, float max, bool reverse, TimeSpan period) {
+        internal _RepeatingSimulation(float initialValue, float min, float max, bool reverse, TimeSpan period, _DirectionSetter directionSetter) {
             _min = min;
             _max = max;
             _periodInSeconds = (float) period.Ticks / TimeSpan.TicksPerSecond;
+            this.directionSetter = directionSetter;
             D.assert(_periodInSeconds > 0.0f);
             D.assert(_initialT >= 0.0f);
         }
         readonly float _periodInSeconds;
         readonly bool _reverse;
         readonly float _initialT;
+        readonly _DirectionSetter directionSetter;
 
         public override float x(float timeInSeconds) {
             D.assert(timeInSeconds >= 0.0f);
 
             if (_reverse && _isPlayingReverse) {
+                directionSetter(_AnimationDirection.reverse);
+                directionSetter(_AnimationDirection.forward);
                 return MathUtils.lerpFloat(_min, _max, t);
             }
         }

com.unity.uiwidgets/Runtime/animation/curves.cs

 using System;
+using System.Collections.Generic;
+using System.Linq;
+using Random = System.Random;
-    public abstract class Curve {
-        public float transform(float t) {
-            D.assert(t >= 0.0f && t <= 1.0f);
+    public abstract class ParametricCurve<T> {
+        public virtual T transform(float t) {
+            D.assert(t >= 0.0f && t <= 1.0f, () => $"parametric value {t} is outside of [0, 1] range.");
+            return transformInternal(t);
+        }
+        
+        protected virtual T transformInternal(float t) {
+            throw new NotImplementedException();
+        }
+
+        public override string ToString() {
+            return $"{GetType()}";
+        }
+    }
+    
+    public abstract class Curve : ParametricCurve<float> {
+        public override float transform(float t) {
-            return transformInternal(t);
-        }
-
-        protected virtual float transformInternal(float t) {
-            throw new NotImplementedException();
+            return base.transform(t);
-        }
-
-        public override string ToString() {
-            return GetType().ToString();
         }
     }
 
 
         public override string ToString() {
             return $"{GetType()}({a:F2}, {b:F2}, {c:F2}, {d:F2})";
+        }
+    }
+
+    public abstract class Curve2D : ParametricCurve<Offset> {
+        internal IEnumerable<Curve2DSample> generateSamples(
+            float start = 0.0f,
+            float end = 1.0f,
+            float tolerance = 1e-10f) {
+            D.assert(end > start);
+
+            Random rand = new Random(samplingSeed);
+            bool isFlat(Offset p, Offset q, Offset r) {
+                Offset pr = p - r;
+                Offset qr = q - r;
+                float z = pr.dx * qr.dy - qr.dx * pr.dy;
+                return z * z < tolerance;
+            }
+            
+            Curve2DSample first = new Curve2DSample(start, transform(start));
+            Curve2DSample last = new Curve2DSample(end, transform(end));
+            List<Curve2DSample> samples = new List<Curve2DSample>(){first};
+
+            void sample(Curve2DSample p, Curve2DSample q, bool forceSubdivide = false) {
+                float t = p.t + (0.45f + 0.1f * (float)rand.NextDouble() * (q.t - p.t));
+                Curve2DSample r = new Curve2DSample(t, transform(t));
+
+                if (!forceSubdivide && isFlat(p.value, q.value, r.value)) {
+                    samples.Add(q);
+                }
+                else {
+                    sample(p, r);
+                    sample(r, q);
+                }
+            }
+            
+            sample(first, last,
+                forceSubdivide: (first.value.dx - last.value.dx).abs() < tolerance &&
+                                (first.value.dy - last.value.dy).abs() < tolerance);
+
+            return samples;
+        }
+
+        protected virtual int samplingSeed {
+            get { return 0; }
+        }
+
+        public float findInverse(float x) {
+            float start = 0.0f;
+            float end = 1.0f;
+            float mid = 0f;
+
+            float offsetToOrigin(float pos) {
+                return x - transform(pos).dx;
+            }
+
+            const float errorLimit = 1e-6f;
+            int count = 100;
+            float startValue = offsetToOrigin(start);
+            while ((end - start / 2.0f) > errorLimit && count > 0) {
+                mid = (end + start) / 2.0f;
+                float value = offsetToOrigin(mid);
+                if (value.sign() == startValue.sign()) {
+                    start = mid;
+                }
+                else {
+                    end = mid;
+                }
+
+                count--;
+            }
+
+            return mid;
+        }
+    }
+
+    internal class Curve2DSample {
+        public Curve2DSample(float t, Offset value) {
+            this.t = t;
+            this.value = value;
+        }
+        
+        public readonly float t;
+        public readonly Offset value;
+
+        public override string ToString() {
+            return $"[{value.dx:F2}, {value.dy:F2}, {t:F2}]";
+        }
+    }
+
+    class CatmullRomSpline : Curve2D {
+        CatmullRomSpline(
+            List<Offset> controlPoints,
+            float? tension = 0.0f,
+            Offset startHandle = null,
+            Offset endHandle = null
+        ) {
+            D.assert(controlPoints != null);
+            D.assert(tension != null);
+            D.assert(tension <= 1.0f, () => $"tension {tension} must not be greater than 1.0.");
+            D.assert(tension >= 0.0f, () => $"tension {tension} must not be negative.");
+            D.assert(controlPoints.Count > 3, () => "There must be at least four control points to create a CatmullRomSpline.");
+            _controlPoints = controlPoints;
+            _startHandle = startHandle;
+            _endHandle = endHandle;
+            _tension = tension;
+            _cubicSegments = new List<List<Offset>>();
+        }
+        
+        internal CatmullRomSpline(
+            List<Offset> controlPoints,
+            float? tension = 0.0f,
+            Offset startHandle = null,
+            Offset endHandle = null,
+            List<List<Offset>> cubicSegments = null
+        ) {
+            D.assert(cubicSegments != null);
+            _controlPoints = controlPoints;
+            _startHandle = startHandle;
+            _endHandle = endHandle;
+            _tension = tension;
+            _cubicSegments = new List<List<Offset>>();
+        }
+
+        public static CatmullRomSpline precompute(
+            List<Offset> controlPoints,
+            float? tension = 0.0f,
+            Offset startHandle = null,
+            Offset endHandle = null
+        ) {
+            D.assert(controlPoints != null);
+            D.assert(tension != null);
+            D.assert(tension <= 1.0f, () => $"tension {tension} must not be greater than 1.0.");
+            D.assert(tension >= 0.0f, () => $"tension {tension} must not be negative.");
+            D.assert(controlPoints.Count > 3, () => "There must be at least four control points to create a CatmullRomSpline.");
+            return new CatmullRomSpline(
+                controlPoints: null,
+                tension: null,
+                startHandle: null,
+                endHandle: null,
+                cubicSegments: _computeSegments(controlPoints, tension, startHandle: startHandle, endHandle: endHandle)
+            );
+        }
+
+        static List<List<Offset>> _computeSegments(
+            List<Offset> controlPoints,
+            float? tension,
+            Offset startHandle,
+            Offset endHandle) {
+            startHandle = startHandle ?? controlPoints[0] * 2.0f - controlPoints[1];
+            endHandle = endHandle ?? controlPoints.last() * 2.0f - controlPoints[controlPoints.Count - 2];
+
+            List<Offset> allPoints = new List<Offset>();
+            allPoints.Add(startHandle);
+            allPoints.AddRange(controlPoints);
+            allPoints.Add(endHandle);
+            
+            const float alpha = 0.5f;
+            float reverseTension = 1.0f - tension.Value;
+            List<List<Offset>> result = new List<List<Offset>>();
+            for (int i = 0; i < allPoints.Count - 3; ++i) {
+                List<Offset> curve = new List<Offset>{allPoints[i], allPoints[i + 1], allPoints[i + 2], allPoints[i + 3]};
+                Offset diffCurve10 = curve[1] - curve[0];
+                Offset diffCurve21 = curve[2] - curve[1];
+                Offset diffCurve32 = curve[3] - curve[2];
+                float t01 = Mathf.Pow(diffCurve10.distance, alpha);
+                float t12 = Mathf.Pow(diffCurve21.distance, alpha);
+                float t23 = Mathf.Pow(diffCurve32.distance, alpha);
+                
+                Offset m1 = (diffCurve21 + (diffCurve10 / t01 - (curve[2] - curve[0]) / (t01 + t12)) * t12) * reverseTension;
+                Offset m2 = (diffCurve21 + (diffCurve32 / t23 - (curve[3] - curve[1]) / (t12 + t23)) * t12) * reverseTension;
+                Offset sumM12 = m1 + m2;
+
+                List<Offset> segment = new List<Offset> {
+                    diffCurve21 * -2.0f + sumM12,
+                    diffCurve21 * 3.0f - m1 - sumM12,
+                    m1,
+                    curve[1]
+                };
+                result.Add(segment);
+            }
+
+            return result;
+        }
+
+        readonly List<List<Offset>> _cubicSegments;
+
+        readonly List<Offset> _controlPoints;
+        readonly Offset _startHandle;
+        readonly Offset _endHandle;
+        readonly float? _tension;
+
+        void _initializeIfNeeded() {
+            if (_cubicSegments.isNotEmpty()) {
+                return;
+            }
+            _cubicSegments.AddRange(_computeSegments(_controlPoints, _tension, startHandle: _startHandle, endHandle: _endHandle));
+        }
+
+        protected override int samplingSeed {
+            get {
+                _initializeIfNeeded();
+                Offset seedPoint = _cubicSegments[0][1];
+                return ((seedPoint.dx + seedPoint.dy) * 10000).round();
+            }
+        }
+
+        protected override Offset transformInternal(float t) {
+            _initializeIfNeeded();
+            float length = _cubicSegments.Count;
+            float position;
+            float localT;
+            int index;
+            
+            if (t < 1.0f) {
+                position = t * length;
+                localT = position - position.floor();
+                index = position.floor();
+            } else {
+                position = length;
+                localT = 1.0f;
+                index = _cubicSegments.Count - 1;
+            }
+            List<Offset> cubicControlPoints = _cubicSegments[index];
+            float localT2 = localT * localT;
+            return cubicControlPoints[0] * localT2 * localT
+                   + cubicControlPoints[1] * localT2
+                   + cubicControlPoints[2] * localT
+                   + cubicControlPoints[3];
+        }
+    }
+
+    public class CatmullRomCurve : Curve {
+        public CatmullRomCurve(
+            List<Offset> controlPoints,
+            float? tension = 0.0f) {
+            D.assert(tension != null);
+            
+            this.controlPoints = controlPoints;
+            this.tension = tension;
+            
+            D.assert(() => {
+                _debugAssertReasons.Clear();
+                return validateControlPoints(controlPoints,
+                    tension: tension,
+                    reasons: _debugAssertReasons);
+            }, () => $"control points {controlPoints} could not be validated:\n  {string.Join("\n ", _debugAssertReasons)}");
+            _precomputedSamples = new List<Curve2DSample>();
+        }
+        
+        internal CatmullRomCurve(
+            List<Offset> controlPoints,
+            float? tension = 0.0f,
+            List<Curve2DSample> precomputedSamples = null) {
+            D.assert(precomputedSamples != null);
+            D.assert(tension != null);
+            
+            this.controlPoints = controlPoints;
+            this.tension = tension;
+            
+            D.assert(() => {
+                _debugAssertReasons.Clear();
+                return validateControlPoints(controlPoints,
+                    tension: tension,
+                    reasons: _debugAssertReasons);
+            }, () => $"control points {controlPoints} could not be validated:\n  {string.Join("\n ", _debugAssertReasons)}");
+
+            _precomputedSamples = precomputedSamples;
+        }
+
+        public static CatmullRomCurve precompute(
+            List<Offset> controlPoints, float? tension = 0.0f) {
+            return new CatmullRomCurve(
+                controlPoints,
+                tension,
+                _computeSamples(controlPoints, tension));
+        }
+
+        static List<Curve2DSample> _computeSamples(List<Offset> controlPoints, float? tension) {
+            List<Offset> _controlPoints = new List<Offset>();
+            _controlPoints.Add(Offset.zero);
+            _controlPoints.AddRange(controlPoints);
+            _controlPoints.Add(new Offset(1.0f, 1.0f));
+            
+            return CatmullRomSpline.precompute(_controlPoints, tension: tension).generateSamples(
+                start: 0.0f, end: 1.0f, tolerance: 1e-12f).ToList();
+        }
+        
+        static readonly List<String> _debugAssertReasons = new List<String>();
+
+        readonly List<Curve2DSample> _precomputedSamples;
+
+        public readonly List<Offset> controlPoints;
+
+        public readonly float? tension;
+
+        static bool validateControlPoints(
+            List<Offset> controlPoints,
+            float? tension = 0.0f,
+            List<string> reasons = null) {
+            D.assert(tension != null);
+            if (controlPoints == null) {
+                D.assert(() => {
+                    reasons?.Add("Supplied control points cannot be null");
+                    return true;
+                });
+                return false;
+            }
+
+            if (controlPoints.Count < 2) {
+                D.assert(() => {
+                    reasons?.Add("There must be at least two points supplied to create a valid curve.");
+                    return true;
+                });
+                return false;
+            }
+
+            List<Offset> _controlPoints = new List<Offset>();
+            _controlPoints.AddRange(controlPoints);
+            
+            _controlPoints.Insert(0, Offset.zero);
+            _controlPoints.Add(new Offset(1.0f, 1.0f));
+            
+            Offset startHandle = _controlPoints[0] * 2.0f - _controlPoints[1];
+            Offset endHandle = _controlPoints.last() * 2.0f - _controlPoints[_controlPoints.Count - 2];
+            _controlPoints.Insert(0, startHandle);
+            _controlPoints.Add(endHandle);
+
+            float lastX = -float.PositiveInfinity;
+            for (int i = 0; i < _controlPoints.Count; ++i) {
+                if (i > 1 &&
+                    i < _controlPoints.Count - 2 &&
+                    (_controlPoints[i].dx <= 0.0f || _controlPoints[i].dx >= 1.0f)) {
+                    D.assert(() => {
+                        reasons?.Add("Control points must have X values between 0.0 and 1.0, exclusive. " +
+                        $"Point {i} has an x value ({_controlPoints[i].dx}) which is outside the range.");
+                        return true;
+                    });
+                    return false;
+                }
+                if (_controlPoints[i].dx <= lastX) {
+                    D.assert(() => {
+                        reasons?.Add("Each X coordinate must be greater than the preceding X coordinate " +
+                        $"(i.e. must be monotonically increasing in X). Point {i} has an x value of " + 
+                        $"{_controlPoints[i].dx}, which is not greater than {lastX}");
+                        return true;
+                    });
+                    return false;
+                }
+                lastX = _controlPoints[i].dx;
+            }
+            
+            bool success = true;
+            lastX = -float.PositiveInfinity;
+            const float tolerance = 1e-3f;
+            CatmullRomSpline testSpline = new CatmullRomSpline(_controlPoints, tension: tension);
+            float start = testSpline.findInverse(0.0f);
+            float end = testSpline.findInverse(1.0f);
+            IEnumerable<Curve2DSample> samplePoints = testSpline.generateSamples(start: start, end: end);
+
+            if (samplePoints.First().value.dy.abs() > tolerance ||
+                (1.0f - samplePoints.Last().value.dy).abs() > tolerance) {
+                bool bail = true;
+                success = false;
+                D.assert(() => {
+                    reasons?.Add($"The curve has more than one Y value at X = {samplePoints.First().value.dx}. " +
+                    "Try moving some control points further away from this value of X, or increasing " + 
+                    "the tension.");
+                    bail = reasons == null;
+                    return true;
+                });
+                if (bail) {
+                    return false;
+                }
+            }
+            foreach (Curve2DSample sample in samplePoints) {
+                Offset point = sample.value;
+                float t = sample.t;
+                float x = point.dx;
+                if (t >= start && t <= end && (x < -1e-3f || x > 1.0f + 1e-3f)) {
+                    bool bail = true;
+                    success = false;
+                    D.assert(() => {
+                        reasons?.Add($"The resulting curve has an X value ({x}) which is outside " +
+                        "the range [0.0, 1.0], inclusive.");
+                        bail = reasons == null;
+                        return true;
+                    });
+                    if (bail) {
+                        return false;
+                    }
+                }
+                if (x < lastX) {
+                    bool bail = true;
+                    success = false;
+                    D.assert(() => {
+                        reasons?.Add($"The curve has more than one Y value at x = {x}. Try moving " +
+                        "some control points further apart in X, or increasing the tension.");
+                        bail = reasons == null;
+                        return true;
+                    });
+                    if (bail) {
+                        return false;
+                    }
+                }
+                lastX = x;
+            }
+            return success;
+        }
+
+        protected override float transformInternal(float t) {
+            if (_precomputedSamples.isEmpty()) {
+                // Compute the samples now if we were constructed lazily.
+                _precomputedSamples.AddRange(_computeSamples(controlPoints, tension));
+            }
+            int start = 0;
+            int end = _precomputedSamples.Count - 1;
+            int mid;
+            Offset value;
+            Offset startValue = _precomputedSamples[start].value;
+            Offset endValue = _precomputedSamples[end].value;
+            while (end - start > 1) {
+                mid = (end + start) / 2;
+                value = _precomputedSamples[mid].value;
+                if (t >= value.dx) {
+                    start = mid;
+                    startValue = value;
+                } else {
+                    end = mid;
+                    endValue = value;
+                }
+            }
+            float t2 = (t - startValue.dx) / (endValue.dx - startValue.dx);
+            return Mathf.Lerp(startValue.dy, endValue.dy, t2);
         }
     }
 

com.unity.uiwidgets/Runtime/animation/listener_helpers.mixin.gen.cs

 using Unity.UIWidgets.ui;
 
 namespace Unity.UIWidgets.animation {
+
+ 
-        int _listenerCounter = 0;
+        int _listenerCounter;
 
         protected void didRegisterListener() {
             D.assert(_listenerCounter >= 0);
     }
 
 
+
+ 
     public abstract class AnimationEagerListenerMixinAnimation<T> : Animation<T> {
         protected void didRegisterListener() {
         }
     }
 
 
-    public abstract class
-        AnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T> : AnimationLazyListenerMixinAnimation<T> {
+
+ 
+    public abstract class AnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T> : AnimationLazyListenerMixinAnimation<T> {
         readonly ObserverList<VoidCallback> _listeners = new ObserverList<VoidCallback>();
 
         public override void addListener(VoidCallback listener) {
         public void notifyListeners() {
             var localListeners = new List<VoidCallback>(_listeners);
             foreach (VoidCallback listener in localListeners) {
+                InformationCollector collector = null;
+                D.assert(() => {
+                      IEnumerable<DiagnosticsNode> infoCollector() {
+                          yield return new DiagnosticsProperty<AnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T>>(
+                              "The " + GetType() + " notifying listeners was:",
+                              this,
+                              style: DiagnosticsTreeStyle.errorProperty
+                          );
+                      }
+                      collector = infoCollector;
+                      return true;
+                });
-                }
-                catch (Exception exception) {
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<
-                            AnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T>>(
-                            "The " + GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
-
+                } catch (Exception exception) {
-                        informationCollector: infoCollector
+                        informationCollector: collector
                     ));
                 }
             }
 
-    public abstract class
-        AnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T> : AnimationEagerListenerMixinAnimation<T> {
+ 
+    public abstract class AnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T> : AnimationEagerListenerMixinAnimation<T> {
         readonly ObserverList<VoidCallback> _listeners = new ObserverList<VoidCallback>();
 
         public override void addListener(VoidCallback listener) {
         public void notifyListeners() {
             var localListeners = new List<VoidCallback>(_listeners);
             foreach (VoidCallback listener in localListeners) {
+                InformationCollector collector = null;
+                D.assert(() => {
+                      IEnumerable<DiagnosticsNode> infoCollector() {
+                          yield return new DiagnosticsProperty<AnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T>>(
+                              "The " + GetType() + " notifying listeners was:",
+                              this,
+                              style: DiagnosticsTreeStyle.errorProperty
+                          );
+                      }
+                      collector = infoCollector;
+                      return true;
+                });
-                }
-                catch (Exception exception) {
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<
-                            AnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T>>(
-                            "The " + GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
-
+                } catch (Exception exception) {
-                        informationCollector: infoCollector
+                        informationCollector: collector
                     ));
                 }
             }
 
-    public abstract class
-        AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T> :
-            AnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T> {
+
+ 
+    public abstract class AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T> : AnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T> {
         readonly ObserverList<AnimationStatusListener> _statusListeners = new ObserverList<AnimationStatusListener>();
 
         public override void addStatusListener(AnimationStatusListener listener) {
                     if (_statusListeners.Contains(listener)) {
                         listener(status);
                     }
-                }
-                catch (Exception exception) {
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<
-                            AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationLazyListenerMixinAnimation
-                            <T>>(
-                            "The " + GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
-
+                } catch (Exception exception) {
+                    InformationCollector collector = null;
+                    D.assert(() => {
+                        IEnumerable<DiagnosticsNode> infoCollector() {
+                            yield return new DiagnosticsProperty<AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationLazyListenerMixinAnimation<T>>(
+                                "The " + GetType() + " notifying status listeners was:",
+                                this,
+                                style: DiagnosticsTreeStyle.errorProperty
+                            );
+                        }
+                        
+                        collector = infoCollector;
+                        return true;
+                    });
+                
-                        informationCollector: infoCollector
+                        informationCollector: collector
                     ));
                 }
             }
 
-    public abstract class
-        AnimationLocalStatusListenersMixinAnimationLazyListenerMixinAnimation<T> : AnimationLazyListenerMixinAnimation<T
-        > {
+ 
+    public abstract class AnimationLocalStatusListenersMixinAnimationLazyListenerMixinAnimation<T> : AnimationLazyListenerMixinAnimation<T> {
         readonly ObserverList<AnimationStatusListener> _statusListeners = new ObserverList<AnimationStatusListener>();
 
         public override void addStatusListener(AnimationStatusListener listener) {
                     if (_statusListeners.Contains(listener)) {
                         listener(status);
                     }
-                }
-                catch (Exception exception) {
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<
-                            AnimationLocalStatusListenersMixinAnimationLazyListenerMixinAnimation<T>>(
-                            "The " + GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
-
+                } catch (Exception exception) {
+                    InformationCollector collector = null;
+                    D.assert(() => {
+                        IEnumerable<DiagnosticsNode> infoCollector() {
+                            yield return new DiagnosticsProperty<AnimationLocalStatusListenersMixinAnimationLazyListenerMixinAnimation<T>>(
+                                "The " + GetType() + " notifying status listeners was:",
+                                this,
+                                style: DiagnosticsTreeStyle.errorProperty
+                            );
+                        }
+                        
+                        collector = infoCollector;
+                        return true;
+                    });
+                
-                        informationCollector: infoCollector
+                        informationCollector: collector
                     ));
                 }
             }
 
-    public abstract class
-        AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T> :
-            AnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T> {
+ 
+    public abstract class AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T> : AnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T> {
         readonly ObserverList<AnimationStatusListener> _statusListeners = new ObserverList<AnimationStatusListener>();
 
         public override void addStatusListener(AnimationStatusListener listener) {
                     if (_statusListeners.Contains(listener)) {
                         listener(status);
                     }
-                }
-                catch (Exception exception) {
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<
-                            AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationEagerListenerMixinAnimation
-                            <T>>(
-                            "The " + GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
-
+                } catch (Exception exception) {
+                    InformationCollector collector = null;
+                    D.assert(() => {
+                        IEnumerable<DiagnosticsNode> infoCollector() {
+                            yield return new DiagnosticsProperty<AnimationLocalStatusListenersMixinAnimationLocalListenersMixinAnimationEagerListenerMixinAnimation<T>>(
+                                "The " + GetType() + " notifying status listeners was:",
+                                this,
+                                style: DiagnosticsTreeStyle.errorProperty
+                            );
+                        }
+                        
+                        collector = infoCollector;
+                        return true;
+                    });
+                
-                        informationCollector: infoCollector
+                        informationCollector: collector
+
+
 }

com.unity.uiwidgets/Runtime/animation/listener_helpers.mixin.njk

         public void notifyListeners() {
             var localListeners = new List<VoidCallback>(this._listeners);
             foreach (VoidCallback listener in localListeners) {
+                InformationCollector collector = null;
+                D.assert(() => {
+                      IEnumerable<DiagnosticsNode> infoCollector() {
+                          yield return new DiagnosticsProperty<AnimationLocalListenersMixin{{with | safe}}>(
+                              "The " + this.GetType() + " notifying listeners was:",
+                              this,
+                              style: DiagnosticsTreeStyle.errorProperty
+                          );
+                      }
+                      collector = infoCollector;
+                      return true;
+                });
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<AnimationLocalListenersMixin{{with | safe}}>(
-                            "The " + this.GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
-                    
-                        informationCollector: infoCollector
+                        informationCollector: collector
                     ));
                 }
             }
                         listener(status);
                     }
                 } catch (Exception exception) {
-                    IEnumerable<DiagnosticsNode> infoCollector() {
-                        yield return new DiagnosticsProperty<AnimationLocalStatusListenersMixin{{with | safe}}>(
-                            "The " + this.GetType() + " notifying listeners was:",
-                            this,
-                            style: DiagnosticsTreeStyle.errorProperty
-                        );
-                    }
+                    InformationCollector collector = null;
+                    D.assert(() => {
+                        IEnumerable<DiagnosticsNode> infoCollector() {
+                            yield return new DiagnosticsProperty<AnimationLocalStatusListenersMixin{{with | safe}}>(
+                                "The " + this.GetType() + " notifying status listeners was:",
+                                this,
+                                style: DiagnosticsTreeStyle.errorProperty
+                            );
+                        }
+                        
+                        collector = infoCollector;
+                        return true;
+                    });
-                        informationCollector: infoCollector
+                        informationCollector: collector
                     ));
                 }
             }

com.unity.uiwidgets/Runtime/animation/tween.cs

             return lerp(t);
         }
 
-
-        /*public override T evaluate(Animation<float> animation) {
-            float t = animation.value;
-            if (t == 0.0) {
-                return begin;
-            }
-
-            if (t == 1.0) {
-                return end;
-            }
-
-            return lerp(t);
-        }*/
-
         public override string ToString() {
             return $"{GetType()}({begin} \u2192 {end})";
         }

com.unity.uiwidgets/Runtime/animation/tween_sequence.cs

               if (_intervals[index].contains(t))
                 return _evaluateAt(t, index);
             }
-            D.assert(false, ()=>"TweenSequence.evaluate() could not find an interval for $t");
+            D.assert(false, ()=> $"TweenSequence.evaluate() could not find an interval for {t}");
             return default(T);
         }
         public override string ToString(){