Add unary operator (#3604)

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## Fixes #
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Fixes #3523 

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Introduce UnaryOperator to animation expressions, a new type of operation that only expects one operator, to fix the issue where the ! operator failed because it expected 2 operators like the other (non-unary) operators.

## PR Type
What kind of change does this PR introduce?
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Bugfix 
<!-- - Feature -->
<!-- - Code style update (formatting) -->
<!-- - Refactoring (no functional changes, no api changes) -->
<!-- - Build or CI related changes -->
<!-- - Documentation content changes -->
<!-- - Sample app changes -->
<!-- - Other... Please describe: -->


## What is the current behavior?
With the current version of the toolkit, code like
```
    var visual = Windows.UI.Xaml.Hosting.ElementCompositionPreview.GetElementVisual(this);
    var a = !(visual.GetReference().Offset.X > 10);
    visual.StartAnimation("Offset.Y", ExpressionFunctions.Conditional(a, 1,2));
```
will throw this exception
`Can't have an operator that doesn't have 2 exactly params`

## What is the new behavior?
After these changes, no exception is thrown and the correct animation expression is generated

## PR Checklist

Please check if your PR fulfills the following requirements:

- [X] Tested code with current [supported SDKs](../readme.md#supported)
- [ ] Pull Request has been submitted to the documentation repository [instructions](..\contributing.md#docs). Link: <!-- docs PR link -->
- [ ] Sample in sample app has been added / updated (for bug fixes / features)
    - [ ] Icon has been created (if new sample) following the [Thumbnail Style Guide and templates](https://github.com/windows-toolkit/WindowsCommunityToolkit-design-assets)
- [ ] Tests for the changes have been added (for bug fixes / features) (if applicable)
- [ ] Header has been added to all new source files (run *build/UpdateHeaders.bat*)
- [X] Contains **NO** breaking changes

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     Please note that breaking changes are likely to be rejected within minor release cycles or held until major versions. -->


## Other information

Author: msftbot[bot]

Microsoft.Toolkit.Uwp.UI.Animations/Expressions/ExpressionFunctions.cs

@@ -1253,80 +1253,80 @@ public ExpressionNodeInfo(OperationType nodeOperationKind, string operationStrin
         /// </summary>
         private static readonly Dictionary<ExpressionNodeType, ExpressionNodeInfo> _expressionNodeInfo = new Dictionary<ExpressionNodeType, ExpressionNodeInfo>
         {
-            { ExpressionNodeType.ConstantValue,            new ExpressionNodeInfo(OperationType.Constant,    null) },
-            { ExpressionNodeType.ConstantParameter,        new ExpressionNodeInfo(OperationType.Constant,    null) },
-            { ExpressionNodeType.CurrentValueProperty,     new ExpressionNodeInfo(OperationType.Reference,   null) },
-            { ExpressionNodeType.Reference,                new ExpressionNodeInfo(OperationType.Reference,   null) },
-            { ExpressionNodeType.ReferenceProperty,        new ExpressionNodeInfo(OperationType.Reference,   null) },
-            { ExpressionNodeType.StartingValueProperty,    new ExpressionNodeInfo(OperationType.Reference,   null) },
-            { ExpressionNodeType.TargetReference,          new ExpressionNodeInfo(OperationType.Reference,   null) },
-            { ExpressionNodeType.Conditional,              new ExpressionNodeInfo(OperationType.Conditional, null) },
-            { ExpressionNodeType.Swizzle,                  new ExpressionNodeInfo(OperationType.Swizzle,     null) },
-            { ExpressionNodeType.Add,                      new ExpressionNodeInfo(OperationType.Operator,    "+") },
-            { ExpressionNodeType.And,                      new ExpressionNodeInfo(OperationType.Operator,    "&&") },
-            { ExpressionNodeType.Divide,                   new ExpressionNodeInfo(OperationType.Operator,    "/") },
-            { ExpressionNodeType.Equals,                   new ExpressionNodeInfo(OperationType.Operator,    "==") },
-            { ExpressionNodeType.GreaterThan,              new ExpressionNodeInfo(OperationType.Operator,    ">") },
-            { ExpressionNodeType.GreaterThanEquals,        new ExpressionNodeInfo(OperationType.Operator,    ">=") },
-            { ExpressionNodeType.LessThan,                 new ExpressionNodeInfo(OperationType.Operator,    "<") },
-            { ExpressionNodeType.LessThanEquals,           new ExpressionNodeInfo(OperationType.Operator,    "<=") },
-            { ExpressionNodeType.Multiply,                 new ExpressionNodeInfo(OperationType.Operator,    "*") },
-            { ExpressionNodeType.Not,                      new ExpressionNodeInfo(OperationType.Operator,    "!") },
-            { ExpressionNodeType.NotEquals,                new ExpressionNodeInfo(OperationType.Operator,    "!=") },
-            { ExpressionNodeType.Or,                       new ExpressionNodeInfo(OperationType.Operator,    "||") },
-            { ExpressionNodeType.Subtract,                 new ExpressionNodeInfo(OperationType.Operator,    "-") },
-            { ExpressionNodeType.Absolute,                 new ExpressionNodeInfo(OperationType.Function,    "abs") },
-            { ExpressionNodeType.Acos,                     new ExpressionNodeInfo(OperationType.Function,    "acos") },
-            { ExpressionNodeType.Asin,                     new ExpressionNodeInfo(OperationType.Function,    "asin") },
-            { ExpressionNodeType.Atan,                     new ExpressionNodeInfo(OperationType.Function,    "atan") },
-            { ExpressionNodeType.Cos,                      new ExpressionNodeInfo(OperationType.Function,    "cos") },
-            { ExpressionNodeType.Ceil,                     new ExpressionNodeInfo(OperationType.Function,    "ceil") },
-            { ExpressionNodeType.Clamp,                    new ExpressionNodeInfo(OperationType.Function,    "clamp") },
-            { ExpressionNodeType.ColorHsl,                 new ExpressionNodeInfo(OperationType.Function,    "colorhsl") },
-            { ExpressionNodeType.ColorRgb,                 new ExpressionNodeInfo(OperationType.Function,    "colorrgb") },
-            { ExpressionNodeType.ColorLerp,                new ExpressionNodeInfo(OperationType.Function,    "colorlerp") },
-            { ExpressionNodeType.ColorLerpHsl,             new ExpressionNodeInfo(OperationType.Function,    "colorhsllerp") },
-            { ExpressionNodeType.ColorLerpRgb,             new ExpressionNodeInfo(OperationType.Function,    "colorrgblerp") },
-            { ExpressionNodeType.Concatenate,              new ExpressionNodeInfo(OperationType.Function,    "concatenate") },
-            { ExpressionNodeType.Distance,                 new ExpressionNodeInfo(OperationType.Function,    "distance") },
-            { ExpressionNodeType.DistanceSquared,          new ExpressionNodeInfo(OperationType.Function,    "distancesquared") },
-            { ExpressionNodeType.Floor,                    new ExpressionNodeInfo(OperationType.Function,    "floor") },
-            { ExpressionNodeType.Inverse,                  new ExpressionNodeInfo(OperationType.Function,    "inverse") },
-            { ExpressionNodeType.Length,                   new ExpressionNodeInfo(OperationType.Function,    "length") },
-            { ExpressionNodeType.LengthSquared,            new ExpressionNodeInfo(OperationType.Function,    "lengthsquared") },
-            { ExpressionNodeType.Lerp,                     new ExpressionNodeInfo(OperationType.Function,    "lerp") },
-            { ExpressionNodeType.Ln,                       new ExpressionNodeInfo(OperationType.Function,    "ln") },
-            { ExpressionNodeType.Log10,                    new ExpressionNodeInfo(OperationType.Function,    "log10") },
-            { ExpressionNodeType.Max,                      new ExpressionNodeInfo(OperationType.Function,    "max") },
-            { ExpressionNodeType.Matrix3x2FromRotation,    new ExpressionNodeInfo(OperationType.Function,    "matrix3x2.createrotation") },
-            { ExpressionNodeType.Matrix3x2FromScale,       new ExpressionNodeInfo(OperationType.Function,    "matrix3x2.createscale") },
-            { ExpressionNodeType.Matrix3x2FromSkew,        new ExpressionNodeInfo(OperationType.Function,    "matrix3x2.createskew") },
-            { ExpressionNodeType.Matrix3x2FromTranslation, new ExpressionNodeInfo(OperationType.Function,    "matrix3x2.createtranslation") },
-            { ExpressionNodeType.Matrix3x2,                new ExpressionNodeInfo(OperationType.Function,    "matrix3x2") },
-            { ExpressionNodeType.Matrix4x4FromAxisAngle,   new ExpressionNodeInfo(OperationType.Function,    "matrix4x4.createfromaxisangle") },
-            { ExpressionNodeType.Matrix4x4FromScale,       new ExpressionNodeInfo(OperationType.Function,    "matrix4x4.createscale") },
-            { ExpressionNodeType.Matrix4x4FromTranslation, new ExpressionNodeInfo(OperationType.Function,    "matrix4x4.createtranslation") },
-            { ExpressionNodeType.Matrix4x4,                new ExpressionNodeInfo(OperationType.Function,    "matrix4x4") },
-            { ExpressionNodeType.Min,                      new ExpressionNodeInfo(OperationType.Function,    "min") },
-            { ExpressionNodeType.Modulus,                  new ExpressionNodeInfo(OperationType.Function,    "mod") },
-            { ExpressionNodeType.Negate,                   new ExpressionNodeInfo(OperationType.Function,    "-") },
-            { ExpressionNodeType.Normalize,                new ExpressionNodeInfo(OperationType.Function,    "normalize") },
-            { ExpressionNodeType.Pow,                      new ExpressionNodeInfo(OperationType.Function,    "pow") },
-            { ExpressionNodeType.QuaternionFromAxisAngle,  new ExpressionNodeInfo(OperationType.Function,    "quaternion.createfromaxisangle") },
-            { ExpressionNodeType.Quaternion,               new ExpressionNodeInfo(OperationType.Function,    "quaternion") },
-            { ExpressionNodeType.Round,                    new ExpressionNodeInfo(OperationType.Function,    "round") },
-            { ExpressionNodeType.Scale,                    new ExpressionNodeInfo(OperationType.Function,    "scale") },
-            { ExpressionNodeType.Sin,                      new ExpressionNodeInfo(OperationType.Function,    "sin") },
-            { ExpressionNodeType.Slerp,                    new ExpressionNodeInfo(OperationType.Function,    "slerp") },
-            { ExpressionNodeType.Sqrt,                     new ExpressionNodeInfo(OperationType.Function,    "sqrt") },
-            { ExpressionNodeType.Square,                   new ExpressionNodeInfo(OperationType.Function,    "square") },
-            { ExpressionNodeType.Tan,                      new ExpressionNodeInfo(OperationType.Function,    "tan") },
-            { ExpressionNodeType.ToDegrees,                new ExpressionNodeInfo(OperationType.Function,    "todegrees") },
-            { ExpressionNodeType.ToRadians,                new ExpressionNodeInfo(OperationType.Function,    "toradians") },
-            { ExpressionNodeType.Transform,                new ExpressionNodeInfo(OperationType.Function,    "transform") },
-            { ExpressionNodeType.Vector2,                  new ExpressionNodeInfo(OperationType.Function,    "vector2") },
-            { ExpressionNodeType.Vector3,                  new ExpressionNodeInfo(OperationType.Function,    "vector3") },
-            { ExpressionNodeType.Vector4,                  new ExpressionNodeInfo(OperationType.Function,    "vector4") },
+            { ExpressionNodeType.ConstantValue,            new ExpressionNodeInfo(OperationType.Constant,      null) },
+            { ExpressionNodeType.ConstantParameter,        new ExpressionNodeInfo(OperationType.Constant,      null) },
+            { ExpressionNodeType.CurrentValueProperty,     new ExpressionNodeInfo(OperationType.Reference,     null) },
+            { ExpressionNodeType.Reference,                new ExpressionNodeInfo(OperationType.Reference,     null) },
+            { ExpressionNodeType.ReferenceProperty,        new ExpressionNodeInfo(OperationType.Reference,     null) },
+            { ExpressionNodeType.StartingValueProperty,    new ExpressionNodeInfo(OperationType.Reference,     null) },
+            { ExpressionNodeType.TargetReference,          new ExpressionNodeInfo(OperationType.Reference,     null) },
+            { ExpressionNodeType.Conditional,              new ExpressionNodeInfo(OperationType.Conditional,   null) },
+            { ExpressionNodeType.Swizzle,                  new ExpressionNodeInfo(OperationType.Swizzle,       null) },
+            { ExpressionNodeType.Add,                      new ExpressionNodeInfo(OperationType.Operator,      "+") },
+            { ExpressionNodeType.And,                      new ExpressionNodeInfo(OperationType.Operator,      "&&") },
+            { ExpressionNodeType.Divide,                   new ExpressionNodeInfo(OperationType.Operator,      "/") },
+            { ExpressionNodeType.Equals,                   new ExpressionNodeInfo(OperationType.Operator,      "==") },
+            { ExpressionNodeType.GreaterThan,              new ExpressionNodeInfo(OperationType.Operator,      ">") },
+            { ExpressionNodeType.GreaterThanEquals,        new ExpressionNodeInfo(OperationType.Operator,      ">=") },
+            { ExpressionNodeType.LessThan,                 new ExpressionNodeInfo(OperationType.Operator,      "<") },
+            { ExpressionNodeType.LessThanEquals,           new ExpressionNodeInfo(OperationType.Operator,      "<=") },
+            { ExpressionNodeType.Multiply,                 new ExpressionNodeInfo(OperationType.Operator,      "*") },
+            { ExpressionNodeType.Not,                      new ExpressionNodeInfo(OperationType.UnaryOperator, "!") },
+            { ExpressionNodeType.NotEquals,                new ExpressionNodeInfo(OperationType.Operator,      "!=") },
+            { ExpressionNodeType.Or,                       new ExpressionNodeInfo(OperationType.Operator,      "||") },
+            { ExpressionNodeType.Subtract,                 new ExpressionNodeInfo(OperationType.Operator,      "-") },
+            { ExpressionNodeType.Absolute,                 new ExpressionNodeInfo(OperationType.Function,      "abs") },
+            { ExpressionNodeType.Acos,                     new ExpressionNodeInfo(OperationType.Function,      "acos") },
+            { ExpressionNodeType.Asin,                     new ExpressionNodeInfo(OperationType.Function,      "asin") },
+            { ExpressionNodeType.Atan,                     new ExpressionNodeInfo(OperationType.Function,      "atan") },
+            { ExpressionNodeType.Cos,                      new ExpressionNodeInfo(OperationType.Function,      "cos") },
+            { ExpressionNodeType.Ceil,                     new ExpressionNodeInfo(OperationType.Function,      "ceil") },
+            { ExpressionNodeType.Clamp,                    new ExpressionNodeInfo(OperationType.Function,      "clamp") },
+            { ExpressionNodeType.ColorHsl,                 new ExpressionNodeInfo(OperationType.Function,      "colorhsl") },
+            { ExpressionNodeType.ColorRgb,                 new ExpressionNodeInfo(OperationType.Function,      "colorrgb") },
+            { ExpressionNodeType.ColorLerp,                new ExpressionNodeInfo(OperationType.Function,      "colorlerp") },
+            { ExpressionNodeType.ColorLerpHsl,             new ExpressionNodeInfo(OperationType.Function,      "colorhsllerp") },
+            { ExpressionNodeType.ColorLerpRgb,             new ExpressionNodeInfo(OperationType.Function,      "colorrgblerp") },
+            { ExpressionNodeType.Concatenate,              new ExpressionNodeInfo(OperationType.Function,      "concatenate") },
+            { ExpressionNodeType.Distance,                 new ExpressionNodeInfo(OperationType.Function,      "distance") },
+            { ExpressionNodeType.DistanceSquared,          new ExpressionNodeInfo(OperationType.Function,      "distancesquared") },
+            { ExpressionNodeType.Floor,                    new ExpressionNodeInfo(OperationType.Function,      "floor") },
+            { ExpressionNodeType.Inverse,                  new ExpressionNodeInfo(OperationType.Function,      "inverse") },
+            { ExpressionNodeType.Length,                   new ExpressionNodeInfo(OperationType.Function,      "length") },
+            { ExpressionNodeType.LengthSquared,            new ExpressionNodeInfo(OperationType.Function,      "lengthsquared") },
+            { ExpressionNodeType.Lerp,                     new ExpressionNodeInfo(OperationType.Function,      "lerp") },
+            { ExpressionNodeType.Ln,                       new ExpressionNodeInfo(OperationType.Function,      "ln") },
+            { ExpressionNodeType.Log10,                    new ExpressionNodeInfo(OperationType.Function,      "log10") },
+            { ExpressionNodeType.Max,                      new ExpressionNodeInfo(OperationType.Function,      "max") },
+            { ExpressionNodeType.Matrix3x2FromRotation,    new ExpressionNodeInfo(OperationType.Function,      "matrix3x2.createrotation") },
+            { ExpressionNodeType.Matrix3x2FromScale,       new ExpressionNodeInfo(OperationType.Function,      "matrix3x2.createscale") },
+            { ExpressionNodeType.Matrix3x2FromSkew,        new ExpressionNodeInfo(OperationType.Function,      "matrix3x2.createskew") },
+            { ExpressionNodeType.Matrix3x2FromTranslation, new ExpressionNodeInfo(OperationType.Function,      "matrix3x2.createtranslation") },
+            { ExpressionNodeType.Matrix3x2,                new ExpressionNodeInfo(OperationType.Function,      "matrix3x2") },
+            { ExpressionNodeType.Matrix4x4FromAxisAngle,   new ExpressionNodeInfo(OperationType.Function,      "matrix4x4.createfromaxisangle") },
+            { ExpressionNodeType.Matrix4x4FromScale,       new ExpressionNodeInfo(OperationType.Function,      "matrix4x4.createscale") },
+            { ExpressionNodeType.Matrix4x4FromTranslation, new ExpressionNodeInfo(OperationType.Function,      "matrix4x4.createtranslation") },
+            { ExpressionNodeType.Matrix4x4,                new ExpressionNodeInfo(OperationType.Function,      "matrix4x4") },
+            { ExpressionNodeType.Min,                      new ExpressionNodeInfo(OperationType.Function,      "min") },
+            { ExpressionNodeType.Modulus,                  new ExpressionNodeInfo(OperationType.Function,      "mod") },
+            { ExpressionNodeType.Negate,                   new ExpressionNodeInfo(OperationType.Function,      "-") },
+            { ExpressionNodeType.Normalize,                new ExpressionNodeInfo(OperationType.Function,      "normalize") },
+            { ExpressionNodeType.Pow,                      new ExpressionNodeInfo(OperationType.Function,      "pow") },
+            { ExpressionNodeType.QuaternionFromAxisAngle,  new ExpressionNodeInfo(OperationType.Function,      "quaternion.createfromaxisangle") },
+            { ExpressionNodeType.Quaternion,               new ExpressionNodeInfo(OperationType.Function,      "quaternion") },
+            { ExpressionNodeType.Round,                    new ExpressionNodeInfo(OperationType.Function,      "round") },
+            { ExpressionNodeType.Scale,                    new ExpressionNodeInfo(OperationType.Function,      "scale") },
+            { ExpressionNodeType.Sin,                      new ExpressionNodeInfo(OperationType.Function,      "sin") },
+            { ExpressionNodeType.Slerp,                    new ExpressionNodeInfo(OperationType.Function,      "slerp") },
+            { ExpressionNodeType.Sqrt,                     new ExpressionNodeInfo(OperationType.Function,      "sqrt") },
+            { ExpressionNodeType.Square,                   new ExpressionNodeInfo(OperationType.Function,      "square") },
+            { ExpressionNodeType.Tan,                      new ExpressionNodeInfo(OperationType.Function,      "tan") },
+            { ExpressionNodeType.ToDegrees,                new ExpressionNodeInfo(OperationType.Function,      "todegrees") },
+            { ExpressionNodeType.ToRadians,                new ExpressionNodeInfo(OperationType.Function,      "toradians") },
+            { ExpressionNodeType.Transform,                new ExpressionNodeInfo(OperationType.Function,      "transform") },
+            { ExpressionNodeType.Vector2,                  new ExpressionNodeInfo(OperationType.Function,      "vector2") },
+            { ExpressionNodeType.Vector3,                  new ExpressionNodeInfo(OperationType.Function,      "vector3") },
+            { ExpressionNodeType.Vector4,                  new ExpressionNodeInfo(OperationType.Function,      "vector4") },
         };
     }
 }

Microsoft.Toolkit.Uwp.UI.Animations/Expressions/ExpressionNodes/ExpressionNode.cs

@@ -502,6 +502,15 @@ private string ToExpressionStringInternal()
                     ret = $"({Children[0].ToExpressionStringInternal()} {GetOperationString()} {Children[1].ToExpressionStringInternal()})";
                     break;
 
+                case OperationType.UnaryOperator:
+                    if (Children.Count != 1)
+                    {
+                        throw new Exception("Can't have an unary operator that doesn't have exactly one params");
+                    }
+
+                    ret = $"( {GetOperationString()} {Children[0].ToExpressionStringInternal()} )";
+                    break;
+
                 case OperationType.Constant:
                     if (Children.Count == 0)
                     {

Microsoft.Toolkit.Uwp.UI.Animations/Expressions/OperationType.cs

@@ -15,10 +15,15 @@ internal enum OperationType
         Function,
 
         /// <summary>
-        /// The operator
+        /// The operator (takes two operands)
         /// </summary>
         Operator,
 
+        /// <summary>
+        /// The operator that only takes one operand
+        /// </summary>
+        UnaryOperator,
+
         /// <summary>
         /// The constant
         /// </summary>