Add Simple Expression constraint

src/libraries/Microsoft.PowerFx.Core/Binding/BindKind.cs

@@ -85,4 +85,16 @@ internal enum BindKind
 
         Lim,
     }
+
+    internal static class BindKindExtensions
+    {
+        internal static bool IsValidInSimpleExpression(this BindKind kind)
+        {
+            // Starting simple, we could expand this set over time. 
+            return kind == BindKind.ThisItem ||
+                kind == BindKind.Enum ||
+                kind == BindKind.LambdaField ||
+                kind == BindKind.LambdaFullRecord;
+        }
+    }
 }

src/libraries/Microsoft.PowerFx.Core/Binding/Binder.cs

@@ -1061,8 +1061,7 @@ internal bool TryGetDataSourceInfo(TexlNode node, out IExternalDataSource dataSo
                     return dataSourceInfo != null;
 
                 case NodeKind.DottedName:
-                    IExpandInfo info;
-                    if (TryGetEntityInfo(node.AsDottedName(), out info))
+                    if (TryGetEntityInfo(node.AsDottedName(), out IExpandInfo info))
                     {
                         dataSourceInfo = info.ParentDataSource;
                         return dataSourceInfo != null;
@@ -2897,6 +2896,16 @@ public override void Visit(FirstNameNode node)
                     _txb.SetType(node, DType.Error);
                     _txb.SetInfo(node, FirstNameInfo.Create(node, default(NameLookupInfo)));
                     return;
+                }
+
+                // We have an allowlist of kinds permitted in simple expressions, all of which should be Sync. 
+                // The IsAsync check is just to be sure we're not introducing async
+                // if things are added to the set of valid kinds in the future.
+                // As the main point of the "Simple Expression" constraint is to ensure certain expressions are sync
+                // but that's harder to communicate to low-code users.
+                if (_txb.BindingConfig.EnforceSimpleExpressionConstraint && (!lookupInfo.Kind.IsValidInSimpleExpression() || lookupInfo.IsAsync))
+                {
+                    _txb.ErrorContainer.Error(node, TexlStrings.ErrViolatedSimpleConstraintAccess, node.Ident.Name.Value);
                 }
 
                 var isConstantNamedFormula = false;
@@ -4849,9 +4858,14 @@ private void FinalizeCall(CallNode node)
                 else if (func.IsTestOnly && _txb.Property != null && !_txb.Property.IsTestCaseProperty)
                 {
                     _txb.ErrorContainer.EnsureError(node, TexlStrings.ErrTestPropertyExpected);
+                }
+                else if ((!func.IsAllowedInSimpleExpressions || _txb.IsAsync(node)) && _txb.BindingConfig.EnforceSimpleExpressionConstraint)
+                {
+                    // Functions that are not allowed in simple expressions cannot be used when the binding config restricts to simple expressions.
+                    _txb.ErrorContainer.EnsureError(node, TexlStrings.ErrViolatedSimpleConstraintFunction, func.Name);
                 }
-
-                // Auto-refreshable functions cannot be used in behavior rules.
+
+                // Auto-refreshable functions cannot be used in behavior rules.
                 else if (func.IsAutoRefreshable && _txb.BindingConfig.AllowsSideEffects)
                 {
                     _txb.ErrorContainer.EnsureError(node, TexlStrings.ErrAutoRefreshNotAllowed);

src/libraries/Microsoft.PowerFx.Core/Binding/BindingConfig.cs

@@ -25,16 +25,31 @@ internal class BindingConfig
 
         public bool MarkAsAsyncOnLazilyLoadedControlRef { get; } = false;
 
-        public bool UserDefinitionsMode { get; }
+        public bool UserDefinitionsMode { get; }
+
+        /// <summary>
+        /// Enforces the expression must be "Simple", i.e. no async, no global access, no impure functions
+        /// This is mainly used for controls like combobox where the expression is used to populate a dropdown
+        /// and must be FAST to run on large datasets.
+        /// </summary>
+        internal bool EnforceSimpleExpressionConstraint { get; }
 
-        public BindingConfig(bool allowsSideEffects = false, bool useThisRecordForRuleScope = false, bool numberIsFloat = false, bool analysisMode = false, bool markAsAsyncOnLazilyLoadedControlRef = false, bool userDefinitionsMode = false)
+        public BindingConfig(
+            bool allowsSideEffects = false,
+            bool useThisRecordForRuleScope = false,
+            bool numberIsFloat = false,
+            bool analysisMode = false,
+            bool markAsAsyncOnLazilyLoadedControlRef = false,
+            bool userDefinitionsMode = false,
+            bool enforceSimpleExpressions = false)
         {
             AllowsSideEffects = allowsSideEffects;
             UseThisRecordForRuleScope = useThisRecordForRuleScope;
             NumberIsFloat = numberIsFloat;
             AnalysisMode = analysisMode;
             MarkAsAsyncOnLazilyLoadedControlRef = markAsAsyncOnLazilyLoadedControlRef;
-            UserDefinitionsMode = userDefinitionsMode;
+            UserDefinitionsMode = userDefinitionsMode;
+            EnforceSimpleExpressionConstraint = enforceSimpleExpressions;
         }
 
         public BindingConfig Clone(bool allowsSideEffects)
@@ -45,7 +60,8 @@ public BindingConfig Clone(bool allowsSideEffects)
                 numberIsFloat: this.NumberIsFloat,
                 analysisMode: this.AnalysisMode,
                 markAsAsyncOnLazilyLoadedControlRef: this.MarkAsAsyncOnLazilyLoadedControlRef,
-                userDefinitionsMode: this.UserDefinitionsMode);
+                userDefinitionsMode: this.UserDefinitionsMode,
+                enforceSimpleExpressions: this.EnforceSimpleExpressionConstraint);
         }
     }
 }

src/libraries/Microsoft.PowerFx.Core/Functions/TexlFunction.cs

@@ -115,6 +115,11 @@ internal abstract class TexlFunction : IFunction
         // abstract will force them to do so.
         public abstract bool IsSelfContained { get; }
 
+        /// <summary>
+        /// Allowlist for functions that can be used in "simple" expressions.
+        /// </summary>
+        public virtual bool IsAllowedInSimpleExpressions => false;
+
         // Return true if the function is stateless (same result for same input), or false otherwise.
         public virtual bool IsStateless => true;
 

src/libraries/Microsoft.PowerFx.Core/Localization/Strings.cs

@@ -931,5 +931,7 @@ internal static class TexlStrings
         public static ErrorResourceKey ErrJoinArgIsNotAsNode = new ErrorResourceKey("ErrJoinArgIsNotAsNode");
         public static ErrorResourceKey ErrJoinAtLeastOneRigthRecordField = new ErrorResourceKey("ErrJoinAtLeastOneRigthRecordField");
         public static ErrorResourceKey ErrJoinDottedNameleft = new ErrorResourceKey("ErrJoinDottedNameleft");
+        public static ErrorResourceKey ErrViolatedSimpleConstraintAccess = new ErrorResourceKey("ErrViolatedSimpleConstraintAccess");
+        public static ErrorResourceKey ErrViolatedSimpleConstraintFunction = new ErrorResourceKey("ErrViolatedSimpleConstraintFunction");
     }
 }

src/libraries/Microsoft.PowerFx.Core/Public/CheckResult.cs

@@ -766,8 +766,8 @@ public IEnumerable<string> GetFunctionNames(bool anonymizeUnknownPublicFunctions
     // for error reporting. 
     internal interface IOperationStatus
     {
-        public IEnumerable<ExpressionError> Errors { get; }
+        IEnumerable<ExpressionError> Errors { get; }
 
-        public bool IsSuccess { get; }
+        bool IsSuccess { get; }
     }
 }

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Boolean.cs

@@ -26,7 +26,9 @@ internal sealed class BooleanFunction : BuiltinFunction
 
         public override bool IsSelfContained => true;
 
-        public override bool SupportsParamCoercion => false;
+        public override bool SupportsParamCoercion => false;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public BooleanFunction()
             : base(BooleanInvariantFunctionName, TexlStrings.AboutBoolean, FunctionCategories.Text, DType.Boolean, 0, 1, 1, DType.String)
@@ -86,7 +88,9 @@ internal sealed class BooleanNFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool SupportsParamCoercion => false;
+        public override bool SupportsParamCoercion => false;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public BooleanNFunction()
             : base(BooleanFunction.BooleanInvariantFunctionName, TexlStrings.AboutBooleanN, FunctionCategories.Text, DType.Boolean, 0, 1, 1, DType.Number)
@@ -153,7 +157,9 @@ internal sealed class BooleanWFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool SupportsParamCoercion => false;
+        public override bool SupportsParamCoercion => false;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         // Reusing BooleanN strings as they are generic for numbers
         public BooleanWFunction()
@@ -225,7 +231,9 @@ internal sealed class BooleanBFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool SupportsParamCoercion => false;
+        public override bool SupportsParamCoercion => false;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public BooleanBFunction()
             : base(BooleanFunction.BooleanInvariantFunctionName, TexlStrings.AboutBooleanB, FunctionCategories.Text, DType.Boolean, 0, 1, 1, DType.Boolean)
@@ -326,7 +334,9 @@ internal sealed class BooleanLFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool SupportsParamCoercion => false;
+        public override bool SupportsParamCoercion => false;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public BooleanLFunction()
             : base(BooleanFunction.BooleanInvariantFunctionName, TexlStrings.AboutBooleanL, FunctionCategories.Text, DType.Boolean, 0, 1, 1, DType.OptionSetValue)
@@ -411,7 +421,9 @@ internal sealed class BooleanFunction_UO : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool SupportsParamCoercion => false;
+        public override bool SupportsParamCoercion => false;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public BooleanFunction_UO()
             : base(BooleanFunction.BooleanInvariantFunctionName, TexlStrings.AboutBoolean, FunctionCategories.Text, DType.Boolean, 0, 1, 1, DType.UntypedObject)

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Char.cs

@@ -26,6 +26,8 @@ public override ArgPreprocessor GetArgPreprocessor(int index, int argCount)
 
         public override bool IsSelfContained => true;
 
+        public override bool IsAllowedInSimpleExpressions => true;
+
         public CharFunction()
             : base("Char", TexlStrings.AboutChar, FunctionCategories.Text, DType.String, 0, 1, 1, DType.Number)
         {

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Concatenate.cs

@@ -22,6 +22,8 @@ internal sealed class ConcatenateFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
+        public override bool IsAllowedInSimpleExpressions => true;
+
         public ConcatenateFunction()
             : base("Concatenate", TexlStrings.AboutConcatenate, FunctionCategories.Text, DType.String, 0, 1, int.MaxValue)
         {

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/DateTime.cs

@@ -28,7 +28,9 @@ public override ArgPreprocessor GetArgPreprocessor(int index, int argCount)
 
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public DateFunction()
             : base("Date", TexlStrings.AboutDate, FunctionCategories.DateTime, DType.Date, 0, 3, 3, DType.Number, DType.Number, DType.Number)
@@ -46,7 +48,9 @@ internal abstract class ExtractDateTimeFunctionBase : BuiltinFunction
     {
         public override bool HasPreciseErrors => true;
 
-        public override bool IsSelfContained => true;
+        public override bool IsSelfContained => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public ExtractDateTimeFunctionBase(string name, TexlStrings.StringGetter description)
             : base(name, description, FunctionCategories.DateTime, DType.Number, 0, 1, 1, DType.DateTime)
@@ -86,7 +90,9 @@ public override ArgPreprocessor GetArgPreprocessor(int index, int argCount)
 
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public TimeFunction()
             : base("Time", TexlStrings.AboutTime, FunctionCategories.DateTime, DType.Time, 0, 3, 4, DType.Number, DType.Number, DType.Number, DType.Number)
@@ -110,7 +116,9 @@ public override ArgPreprocessor GetArgPreprocessor(int index, int argCount)
 
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public DateTimeFunction()
             : base("DateTime", TexlStrings.AboutDateTime, FunctionCategories.DateTime, DType.DateTime, 0, 6, 7, DType.Number, DType.Number, DType.Number, DType.Number, DType.Number, DType.Number, DType.Number)
@@ -232,7 +240,9 @@ internal sealed class WeekdayFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public WeekdayFunction()
             : base("Weekday", TexlStrings.AboutWeekday, FunctionCategories.DateTime, DType.Number, 0, 1, 2, DType.DateTime, BuiltInEnums.StartOfWeekEnum.FormulaType._type)
@@ -269,7 +279,9 @@ internal sealed class WeekNumFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public WeekNumFunction()
             : base("WeekNum", TexlStrings.AboutWeekNum, FunctionCategories.DateTime, DType.Number, 0, 1, 2, DType.DateTime, BuiltInEnums.StartOfWeekEnum.FormulaType._type)
@@ -367,7 +379,9 @@ internal abstract class DateTimeGenericFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         protected DateTimeGenericFunction(string name, TexlStrings.StringGetter description, DType returnType)
             : base(name, description, FunctionCategories.DateTime, returnType, 0, 1, 2, DType.String, DType.String)
@@ -445,7 +459,9 @@ public DateTimeValueFunction()
     // DateAdd(timestamp: d, delta: n, [ unit: TimeUnits ]) : d
     internal sealed class DateAddFunction : BuiltinFunction
     {
-        public override bool IsSelfContained => true;
+        public override bool IsSelfContained => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public DateAddFunction()
             : base("DateAdd", TexlStrings.AboutDateAdd, FunctionCategories.DateTime, DType.DateTime, 0, 2, 3, DType.DateTime, DType.Number, BuiltInEnums.TimeUnitEnum.FormulaType._type)
@@ -627,7 +643,9 @@ internal sealed class DateDiffFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
-        public override bool HasPreciseErrors => true;
+        public override bool HasPreciseErrors => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public DateDiffFunction()
             : base("DateDiff", TexlStrings.AboutDateDiff, FunctionCategories.DateTime, DType.Number, 0, 2, 3, DType.DateTime, DType.DateTime, BuiltInEnums.TimeUnitEnum.FormulaType._type)
@@ -784,7 +802,9 @@ internal sealed class DateValueFunction_UO : BuiltinFunction
     {
         public override bool HasPreciseErrors => true;
 
-        public override bool IsSelfContained => true;
+        public override bool IsSelfContained => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public DateValueFunction_UO()
             : base(DateValueFunction.DateValueInvariantFunctionName, TexlStrings.AboutDateValue, FunctionCategories.DateTime, DType.Date, 0, 1, 1, DType.UntypedObject)
@@ -802,7 +822,9 @@ internal sealed class TimeValueFunction_UO : BuiltinFunction
     {
         public override bool HasPreciseErrors => true;
 
-        public override bool IsSelfContained => true;
+        public override bool IsSelfContained => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public TimeValueFunction_UO()
             : base(TimeValueFunction.TimeValueFunctionInvariantName, TexlStrings.AboutTimeValue, FunctionCategories.DateTime, DType.Time, 0, 1, 1, DType.UntypedObject)
@@ -820,7 +842,9 @@ internal sealed class DateTimeValueFunction_UO : BuiltinFunction
     {
         public override bool HasPreciseErrors => true;
 
-        public override bool IsSelfContained => true;
+        public override bool IsSelfContained => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public DateTimeValueFunction_UO()
             : base(DateTimeValueFunction.DateTimeValueInvariantFunctionName, TexlStrings.AboutDateTimeValue, FunctionCategories.DateTime, DType.DateTime, 0, 1, 1, DType.UntypedObject)

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Dec2Hex.cs

@@ -27,6 +27,8 @@ public override ArgPreprocessor GetArgPreprocessor(int index, int argCount)
 
         public override bool HasPreciseErrors => true;
 
+        public override bool IsAllowedInSimpleExpressions => true;
+
         public Dec2HexFunction()
             : base("Dec2Hex", TexlStrings.AboutDec2Hex, FunctionCategories.MathAndStat, DType.String, 0, 1, 2, DType.Number, DType.Number)
         {

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Find.cs

@@ -22,6 +22,8 @@ internal sealed class FindFunction : BuiltinFunction
     {
         public override bool IsSelfContained => true;
 
+        public override bool IsAllowedInSimpleExpressions => true;
+
         public FindFunction()
             : base("Find", TexlStrings.AboutFind, FunctionCategories.Text, DType.Number, 0, 2, 3, DType.String, DType.String, DType.Number)
         {

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Hex2Dec.cs

@@ -23,7 +23,9 @@ public override ArgPreprocessor GetArgPreprocessor(int index, int argCount)
 
         public override bool IsSelfContained => true;
 
-        public override bool IsStateless => true;
+        public override bool IsStateless => true;
+
+        public override bool IsAllowedInSimpleExpressions => true;
 
         public Hex2DecFunction()
             : base("Hex2Dec", TexlStrings.AboutHex2Dec, FunctionCategories.MathAndStat, DType.Number, 0, 1, 1, DType.String)

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/If.cs

@@ -27,6 +27,8 @@ internal sealed class IfFunction : BuiltinFunction
 
         public override bool IsSelfContained => true;
 
+        public override bool IsAllowedInSimpleExpressions => true;
+
         public IfFunction()
             : base("If", TexlStrings.AboutIf, FunctionCategories.Logical, DType.Unknown, 0, 2, int.MaxValue)
         {

src/libraries/Microsoft.PowerFx.Core/Texl/Builtins/Logical.cs

@@ -23,6 +23,8 @@ internal sealed class VariadicLogicalFunction : BuiltinFunction
 
         public override bool IsSelfContained => true;
 
+        public override bool IsAllowedInSimpleExpressions => true;
+
         internal readonly bool _isAnd;
 
         public VariadicLogicalFunction(bool isAnd)