Refactor KeywordsHelper, TypeFinder and update comments on ParsingConfig

src/System.Linq.Dynamic.Core/DynamicQueryableExtensions.cs

@@ -9,6 +9,7 @@
 using JetBrains.Annotations;
 using System.Linq.Dynamic.Core.Parser;
 using System.Linq.Dynamic.Core.Util;
+
 #if !(SILVERLIGHT)
 using System.Diagnostics;
 #endif
@@ -314,7 +315,7 @@ public static IQueryable Cast(this IQueryable source, Type type)
             Check.NotNull(source);
             Check.NotNull(type);
 
-            var optimized = OptimizeExpression(Expression.Call(null, _cast.MakeGenericMethod(new[] { type }), new[] { source.Expression }));
+            var optimized = OptimizeExpression(Expression.Call(null, _cast.MakeGenericMethod(type), source.Expression));
 
             return source.Provider.CreateQuery(optimized);
         }
@@ -330,10 +331,13 @@ public static IQueryable Cast(this IQueryable source, ParsingConfig config, stri
         {
             Check.NotNull(source);
             Check.NotNull(config);
-            Check.NotEmpty(typeName, nameof(typeName));
+            Check.NotEmpty(typeName);
 
             var finder = new TypeFinder(config, new KeywordsHelper(config));
-            Type type = finder.FindTypeByName(typeName, null, true)!;
+            if (!finder.TryFindTypeByName(typeName, null, true, out var type))
+            {
+                throw new ParseException(string.Format(CultureInfo.CurrentCulture, Res.TypeNotFound, typeName));
+            }
 
             return Cast(source, type);
         }
@@ -1445,7 +1449,10 @@ public static IQueryable OfType(this IQueryable source, ParsingConfig config, st
             Check.NotEmpty(typeName);
 
             var finder = new TypeFinder(config, new KeywordsHelper(config));
-            Type type = finder.FindTypeByName(typeName, null, true)!;
+            if (!finder.TryFindTypeByName(typeName, null, true, out var type))
+            {
+                throw new ParseException(string.Format(CultureInfo.CurrentCulture, Res.TypeNotFound, typeName));
+            }
 
             return OfType(source, type);
         }

src/System.Linq.Dynamic.Core/Exceptions/ParseException.cs

@@ -4,74 +4,85 @@
 using System.Runtime.Serialization;
 #endif
 
-namespace System.Linq.Dynamic.Core.Exceptions
+namespace System.Linq.Dynamic.Core.Exceptions;
+
+/// <summary>
+/// Represents errors that occur while parsing dynamic linq string expressions.
+/// </summary>
+#if !(SILVERLIGHT || UAP10_0 || NETSTANDARD || PORTABLE || WPSL || NETSTANDARD2_0)
+[Serializable]
+#endif
+public sealed class ParseException : Exception
 {
+    private const int UnknownPosition = -1;
+
     /// <summary>
-    /// Represents errors that occur while parsing dynamic linq string expressions.
+    /// The location in the parsed string that produced the <see cref="ParseException"/>.
+    /// If the value is <c>-1</c>, the position is unknown.
     /// </summary>
-#if !(SILVERLIGHT || UAP10_0 || NETSTANDARD || PORTABLE || WPSL || NETSTANDARD2_0)
-    [Serializable]
-#endif
-    public sealed class ParseException : Exception
+    public int Position { get; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ParseException"/> class with a specified error message and position.
+    /// </summary>
+    /// <param name="message">The message that describes the error.</param>
+    /// <param name="innerException">The exception that is the cause of the current exception, or a null reference if no inner exception is specified.</param>
+    public ParseException(string message, Exception? innerException = null) : this(message, UnknownPosition, innerException)
     {
-        /// <summary>
-        /// The location in the parsed string that produced the <see cref="ParseException"/>.
-        /// </summary>
-        public int Position { get; }
+    }
 
-        /// <summary>
-        /// Initializes a new instance of the <see cref="ParseException"/> class with a specified error message and position.
-        /// </summary>
-        /// <param name="message">The message that describes the error.</param>
-        /// <param name="position">The location in the parsed string that produced the <see cref="ParseException"/></param>
-        /// <param name="innerException">The exception that is the cause of the current exception, or a null reference if no inner exception is specified.</param>
-        public ParseException(string message, int position, Exception? innerException = null) : base(message, innerException)
+    /// <summary>
+    /// Initializes a new instance of the <see cref="ParseException"/> class with a specified error message and position.
+    /// </summary>
+    /// <param name="message">The message that describes the error.</param>
+    /// <param name="position">The location in the parsed string that produced the <see cref="ParseException"/></param>
+    /// <param name="innerException">The exception that is the cause of the current exception, or a null reference if no inner exception is specified.</param>
+    public ParseException(string message, int position, Exception? innerException = null) : base(message, innerException)
+    {
+        Position = position;
+    }
+
+    /// <summary>
+    /// Creates and returns a string representation of the current exception.
+    /// </summary>
+    /// <returns>A string representation of the current exception.</returns>
+    public override string ToString()
+    {
+        var text = string.Format(CultureInfo.CurrentCulture, Res.ParseExceptionFormat, Message, Position);
+
+        if (InnerException != null)
         {
-            Position = position;
+            text = $"{text} ---> {InnerException}{Environment.NewLine}   --- End of inner exception stack trace ---";
         }
 
-        /// <summary>
-        /// Creates and returns a string representation of the current exception.
-        /// </summary>
-        /// <returns>A string representation of the current exception.</returns>
-        public override string ToString()
+        if (StackTrace != null)
         {
-            var text = string.Format(CultureInfo.CurrentCulture, Res.ParseExceptionFormat, Message, Position);
-
-            if (InnerException != null)
-            {
-                text = $"{text} ---> {InnerException}{Environment.NewLine}   --- End of inner exception stack trace ---";
-            }
-
-            if (StackTrace != null)
-            {
-                text = $"{text}{Environment.NewLine}{StackTrace}";
-            }
-
-            return text;
+            text = $"{text}{Environment.NewLine}{StackTrace}";
         }
 
+        return text;
+    }
+
 #if !(SILVERLIGHT || UAP10_0 || NETSTANDARD || PORTABLE || WPSL || NETSTANDARD2_0)
-        private ParseException(SerializationInfo info, StreamingContext context) : base(info, context)
-        {
-            Position = (int)info.GetValue("position", typeof(int));
-        }
+    private ParseException(SerializationInfo info, StreamingContext context) : base(info, context)
+    {
+        Position = (int)info.GetValue("position", typeof(int))!;
+    }
 
-        /// <summary>
-        /// When overridden in a derived class, sets the <see cref="T:System.Runtime.Serialization.SerializationInfo" /> with information about the exception.
-        /// </summary>
-        /// <param name="info">The <see cref="T:System.Runtime.Serialization.SerializationInfo" /> that holds the serialized object data about the exception being thrown.</param>
-        /// <param name="context">The <see cref="T:System.Runtime.Serialization.StreamingContext" /> that contains contextual information about the source or destination.</param>
-        /// <PermissionSet>
-        ///   <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="*AllFiles*" PathDiscovery="*AllFiles*" />
-        ///   <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="SerializationFormatter" />
-        /// </PermissionSet>
-        public override void GetObjectData(SerializationInfo info, StreamingContext context)
-        {
-            base.GetObjectData(info, context);
+    /// <summary>
+    /// When overridden in a derived class, sets the <see cref="T:System.Runtime.Serialization.SerializationInfo" /> with information about the exception.
+    /// </summary>
+    /// <param name="info">The <see cref="T:System.Runtime.Serialization.SerializationInfo" /> that holds the serialized object data about the exception being thrown.</param>
+    /// <param name="context">The <see cref="T:System.Runtime.Serialization.StreamingContext" /> that contains contextual information about the source or destination.</param>
+    /// <PermissionSet>
+    ///   <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Read="*AllFiles*" PathDiscovery="*AllFiles*" />
+    ///   <IPermission class="System.Security.Permissions.SecurityPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Flags="SerializationFormatter" />
+    /// </PermissionSet>
+    public override void GetObjectData(SerializationInfo info, StreamingContext context)
+    {
+        base.GetObjectData(info, context);
 
-            info.AddValue("position", Position);
-        }
-#endif
+        info.AddValue("position", Position);
     }
-}
+#endif
+}

src/System.Linq.Dynamic.Core/Parser/ExpressionParser.cs

@@ -906,8 +906,7 @@ private AnyOf<Expression, Type> ParseStringLiteral(bool forceParseAsString)
         if (_parsingConfig.SupportCastingToFullyQualifiedTypeAsString && !forceParseAsString && parsedStringValue.Length > 2 && parsedStringValue.Contains('.'))
         {
             // Try to resolve this string as a type
-            var type = _typeFinder.FindTypeByName(parsedStringValue, null, false);
-            if (type is { })
+            if (_typeFinder.TryFindTypeByName(parsedStringValue, null, false, out var type))
             {
                 return type;
             }
@@ -970,7 +969,7 @@ private Expression ParseIdentifier()
     {
         _textParser.ValidateToken(TokenId.Identifier);
 
-        var isValidKeyWord = _keywordsHelper.TryGetValue(_textParser.CurrentToken.Text, out var keywordOrType);
+        var isValid = _keywordsHelper.TryGetValue(_textParser.CurrentToken.Text, out var keywordOrType);
         var shouldPrioritizeType = true;
 
         if (_parsingConfig.PrioritizePropertyOrFieldOverTheType && keywordOrType.IsThird)
@@ -983,7 +982,7 @@ private Expression ParseIdentifier()
             }
         }
 
-        if (isValidKeyWord && shouldPrioritizeType)
+        if (isValid && shouldPrioritizeType)
         {
             var keywordOrFunctionAllowed = !_usedForOrderBy || _usedForOrderBy && !_parsingConfig.RestrictOrderByToPropertyOrField;
             if (!keywordOrFunctionAllowed)
@@ -1397,8 +1396,7 @@ private Expression ParseNew()
                 _textParser.NextToken();
             }
 
-            newType = _typeFinder.FindTypeByName(newTypeName, new[] { _it, _parent, _root }, false);
-            if (newType == null)
+            if (!_typeFinder.TryFindTypeByName(newTypeName, [_it, _parent, _root], false, out newType))
             {
                 throw ParseError(_textParser.CurrentToken.Pos, Res.TypeNotFound, newTypeName);
             }
@@ -1543,14 +1541,15 @@ private Expression CreateNewExpression(List<DynamicProperty> properties, List<Ex
         {
             propertyInfos = propertyInfos.Where(x => x.Name != "Item").ToArray();
         }
+
         var propertyTypes = propertyInfos.Select(p => p.PropertyType).ToArray();
         var ctor = type.GetConstructor(propertyTypes);
         if (ctor != null)
         {
             var constructorParameters = ctor.GetParameters();
             if (constructorParameters.Length == expressions.Count)
             {
-                bool bindParametersSequentially = !properties.All(p => constructorParameters
+                var bindParametersSequentially = !properties.All(p => constructorParameters
                     .Any(cp => cp.Name == p.Name && (cp.ParameterType == p.Type || p.Type == Nullable.GetUnderlyingType(cp.ParameterType))));
                 var expressionsPromoted = new List<Expression?>();
 
@@ -1564,9 +1563,10 @@ private Expression CreateNewExpression(List<DynamicProperty> properties, List<Ex
                     else
                     {
                         Type propertyType = constructorParameters[i].ParameterType;
-                        string cParameterName = constructorParameters[i].Name;
+                        var cParameterName = constructorParameters[i].Name;
                         var propertyAndIndex = properties.Select((p, index) => new { p, index })
                             .First(p => p.p.Name == cParameterName && (p.p.Type == propertyType || p.p.Type == Nullable.GetUnderlyingType(propertyType)));
+
                         // Promote from Type to Nullable Type if needed
                         expressionsPromoted.Add(_parsingConfig.ExpressionPromoter.Promote(expressions[propertyAndIndex.index], propertyType, true, true));
                     }
@@ -2027,8 +2027,7 @@ private Expression ParseAsEnumOrNestedClass(string id)
         }
 
         var typeAsString = string.Concat(parts.Take(parts.Count - 2).ToArray());
-        var type = _typeFinder.FindTypeByName(typeAsString, null, true);
-        if (type == null)
+        if (!_typeFinder.TryFindTypeByName(typeAsString, null, true, out var type))
         {
             throw ParseError(_textParser.CurrentToken.Pos, Res.TypeNotFound, typeAsString);
         }
@@ -2233,20 +2232,20 @@ private Type ResolveTypeFromExpressionValue(string functionName, ConstantExpress
 
     private Type ResolveTypeStringFromArgument(string typeName)
     {
-        bool typeIsNullable = false;
+        var typeIsNullable = false;
+
         if (typeName.EndsWith("?"))
         {
             typeName = typeName.TrimEnd('?');
             typeIsNullable = true;
         }
 
-        var resultType = _typeFinder.FindTypeByName(typeName, new[] { _it, _parent, _root }, true);
-        if (resultType == null)
+        if (!_typeFinder.TryFindTypeByName(typeName, [_it, _parent, _root], true, out var type))
         {
             throw ParseError(_textParser.CurrentToken.Pos, Res.TypeNotFound, typeName);
         }
 
-        return typeIsNullable ? TypeHelper.ToNullableType(resultType) : resultType;
+        return typeIsNullable ? TypeHelper.ToNullableType(type) : type;
     }
 
     private Expression[] ParseArgumentList()

src/System.Linq.Dynamic.Core/Parser/IKeywordsHelper.cs

@@ -3,7 +3,7 @@
 
 namespace System.Linq.Dynamic.Core.Parser;
 
-interface IKeywordsHelper
+internal interface IKeywordsHelper
 {
-    bool TryGetValue(string name, out AnyOf<string, Expression, Type> keywordOrType);
+    bool TryGetValue(string text, out AnyOf<string, Expression, Type> value);
 }

src/System.Linq.Dynamic.Core/Parser/ITypeFinder.cs

@@ -1,9 +1,9 @@
-using System.Linq.Expressions;
+using System.Diagnostics.CodeAnalysis;
+using System.Linq.Expressions;
 
-namespace System.Linq.Dynamic.Core.Parser
+namespace System.Linq.Dynamic.Core.Parser;
+
+internal interface ITypeFinder
 {
-    interface ITypeFinder
-    {
-        Type? FindTypeByName(string name, ParameterExpression?[]? expressions, bool forceUseCustomTypeProvider);
-    }
+    bool TryFindTypeByName(string name, ParameterExpression?[]? expressions, bool forceUseCustomTypeProvider, [NotNullWhen(true)] out Type? type);
 }