Improve formatting for known enum members

Author: Sergio0694

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Extensions/ITypeSymbolExtensions.cs

@@ -34,7 +34,7 @@ public static bool TryGetDefaultValueForEnumType(this ITypeSymbol symbol, [NotNu
     {
         if (symbol.TypeKind is not TypeKind.Enum)
         {
-            value = default;
+            value = null;
 
             return false;
         }
@@ -50,7 +50,43 @@ public static bool TryGetDefaultValueForEnumType(this ITypeSymbol symbol, [NotNu
             }
         }
 
-        value = default;
+        value = null;
+
+        return false;
+    }
+
+    /// <summary>
+    /// Tries to get the name of the enum field matching a given value.
+    /// </summary>
+    /// <param name="symbol">The input <see cref="ITypeSymbol"/> instance to check.</param>
+    /// <param name="value">The value for to try to get the field for.</param>
+    /// <param name="fieldName">The name of the field with the specified value, if found.</param>
+    /// <returns>Whether <paramref name="fieldName"/> was successfully retrieved.</returns>
+    public static bool TryGetEnumFieldName(this ITypeSymbol symbol, object value, [NotNullWhen(true)] out string? fieldName)
+    {
+        if (symbol.TypeKind is not TypeKind.Enum)
+        {
+            fieldName = null;
+
+            return false;
+        }
+
+        // The default value of the enum is the value of its first constant field
+        foreach (ISymbol memberSymbol in symbol.GetMembers())
+        {
+            if (memberSymbol is not IFieldSymbol { IsConst: true, ConstantValue: object fieldValue } fieldSymbol)
+            {
+                continue;
+            }
+
+            if (fieldValue == value)
+            {
+                fieldName = fieldSymbol.Name;
+
+                return true;
+            }
+        }
+        fieldName = null;
 
         return false;
     }

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Models/TypedConstantInfo.Factory.cs

@@ -6,6 +6,7 @@
 using System.Collections.Immutable;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
+using CommunityToolkit.GeneratedDependencyProperty.Extensions;
 using Microsoft.CodeAnalysis;
 
 namespace CommunityToolkit.GeneratedDependencyProperty.Models;
@@ -53,8 +54,12 @@ public static TypedConstantInfo Create(TypedConstant arg)
                 ushort ush => new Primitive.Of<ushort>(ush),
                 _ => throw new ArgumentException("Invalid primitive type")
             },
-            (TypedConstantKind.Type, ITypeSymbol type) => new Type(type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)),
-            (TypedConstantKind.Enum, object value) => new Enum(arg.Type!.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), value),
+            (TypedConstantKind.Type, ITypeSymbol type)
+                => new Type(type.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat)),
+            (TypedConstantKind.Enum, object value) when arg.Type!.TryGetEnumFieldName(value, out string? fieldName)
+                => new KnownEnum(arg.Type!.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), fieldName),
+            (TypedConstantKind.Enum, object value)
+                => new Enum(arg.Type!.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), value),
             _ => throw new ArgumentException("Invalid typed constant type"),
         };
     }
@@ -87,7 +92,10 @@ public static bool TryCreate(IOperation operation, [NotNullWhen(true)] out Typed
         {
             ({ SpecialType: SpecialType.System_String }, string text) => new Primitive.String(text),
             ({ SpecialType: SpecialType.System_Boolean}, bool flag) => new Primitive.Boolean(flag),
-            (INamedTypeSymbol { TypeKind: TypeKind.Enum }, object value) => new Enum(operationType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), value),
+            (INamedTypeSymbol { TypeKind: TypeKind.Enum }, object value) when (operationType.TryGetEnumFieldName(value, out string? fieldName))
+                => new KnownEnum(operationType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), fieldName),
+            (INamedTypeSymbol { TypeKind: TypeKind.Enum }, object value)
+                => new Enum(operationType.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), value),
             (_, byte b) => new Primitive.Of<byte>(b),
             (_, char c) => new Primitive.Of<char>(c),
             (_, double d) => new Primitive.Of<double>(d),

components/DependencyPropertyGenerator/CommunityToolkit.DependencyPropertyGenerator.SourceGenerators/Models/TypedConstantInfo.cs

@@ -138,6 +138,20 @@ public override string ToString()
         }
     }
 
+    /// <summary>
+    /// A <see cref="TypedConstantInfo"/> type representing a known enum value.
+    /// </summary>
+    /// <param name="TypeName">The enum type name.</param>
+    /// <param name="FieldName">The enum field name.</param>
+    public sealed record KnownEnum(string TypeName, string FieldName) : TypedConstantInfo
+    {
+        /// <inheritdoc/>
+        public override string ToString()
+        {
+            return $"{TypeName}.{FieldName}";
+        }
+    }
+
     /// <summary>
     /// A <see cref="TypedConstantInfo"/> type representing an enum value.
     /// </summary>