improve fullnameof and allow namespaced and nested types

docs/docs/configuration/flattening.md

@@ -6,7 +6,7 @@ description: Flatten properties and fields
 # Flattening and unflattening
 
 It is pretty common to flatten objects during mapping, eg. `Car.Make.Id => CarDto.MakeId`.
-Mapperly tries to figure out flattenings automatically by making use of the pascal case C# notation.
+Mapperly tries to figure out flattenings automatically by making use of the PascalCase C# notation.
 If Mapperly can't resolve the target or source property correctly, it is possible to manually configure it by applying the `MapPropertyAttribute`
 by either using the source and target property path names as arrays or using a dot separated property access path string
 
@@ -52,9 +52,9 @@ If multiple `MapNestedProperties` are defined that contain members that match to
 In such a case it is therefore recommended to define the expected property mapping explicitly using a `MapProperty` attribute.
 :::
 
-## Experimental full `nameof`
+## Full `nameof`
 
-Mapperly supports an experimental "fullnameof".
+Mapperly supports a "fullnameof".
 It can be used to configure property paths using `nameof`.
 Opt-in is done by prefixing the path with `@`.
 
@@ -63,11 +63,4 @@ Opt-in is done by prefixing the path with `@`.
 partial CarDto Map(Car car);
 ```
 
-`@nameof(Car.Make.Id)` will result in the property path `Make.Id`.
-The first part of the property path is stripped.
-Make sure these property paths start with the type of the property and not with a namespace or a property.
-
-:::warning
-This is an experimental API.
-Its API surface is not subject to semantic releases and may break in any release.
-:::
+`nameof(@Car.Make.Id)` will result in the property path `Make.Id`.

src/Riok.Mapperly/Configuration/AttributeDataAccessor.cs

@@ -1,6 +1,7 @@
 using System.Reflection;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Operations;
 using Riok.Mapperly.Descriptors;
 using Riok.Mapperly.Helpers;
 
@@ -52,11 +53,11 @@ public IEnumerable<TData> Access<TAttribute, TData>(ISymbol symbol)
         var attrDatas = symbolAccessor.GetAttributes<TAttribute>(symbol);
         foreach (var attrData in attrDatas)
         {
-            yield return Access<TAttribute, TData>(attrData);
+            yield return Access<TAttribute, TData>(attrData, symbolAccessor);
         }
     }
 
-    internal static TData Access<TAttribute, TData>(AttributeData attrData)
+    internal static TData Access<TAttribute, TData>(AttributeData attrData, SymbolAccessor? symbolAccessor = null)
         where TAttribute : Attribute
         where TData : notnull
     {
@@ -68,7 +69,7 @@ internal static TData Access<TAttribute, TData>(AttributeData attrData)
             (IReadOnlyList<AttributeArgumentSyntax>?)syntax?.ArgumentList?.Arguments
             ?? new AttributeArgumentSyntax[attrData.ConstructorArguments.Length + attrData.NamedArguments.Length];
         var typeArguments = (IReadOnlyCollection<ITypeSymbol>?)attrData.AttributeClass?.TypeArguments ?? [];
-        var attr = Create<TData>(typeArguments, attrData.ConstructorArguments, syntaxArguments);
+        var attr = Create<TData>(typeArguments, attrData.ConstructorArguments, syntaxArguments, symbolAccessor);
 
         var syntaxIndex = attrData.ConstructorArguments.Length;
         var propertiesByName = dataType.GetProperties().GroupBy(x => x.Name).ToDictionary(x => x.Key, x => x.First());
@@ -77,7 +78,7 @@ internal static TData Access<TAttribute, TData>(AttributeData attrData)
             if (!propertiesByName.TryGetValue(namedArgument.Key, out var prop))
                 throw new InvalidOperationException($"Could not get property {namedArgument.Key} of attribute {attrType.FullName}");
 
-            var value = BuildArgumentValue(namedArgument.Value, prop.PropertyType, syntaxArguments[syntaxIndex]);
+            var value = BuildArgumentValue(namedArgument.Value, prop.PropertyType, syntaxArguments[syntaxIndex], symbolAccessor);
             prop.SetValue(attr, value);
             syntaxIndex++;
         }
@@ -93,7 +94,8 @@ internal static TData Access<TAttribute, TData>(AttributeData attrData)
     private static TData Create<TData>(
         IReadOnlyCollection<ITypeSymbol> typeArguments,
         IReadOnlyCollection<TypedConstant> constructorArguments,
-        IReadOnlyList<AttributeArgumentSyntax> argumentSyntax
+        IReadOnlyList<AttributeArgumentSyntax> argumentSyntax,
+        SymbolAccessor? symbolAccessor
     )
         where TData : notnull
     {
@@ -110,7 +112,7 @@ IReadOnlyList<AttributeArgumentSyntax> argumentSyntax
                 continue;
 
             var constructorArgumentValues = constructorArguments.Select(
-                (arg, i) => BuildArgumentValue(arg, parameters[i + typeArguments.Count].ParameterType, argumentSyntax[i])
+                (arg, i) => BuildArgumentValue(arg, parameters[i + typeArguments.Count].ParameterType, argumentSyntax[i], symbolAccessor)
             );
             var constructorTypeAndValueArguments = typeArguments.Concat(constructorArgumentValues).ToArray();
             if (!ValidateParameterTypes(constructorTypeAndValueArguments, parameters))
@@ -125,7 +127,12 @@ IReadOnlyList<AttributeArgumentSyntax> argumentSyntax
         );
     }
 
-    private static object? BuildArgumentValue(TypedConstant arg, Type targetType, AttributeArgumentSyntax? syntax)
+    private static object? BuildArgumentValue(
+        TypedConstant arg,
+        Type targetType,
+        AttributeArgumentSyntax? syntax,
+        SymbolAccessor? symbolAccessor
+    )
     {
         return arg.Kind switch
         {
@@ -134,9 +141,9 @@ IReadOnlyList<AttributeArgumentSyntax> argumentSyntax
                 syntax.Expression
             ),
             _ when arg.IsNull => null,
-            _ when targetType == typeof(StringMemberPath) => CreateMemberPath(arg, syntax),
+            _ when targetType == typeof(IMemberPathConfiguration) => CreateMemberPath(arg, syntax, symbolAccessor),
             TypedConstantKind.Enum => GetEnumValue(arg, targetType),
-            TypedConstantKind.Array => BuildArrayValue(arg, targetType),
+            TypedConstantKind.Array => BuildArrayValue(arg, targetType, symbolAccessor),
             TypedConstantKind.Primitive => arg.Value,
             TypedConstantKind.Type when targetType == typeof(ITypeSymbol) => arg.Value,
             _ => throw new ArgumentOutOfRangeException(
@@ -145,12 +152,21 @@ IReadOnlyList<AttributeArgumentSyntax> argumentSyntax
         };
     }
 
-    private static StringMemberPath CreateMemberPath(TypedConstant arg, AttributeArgumentSyntax? syntax)
+    private static IMemberPathConfiguration CreateMemberPath(
+        TypedConstant arg,
+        AttributeArgumentSyntax? syntax,
+        SymbolAccessor? symbolAccessor
+    )
     {
+        if (symbolAccessor == null)
+        {
+            throw new ArgumentNullException(nameof(symbolAccessor), "The symbol accessor cannot be null when resolving member paths");
+        }
+
         if (arg.Kind == TypedConstantKind.Array)
         {
             var values = arg
-                .Values.Select(x => (string?)BuildArgumentValue(x, typeof(string), null))
+                .Values.Select(x => (string?)BuildArgumentValue(x, typeof(string), null, symbolAccessor))
                 .WhereNotNull()
                 .ToImmutableEquatableArray();
             return new StringMemberPath(values);
@@ -166,35 +182,60 @@ is InvocationExpressionSyntax
                 } invocationExpressionSyntax
         )
         {
-            var argMemberPathStr = invocationExpressionSyntax.ArgumentList.Arguments[0].ToFullString();
-
-            // @ prefix opts-in to full nameof
-            if (argMemberPathStr.Length > 0 && argMemberPathStr[0] == FullNameOfPrefix)
-            {
-                var argMemberPath = argMemberPathStr
-                    .TrimStart(FullNameOfPrefix)
-                    .Split(StringMemberPath.MemberAccessSeparator)
-                    .Skip(1)
-                    .ToImmutableEquatableArray();
-                return new StringMemberPath(argMemberPath);
-            }
+            return CreateNameOfMemberPath(invocationExpressionSyntax, symbolAccessor);
         }
 
         if (arg is { Kind: TypedConstantKind.Primitive, Value: string v })
         {
-            return new StringMemberPath(v.Split(StringMemberPath.MemberAccessSeparator).ToImmutableEquatableArray());
+            return new StringMemberPath(v.Split(MemberPathConstants.MemberAccessSeparator).ToImmutableEquatableArray());
         }
 
         throw new InvalidOperationException($"Cannot create {nameof(StringMemberPath)} from {arg.Kind}");
     }
 
-    private static object?[] BuildArrayValue(TypedConstant arg, Type targetType)
+    private static IMemberPathConfiguration CreateNameOfMemberPath(InvocationExpressionSyntax nameofSyntax, SymbolAccessor symbolAccessor)
+    {
+        var argMemberPathStr = nameofSyntax.ArgumentList.Arguments[0].ToFullString();
+
+        // @ prefix opts-in to full nameof
+        var fullNameOf = argMemberPathStr[0] == FullNameOfPrefix;
+
+        var nameOfOperation = symbolAccessor.GetOperation(nameofSyntax) as INameOfOperation;
+        var memberRefOperation = nameOfOperation?.GetFirstChildOperation() as IMemberReferenceOperation;
+        if (memberRefOperation == null)
+        {
+            // fall back to old skip-first-segment approach
+            // to ensure backwards compability.
+            var argMemberPath = argMemberPathStr
+                .TrimStart(FullNameOfPrefix)
+                .Split(MemberPathConstants.MemberAccessSeparator)
+                .Skip(1)
+                .ToImmutableEquatableArray();
+            return new StringMemberPath(argMemberPath);
+        }
+
+        var memberPath = new List<ISymbol>();
+        while (memberRefOperation != null)
+        {
+            memberPath.Add(memberRefOperation.Member);
+            memberRefOperation = memberRefOperation.GetFirstChildOperation() as IMemberReferenceOperation;
+
+            // if not fullNameOf only consider the last member path segment
+            if (!fullNameOf && memberPath.Count > 1)
+                break;
+        }
+
+        memberPath.Reverse();
+        return new SymbolMemberPath(memberPath.ToImmutableEquatableArray());
+    }
+
+    private static object?[] BuildArrayValue(TypedConstant arg, Type targetType, SymbolAccessor? symbolAccessor)
     {
         if (!targetType.IsGenericType || targetType.GetGenericTypeDefinition() != typeof(IReadOnlyCollection<>))
             throw new InvalidOperationException($"{nameof(IReadOnlyCollection<object>)} is the only supported array type");
 
         var elementTargetType = targetType.GetGenericArguments()[0];
-        return arg.Values.Select(x => BuildArgumentValue(x, elementTargetType, null)).ToArray();
+        return arg.Values.Select(x => BuildArgumentValue(x, elementTargetType, null, symbolAccessor)).ToArray();
     }
 
     private static object? GetEnumValue(TypedConstant arg, Type targetType)

src/Riok.Mapperly/Configuration/IMemberPathConfiguration.cs

@@ -0,0 +1,22 @@
+namespace Riok.Mapperly.Configuration;
+
+/// <summary>
+/// A user-configured member path.
+/// </summary>
+public interface IMemberPathConfiguration
+{
+    /// <summary>
+    /// The name of the root member.
+    /// </summary>
+    string RootName { get; }
+
+    /// <summary>
+    /// The full name e.g. A.B.C
+    /// </summary>
+    string FullName { get; }
+
+    /// <summary>
+    /// The number of path segments in this path.
+    /// </summary>
+    int PathCount { get; }
+}

src/Riok.Mapperly/Configuration/MemberMappingConfiguration.cs

@@ -4,12 +4,12 @@
 namespace Riok.Mapperly.Configuration;
 
 [DebuggerDisplay("{Source} => {Target}")]
-public record MemberMappingConfiguration(StringMemberPath Source, StringMemberPath Target) : HasSyntaxReference
+public record MemberMappingConfiguration(IMemberPathConfiguration Source, IMemberPathConfiguration Target) : HasSyntaxReference
 {
     /// <summary>
     /// Used to adapt from <see cref="Abstractions.MapPropertyFromSourceAttribute"/>
     /// </summary>
-    public MemberMappingConfiguration(StringMemberPath Target)
+    public MemberMappingConfiguration(IMemberPathConfiguration Target)
         : this(Source: StringMemberPath.Empty, Target) { }
 
     public string? StringFormat { get; set; }

src/Riok.Mapperly/Configuration/MemberPathConstants.cs

@@ -0,0 +1,7 @@
+namespace Riok.Mapperly.Configuration;
+
+internal static class MemberPathConstants
+{
+    public const char MemberAccessSeparator = '.';
+    public const string MemberAccessSeparatorString = ".";
+}

src/Riok.Mapperly/Configuration/MemberValueMappingConfiguration.cs

@@ -3,12 +3,12 @@
 namespace Riok.Mapperly.Configuration;
 
 [DebuggerDisplay("{Target}: {DescribeValue()}")]
-public record MemberValueMappingConfiguration(StringMemberPath Target, AttributeValue? Value) : HasSyntaxReference
+public record MemberValueMappingConfiguration(IMemberPathConfiguration Target, AttributeValue? Value) : HasSyntaxReference
 {
     /// <summary>
     /// Constructor used by <see cref="AttributeDataAccessor"/>.
     /// </summary>
-    public MemberValueMappingConfiguration(StringMemberPath target)
+    public MemberValueMappingConfiguration(IMemberPathConfiguration target)
         : this(target, null) { }
 
     public string? Use { get; set; }

src/Riok.Mapperly/Configuration/MembersMappingConfiguration.cs

@@ -17,10 +17,10 @@ public IEnumerable<string> GetMembersWithExplicitConfigurations(MappingSourceTar
     {
         var members = sourceTarget switch
         {
-            MappingSourceTarget.Source => ExplicitMappings.Where(x => x.Source.Path.Count > 0).Select(x => x.Source.Path[0]),
+            MappingSourceTarget.Source => ExplicitMappings.Where(x => x.Source.PathCount > 0).Select(x => x.Source.RootName),
             MappingSourceTarget.Target => ExplicitMappings
-                .Select(x => x.Target.Path[0])
-                .Concat(ValueMappings.Select(x => x.Target.Path[0])),
+                .Select(x => x.Target.RootName)
+                .Concat(ValueMappings.Select(x => x.Target.RootName)),
             _ => throw new ArgumentOutOfRangeException(nameof(sourceTarget), sourceTarget, "Neither source or target"),
         };
         return members.Distinct();

src/Riok.Mapperly/Configuration/NestedMembersMappingConfiguration.cs

@@ -1,3 +1,3 @@
 namespace Riok.Mapperly.Configuration;
 
-public record NestedMembersMappingConfiguration(StringMemberPath Source);
+public record NestedMembersMappingConfiguration(IMemberPathConfiguration Source);

src/Riok.Mapperly/Configuration/StringMemberPath.cs

@@ -2,17 +2,16 @@
 
 namespace Riok.Mapperly.Configuration;
 
-public readonly record struct StringMemberPath(ImmutableEquatableArray<string> Path)
+public readonly record struct StringMemberPath(ImmutableEquatableArray<string> Path) : IMemberPathConfiguration
 {
     public static readonly StringMemberPath Empty = new(ImmutableEquatableArray<string>.Empty);
 
     public StringMemberPath(IEnumerable<string> path)
         : this(path.ToImmutableEquatableArray()) { }
 
-    public const char MemberAccessSeparator = '.';
-    private const string MemberAccessSeparatorString = ".";
-
-    public string FullName => string.Join(MemberAccessSeparatorString, Path);
+    public string RootName => Path[0];
+    public string FullName => string.Join(MemberPathConstants.MemberAccessSeparatorString, Path);
+    public int PathCount => Path.Count;
 
     public override string ToString() => FullName;
 

src/Riok.Mapperly/Configuration/SymbolMemberPath.cs

@@ -0,0 +1,21 @@
+using Microsoft.CodeAnalysis;
+using Riok.Mapperly.Helpers;
+
+namespace Riok.Mapperly.Configuration;
+
+/// <summary>
+/// A configured member path consisting of resolved symbols.
+/// </summary>
+/// <param name="Path">The path.</param>
+public record SymbolMemberPath(ImmutableEquatableArray<ISymbol> Path) : IMemberPathConfiguration
+{
+    private string? _fullName;
+
+    public string RootName => Path[0].Name;
+    public string FullName => _fullName ??= string.Join(MemberPathConstants.MemberAccessSeparatorString, Path.Select(x => x.Name));
+    public int PathCount => Path.Count;
+
+    public override string ToString() => FullName;
+
+    public StringMemberPath ToStringMemberPath() => new(Path.Select(x => x.Name));
+}

src/Riok.Mapperly/Descriptors/MappingBodyBuilders/BuilderContext/IgnoredMembersBuilder.cs

@@ -73,7 +73,7 @@ IEnumerable<string> allMembers
 
         foreach (var member in unmatchedMembers)
         {
-            if (member.Contains(StringMemberPath.MemberAccessSeparator, StringComparison.Ordinal))
+            if (member.Contains(MemberPathConstants.MemberAccessSeparator, StringComparison.Ordinal))
             {
                 ctx.ReportDiagnostic(nestedDiagnostic, member, type);
                 continue;

src/Riok.Mapperly/Descriptors/MappingBodyBuilders/BuilderContext/MembersMappingBuilderContext.cs

@@ -269,7 +269,7 @@ private bool TryFindSourcePath(
     {
         if (TryGetMemberConfigs(targetMember.Name, false, out var memberConfigs))
         {
-            var memberConfig = memberConfigs.FirstOrDefault(x => x.Target.Path.Count == 1);
+            var memberConfig = memberConfigs.FirstOrDefault(x => x.Target.PathCount == 1);
             if (memberConfig != null && ResolveMemberConfigSourcePath(memberConfig, out var sourceMember))
             {
                 return new MemberMappingInfo(sourceMember, new NonEmptyMemberPath(BuilderContext.Target, [targetMember]), memberConfig);
@@ -278,7 +278,7 @@ private bool TryFindSourcePath(
 
         if (ignoreCase && TryGetMemberConfigs(targetMember.Name, true, out memberConfigs))
         {
-            var memberConfig = memberConfigs.FirstOrDefault(x => x.Target.Path.Count == 1);
+            var memberConfig = memberConfigs.FirstOrDefault(x => x.Target.PathCount == 1);
             if (memberConfig != null && ResolveMemberConfigSourcePath(memberConfig, out var sourceMember))
             {
                 return new MemberMappingInfo(sourceMember, new NonEmptyMemberPath(BuilderContext.Target, [targetMember]), memberConfig);
@@ -318,7 +318,7 @@ private bool TryGetConfiguredMemberMappingInfo(
     {
         if (TryGetMemberValueConfigs(targetMember.Name, false, out var memberValueConfigs))
         {
-            var memberValueConfig = memberValueConfigs.FirstOrDefault(x => x.Target.Path.Count == 1);
+            var memberValueConfig = memberValueConfigs.FirstOrDefault(x => x.Target.PathCount == 1);
             if (memberValueConfig != null)
             {
                 return new MemberMappingInfo(new NonEmptyMemberPath(BuilderContext.Target, [targetMember]), memberValueConfig);
@@ -327,7 +327,7 @@ private bool TryGetConfiguredMemberMappingInfo(
 
         if (ignoreCase && TryGetMemberValueConfigs(targetMember.Name, true, out memberValueConfigs))
         {
-            var memberValueConfig = memberValueConfigs.FirstOrDefault(x => x.Target.Path.Count == 1);
+            var memberValueConfig = memberValueConfigs.FirstOrDefault(x => x.Target.PathCount == 1);
             if (memberValueConfig != null)
             {
                 return new MemberMappingInfo(new NonEmptyMemberPath(BuilderContext.Target, [targetMember]), memberValueConfig);