fix: consider a type as immutable only if it is a read only type or a…

… string (#9)
riok · Feb 15, 2022 · 93d8eec · 93d8eec
1 parent 31439ce
commit 93d8eec
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Showing 10 changed files with 72 additions and 29 deletions.
diff --git a/src/Riok.Mapperly/Descriptors/DescriptorBuilder.cs b/src/Riok.Mapperly/Descriptors/DescriptorBuilder.cs
@@ -15,7 +15,7 @@ public class DescriptorBuilder
     private static readonly IReadOnlyCollection<MappingBuilder> _mappingBuilders = new MappingBuilder[]
     {
         SpecialTypeMappingBuilder.TryBuildMapping,
-        ValueTypeMappingBuilder.TryBuildMapping,
+        ImmutableTypeMappingBuilder.TryBuildMapping,
         DictionaryMappingBuilder.TryBuildMapping,
         EnumerableMappingBuilder.TryBuildMapping,
         ImplicitCastMappingBuilder.TryBuildMapping,

diff --git a/src/Riok.Mapperly/Descriptors/MappingBuilder/ExplicitCastMappingBuilder.cs b/src/Riok.Mapperly/Descriptors/MappingBuilder/ExplicitCastMappingBuilder.cs
@@ -1,12 +1,16 @@
 using Microsoft.CodeAnalysis.CSharp;
 using Riok.Mapperly.Descriptors.TypeMappings;
+using Riok.Mapperly.Helpers;
 
 namespace Riok.Mapperly.Descriptors.MappingBuilder;
 
 public static class ExplicitCastMappingBuilder
 {
     public static CastMapping? TryBuildMapping(MappingBuilderContext ctx)
     {
+        if (!ctx.Source.IsImmutable() && !ctx.Target.IsImmutable())
+            return null;
+
         var conversion = ctx.Compilation.ClassifyConversion(ctx.Source, ctx.Target);
 
         // only allow user defined explicit reference conversions

diff --git a/...MappingBuilder/ValueTypeMappingBuilder.cs → ...ingBuilder/ImmutableTypeMappingBuilder.cs b/...MappingBuilder/ValueTypeMappingBuilder.cs → ...ingBuilder/ImmutableTypeMappingBuilder.cs
@@ -1,13 +1,14 @@
 using Microsoft.CodeAnalysis;
 using Riok.Mapperly.Descriptors.TypeMappings;
+using Riok.Mapperly.Helpers;
 
 namespace Riok.Mapperly.Descriptors.MappingBuilder;
 
-public static class ValueTypeMappingBuilder
+public static class ImmutableTypeMappingBuilder
 {
     public static TypeMapping? TryBuildMapping(MappingBuilderContext ctx)
     {
-        return SymbolEqualityComparer.Default.Equals(ctx.Source, ctx.Target) && ctx.Source.IsValueType
+        return SymbolEqualityComparer.IncludeNullability.Equals(ctx.Source, ctx.Target) && ctx.Source.IsImmutable()
             ? new DirectAssignmentMapping(ctx.Source)
             : null;
     }

diff --git a/src/Riok.Mapperly/Descriptors/MappingBuilder/ImplicitCastMappingBuilder.cs b/src/Riok.Mapperly/Descriptors/MappingBuilder/ImplicitCastMappingBuilder.cs
@@ -1,12 +1,16 @@
 using Microsoft.CodeAnalysis.CSharp;
 using Riok.Mapperly.Descriptors.TypeMappings;
+using Riok.Mapperly.Helpers;
 
 namespace Riok.Mapperly.Descriptors.MappingBuilder;
 
 public static class ImplicitCastMappingBuilder
 {
     public static CastMapping? TryBuildMapping(MappingBuilderContext ctx)
     {
+        if (!ctx.Source.IsImmutable() && !ctx.Target.IsImmutable())
+            return null;
+
         var conversion = ctx.Compilation.ClassifyConversion(ctx.Source, ctx.Target);
         return conversion.IsImplicit
             ? new CastMapping(ctx.Source, ctx.Target)

diff --git a/src/Riok.Mapperly/Descriptors/MappingBuilder/SpecialTypeMappingBuilder.cs b/src/Riok.Mapperly/Descriptors/MappingBuilder/SpecialTypeMappingBuilder.cs
@@ -10,7 +10,6 @@ public static class SpecialTypeMappingBuilder
         return ctx.Target.SpecialType switch
         {
             SpecialType.System_Object => new CastMapping(ctx.Source, ctx.Target),
-            SpecialType.System_String when ctx.Source.SpecialType == SpecialType.System_String => new DirectAssignmentMapping(ctx.Source),
             _ => null,
         };
     }

diff --git a/src/Riok.Mapperly/Helpers/SymbolExtensions.cs b/src/Riok.Mapperly/Helpers/SymbolExtensions.cs
@@ -8,6 +8,9 @@ internal static class SymbolExtensions
     internal static bool HasAttribute(this ISymbol symbol, INamedTypeSymbol attributeSymbol)
         => symbol.GetAttributes().Any(a => SymbolEqualityComparer.Default.Equals(a.AttributeClass, attributeSymbol));
 
+    internal static bool IsImmutable(this ISymbol symbol)
+        => symbol is INamedTypeSymbol namedSymbol && (namedSymbol.IsReadOnly || namedSymbol.SpecialType == SpecialType.System_String);
+
     internal static bool IsAccessible(this ISymbol symbol)
         => symbol.DeclaredAccessibility.HasFlag(Accessibility.Protected)
             || symbol.DeclaredAccessibility.HasFlag(Accessibility.Internal)

diff --git a/test/Riok.Mapperly.Tests/Mapping/ImmutableTypeTest.cs b/test/Riok.Mapperly.Tests/Mapping/ImmutableTypeTest.cs
@@ -0,0 +1,27 @@
+namespace Riok.Mapperly.Tests.Mapping;
+
+public class ImmutableTypeTest
+{
+    [Fact]
+    public void StringToString()
+    {
+        var source = TestSourceBuilder.Mapping(
+            "string",
+            "string");
+        TestHelper.GenerateSingleMapperMethodBody(source)
+            .Should()
+            .Be("return source;");
+    }
+
+    [Fact]
+    public void ReadOnlyStructToSameStruct()
+    {
+        var source = TestSourceBuilder.Mapping(
+            "A",
+            "A",
+            "readonly struct A {}");
+        TestHelper.GenerateSingleMapperMethodBody(source)
+            .Should()
+            .Be("return source;");
+    }
+}
diff --git a/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyTest.cs b/test/Riok.Mapperly.Tests/Mapping/ObjectPropertyTest.cs
@@ -19,6 +19,34 @@ public void OneSimpleProperty()
     return target;".ReplaceLineEndings());
     }
 
+    [Fact]
+    public void SameType()
+    {
+        var source = TestSourceBuilder.Mapping(
+            "A",
+            "A",
+            "class A { public string StringValue { get; set; } }");
+
+        TestHelper.GenerateSingleMapperMethodBody(source)
+            .Should()
+            .Be(@"var target = new A();
+    target.StringValue = source.StringValue;
+    return target;".ReplaceLineEndings());
+    }
+
+    [Fact]
+    public void CustomRefStructToSameCustomStruct()
+    {
+        var source = TestSourceBuilder.Mapping(
+            "A",
+            "A",
+            "ref struct A {}");
+        TestHelper.GenerateSingleMapperMethodBody(source)
+            .Should()
+            .Be(@"var target = new A();
+    return target;");
+    }
+
     [Fact]
     public void StringToIntProperty()
     {

diff --git a/test/Riok.Mapperly.Tests/Mapping/SpeicalTypeTest.cs b/test/Riok.Mapperly.Tests/Mapping/SpeicalTypeTest.cs
@@ -47,15 +47,4 @@ public void CustomStructToObject()
             .Should()
             .Be("return (object)source;");
     }
-
-    [Fact]
-    public void StringToString()
-    {
-        var source = TestSourceBuilder.Mapping(
-            "string",
-            "string");
-        TestHelper.GenerateSingleMapperMethodBody(source)
-            .Should()
-            .Be("return source;");
-    }
 }
diff --git a/test/Riok.Mapperly.Tests/Mapping/ValueTypeTest.cs b/test/Riok.Mapperly.Tests/Mapping/ValueTypeTest.cs
@@ -3,12 +3,12 @@ namespace Riok.Mapperly.Tests.Mapping;
 public class ValueTypeTest
 {
     [Fact]
-    public void CustomStructToSameCustomStruct()
+    public void CustomReadOnlyStructToSameCustomReadOnlyStruct()
     {
         var source = TestSourceBuilder.Mapping(
             "A",
             "A",
-            "struct A {}");
+            "readonly struct A {}");
         TestHelper.GenerateSingleMapperMethodBody(source)
             .Should()
             .Be("return source;");
@@ -26,18 +26,6 @@ public void CustomReadOnlyStructToSameCustomStruct()
             .Be("return source;");
     }
 
-    [Fact]
-    public void CustomRefStructToSameCustomStruct()
-    {
-        var source = TestSourceBuilder.Mapping(
-            "A",
-            "A",
-            "ref struct A {}");
-        TestHelper.GenerateSingleMapperMethodBody(source)
-            .Should()
-            .Be("return source;");
-    }
-
     [Fact]
     public void StructToSameStruct()
     {