Convert class bounded type parameters, close #125

Author: javiertuya

JavaToCSharp.Tests/ConvertTypeTests.cs

@@ -113,4 +113,35 @@ public void ConvertTypeSyntax_GivenMismatchedRank_ShouldThrowException()
 
         Assert.Throws<ArgumentException>(() => TypeHelper.ConvertTypeSyntax(type, 1));
     }
+
+    [Theory]
+    [InlineData("GenericClass<T>", "GenericClass<T>")]
+    [InlineData("GenericClass<T extends BoundType<T>>", "GenericClass<T>\n    where T : BoundType<T>")]
+    [InlineData("GenericClass<T extends BoundType>", "GenericClass<T>\n    where T : BoundType")]
+
+    [InlineData("GenericClass<T, U>", "GenericClass<T, U>")]
+    [InlineData("GenericClass<T, U extends BoundType<U>>", "GenericClass<T, U>\n    where U : BoundType<U>")]
+    [InlineData("GenericClass<T extends BoundType1<T>, U extends BoundType2<U>>", "GenericClass<T, U>\n    where T : BoundType1<T> where U : BoundType2<U>")]
+
+    [InlineData("GenericClass<T extends BoundType1<T> & BoundType2<T>>", "GenericClass<T>\n    where T : BoundType1<T>, BoundType2<T>")]
+    public void ConvertClassTypeBoundedParameters(string javaClass, string csharpClass)
+    {
+        string javaCode = $$"""
+                                public class {{javaClass}} { }
+                                """;
+        var options = new JavaConversionOptions
+        {
+            IncludeUsings = false,
+            IncludeNamespace = false,
+        };
+        var parsed = JavaToCSharpConverter.ConvertText(javaCode, options) ?? "";
+        string expected = $$"""
+                                public class {{csharpClass}}
+                                {
+                                }
+
+                                """;
+
+        Assert.Equal(expected.ReplaceLineEndings(), parsed.ReplaceLineEndings());
+    }
 }

JavaToCSharp/Declarations/ClassOrInterfaceDeclarationVisitor.cs

@@ -128,6 +128,7 @@ public static ClassDeclarationSyntax VisitClassDeclaration(ConversionContext con
         {
             classSyntax = classSyntax.AddTypeParameterListParameters(typeParams
                     .Select(i => SyntaxFactory.TypeParameter(i.getNameAsString())).ToArray());
+            classSyntax = classSyntax.AddConstraintClauses(TypeHelper.GetTypeParameterListConstraints(typeParams).ToArray());
         }
 
         var mods = classDecl.getModifiers().ToModifierKeywordSet();

JavaToCSharp/TypeHelper.cs

@@ -194,6 +194,31 @@ private static SeparatedSyntaxList<ArgumentSyntax> GetSeparatedListFromArguments
         return SyntaxFactory.SeparatedList(argSyntaxes, separators);
     }
 
+    /// <summary>
+    /// Returns the list of C# type parameter constraints that must be added to a class syntax
+    /// to convert the java bounded type parameters of a class declaration.
+    /// e.g. to convert <![CDATA[ <T extends Clazz<T>> ]]> into <![CDATA[ <T> where T : Clazz<T> ]]>
+    /// </summary>
+    public static IEnumerable<TypeParameterConstraintClauseSyntax> GetTypeParameterListConstraints(List<TypeParameter> typeParams)
+    {
+        var typeParameterConstraints = new List<TypeParameterConstraintClauseSyntax>();
+        foreach (TypeParameter typeParam in typeParams)
+        {
+            if (typeParam.getTypeBound().size() > 0)
+            {
+                var typeConstraintsSyntax = new SeparatedSyntaxList<TypeParameterConstraintSyntax>();
+                foreach (ClassOrInterfaceType bound in typeParam.getTypeBound())
+                    typeConstraintsSyntax = typeConstraintsSyntax.Add(SyntaxFactory.TypeConstraint(SyntaxFactory.ParseTypeName(bound.asString())));
+
+                var typeIdentifier = SyntaxFactory.IdentifierName(typeParam.getName().asString());
+                var parameterConstraintClauseSyntax = SyntaxFactory.TypeParameterConstraintClause(typeIdentifier, typeConstraintsSyntax);
+
+                typeParameterConstraints.Add(parameterConstraintClauseSyntax);
+            }
+        }
+        return typeParameterConstraints;
+    }
+
     /// <summary>
     /// Transforms method calls into property and indexer accesses where appropriate.
     /// </summary>