InteropGen: append hash to end of function names based on signature, allows us to support overloaded methods, multiple ctors, etc.

Author: xezno

Source/MochaTool.InteropGen/CodeGen/ManagedCodeGenerator.cs

@@ -102,6 +102,7 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 			var method = c.Methods[i];
 			var returnType = Utils.GetManagedType( method.ReturnType );
 			var name = method.Name;
+			var hash = method.Hash;
 
 			var returnsPointer = Utils.IsPointer( method.ReturnType ) && !method.IsConstructor && !method.IsDestructor;
 
@@ -129,7 +130,7 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 			// any parameters. The return type is the last type argument passed to
 			// the delegate.
 			//
-			decls[i] = $"private static {delegateSignature} _{name} = ({delegateSignature})Mocha.Common.Global.UnmanagedArgs.__{c.Name}_{name}MethodPtr;";
+			decls[i] = $"private static {delegateSignature} _{hash} = ({delegateSignature})Mocha.Common.Global.UnmanagedArgs.__{c.Name}_{hash};";
 		}
 
 		//
@@ -148,17 +149,16 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 		writer.WriteLine();
 
 		// Ctor
-		if ( c.Methods.Any( x => x.IsConstructor ) )
+		foreach ( var ctor in c.Methods.Where( x => x.IsConstructor ) )
 		{
-			var ctor = c.Methods.First( x => x.IsConstructor );
 			var managedCtorArgs = string.Join( ", ", ctor.Parameters.Select( x => $"{Utils.GetManagedType( x.Type )} {x.Name}" ) );
 
 			writer.WriteLine( $"public {c.Name}( {managedCtorArgs} )" );
 			writer.WriteLine( "{" );
 			writer.Indent++;
 
 			var ctorCallArgs = string.Join( ", ", ctor.Parameters.Select( x => x.Name ) );
-			writer.WriteLine( $"this.NativePtr = this.Ctor( {ctorCallArgs} );" );
+			writer.WriteLine( $"this.NativePtr = this.{ctor.Name}( {ctorCallArgs} );" );
 
 			writer.Indent--;
 			writer.WriteLine( "}" );
@@ -175,6 +175,7 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 			// Call parameters as comma-separated string
 			var managedCallParams = string.Join( ", ", method.Parameters.Select( x => $"{Utils.GetManagedType( x.Type )} {x.Name}" ) );
 			var name = method.Name;
+			var hash = method.Hash;
 
 			// We return a pointer to the created object if it's a ctor/dtor, but otherwise we'll do auto-conversions to our managed types
 			var returnType = (method.IsConstructor || method.IsDestructor) ? "IntPtr" : Utils.GetManagedType( method.ReturnType );
@@ -188,12 +189,12 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 				accessLevel += " static";
 
 			// Write function signature
-			writer.WriteLine( $"{accessLevel} {returnType} {name}( {managedCallParams} ) " );
+			writer.WriteLine( $"{accessLevel} {returnType} {method.Name}( {managedCallParams} ) " );
 			writer.WriteLine( "{" );
 			writer.Indent++;
 
 			// Spin up a MemoryContext instance
-			writer.WriteLine( $"using var ctx = new MemoryContext( \"{c.Name}.{name}\" );" );
+			writer.WriteLine( $"using var ctx = new MemoryContext( \"{c.Name}.{method.Name}\" );" );
 
 			//
 			// Gather function body
@@ -213,7 +214,7 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 			if ( returnsPointer )
 			{
 				// If we want to return a pointer:
-				writer.WriteLine( $"var ptr = _{name}( {functionCallArgs} );" );
+				writer.WriteLine( $"var ptr = _{hash}( {functionCallArgs} );" );
 				writer.WriteLine( $"var obj = FormatterServices.GetUninitializedObject( typeof( {returnType} ) ) as {returnType};" );
 				writer.WriteLine( $"obj.NativePtr = ptr;" );
 				writer.WriteLine( $"return obj;" );
@@ -229,7 +230,7 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 					writer.Write( "ctx.GetString( " );
 
 				// Call the function..
-				writer.Write( $"_{name}( {functionCallArgs} )" );
+				writer.Write( $"_{hash}( {functionCallArgs} )" );
 
 				// Finish string
 				if ( returnType == "string" )
@@ -300,7 +301,7 @@ private static void GenerateNamespaceCode( IndentedTextWriter writer, Namespace
 			// any parameters. The return type is the last type argument passed to
 			// the delegate.
 			//
-			decls[i] = $"private static {delegateSignature} _{name} = ({delegateSignature})Mocha.Common.Global.UnmanagedArgs.__{ns.Name}_{name}MethodPtr;";
+			decls[i] = $"private static {delegateSignature} _{name} = ({delegateSignature})Mocha.Common.Global.UnmanagedArgs.__{ns.Name}_{method.Hash};";
 		}
 
 		//

Source/MochaTool.InteropGen/CodeGen/NativeCodeGenerator.cs

@@ -79,7 +79,7 @@ private static void GenerateClassCode( IndentedTextWriter writer, Class c )
 				return $"{x.Type} {x.Name}";
 			} ) );
 
-			var signature = $"extern \"C\" inline {method.ReturnType} __{c.Name}_{method.Name}( {argStr} )";
+			var signature = $"extern \"C\" inline {method.ReturnType} __{c.Name}_{method.Hash}( {argStr} )";
 			var body = "";
 			var parameters = string.Join( ", ", method.Parameters.Select( x => x.Name ) );
 
@@ -129,7 +129,7 @@ private static void GenerateNamespaceCode( IndentedTextWriter writer, Namespace
 				return $"{x.Type} {x.Name}";
 			} ) );
 
-			var signature = $"extern \"C\" inline {method.ReturnType} __{ns.Name}_{method.Name}( {argStr} )";
+			var signature = $"extern \"C\" inline {method.ReturnType} __{ns.Name}_{method.Hash}( {argStr} )";
 			var body = "";
 			var parameters = string.Join( ", ", method.Parameters.Select( x => x.Name ) );
 

Source/MochaTool.InteropGen/Parsing/ContainerBuilder.cs

@@ -11,6 +11,7 @@ internal sealed class ContainerBuilder
 	/// The type of container that is being built.
 	/// </summary>
 	internal ContainerType Type { get; }
+
 	/// <summary>
 	/// The name of the container.
 	/// </summary>
@@ -24,6 +25,29 @@ internal sealed class ContainerBuilder
 	private readonly ImmutableArray<Variable>.Builder fields;
 	private readonly ImmutableArray<Method>.Builder methods;
 
+	/// <summary>
+	/// Does a method with this name already exist in this container?
+	/// </summary>
+	public bool HasMethod( string name ) => methods.Any( x => x.Name == name );
+
+	/// <summary>
+	/// Finds an available name for a function. If one isn't available, follows
+	/// the function name up with a counter.
+	/// </summary>
+	public string FindFreeName( string desiredName )
+	{
+		var name = desiredName;
+		var index = 0;
+
+		while ( HasMethod( name ) )
+		{
+			index++;
+			name = $"{desiredName}{index}";
+		}
+
+		return desiredName;
+	}
+
 	/// <summary>
 	/// Initializes a new instance of <see cref="ContainerBuilder"/>.
 	/// </summary>

Source/MochaTool.InteropGen/Parsing/Method.cs

@@ -11,6 +11,7 @@ internal sealed class Method : IUnit
 	/// The name of the method.
 	/// </summary>
 	public string Name { get; }
+
 	/// <summary>
 	/// The literal string containing the return type of the method.
 	/// </summary>
@@ -20,10 +21,12 @@ internal sealed class Method : IUnit
 	/// Whether or not the method is a constructor.
 	/// </summary>
 	internal bool IsConstructor { get; } = false;
+
 	/// <summary>
 	/// Whether or not the method is a destructor.
 	/// </summary>
 	internal bool IsDestructor { get; } = false;
+
 	/// <summary>
 	/// Whether or not the method is static.
 	/// </summary>
@@ -34,6 +37,11 @@ internal sealed class Method : IUnit
 	/// </summary>
 	internal ImmutableArray<Variable> Parameters { get; }
 
+	/// <summary>
+	/// A hash representing the signature for this method.
+	/// </summary>
+	public string Hash { get; }
+
 	/// <summary>
 	/// Initializes a new instance of <see cref="Method"/>.
 	/// </summary>
@@ -53,6 +61,33 @@ private Method( string name, string returnType, bool isConstructor, bool isDestr
 		IsStatic = isStatic;
 
 		Parameters = parameters;
+
+		Hash = $"{Name}{ComputeHash()}";
+	}
+
+	private string ComputeHash()
+	{
+		//
+		// alex: We're taking an MD5 representation of the function signature and then truncating
+		// it to 8 characters. Our chances of a collision are "high" (~1 in 4,294,967,296) compared
+		// to other crypto-secure representations (e.g. SHA) but we're not too bothered about that
+		// here. Chances are we'll have 2 or 3 functions that share a name (thru method overloading).
+		//
+
+		var returnType = ReturnType;
+		var name = Name;
+		var parameters = string.Join( ",", Parameters.Select( x => $"{x.Type}{x.Name}" ) );
+
+		var signature = $"{returnType}{name}{parameters}";
+
+		// Use input string to calculate MD5 hash
+		using ( System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create() )
+		{
+			byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes( signature );
+			byte[] hashBytes = md5.ComputeHash( inputBytes );
+
+			return Convert.ToHexString( hashBytes )[..8];
+		}
 	}
 
 	/// <summary>

Source/MochaTool.InteropGen/Parsing/Parser.cs

@@ -135,7 +135,7 @@ private static unsafe CXChildVisitResult VisitMethod( in CXCursor cursor, Contai
 		// We're traversing a constructor.
 		if ( cursor.Kind == CXCursorKind.CXCursor_Constructor )
 		{
-			name = "Ctor";
+			name = currentContainer.FindFreeName( "Ctor" );
 			returnType = currentContainer.Name + '*';
 			isStatic = false;
 			isConstructor = true;
@@ -144,7 +144,7 @@ private static unsafe CXChildVisitResult VisitMethod( in CXCursor cursor, Contai
 		// We're traversing a destructor.
 		else if ( cursor.Kind == CXCursorKind.CXCursor_Destructor )
 		{
-			name = "DeCtor";
+			name = currentContainer.FindFreeName( "Dtor" );
 			returnType = '~' + currentContainer.Name;
 			isStatic = false;
 			isConstructor = false;

Source/MochaTool.InteropGen/Program.cs

@@ -119,7 +119,7 @@ private static async Task WriteManagedStructAsync( string baseDir, IEnumerable<(
 
 		managedStructWriter.WriteLine( "public IntPtr __Root;" );
 
-		var managedStructBody = string.Join( "\r\n\t", methods.Select( x => $"public IntPtr __{x.Name}_{x.method.Name}MethodPtr;" ) );
+		var managedStructBody = string.Join( "\r\n\t", methods.Select( x => $"public IntPtr __{x.Name}_{x.method.Hash};" ) );
 		managedStructWriter.Write( managedStructBody );
 		managedStructWriter.WriteLine();
 
@@ -151,7 +151,7 @@ private static async Task WriteNativeStructAsync( string baseDir, IEnumerable<(s
 
 		nativeStructWriter.WriteLine( "void* __Root;" );
 
-		var nativeStructBody = string.Join( "\r\n\t", methods.Select( x => $"void* __{x.Name}_{x.method.Name}MethodPtr;" ) );
+		var nativeStructBody = string.Join( "\r\n\t", methods.Select( x => $"void* __{x.Name}_{x.method.Hash};" ) );
 		nativeStructWriter.Write( nativeStructBody );
 		nativeStructWriter.WriteLine();
 
@@ -165,7 +165,7 @@ private static async Task WriteNativeStructAsync( string baseDir, IEnumerable<(s
 
 		nativeStructWriter.WriteLine( "Root::GetInstance()," );
 
-		nativeStructBody = string.Join( ",\r\n\t", methods.Select( x => $"(void*)__{x.Name}_{x.method.Name}" ) );
+		nativeStructBody = string.Join( ",\r\n\t", methods.Select( x => $"(void*)__{x.Name}_{x.method.Hash}" ) );
 		nativeStructWriter.Write( nativeStructBody );
 		nativeStructWriter.WriteLine();