[generator] Support varargs arrays in event listener methods (#832)

jpobst · web-flow · commit c925b784e255 · 2021-05-05T18:50:35.000-04:00
Fixes: #817 Assume you have a Java event listener interface which accepts a Java [varargs array][0], e.g.: // Java public interface SomeListener { void onSomeNotification(long a, Object... b); } public class Whatever { public void setSomeListener(SomeListener listener) {…} } then `SomeListener` and `Whatever` are bound as expected: // C# binding public partial interface ISomeListener { void OnSomeNotification(long a, params Object[] b); } public partial class Whatever { public void SetSomeListener(ISomeListener listener) {…} } *and also*, we ["eventify"][1] the listener interface members, wherein the listener interface members become events on the using type, with their `on` prefix removed: public partial class Whatever { public event EventHandler<SomeNotificationEventArgs> SomeNotification {…} } All parameters on the listener method become constructor parameters on the `EventArgs` subclass: public partial class SomeNotificationEventArgs : EventArgs { public SomeNotificationEventArgs(long a, params Object[] b); } Those parameters also become readonly properties: partial class SomeNotificationEventArgs { public long A {get;} } The bug is that when Java varargs arrays are used, the C# `params` keyword remains on the declared `EventArgs` subclass property: partial class SomeNotificationEventArgs { public params Object[] B {get;} } Which results in a CS1519 error: error CS1519: Invalid token 'params' in class, struct, or interface member declaration Fix the CS1519 by removing the extraneous `params` output: partial class SomeNotificationEventArgs { public Object[] B {get;} } [0]: https://docs.oracle.com/javase/1.5.0/docs/guide/language/varargs.html [1]: https://docs.microsoft.com/en-us/xamarin/android/internals/api-design#events-and-listeners
diff --git a/tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/Common/WriteInterfaceEventArgsWithParamArray.txt b/tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/Common/WriteInterfaceEventArgsWithParamArray.txt
@@ -0,0 +1,14 @@
+// event args for com.xamarin.android.MyListener.onDoSomething
+public partial class MyEventArgs : global::System.EventArgs {
+
+	public MyEventArgs (params Java.Lang.Object[] args)
+	{
+		this.args = args;
+	}
+
+	Java.Lang.Object[] args;
+	public Java.Lang.Object[] Args {
+		get { return args; }
+	}
+}
+
diff --git a/tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1-NRT/WriteInterfaceEventArgsWithParamArray.txt b/tests/generator-Tests/Unit-Tests/CodeGeneratorExpectedResults/XAJavaInterop1-NRT/WriteInterfaceEventArgsWithParamArray.txt
@@ -0,0 +1,14 @@
+// event args for com.xamarin.android.MyListener.onDoSomething
+public partial class MyEventArgs : global::System.EventArgs {
+
+	public MyEventArgs (params Java.Lang.Object[]? args)
+	{
+		this.args = args;
+	}
+
+	Java.Lang.Object[]? args;
+	public Java.Lang.Object[]? Args {
+		get { return args; }
+	}
+}
+
diff --git a/tests/generator-Tests/Unit-Tests/CodeGeneratorTests.cs b/tests/generator-Tests/Unit-Tests/CodeGeneratorTests.cs
@@ -1040,6 +1040,32 @@ public void WriteInterfaceEventArgs ()
 			Assert.AreEqual (GetExpected (nameof (WriteInterfaceEventArgs)), writer.ToString ().NormalizeLineEndings ());
 		}
 
+		[Test]
+		public void WriteInterfaceEventArgsWithParamArray ()
+		{
+			var xml = @"<api>
+			  <package name='java.lang' jni-name='java/lang'>
+			    <class abstract='false' deprecated='not deprecated' final='false' name='Object' static='false' visibility='public' jni-signature='Ljava/lang/Object;' />
+			  </package>
+			  <package name='com.xamarin.android' jni-name='com/xamarin/android'>
+			    <interface abstract='true' deprecated='not deprecated' final='false' name='MyListener' static='true' visibility='public' jni-signature='Lcom/xamarin/android/MyListener;'>
+			      <method abstract='true' deprecated='deprecated' final='false' name='onDoSomething' jni-signature='([Ljava/lang/Object;)V' bridge='false' native='false' return='void' jni-return='V' static='false' synchronized='false' synthetic='false' visibility='public'>
+			        <parameter name='args' type='java.lang.Object...' jni-type='[Ljava/lang/Object;'></parameter>
+			      </method>
+			    </interface>
+			  </package>
+			</api>";
+
+			var gens = ParseApiDefinition (xml);
+			var iface = gens.Single (g => g.Name == "IMyListener");
+
+			generator.Context.ContextTypes.Push (iface);
+			generator.WriteInterfaceEventArgs (iface as InterfaceGen, iface.Methods [0], string.Empty);
+			generator.Context.ContextTypes.Pop ();
+
+			Assert.AreEqual (GetExpected (nameof (WriteInterfaceEventArgsWithParamArray)), writer.ToString ().NormalizeLineEndings ());
+		}
+
 		[Test]
 		public void WriteInterfaceEventHandler ()
 		{
diff --git a/tools/generator/Java.Interop.Tools.Generator.CodeGeneration/CodeGenerator.cs b/tools/generator/Java.Interop.Tools.Generator.CodeGeneration/CodeGenerator.cs
@@ -598,10 +598,14 @@ public void WriteInterfaceEventArgs (InterfaceGen @interface, Method m, string i
 						if (p.IsSender)
 							continue;
 						writer.WriteLine ();
-						//var safeTypeName = p.Type.StartsWith ("params ", StringComparison.Ordinal) ? p.Type.Substring ("params ".Length) : p.Type;
-						writer.WriteLine ("{0}\t{1} {2};", indent, opt.GetTypeReferenceName (p), opt.GetSafeIdentifier (p.Name));
+
+						// Remove "params" from things like "global::Java.Lang.Object[]"
+						var type_reference_name = opt.GetTypeReferenceName (p);
+						type_reference_name = type_reference_name.StartsWith ("params ", StringComparison.Ordinal) ? type_reference_name.Substring ("params ".Length) : type_reference_name;
+
+						writer.WriteLine ("{0}\t{1} {2};", indent, type_reference_name, opt.GetSafeIdentifier (p.Name));
 						// AbsListView.IMultiChoiceModeListener.onItemCheckedStateChanged() hit this strict name check, at parameter "@checked".
-						writer.WriteLine ("{0}\tpublic {1} {2} {{", indent, opt.GetTypeReferenceName (p), p.PropertyName);
+						writer.WriteLine ("{0}\tpublic {1} {2} {{", indent, type_reference_name, p.PropertyName);
 						writer.WriteLine ("{0}\t\tget {{ return {1}; }}", indent, opt.GetSafeIdentifier (p.Name));
 						writer.WriteLine ("{0}\t}}", indent);
 					}
