[generator] refactoring for methods (#298)

In the same fashion that 7a96efe refactored fields, this commit aims
at refactoring methods. I also added various unit tests to add
coverage around the new `TestMethod` support type.

Refactoring in generator:

  - Dropped the method "support" classes in favor of extension
    methods from `ManagedExtensions` and `XmlExtensions`. These
    existed due to C# single-inheritance getting in the way of the
    relationship between methods, properties, constructors, etc.
  - Moved methods from `Method` and `MethodBase` to `CodeGenerator`
    and renamed them from `Generate*` to `WriteMethod*`. I tried to
    not modify the code in these methods other than to add a
    parameter for the incoming method.
  - Output of generator *should* remain the same.
  - `*Method` classes are now much closer to POCOs

Other changes:

  - Dropped usage of `ContextTypes` stack in
    `XamarinAndroidCodeGenerator`
  - Added a base test class for `JavaInteropCodeGeneratorTests` and
    `XamarinAndroidCodeGeneratorTests` because there were several
    tests that were completely identical (due to `CodeGenerator` base
    class)
  - Changed `StreamWriter` to `TextWriter` as needed
  - Now up to 88 tests! Most new ones are ~1ms

Future plans (trying to keep this commit of reasonable size):

  - The `CodeGenerator` base class is starting to get large. As
    refactoring continues, I would like to make a class for
    `FieldGenerator`, `MethodGenerator`, etc. and `CodeGenerator`
    would get properties named `Fields` and `Methods` that would
    return these child generator classes
  - This is exactly what @grendello did with his [prototype][0], so
    we should adopt this improvement.

[0]: https://github.com/grendello/JavaBindingGenerator/blob/fb8864d1842bdf0b8d45eb04b89ef2bd57de0014/src/Java.Interop.Bindings/Compiler/MethodCodeGenerator.cs

Author: jonathanpeppers

tools/generator/ClassGen.cs

@@ -15,15 +15,7 @@
 using System.Xml.Linq;
 
 namespace MonoDroid.Generation {
-#if HAVE_CECIL
-	static class ManagedExtensions
-	{
-		public static string FullNameCorrected (this TypeReference t)
-		{
-			return t.FullName.Replace ('/', '.');
-		}
-	}
-	
+#if HAVE_CECIL	
 	public class ManagedClassGen : ClassGen {
 		TypeDefinition t;
 		TypeReference nominal_base_type;
@@ -352,9 +344,9 @@ void GenMethods (StreamWriter sw, string indent, CodeGenerationOptions opt)
 				bool virt = m.IsVirtual;
 				m.IsVirtual = !IsFinal && virt;
 				if (m.IsAbstract && !m.IsInterfaceDefaultMethodOverride && !m.IsInterfaceDefaultMethod)
-					m.GenerateAbstractDeclaration (sw, indent, opt, null, this);
+					opt.CodeGenerator.WriteMethodAbstractDeclaration (m, sw, indent, opt, null, this);
 				else
-					m.Generate (sw, indent, opt, this, true);
+					opt.CodeGenerator.WriteMethod (m, sw, indent, opt, this, true);
 				opt.ContextGeneratedMethods.Add (m);
 				m.IsVirtual = virt;
 			}
@@ -497,7 +489,7 @@ public override void Generate (StreamWriter sw, string indent, CodeGenerationOpt
 							if (m.IsInterfaceDefaultMethod || m.IsStatic)
 								continue;
 							if (m.IsGeneric)
-								m.GenerateExplicitIface (sw, indent + "\t", opt, gs);
+								opt.CodeGenerator.WriteMethodExplicitIface (m, sw, indent + "\t", opt, gs);
 						}
 
 						var adapter = gs.Gen.AssemblyQualifiedName + "Invoker";
@@ -631,11 +623,11 @@ void GenerateInvoker (StreamWriter sw, IEnumerable<Method> methods, string inden
 					continue;
 				if (IsExplicitlyImplementedMethod (sig)) {
 					// sw.WriteLine ("// This invoker explicitly implements this method");
-					m.GenerateExplicitInterfaceInvoker (sw, indent, opt, gen);
+					opt.CodeGenerator.WriteMethodExplicitInterfaceInvoker (m, sw, indent, opt, gen);
 				} else {
 					// sw.WriteLine ("// This invoker overrides {0} method", gen.FullName);
 					m.IsOverride = true;
-					m.Generate (sw, indent, opt, this, false);
+					opt.CodeGenerator.WriteMethod (m, sw, indent, opt, this, false);
 					m.IsOverride = false;
 				}
 			}

tools/generator/CodeGenerator.cs

@@ -15,14 +15,10 @@ public class ManagedCtor : Ctor {
 		bool is_acw;
 
 		public ManagedCtor (GenBase declaringType, MethodDefinition m)
-			: this (declaringType, m, new ManagedMethodBaseSupport (m))
-		{
-		}
-		
-		ManagedCtor (GenBase declaringType, MethodDefinition m, ManagedMethodBaseSupport support)
-			: base (declaringType, support)
+			: base (declaringType)
 		{
 			this.m = m;
+			GenericArguments = m.GenericArguments ();
 			name = m.Name;
 			// If 'elem' is a constructor for a non-static nested type, then
 			// the type of the containing class must be inserted as the first
@@ -31,7 +27,7 @@ public ManagedCtor (GenBase declaringType, MethodDefinition m)
 				Parameters.AddFirst (Parameter.FromManagedType (m.DeclaringType.DeclaringType, DeclaringType.JavaName));
 			var regatt = m.CustomAttributes.FirstOrDefault (a => a.AttributeType.FullName == "Android.Runtime.RegisterAttribute");
 			is_acw = regatt != null;
-			foreach (var p in support.GetParameters (regatt))
+			foreach (var p in m.GetParameters (regatt))
 				Parameters.Add (p);
 		}
 
@@ -52,17 +48,26 @@ public override string Name {
 		public override string CustomAttributes {
 			get { return null; }
 		}
+
+		public override string AssemblyName => m.DeclaringType.Module.Assembly.FullName;
+
+		public override string Visibility => m.Visibility ();
+
+		public override string Deprecated => m.Deprecated ();
 	}
 #endif  // HAVE_CECIL
 
 	public class XmlCtor : Ctor {
+		XElement elem;
 		string name;
 		bool nonStaticNestedType;
 		bool missing_enclosing_class;
 		string custom_attributes;
 
-		public XmlCtor (GenBase declaringType, XElement elem) : base (declaringType, new XmlMethodBaseSupport (elem))
+		public XmlCtor (GenBase declaringType, XElement elem) : base (declaringType)
 		{
+			this.elem = elem;
+			GenericArguments = elem.GenericArguments ();
 			name = elem.XGetAttribute ("name");
 			int idx = name.LastIndexOf ('.');
 			if (idx > 0)
@@ -125,12 +130,16 @@ protected override bool OnValidate (CodeGenerationOptions opt, GenericParameterD
 		public override string CustomAttributes {
 			get { return custom_attributes; }
 		}
+
+		public override string Deprecated => elem.Deprecated ();
+
+		public override string Visibility => elem.Visibility ();
 	}
 
 	public abstract class Ctor : MethodBase {
 
-		protected Ctor (GenBase declaringType, IMethodBaseSupport support)
-			: base (declaringType, support)
+		protected Ctor (GenBase declaringType)
+			: base (declaringType)
 		{
 		}
 

tools/generator/Ctor.cs

@@ -200,15 +200,15 @@ void GenMethods (StreamWriter sw, string indent, CodeGenerationOptions opt)
 			foreach (Method m in Methods.Where (m => !m.IsStatic)) {
 				if (m.Name == Name || ContainsProperty (m.Name, true))
 					m.Name = "Invoke" + m.Name;
-				m.GenerateDeclaration (sw, indent, opt, this, AssemblyQualifiedName + "Invoker");
+				opt.CodeGenerator.WriteMethodDeclaration (m, sw, indent, opt, this, AssemblyQualifiedName + "Invoker");
 			}
 		}
 
 		void GenExtensionMethods (StreamWriter sw, string indent, CodeGenerationOptions opt)
 		{
 			foreach (Method m in Methods.Where (m => !m.IsStatic)) {
-				m.GenerateExtensionOverload (sw, indent, opt, FullName);
-				m.GenerateExtensionAsyncWrapper (sw, indent, opt, FullName);
+				opt.CodeGenerator.WriteMethodExtensionOverload (m, sw, indent, opt, FullName);
+				opt.CodeGenerator.WriteMethodExtensionAsyncWrapper (m, sw, indent, opt, FullName);
 			}
 		}
 
@@ -288,7 +288,7 @@ void GenerateInvoker (StreamWriter sw, IEnumerable<Method> methods, string inden
 				if (members.Contains (sig))
 					continue;
 				members.Add (sig);
-				m.GenerateInvoker (sw, indent, opt, this);
+				opt.CodeGenerator.WriteMethodInvoker (m, sw, indent, opt, this);
 			}
 		}
 
@@ -632,9 +632,9 @@ public void GenerateAbstractMembers (ClassGen gen, StreamWriter sw, string inden
 				if (mapped)
 					continue;
 				if (gen.ExplicitlyImplementedInterfaceMethods.Contains (sig))
-					m.GenerateExplicitInterfaceImplementation (sw, indent, opt, this);
+					opt.CodeGenerator.WriteMethodExplicitInterfaceImplementation (m, sw, indent, opt, this);
 				else
-					m.GenerateAbstractDeclaration (sw, indent, opt, this, gen);
+					opt.CodeGenerator.WriteMethodAbstractDeclaration (m, sw, indent, opt, this, gen);
 				opt.ContextGeneratedMethods.Add (m); 
 			}
 			foreach (Property prop in Properties.Where (p => !p.Getter.IsStatic)) {
@@ -714,7 +714,7 @@ public override void Generate (StreamWriter sw, string indent, CodeGenerationOpt
 				}
 
 				foreach (var m in Methods.Where (m => m.IsStatic))
-					m.Generate (sw, indent + "\t", opt, this, true);
+					opt.CodeGenerator.WriteMethod (m, sw, indent + "\t", opt, this, true);
 
 				if (needsClassRef) {
 					sw.WriteLine ();

tools/generator/InterfaceGen.cs

@@ -0,0 +1,50 @@
+using Java.Interop.Tools.TypeNameMappings;
+using Mono.Cecil;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace MonoDroid.Generation
+{
+#if HAVE_CECIL
+	internal static class ManagedExtensions
+	{
+		public static string FullNameCorrected (this TypeReference t) => t.FullName.Replace ('/', '.');
+
+		public static GenericParameterDefinitionList GenericArguments (this MethodDefinition m) => 
+			m.HasGenericParameters ? GenericParameterDefinitionList.FromMetadata (m.GenericParameters) : null;
+
+		public static string Deprecated (this MethodDefinition m)
+		{
+			var v = m.CustomAttributes.FirstOrDefault (a => a.AttributeType.FullName == "System.ObsoleteAttribute");
+			return v != null ? (string)v.ConstructorArguments [0].Value ?? "deprecated" : null;
+		}
+
+		public static string Visibility (this MethodDefinition m) =>
+			m.IsPublic ? "public" : m.IsFamilyOrAssembly ? "protected internal" : m.IsFamily ? "protected" : m.IsAssembly ? "internal" : "private";
+
+		public static IEnumerable<Parameter> GetParameters (this MethodDefinition m, CustomAttribute regatt)
+		{
+			var jnisig = (string)(regatt.ConstructorArguments.Count > 1 ? regatt.ConstructorArguments [1].Value : regatt.Properties.First (p => p.Name == "JniSignature").Argument.Value);
+			var types = jnisig == null ? null : JavaNativeTypeManager.FromSignature (jnisig);
+			var e = types?.GetEnumerator ();
+
+			foreach (var p in m.Parameters) {
+				if (e != null && !e.MoveNext ())
+					e = null;
+				// Here we do some tricky thing:
+				// Both java.io.InputStream and java.io.OutputStream could be mapped to
+				// System.IO.Stream. And when there is Stream in parameters, we have to
+				// determine which direction of the Stream it was - in or out.
+				// To do that, we inspect JNI Signature to handle that.
+				//
+				// We could *always* use this JNI information, *IF* there were no
+				// int->enum conversion. Sadly this is not true, we still have to expect
+				// custom enum types and cannot simply use JNI signature here.
+				var rawtype = e?.Current.Type;
+				var type = p.ParameterType.FullName == "System.IO.Stream" && e != null ? e.Current.Type : null;
+				yield return Parameter.FromManagedParameter (p, type, rawtype);
+			}
+		}
+	}
+#endif
+}