Improve ImplementMethod, remove invalidation, and cache freezing (#373)

- ImplementMethod now only takes one argument
- Remove Invalidation hack - https://github.com/mono/Embeddinator-4000/issues/370
- Semi implement freezing. We now only cache after freezing. Later we can look at improved permissions or exceptions - https://github.com/mono/Embeddinator-4000/issues/371

objcgen/CachedValue.cs

@@ -0,0 +1,30 @@
+using System;
+
+namespace Embeddinator
+{
+	class CachedValue<T> where T : class
+	{
+		Func<T> CalculateProc;
+		T LastCalculatedValue;
+
+		public bool IsFrozen { get; private set; }
+		public void Freeze () => IsFrozen = true;
+
+		public CachedValue (Func<T> calculateProc)
+		{
+			CalculateProc = calculateProc;
+		}
+
+		public T Value {
+			get {
+				if (IsFrozen) {
+					if (LastCalculatedValue == null)
+						LastCalculatedValue = CalculateProc ();
+					return LastCalculatedValue;
+				} else {
+					return CalculateProc ();
+				}
+			}
+		}
+	}
+}

objcgen/objcgen.csproj

@@ -326,6 +326,7 @@
     <Compile Include="system-check.cs" />
     <Compile Include="embedder.cs" />
     <Compile Include="utils.cs" />
+    <Compile Include="CachedValue.cs" />
   </ItemGroup>
   <ItemGroup>
     <Folder Include="support\" />

objcgen/objcgenerator-postprocessor.cs

@@ -39,6 +39,7 @@ namespace ObjC {
 
 				ProcessPotentialName (processedMethod);
 
+				processedMethod.Freeze ();
 				yield return processedMethod;
 			}
 		}
@@ -72,6 +73,7 @@ namespace ObjC {
 
 				ProcessPotentialName (processedProperty);
 
+				processedProperty.Freeze ();
 				yield return processedProperty;
 			}
 		}
@@ -126,6 +128,7 @@ namespace ObjC {
 				if (duplicateNames.Contains (CreateStringRep(constructor)))
 					processedConstructor.FallBackToTypeName = true;
 
+				processedConstructor.Freeze ();
 				yield return processedConstructor;
 			}
 		}

objcgen/objcgenerator.cs

@@ -166,7 +166,7 @@ namespace ObjC {
 			implementation.WriteLine ();
 
 			foreach (var mi in methods) {
-				ImplementMethod (mi.Method, mi.Method.Name.CamelCase (), mi, isExtension: true);
+				ImplementMethod (mi);
 			}
 
 			headers.WriteLine ("@end");
@@ -791,11 +791,11 @@ namespace ObjC {
 			var spacing = property_type [property_type.Length - 1] == '*' ? string.Empty : " ";
 			headers.WriteLine ($") {property_type}{spacing}{property.Name};");
 
-			ImplementMethod (getter.Method, property.GetterName, property.GetMethod, pi: property.Property);
+			ImplementMethod (property.GetMethod);
 			if (setter == null)
 				return;
 
-			ImplementMethod (setter.Method, property.SetterName, property.SetMethod, pi: property.Property);
+			ImplementMethod (property.SetMethod);
 		}
 
 		protected void Generate (ProcessedFieldInfo field)
@@ -905,24 +905,19 @@ namespace ObjC {
 		}
 
 		// TODO override with attribute ? e.g. [ObjC.Selector ("foo")]
-		// HACK - This should take a ProcessedMethod and not much of this stuff - https://github.com/mono/Embeddinator-4000/issues/276
-		string ImplementMethod (MethodInfo info, string name, ProcessedMethod method, bool isExtension = false, PropertyInfo pi = null)
+		string ImplementMethod (ProcessedMethod method)
 		{
+			MethodInfo info = method.Method;
+
 			var type = info.DeclaringType;
 			var managed_type_name = NameGenerator.GetObjCName (type);
 
-			if (method.NameOverride == null)
-				method.NameOverride = name;
-			
-			method.IsExtension = isExtension;
-
-			method.Invalidate ();
 			string objcsig = method.ObjCSignature;
 
 			var builder = new MethodHelper (headers, implementation) {
 				AssemblySafeName = type.Assembly.GetName ().Name.Sanitize (),
 				IsStatic = info.IsStatic,
-				IsExtension = isExtension,
+				IsExtension = method.IsExtension,
 				ReturnType = GetReturnType (type, info.ReturnType),
 				ManagedTypeName = type.FullName,
 				MetadataToken = info.MetadataToken,
@@ -933,7 +928,7 @@ namespace ObjC {
 				IsVirtual = info.IsVirtual && !info.IsFinal,
 			};
 
-			if (pi == null)
+			if (!method.IsPropertyImplementation)
 				builder.WriteHeaders ();
 			
 			builder.BeginImplementation ();
@@ -943,7 +938,7 @@ namespace ObjC {
 			string postInvoke = String.Empty;
 			var args = "nil";
 			if (parametersInfo.Length > 0) {
-				Generate (parametersInfo, isExtension, out postInvoke);
+				Generate (parametersInfo, method.IsExtension, out postInvoke);
 				args = "__args";
 			}
 
@@ -1034,7 +1029,7 @@ namespace ObjC {
 				builder = new EquatableHelper (method, headers, implementation);
 				break;
 			default:
-				ImplementMethod (method.Method, method.BaseName, method);
+				ImplementMethod (method);
 				return;
 			}
 			builder.WriteHeaders ();

objcgen/objcprocessor.cs

@@ -307,7 +307,7 @@ namespace ObjC {
 							extmethods = new List<ProcessedMethod> ();
 							extensions.Add (extended_type, extmethods);
 						}
-						extmethods.Add (new ProcessedMethod  (mi, this));
+						extmethods.Add (new ProcessedMethod  (mi, this) { IsExtension = true } );
 						continue;
 					}
 				}

objcgen/processedtypes.cs

@@ -154,51 +154,34 @@ namespace Embeddinator {
 	public abstract class ProcessedMemberWithParameters : ProcessedMemberBase {
 		public ProcessedMemberWithParameters (Processor processor) : base (processor)
 		{
+			objCSignature = new CachedValue<string> (GetObjcSignature);
+			monoSignature = new CachedValue<string> (GetMonoSignature);
 		}
 
 		public abstract string BaseName { get; }
 
 		public ParameterInfo[] Parameters { get; protected set; }
-
-		[Obsolete] // https://github.com/mono/Embeddinator-4000/issues/370
-		public void Invalidate ()
-		{
-			objCSignature = null;
-			monoSignature = null;
-		}
-
-		string objCSignature;
-		public string ObjCSignature {
-			get {
-				if (objCSignature == null)
-					ComputeSignatures ();
-				return objCSignature;
-			}
-			protected set {
-				objCSignature = value;
-			}
-		}
-
-		string monoSignature;
-		public string MonoSignature {
-			get {
-				if (monoSignature == null)
-					ComputeSignatures ();
-				return monoSignature;
-			}
-			protected set {
-				monoSignature = value;
-			}
-		}
-
-		protected abstract void ComputeSignatures ();
-
 		public int FirstDefaultParameter { get; set; }
+
+		protected abstract string GetObjcSignature ();
+		CachedValue<string> objCSignature;
+		public string ObjCSignature => objCSignature.Value;
+
+		protected abstract string GetMonoSignature ();
+		CachedValue<string> monoSignature;
+		public string MonoSignature => monoSignature.Value;
+
+		public void Freeze ()
+		{
+			objCSignature.Freeze ();
+			monoSignature.Freeze ();
+		}
 	}
 
 	public class ProcessedMethod : ProcessedMemberWithParameters {
 		public MethodInfo Method { get; private set; }
 		public bool IsOperator { get; set; }
+		public bool IsPropertyImplementation { get; set; }
 
 		public string NameOverride { get; set; }
 		public string ManagedName { get; set; }
@@ -223,15 +206,9 @@ namespace Embeddinator {
 			FirstDefaultParameter = -1;
 		}
 
-		protected override void ComputeSignatures ()
-		{
-			ObjCSignature = GetObjcSignature ();
-			MonoSignature = GetMonoSignature ();
-		}
-
 		public override string ToString () => ToString (Method);
 
-		string GetMonoSignature ()
+		protected override string GetMonoSignature ()
 		{
 			var mono = new StringBuilder (Method.Name);
 
@@ -249,7 +226,7 @@ namespace Embeddinator {
 			return mono.ToString ();
 		}
 
-		string GetObjcSignature ()
+		protected override string GetObjcSignature ()
 		{
 			string objName = BaseName;
 
@@ -290,14 +267,20 @@ namespace Embeddinator {
 		public ProcessedProperty (PropertyInfo property, Processor processor) : base (processor)
 		{
 			Property = property;
-
-			var g = Property.GetGetMethod ();
-			if (g != null)
-				GetMethod = new ProcessedMethod (g, Processor);
-
-			var s = Property.GetSetMethod ();
-			if (s != null)
-				SetMethod = new ProcessedMethod (s, Processor);
+			getMethod = new CachedValue<ProcessedMethod> (() => {
+				var getter = Property.GetGetMethod ();
+				if (getter != null) {
+					return new ProcessedMethod (getter, Processor) { NameOverride = GetterName, IsPropertyImplementation = true };
+				}
+				return null;
+			});
+			setMethod = new CachedValue<ProcessedMethod> (() => {
+				var setter = Property.GetSetMethod ();
+				if (setter != null) {
+					return new ProcessedMethod (setter, Processor) { NameOverride = SetterName, IsPropertyImplementation = true };
+				}
+				return null;
+			});
 		}
 
 		public override string ToString () => Property.ToString ();
@@ -305,8 +288,8 @@ namespace Embeddinator {
 		public string Name => NameOverride != null ? NameOverride : Property.Name.CamelCase ();
 		public string NameOverride { get; set; }
 
-		public bool HasGetter => GetMethod != null;
-		public bool HasSetter => SetMethod != null;
+		public bool HasGetter => Property.GetGetMethod () != null;
+		public bool HasSetter => Property.GetSetMethod () != null;
 
 		public string GetterName {
 			get {
@@ -324,8 +307,17 @@ namespace Embeddinator {
 			}
 		}
 
-		public ProcessedMethod GetMethod { get; private set; }
-		public ProcessedMethod SetMethod { get; private set; }
+		CachedValue<ProcessedMethod> getMethod;
+		public ProcessedMethod GetMethod => getMethod.Value;
+
+		CachedValue<ProcessedMethod> setMethod;
+		public ProcessedMethod SetMethod => setMethod.Value;
+
+		public void Freeze ()
+		{
+			getMethod.Freeze ();
+			setMethod.Freeze ();
+		}
 	}
 
 	public enum ConstructorType {
@@ -354,15 +346,9 @@ namespace Embeddinator {
 			FirstDefaultParameter = -1;
 		}
 
-		protected override void ComputeSignatures ()
-		{
-			ObjCSignature = GetObjcSignature ();
-			MonoSignature = GetMonoSignature ();
-		}
-
 		public override string ToString () => ToString (Constructor);
 
-		string GetMonoSignature ()
+		protected override string GetMonoSignature ()
 		{
 			var mono = new StringBuilder (Constructor.Name);
 
@@ -380,7 +366,7 @@ namespace Embeddinator {
 			return mono.ToString ();
 		}
 
-		string GetObjcSignature ()
+		protected override string GetObjcSignature ()
 		{
 			var objc = new StringBuilder (BaseName);