Feature: Add CanExecute to ReactiveCommand (#8)

* Feature Add CanExecute to ReactiveCommand

* Update to correct generator

Author: ChrisPulman

src/ReactiveUI.SourceGenerators.Execute/Program.cs

@@ -85,10 +85,18 @@ public TestClass()
         Console.ReadLine();
     }
 
+    /// <summary>
+    /// Gets the can execute test1.
+    /// </summary>
+    /// <value>
+    /// The can execute test1.
+    /// </value>
+    public IObservable<bool> CanExecuteTest1 => Observable.Return(true);
+
     /// <summary>
     /// Test1s this instance.
     /// </summary>
-    [ReactiveCommand]
+    [ReactiveCommand(CanExecute = nameof(CanExecuteTest1))]
     private void Test1() => Console.Out.WriteLine("Test1");
 
     /// <summary>

src/ReactiveUI.SourceGenerators/Attributes/ReactiveCommandAttribute.cs

@@ -12,4 +12,13 @@ namespace ReactiveUI.SourceGenerators;
 /// </summary>
 /// <seealso cref="Attribute" />
 [AttributeUsage(AttributeTargets.Method, AllowMultiple = false, Inherited = false)]
-public sealed class ReactiveCommandAttribute : Attribute;
+public sealed class ReactiveCommandAttribute : Attribute
+{
+    /// <summary>
+    /// Gets the can execute method or property.
+    /// </summary>
+    /// <value>
+    /// The name of the CanExecute Observable of bool.
+    /// </value>
+    public string? CanExecute { get; init; }
+}

src/ReactiveUI.SourceGenerators/Diagnostics/Analyzers/AsyncVoidReturningReactiveCommandMethodAnalyzer.cs

@@ -14,7 +14,7 @@
 namespace ReactiveUI.SourceGenerators;
 
 /// <summary>
-/// A diagnostic analyzer that generates a warning when using <c>[RelayCommand]</c> over an <see langword="async"/> <see cref="void"/> method.
+/// A diagnostic analyzer that generates a warning when using <c>[ReactiveCommand]</c> over an <see langword="async"/> <see cref="void"/> method.
 /// </summary>
 [DiagnosticAnalyzer(LanguageNames.CSharp)]
 public sealed class AsyncVoidReturningReactiveCommandMethodAnalyzer : DiagnosticAnalyzer

src/ReactiveUI.SourceGenerators/Reactive/ReactiveGenerator.Execute.cs

@@ -303,6 +303,27 @@ internal static bool GetFieldInfoFromClass(
             return true;
         }
 
+        /// <summary>
+        /// Get the generated property name for an input field.
+        /// </summary>
+        /// <param name="fieldSymbol">The input <see cref="IFieldSymbol"/> instance to process.</param>
+        /// <returns>The generated property name for <paramref name="fieldSymbol"/>.</returns>
+        internal static string GetGeneratedPropertyName(IFieldSymbol fieldSymbol)
+        {
+            var propertyName = fieldSymbol.Name;
+
+            if (propertyName.StartsWith("m_"))
+            {
+                propertyName = propertyName.Substring(2);
+            }
+            else if (propertyName.StartsWith("_"))
+            {
+                propertyName = propertyName.TrimStart('_');
+            }
+
+            return $"{char.ToUpper(propertyName[0], CultureInfo.InvariantCulture)}{propertyName.Substring(1)}";
+        }
+
         /// <summary>
         /// Validates the containing type for a given field being annotated.
         /// </summary>
@@ -357,26 +378,5 @@ private static void GetNullabilityInfo(
                 fieldSymbol.Type.NullableAnnotation != NullableAnnotation.Annotated &&
                 semanticModel.Compilation.HasAccessibleTypeWithMetadataName("System.Diagnostics.CodeAnalysis.MemberNotNullAttribute");
         }
-
-        /// <summary>
-        /// Get the generated property name for an input field.
-        /// </summary>
-        /// <param name="fieldSymbol">The input <see cref="IFieldSymbol"/> instance to process.</param>
-        /// <returns>The generated property name for <paramref name="fieldSymbol"/>.</returns>
-        private static string GetGeneratedPropertyName(IFieldSymbol fieldSymbol)
-        {
-            var propertyName = fieldSymbol.Name;
-
-            if (propertyName.StartsWith("m_"))
-            {
-                propertyName = propertyName.Substring(2);
-            }
-            else if (propertyName.StartsWith("_"))
-            {
-                propertyName = propertyName.TrimStart('_');
-            }
-
-            return $"{char.ToUpper(propertyName[0], CultureInfo.InvariantCulture)}{propertyName.Substring(1)}";
-        }
     }
 }

src/ReactiveUI.SourceGenerators/ReactiveCommand/Models/CanExecuteTypeInfo.cs

@@ -0,0 +1,12 @@
+// Copyright (c) 2024 .NET Foundation and Contributors. All rights reserved.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+namespace ReactiveUI.SourceGenerators.Input.Models;
+
+internal enum CanExecuteTypeInfo
+{
+    PropertyObservable,
+    MethodObservable
+}

src/ReactiveUI.SourceGenerators/ReactiveCommand/Models/CommandExtensionInfo.cs

@@ -4,6 +4,8 @@
 // See the LICENSE file in the project root for full license information.
 
 using Microsoft.CodeAnalysis;
+using ReactiveUI.SourceGenerators.Helpers;
+using ReactiveUI.SourceGenerators.Models;
 
 namespace ReactiveUI.SourceGenerators.Input.Models;
 
@@ -13,7 +15,11 @@ internal record CommandExtensionInfo(
     ITypeSymbol? ArgumentType,
     bool IsTask,
     bool IsReturnTypeVoid,
-    bool IsObservable)
+    bool IsObservable,
+    string? CanExecuteObservableName,
+    CanExecuteTypeInfo? CanExecuteTypeInfo,
+    EquatableArray<AttributeInfo> ForwardedFieldAttributes,
+    EquatableArray<AttributeInfo> ForwardedPropertyAttributes)
 {
     private const string UnitTypeName = "global::System.Reactive.Unit";