Refactor (#94)

CliFx.Analyzers/ParameterMustHaveUniqueOrderAnalyzer.cs

@@ -0,0 +1,59 @@
+using System.Linq;
+using CliFx.Analyzers.ObjectModel;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Diagnostics;
+
+namespace CliFx.Analyzers
+{
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public class ParameterMustHaveUniqueOrderAnalyzer : AnalyzerBase
+    {
+        public ParameterMustHaveUniqueOrderAnalyzer()
+            : base(
+                "Parameters must have unique order",
+                "This parameter's order must be unique within the command.")
+        {
+        }
+
+        private void Analyze(SyntaxNodeAnalysisContext context)
+        {
+            if (context.Node is not PropertyDeclarationSyntax propertyDeclaration)
+                return;
+
+            var property = context.SemanticModel.GetDeclaredSymbol(propertyDeclaration);
+            if (property is null)
+                return;
+
+            var parameter = CommandParameterSymbol.TryResolve(property);
+            if (parameter is null)
+                return;
+
+            var otherProperties = property
+                .ContainingType
+                .GetMembers()
+                .OfType<IPropertySymbol>()
+                .Where(m => !m.Equals(property, SymbolEqualityComparer.Default))
+                .ToArray();
+
+            foreach (var otherProperty in otherProperties)
+            {
+                var otherParameter = CommandParameterSymbol.TryResolve(otherProperty);
+                if (otherParameter is null)
+                    continue;
+
+                if (parameter.Order == otherParameter.Order)
+                {
+                    context.ReportDiagnostic(CreateDiagnostic(propertyDeclaration.GetLocation()));
+                }
+            }
+        }
+
+        public override void Initialize(AnalysisContext context)
+        {
+            base.Initialize(context);
+            context.RegisterSyntaxNodeAction(Analyze, SyntaxKind.PropertyDeclaration);
+        }
+    }
+}