Add DocumentValueFromSummary analyzer and code fix

Fixes #6

Author: sharwell

OpenStackNetAnalyzers/OpenStackNetAnalyzers/DocumentValueFromSummaryAnalyzer.cs

@@ -0,0 +1,119 @@
+namespace OpenStackNetAnalyzers
+{
+    using System;
+    using System.Collections.Immutable;
+    using System.Linq;
+    using Microsoft.CodeAnalysis;
+    using Microsoft.CodeAnalysis.CSharp;
+    using Microsoft.CodeAnalysis.CSharp.Syntax;
+    using Microsoft.CodeAnalysis.Diagnostics;
+
+    [DiagnosticAnalyzer(LanguageNames.CSharp)]
+    public class DocumentValueFromSummaryAnalyzer : DiagnosticAnalyzer
+    {
+        public const string DiagnosticId = "DocumentValueFromSummary";
+        internal const string Title = "JSON property values should be documented";
+        internal const string MessageFormat = "JSON property values should be documented";
+        internal const string Category = "OpenStack.Documentation";
+        internal const string Description = "JSON property values should be documented";
+
+        private static DiagnosticDescriptor Descriptor =
+            new DiagnosticDescriptor(DiagnosticId, Title, MessageFormat, Category, DiagnosticSeverity.Warning, isEnabledByDefault: true, description: Description);
+
+        private static readonly ImmutableArray<DiagnosticDescriptor> _supportedDiagnostics =
+            ImmutableArray.Create(Descriptor);
+
+        public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
+        {
+            get
+            {
+                return _supportedDiagnostics;
+            }
+        }
+
+        public override void Initialize(AnalysisContext context)
+        {
+            context.RegisterSyntaxNodeAction(HandlePropertyDeclaration, SyntaxKind.PropertyDeclaration);
+        }
+
+        private void HandlePropertyDeclaration(SyntaxNodeAnalysisContext context)
+        {
+            PropertyDeclarationSyntax syntax = (PropertyDeclarationSyntax)context.Node;
+            if (syntax.Identifier.IsMissing)
+                return;
+
+            if (!syntax.Modifiers.Any(SyntaxKind.PublicKeyword) && !syntax.Modifiers.Any(SyntaxKind.ProtectedKeyword))
+                return;
+
+            SemanticModel semanticModel = context.SemanticModel;
+            IPropertySymbol propertySymbol = semanticModel.GetDeclaredSymbol(syntax, context.CancellationToken);
+            if (propertySymbol == null)
+                return;
+
+            INamedTypeSymbol declaringType = propertySymbol.ContainingType;
+            if (!IsExtensibleJsonObject(declaringType))
+                return;
+
+            DocumentationCommentTriviaSyntax documentationTriviaSyntax = GetDocumentationCommentTriviaSyntax(syntax);
+            if (documentationTriviaSyntax == null)
+                return;
+
+            XmlNodeSyntax valueNode = GetXmlElement(documentationTriviaSyntax.Content, "value");
+            if (valueNode != null)
+                return;
+
+            context.ReportDiagnostic(Diagnostic.Create(Descriptor, syntax.Identifier.GetLocation()));
+        }
+
+        private bool IsExtensibleJsonObject(INamedTypeSymbol symbol)
+        {
+            while (symbol != null && symbol.SpecialType != SpecialType.System_Object)
+            {
+                if (string.Equals("global::OpenStack.ObjectModel.ExtensibleJsonObject", symbol.ToDisplayString(SymbolDisplayFormat.FullyQualifiedFormat), StringComparison.Ordinal))
+                    return true;
+
+                symbol = symbol.BaseType;
+            }
+
+            return false;
+        }
+
+        internal static DocumentationCommentTriviaSyntax GetDocumentationCommentTriviaSyntax(SyntaxNode node)
+        {
+            if (node == null)
+                return null;
+
+            return node
+                .GetLeadingTrivia()
+                .Select(i => i.GetStructure())
+                .OfType<DocumentationCommentTriviaSyntax>()
+                .FirstOrDefault();
+        }
+
+        internal static XmlNodeSyntax GetXmlElement(SyntaxList<XmlNodeSyntax> content, string elementName)
+        {
+            foreach (XmlNodeSyntax syntax in content)
+            {
+                XmlEmptyElementSyntax emptyElement = syntax as XmlEmptyElementSyntax;
+                if (emptyElement != null)
+                {
+                    if (string.Equals(elementName, emptyElement.Name.ToString(), StringComparison.Ordinal))
+                        return emptyElement;
+
+                    continue;
+                }
+
+                XmlElementSyntax elementSyntax = syntax as XmlElementSyntax;
+                if (elementSyntax != null)
+                {
+                    if (string.Equals(elementName, elementSyntax.StartTag?.Name?.ToString(), StringComparison.Ordinal))
+                        return elementSyntax;
+
+                    continue;
+                }
+            }
+
+            return null;
+        }
+    }
+}