GeneratedCodeAnalysisExtensions.cs

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using System.Linq;
using System.Text.RegularExpressions;

namespace CodeCracker
{
    public static class GeneratedCodeAnalysisExtensions
    {
        public static bool IsGenerated(this SyntaxNodeAnalysisContext context) => (context.SemanticModel?.SyntaxTree?.IsGenerated() ?? false) || (context.Node?.IsGenerated() ?? false);

        public static bool IsGenerated(this SyntaxTreeAnalysisContext context) => context.Tree?.IsGenerated() ?? false;

        public static bool IsGenerated(this SymbolAnalysisContext context)
        {
            if (context.Symbol == null) return false;
            foreach (var syntaxReference in context.Symbol.DeclaringSyntaxReferences)
            {
                if (syntaxReference.SyntaxTree.IsGenerated()) return true;
                var root = syntaxReference.SyntaxTree.GetRoot();
                var node = root?.FindNode(syntaxReference.Span);
                if (node.IsGenerated()) return true;
            }
            return false;
        }

        public static bool IsGenerated(this SyntaxNode node) => node.HasAttributeOnAncestorOrSelf("DebuggerNonUserCode", "GeneratedCode");

        public static bool IsGenerated(this SyntaxTree tree) => (tree.FilePath?.IsOnGeneratedFile() ?? false) || tree.HasAutoGeneratedComment();

        public static bool HasAutoGeneratedComment(this SyntaxTree tree)
        {
            var root = tree.GetRoot();
            if (root == null) return false;
            var isCSharp = root is CompilationUnitSyntax;
            var firstToken = root.GetFirstToken();
            SyntaxTriviaList trivia;
            if (firstToken == default(SyntaxToken))
            {
                var token = isCSharp
                    ? ((CompilationUnitSyntax)root).EndOfFileToken
                    : ((Microsoft.CodeAnalysis.VisualBasic.Syntax.CompilationUnitSyntax)root).EndOfFileToken;
                if (!token.HasLeadingTrivia) return false;
                trivia = token.LeadingTrivia;
            }
            else
            {
                if (!firstToken.HasLeadingTrivia) return false;
                trivia = firstToken.LeadingTrivia;
            }
            if (isCSharp)
            {
                var commentLines = trivia.Where(t => t.IsKind(SyntaxKind.SingleLineCommentTrivia)).Take(2).ToList();
                if (commentLines.Count != 2) return false;
                return commentLines[1].ToString() == "// <auto-generated>";
            }
            else
            {
                var commentLines = trivia.Where(t => t.IsKind(Microsoft.CodeAnalysis.VisualBasic.SyntaxKind.CommentTrivia)).Take(2).ToList();
                if (commentLines.Count != 2) return false;
                return commentLines[1].ToString() == "' <auto-generated>";
            }
        }

        public static bool IsOnGeneratedFile(this string filePath) =>
            Regex.IsMatch(filePath, @"(\\service|\\TemporaryGeneratedFile_.*|\\assemblyinfo|\\assemblyattributes|\.(g\.i|g|designer|generated|assemblyattributes))\.(cs|vb)$",
                RegexOptions.IgnoreCase);
    }
}