Reduce unnecessary heap allocations and improve efficiency

src/ComplexityRipper/Analysis/CSharpAnalyzer.cs

@@ -1,15 +1,17 @@
+using System.Text;
 using System.Text.RegularExpressions;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Microsoft.CodeAnalysis.Text;
 using ComplexityRipper.Models;
 
 namespace ComplexityRipper.Analysis;
 
 /// <summary>
 /// Analyzes C# source files using Roslyn to extract function-level metrics.
 /// </summary>
-public class CSharpAnalyzer
+public sealed class CSharpAnalyzer
 {
     /// <summary>
     /// Analyzes all .cs files under the given repo directories, running in parallel for performance.
@@ -45,10 +47,10 @@ public AnalysisResult AnalyzeRepos(string rootPath, Action<string>? onProgress =
                 ? Utilities.AdoUrlHelper.GetDefaultBranch(repoDir)
                 : "main";
 
+            var objSegment = $"{Path.DirectorySeparatorChar}obj{Path.DirectorySeparatorChar}";
+            var binSegment = $"{Path.DirectorySeparatorChar}bin{Path.DirectorySeparatorChar}";
             var csFiles = Directory.EnumerateFiles(repoDir, "*.cs", SearchOption.AllDirectories)
-                .Where(f => !f.Contains($"{Path.DirectorySeparatorChar}obj{Path.DirectorySeparatorChar}")
-                         && !f.Contains($"{Path.DirectorySeparatorChar}bin{Path.DirectorySeparatorChar}"))
-                .ToList();
+                .Where(f => !f.Contains(objSegment) && !f.Contains(binSegment));
 
             int functionCount = 0;
             int fileCount = 0;
@@ -187,8 +189,9 @@ public List<FunctionMetrics> AnalyzeFile(string filePath, string repoRoot, strin
 
         try
         {
-            var code = File.ReadAllText(filePath);
-            var tree = CSharpSyntaxTree.ParseText(code, path: filePath);
+            using var stream = File.OpenRead(filePath);
+            var sourceText = SourceText.From(stream, Encoding.UTF8);
+            var tree = CSharpSyntaxTree.ParseText(sourceText, path: filePath);
             var root = tree.GetRoot();
 
             var relativePath = Path.GetRelativePath(repoRoot, filePath);
@@ -270,16 +273,13 @@ private void AddFunction(SyntaxNode node, string functionName, int parameterCoun
             int endLine = lineSpan.EndLinePosition.Line + 1;
             int lineCount = endLine - startLine + 1;
 
-            // Find containing class/struct/record
             string? className = null;
-            var typeDecl = node.Ancestors().OfType<TypeDeclarationSyntax>().FirstOrDefault();
-            if (typeDecl != null)
+            // Materialize once to avoid re-enumerating the ancestor tree for Reverse/Select.
+            var typeAncestors = node.Ancestors().OfType<TypeDeclarationSyntax>().ToList();
+            if (typeAncestors.Count > 0)
             {
-                // Include nested type names
-                var typeNames = node.Ancestors().OfType<TypeDeclarationSyntax>()
-                    .Reverse()
-                    .Select(t => t.Identifier.Text);
-                className = string.Join(".", typeNames);
+                typeAncestors.Reverse();
+                className = string.Join(".", typeAncestors.Select(t => t.Identifier.Text));
             }
 
             // Find containing namespace
@@ -318,7 +318,7 @@ private void AddFunction(SyntaxNode node, string functionName, int parameterCoun
 /// </summary>
 internal class ProjectResolver
 {
-    private static readonly string[] ProjectExtensions = ["*.csproj", "*.fsproj", "*.vbproj"];
+    private static readonly string[] ProjectExtensions = [".csproj", ".fsproj", ".vbproj"];
     private readonly string _repoRoot;
     private readonly Dictionary<string, string?> _cache = new(StringComparer.OrdinalIgnoreCase);
 
@@ -344,10 +344,9 @@ public ProjectResolver(string repoRoot)
 
             foreach (var pattern in ProjectExtensions)
             {
-                var projFiles = Directory.GetFiles(dir, pattern);
-                if (projFiles.Length > 0)
+                foreach (var file in Directory.EnumerateFiles(dir, "*" + pattern))
                 {
-                    var name = Path.GetFileNameWithoutExtension(projFiles[0]);
+                    var name = Path.GetFileNameWithoutExtension(file);
                     CacheUpTo(Path.GetDirectoryName(Path.GetFullPath(sourceFilePath))!, dir, name);
                     return name;
                 }

src/ComplexityRipper/Models/AnalysisResult.cs

@@ -2,7 +2,7 @@
 
 namespace ComplexityRipper.Models;
 
-public class AnalysisResult
+public sealed class AnalysisResult
 {
     [JsonPropertyName("metadata")]
     public AnalysisMetadata Metadata { get; set; } = new();
@@ -17,7 +17,7 @@ public class AnalysisResult
     public List<FunctionMetrics> Functions { get; set; } = new();
 }
 
-public class AnalysisMetadata
+public sealed class AnalysisMetadata
 {
     [JsonPropertyName("generatedAt")]
     public DateTimeOffset GeneratedAt { get; set; } = DateTimeOffset.UtcNow;
@@ -29,7 +29,7 @@ public class AnalysisMetadata
     public Thresholds DefaultThresholds { get; set; } = new();
 }
 
-public class Thresholds
+public sealed class Thresholds
 {
     [JsonPropertyName("maxLines")]
     public int MaxLines { get; set; } = 200;
@@ -38,7 +38,7 @@ public class Thresholds
     public int MaxComplexity { get; set; } = 25;
 }
 
-public class RepoInfo
+public sealed class RepoInfo
 {
     [JsonPropertyName("name")]
     public string Name { get; set; } = string.Empty;
@@ -59,7 +59,7 @@ public class RepoInfo
     public int FunctionCount { get; set; }
 }
 
-public class AnalysisSummary
+public sealed class AnalysisSummary
 {
     [JsonPropertyName("totalRepos")]
     public int TotalRepos { get; set; }
@@ -74,7 +74,7 @@ public class AnalysisSummary
     public Dictionary<string, LanguageStats> LanguageBreakdown { get; set; } = new();
 }
 
-public class LanguageStats
+public sealed class LanguageStats
 {
     [JsonPropertyName("files")]
     public int Files { get; set; }

src/ComplexityRipper/Models/FunctionMetrics.cs

@@ -2,7 +2,7 @@
 
 namespace ComplexityRipper.Models;
 
-public class FunctionMetrics
+public sealed class FunctionMetrics
 {
     [JsonPropertyName("file")]
     public string File { get; set; } = string.Empty;

src/ComplexityRipper/Report/HtmlReportGenerator.cs

@@ -9,7 +9,7 @@ namespace ComplexityRipper.Report;
 /// Generates a self-contained HTML report from analysis results.
 /// Matches the dark GitHub-like theme of the existing build health report.
 /// </summary>
-public class HtmlReportGenerator
+public sealed class HtmlReportGenerator
 {
     public void Generate(AnalysisResult data, string outputPath, int thresholdLines = 200, int thresholdComplexity = 25, string theme = "light")
     {
@@ -19,7 +19,7 @@ public void Generate(AnalysisResult data, string outputPath, int thresholdLines
 
         var repoStats = data.Functions
             .GroupBy(f => f.Repo)
-            .Select(g => BuildRepoStats(g.Key, g.ToList(), repoLookup, thresholdLines, thresholdComplexity))
+            .Select(g => BuildRepoStats(g.Key, g, repoLookup, thresholdLines, thresholdComplexity))
             .OrderByDescending(r => r.ConcernScore)
             .ToList();
 
@@ -63,11 +63,12 @@ private record RepoStatsRow(
 
     private static RepoStatsRow BuildRepoStats(
         string repoName,
-        List<FunctionMetrics> functions,
+        IEnumerable<FunctionMetrics> functionsEnumerable,
         Dictionary<string, RepoInfo> repoLookup,
         int thresholdLines,
         int thresholdComplexity)
     {
+        var functions = functionsEnumerable.ToList();
         repoLookup.TryGetValue(repoName, out var info);
 
         var longFuncs = functions.Where(f => f.LineCount >= thresholdLines).OrderByDescending(f => f.LineCount).ToList();
@@ -524,14 +525,14 @@ private void AppendRepoFunctionTable(StringBuilder sb, string title, List<Functi
 
         sb.AppendLine($"<table id=\"{tableId}\">");
         sb.AppendLine("<thead><tr>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 0, 'string')\">Project <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 1, 'string')\">File <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 2, 'string')\">Class <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 3, 'string')\">Function <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 4, 'number')\" class=\"numeric\">Lines <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 5, 'number')\" class=\"numeric\">Complexity <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 6, 'number')\" class=\"numeric\">Params <span class=\"sort-arrow\">⇅</span></th>");
-        sb.AppendLine("<th onclick=\"sortTable('" + tableId + "', 7, 'number')\" class=\"numeric\">Nesting <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 0, 'string')\">Project <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 1, 'string')\">File <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 2, 'string')\">Class <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 3, 'string')\">Function <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 4, 'number')\" class=\"numeric\">Lines <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 5, 'number')\" class=\"numeric\">Complexity <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 6, 'number')\" class=\"numeric\">Params <span class=\"sort-arrow\">⇅</span></th>");
+        sb.AppendLine($"<th onclick=\"sortTable('{tableId}', 7, 'number')\" class=\"numeric\">Nesting <span class=\"sort-arrow\">⇅</span></th>");
         sb.AppendLine("</tr></thead>");
         sb.AppendLine("<tbody>");
 
@@ -685,13 +686,29 @@ private static string GetSeverityClass(int value, int criticalThreshold, int hig
 
     private static string GetShortFileName(string path)
     {
-        var parts = path.Replace('\\', '/').Split('/');
-        if (parts.Length <= 2)
+        var normalized = path.AsSpan();
+        int separatorCount = 0;
+        int secondLastSep = -1;
+
+        for (int i = normalized.Length - 1; i >= 0; i--)
+        {
+            if (normalized[i] == '/' || normalized[i] == '\\')
+            {
+                separatorCount++;
+                if (separatorCount == 2)
+                {
+                    secondLastSep = i;
+                    break;
+                }
+            }
+        }
+
+        if (secondLastSep < 0)
         {
             return path;
         }
 
-        return ".../" + string.Join("/", parts[^2..]);
+        return $".../{path[(secondLastSep + 1)..].Replace('\\', '/')}";
     }
 
     private static string Encode(string text) => HttpUtility.HtmlEncode(text);

src/ComplexityRipper/Utilities/AdoUrlHelper.cs

@@ -73,10 +73,10 @@ public static string GetDefaultBranch(string repoPath)
             string output = process.StandardOutput.ReadToEnd().Trim();
             process.WaitForExit(5000);
 
-            // Output: refs/remotes/origin/main
             if (!string.IsNullOrEmpty(output))
             {
-                return output.Split('/').Last();
+                var lastSlash = output.LastIndexOf('/');
+                return lastSlash >= 0 ? output[(lastSlash + 1)..] : output;
             }
         }
         catch
@@ -103,7 +103,7 @@ public static string GetDefaultBranch(string repoPath)
             }
 
             var urlAndSuffix = tabParts[1];
-            if (!urlAndSuffix.Contains("(fetch)"))
+            if (!urlAndSuffix.Contains("(fetch)", StringComparison.Ordinal))
             {
                 continue;
             }
@@ -114,7 +114,7 @@ public static string GetDefaultBranch(string repoPath)
 
             // ADO HTTPS: https://msdata@dev.azure.com/msdata/Sentinel%20Graph/_git/NEXT
             // Legacy:   https://msdata.visualstudio.com/DefaultCollection/Sentinel%20Graph/_git/PerfBenchInfra
-            if ((urlPart.Contains("dev.azure.com") || urlPart.Contains("visualstudio.com")) && urlPart.Contains("/_git/"))
+            if ((urlPart.Contains("dev.azure.com", StringComparison.Ordinal) || urlPart.Contains("visualstudio.com", StringComparison.Ordinal)) && urlPart.Contains("/_git/", StringComparison.Ordinal))
             {
                 var uri = new Uri(urlPart.Replace(" ", "%20"));
                 var segments = uri.AbsolutePath.Trim('/').Split('/');
@@ -131,30 +131,39 @@ public static string GetDefaultBranch(string repoPath)
                     string org;
                     string project;
 
-                    if (urlPart.Contains("dev.azure.com"))
+                    if (urlPart.Contains("dev.azure.com", StringComparison.Ordinal))
                     {
                         org = segments[0];
                         project = Uri.EscapeDataString(Uri.UnescapeDataString(
                             string.Join("/", segments[1..gitIdx])));
                     }
                     else
                     {
-                        // visualstudio.com: org is the subdomain (e.g., msdata.visualstudio.com -> msdata)
                         org = uri.Host.Split('.')[0];
-                        // Project is everything between DefaultCollection (or first segment) and _git
-                        var projectSegments = segments.TakeWhile(s => s != "_git")
-                            .Where(s => !s.Equals("DefaultCollection", StringComparison.OrdinalIgnoreCase))
-                            .ToArray();
+                        var projectParts = new List<string>();
+                        foreach (var s in segments)
+                        {
+                            if (s == "_git")
+                            {
+                                break;
+                            }
+
+                            if (!s.Equals("DefaultCollection", StringComparison.OrdinalIgnoreCase))
+                            {
+                                projectParts.Add(s);
+                            }
+                        }
+
                         project = Uri.EscapeDataString(Uri.UnescapeDataString(
-                            string.Join("/", projectSegments)));
+                            string.Join("/", projectParts)));
                     }
 
                     return $"https://dev.azure.com/{org}/{project}/_git/{repo}";
                 }
             }
 
             // ADO SSH: git@ssh.dev.azure.com:v3/{org}/{project}/{repo}
-            if (urlPart.Contains("ssh.dev.azure.com"))
+            if (urlPart.Contains("ssh.dev.azure.com", StringComparison.Ordinal))
             {
                 var parts = urlPart.Split(':');
                 if (parts.Length >= 2)
@@ -165,7 +174,7 @@ public static string GetDefaultBranch(string repoPath)
                         var org = pathParts[1];
                         var project = Uri.EscapeDataString(pathParts[2]);
                         var repo = pathParts[3].Split([' ', '\t'])[0];
-                        if (repo.EndsWith(".git"))
+                        if (repo.EndsWith(".git", StringComparison.Ordinal))
                         {
                             repo = repo[..^4];
                         }
@@ -176,10 +185,10 @@ public static string GetDefaultBranch(string repoPath)
             }
 
             // GitHub HTTPS: https://github.com/{owner}/{repo}.git
-            if (urlPart.Contains("github.com"))
+            if (urlPart.Contains("github.com", StringComparison.Ordinal))
             {
                 var cleaned = urlPart.TrimEnd('/');
-                if (cleaned.EndsWith(".git"))
+                if (cleaned.EndsWith(".git", StringComparison.Ordinal))
                 {
                     cleaned = cleaned[..^4];
                 }
@@ -200,10 +209,10 @@ public static string GetDefaultBranch(string repoPath)
             }
 
             // GitHub SSH: git@github.com:{owner}/{repo}.git
-            if (urlPart.StartsWith("git@github.com:"))
+            if (urlPart.StartsWith("git@github.com:", StringComparison.Ordinal))
             {
                 var path = urlPart["git@github.com:".Length..];
-                if (path.EndsWith(".git"))
+                if (path.EndsWith(".git", StringComparison.Ordinal))
                 {
                     path = path[..^4];
                 }
@@ -229,7 +238,7 @@ public static string GetDefaultBranch(string repoPath)
     /// <summary>
     /// Returns true if the base URL is a GitHub URL.
     /// </summary>
-    public static bool IsGitHub(string baseUrl) => baseUrl.Contains("github.com");
+    public static bool IsGitHub(string baseUrl) => baseUrl.Contains("github.com", StringComparison.Ordinal);
 
     /// <summary>
     /// Builds a URL to a specific file and line range, supporting both ADO and GitHub.