Update SnippetGenerator to be async

eng/SnippetGenerator/CSharpProcessor.cs

@@ -5,6 +5,7 @@
 using System.Security;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading.Tasks;
 
 namespace SnippetGenerator
 {
@@ -19,34 +20,30 @@ public class CSharpProcessor
         private static readonly Regex _snippetExampleRegex = new Regex("^(?<indent>\\s*)\\/{3}\\s*<example snippet=\"(?<name>[\\w:]+)\">.*?\\s*<\\/example>",
             RegexOptions.Compiled | RegexOptions.Multiline | RegexOptions.Singleline | RegexOptions.IgnoreCase);
 
-        public static string Process(string markdown, Func<string, string> snippetProvider)
+        public static async ValueTask<string> ProcessAsync(string markdown, Func<string, ValueTask<string>> snippetProvider)
         {
-            string CodeTagFormatter(Match match)
+            async ValueTask<string> CodeTagFormatter(Match match)
             {
-                var name = BuildResult(snippetProvider, match, out var prefix, out var builder);
-
-                return string.Format(_snippetFormat, name, Environment.NewLine, builder, prefix);
+                return await BuildResult(snippetProvider, match, _snippetFormat);
             }
 
-            string ExampleTagFormatter(Match match)
+            async ValueTask<string> ExampleTagFormatter(Match match)
             {
-                var name = BuildResult(snippetProvider, match, out var prefix, out var builder);
-
-                return string.Format(_snippetExampleFormat, name, Environment.NewLine, builder, prefix);
+                return await BuildResult(snippetProvider, match, _snippetExampleFormat);
             }
 
-            string result = _snippetRegex.Replace(markdown, CodeTagFormatter);
-            return result != markdown ? result : _snippetExampleRegex.Replace(markdown, ExampleTagFormatter);
+            string result = await _snippetRegex.ReplaceAsync(markdown, CodeTagFormatter);
+            return result != markdown ? result : await _snippetExampleRegex.ReplaceAsync(markdown, ExampleTagFormatter);
         }
 
-        private static string BuildResult(Func<string, string> snippetProvider, Match match, out string prefix, out StringBuilder builder)
+        private static async ValueTask<string> BuildResult(Func<string, ValueTask<string>> snippetProvider, Match match, string format)
         {
             var name = match.Groups["name"].Value;
-            prefix = match.Groups["indent"].Value + "///";
+            var prefix = match.Groups["indent"].Value + "///";
 
-            var snippetText = snippetProvider(name);
+            var snippetText = await snippetProvider(name);
 
-            builder = new StringBuilder();
+            var builder = new StringBuilder();
             foreach (var line in snippetText.Split(Environment.NewLine))
             {
                 builder.Append(prefix);
@@ -63,7 +60,7 @@ private static string BuildResult(Func<string, string> snippetProvider, Match ma
                 builder.Length -= Environment.NewLine.Length;
             }
 
-            return name;
+            return string.Format(format, name, Environment.NewLine, builder, prefix);
         }
     }
 }

eng/SnippetGenerator/DirectoryProcessor.cs

@@ -7,6 +7,7 @@
 using System.Linq;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
@@ -18,7 +19,7 @@ public class DirectoryProcessor
     {
         private const string _snippetPrefix = "Snippet:";
         private readonly string _directory;
-        private readonly Lazy<List<Snippet>> _snippets;
+        private readonly Lazy<Task<List<Snippet>>> _snippets;
         private static readonly Regex _markdownOnlyRegex = new Regex(
             @"(?<indent>\s*)//@@\s*(?<line>.*)",
             RegexOptions.Compiled | RegexOptions.Singleline | RegexOptions.CultureInvariant);
@@ -33,10 +34,10 @@ public class DirectoryProcessor
         public DirectoryProcessor(string directory)
         {
             _directory = directory;
-            _snippets = new Lazy<List<Snippet>>(DiscoverSnippets);
+            _snippets = new Lazy<Task<List<Snippet>>>(DiscoverSnippetsAsync);
         }
 
-        public void Process()
+        public async Task ProcessAsync()
         {
 
             List<string> files = new List<string>();
@@ -45,9 +46,10 @@ public void Process()
 
             foreach (var file in files)
             {
-                string SnippetProvider(string s)
+                async ValueTask<string> SnippetProvider(string s)
                 {
-                    var selectedSnippets = _snippets.Value.Where(snip => snip.Name == s).ToArray();
+                    var snippets = await _snippets.Value;
+                    var selectedSnippets = snippets.Where(snip => snip.Name == s).ToArray();
                     if (selectedSnippets.Length > 1)
                     {
                         throw new InvalidOperationException($"Multiple snippets with the name '{s}' defined '{_directory}'");
@@ -63,16 +65,16 @@ string SnippetProvider(string s)
                     return FormatSnippet(selectedSnippet.Text);
                 }
 
-                var originalText = File.ReadAllText(file);
+                var originalText = await File.ReadAllTextAsync(file);
 
                 string text;
                 switch (Path.GetExtension(file))
                 {
                     case ".md":
-                        text = MarkdownProcessor.Process(originalText, SnippetProvider);
+                        text = await MarkdownProcessor.ProcessAsync(originalText, SnippetProvider);
                         break;
                     case ".cs":
-                        text = CSharpProcessor.Process(originalText, SnippetProvider);
+                        text = await CSharpProcessor.ProcessAsync(originalText, SnippetProvider);
                         break;
                     default:
                         throw new NotSupportedException(file);
@@ -81,14 +83,14 @@ string SnippetProvider(string s)
                 if (text != originalText)
                 {
                     _utf8EncodingWithoutBOM = new UTF8Encoding(false);
-                    File.WriteAllText(file, text, _utf8EncodingWithoutBOM);
+                    await File.WriteAllTextAsync(file, text, _utf8EncodingWithoutBOM);
                 }
             }
         }
 
-        private List<Snippet> DiscoverSnippets()
+        private async Task<List<Snippet>> DiscoverSnippetsAsync()
         {
-            var snippets = GetSnippetsInDirectory(_directory);
+            var snippets = await GetSnippetsInDirectoryAsync(_directory);
             Console.WriteLine($"Discovered snippets:");
 
             foreach (var snippet in snippets)
@@ -200,15 +202,21 @@ private static bool IsCodeOnlyLine(string line) =>
         private static bool IsRegionLine(string line) =>
             _regionRegex.IsMatch(line);
 
-        private List<Snippet> GetSnippetsInDirectory(string baseDirectory)
+        private async Task<List<Snippet>> GetSnippetsInDirectoryAsync(string baseDirectory)
         {
             var list = new List<Snippet>();
             foreach (var file in Directory.GetFiles(baseDirectory, "*.cs", SearchOption.AllDirectories))
             {
                 try
                 {
+                    var text = await File.ReadAllTextAsync(file);
+                    if (!text.Contains($"#region {_snippetPrefix}"))
+                    {
+                        continue;
+                    }
+
                     var syntaxTree = CSharpSyntaxTree.ParseText(
-                        File.ReadAllText(file),
+                        text,
                         new CSharpParseOptions(LanguageVersion.Preview, preprocessorSymbols: _snippetPreprocessorSymbols),
                         path: file);
 

eng/SnippetGenerator/MarkdownProcessor.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Text.RegularExpressions;
+using System.Threading.Tasks;
 
 namespace SnippetGenerator
 {
@@ -12,14 +13,14 @@ public class MarkdownProcessor
         private static readonly Regex _snippetRegex = new Regex("```\\s*?C#[ ]*?(?<name>[\\w:]+).*?```",
             RegexOptions.Compiled | RegexOptions.Multiline | RegexOptions.Singleline | RegexOptions.IgnoreCase);
 
-        public static string Process(string markdown, Func<string, string> snippetProvider)
+        public static async Task<string> ProcessAsync(string markdown, Func<string, ValueTask<string>> snippetProvider)
         {
-            return _snippetRegex.Replace(markdown, match =>
+            return await _snippetRegex.ReplaceAsync(markdown, async match =>
             {
                 var matchGroup = match.Groups["name"];
                 if (matchGroup.Success)
                 {
-                    return string.Format(_snippetFormat, matchGroup.Value, Environment.NewLine, snippetProvider(matchGroup.Value));
+                    return string.Format(_snippetFormat, matchGroup.Value, Environment.NewLine, await snippetProvider(matchGroup.Value));
                 }
 
                 return match.Value;

eng/SnippetGenerator/Program.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT License.
 
 using System;
+using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Threading.Tasks;
@@ -16,16 +17,22 @@ public class Program
         [Option(ShortName = "b")]
         public string BasePath { get; set; }
 
-        public void OnExecuteAsync()
+        public async Task OnExecuteAsync()
         {
             var baseDirectory = new DirectoryInfo(BasePath).Name;
             if (baseDirectory.Equals("sdk"))
             {
-                Parallel.ForEach(Directory.GetDirectories(BasePath), sdkDir => new DirectoryProcessor(sdkDir).Process());
+                var tasks = new List<Task>();
+                foreach (var sdkDir in Directory.GetDirectories(BasePath))
+                {
+                    tasks.Add(new DirectoryProcessor(sdkDir).ProcessAsync());
+                }
+
+                await Task.WhenAll(tasks);
             }
             else
             {
-                new DirectoryProcessor(BasePath).Process();
+                await new DirectoryProcessor(BasePath).ProcessAsync();
             }
         }
 

eng/SnippetGenerator/RegexAsyncExtensions.cs

@@ -0,0 +1,30 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System;
+using System.Text;
+using System.Text.RegularExpressions;
+using System.Threading.Tasks;
+
+namespace SnippetGenerator
+{
+    internal static class RegexAsyncExtensions
+    {
+        public static async ValueTask<string> ReplaceAsync(this Regex regex, string input, Func<Match, ValueTask<string>> replacementFn)
+        {
+            var sb = new StringBuilder();
+            var lastIndex = 0;
+
+            foreach (Match match in regex.Matches(input))
+            {
+                sb.Append(input, lastIndex, match.Index - lastIndex)
+                    .Append(await replacementFn(match).ConfigureAwait(false));
+
+                lastIndex = match.Index + match.Length;
+            }
+
+            sb.Append(input, lastIndex, input.Length - lastIndex);
+            return sb.ToString();
+        }
+    }
+}

eng/SnippetGenerator/SnippetGenerator.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <OutputType>Exe</OutputType>
-    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <TargetFramework>net5.0</TargetFramework>
   </PropertyGroup>
 
   <ItemGroup>

eng/scripts/Update-Snippets.ps1

@@ -14,4 +14,4 @@ if ($ServiceDirectory -and ($ServiceDirectory -ne "*")) {
     $root += '/' + $ServiceDirectory
 }
 
-Resolve-Path "$root" | %{ dotnet run -p $generatorProject -b "$_" }
+Resolve-Path "$root" | %{ dotnet run -p $generatorProject -b "$_" -c Release }