From ad2dce3ae9547448f08a392e3b2cfbb245fa04df Mon Sep 17 00:00:00 2001
From: Konstantin Diachenko <drakonard@gmail.com>
Date: Fri, 28 Feb 2020 18:18:26 +0300
Subject: [PATCH] Create only those folder that contain files while tranlating
 in folder to folder mode.

---
 .../FileTransformerTests.cs                   |  2 ++
 .../FileTransformer.cs                        | 31 ++++++++++++++++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/csharp/Platform.RegularExpressions.Transformer.Tests/FileTransformerTests.cs b/csharp/Platform.RegularExpressions.Transformer.Tests/FileTransformerTests.cs
index ba83d34..034a430 100644
--- a/csharp/Platform.RegularExpressions.Transformer.Tests/FileTransformerTests.cs
+++ b/csharp/Platform.RegularExpressions.Transformer.Tests/FileTransformerTests.cs
@@ -35,6 +35,7 @@ public void FolderToFolderTransfomationTest()
             File.WriteAllText(Path.Combine(sourceFolderPath, "a.cs"), "a a a");
             var aFolderPath = Path.Combine(sourceFolderPath, "A");
             Directory.CreateDirectory(aFolderPath);
+            Directory.CreateDirectory(Path.Combine(sourceFolderPath, "B"));
             File.WriteAllText(Path.Combine(aFolderPath, "b.cs"), "b b b");
             File.WriteAllText(Path.Combine(sourceFolderPath, "x.txt"), "should not be translated");
 
@@ -44,6 +45,7 @@ public void FolderToFolderTransfomationTest()
             Assert.True(File.Exists(aCppFile));
             Assert.Equal("c c c", File.ReadAllText(aCppFile));
             Assert.True(Directory.Exists(Path.Combine(targetFolderPath, "A")));
+            Assert.False(Directory.Exists(Path.Combine(targetFolderPath, "B")));
             var bCppFile = Path.Combine(targetFolderPath, "A", "b.cpp");
             Assert.True(File.Exists(bCppFile));
             Assert.Equal("c c c", File.ReadAllText(bCppFile));
diff --git a/csharp/Platform.RegularExpressions.Transformer/FileTransformer.cs b/csharp/Platform.RegularExpressions.Transformer/FileTransformer.cs
index 77e6959..b69b1f4 100644
--- a/csharp/Platform.RegularExpressions.Transformer/FileTransformer.cs
+++ b/csharp/Platform.RegularExpressions.Transformer/FileTransformer.cs
@@ -86,23 +86,23 @@ public void Transform(string sourcePath, string targetPath)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         protected virtual void TransformFolder(string sourcePath, string targetPath)
         {
-            var files = Directory.GetFiles(sourcePath);
-            var directories = Directory.GetDirectories(sourcePath);
-            if (files.Length == 0 && directories.Length == 0)
+            if (CountFilesRecursively(sourcePath, SourceFileExtension) == 0)
             {
                 return;
             }
             EnsureTargetDirectoryExists(targetPath);
+            var directories = Directory.GetDirectories(sourcePath);
             for (var i = 0; i < directories.Length; i++)
             {
                 var relativePath = GetRelativePath(sourcePath, directories[i]);
                 var newTargetPath = Path.Combine(targetPath, relativePath);
                 TransformFolder(directories[i], newTargetPath);
             }
+            var files = Directory.GetFiles(sourcePath);
             Parallel.For(0, files.Length, i =>
             {
                 var file = files[i];
-                if (file.EndsWith(SourceFileExtension, StringComparison.OrdinalIgnoreCase))
+                if (FileExtensionMatches(file, SourceFileExtension))
                 {
                     TransformFile(file, GetTargetFileName(file, targetPath));
                 }
@@ -129,6 +129,29 @@ protected virtual void TransformFile(string sourcePath, string targetPath)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         protected string GetTargetFileName(string sourcePath, string targetDirectory) => Path.ChangeExtension(Path.Combine(targetDirectory, Path.GetFileName(sourcePath)), TargetFileExtension);
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static long CountFilesRecursively(string path, string extension)
+        {
+            var files = Directory.GetFiles(path);
+            var directories = Directory.GetDirectories(path);
+            var result = 0L;
+            for (var i = 0; i < directories.Length; i++)
+            {
+                result += CountFilesRecursively(directories[i], extension);
+            }
+            for (var i = 0; i < files.Length; i++)
+            {
+                if (FileExtensionMatches(files[i], extension))
+                {
+                    result++;
+                }
+            }
+            return result;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        private static bool FileExtensionMatches(string file, string extension) => file.EndsWith(extension, StringComparison.OrdinalIgnoreCase);
+
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private static void EnsureTargetFileDirectoryExists(string targetPath)
         {