Update FilePath::getFilesInDirectory to allow getting all files (AcademySoftwareFoundation#2633)

While working on some other internal projects I found myself using the `FilePath` object, and bumped up against the fact that `getFilesInDirectory` is unable to query all the files in the provided directory.

This PR provides a simple extension to the existing code to allow accessing all the files in a directory if no extension is provided to match against.

Author: ld-kerley

source/MaterialXFormat/File.cpp

@@ -185,8 +185,8 @@ FilePathVec FilePath::getFilesInDirectory(const string& extension) const
 
 #if defined(_WIN32)
     WIN32_FIND_DATAA fd;
-    string wildcard = "*." + extension;
-    HANDLE hFind = FindFirstFileA((*this / wildcard).asString().c_str(), &fd);
+    FilePath query = extension.empty() ? *this : (*this / ("*." + extension));
+    HANDLE hFind = FindFirstFileA(query.asString().c_str(), &fd);
     if (hFind != INVALID_HANDLE_VALUE)
     {
         do
@@ -204,7 +204,7 @@ FilePathVec FilePath::getFilesInDirectory(const string& extension) const
     {
         while (struct dirent* entry = readdir(dir))
         {
-            if (entry->d_type != DT_DIR && FilePath(entry->d_name).getExtension() == extension)
+            if (entry->d_type != DT_DIR && (extension.empty() || FilePath(entry->d_name).getExtension() == extension))
             {
                 files.push_back(FilePath(entry->d_name));
             }

source/MaterialXFormat/File.h

@@ -188,7 +188,8 @@ class MX_FORMAT_API FilePath
     bool isDirectory() const;
 
     /// Return a vector of all files in the given directory with the given extension.
-    FilePathVec getFilesInDirectory(const string& extension) const;
+    /// If extension is empty all files are returned.
+    FilePathVec getFilesInDirectory(const string& extension = EMPTY_STRING) const;
 
     /// Return a vector of all directories at or beneath the given path.
     FilePathVec getSubDirectories() const;

source/MaterialXTest/MaterialXFormat/File.cpp

@@ -154,3 +154,51 @@ TEST_CASE("Path normalization test", "[file]")
         REQUIRE((REFERENCE_ABS_PREFIX / path).getNormalized() == (REFERENCE_ABS_PREFIX / REFERENCE_REL_PATH));
     }
 }
+
+TEST_CASE("Get all files in directory", "[file]")
+{
+    mx::FileSearchPath searchPath = mx::getDefaultDataSearchPath();
+
+    mx::FilePath lightsDir = searchPath.find("resources/Lights");
+
+    mx::FilePathVec mtlxFilenames =
+    {
+        "environment_map.mtlx",
+        "goegap_split.mtlx",
+        "san_giuseppe_bridge_split.mtlx",
+        "table_mountain_split.mtlx"
+    };
+
+    mx::FilePathVec hdrFilenames =
+    {
+        "goegap.hdr",
+        "goegap_split.hdr",
+        "san_giuseppe_bridge.hdr",
+        "san_giuseppe_bridge_split.hdr",
+        "table_mountain.hdr",
+        "table_mountain_split.hdr",
+    };
+
+    mx::FilePathVec allFilesnames = hdrFilenames;
+    allFilesnames.insert(allFilesnames.begin(), mtlxFilenames.begin(), mtlxFilenames.end());
+
+    mx::FilePathVec results;
+
+    results = lightsDir.getFilesInDirectory("mtlx");
+    for (const mx::FilePath& filename : results)
+    {
+        REQUIRE(std::find(mtlxFilenames.begin(), mtlxFilenames.end(), filename) != mtlxFilenames.end());
+    }
+
+    results = lightsDir.getFilesInDirectory("hdr");
+    for (const mx::FilePath& filename : results)
+    {
+        REQUIRE(std::find(hdrFilenames.begin(), hdrFilenames.end(), filename) != hdrFilenames.end());
+    }
+
+    results = lightsDir.getFilesInDirectory();
+    for (const mx::FilePath& filename : results)
+    {
+        REQUIRE(std::find(allFilesnames.begin(), allFilesnames.end(), filename) != allFilesnames.end());
+    }
+}