From 2fe8f689fd500874e9dc2d49dc976797de1db7be Mon Sep 17 00:00:00 2001
From: Thomas Otto <thomas.otto@pdv-fs.de>
Date: Wed, 30 Oct 2019 11:21:00 +0100
Subject: [PATCH] Add and test get_extension()

Works as a replacement for the legacy util function.
---
 src/Util.cpp           | 24 +++++++++++++++++++++++-
 src/Util.hpp           |  4 ++++
 unittest/test_Util.cpp | 15 +++++++++++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/Util.cpp b/src/Util.cpp
index 42ba9d23c..e9f0b57d4 100644
--- a/src/Util.cpp
+++ b/src/Util.cpp
@@ -24,6 +24,8 @@
 #include <algorithm>
 #include <fstream>
 
+using nonstd::string_view;
+
 namespace {
 
 void
@@ -40,7 +42,7 @@ get_cache_files_internal(const std::string& dir,
   std::vector<std::string> directories;
   dirent* de;
   while ((de = readdir(d))) {
-    nonstd::string_view name(de->d_name);
+    string_view name(de->d_name);
     if (name == "" || name == "." || name == ".." || name == "CACHEDIR.TAG"
         || name == "stats" || name.starts_with(".nfs")) {
       continue;
@@ -139,6 +141,26 @@ dir_name(nonstd::string_view path)
   return n == 0 ? "/" : path.substr(0, n);
 }
 
+nonstd::string_view
+get_extension(nonstd::string_view path)
+{
+#ifndef _WIN32
+  const char stop_at_chars[] = "./";
+#else
+  const char stop_at_chars[] = "./\\";
+#endif
+  size_t pos = path.find_last_of(stop_at_chars);
+  if (pos == string_view::npos || path.at(pos) == '/') {
+    return string_view();
+#ifdef _WIN32
+  } else if (path.at(pos) == '\\') {
+    return string_view();
+#endif
+  } else {
+    return path.substr(pos);
+  }
+}
+
 nonstd::string_view
 get_truncated_base_name(nonstd::string_view path, size_t max_length)
 {
diff --git a/src/Util.hpp b/src/Util.hpp
index f8876343a..f86c7c1de 100644
--- a/src/Util.hpp
+++ b/src/Util.hpp
@@ -41,6 +41,10 @@ typedef std::function<void(const std::string& /*dir_path*/,
 // Get base name of path.
 nonstd::string_view base_name(nonstd::string_view path);
 
+// Return the file extension (including the dot) as a view into `path`.
+// If `path` has no file extension, an empty string_view is returned.
+nonstd::string_view get_extension(nonstd::string_view path);
+
 // Return a shortened view into the base name of `path``. This view starts at
 // the beginning of the base name and ends at either the position the first dot,
 // or `max_length`, or the length of the base name, whichever is the shortest.
diff --git a/unittest/test_Util.cpp b/unittest/test_Util.cpp
index eb031a639..5a500e1d0 100644
--- a/unittest/test_Util.cpp
+++ b/unittest/test_Util.cpp
@@ -32,6 +32,21 @@ TEST_CASE("Util::base_name")
   CHECK(Util::base_name("/foo/bar/f.txt") == "f.txt");
 }
 
+TEST_CASE("Util::get_extension")
+{
+  CHECK(Util::get_extension("") == "");
+  CHECK(Util::get_extension(".") == ".");
+  CHECK(Util::get_extension("...") == ".");
+  CHECK(Util::get_extension("foo") == "");
+  CHECK(Util::get_extension("/") == "");
+  CHECK(Util::get_extension("/foo") == "");
+  CHECK(Util::get_extension("/foo/bar/f") == "");
+  CHECK(Util::get_extension("f.txt") == ".txt");
+  CHECK(Util::get_extension("f.abc.txt") == ".txt");
+  CHECK(Util::get_extension("/foo/bar/f.txt") == ".txt");
+  CHECK(Util::get_extension("/foo/bar/f.abc.txt") == ".txt");
+}
+
 TEST_CASE("Util:get_truncated_base_name")
 {
   CHECK(Util::get_truncated_base_name("", 5) == "");
-- 
2.47.2