Add pathname manipulation utilities (#1376)

2 files changed, 241 insertions, 0 deletions

diff --git a/Firestore/core/test/firebase/firestore/util/CMakeLists.txt b/Firestore/core/test/firebase/firestore/util/CMakeLists.txt
index 44a3b61..f540d7c 100644
--- a/Firestore/core/test/firebase/firestore/util/CMakeLists.txt
+++ b/Firestore/core/test/firebase/firestore/util/CMakeLists.txt
@@ -126,6 +126,7 @@ cc_test(
     hashing_test.cc
     iterator_adaptors_test.cc
     ordered_code_test.cc
+    path_test.cc
     status_test.cc
     status_test_util.h
     statusor_test.cc
diff --git a/Firestore/core/test/firebase/firestore/util/path_test.cc b/Firestore/core/test/firebase/firestore/util/path_test.cc
new file mode 100644
index 0000000..be8be1e
--- /dev/null
+++ b/Firestore/core/test/firebase/firestore/util/path_test.cc
@@ -0,0 +1,240 @@
+/*
+ * Copyright 2018 Google
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "Firestore/core/src/firebase/firestore/util/path.h"
+
+#include "gtest/gtest.h"
+
+namespace firebase {
+namespace firestore {
+namespace util {
+
+// There are several potential sources of inspiration for what is correct
+// behavior for these functions.
+//
+// Python: test with
+//
+//   python -c 'import os.path; print(os.path.basename("a/b/c//"))'
+//
+// POSIX shell: test with
+//
+//   dirname "a/b/c//"
+//
+// libc++: std::filesystem does not yet ship with Xcode (as of 9.4). Test with a
+// new (non-default installed) llvm, e.g. llvm-6.0:
+//
+//   brew install llvm
+//   llvm=$(brew --prefix)/opt/llvm
+//   $llvm/bin/clang++ -I$llvm/include -I$llvm/include/c++/v1 -L$llvm/lib \
+//       -Wl,-rpath,$llvm/lib test.cc -lc++experimental && ./a.out
+//
+//   test.cc contains something like:
+//     #include <experimental/filesystem>
+//     #include <iostream>
+//     namespace fs = std::experimental::filesystem;
+//     int main() {
+//       std::cout << fs::path("/a/b/c//").parent_path() << std::endl;
+//     }
+//
+// cppreference: look up example output in functions declared here:
+//   https://en.cppreference.com/w/cpp/filesystem/path
+//
+// This implementation mostly follows python's example:
+//
+//   * It's pretty simple to implement
+//   * POSIX is more complicated than we need
+//   * std::filesystem is still too experimental (as of 2018-06-05)
+
+#define EXPECT_BASENAME_EQ(expected, source)                  \
+  do {                                                        \
+    EXPECT_EQ(std::string{expected}, Path::Basename(source)); \
+  } while (0)
+
+TEST(Path, Basename_NoSeparator) {
+  // POSIX would require all of these to be ".".
+  // python and libc++ agree this is "".
+  EXPECT_BASENAME_EQ("", "");
+  EXPECT_BASENAME_EQ("a", "a");
+  EXPECT_BASENAME_EQ("foo", "foo");
+  EXPECT_BASENAME_EQ(".", ".");
+  EXPECT_BASENAME_EQ("..", "..");
+}
+
+TEST(Path, Basename_LeadingSlash) {
+  EXPECT_BASENAME_EQ("", "/");
+  EXPECT_BASENAME_EQ("", "///");
+  EXPECT_BASENAME_EQ("a", "/a");
+  EXPECT_BASENAME_EQ("a", "//a");
+
+  EXPECT_BASENAME_EQ(".", "/.");
+  EXPECT_BASENAME_EQ("..", "/..");
+  EXPECT_BASENAME_EQ("..", "//..");
+}
+
+TEST(Path, Basename_IntermediateSlash) {
+  EXPECT_BASENAME_EQ("b", "/a/b");
+  EXPECT_BASENAME_EQ("b", "/a//b");
+  EXPECT_BASENAME_EQ("b", "//a/b");
+  EXPECT_BASENAME_EQ("b", "//a//b");
+
+  EXPECT_BASENAME_EQ("b", "//..//b");
+  EXPECT_BASENAME_EQ("b", "//a/./b");
+  EXPECT_BASENAME_EQ("b", "//a/.//b");
+}
+
+TEST(Path, Basename_TrailingSlash) {
+  // python: "a/b//" => ""
+  // POSIX: "a/b//" => "b"
+  // libc++ path::filename(): "a/b//" => "." (cppreference suggests "")
+  EXPECT_BASENAME_EQ("", "/a/");
+  EXPECT_BASENAME_EQ("", "/a///");
+
+  EXPECT_BASENAME_EQ("", "/a/b/");
+  EXPECT_BASENAME_EQ("", "/a/b//");
+  EXPECT_BASENAME_EQ("", "/a//b//");
+  EXPECT_BASENAME_EQ("", "//a//b//");
+}
+
+TEST(Path, Basename_RelativePath) {
+  EXPECT_BASENAME_EQ("b", "a/b");
+  EXPECT_BASENAME_EQ("b", "a//b");
+
+  EXPECT_BASENAME_EQ("b", "..//b");
+  EXPECT_BASENAME_EQ("b", "a/./b");
+  EXPECT_BASENAME_EQ("b", "a/.//b");
+  EXPECT_BASENAME_EQ("b", "a//.//b");
+}
+
+#define EXPECT_DIRNAME_EQ(expected, source)                  \
+  do {                                                       \
+    EXPECT_EQ(std::string{expected}, Path::Dirname(source)); \
+  } while (0)
+
+TEST(Path, Dirname_NoSeparator) {
+  // POSIX would require all of these to be ".".
+  // python and libc++ agree this is "".
+  EXPECT_DIRNAME_EQ("", "");
+  EXPECT_DIRNAME_EQ("", "a");
+  EXPECT_DIRNAME_EQ("", "foo");
+  EXPECT_DIRNAME_EQ("", ".");
+  EXPECT_DIRNAME_EQ("", "..");
+}
+
+TEST(Path, Dirname_LeadingSlash) {
+  // POSIX says all "/".
+  // python starts with "/" but does not strip trailing slashes.
+  // libc++ path::parent_path() considers all of these be "", though
+  // cppreference.com indicates this should be "/" in example output so this is
+  // likely a bug.
+  EXPECT_DIRNAME_EQ("/", "/");
+  EXPECT_DIRNAME_EQ("/", "///");
+  EXPECT_DIRNAME_EQ("/", "/a");
+  EXPECT_DIRNAME_EQ("/", "//a");
+
+  EXPECT_DIRNAME_EQ("/", "/.");
+  EXPECT_DIRNAME_EQ("/", "/..");
+  EXPECT_DIRNAME_EQ("/", "//..");
+}
+
+TEST(Path, Dirname_IntermediateSlash) {
+  EXPECT_DIRNAME_EQ("/a", "/a/b");
+  EXPECT_DIRNAME_EQ("/a", "/a//b");
+  EXPECT_DIRNAME_EQ("//a", "//a/b");
+  EXPECT_DIRNAME_EQ("//a", "//a//b");
+
+  EXPECT_DIRNAME_EQ("//..", "//..//b");
+  EXPECT_DIRNAME_EQ("//a/.", "//a/./b");
+  EXPECT_DIRNAME_EQ("//a/.", "//a/.//b");
+}
+
+TEST(Path, Dirname_TrailingSlash) {
+  // POSIX demands stripping trailing slashes before computing dirname, while
+  // python and libc++ effectively seem to consider the path to contain an empty
+  // path segment there.
+  EXPECT_DIRNAME_EQ("/a", "/a/");
+  EXPECT_DIRNAME_EQ("/a", "/a///");
+
+  EXPECT_DIRNAME_EQ("/a/b", "/a/b/");
+  EXPECT_DIRNAME_EQ("/a/b", "/a/b//");
+  EXPECT_DIRNAME_EQ("/a//b", "/a//b//");
+  EXPECT_DIRNAME_EQ("//a//b", "//a//b//");
+}
+
+TEST(Path, Dirname_RelativePath) {
+  EXPECT_DIRNAME_EQ("a", "a/b");
+  EXPECT_DIRNAME_EQ("a", "a//b");
+
+  EXPECT_DIRNAME_EQ("..", "..//b");
+  EXPECT_DIRNAME_EQ("a/.", "a/./b");
+  EXPECT_DIRNAME_EQ("a/.", "a/.//b");
+  EXPECT_DIRNAME_EQ("a//.", "a//.//b");
+}
+
+TEST(Path, IsAbsolute) {
+  EXPECT_FALSE(Path::IsAbsolute(""));
+  EXPECT_TRUE(Path::IsAbsolute("/"));
+  EXPECT_TRUE(Path::IsAbsolute("//"));
+  EXPECT_TRUE(Path::IsAbsolute("/foo"));
+  EXPECT_FALSE(Path::IsAbsolute("foo"));
+  EXPECT_FALSE(Path::IsAbsolute("foo/bar"));
+}
+
+TEST(Path, Join_Absolute) {
+  EXPECT_EQ("/", Path::Join("/"));
+
+  EXPECT_EQ("/", Path::Join("", "/"));
+  EXPECT_EQ("/", Path::Join("a", "/"));
+  EXPECT_EQ("/b", Path::Join("a", "/b"));
+
+  // Alternate root names should be preserved.
+  EXPECT_EQ("//", Path::Join("a", "//"));
+  EXPECT_EQ("//b", Path::Join("a", "//b"));
+  EXPECT_EQ("///b///", Path::Join("a", "///b///"));
+
+  EXPECT_EQ("/", Path::Join("/", "/"));
+  EXPECT_EQ("/b", Path::Join("/", "/b"));
+  EXPECT_EQ("//b", Path::Join("//host/a", "//b"));
+  EXPECT_EQ("//b", Path::Join("//host/a/", "//b"));
+
+  EXPECT_EQ("/", Path::Join("/", ""));
+  EXPECT_EQ("/a", Path::Join("/", "a"));
+  EXPECT_EQ("/a/b/c", Path::Join("/", "a", "b", "c"));
+  EXPECT_EQ("/a/", Path::Join("/", "a/"));
+  EXPECT_EQ("/.", Path::Join("/", "."));
+  EXPECT_EQ("/..", Path::Join("/", ".."));
+}
+
+TEST(Path, Join_Relative) {
+  EXPECT_EQ("", Path::Join(""));
+
+  EXPECT_EQ("", Path::Join("", "", "", ""));
+  EXPECT_EQ("a/b/c", Path::Join("a/b", "c"));
+  EXPECT_EQ("/c/d", Path::Join("a/b", "/c", "d"));
+  EXPECT_EQ("/c/d", Path::Join("a/b/", "/c", "d"));
+}
+
+TEST(Path, Join_Types) {
+  EXPECT_EQ("a/b", Path::Join(absl::string_view{"a"}, "b"));
+  EXPECT_EQ("a/b", Path::Join(std::string{"a"}, "b"));
+
+  std::string a_string{"a"};
+  EXPECT_EQ("a/b", Path::Join(a_string, "b"));
+  EXPECT_EQ("a", a_string);
+}
+
+}  // namespace util
+}  // namespace firestore
+}  // namespace firebase