[WIP] Introduce a utility function to transform a path into a URI

src/core/uri/include/sourcemeta/core/uri.h

@@ -10,6 +10,7 @@
 // NOLINTEND(misc-include-cleaner)
 
 #include <cstdint>     // std::uint32_t
+#include <filesystem>  // std::filesystem
 #include <istream>     // std::istream
 #include <memory>      // std::unique_ptr
 #include <optional>    // std::optional
@@ -437,6 +438,10 @@ class SOURCEMETA_CORE_URI_EXPORT URI {
 #endif
 };
 
+// @ingroup uri
+// TODO: test & document
+auto to_uri(const std::filesystem::path &path) -> URI;
+
 } // namespace sourcemeta::core
 
 #endif

src/core/uri/uri.cc

@@ -6,7 +6,7 @@
 #include <cstdint>   // std::uint32_t
 #include <istream>   // std::istream
 #include <optional>  // std::optional
-#include <sstream>   // std::ostringstream
+#include <sstream>   // std::ostringstream, std::istringstream
 #include <stdexcept> // std::length_error, std::runtime_error
 #include <string>    // std::stoul, std::string, std::tolower
 #include <tuple>     // std::tie
@@ -634,4 +634,28 @@ auto URI::operator<(const URI &other) const noexcept -> bool {
                   other.path_, other.query_, other.fragment_);
 }
 
+auto to_uri(const std::filesystem::path &path) -> URI {
+  // URI representation of paths is only valid for absolute paths
+  assert(path.is_absolute());
+
+  // Get the path always with forward slashes
+  // https://en.cppreference.com/w/cpp/filesystem/path/generic_string.html
+  const auto unix_path{path.generic_string()};
+  std::ostringstream result;
+  if (unix_path.empty() || unix_path.front() != '/') {
+    result << '/';
+  }
+
+  result << unix_path;
+
+  // TODO: This whole dance is because we don't
+  // allow setting a scheme on an existing URI
+  URI temp{result.str()};
+  temp.canonicalize();
+  std::ostringstream final_result;
+  final_result << "file://";
+  final_result << temp.recompose();
+  return URI{final_result.str()};
+}
+
 } // namespace sourcemeta::core

test/uri/CMakeLists.txt

@@ -4,6 +4,7 @@ sourcemeta_googletest(NAMESPACE sourcemeta PROJECT core NAME uri
     uri_fragment_test.cc
     uri_host_test.cc
     uri_path_test.cc
+    uri_path_to_uri_test.cc
     uri_parse_test.cc
     uri_port_test.cc
     uri_scheme_test.cc

test/uri/uri_path_to_uri_test.cc

@@ -0,0 +1,16 @@
+#include <gtest/gtest.h>
+
+#include <sourcemeta/core/uri.h>
+
+TEST(URI_path_to_uri, unix_absolute) {
+  const std::filesystem::path example{"/foo/bar/baz"};
+  const auto uri{sourcemeta::core::to_uri(example)};
+  EXPECT_EQ(uri.recompose(), "file:///foo/bar/baz");
+}
+
+TEST(URI_path_to_uri, unix_absolute_other_characters) {
+  const std::filesystem::path example{"/foo bar/bar?"};
+  const auto uri{sourcemeta::core::to_uri(example)};
+  // TODO: Escape
+  EXPECT_EQ(uri.recompose(), "file:///foo bar/bar?");
+}