improve error handling

1 files changed, 60 insertions, 12 deletions

diff --git a/nihil.ucl/string.cc b/nihil.ucl/string.cc
index d2f4618..0fc9808 100644
--- a/nihil.ucl/string.cc
+++ b/nihil.ucl/string.cc
@@ -5,26 +5,62 @@
 module;
 
 #include <cstdlib>
+#include <expected>
+#include <iosfwd>
 #include <string>
+#include <system_error>
 
 #include <ucl.h>
 
 module nihil.ucl;
 
+import nihil;
+
 namespace nihil::ucl {
 
+auto make_string() -> std::expected<string, error>
+{
+	return make_string(std::string_view(""));
+}
+
+auto make_string(char const *s) -> std::expected<string, error>
+{
+	return make_string(std::string_view(s));
+}
+
+auto make_string(std::string_view s) -> std::expected<string, error>
+{
+	auto *uobj = ::ucl_object_fromstring_common(
+			s.data(), s.size(), UCL_STRING_RAW);
+
+	if (uobj == nullptr)
+		return std::unexpected(error(
+			errc::failed_to_create_object,
+			error(std::errc(errno))));
+
+	return string(noref, uobj);
+}
+
 string::string(ref_t, ::ucl_object_t const *uobj)
-	: object(nihil::ucl::ref, uobj)
+	: object(nihil::ucl::ref, [&] {
+		auto actual_type = static_cast<object_type>(
+					::ucl_object_type(uobj));
+		if (actual_type != string::ucl_type)
+			throw type_mismatch(string::ucl_type, actual_type);
+		return uobj;
+	}())
 {
-	if (type() != ucl_type)
-		throw type_mismatch(ucl_type, type());
 }
 
 string::string(noref_t, ::ucl_object_t *uobj)
-	: object(noref, uobj)
+	: object(nihil::ucl::noref, [&] {
+		auto actual_type = static_cast<object_type>(
+					::ucl_object_type(uobj));
+		if (actual_type != string::ucl_type)
+			throw type_mismatch(string::ucl_type, actual_type);
+		return uobj;
+	}())
 {
-	if (type() != ucl_type)
-		throw type_mismatch(ucl_type, type());
 }
 
 string::string()
@@ -32,13 +68,20 @@ string::string()
 {}
 
 string::string(std::string_view value)
-	: object(nihil::ucl::ref, 
-		 ::ucl_object_fromstring_common(
-			value.data(), value.size(),
-			UCL_STRING_RAW))
+	: string(noref, [&] {
+		auto *uobj = ::ucl_object_fromstring_common(
+				value.data(), value.size(), UCL_STRING_RAW);
+		if (uobj == nullptr)
+			throw std::system_error(
+				std::make_error_code(std::errc(errno)));
+		return uobj;
+	}())
+{
+}
+
+string::string(char const *value)
+	: string(std::string_view(value))
 {
-	if (_object == nullptr)
-		throw error("failed to create UCL object");
 }
 
 auto string::value(this string const &self) -> contained_type
@@ -136,4 +179,9 @@ auto operator<=>(string const &lhs, char const *rhs)
 	return lhs <=> std::string_view(rhs);
 }
 
+auto operator<<(std::ostream &strm, string const &s) -> std::ostream &
+{
+	return strm << s.value();
+}
+
 } // namespace nihil::ucl