improve error handling

1 files changed, 47 insertions, 21 deletions

diff --git a/nihil.ucl/integer.cc b/nihil.ucl/integer.cc
index 16328d4..f4f08ef 100644
--- a/nihil.ucl/integer.cc
+++ b/nihil.ucl/integer.cc
@@ -6,36 +6,65 @@ module;
 
 #include <compare>
 #include <cstdlib>
+#include <expected>
+#include <system_error>
 
 #include <ucl.h>
 
 module nihil.ucl;
 
+import nihil;
+
 namespace nihil::ucl {
 
+integer::integer()
+	: integer(0)
+{
+}
+
+integer::integer(contained_type value)
+	: integer(noref, [&] {
+		auto *uobj = ::ucl_object_fromint(value);
+		if (uobj == nullptr)
+			throw std::system_error(
+				std::make_error_code(std::errc(errno)));
+		return uobj;
+	}())
+{
+}
+
 integer::integer(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 != integer::ucl_type)
+			throw type_mismatch(integer::ucl_type, actual_type);
+		return uobj;
+	}())
 {
-	if (type() != ucl_type)
-		throw type_mismatch(ucl_type, type());
 }
 
 integer::integer(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 != integer::ucl_type)
+			throw type_mismatch(integer::ucl_type, actual_type);
+		return uobj;
+	}())
 {
-	if (type() != ucl_type)
-		throw type_mismatch(ucl_type, type());
 }
 
-integer::integer()
-	: integer(0)
-{}
-
-integer::integer(contained_type value)
-	: object(noref, ::ucl_object_fromint(value))
+auto make_integer(integer::contained_type value)
+	-> std::expected<integer, error>
 {
-	if (_object == nullptr)
-		throw error("failed to create UCL object");
+	auto *uobj = ::ucl_object_fromint(value);
+	if (uobj == nullptr)
+		return std::unexpected(error(
+			errc::failed_to_create_object,
+			error(std::errc(errno))));
+
+	return integer(noref, uobj);
 }
 
 auto integer::value(this integer const &self) -> contained_type
@@ -49,26 +78,23 @@ auto integer::value(this integer const &self) -> contained_type
 	std::abort();
 }
 
-auto operator== (integer const &a, integer const &b)
--> bool
+auto operator== (integer const &a, integer const &b) -> bool
 {
 	return a.value() == b.value();
 }
 
-auto operator<=> (integer const &a, integer const &b)
--> std::strong_ordering
+auto operator<=> (integer const &a, integer const &b) -> std::strong_ordering
 {
 	return a.value() <=> b.value();
 }
 
-auto operator== (integer const &a, integer::contained_type b)
--> bool
+auto operator== (integer const &a, integer::contained_type b) -> bool
 {
 	return a.value() == b;
 }
 
 auto operator<=> (integer const &a, integer::contained_type b)
--> std::strong_ordering
+	-> std::strong_ordering
 {
 	return a.value() <=> b;
 }