Fix maximum value check for parsing numbers from format strings

2 files changed, 8 insertions, 5 deletions

diff --git a/include/cxxformat/core.hpp b/include/cxxformat/core.hpp
index 2a78b26..acf8613 100644
--- a/include/cxxformat/core.hpp
+++ b/include/cxxformat/core.hpp
@@ -189,7 +189,7 @@ namespace format {
 	}
 
 	template<std::unsigned_integral T = unsigned int>
-	constexpr std::pair<std::optional<T>, std::size_t> parseNumber(std::string_view s, std::size_t pos)
+	constexpr std::pair<optional_int<T>, std::size_t> parseNumber(std::string_view s, std::size_t pos)
 	{
 		if (pos >= s.size())
 		{
@@ -202,7 +202,7 @@ namespace format {
 			return {std::nullopt, pos};
 		}
 
-		constexpr auto max = std::numeric_limits<T>::max();
+		constexpr auto max = optional_int<T>::max;
 
 		T val{*d};
 		auto p = pos + 1;
@@ -225,12 +225,12 @@ namespace format {
 	}
 
 	template<std::unsigned_integral T = unsigned int>
-	constexpr std::pair<std::optional<T>, std::size_t> parseNumberWithMessage(std::string_view s, std::size_t pos, std::string_view numberName)
+	constexpr std::pair<optional_int<T>, std::size_t> parseNumberWithMessage(std::string_view s, std::size_t pos, std::string_view numberName)
 	{
 		try {
 			return parseNumber<T>(s, pos);
 		} catch(const std::out_of_range&) {
-			throw std::out_of_range{std::string{numberName} + " is too big; maximum is " + std::to_string(std::numeric_limits<T>::max())};
+			throw std::out_of_range{std::string{numberName} + " is too big; maximum is " + std::to_string(optional_int<T>::max)};
 		}
 	}
 
diff --git a/include/cxxformat/helpers.hpp b/include/cxxformat/helpers.hpp
index 73cb0be..c713835 100644
--- a/include/cxxformat/helpers.hpp
+++ b/include/cxxformat/helpers.hpp
@@ -226,7 +226,7 @@ struct optional_int {
 
 	constexpr optional_int() noexcept : val{emptyVal} {}
 	constexpr optional_int(std::nullopt_t) noexcept : val{emptyVal} {}
-	constexpr optional_int(T val) noexcept : val{val} {}
+	constexpr optional_int(T val) noexcept : val{val} { assert(val != emptyVal); }
 	constexpr optional_int(const optional_int&) noexcept = default;
 	template<std::convertible_to<T> U>
 	constexpr optional_int(const optional_int<U>& other) noexcept : val{other ? other.val : emptyVal} {}
@@ -257,4 +257,7 @@ struct optional_int {
 	constexpr T& operator*() noexcept { return val; }
 	constexpr T operator*() const noexcept { return val; }
 	constexpr T value_or(T fallback) const noexcept { return empty() ? fallback : val; }
+
+	static inline constexpr T max{std::signed_integral<T> ? std::numeric_limits<T>::max() : emptyVal - 1};
+	static inline constexpr T min{std::numeric_limits<T>::min() + (std::signed_integral<T> ? 1 : 0)};
 };