Add bool formatter

1 files changed, 49 insertions, 0 deletions

diff --git a/include/cxxformat/formatters.hpp b/include/cxxformat/formatters.hpp
index 264cc52..03af08e 100644
--- a/include/cxxformat/formatters.hpp
+++ b/include/cxxformat/formatters.hpp
@@ -233,6 +233,55 @@ namespace format {
 		}
 	};
 
+	template<>
+	struct formatter<bool> {
+		static constexpr format_specifier delegateSpec(format_specifier from) noexcept
+		{
+			from.conversion = 'u';
+			return from;
+		}
+
+		using delegated_formatter = formatter<std::uint8_t>;
+
+		static constexpr void format(const format_output auto& out, bool v, format_specifier spec, optional_int<std::size_t> minWidth, optional_int<std::size_t> precision)
+		{
+			if (spec.conversion == 'u')
+			{
+				return delegated_formatter::format(out, v ? 1 : 0, delegateSpec(spec), minWidth, precision);
+			}
+			else
+			{
+				const auto val = v ? std::string_view{"true"} : std::string_view{"false"};
+				formatPadded(out, val, ' ', spec.flags.leftJustified, minWidth);
+			}
+		}
+
+		static constexpr void conversionSupported(format_specifier spec)
+		{
+			const auto conv = spec.conversion;
+			simpleConversionSpecifierCheck("usv", conv, "bool");
+			noAlternative(spec.flags.alternative, "bools");
+			noSignFlags(spec.addSign, "bools");
+
+			if (conv == 'u')
+			{
+				delegated_formatter::conversionSupported(delegateSpec(spec));
+			}
+			else
+			{
+				if (spec.precision)
+				{
+					throw std::invalid_argument{"Specifying a precision for bool is only supported with %u conversion"};
+				}
+				if (spec.padding != ' ')
+				{
+					throw std::invalid_argument{"Zero padding (‘0’ flag) for bool is only supported for %u conversion"};
+				}
+			}
+		}
+	};
+
+
 	// NOTE: Difference to printf: uses std::to_chars’ minimal width for exact representation when no precision is specified instead of default precision of 6
 	template<std::floating_point T>
 	struct formatter<T> {