1 files changed, 98 insertions, 0 deletions
diff --git a/lib/nes/common/string-builder.hh b/lib/nes/common/string-builder.hh
new file mode 100644
index 0000000..fda85a4
--- /dev/null
+++ b/lib/nes/common/string-builder.hh
@@ -0,0 +1,98 @@
+#pragma once
+
+#include "nes/common/types.hh"
+#include <string_view>
+
+namespace nes
+{
+	enum class number_format
+	{
+		decimal,
+		hexadecimal,
+		octal,
+		binary,
+	};
+
+	/// Builds a string into a fixed-length buffer.
+	class string_builder
+	{
+		char* buffer_{ nullptr };
+		u32 buffer_length_{ 0 };
+		u32 actual_length_{ 0 };
+		bool is_good_{ true };
+
+		enum class format_arg_type
+		{
+			string,
+			character,
+			signed_integer,
+			unsigned_integer,
+			boolean,
+		};
+
+		struct format_arg
+		{
+			format_arg_type type;
+			union
+			{
+				std::string_view string;
+				char character;
+				i64 signed_integer;
+				u64 unsigned_integer;
+				bool boolean;
+			};
+
+			format_arg() = delete;
+
+			explicit format_arg(char const* v) : type{ format_arg_type::string } { string = v; }
+			explicit format_arg(std::string_view const v) : type{ format_arg_type::string } { string = v; }
+			explicit format_arg(char const v) : type{ format_arg_type::character } { character = v; }
+			explicit format_arg(unsigned char const v) : format_arg{ static_cast<char>(v) } {}
+			explicit format_arg(long long const v) : type{ format_arg_type::signed_integer } { signed_integer = v; }
+			explicit format_arg(unsigned long long const v) : type{ format_arg_type::unsigned_integer } { unsigned_integer = v; }
+			explicit format_arg(short const v) : format_arg{ static_cast<signed long long>(v) } {}
+			explicit format_arg(unsigned short const v) : format_arg{ static_cast<unsigned long long>(v) } {}
+			explicit format_arg(int const v) : format_arg{ static_cast<signed long long>(v) } {}
+			explicit format_arg(unsigned int const v) : format_arg{ static_cast<unsigned long long>(v) } {}
+			explicit format_arg(long const v) : format_arg{ static_cast<signed long long>(v) } {}
+			explicit format_arg(unsigned long const v) : format_arg{ static_cast<unsigned long long>(v) } {}
+			explicit format_arg(bool const v) : type{ format_arg_type::boolean } { boolean = v; }
+		};
+
+	public:
+		explicit string_builder(char* buffer, u32 buffer_length);
+
+		/// Get the resulting string.
+		auto get_result() const -> std::string_view { return std::string_view{ buffer_, actual_length_ }; }
+
+		/// Returns false after an invalid format string or buffer overflow.
+		auto is_good() const -> bool { return is_good_; }
+
+		auto append_char(char) -> string_builder&;
+		auto append_string(std::string_view) -> string_builder&;
+		auto append_int(i64, number_format = number_format::decimal) -> string_builder&;
+		auto append_int(u64, number_format = number_format::decimal) -> string_builder&;
+		auto append_bool(bool) -> string_builder&;
+
+		/// Print a templated string.
+		///
+		/// Placeholders are signified by `{<params>}` where `params` contains optional formatting parameters:
+		///  - for integers either "d" (the default), "x", "o", or "b"
+		///  - for any other type, no parameters are supported.
+		///
+		/// Curly braces can be escaped by repeating them twice like {{this}}.
+		template<typename... Args>
+		auto append_format(std::string_view const fmt, Args... args) -> string_builder&
+		{
+			constexpr u32 arg_count = sizeof...(Args);
+			// Add another argument at the end so we don't have an empty array expression.
+			const format_arg arg_wrappers[arg_count + 1] = { format_arg{ args }..., format_arg(0) };
+
+			return append_format(fmt, arg_wrappers, arg_count);
+		}
+
+	private:
+		auto append_format(std::string_view fmt, format_arg const* args, u32 arg_count) -> string_builder&;
+		auto append_format_arg(format_arg, std::string_view params) -> string_builder&;
+	};
+} // namespace nes
+\ No newline at end of file