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#include "nes/common/containers/string-builder.hh"
namespace nes
{
string_builder::string_builder(span<char> const buffer)
: buffer_{ buffer }
{
}
auto string_builder::append_char(char const value) -> status
{
if (length_ == buffer_.get_length()) { return status::error_buffer_overflow; }
buffer_[length_] = value;
length_ += 1;
return status::success;
}
auto string_builder::append_string(std::string_view const value) -> status
{
auto copy = *this;
for (auto const c : value)
{
if (auto const s = copy.append_char(c); s != status::success) { return s; }
}
*this = copy;
return status::success;
}
auto string_builder::append_int(i64 value, number_format const format) -> status
{
auto copy = *this;
if (value < 0)
{
if (auto const s = copy.append_char('-'); s != status::success) { return s; }
value += 1; // to prevent lossy conversion to unsigned
auto abs_value = static_cast<u64>(-value);
abs_value += 1; // to correct the previous offset
if (auto const s = copy.append_int(abs_value, format); s != status::success) { return s; }
}
else
{
if (auto const s = copy.append_int(static_cast<u64>(value), format); s != status::success) { return s; }
}
*this = copy;
return status::success;
}
auto string_builder::append_int(u64 value, number_format const format) -> status
{
constexpr auto max_string_length = u32{ 64 }; // worst case is a 64-bit integer in binary representation
constexpr auto digits = "0123456789abcdef";
auto copy = *this;
auto base = u64{ 10 };
auto prefix = "";
switch (format)
{
case number_format::binary:
prefix = "0b";
base = 2;
break;
case number_format::octal:
prefix = "0";
base = 8;
break;
case number_format::decimal:
break;
case number_format::hexadecimal:
prefix = "0x";
base = 16;
break;
}
if (auto const s = copy.append_string(prefix); s != status::success) { return s; }
char buf[max_string_length + 1] = {}; // null-terminated
auto pos = max_string_length;
// Go through each digit in reverse order by continuously dividing the integer by the base.
while (value)
{
pos--;
buf[pos] = digits[value % base]; // Convert digit to char representation
value /= base;
}
if (pos == max_string_length)
{
// Special case 0 would not print any character otherwise.
pos--;
buf[pos] = '0';
}
if (const auto s = copy.append_string(&buf[pos]); s != status::success) { return s; }
*this = copy;
return status::success;
}
auto string_builder::append_bool(bool const value) -> status
{
return append_string(value ? "true" : "false");
}
auto string_builder::append_format(std::string_view const fmt, format_arg const* args, u32 const arg_count) -> status
{
auto copy = *this;
// Go through the format string, inserting the arguments for the templates as necessary.
auto current_arg = u32{ 0 };
for (auto i = u32{ 0 }; i < fmt.length(); ++i)
{
if (fmt[i] == '{')
{
i += 1;
if (fmt[i] == '{') {
// escaped '{'
if (auto const s = copy.append_char('{'); s != status::success) { return s; }
}
else
{
// start of template
auto const params = &fmt[i]; // remember start position
auto params_length = u32{ 0 };
// skip to the end of the template
while (fmt[i] && fmt[i] != '}')
{
params_length++;
i++;
}
if (fmt[i] != '}')
{
// unmatched '{'
return status::error_invalid_format_string;
}
// end of template
auto const p = std::string_view{ params, params_length };
if (current_arg < arg_count)
{
if (auto const s = copy.append_format_arg(args[current_arg], p); s != status::success) { return s; }
current_arg += 1;
}
else
{
// missing argument in parameter pack
return status::error_invalid_format_string;
}
}
}
else if (fmt[i] == '}')
{
i += 1;
if (fmt[i] == '}')
{
// escaped '}'
if (auto const s = copy.append_char('}'); s != status::success) { return s; }
}
else
{
// unmatched '}'
return status::error_invalid_format_string;
}
}
else
{
// normal character in the template string
if (auto const s = copy.append_char(fmt[i]); s != status::success) { return s; }
}
}
if (current_arg < arg_count)
{
// not all supplied arguments were used
return status::error_invalid_format_string;
}
*this = copy;
return status::success;
}
auto string_builder::append_format_arg(format_arg const arg, std::string_view const params) -> status
{
auto const parse_params = [&]
{
if (!params.empty())
{
return status::error_invalid_format_string;
}
return status::success;
};
auto const parse_params_integer = [&](number_format& out_format)
{
if (params.empty() || params == "d")
{
out_format = number_format::decimal;
}
else if (params == "x")
{
out_format = number_format::hexadecimal;
}
else if (params == "o")
{
out_format = number_format::octal;
}
else if (params == "b")
{
out_format = number_format::binary;
}
else
{
return status::error_invalid_format_string;
}
return status::success;
};
switch (arg.type)
{
case format_arg_type::string:
{
if (auto const s = parse_params(); s != status::success) { return s; }
return append_string(arg.string);
}
case format_arg_type::character:
{
if (auto const s = parse_params(); s != status::success) { return s; }
return append_char(arg.character);
}
case format_arg_type::signed_integer:
{
auto format = number_format{};
if (auto const s = parse_params_integer(format); s != status::success) { return s; }
return append_int(arg.signed_integer, format);
}
case format_arg_type::unsigned_integer:
{
auto format = number_format{};
if (auto const s = parse_params_integer(format); s != status::success) { return s; }
return append_int(arg.unsigned_integer, format);
}
case format_arg_type::boolean:
{
if (auto const s = parse_params(); s != status::success) { return s; }
return append_bool(arg.character);
}
}
return status::error_invalid_format_string;
}
} // namespace nes
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