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#pragma once
#include "format_arg.h"
#include <util/generic/strbuf.h>
#include <array>
#include <string_view>
namespace NYT::NDetail {
////////////////////////////////////////////////////////////////////////////////
struct TFormatAnalyser
{
public:
// TODO(arkady-e1ppa): Until clang-19 consteval functions
// defined out of line produce symbols in rare cases
// causing linker to crash.
template <class... TArgs>
static consteval void ValidateFormat(std::string_view fmt)
{
DoValidateFormat<TArgs...>(fmt);
}
private:
// Non-constexpr function call will terminate compilation.
// Purposefully undefined and non-constexpr/consteval
template <class T>
static void CrashCompilerNotFormattable(std::string_view /*msg*/)
{ /*Suppress "internal linkage but undefined" warning*/ }
static void CrashCompilerNotEnoughArguments(std::string_view /*msg*/)
{ }
static void CrashCompilerTooManyArguments(std::string_view /*msg*/)
{ }
static void CrashCompilerWrongTermination(std::string_view /*msg*/)
{ }
static void CrashCompilerMissingTermination(std::string_view /*msg*/)
{ }
static void CrashCompilerWrongFlagSpecifier(std::string_view /*msg*/)
{ }
static consteval bool Contains(std::string_view sv, char symbol)
{
return sv.find(symbol) != std::string_view::npos;
}
struct TSpecifiers
{
std::string_view Conversion;
std::string_view Flags;
};
template <class TArg>
static consteval auto GetSpecifiers()
{
if constexpr (!CFormattable<TArg>) {
CrashCompilerNotFormattable<TArg>("Your specialization of TFormatArg is broken");
}
return TSpecifiers{
.Conversion = std::string_view{
std::data(TFormatArg<TArg>::ConversionSpecifiers),
std::size(TFormatArg<TArg>::ConversionSpecifiers)},
.Flags = std::string_view{
std::data(TFormatArg<TArg>::FlagSpecifiers),
std::size(TFormatArg<TArg>::FlagSpecifiers)},
};
}
static constexpr char IntroductorySymbol = '%';
template <class... TArgs>
static consteval void DoValidateFormat(std::string_view format)
{
std::array<std::string_view, sizeof...(TArgs)> markers = {};
std::array<TSpecifiers, sizeof...(TArgs)> specifiers{GetSpecifiers<TArgs>()...};
int markerCount = 0;
int currentMarkerStart = -1;
for (int index = 0; index < std::ssize(format); ++index) {
auto symbol = format[index];
// Parse verbatim text.
if (currentMarkerStart == -1) {
if (symbol == IntroductorySymbol) {
// Marker maybe begins.
currentMarkerStart = index;
}
continue;
}
// NB: We check for %% first since
// in order to verify if symbol is a specifier
// we need markerCount to be within range of our
// specifier array.
if (symbol == IntroductorySymbol) {
if (currentMarkerStart + 1 != index) {
// '%a% detected'
CrashCompilerWrongTermination("You may not terminate flag sequence other than %% with \'%\' symbol");
return;
}
// '%%' detected --- skip
currentMarkerStart = -1;
continue;
}
// We are inside of marker.
if (markerCount == std::ssize(markers)) {
// To many markers
CrashCompilerNotEnoughArguments("Number of arguments supplied to format is smaller than the number of flag sequences");
return;
}
if (Contains(specifiers[markerCount].Conversion, symbol)) {
// Marker has finished.
markers[markerCount]
= std::string_view(format.begin() + currentMarkerStart, index - currentMarkerStart + 1);
currentMarkerStart = -1;
++markerCount;
continue;
}
if (!Contains(specifiers[markerCount].Flags, symbol)) {
CrashCompilerWrongFlagSpecifier("Symbol is not a valid flag specifier; See FlagSpecifiers");
}
}
if (currentMarkerStart != -1) {
// Runaway marker.
CrashCompilerMissingTermination("Unterminated flag sequence detected; Use \'%%\' to type plain %");
return;
}
if (markerCount < std::ssize(markers)) {
// Missing markers.
CrashCompilerTooManyArguments("Number of arguments supplied to format is greater than the number of flag sequences");
return;
}
// TODO(arkady-e1ppa): Consider per-type verification
// of markers.
}
};
////////////////////////////////////////////////////////////////////////////////
} // namespace NYT::NDetail
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