fmt.h

Go to the documentation of this file.

 
#ifndef _FMT_H_
#define _FMT_H_
 
#include <any>
#include <cassert>
#include <fmt/core.h>
#include <fmt/format.h>
 
template <>
struct fmt::formatter<std::any> {
    template <typename ParseContext>
    constexpr auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
        // No format string is needed, so just return the end iterator.
        return ctx.end();
    }
 
    template <typename FormatContext>
    auto format(const std::any& value, FormatContext& ctx) -> decltype(ctx.out()) {
        // Use std::any_cast to extract the value from the std::any object.
        if (const auto* x = std::any_cast<const char>(&value)) return fmt::format_to(ctx.out(), "{}", *x);
        else if (const auto* x = std::any_cast<const int>(&value)) return fmt::format_to(ctx.out(), "{}", *x);
        else if (const auto* x = std::any_cast<const unsigned>(&value)) return fmt::format_to(ctx.out(), "{}", *x);
        else if (const auto* x = std::any_cast<const size_t>(&value)) return fmt::format_to(ctx.out(), "{}", *x);
        else if (const auto* x = std::any_cast<const std::string>(&value)) return fmt::format_to(ctx.out(), "{}", *x);
        else if (const auto* x = std::any_cast<const double>(&value)) return fmt::format_to(ctx.out(), "{}", *x);
        else {
            assert(false && "Unknown type in std::any fmt!");
            return fmt::format_to(ctx.out(), "<unknown type>");
        }
    }
};
 
#endif