string_format.h

Go to the documentation of this file.

#pragma once
 
#include <string>
#include <string_view>
#if USE_STD_FORMAT
#include <format>
#else
#include "internal.h"
#endif
 
namespace kuzu {
namespace common {
 
#if USE_STD_FORMAT
 
template<typename... Args>
inline std::string stringFormat(std::format_string<Args...> format, Args&&... args) {
    return std::format(format, std::forward<Args>(args)...);
}
 
#else
 
namespace string_format_detail {
#define MAP_STD_TO_STRING(typ)                                                                     \
    inline std::string map(typ v) {                                                                \
        return std::to_string(v);                                                                  \
    }
 
MAP_STD_TO_STRING(short)
MAP_STD_TO_STRING(unsigned short)
MAP_STD_TO_STRING(int)
MAP_STD_TO_STRING(unsigned int)
MAP_STD_TO_STRING(long)
MAP_STD_TO_STRING(unsigned long)
MAP_STD_TO_STRING(long long)
MAP_STD_TO_STRING(unsigned long long)
MAP_STD_TO_STRING(float)
MAP_STD_TO_STRING(double)
#undef MAP_STD_TO_STRING
 
#define MAP_SELF(typ)                                                                              \
    inline typ map(typ v) {                                                                        \
        return v;                                                                                  \
    }
MAP_SELF(const char*);
// Also covers std::string
MAP_SELF(std::string_view)
 
// Chars are mapped to themselves, but signed char and unsigned char (which are used for int8_t and
// uint8_t respectively), need to be cast to be properly output as integers. This is consistent with
// fmt's behavior.
MAP_SELF(char)
inline std::string map(signed char v) {
    return std::to_string(int(v));
}
inline std::string map(unsigned char v) {
    return std::to_string(unsigned(v));
}
#undef MAP_SELF
 
template<typename... Args>
inline void stringFormatHelper(std::string& ret, std::string_view format, Args&&... args) {
    size_t bracket = format.find('{');
    if (bracket == std::string_view::npos) {
        ret += format;
        return;
    }
    ret += format.substr(0, bracket);
    if (format.substr(bracket, 4) == "{{}}") {
        // Escaped {}.
        ret += "{}";
        return stringFormatHelper(ret, format.substr(bracket + 4), std::forward<Args>(args)...);
    } else if (format.substr(bracket, 2) == "{}") {
        // Formatted {}.
        throw InternalException("Not enough values for string_format.");
    }
    // Something else.
    ret.push_back('{');
    return stringFormatHelper(ret, format.substr(bracket + 1), std::forward<Args>(args)...);
}
 
template<typename Arg, typename... Args>
inline void stringFormatHelper(std::string& ret, std::string_view format, Arg&& arg,
    Args&&... args) {
    size_t bracket = format.find('{');
    if (bracket == std::string_view::npos) {
        throw InternalException("Too many values for string_format.");
    }
    ret += format.substr(0, bracket);
    if (format.substr(bracket, 4) == "{{}}") {
        // Escaped {}.
        ret += "{}";
        return stringFormatHelper(ret, format.substr(bracket + 4), std::forward<Arg>(arg),
            std::forward<Args>(args)...);
    } else if (format.substr(bracket, 2) == "{}") {
        // Formatted {}.
        ret += map(arg);
        return stringFormatHelper(ret, format.substr(bracket + 2), std::forward<Args>(args)...);
    }
    // Something else.
    ret.push_back('{');
    return stringFormatHelper(ret, format.substr(bracket + 1), std::forward<Arg>(arg),
        std::forward<Args>(args)...);
}
} // namespace string_format_detail
 
// Formats `args` according to `format`. Accepts {} for formatting the argument and {{}} for
// a literal {}. Formatting is done with std::ostream::operator<<.
template<typename... Args>
inline std::string stringFormat(std::string_view format, Args&&... args) {
    std::string ret;
    ret.reserve(32); // Optimistic pre-allocation.
    string_format_detail::stringFormatHelper(ret, format, std::forward<Args>(args)...);
    return ret;
}
 
#endif
 
} // namespace common
} // namespace kuzu