cpp-string-utils/include/string_utils/cast.h

//
//  cast.h
//  string-utils
//
//  Created by Sam Jaffe on 2/13/21.
//  Copyright © 2021 Sam Jaffe. All rights reserved.
//

#pragma once

#include <cstdlib>
#include <string>
#include <type_traits>
#include <utility>

#include "any_of.h"

#define cast_number_impl(type, func, ...)       \
bool cast(std::string const &str, type &to) {   \
  char *rval;                             \
  to = func(str.c_str(), &rval, ##__VA_ARGS__); \
  return rval == str.c_str() + str.length();    \
}

namespace string_utils {

template <typename T, typename = std::enable_if_t<std::is_constructible<T, std::string const &>{}>>
bool cast(std::string const &str, std::string &to) { to = T(str); return true; }

cast_number_impl(long, std::strtol, 10)
cast_number_impl(long long, std::strtoll, 10)
cast_number_impl(float, std::strtof)
cast_number_impl(double, std::strtod)
cast_number_impl(long double, std::strtold)

bool cast(std::string const &str, int &to) {
  long tmp;
  bool rval = cast(str, tmp);
  to = static_cast<int>(tmp);
  return rval && tmp == static_cast<long>(to);
}

bool cast(std::string const &str, bool &to) {
  if (any_of(str, "true", "TRUE", "YES", "1")) {
    to = true;
    return true;
  } else if (any_of(str, "false", "FALSE", "NO", "0")) {
    to = false;
    return true;
  }
  return false;
}

template <typename T>
auto cast(std::string const &str) {
  using string_utils::cast;
  std::pair<T, bool> rval;
  rval.second = cast(str, rval.first);
  return rval;
}

}