to.cpp

brings type conversion features in modern C++. Online Preview

to::_types

std::cout<< to::_int("4132"); // 4132
std::cout<< to::_unsigned_int("9999999999999999999999999999"); // out_of_range exception

• Supported Types
  • signed/unsigned int
  • signed/unsigned long
  • 나중에 추가

to::_string

Primitive types

int v = 1234;
std::cout<< to::_string(v); // 1234
std::cout<< to::_string(4.44f); // 4.44

bool b = true;
std::cout<< to::_string(b); // true

// Pointers will be converted into `Typename + Address`.
int *ptr = &v;
std::cout<< to::_string(v); // #<int * 0000abcd>

// nullptr
std::cout<< to::_string(nullptr); // #<std::nullptr_t 00000000>

// char *, const char *, char [], const char[]
//   types will be treated as 'String' instead of 'Pointer'.
char *s = "hello world";
std::cout<< to::_string(s); // hello world

STL Containers

vector

std::vector<int> v({1,2,3,4});
std::cout<< to::_string(v); // [1, 2, 3, 4]

map

std::map<std::string, std::string> m({
  {"name", "park"},
  {"chicken", "good"}});
std::cout<< to::_string(m); // {name : park, chicken : good}

map + vector

std::map<std::string, std::vector<std::string>> m2({
  {"fruits", {"apple", "banana", "orange"}},
	{"colors", {"yellow", "red", "blue"}}});
std::cout<< to::_string(m2); // {fruits : [apple, banana, orange], colors : [yellow, red, blue]}

misc

std::string str = "hello world";
std::cout<< to::_string(str); // hello world

std::cout<< to::_string({1,2,3,4}); // [1, 2, 3, 4]
std::cout<< to::_string({{1,2}, {3,4}}); // not implemented yet

std::initializer_list<std::initializer_list<int>> l({{1,2}, {3,4}});
std::cout<< to::_string(l); // [[1, 2], [3, 4]]

Custom Classes
You can make a custom string converter for your class by implementing the to_string method.

class Foo{
public:
  int v;
  
  std::string to_string() const{
    return "#<Foo v:" + to::_string(v) + ">";
  }
}

Foo f;
f.v = 15;

std::cout<< to::_string(f); // #<Foo v:15>

ToString Generator
It also have a convenient macro which auto-implements to_string method.

class weapon {
public:
  CREATE_TO_STRING(damage, level)

  int damage = 123;
  int level = 1;
};
class item {
public:

CREATE_TO_STRING(name, qty)

  std::string name;
  int qty = 5;
};
class player {
public:
  CREATE_TO_STRING(hp, weapon, inventory)

  int hp = 100;
  weapon weapon;
  std::vector<item> inventory;
  int a_secret_one = 1234;
};

player a;
item item1, item2;
item1.name = "SWORD";
item2.name = "CHICKEN";
a.inventory.push_back(item1);
a.inventory.push_back(item2);
printf("%s\n", a.to_string().c_str());

출력 결과물 (가독성을 위해 수동으로 줄바꿈 하였습니다, 실제 결과는 줄바꿈이 없습니다.)

#<class player
inventory : [
  #<class item  qty : 5, name : SWORD>,
  #<class item  qty : 5, name : CHICKEN>], 
weapon : #<class weapon  level : 1, damage : 123>,
hp : 100>

If no conversion is available, type name and address value will be returned.

Bar b;
std::cout<< to::_string(b); // #<Bar 0x00001234>

has_string_converter
Checks whether there is a suitable available string converters or not.

/* int형은 내장 변환기가 있으므로 true */
std::cout<< to::has_string_converter<int>::value; // true

/* Foo 클래스는 to_string 메소드를 구현해 커스텀 변환기를 만들었으므로 true */
std::cout<< to::has_string_converter<Foo>::value; // true
/* Bar 클래스는 구현하지 않았으므로 false */
std::cout<< to::has_string_converter<Bar>::value; // false

Options

• TO_STRING_WITH_QMARKS
  std::string, char *, const char *형에 대해 to::_string을 수행할 때 문자열의 앞뒤로 "를 삽입합니다.
  이 옵션을 활용하면 STL 컨테이너에서 json 스트링을 빌드할 수 있습니다.

  #define TO_STRING_WITH_QMARKS
  
  std::map<std::string, std::vector<std::string>> m2({
    {"fruits", {"apple", "banana", "orange"}},
  	{"colors", {"yellow", "red", "blue"}}});
  std::cout<< to::_string(m2); // {"fruits" : ["apple", "banana", "orange"], "colors" : ["yellow", "red", "blue"]}

TODO

• ToString 생성기에 상속 지원