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  1. #include <iostream>
  2.  
  3. struct Java_boolean
  4. {
  5.     explicit constexpr Java_boolean( bool b = false ) : value(b) {}
  6.  
  7.     using Java_bool_t = void (Java_boolean::*)() const ;
  8.     operator Java_bool_t() const { return value ? &Java_boolean::not_integral : nullptr ; }
  9.  
  10.     int to_int() const { return value ; }
  11.     bool operator== ( Java_boolean that ) const { return value == that.value ; }
  12.     bool operator!= ( Java_boolean that ) const { return value != that.value ; }
  13.     Java_boolean operator! () const { return Java_boolean { !value } ; }
  14.  
  15.     private:
  16.         bool value ;
  17.         void not_integral() const {}
  18.  
  19.     template < typename STREAM > inline friend
  20.     STREAM& operator << ( STREAM& stm, Java_boolean b )
  21.     { return stm << "Java_" << ( b.value ? "true" : "false" ) ; }
  22. };
  23.  
  24. constexpr Java_boolean Java_true { true } ;
  25. constexpr Java_boolean Java_false { false } ;
  26.  
  27. int main()
  28. {
  29.     Java_boolean flag { Java_true } ;
  30.     if( flag ) std::cout << "ok\n" ;
  31.     if( flag == Java_true ) std::cout << "ok\n" ;
  32.     std::cout << flag << '\n' ;
  33.  
  34.     int i = flag.to_int() ; // fine
  35.     //int j = flag ; // error
  36.  
  37.     flag = Java_boolean(i) ; // fine
  38.     // flag = i ; // error
  39. }
  40.  
Success #stdin #stdout 0s 2852KB
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Standard input is empty
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ok
ok
Java_true
https://ideone.com/yvCdRP
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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