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C++ã§Functorã«ã‚ˆã‚‹å‡¦ç†ã®åˆ‡ã‚Šæ›¿ãˆ

/ Published in: C++

å‚è€ƒï¼š
1. http://www.newty.de/fpt/functor.html
-- ã»ã¨ã‚“ã©ã€ã“ã®ã‚³ãƒ¼ãƒ‰ã«ã‚³ãƒ¡ãƒ³ãƒˆã‚’åŠ ãˆãŸã ã‘ã§ã™w
2. http://d.hatena.ne.jp/nurs/20080125/1201278130
-- æœ€åˆã“ã®ãƒšãƒ¼ã‚¸ã‚’è¦‹ã¤ã‘ãŸã®ã§ã™ãŒã€ã“ã®æ–¹æ³•ã ã¨å®Ÿè¡Œæ™‚ã«ãƒ•ã‚¡ãƒ³ã‚¯ã‚¿ï¼ˆé–¢æ•°ã‚ªãƒ–ã‚¸ã‚§ã‚¯ãƒˆï¼‰ã‚’ä½œã£ã¦ã€é…åˆ—ã«å…¥ã‚Œã¦å‡¦ç†ã‚’åˆ‡ã‚Šæ›¿ãˆã€ã£ã¦ã“ã¨ãŒå‡ºæ¥ãªã„ã¨æ€ã£ãŸã®ã§ã€ã“ã®ã‚³ãƒ¼ãƒ‰ã‚’æ›¸ãã¾ã—ãŸã€‚
3. http://www.mokehehe.com/assari/index.php?C%2B%2B%2F%A5%E1%A5%F3%A5%D0%B4%D8%BF%F4%A4%CE%A5%DD%A5%A4%A5%F3%A5%BF
-- ä¼¼ã¦ã‚‹ã‹ã‚‚

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#include <iostream>
//------------------------------ ã‚ã‚‰ã‚†ã‚‹functorã®å…ƒ
class FunctorBaseClass{
public:
  // ä»®æƒ³é–¢æ•°ã§å®Ÿè¡Œã®ã•ã‚Œã‹ãŸã®ã¿ã‚’å®šç¾©ã™ã‚‹ï¼Ž
  // ï¼ˆã“ã“ã§ã¯()æ¼”ç®—åã®ã‚ªãƒ¼ãƒãƒ¼ãƒãƒ¼ãƒ‰ï¼‰
  virtual double operator()(double val){};
};
//------------------------------ å…ˆã®ã‚¯ãƒ©ã‚¹ã®ç¶™æ‰¿
template <class TClass>
class SpecificFunctor : public FunctorBaseClass{
public:
  // pt2func : ãƒ¡ãƒ³ãƒé–¢æ•°ã¸ã®ãƒã‚¤ãƒ³ã‚¿
  double (TClass::*pt2func)(double);
  // pt2obj  ; ã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹ã¸ã®ãƒã‚¤ãƒ³ã‚¿
  TClass* pt2obj;
  SpecificFunctor(TClass* _pt2obj, double(TClass::*_pt2func)(double)){
    pt2obj  = _pt2obj;  // TClassã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹ã¸ã®ãƒã‚¤ãƒ³ã‚¿ã‚’ãƒ¡ãƒ³ãƒå¤‰æ•°ã¸ä»£å…¥
    pt2func = _pt2func; // TClassãƒ¡ãƒ³ãƒé–¢æ•°  ã¸ã®ãƒã‚¤ãƒ³ã‚¿ã‚’ãƒ¡ãƒ³ãƒå¤‰æ•°ã¸ä»£å…¥
  }
  virtual double operator()(double val){
    // ã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹.ãƒ¡ãƒ³ãƒé–¢æ•°(å¼•æ•°) ã®å½¢ã§å®Ÿè¡Œ
    return (*pt2obj.*pt2func)(val);
  }
};
//------------------------------ å‡¦ç†(1)
class PlusOne{
public:
  double func(double val) {
    return val+1;
  }
};
//------------------------------ å‡¦ç†(2)
class PlusA{
public:
  double a;
  PlusA(double _a) {
    a = _a;
  }
  double func(double val) {
    return val+a;
  }
};
//------------------------------ ä½¿ç”¨ä¾‹
int main(){
  PlusOne obj1;
  PlusA   obj2(2);

// ã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹ã¨å®Ÿè¡Œã™ã‚‹ãƒ¡ãƒ³ãƒé–¢æ•°ã‚’å¼•æ•°ã«ã¨ã£ã¦ã‚¤ãƒ³ã‚¹ã‚¿ãƒ³ã‚¹ä½œæˆ
  SpecificFunctor< PlusOne > specFunc1(&obj1, &PlusOne::func);
  SpecificFunctor< PlusA   > specFunc2(&obj2, &PlusA  ::func);
  // ç¶™æ‰¿å…ƒã®ã‚¯ãƒ©ã‚¹ã®ãƒã‚¤ãƒ³ã‚¿ã®é…åˆ—ã«ä»£å…¥å‡ºæ¥ã‚‹
  FunctorBaseClass* vTable[] = { &specFunc1, &specFunc2 };
  // å®Ÿè¡Œã—ã¦ã¿ã‚‹
  std::cout << "PlusOne::func(1) = "
	    << (*vTable[0])(1) << std::endl;
  std::cout << "PlusA  ::func(1) = "
	    << (*vTable[1])(1) << std::endl;
  return 0;
}

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