SCIP in C++11 ― 3.1.1節その2

アキュミュレータ・呼び出しカウントと問題3.1～3.2

なんかうまくいってるみたいだが、右辺値参照がまだ気持ち悪い。

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const function<List(int)> makeAccumulator(const List& stateValueIn)

{

    const List&& stateValue(std::move(stateValueIn));

    return([stateValue](const int augend){

         setInsert(stateValue+makeLeaf(augend),stateValue);

         return(stateValue);

        

     });

}

const function<List(List)> makeMonitored(const List& fIn)

{

    const List count(makeLeaf(0));

    const List&& f(std::move(fIn));

    const function<List(List)> executeF

     =[f,count](const List& argument){

     setInsert(count+makeLeaf(1),count);

     return(executable<List,List>(f)(argument));

    };

   

    const function<List(List)> callCount

     =[count](const List dummy){return(count);};

    const function<List(List)> resetCount

     =[count](const List dummy){

     setInsert(makeLeaf(0),count);

     return(count);

    };

    const function<List(List)> mf

     =[executeF,callCount,resetCount](const List& message){

     if(isNumber(message)){return(executeF(message));}

     if(isEq(message,makeLeaf("how-many-calls?")))

         {return(callCount(makeList()));}

     if(isEq(message,makeLeaf("reset-count")))

         {return(resetCount(makeList()));}

     cerr<<"Unknown request --- MAKE-MONITORED"<<endl;

     exit(1);

     return(makeList());

    };

    return(mf);

}

const function<List(List)> squareRoot

=[](const List& x){return(makeLeaf(sqrt(value<double>(x))));};

int main(int argc, char** argv)

{

    const auto A(makeAccumulator(makeLeaf(5)));

    cout<<"Excersize 3.1:"<<endl;

    cout<<"(A 10) = "<<listString(A(10))<<endl;

    cout<<"(A 10) = "<<listString(A(10))<<endl;

    cout<<endl<<"Excersize 3.2:"<<endl;

    const auto s(makeMonitored(makeLeaf(squareRoot)));

    cout<<"(s 100) = "<<listString(s(makeLeaf(100)))<<endl;

    cout<<"(s 25) = "<<listString(s(makeLeaf(25)))<<endl;

    cout<<"(s 'how-many-calls?) = "

     <<listString(s(makeLeaf("how-many-calls?")))<<endl;

    cout<<"(s 'reset-count) = "

     <<listString(s(makeLeaf("reset-count")))<<endl;

    cout<<"(s 49) = "<<listString(s(makeLeaf(49)))<<endl;

    cout<<"(s 'how-many-calls?) = "

     <<listString(s(makeLeaf("how-many-calls?")))<<endl;

    return(0);

}

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出力

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Excersize 3.1:

(A 10) = 15

(A 10) = 25

Excersize 3.2:

(s 100) = 10

(s 25) = 5

(s 'how-many-calls?) = 2

(s 'reset-count) = 0

(s 49) = 7

(s 'how-many-calls?) = 1