Mega Code Archive
Convenience function for the compose_f_gx adapter
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/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <vector>
#include <algorithm>
#include <functional>
#include <iterator>
using namespace std;
/* PRINT_ELEMENTS()
* - prints optional C-string optcstr followed by
* - all elements of the collection coll
* - separated by spaces
*/
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
typename T::const_iterator pos;
std::cout << optcstr;
for (pos=coll.begin(); pos!=coll.end(); ++pos) {
std::cout << *pos << ' ';
}
std::cout << std::endl;
}
/* class for the compose_f_gx adapter
*/
template <class OP1, class OP2>
class compose_f_gx_t
: public std::unary_function<typename OP2::argument_type,
typename OP1::result_type>
{
private:
OP1 op1; // process: op1(op2(x))
OP2 op2;
public:
// constructor
compose_f_gx_t(const OP1& o1, const OP2& o2)
: op1(o1), op2(o2) {
}
// function call
typename OP1::result_type
operator()(const typename OP2::argument_type& x) const {
return op1(op2(x));
}
};
/* convenience function for the compose_f_gx adapter
*/
template <class OP1, class OP2>
inline compose_f_gx_t<OP1,OP2>
compose_f_gx (const OP1& o1, const OP2& o2) {
return compose_f_gx_t<OP1,OP2>(o1,o2);
}
int main()
{
vector<int> coll;
// insert elements from 1 to 9
for (int i=1; i<=9; ++i) {
coll.push_back(i);
}
PRINT_ELEMENTS(coll);
// for each element add 10 and multiply by 5
transform (coll.begin(),coll.end(),
ostream_iterator<int>(cout," "),
compose_f_gx(bind2nd(multiplies<int>(),5),
bind2nd(plus<int>(),10)));
cout << endl;
}
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