...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
For a sequence seq and function object or function pointer f, transform returns a new sequence with elements created by applying f(e) to each element of e of seq.
template< typename Sequence, typename F > typename result_of::transform<Sequence const, F>::type transform( Sequence const& seq, F f);
Table 1.55. Parameters
Parameter |
Requirement |
Description |
---|---|---|
seq |
A model of Forward Sequence |
Operation's argument |
f |
f(e) is a valid expression for each element e of seq. boost::result_of<F(E)>::type is the return type of f when called with a value of each element type E. |
Transformation function |
transform(seq, f);
Return type: A model of Forward Sequence
Semantics: Returns a new sequence, containing the return values of f(e) for each element e within seq.
template< typename Sequence1, typename Sequence2, typename F > typename result_of::transform<Sequence1 const, Sequence2 const, F>::type transform( Sequence1 const& seq1, Sequence2 const& seq2, F f);
Table 1.56. Parameters
Parameter |
Requirement |
Description |
---|---|---|
seq1 |
A model of Forward Sequence |
Operation's argument |
seq2 |
A model of Forward Sequence |
Operation's argument |
f |
f(e1,e2) is a valid expression for each pair of elements e1 of seq1 and e2 of seq2. boost::result_of<F(E1,E2)>::type is the return type of f when called with elements of type E1 and E2 |
Transformation function |
Return type: A model of Forward Sequence.
Semantics: Returns a new sequence, containing the return values of f(e1, e2) for each pair of elements e1 and e2 within seq1 and seq2 respectively.
Constant. Returns a view which is lazily evaluated.
#include <boost/fusion/algorithm/transformation/transform.hpp> #include <boost/fusion/include/transform.hpp>
struct triple { typedef int result_type; int operator()(int t) const { return t * 3; }; }; ... assert(transform(make_vector(1,2,3), triple()) == make_vector(3,6,9));