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For a sequence seq, initial
state initial_state,
and binary function object or function pointer f,
reverse_fold returns the result of the repeated application
of binary f to the result
of the previous f invocation
(inital_state if it is
the first call) and each element of seq.
template< typename Sequence, typename State, typename F > typenameresult_of::reverse_fold<Sequence, State const, F>::type reverse_fold( Sequence& seq, State const& initial_state, F f); template< typename Sequence, typename State, typename F > typenameresult_of::reverse_fold<Sequence const, State const, F>::type reverse_fold( Sequence const& seq, State const& initial_state, F f);
Table 1.41. Parameters
|
Parameter |
Requirement |
Description |
|---|---|---|
|
|
A model of Bidirectional Sequence |
Operation's argument |
|
|
Any type |
Initial state |
|
|
|
Operation's argument |
reverse_fold(seq, initial_state, f);
Return type: Any type
Semantics: Equivalent to f(...
f(f(initial_state,eN),eN-1) ...e1) where e1 ...eN
are the consecutive elements of seq.
Linear, exactly applications of result_of::size<Sequence>::valuef.
#include <boost/fusion/algorithm/iteration/reverse_fold.hpp> #include <boost/fusion/include/reverse_fold.hpp>
struct make_string
{
typedef std::string result_type;
template<typename T>
std::string operator()(const std::string& str, const T& t) const
{
return str + boost::lexical_cast<std::string>(t);
}
};
...
const vector<int,int> vec(1,2);
assert(reverse_fold(vec,std::string(""), make_string()) == "21");