Re: STL algorithm member function problem
In article <161120061749010683%cbarron413@adelphia.net>, Carl Barron
<cbarron413@adelphia.net> wrote:
In article <fZX6h.44807$uv5.305674@twister1.libero.it>, Alberto Ganesh
Barbati <AlbertoBarbati@libero.it> wrote:
Except that it doesn't work because *p is an abstract class and that
it's very inefficient because strings may be moved many times. It's
better to keep remove_if/erase as the "outer loop" rather than keep it
in the "inner loop".
A solution using boost/tr1 function<bool(string const &)> avoids any
slicing discusion, but I am not so sure there is ever a conversion from
Rule & to Rule in the expansion of remove_if. [shared_ptr::operator *()
returns a Rule & not a Rule].
As far as copying strings, there is the same # of copies performed
whether a home made loop is done or for_each is performed since the
container is held by reference,
[snip]
Ignore the response as it compiles because it does not work.
I prefer a container of function<bool(const std::string &)> It does not
require any derivation from a base class for any of the functor
objects, functions, or even member functions of a given class/struct.
Further I like the idea for testing each string in the listing and
removing those which succeed for any of the container<function<...> >.
If copying is a problem then consider finding the element to remove,
swapping it with the last entry, decrementing end then if end is
returned the range[end, container.end()) can be erased.
assuming that [test_begin,test.end) is a sequence of iterators so that
it in the sequence (*it)(const std::string &) is a tests if a condition
is satified by the argument. then
BI is a bidirectional iterator, and For is a forward_iterator.
template <class BI,class For>
BI remove_if_any
(
BI begin,BI end,
For test_begin,For test_end
)
{
while((begin = std::find_if(begin,end,any_of(test_begin,test_end)))
!=end)
{
using std::swap;
if(--end == begin)
{
break; // one entry left and we want it gone...
}
swap(*begin,*end);
}
return end;
}
behaves like std::remove_if does not erase anything.
This swaps the strings out of the sequence but rearranges the order
of the strings. If order is unimportant and the size and or # is large
this may be more efficient.
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